% Encoding: UTF-8 @COMMENT{BibTeX export based on data in FAU CRIS: https://cris.fau.de/} @COMMENT{For any questions please write to cris-support@fau.de} @article{faucris.123154284, abstract = {The adsorption behavior of 2H-tetrakis(3,5-di-tert-butyl)phenylporphyrin (2HTTBPP) on Cu(110) and Cu(110)-(2x1)O surfaces have been investigated by using variable-temperature scanning tunneling microscopy (STM) under ultrahigh vacuum conditions. On the bare Cu(110) surface, individual 2HTTBPP molecules are observed. These molecules are immobilized on the surface with a particular orientation with respect to the crystallographic directions of the Cu(110) surface and do not form supramolecular aggregates up to full monolayer coverage. In contrast, a chiral supramolecular structure is formed on the Cu(110)-(2x1)O surface, which is stabilized by van der Waals interactions between the tert-butyl groups of neighboring molecules. These findings are explained by weakened molecule-substrate interactions on the Cu(110)-(2x1)O surface relative to the bare Cu(110) surface. By comparison with the corresponding results of Cu-tetrakis(3,5-di-tert-butyl)phenylporphyrin (CuTTBPP) on Cu(110) and Cu(110)-(2x1)O surfaces, we find that the 2HTTBPP molecules can self-metalate on both surfaces with copper atoms from the substrate at room temperature (RT). The possible origins of the self-metalation reaction at RT are discussed. Finally, peculiar irreversible temperature-dependent switching of the intramolecular conformations of the investigated molecules on the Cu(110) surface was observed and interpreted.}, author = {Zhang, Liang and Lepper, Michael and Stark, Michael Werner and Schuster, Ralf and Lungerich, Dominik and Jux, Norbert and Steinrück, Hans-Peter and Marbach, Hubertus}, doi = {10.1002/chem.201504214}, faupublication = {yes}, journal = {Chemistry - A European Journal}, keywords = {adsorption;porphyrinoids;scanning tunneling microscopy;self-assembly;surfaces and interfaces}, pages = {3347-3354}, peerreviewed = {Yes}, title = {{2H}-{Tetrakis}(3,5-di-tert-butyl)phenylporphyrin on a {Cu}(110) {Surface}: {Room}-{Temperature} {Self}-{Metalation} and {Surface}-{Reconstruction}-{Facilitated} {Self}-{Assembly}}, volume = {22}, year = {2016} } @book{faucris.120373704, address = {Berlin, Heidelberg}, author = {Held, Georg and Steinrück, Hans-Peter}, doi = {10.1007/10932216{\_}11}, editor = {H. P. Bonzel - Institut für Schichten und Grenzflächen (ISG 3), Forschungszentrum Jülich}, faupublication = {yes}, pages = {300-308}, publisher = {Springer Berlin Heidelberg}, series = {Landolt-Börnstein - Group II Condensed Matter - Absorbed Layers on Surfaces - Absorbed Species on Surfaces and Adsorbate-Induced Surface Core Level}, title = {3.8.7 {Cyclic} {Hydrocarbons}}, url = {http://link.springer.com/chapter/10.1007%2F10932216{\_}11}, volume = {42A4}, year = {2005} } @article{faucris.114130764, abstract = {Using X-ray photoelectron spectroscopy (XPS) and scanning tunneling microscopy (STM), the coverage-dependent self-metalation of 2H- tetraphenylporphyrin (2HTPP) with Cu on Cu(111) at 400 K has been studied. At low coverages the porphyrin molecules are adsorbed as isolated molecules, and the rate of metalation is slow. As the coverage is increased beyond &sim;0.36 molecules/nm, a supramolecular checkerboard structure is formed, with every second molecule slightly elevated above the surface. The appearance of this checkerboard structure coincides with a dramatic increase in the rate of metalation. This enhancement is attributed to a smaller activation barrier for the elevated molecules, which have an internal conformation similar to that of the free molecule, whereas the less reactive molecules in direct contact with the surface are strongly distorted. &copy; 2013 American Chemical Society.}, author = {Röckert, Michael and Ditze, Stefanie and Stark, Michael Werner and Xiao, Jie and Steinrück, Hans-Peter and Marbach, Hubertus and Lytken, Ole}, doi = {10.1021/jp412121b}, faupublication = {yes}, journal = {Journal of Physical Chemistry C}, pages = {1661-1667}, peerreviewed = {Yes}, title = {{Abrupt} coverage-induced enhancement of the self-metalation of tetraphenylporphyrin with {Cu}(111)}, volume = {118}, year = {2014} } @article{faucris.279009721, abstract = {Understanding the adsorption of organic molecules on surfaces is of essential importance for many applications. Adsorption energies are typically measured using temperature-programmed desorption. However, for large organic molecules, often only desorption of the multilayers is possible, while the bottom monolayer in direct contact to the surface cannot be desorbed without decomposition. Nevertheless, the adsorption energies of these directly adsorbed molecules are the ones of the most interest. We use a layer-exchange process investigated with X-ray photoelectron spectroscopy to compare the relative adsorption energies of several metalated tetraphenylporphyrins on rutile TiO2(110) 1 x 1. We deposit a mixture of two different molecules, one on top of the other, and slowly anneal above their multilayer desorption temperature. During the slow heating, the molecules begin to diffuse between the layers and the molecules with the stronger interaction with the surface displace the weaker-interacting molecules from the surface and push them into the multilayer. The multilayers eventually desorb, leaving behind a monolayer of strongly interacting molecules. From the ratio of the two different porphyrin molecules in the residual monolayer and the desorbed multilayer, we can calculate the equilibrium constant of the layer-exchange process and thereby the difference in adsorption energy between the two different porphyrin molecules.}, author = {Muth, Maximilian and Wolfram, Alexander and Kataev, Elmar and Köbl, Julia and Steinrück, Hans-Peter and Lytken, Ole}, doi = {10.1021/acs.langmuir.2c01054}, faupublication = {yes}, journal = {Langmuir}, note = {CRIS-Team WoS Importer:2022-07-29}, peerreviewed = {Yes}, title = {{Accurate} {Determination} of {Adsorption}-{Energy} {Differences} of {Metalloporphyrins} on {Rutile} {TiO2}(110) 1 x 1}, year = {2022} } @article{faucris.108277884, abstract = {An aromatic triphenylene molecule (2,3-diethyl-1,4-dimethoxytriphenylene; TPH) and its regioselectively Cr(CO)-labeled complex (&eta;-(1,2,3,4,4a,12b)-tricarbonyl(2,3-diethyl-1, 4-dimethoxytriphenylene)chromium(0); &alpha;-TPHC) were deposited on a Ag(111) surface by vapor deposition. The monolayers were investigated by X-ray photoelectron spectroscopy and scanning tunneling microscopy. Both substances adsorb with the extended &pi;-system parallel to the surface and form long-range ordered monolayers. The Cr(CO) group of the &alpha;-TPHC complex is oriented toward the vacuum. Although the footprints of both substances are similar, the additional Cr(CO) group on the &alpha;-TPHC leads to a lateral order (unit cell) that is significantly different from that of TPH. &copy; 2009 American Chemical Society.}, author = {Schmitz, Christoph H. and Rang, Carola and Bai, Yun and Kossev, Iordan and Ikonomov, Julian and Su, Yang and Kotsis, Konstantinos and Soubatch, Serguei and Neucheva, Olga and Tautz, F. Stefan and Neese, Frank and Steinrück, Hans-Peter and Gottfried, J. Michael and Doetz, Karl Heinz and Sokolowski, Moritz}, doi = {10.1021/jp810788n}, faupublication = {yes}, journal = {Journal of Physical Chemistry C}, pages = {6014-6021}, peerreviewed = {Yes}, title = {{A} comparative study of a triphenylene tricarbonyl chromium complex and its uncoordinated arene ligand on the {Ag}(111) surface: {Influence} of the complexation on the adsorption}, volume = {113}, year = {2009} } @article{faucris.120338504, abstract = {We have investigated the activated adsorption of methane on Pt(111) by the combination of a supersonic molecular beam and in situ high-resolution X-ray photoelectron spectroscopy at the German synchrotron radiation facility BESSY II. On exposing the surface to a methane beam with kinetic energies between 0.30 and 0.83eV, CH is formed as a stable species at 120 K; upon heating, at around 260 K the adsorbed methyl partly dehydrogenates to CH and partly recombines to methane, which desorbs. Upon adsorption at 300 K, CH is directly formed as a stable surface species. To verify the chemical identity of CH as an intermediate, we have also investigated the thermal evolution of a saturated ethylene layer. Upon heating, at &sim; 290 K partial ethylene desorption and the formation of ethylidyne is clearly observed in the spectra, as expected from the literature. From the binding energies and also from the vibrational signature of the C 1s spectra, an unequivocal assignment of the various surface species is possible. Measurements of the sticking coefficients of methane show that the saturation coverage at 120 K depends on the kinetic energy of the molecule; furthermore, the sticking coefficient for vibrationally excited molecules is strongly enhanced. &copy; IOP Publishing Ltd and Deutsche Physikalische Gesellschaft.}, author = {Fuhrmann, Thomas and Kinne, Markus and Tränkenschuh, Barbara and Papp, Christian and Zhu, Junfa and Denecke, Reinhard and Steinrück, Hans-Peter}, doi = {10.1088/1367-2630/7/1/107}, faupublication = {yes}, journal = {New Journal of Physics}, peerreviewed = {Yes}, title = {{Activated} adsorption of methane on {Pt} (111) - {An} in situ {XPS} study}, volume = {7}, year = {2005} } @article{faucris.120317384, abstract = {By simply counting individual molecules in STM images after defined heating steps, the kinetic parameters and the activation energy of a complex surface reaction can be determined quantitatively. This procedure was demonstrated for the metalation of 2H-tetraphenylporphyrin (2HTPP) with substrate atoms on a Cu(111) surface. Copyright &copy; 2012 WILEY-VCH Verlag GmbH &amp; Co. KGaA, Weinheim.}, author = {Ditze, Stefanie and Stark, Michael Werner and Drost, Martin and Buchner, Florian and Steinrück, Hans-Peter and Marbach, Hubertus}, doi = {10.1002/anie.201205464}, faupublication = {yes}, journal = {Angewandte Chemie International Edition}, pages = {10898-10901}, peerreviewed = {Yes}, title = {{Activation} energy for the self-metalation reaction of {2H}- tetraphenylporphyrin on {Cu}(111)}, volume = {51}, year = {2012} } @article{faucris.108457404, author = {Hamza, Alex and Steinrück, Hans-Peter and Madix, R.J.}, faupublication = {no}, journal = {Journal of Chemical Physics}, pages = {7494-7495}, peerreviewed = {Yes}, title = {{Activation} of n-butane with translational energy on {Ir}(110)-(1×2)}, url = {https://www.scopus.com/record/display.uri?eid=2-s2.0-0000473355&origin=inward}, volume = {85}, year = {1986} } @article{faucris.108304724, abstract = {The vibrational fine structure of x-ray photoelectron (XP) spectra of a number of different small hydrocarbon molecules and reaction intermediates adsorbed on Pt(111) and Ni(111) has been investigated in detail. The data for methyl, methylidyne, acetylene, and ethylene can consistently be analyzed within the linear coupling model. The S factor, i.e., the intensity ratio of the first vibrationally excited to the adiabatic transition, is obtained to be 0.17&plusmn;0.02 per C-H bond; for the deuterated species a value of 0.23&plusmn;0.02 is obtained. Therefore, the vibrational fine structure can be used for fingerprinting in the analysis of XP spectra and for identifying unknown reaction intermediates. From the data, &Delta;r, the change of the minimum in the potential energy curve upon core ionization, is calculated within the linear coupling model using a first order correction. For all adsorbates, including the deuterated ones, a value of &Delta;r=0.060&plusmn;0.004 &Aring; is obtained. Furthermore, from the binding energy of the adiabatic peak and from the energy of the vibrational excitation in the ionic final state some information on the adsorbate/substrate bond and the adsorption site can be derived. &copy; 2006 American Institute of Physics.}, author = {Steinrück, Hans-Peter and Fuhrmann, Thomas and Papp, Christian and Tränkenschuh, Barbara and Denecke, Reinhard}, doi = {10.1063/1.2397678}, faupublication = {yes}, journal = {Journal of Chemical Physics}, peerreviewed = {Yes}, title = {{A} detailed analysis of vibrational excitations in x-ray photoelectron spectra of adsorbed small hydrocarbons}, volume = {125}, year = {2006} } @article{faucris.113935404, abstract = {A comprehensive theory of the adsorption of CO on Pt(1 1 1) is developed to describe equilibrium properties as well as the adsorption and desorption kinetics. The basis is a multi-site lattice gas model which allows for adsorption at on-top and bridge sites, and includes site exclusion and lateral interactions out to second neighbour unit cells as well as a mean field to account for long ranged dipolar interactions between CO molecules. The theory reproduces the coverage and temperature dependence of pressure isotherms, partial coverages, heat of adsorption, total sticking coefficients, and isothermal and temperature-programmed desorption rates. The quality of the fits and the internal consistency of the theory are such that a number of minor inconsistencies in available experimental data can be identified and discussed. © 2003 Elsevier B.V. All rights reserve}, author = {Mcewen, Jean-Sabin and Payne, Stephen H. and Kreuzer, Hans Jürgen and Kinne, Martin and Denecke, Reinhard and Steinrück, Hans-Peter}, doi = {10.1016/j.susc.2003.08.040}, faupublication = {yes}, journal = {Surface Science}, keywords = {Equilibrium thermodynamics and statistical mechanics; Models of surface kinetics; X-ray photoelectron spectroscopy; Adsorption kinetics; Sticking; Thermal desorption; Platinum; Carbon monoxide}, pages = {47-69}, peerreviewed = {Yes}, title = {{Adsorption} and desorption of {CO} on {Pt}(1 1 1): {A} comprehensive analysis}, url = {http://www.sciencedirect.com/science/article/pii/S0039602803011257}, volume = {545}, year = {2003} } @article{faucris.107800704, abstract = {We investigated the adsorption and thermal evolution of acetylene on clean Pd(100) and Pd(100) precovered with 0.25 ML oxygen. The measurements were performed in situ by fast XPS at the synchrotron radiation facility BESSY II. On Pd(100) acetylene molecularly adsorbs at 130 K. Upon heating transformation to a CCH species occurs around 390 K along with the formation of a completely dehydrogenated carbon species. On the oxygen-precovered surface partial CCH formation already occurs upon adsorption at 130 K, and the dehydrogenation temperature and the stability range of CCH are shifted to lower temperatures by &sim;200 K. &copy; 2013 AIP Publishing LLC.}, author = {Höfert, Oliver and Lorenz, Michael Peter Andreas and Streber, Regine and Zhao, Wei and Bayer, Andreas and Steinrück, Hans-Peter and Papp, Christian}, doi = {10.1063/1.4825112}, faupublication = {yes}, journal = {Journal of Chemical Physics}, pages = {164706 1-7}, peerreviewed = {Yes}, title = {{Adsorption} and reaction of acetylene on clean and oxygen-precovered {Pd}(100) studied with high-resolution {X}-ray photoelectron spectroscopy}, volume = {139}, year = {2013} } @article{faucris.108305604, abstract = {We studied the adsorption and reaction of cyclohexene (CH ) on Ni(111) at different temperatures with highresolution in-situ X-ray photoelectron spectroscopy (HR-XPS). For exposure at 125 K, we find intact cyclohexene with two distinct C Is signals at 283.3 and 284.2 eV, due to the nonequivalent carbon atoms in the molecule. The energetic separation is significantly increased relative to the gas-phase value, due to the interaction with the substrate. Upon exposure at 210 K, complete dehydrogenation of cyclohexene to benzene (CH) and hydrogen is observed; coverage-dependent changes of the benzene adsorption site occur in a way similar to those for pure benzene layers, which indicates a phase separation in benzene and hydrogen islands. The thermal evolution of the adsorbed layers was studied by temperature-programmed (TP-) XPS and temperature-programmed desorption spectroscopy (TPD). Upon heating, the benzene + hydrogen layer formed at 210 K shows a coverage-dependent reorientation of the benzene molecules during partial desorption. The cyclohexene layer adsorbed at 125 K only shows partial conversion of cyclohexene to benzene and hydrogen upon heating to 185 or 210 K, with the remaining cyclohexene being stable up to &sim;300 K. We propose that upon heating these molecules are stabilized by coadsorbed benzene and hydrogen; furthermore, the mobility of benzene and hydrogen in this coadsorbed layer is reduced, so that no phase separation can occur. &copy; 2007 American Chemical Society.}, author = {Papp, Christian and Denecke, Reinhard and Steinrück, Hans-Peter}, doi = {10.1021/la0635909}, faupublication = {yes}, journal = {Langmuir}, pages = {5541-5547}, peerreviewed = {Yes}, title = {{Adsorption} and reaction of cyclohexene on a {Ni}(111) surface}, volume = {23}, year = {2007} } @article{faucris.120338944, abstract = {The adsorption of methanol on the clean and oxygen precovered Cu(111) surface was studied by means of high resolution X-ray photoelectron spectroscopy (XPS), ultraviolet photoelectron spectroscopy (UPS), and temperature programmed desorption (TPD). On clean Cu(111) methanol is adsorbed molecularly at 100 K. Only small amounts of methoxy are formed by heating to 160-180 K, whereas the main part of methanol desorbs molecularly. The formation of methoxy drastically increases on the oxygen precovered surface. In the UP spectra the peaks of molecular methanol disappear and the peaks of methoxy develop. TPD measurements show that methoxy desorbs dissociatively as formaldehyde and hydrogen with the rate maxima at around 430 K. The efficiency of the oxidation of methanol to formaldehyde depends on the amount of predosed oxygen, with a maximum methoxy coverage obtained for an oxygen precoverage of 0.18 ML. From the quantitative analysis we propose an additional reaction pathway involving not only the formation, but also the decomposition of an hydroxyl intermediate, parallel to the previously reported pathway, which leads to the desorption of wate}, author = {Pöllmann, Silke Andrea and Bayer, Andreas and Ammon, Christian and Steinrück, Hans-Peter}, doi = {10.1524/zpch.218.8.957.35981}, faupublication = {yes}, journal = {Zeitschrift für Physikalische Chemie-International Journal of Research in Physical Chemistry & Chemical Physics}, pages = {957-971}, peerreviewed = {Yes}, title = {{Adsorption} and reaction of methanol on clean and oxygen precovered {Cu}(111)}, volume = {218}, year = {2004} } @article{faucris.121296164, abstract = {We studied the adsorption and reactivity of SO on clean and oxygen precovered Pd(100) with high resolution X-ray photoelectron spectroscopy and density functional calculations. Upon adsorption at 120 K two different SO species were detected, which were identified as upright-standing and flat-lying molecules by comparing the calculated core level shifts. In agreement with the relative stabilities determined by the calculations the intensities of the photoelectron spectra indicate that the majority species are upright-standing SO . Upon heating the quantitative analysis of the data indicates desorption of SO and formation of atomic sulfur. On the oxygen precovered surface small amounts of SO are formed already upon SO adsorption at low temperatures. Upon heating stepwise oxidation of SO to SO and, eventually, to SO is found. Two different SO species were detected, which are assigned to SO bound in the proximity of or remote from oxygen adatoms, according to core level shift estimates. &copy; 2011 the Owner Societies.}, author = {Luckas, Nicola and Gotterbarm, Karin and Streber, Regine and Lorenz, Michael Peter Andreas and Höfert, Oliver and Vines, Francesc and Papp, Christian and Görling, Andreas and Steinrück, Hans-Peter}, doi = {10.1039/c1cp21694e}, faupublication = {yes}, journal = {Physical Chemistry Chemical Physics}, pages = {16227-16235}, peerreviewed = {Yes}, title = {{Adsorption} and reaction of {SO2} on clean and oxygen precovered {Pd}(100) - {A} combined {HR}-{XPS} and {DF} study}, volume = {13}, year = {2011} } @article{faucris.117429444, abstract = {Atomic sulfur and its oxides are common catalyst poisons and intriguing research subjects. Recently, graphene-supported nanoclusters were introduced as suitable model catalysts. We investigated the adsorption and reaction of SO2 on graphene-supported Pt nanocluster arrays with high-resolution X-ray photoelectron spectroscopy. SO2 adsorbs in two geometries-perpendicular and parallel to the surface-on both cluster facets and steps. Further insight is gained from the comparison of our results to previous data of SO2 on Pt(111) and two stepped single crystal surfaces-Pt(322) and Pt(355)-with (100) and (111) steps, respectively. We find a remarkable similarity to the adsorption situation on Pt(322). However, thermal evolution experiments revealed several similarities to both Pt(322) and Pt(355), showing that the Pt nanoclusters exhibit a mixture of (100) and (111) steps.}, author = {Gotterbarm, Karin and Späth, Florian and Bauer, Udo and Steinrück, Hans-Peter and Papp, Christian}, doi = {10.1007/s11244-015-0407-8}, faupublication = {yes}, journal = {Topics in Catalysis}, keywords = {XPS;Platinum;Nanoclusters;SO2;Graphene}, pages = {573-579}, peerreviewed = {Yes}, title = {{Adsorption} and {Reaction} of {SO2} on {Graphene}-{Supported} {Pt} {Nanoclusters}}, volume = {58}, year = {2015} } @article{faucris.107824684, abstract = {The adsorption and reaction of terephthaloyl chloride (TPC) on a Ag(111) surface was investigated with X-ray photoelectron spectroscopy (XPS) and density functional theory (DFT) calculations. Below 120 K, TPC forms multilayers without reacting with the Ag(111) substrate. Multilayer desorption starts above 120 K and is accompanied by a chemical reaction between the TPC molecules and the Ag surface. This reaction involves scission of the carbon-chlorine bond, resulting in the formation of adsorbed chlorine atoms and a p-phenylene dicarbonyl (pPDC) species. This molecular fragment is stable at room temperature and does not undergo further decomposition, presumably due to stabilization by adsorbate-substrate interactions and/or oligomerization. The DFT calculations confirm that pPDC is a possible intermediate or final reaction product and show that the two carbonyl C atoms form covalent bonds to the Ag substrate. &copy; 2011 American Chemical Society.}, author = {Schmid, Martin and Hieringer, Wolfgang and Schmitz, Christoph H. and Steinrück, Hans-Peter and Sokolowski, Moritz and Gottfried, Michael}, doi = {10.1021/jp2033017}, faupublication = {yes}, journal = {Journal of Physical Chemistry C}, pages = {14869-14875}, peerreviewed = {Yes}, title = {{Adsorption} and reaction of terephthaloyl chloride on {Ag}(111): {X}-ray photoelectron spectroscopy and density functional theory investigations}, volume = {115}, year = {2011} } @article{faucris.314055145, abstract = {In the context of ionic liquid (IL)-assisted catalysis, we have investigated the adsorption and thermal evolution of the IL 1,3-dimethylimidazolium bis(trifluoromethylsulfonyl)imide ([C1C1Im][Tf2N]) on Pt(111) between 100 and 800 K by angle-resolved X-ray photoelectron spectroscopy and scanning tunneling microscopy. Defined amounts of IL in the coverage range of a complete first wetting layer were deposited at low temperature (100-200 K), and subsequently heated to 300 K, or directly at 300 K. At 100 K, the IL adsorbs as an intact disordered layer. Upon heating to 200 K, the IL stays intact, but forms an ordered and well-oriented structure. Upon heating to 250 K, the surface order increases, but at the same time STM and XPS indicate the onset of decomposition. Upon heating to 300 K, decomposition progresses, such that 50-60% of the IL is decomposed. The anion-related reaction products desorb instantaneously, and the cation-related products remain on the surface. Thereby, the surface is partly passivated, enabling the remaining IL to still be adsorbed intact at 300 K. For IL deposition directly at 300 K, a fraction of the IL instantaneously decomposes, with the anion-related products desorbing, opening free space for further deposition of IL. Hence, cation-related species accumulate at the expense of anions, until one fully closed wetting layer is formed. As a consequence, a higher dose is required to reach this coverage at 300 K, compared to 100-200 K.}, author = {Massicot, Stephen and Gezmis, Emine and Talwar, Timo and Meusel, Manuel and Jaekel, Simon and Adhikari, Rajan and Winter, Leonhard and Fernández Fernández, Cynthia and Bayer, Andreas and Maier, Florian and Steinrück, Hans-Peter}, doi = {10.1039/d3cp02743k}, faupublication = {yes}, journal = {Physical Chemistry Chemical Physics}, note = {CRIS-Team Scopus Importer:2023-11-17}, pages = {27953-27966}, peerreviewed = {Yes}, title = {{Adsorption} and thermal evolution of [{C1C1Im}][{Tf2N}] on {Pt}(111)}, volume = {25}, year = {2023} } @article{faucris.113334804, abstract = {The adsorption and thermal evolution of SO on a Pt(110) surface was studied by temperature programmed desorption, angle-resolved UV photoelectron spectroscopy and X-ray photoelectron spectroscopy. At 140 K two molecular SO species are observed that are attributed to adsorption on different adsorption sites. Upon heating to 340 K atomic S and molecular SO and SO are formed with the amount of the various products depending on the initial SO coverage. For high SO coverages these reactions are accompanied by molecular SO desorption. The SO species decomposes upon further heating to 500 K leading to SO desorption. SO, which is only formed for high initial SO coverages, is stable up to this temperature but decomposes upon further heating to 650 K. In the same temperature range atomic sulphur and oxygen recombine to desorb as SO.}, author = {Zebisch, P. and Stichler, M. and Trischberger, P. and Weinelt, M. and Steinrück, Hans-Peter}, doi = {10.1016/S0039-6028(96)01019-9}, faupublication = {no}, journal = {Surface Science}, pages = {235-244}, peerreviewed = {Yes}, title = {{Adsorption} and thermal evolution of {SO2} on the {Pt}(110) surface}, volume = {371}, year = {1997} } @article{faucris.119845704, abstract = {We investigate the impact of peripheral cyano functionalization of the previously well-studied 2H-tetraphenylporphyrin (2HTPP) by scanning tunneling microscopy (STM) and density functional theory (DFT). The adsorption behavior of 2H-tetralds(p-cyano)-phenylporphyrin (2HTCNPP) is studied at room temperature and at 80 K on Cu(111) and Ag(111). Interestingly, the cyano-functionalized porphyrins tend to form isolated ID chains on Cu(111), in particular after mild annealing at 350 K. The individual 2HTCNPPs as well as the formed chains are oriented along the main crystallographic directions of the Cu(111) substrate due to a strongly attractive and site-specific interaction between the iminic nitrogens of the 2HTCNPP and Cu substrate atoms. The linking within the 1D molecular chains is realized by Cu adatoms as evidenced by comparison of STM and DFT. In contrast, on Ag(111) the molecules assemble into 2D supramolecular layers with long-range order and a square unit cell, stabilized by molecule-molecule interactions. The orientation of the molecules with respect to the unit cell lattice vectors leads to organizational chirality. By codeposition of cobalt, the porphyrin molecules are metalated at room temperature. We did not observe any evidence for metal-organic network formation on Ag(111), even after varying the deposition parameters or the order of metal and porphyrin deposition. Our study shows that cyano functionalization of porphyrins can give rise to novel and unique self-assembled structures like 1D molecular chains without any cross-connections via adatom linking.}, author = {Lepper, Michael and Schmitt, Tobias and Gurrath, Martin and Raschmann, Marco and Zhang, Liang and Stark, Michael Werner and Hölzel, Helen and Jux, Norbert and Meyer, Bernd and Schneider, M. Alexander and Steinrück, Hans-Peter and Marbach, Hubertus}, doi = {10.1021/acs.jpcc.7b08382}, faupublication = {yes}, journal = {Journal of Physical Chemistry C}, pages = {26361-26371}, peerreviewed = {Yes}, title = {{Adsorption} {Behavior} of a {Cyano}-{Functionalized} {Porphyrin} on {Cu}(111) and {Ag}(111): {From} {Molecular} {Wires} to {Ordered} {Supramolecular} {Two}-{Dimensional} {Aggregates}}, volume = {121}, year = {2017} } @article{faucris.267475647, abstract = {Using temperature-programmed desorption, adsorption energies of metallotetraphenylporphyrins were measured and used as a benchmark for dispersion-corrected density-functional theory calculations. Experimentally, simple Redhead analysis was used to extract monolayer adsorption energies for cobalt, zinc and magnesium 5,10,15,20-tetraphenyl porphyrin on MgO(100) thin films grown on Ag(100), where the prefactor for desorption was calculated by transition-state theory. Magnesium exhibits the highest experimental adsorption energy of 217 kJ/mol, while zinc and cobalt have adsorption energies of 193 and 186 kJ/mol, respectively. Using density-functional theory with a modified Grimme D3 scheme resulted in calculated adsorption energies of 209, 171 and 174 kJ/mol. The trend and even the absolute values of the experiment and the theory are in good agreement. Additionally, the calculations allow us to break down the different contributions to the adsorption energies, showing the interplay of van der Waals interactions, chemical bonds and deformation energies.}, author = {Wolfram, Alexander and Tariq, Quratulain and Fernández, Cynthia C. and Muth, Maximilian and Gurrath, Martin and Wechsler, Daniel and Franke, Matthias and Williams, Federico J. and Steinrück, Hans-Peter and Meyer, Bernd and Lytken, Ole}, doi = {10.1016/j.susc.2021.121979}, faupublication = {yes}, journal = {Surface Science}, keywords = {Adsorption energies; Dispersion-corrected density-functional theory; MgO(100); Porphyrins; Temperature-programmed desorption}, note = {CRIS-Team Scopus Importer:2021-12-24}, peerreviewed = {Yes}, title = {{Adsorption} energies of porphyrins on {MgO}(100): {An} experimental benchmark for dispersion-corrected density-functional theory}, volume = {717}, year = {2022} } @article{faucris.222393758, abstract = {Controlling the adsorption geometry of porphyrin molecules on titania surfaces is an important step in the rational design of molecular devices such as dye-sensitized solar cells. We employed X-ray Photoelectron Spectroscopy (XPS) and Near-Edge X-Ray-Absorption Fine Structure (NEXAFS) spectroscopy to determine the binding mode, the electronic structure and the adsorption geometry of carboxylic acid functionalized tetraphenylporphyrin molecules. Molecules with one (mono), two (cis and trans) and four (tetra) carboxylic acid anchoring groups were adsorbed on rutile TiO<inf>2</inf>(110). XPS shows that the iminic nitrogen atoms at the macrocycle center are partially protonated after adsorption, and that the degree of protonation increases with the number of –COOH functional groups in the molecule. NEXAFS measurements show that molecules with either one or two groups in cis configuration adsorb with the macrocycle tilted away from the surface. In contrast, molecules with two carboxylic-acid groups in trans configuration adsorb with what is probably a flat-lying, but distorted macrocycle. Finally, molecules with four carboxylic-acid groups show no linear dichroism, indicating an intermediate adsorption angle. Our results show how the number and position of the –COOH functional groups determine the molecular adsorption geometry.}, author = {Fernández, Cynthia C. and Wechsler, Daniel and Rocha, Tulio C.R. and Steinrück, Hans-Peter and Lytken, Ole and Williams, Federico J.}, doi = {10.1016/j.susc.2019.121462}, faupublication = {yes}, journal = {Surface Science}, keywords = {Adsorption geometry; Carboxylic acids; Near Edge X-Ray Absorption Fine Structure; Porphyrin molecules; Titanium oxide; X-ray photoelectron spectroscopy}, note = {CRIS-Team Scopus Importer:2019-07-16}, peerreviewed = {Yes}, title = {{Adsorption} geometry of carboxylic acid functionalized porphyrin molecules on {TiO2}(110)}, volume = {689}, year = {2019} } @article{faucris.120339164, abstract = {We report on sticking coefficient measurements for CO adsorption at 90 K on differently prepared Cr layers on Ru(0 0 0 1). Using a supersonic molecular beam we study initial and coverage-dependent sticking coefficients, S and S(&theta;), respectively, as function of the kinetic energy of the CO molecules. For a pseudomorphic Cr monolayer (prepared at 700 K), S decreases from 0.93 for low kinetic energies (0.09 eV) to 0.82 at 0.4 eV, and stays unchanged for higher kinetic energies up to 2.15 eV. In contrast, on a Cr/Ru surface alloy (for Cr deposition at 1000 K) S closely follows the behavior of clean Ru(0 0 0 1), decreasing from 0.93 to about 0.6 for 2.15 eV. The coverage-dependent sticking coefficients at low kinetic energies show pronounced precursor-mediated behavior, while for higher kinetic energies a Langmuir-like adsorption kinetics is found, which is most prominent for the Cr monolayer. &copy; 2003 Elsevier Science B.V. All rights reserved.}, author = {Denecke, Reinhard and Tränkenschuh, Barbara and Engelhardt, Martin Peter and Steinrück, Hans-Peter}, doi = {10.1016/S0039-6028(03)00170-5}, faupublication = {yes}, journal = {Surface Science}, pages = {173-178}, peerreviewed = {Yes}, title = {{Adsorption} kinetics of {CO} on {Cr}/{Ru} surfaces}, year = {2003} } @article{faucris.108278764, abstract = {The adsorption of cobalt (II) octaethylporphyrin (CoOEP) and 2H-octaethylporphyrin (2HOEP) on Ag(111) was investigated with scanning tunneling microscopy (STM) and photoelectron spectroscopy (XPS/UPS), in order to achieve a detailed mechanistic understanding of the surface chemical bond of coordinated metal ions. Previous studies of related systems, especially cobalt (II) tetraphenylporphyrin (CoTPP) on Ag(111), have revealed adsorptioninduced changes of the oxidation state of the Co ion and the appearance of a new valence state. These effects were attributed to a covalent interaction of the Co ion with the silver substrate. However, recent studies show that the porphyrin ligand of adsorbed CoTPP undergoes a pronounced saddle-shape distortion, which could alter the electronic structure and thus provide an alternative explanation for the new valence state previously attributed to the formation of a surface coordinative bond. With the octaethylporphyrins investigated here, which were found to adsorb in a flat, undistorted conformation on Ag(111), the effects of geometric distortion can be separated from those of the electronic interaction with the substrate. The CoOEP monolayer gives rise to an adsorption-induced shift of the Co 2p signal (-1.9 eV relative to the multilayer), a new valence state at 0.6 eV below the Fermi energy, and a work-function shift of -0.84eV (2HOEP: -0.44eV) relative to the clean surface. Comparison with data for the distorted CoTPP confirms the existence of a covalent ion-surface interaction that is insensitive to the conformation of the ligand. &copy; IOP Publishing Ltd and Deutsche Physikalische Gesellschaft.}, author = {Bai, Yun and Buchner, Florian and Kellner, Ina and Schmid, Martin and Vollnhals, Florian and Steinrück, Hans-Peter and Marbach, Hubertus and Gottfried, Michael}, doi = {10.1088/1367-2630/11/12/125004}, faupublication = {yes}, journal = {New Journal of Physics}, peerreviewed = {Yes}, title = {{Adsorption} of cobalt ({II}) {octaethyIporphyrin} and {2H}-octaethylporphyrin on {Ag}(111): {New} insight into the surface coordinative bond}, volume = {11}, year = {2009} } @article{faucris.108307364, abstract = {We studied the adsorption of CO on ultrathin Cr layers on Ru(0 0 0 1) as a function of Cr coverage and deposition temperature. The preparation of the Cr layers was characterized by Auger electron spectroscopy, low energy electron diffraction, and the subsequent CO adsorption itself. At 90 K Cr grows statistically on Ru(0 0 0 1). For Cr deposition at 700 K, a pseudomorphic monolayer is formed; thereafter Cr grows in three dimensional islands and the formation of a highly ordered bcc(1 1 0) Cr phase is observed. For Cr deposition at 1000 K we propose the formation of a stable surface alloy. Temperature programmed desorption of CO after dosing onto the Cr layers prepared at 700 and 1000 K indicates an enhanced reactivity of the layers towards CO dissociation upon heating as compared to Ru(0 0 0 1). In both cases a high temperature CO desorption state (above 700 K) is observed that is attributed to recombinative desorption of CO; its intensity increases up to a nominal Cr coverage of 1 ML. For the Cr layers prepared at 700 K, this state is observed already at the lowest Cr coverage studied (0.12 ML); for 1 ML Cr, 47% of the saturated CO layer decompose upon heating. For the Cr layers prepared at 1000 K (surface alloy) significant decomposition is observed only for Cr coverages larger than 0.5 ML; a maximum fraction of 18% of the saturated CO layer decomposes upon heating. Thus, the Cr layer prepared at 700 K is more reactive towards CO dissociation than the one prepared at 1000 K. &copy; 2002 Elsevier Science B.V. All rights reserved.}, author = {Engelhardt, Martin Peter and Fuhrmann, Thomas and Held, Georg and Denecke, Reinhard and Steinrück, Hans-Peter}, doi = {10.1016/S0039-6028(02)01664-3}, faupublication = {yes}, journal = {Surface Science}, pages = {107-116}, peerreviewed = {Yes}, title = {{Adsorption} of {CO} on ultrathin {Cr} layers on {Ru}(0 0 0 1)}, volume = {512}, year = {2002} } @article{faucris.326595737, abstract = {Using high-resolution synchrotron-radiation photoelectron spectroscopy and near-edge X-ray-absorption fine structure, we have investigated the adsorption of three phenylboronic acid derivatives on rutile TiO<inf>2</inf>(110) at 300-700 K: 4-acetylphenylboronic acid, 1,4-phenylenediboronic acid, and 2,4,6-triphenylboroxine. Both 4-acetylphenylboronic acid and 1,4-phenylenediboronic acid adsorb in a singly deprotonated monodentate configuration at 300 K, which converts to a fully deprotonated bidentate species at 550 K. 2,4,6-Triphenylboroxine undergoes a ring-opening reaction upon adsorption on the surface and forms the fully deprotonated bidentate species already at 300 K. In the case of 1,4-phenylenediboronic acid, the upward-pointing boronic-acid groups polymerize into boronic anhydride chains upon heating starting at 350 K. For 2,4,6-triphenylboroxine, we find a slow boron-carbon bond cleavage over a wide temperature range, resulting in a slow disappearance of the phenyl rings from the surface. For 4-acetylphenylboronic acid, we observe a loss of the carbonyl group at 500-550 K. In addition, we observe the formation of trigonal boron oxide (B<inf>2</inf>O<inf>3</inf>) for all three molecules at temperatures above 600 K.}, author = {Wolfram, Alexander and Muth, Maximilian and Williams, Federico J. and Mehl, Sascha and Tsud, Nataliya and Steinrück, Hans-Peter and Lytken, Ole}, doi = {10.1021/acs.jpcc.4c03264}, faupublication = {yes}, journal = {Journal of Physical Chemistry C}, note = {CRIS-Team Scopus Importer:2024-08-02}, peerreviewed = {Yes}, title = {{Adsorption} of {Phenylboronic} {Acid} {Derivatives} on {Rutile} {TiO2}(110)}, year = {2024} } @article{faucris.239063140, abstract = {Binding of functionalized organic molecules to oxide surfaces is an important step in the rational design of molecular devices. In the present investigation, we used synchrotron radiation photoelectron spectroscopy and near-edge X-ray absorption fine structure spectroscopy to determine the binding mode, electronic structure and adsorption geometry of phenylphosphonic acid (PPA) on TiO<inf>2</inf>(110)–(1 × 1). We found that PPA multilayers desorb below 380 K leaving a compact PPA monolayer adsorbed on the surface, which remains stable up to 780 K. In the 380–520 K temperature range, molecules are anchored to the surface via a single P–O–Ti covalent bond (monodentate configuration). Furthermore, the phenyl ring is tilted ~45° with respect to the surface plane and it either forms 45° or is randomly oriented with respect to [001] crystallographic direction. Raising the temperature above 520 K partially transforms the monodentate configuration to a mixed one- and twofold deprotonated bidentate binding mode, presumably after surface hydroxyl groups leave the surface as water molecules. This change in molecular binding does not alter the molecular electronic structure nor the adsorption geometry, which remain essentially unchanged.}, author = {Köbl, Julia and Wechsler, Daniel and Kataev, Elmar and Williams, Federico J. and Tsud, Nataliya and Franchi, Stefano and Steinrück, Hans-Peter and Lytken, Ole}, doi = {10.1016/j.susc.2020.121612}, faupublication = {yes}, journal = {Surface Science}, note = {CRIS-Team Scopus Importer:2020-06-05}, peerreviewed = {Yes}, title = {{Adsorption} of phenylphosphonic acid on rutile {TiO2}(110)}, volume = {698}, year = {2020} } @article{faucris.217473531, abstract = {We studied the adsorption geometry and bonding of mono- and tetraphosphonic-acid-functionalized tetraphenylporphyrin molecules on rutile TiO 2 (110) surfaces. The investigation was carried out by means of X-ray photoelectron spectroscopy and near edge X-ray absorption fine structure (NEXAFS) measurements. We found that the molecules bind covalently to the surface in a mixed monodentate and bidentate mode implying deprotonation of one or two phosphonate hydroxyl groups. Our NEXAFS data suggest that molecules containing one functional phosphonic acid group are on average tilted further away from the surface than molecules with four functional groups. The highest occupied electronic state of both molecules is in the band gap at 2.1 eV below the Fermi level. Our results demonstrate that the number of functional phosphonic acid groups determine the adsorption geometry of tetraphenylporphyrins.}, author = {Fernández, Cynthia C. and Wechsler, Daniel and Rocha, Tulio C.R. and Steinrück, Hans-Peter and Lytken, Ole and Williams, Federico J.}, doi = {10.1021/acs.jpcc.9b01019}, faupublication = {yes}, journal = {Journal of Physical Chemistry C}, note = {CRIS-Team Scopus Importer:2019-05-14}, peerreviewed = {Yes}, title = {{Adsorption} of {Phosphonic}-{Acid}-{Functionalized} {Porphyrin} {Molecules} on {TiO2}(110)}, year = {2019} } @book{faucris.112067164, abstract = {The adsorption of small molecules is a major step in surface reactions typically involved in heterogeneous catalysis. The detailed description of this process and the resulting adsorbate layer is essential in order to fully understand such systems. In this chapter, the adsorption process is described, and selected examples are discussed, demonstrating how this process can be investigated by spectroscopic methods, often combined with molecular beam techniques. Emphasis is put on stepped substrates as model systems for more complex catalytic particles. As a next step, the geometric structure of adsorbate layers is discussed, again including different investigation methods. Closely related to the geometric structure is the electronic structure of the adsorbed layers. Here, different examples are presented to illustrate how the orientation of adsorbed molecules and the resulting two-dimensional band structure can be derived using angle-resolved ultraviolet photoelectron spectroscopy.}, author = {Denecke, Reinhard and Steinrück, Hans-Peter}, doi = {10.1002/9783527680573.ch38}, faupublication = {yes}, isbn = {9783527411580}, keywords = {Adsorption; Band structure; Benzene; CO; Electronic structure; Ethylene; Geometric structure; Model system; Molecular beam techniques; Oxygen; Single crystal; Spectroscopy}, pages = {391-458}, peerreviewed = {unknown}, publisher = {Wiley Blackwell}, title = {{Adsorption} of ({Small}) {Molecules} on {Metals}}, volume = {5}, year = {2016} } @article{faucris.108460264, abstract = {From the measurement of the angular variation of the sticking coefficient and its change with beam energy one can conclude that adsorption of hydrogen on Ni(111) is an activated process whereas on Ni(110) no activation barrier exists. Adsorption on a stepped Ni(997) surface exhibits a pronounced minimum of the sticking coefficient at a gas temperature of 230 K. The activity of the steps for dissociation of H2 is confined to low gas temperatures. Detailed balancing is obeyed rigorously for adsorption and desorption on the Ni(111) and Ni(110) surface even at situations deviating from quasiequilibrium. On the stepped surface on the other hand establishing microscopic reversibility requires strict adherence to quasiequilibrium conditions. Permeation experiments lead to good agreement with low-temperature desorption on the Ni(111) surface but to complete disagreement with the data for the Ni(110) surface. As suggested by Comsa, permeating hydrogen in some cases seems to originate from a subsurface location rather than from an adsorbed state. Besides a small effect at low temperatures on the Ni(997) and Ni(110) surfaces no isotope effects for H2 and D2 are detected. &copy; 1985 The American Physical Society.}, author = {Steinrück, Hans-Peter and Luger, M. and Winkler, A. and Rendulic, K.D.}, doi = {10.1103/PhysRevB.32.5032}, faupublication = {no}, journal = {Physical Review B}, pages = {5032-5037}, peerreviewed = {Yes}, title = {{Adsorption} probabilities of {H2} and {D2} on various flat and stepped nickel surfaces}, volume = {32}, year = {1985} } @article{faucris.113343164, abstract = {We have determined the sticking probability of hydrogen and deuterium on a stepped nickel surface at different adsorption angles and for different surface and gas temperatures. The initial sticking coefficient shows a highly asymmetric behavior with respect to the surface normal; hydrogen molecules at room temperature impinging in the &#39;step-up&#39; direction have a considerably higher sticking probability than the &#39;step-down&#39; direction. This behavior is more pronounced for lower gas temperatures (T equals 150 K) and almost vanishes for higher gas temperatures (T equals 900 K). Blocking the active step sites with oxygen reduces the asymmetric adsorption behavior yielding an angular variation similar to the adsorption on a flat Ni(111) surface. The influence of the surface temperature on the sticking coefficient is much less pronounced in the experimentally accessible region (150-300 K). In the behavior of hydrogen and deuterium there are no prominent differences.}, author = {Karner, H. and Luger, M. and Steinrück, Hans-Peter and Rendulic, K.D. and Winkler, A.}, doi = {10.1016/0042-207X(87)90145-X}, faupublication = {no}, journal = {Vacuum}, peerreviewed = {Yes}, title = {{Adsorption} {Properties} of {Stepped} {Surfaces}.}, volume = {37}, year = {1985} } @article{faucris.110876744, abstract = {Using a combination of LEED, high-resolution XPS, XSW, and NEXAFS, we have studied the adsorption of cobalt(II) 5,10,15,20-tetraphenylporphyrin (CoTPP) on Ag(100) at 300 K. In agreement with previous studies on Ag(111), we find a charge transfer from the silver surface to the porphyrin molecule, reducing the metal center. At high coverages we observe a square-shaped 1.41 X 1.41 nm(2) adsorption structure, which becomes more open at lower coverages. Because of the superior energy resolution of the Diamond i09 beamline, we are able to resolve a low binding-energy shoulder in the C 1s spectrum, originating from the lower carbon atoms in the rotated phenyl rings. This is confirmed by XSW measurements, which also gives the adsorption heights of the other atoms in the molecule. In addition, the XSW and complementary NEXAFS measurements yield information about the rotation of the phenyl rings and the deformation of the macrocycle.}, author = {Wechsler, Daniel and Franke, Matthias and Tariq, Quratulain and Zhang, Liang and Lee, Tien-Lin and Thakur, Pardeep Kumar and Tsud, Nataliya and Bercha, Sofiia and Prince, Kevin Charles and Steinrück, Hans-Peter and Lytken, Ole}, doi = {10.1021/acs.jpcc.7b00518}, faupublication = {yes}, journal = {Journal of Physical Chemistry C}, pages = {5667-5674}, peerreviewed = {Yes}, title = {{Adsorption} {Structure} of {Cobalt} {Tetraphenylporphyrin} on {Ag}(100)}, volume = {121}, year = {2017} } @article{faucris.265504627, abstract = {We have studied the adsorption, wetting, growth, and thermal evolution of the protic IL diethylmethylammonium trifluoromethanesulfonate ([dema][TfO]) on Au(111) and Ag(111). Ultrathin films were deposited at room temperature (RT) and at 90 K, and were characterized in situ by angle-resolved X-ray photoelectron spectroscopy. For both surfaces, we observe that independent of temperature, initially, a closed 2D wetting layer forms. While the film thickness does not increase past this wetting layer at RT, at 200 K and below, "moderate"3D island growth occurs on top of the wetting layer. Upon heating, on Au(111), the [dema][TfO] multilayers desorb at 292 K, leaving an intact [dema][TfO] wetting layer, which desorbs intact at 348 K. The behavior on Ag(111) is much more complex. Upon heating [dema][TfO] deposited at 90 K, the [dema]+ cations deprotonate in two steps at 185 and 305 K, yielding H[TfO] and volatile [dema]0. At 355 K, the formed H[TfO] wetting layer partly desorbs (∼50%) and partly decomposes to form an F-containing surface species, which is stable up to 570 K.}, author = {Massicot, Stephen and Sasaki, Tomoya and Lexow, Matthias and Shin, Sunghwan and Maier, Florian and Kuwabata, Susumu and Steinrück, Hans-Peter}, doi = {10.1021/acs.langmuir.1c01823}, faupublication = {yes}, journal = {Langmuir}, note = {CRIS-Team Scopus Importer:2021-10-29}, pages = {11552-11560}, peerreviewed = {Yes}, title = {{Adsorption}, {Wetting}, {Growth}, and {Thermal} {Stability} of the {Protic} {Ionic} {Liquid} {Diethylmethylammonium} {Trifluoromethanesulfonate} on {Ag}(111) and {Au}(111)}, volume = {37}, year = {2021} } @article{faucris.224744544, author = {Wu, Mingjian and Grabau, Mathias and Taccardi, Nicola and Papp, Christian and Steinrück, Hans-Peter and Wasserscheid, Peter and Spiecker, Erdmann}, doi = {10.1017/S1431927619010122}, faupublication = {yes}, journal = {Microscopy and Microanalysis}, pages = {1878-1879}, peerreviewed = {Yes}, title = {{Advanced} and {In}-{Situ} {Electron} {Microscopy} {Investigation} of {Phase} {Composition} and {Phase} {Transformation} in {Ga}-{Rh} {Liquid} {Metal} {Catalysts}}, volume = {25}, year = {2019} } @article{faucris.117429664, abstract = {Memory devices are a key technology of our era and one of the constant challenges is the reduction of their power consumption. Herein, we demonstrate that graphene oxide with very few defects, that is, about 1 nm thin oxo-functionalized graphene derivative, can be used in memory devices operating at 3 V. A memory device stores charges in the material of the active channel. Thereby, writing and erasing information can be performed at low voltage, facilitating low power consumption. To enable operation at low voltage, a novel synthetic approach is necessary. We find that the selective non-covalent electrostatic functionalization of mainly organosulfate ions is possible with dodecylammonium. This functionalization allows the non-covalent coating of flakes with a polystyrene-derivative as nm-thin dielectric medium. The resulting polymer-wrapped composite has a height of about 5 nm. We find that the thin coating of a few nm is mandatory to make the memory device work at low voltage. Furthermore, a self-assembled monolayer of an imidazolium derivative further enhances the function of the memory device. The prepared composite materials are characterized by state-of-the-art analysis including solid state nuclear magnetic resonance spectroscopy and thermogravimetric analysis coupled with gas chromatography, mass spectroscopy or infrared spectroscopy. Reference experiments prove the importance of the controlled synthesis to enable the function of the memory device.}, author = {Wang, Zhenxing and Eigler, Siegfried and Ishii, Yoshitaka and Hu, Yichen and Papp, Christian and Lytken, Ole and Steinrück, Hans-Peter and Halik, Marcus}, doi = {10.1039/C5TC01861G}, faupublication = {yes}, journal = {Journal of Materials Chemistry C}, month = {Jan}, pages = {8595-8604}, peerreviewed = {Yes}, title = {{A} facile approach to synthesize an oxo-functionalized graphene/polymer composite for low-voltage operating memory devices}, url = {http://pubs.rsc.org/en/Content/ArticleLanding/2015/TC/C5TC01861G#!divAbstract}, volume = {3}, year = {2015} } @article{faucris.120339384, abstract = {Propene uptake at 105 was experimentally studied. A single molecular adsorption state was observed. Changes in methyl group peak binding energy revealed adsorbate-adsorbate interactions and a dispersed phase growth mechanism. A notable result is the observation that a new surface species evolves above 200 K from decomposition of di-&sigma;-bonded propene.}, author = {Whelan, Caroline and Neubauer, Ralf and Borgmann, Dieter and Denecke, Reinhard and Steinrück, Hans-Peter}, doi = {10.1063/1.1406502}, faupublication = {yes}, journal = {Journal of Chemical Physics}, pages = {8133-8140}, peerreviewed = {Yes}, title = {{A} fast x-ray photoelectron spectroscopy study of the adsorption and temperature-dependent decomposition of propene on {Ni}(100)}, volume = {115}, year = {2001} } @article{faucris.119560584, abstract = {A major bottleneck delaying the further commercialization of thin-film solar cells based on hybrid organohalide lead perovskites is the interface losses in state-of-the-art devices. We present a generic interface architecture that combines solution-processed, reliable, and cost-efficient hole-transporting materials, without compromising efficiency, stability or scalability of perovskite solar cells. Tantalum doped tungsten oxide (Ta-WO_x)/conjugated polymer multilayers offer a surprisingly small interface barrier and form quasi-ohmic contacts universally with various scalable conjugated polymers. Using a simple regular planar architecture device, Ta-WO_x doped interface-based perovskite solar cells achieve maximum efficiencies of 21.2% and combined with over 1000 hours of light stability based on a self-assembled monolayer. By eliminating additional ionic dopants, these findings open up the whole class of organics as scalable hole-transporting materials for perovskite solar cell}, author = {Hou, Yi and Du, Xiaoyan and Scheiner, Simon and McMeekin, David P. and Wang, Zhiping and Li, Ning and Killian, Manuela and Chen, Haiwei and Richter, Moses and Levchuk, Ievgen and Schrenker, Nadine and Spiecker, Erdmann and Stubhan, Tobias and Luechinger, Norman A. and Hirsch, Andreas and Schmuki, Patrik and Steinrück, Hans-Peter and Fink, Rainer and Halik, Marcus and Snaith, Henry J. and Brabec, Christoph}, doi = {10.1126/science.aao5561}, faupublication = {yes}, journal = {Science}, pages = {1-9}, peerreviewed = {Yes}, title = {{A} generic interface to reduce the efficiency-stability-cost gap of perovskite solar cells}, year = {2017} } @article{faucris.272839249, abstract = {The adsorption and thermal evolution of ethylene on Rh(1 1 1) were investigated by state-of-the-art surface science techniques. Synchrotron radiation-based high-resolution X-ray photoelectron spectroscopy (XPS) and temperature-programmed XPS allowed for the examination of the adsorption process and the reaction pathway of ethylene on Rh(1 1 1). At 140 K, ethylene adsorbs molecularly in a symmetrical geometry. The reaction intermediates formed upon heating were identified by the vibrational fine structure of XPS. At approximately 200 K, ethylidyne emerges, as expected from literature. Above 350 K, we observe the evolution of methylidyne. Simultaneously, decomposition to carbides sets in, which is completed at ∼ 460 K.}, author = {Freiberger, Eva Marie and Düll, Fabian and Wichmann, Christoph and Bauer, Udo and Steinrück, Hans-Peter and Papp, Christian}, doi = {10.1016/j.cplett.2022.139595}, faupublication = {yes}, journal = {Chemical Physics Letters}, keywords = {Coking; Ethylene; Ethylidyne; High-resolution X-ray photoelectron spectroscopy; Methylidyne; Rhodium; Unsaturated hydrocarbons; Vibrational fine structure}, note = {CRIS-Team Scopus Importer:2022-04-14}, peerreviewed = {Yes}, title = {{A} high-resolution {X}-ray photoelectron spectroscopy study on the adsorption and reaction of ethylene on {Rh}(1 1 1)}, volume = {797}, year = {2022} } @article{faucris.210451813, abstract = {Together with borazine, ammonia borane is a prominent precursor molecule for the formation of hexagonal boron nitride, which is of high interest as a 2D-material and graphene analog. Ammonia borane is also a possible solid hydrogen carrier for renewable energies with high storage density. Using X-ray photoelectron spectroscopy and temperature-programmed desorption, we investigated low-temperature adsorption and dehydrogenation during heating of borazine and ammonia borane on Ni(111) to form h-BN. For borazine, we observe the formation of disordered boron nitride above 300 K, which starts to form hexagonal boron nitride above 600 K. Ammonia borane shows multiple dehydrogenation steps at the boron and nitrogen atoms up to 300 K. This results in various BHxNHy species, including borazine-like intermediates, before the formation of disordered boron nitride and finally hexagonal boron nitride, analogous to the borazine decomposition. Published by AIP Publishing.}, author = {Bachmann, Philipp and Düll, Fabian and Späth, Florian and Bauer, Udo and Steinrück, Hans-Peter and Papp, Christian}, doi = {10.1063/1.5051595}, faupublication = {yes}, journal = {Journal of Chemical Physics}, peerreviewed = {Yes}, title = {{A} {HR}-{XPS} study of the formation of h-{BN} on {Ni}(111) from the two precursors, ammonia borane and borazine}, volume = {149}, year = {2018} } @article{faucris.114451964, abstract = {The concept of liquid organic hydrogen carriers (LOHC) holds the potential for large scale chemical storage of hydrogen at ambient conditions. Herein, we compare the dehydrogenation and decomposition of three alkylated carbazole-based LOHCs, dodecahydro-N-ethylcarbazole (H-NEC), dodecahydro-N- propylcarbazole (H-NPC), and dodecahydro-N-butylcarbazole (H -NBC), on Pt(111) and on AlO-supported Pt nanoparticles. We follow the thermal evolution of these systems quantitatively by in situ high-resolution X-ray photoelectron spectroscopy. We show that on Pt(111) the relevant reaction steps are not affected by the different alkyl substituents: for all LOHCs, stepwise dehydrogenation to NEC, NPC, and NBC is followed by cleavage of the C-N bond of the alkyl chain starting at 380-390 K. On Pt/AlO, we discern dealkylation on defect sites already at 350 K, and on ordered, (111)-like facets at 390 K. The dealkylation process at the defects is most pronounced for NEC and least pronounced for NBC. &copy; 2014 AIP Publishing LLC.}, author = {Gleichweit, Christoph and Amende, Maximilian and Bauer, Udo and Schernich, Stefan and Höfert, Oliver and Lorenz, Michael Peter Andreas and Zhao, Wei and Müller, Michael and Koch, Marcus and Bachmann, Philipp and Wasserscheid, Peter and Libuda, Jörg and Steinrück, Hans-Peter and Papp, Christian}, doi = {10.1063/1.4875921}, faupublication = {yes}, journal = {Journal of Chemical Physics}, pages = {204711}, peerreviewed = {Yes}, title = {{Alkyl} chain length-dependent surface reaction of dodecahydro-{N}-alkylcarbazoles on {Pt} model catalysts}, volume = {140}, year = {2014} } @article{faucris.118990344, author = {Steinrück, Hans-Peter and Pache, T. and Huber, W.}, doi = {10.1088/0031-8949/41/1/043}, faupublication = {no}, journal = {Physica Scripta}, pages = {177-180}, peerreviewed = {Yes}, title = {{A} {LOW} {COVERAGE} {STUDY} {OF} {NO} {ON} {NI}(111) {BY} {ANGLE} {RESOLVED} {AUGER}-{ELECTRON} {SPECTROSCOPY} {AT} {RESONANCE} {EXCITATION}}, volume = {41}, year = {1990} } @article{faucris.113318964, abstract = {Using molecular beam techniques we have investigated the initial dissociative sticking probability for ethane on a reconstructed Ir(110)-(1 &times; 2) surface. At kinetic energies below 15 kcal mol the probability of activation at zero surface coverage, S, is constant at about 0.03. With increasing beam energy S increases nearly linearly to a value of 0.40 at an energy near 40 kcal mol. Variation of surface temperature in the range 300 &le; T &le; 1400 K does not influence the dependence of S on kinetic energy. &copy; 1986.}, author = {Steinrück, Hans-Peter and Hamza, Alex and Madix, R.J.}, faupublication = {no}, journal = {Surface Science}, peerreviewed = {Yes}, title = {{A} molecular beam investigation on the kinetic energy dependence of the activation of ethane on the reconstructed {Ir}(110)-(1 × 2) surface}, url = {https://www.scopus.com/record/display.uri?eid=2-s2.0-4243647356&origin=inward}, volume = {173}, year = {1986} } @article{faucris.108487764, abstract = {We have investigated the sticking coefficient of CO on Ru(0001), a pseudomorphic Cu monolayer on Ru(0001), and a fully relaxed Cu(111) multilayer as function of kinetic energy, surface coverage, and surface temperature. At a low kinetic energy of 0.09 eV, the initial sticking coefficients, S , on these surfaces are determined to be 0.92, 0.96 and 0.87, respectively. In all cases, a decrease of S with increasing beam energy was observed, yielding values of 0.58, 0.14 and 0.07, respectively, at a kinetic energy of &sim;2.0 eV. For all three surfaces the coverage dependent sticking coefficients, S(&Theta;), display very characteristic behavior at low kinetic energies: S(&Theta;) remains more or less constant up to coverages close to saturation, indicative of precursor adsorption kinetics. However, characteristic minima at intermediate coverages are observed, which are correlated to the formation of well ordered adsorbate phases. For high kinetic energies we observe a transition towards a linear decrease of S(&Theta;) for Ru(0001). In contrast, for the pseudomorphic Cu monolayer and for Cu(111) we find an increase in the sticking coefficients at low coverages, followed by a decrease close to saturation. This behavior is attributed to adsorbate assisted sticking, that is, to a higher sticking coefficient on adsorbate covered regions than on the bare surface. The comparison between the pseudomorphic monolayer and Cu(111) reveals that the CO bond strength to the former is larger by &sim;40%. The initial sticking coefficients for both surfaces are very similar at low kinetic energies; at high kinetic energies, S for the pseudomorphic Cu monolayer is, however, larger by a factor of two. &copy; 1999 Elsevier Science B.V. All rights reserved.}, author = {Kneitz, Stefan and Gemeinhardt, J. and Steinrück, Hans-Peter}, doi = {10.1016/S0039-6028(99)00773-6}, faupublication = {yes}, journal = {Surface Science}, pages = {307-320}, peerreviewed = {Yes}, title = {{A} molecular beam study of the adsorption dynamics of {CO} on {Ru}(0001), {Cu}(111) and a pseudomorphic {Cu} monolayer on {Ru}(0001)}, volume = {440}, year = {1999} } @article{faucris.120346424, abstract = {The adsorption of ethylene oxide on Ni(110) has been studied by TPD, work function measurements, LEED, XPS, and angle resolved UPS using linearly polarized synchrotron radiation. At temperatures below 100 K ethylene oxide adsorbs in molecular form on Ni(110) with a saturation coverage of &sim; 0.5 ML (1 ML = 1 molecule Ni atom). Upon heating, molecular desorption occurs in a broad peak ranging from &sim; 110 to 240 K; there is no indication of dissociation, as concluded from TPD and XPS. At saturation a sharp c(2 &times; 2) LEED pattern is observed. From ARUPS we deduce that the C rotation axis of the molecule is tilted away from the surface normal and that the mirror planes of the molecule do not coincide with the substrate mirror planes, independent of coverage. &copy; 1993.}, author = {Weinelt, M. and Zebisch, P. and Steinrück, Hans-Peter}, doi = {10.1016/0039-6028(93)90825-5}, faupublication = {no}, journal = {Surface Science}, pages = {471-475}, peerreviewed = {Yes}, title = {{A} multimethod-investigation of the adsorption of ethylene oxide on {Ni}(110)}, year = {1993} } @article{faucris.120345984, abstract = {A collimator system using four apertures is used to select a narrow beam of ∓ 2&deg; opening from a single crystal sample. Since the apertures only &quot;see&quot; a small strip of the sample surface, signals from the edges of the crystal are eliminated. Detector is an ion gauge located off the beam axis to guarantee energy independence of the detected signals. A large number of measurements for varying coverage, different crystal orientations and different azimuth positions of the sample are described for the system H/Ni and CO/Ni. &copy; 1985.}, author = {Steinrück, Hans-Peter and Winkler, A. and Rendulic, K.D.}, faupublication = {no}, journal = {Surface Science}, pages = {323-327}, peerreviewed = {Yes}, title = {{An} accurate technique to measure angle-resolved flash desorption spectra}, url = {https://www.scopus.com/record/display.uri?eid=2-s2.0-0038704411&origin=inward}, year = {1985} } @article{faucris.269950796, abstract = {Carboxylic acids are often used to anchor large organic molecules to oxide surfaces. To understand the mechanism of this anchoring we have studied the temperature and coverage-dependent adsorption and reactions of phthalic acid on MgO(100) by a combination of X-ray photoelectron spectroscopy, near-edge X-ray absorption, UV photoelectron spectroscopy and density-functional theory. At 110 K, phthalic acid partly deprotonates on MgO(100) at low coverage and forms a dicarboxylate species. At higher coverage, the fraction of intact phthalic acid increases to a larger extent than that of the deprotonated species. Subsequent annealing of these mixed structures results in the full conversion of the remaining intact acid groups to carboxylate, that is, doubly deprotonated phthalic acid, at 250 K. Depending on coverage, the carboxylate-bonded species remain stable up to 500 – 600 K. Above this temperature, the molecules decompose and desorb as fragments, leaving only a small carbon residue behind on the surface.}, author = {Kataev, Elmar and Fromm, Lukas and Tariq, Quratulain and Wechsler, Daniel and Williams, Federico J. and Tsud, Nataliya and Franchi, Stefano and Steinrück, Hans-Peter and Görling, Andreas and Lytken, Ole}, doi = {10.1016/j.susc.2021.122007}, faupublication = {yes}, journal = {Surface Science}, keywords = {Magnesium oxide; Organic thin films; Phthalic acid; X-ray photoelectron spectroscopy}, note = {CRIS-Team Scopus Importer:2022-02-25}, peerreviewed = {Yes}, title = {{Anchoring} of phthalic acid on {MgO}(100)}, volume = {720}, year = {2022} } @article{faucris.118768144, abstract = {Asymmetric peak profiles for the application in spectroscopy can be obtained in a simple way by substituting the usually constant full width at half maximum parameter in Pseudo-Voigt functions with an energy-dependent expression, for instance of sigmoidal shape. While this approach has been successfully applied to vibrational spectra, we find that the resulting curves are less suitable for least-squares fits of X-ray photoelectron spectroscopy (XPS) data. However, if one additionally allows a variable displacement of the sigmoidal step relative to the peak, excellent fitting results can be obtained. We demonstrate the applicability of our extended approach on several inherently asymmetric XPS lines, i.e. the C 1s signal of graphite and CH/Pd(100), the 3d-3d doublet of palladium, and the 4f-4f doublet of platinum. Comparison of the corresponding fit results with the results obtained by the application of more elaborate, theory-based line profiles (Doniach-&Scaron;unjić and Mahan functions) shows that the modified Pseudo-Voigt function gives practically identical results in terms of peak shape and area, while requiring much less computational effort since no convolution procedures are required for its calculation. Thus, this function is most suitable for application in one of the following situations: (i) the peak shape of a given signal is known but cannot be calculated with ease, and (ii) the theoretical peak shape is not (yet) known, however, one wants to perform a first quantitative screening of the data at issue. &copy; 2014 John Wiley &amp; Sons, Ltd.}, author = {Schmid, Martin and Steinrück, Hans-Peter and Gottfried, J. Michael}, doi = {10.1002/sia.5521}, faupublication = {yes}, journal = {Surface and Interface Analysis}, peerreviewed = {Yes}, title = {{A} new asymmetric {Pseudo}-{Voigt} function for more efficient fitting of {XPS} lines}, year = {2014} } @article{faucris.122058904, author = {Schmid, Martin and Steinrück, Hans-Peter and Gottfried, Michael}, doi = {10.1002/sia.5847}, faupublication = {yes}, journal = {Surface and Interface Analysis}, pages = {1080-1080}, peerreviewed = {Yes}, title = {{A} new asymmetric {Pseudo}-{Voigt} function for more efficient fitting of {XPS} lines (vol 46, pg 505, 2014)}, volume = {47}, year = {2015} } @inproceedings{faucris.110363704, author = {Steinrück, Hans-Peter and Rendulic, K.D. and Winkler, A.}, booktitle = {Proc. Symposium on Surface Science}, faupublication = {no}, note = {UnivIS-Import:2015-04-16:Pub.1985.nat.dchph.lpc2.anexpe}, pages = {101-106}, title = {{An} experimental investigation of detailed balancing for the systems {H2}/nickel and {CO}/nickel}, venue = {Obertraun}, year = {1985} } @inproceedings{faucris.108692364, author = {Steinrück, Hans-Peter and Rendulic, K.D. and Winkler, A.}, booktitle = {Proceeding on Surface Science 3S'85}, editor = {G. Betz, H. Störi, W. Husinsky, P. Varga,}, faupublication = {no}, pages = {101-106}, publisher = {Proceeding Symposium on Surface Science}, series = {Proceeding Symposium on Surface Science 3S'85 (Obertraun)}, title = {{An} experimental investigation of detailed balancing for the systems {H2}/nickel und {CO}/nickel}, venue = {Obertraun}, year = {1985} } @article{faucris.120420124, abstract = {Angle-resolved UV photoelectron spectroscopy is used to investigate the electronic structure and bonding of adsorbed hydrocarbons, the orientation and symmetry of the adsorbate on the surface, the influence of lateral interactions, and the formation of two-dimensional adsorbate band structures. Several examples of simple hydrocarbon molecules such as benzene, ethylene and acetylene adsorbed on Ni(110), Ni(111), Ru(001) and the reconstructed Pt(110)1x2 surface are presented. The experimental studies are accompanied by theoretical calculation. In addition some special aspects of the photoemission process, namely the photoionization cross section and vibronic coupling, are discussed.}, author = {Steinrück, Hans-Peter}, doi = {10.1088/0953-8984/8/36/003}, faupublication = {no}, journal = {Journal of Physics: Condensed Matter}, pages = {6465-6509}, peerreviewed = {Yes}, title = {{Angle}-resolved photoemission studies of adsorbed hydrocarbons}, volume = {8}, year = {1996} } @article{faucris.107793664, abstract = {Flux measurements for desorption angles -60 degrees}, author = {Steinrück, Hans-Peter and Winkler, A. and Rendulic, K.D.}, doi = {10.1088/0022-3719/17/11/003}, faupublication = {no}, journal = {Journal of Physics. C. Solid State Physics}, peerreviewed = {unknown}, title = {{Angle}-resolved thermal desorption spectra for {CO} and {H2} from {Ni}(111), {Ni}(110) and polycrystalline nickel}, volume = {17}, year = {1984} } @article{faucris.120951644, author = {Steinrück, Hans-Peter}, faupublication = {yes}, journal = {Vacuum}, pages = {715-731}, peerreviewed = {Yes}, title = {{Angle}-resolved {UV}-photoelectron spectroscopy}, url = {https://www.scopus.com/record/display.uri?eid=2-s2.0-0028445968&origin=inward}, volume = {45}, year = {1994} } @book{faucris.114243184, author = {Steinrück, Hans-Peter}, editor = {J.M. Walls, R. Smith}, faupublication = {no}, pages = {67-83}, publisher = {Pergamon}, series = {Surface Science Techniques}, title = {{Angle}-resolved {UV}-photoelectron spectroscopy}, year = {1994} } @inproceedings{faucris.120382064, author = {Steinrück, Hans-Peter}, booktitle = {Proc. Symposium on Surface Science 3S'91}, editor = {P. Varga, G. Betz}, faupublication = {no}, pages = {67-74}, publisher = {Proceeding Symposium on Surface Science}, series = {Proceeding Symposium on Surface Science 3S'91 (Obertraun)}, title = {{Angle} resolved {UV}-photoelectron spectroscopy of adsorbed molecules}, venue = {Obertraun}, year = {1991} } @article{faucris.120346644, abstract = {A review of results obtained by Angle-Resolved UV-Photoelectron Spectroscopy (ARUPS) using linearly polarized synchrotron radiation is presented for two model systems, ethylene/Ni and benzene/Ni. It is shown that for these systems detailed conclusions concerning adsorbate/substrate and adsorbate/adsorbate interactions can be derived from ARUPS spectra using symmetry selection rules, and in combination with model calculations. In particular, electronic structure, bonding, orientation and symmetry of the adsorbates in dilute and saturated layers will be discussed. It is shown that at high adsorbate coverages lateral interactions in the adsorbate layer play a dominant role. Steric effects in densely packed layers can lead to a reorientation of the molecules as compared to the orientation of the single molecules. The ARUPS spectra of well ordered, densely packed layers exhibit significant (up to 2 eV) dispersion of the various adsorbate bands and allow detailed conclusions on two-dimensional adsorbate band structures. &copy; 1994 Springer-Verlag.}, author = {Steinrück, Hans-Peter}, doi = {10.1007/BF00348269}, faupublication = {no}, journal = {Applied Physics A: Solids and Surfaces}, pages = {517-529}, peerreviewed = {unknown}, title = {{Angle}-resolved {UV} photoelectron spectroscopy of ethylene and benzene on nickel}, volume = {59}, year = {1994} } @article{faucris.120339604, abstract = {Making use of the high intensity and resolution of synchrotron radiation at MAX-II (Sweden) we studied the dehydrogenation reaction of methanol on Ni(1 0 0) as a function of temperature by core level photoelectron spectroscopy. The temperature was increased linearly from 105 to 425 K with a heating rate of 0.06 K s. Measurement times of 60 s per C 1s spectrum allowed the dehydrogenation reaction to be monitored in situ. The different binding energies of the core level characteristic of different adsorbed species are reported. After exposure at 105 K, the C 1s spectra exhibit two peaks, representing methanol in multilayer and monolayer states. Above 160 K the multilayer is completely desorbed and methanol from the monolayer starts to dehydrogenate to form a methoxy species which decomposes above 240 K to carbon monoxide adsorbed in the bridge site. The onset of the on-top site occupation is observed at 270 K. The data suggests conversion from bridge to on-top site CO around 290 K. Our results show good agreement with literature values from temperature programmed desorption and Fourier transform infra-red experiments and provide new information in the form of quantitative data on the decomposition pathway of methanol adsorbed on Ni(1 0 0). &copy; 2002 Elsevier Science B.V. All rights reserved.}, author = {Neubauer, Ralf and Whelan, Caroline and Denecke, Reinhard and Steinrück, Hans-Peter}, doi = {10.1016/S0039-6028(02)01359-6}, faupublication = {yes}, journal = {Surface Science}, pages = {832-837}, peerreviewed = {Yes}, title = {{An} in situ photoemission study of the dehydrogenation reaction of methanol on {Ni}(1 0 0)}, year = {2002} } @article{faucris.206526627, author = {Lexow, Matthias and Heller, Bettina and Maier, Florian and Steinrück, Hans-Peter}, doi = {10.1002/cphc.201800773}, faupublication = {yes}, journal = {ChemPhysChem}, pages = {2978-2984}, peerreviewed = {Yes}, title = {{Anion} {Exchange} at the {Liquid}/{Solid} {Interface} of {Ultrathin} {Ionic} {Liquid} {Films} on {Ag}(111)}, volume = {19}, year = {2018} } @article{faucris.108310004, abstract = {We have investigated the growth of Cr on Ru(0 0 0 1) using scanning tunneling microscopy (STM). In the submonolayer regime (&theta; = 0.25 ML) monatomically high islands are formed at 300 K, accompanied by step decoration. The island density decreases upon heating to 700 K. Small amounts of Cr are incorporated in the Ru substrate at this temperature. For higher Cr coverages (2 ML), three-dimensional growth is observed at 300 K. Annealing this Cr layer to 500 and 700 K leads to the formation of Cr islands (4-5 layers high) with an elongated shape and bcc(1 1 0) structure with a pseudomorphic Cr monolayer covering the remaining substrate. As shown by atomically resolved images, the Cr bcc(1 1 0) islands have Kurdjumov-Sachs orientation with respect to the Ru(0 0 0 1) substrate. After annealing at 1000 K, the formation of a hexagonal, chemically disordered CrRu alloy is observed, in agreement with a previous study [Engelhardt et al., Surf. Sci. 512 (2002) 107]. The room-temperature STM investigation of CO adsorption on the CrRu alloy with approx. 34% Cr in the first layer shows that adsorbed molecular CO resides only on Ru atoms, not on Cr, mostly in an on-top geometry. The CO occupation of Ru sites increases slightly with the number of neighbouring Cr atoms, indicating a weak ligand effect. We also find indications that the few threefold hollow sites surrounded by three Cr atoms become occupied by atomic C or O, due to dissociation of a small fraction of the adsorbed CO molecules; thus, we cannot unambiguously determine whether molecular CO can bind to these threefold sites at room temperature. &copy; 2005 Elsevier B.V. All rights reserved.}, author = {Engelhardt, Martin Peter and Schmid, M. and Biedermann, A. and Denecke, Reinhard and Steinrück, Hans-Peter and Varga, P.}, doi = {10.1016/j.susc.2005.01.022}, faupublication = {yes}, journal = {Surface Science}, pages = {124-135}, peerreviewed = {Yes}, title = {{An} {STM} study of growth and alloying of {Cr} on {Ru}(0 0 0 1) and {CO} adsorption on the alloy}, volume = {578}, year = {2005} } @article{faucris.120347744, abstract = {We demonstrate that temperature programmed desorption (TPD) of argon is a sensitive and non-destructive probe to study the properties of an underlying substrate: the desorption temperatures of the first argon layer from the clean Ni(111) surface, the saturated chemisorbed benzene layer, the first physisorbed benzene layer (on top of chemisorbed benzene) and thicker physisorbed benzene layers on Ni(111) are determined to 39.0, 43.5, 36.5 and 30-32 K, respectively. We have applied argon desorption to investigate the initial growth behavior of physisorbed benzene layers on top of the chemisorbed (&radic;7&times;&radic;7)R19.1&deg; benzene layer on Ni(111): the argon TPD spectra show that the growth mode of the first physisorbed benzene layers strongly depends on adsorption temperature and on the number of defects in the chemisorbed layer.}, author = {Stichler, M. and Zebisch, P. and Weinelt, M. and Steinrück, Hans-Peter}, doi = {10.1016/0039-6028(95)01036-X}, faupublication = {no}, journal = {Surface Science}, pages = {370-378}, peerreviewed = {Yes}, title = {{Argon} desorption as a tool to study the growth of molecular layers}, volume = {348}, year = {1996} } @article{faucris.108486444, abstract = {We have designed a simple helium scattering apparatus for gas-surface scattering experiments. The effusive source is a glass multicapillary array, operated at large Knudsen numbers which produces a highly collimated thermal He beam (FWHM&asymp;3&deg;) with a Maxwellian velocity distribution. The detector is a Bayard Alpert ionization gauge, mounted in a tube that is separated from the main UHV chamber via a second multicapillary array. This setup allows one to select only those He atoms that are reflected by the sample in the specular direction and thus to measure the reflectivity of the surface. Examples of its performance are presented for the adsorption of CO on Ru(001), and for thermal annealing of a Ru(001) surface sputtered with argon ions at different energies.}, author = {Maier, Florian and Kneitz, Stefan and Koschel, Herbert and Steinrück, Hans-Peter}, faupublication = {no}, journal = {Surface Science}, pages = {1101-1105}, peerreviewed = {Yes}, title = {{A} simple design for a helium scattering apparatus}, url = {https://www.scopus.com/record/display.uri?eid=2-s2.0-0031121802&origin=inward}, year = {1997} } @article{faucris.108311104, abstract = {Using time-dependent high-resolution x-ray photoelectron spectroscopy at BESSY II, the adsorption and desorption processes of CO on stepped Pt (355) =Pt [5 (111) &times; (111)] were investigated. From a quantitative analysis of C 1s data, the distribution of CO on the various adsorption sites can be determined continuously during adsorption and desorption. These unique data show that the terrace sites are only occupied when the step sites are almost saturated, even at temperatures as low as 130 K. The coverage-dependent occupation of on-top and bridge adsorption sites on the (111) terraces of Pt(355) is found to differ from that on Pt(111), which is attributed to the finite width of the terraces and changes in adsorbate-adsorbate interactions. In particular, no long-range order of the adsorbate layer could be observed by low-energy electron diffraction. Further details are derived from sticking coefficient measurements using the method devised by King and Wells [Proc. R. Soc. London, Ser. A 339, 245 (1974)] and temperature-programmed desorption. The CO saturation coverage is found to be slightly smaller on the stepped surface as compared to that on Pt(111). The initial sticking coefficient has the same high value of 0.91 for both surfaces. &copy; 2006 American Institute of Physics.}, author = {Tränkenschuh, Barbara and Fritsche Richter, Nicole and Fuhrmann, Thomas and Papp, Christian and Zhu, Junfa and Denecke, Reinhard and Steinrück, Hans-Peter}, doi = {10.1063/1.2168441}, faupublication = {yes}, journal = {Journal of Chemical Physics}, peerreviewed = {Yes}, title = {{A} site-selective in situ study of {CO} adsorption and desorption on {Pt}(355)}, volume = {124}, year = {2006} } @article{faucris.120376784, abstract = {We consider the one-dimensional steady-state semiconductor device equations modelling a pnpn device. There are two relevant scalings of the equations corresponding to small and large applied voltages. In both scalings, the semiconductor equations can be considered as singularly perturbed. It turns out that the small-voltage scaling breaks down for current values between two saturation currents. In that interval, the large-voltage scaling has to be employed. For both scalings, we derive the first-order terms of an asymptotic expansion and show that the reduced problem has a solution. An example verifies that the current-voltage curves obtained have the expected qualitative structure. © 1989 Oxford University Press.}, author = {Steinrück, Hans-Peter}, doi = {10.1093/imamat/43.3.243}, journal = {IMA Journal of Applied Mathematics}, pages = {243-259}, peerreviewed = {Yes}, title = {{Asymptotic} analysis of the current-voltage curve of a pnpn semiconductor device}, volume = {43}, year = {1989} } @article{faucris.108311324, abstract = {We present a temperature-programmed x-ray photoelectron spectroscopy study of the thermal chemistry of acetylene, ethylene and propene on Ni(100) using synchrotron radiation. The use of a third generation light source makes it possible to measure high resolution photoemission spectra within a few seconds approaching the ideal of real-time analysis. The evolution of the C 1s core level spectra has been monitored in situ as a function of sample temperature from 90 to 530 K. Analysis of binding energies and changes in intensities and correlation with previous data from the literature have allowed us to distinguish the surface intermediates formed during the thermal reactions. The resultant temperature-dependent intensity curves clarify the dehydrogenation mechanisms of acetylene and ethylene and provide new insight into the decomposition of propene.}, author = {Whelan, Caroline and Neubauer, Ralf and Denecke, Reinhard and Steinrück, Hans-Peter}, doi = {10.1142/S0218625X02002968}, faupublication = {yes}, journal = {Surface Review and Letters}, pages = {789-795}, peerreviewed = {Yes}, title = {{A} temperature-programmed x-ray photoelectron spectroscopy study of the decomposition reactions of unsaturated hydrocarbons on {Ni}(100)}, volume = {9}, year = {2002} } @article{faucris.108461144, abstract = {An experimental test of the angular distribution function of particles originating from long capillaries has been performed. Gas pressures at the tube entrance corresponding to Knudsen numbers of 10-10 were used. The results can be described very well by the elementary Clausing theory. The cosine law for gas reflection inside the tubes is fulfilled with high accuracy. No differences in the behaviour of CO, CO, N and O could be detected. The investigation is also considered to be an accurate test of the simple beam detector used in the investigation. &copy; 1986.}, author = {Steinrück, Hans-Peter and Rendulic, K.D.}, faupublication = {no}, journal = {Vacuum}, pages = {213-215}, peerreviewed = {Yes}, title = {{A} test of capillary array beam sources for very large {Knudsen} numbers}, url = {https://www.scopus.com/record/display.uri?eid=2-s2.0-0022695136&origin=inward}, volume = {36}, year = {1986} } @article{faucris.241989493, abstract = {Ionic liquids (ILs) are used as ultrathin films in many applications. We studied the nanoscale arrangement within the first layer of 1,3-dimethylimidazolium bis[(trifluoromethyl)sulfonyl]imide ([C1C1Im] [Tf2N]) on Au(111) between 400 and 110 K in ultrahigh vacuum by scanning tunneling and noncontact atomic force microscopy with molecular resolution. Compared to earlier studies on similar ILs, a different behavior is observed, which we attribute to the small size and symmetrical shape of the cation: (a) In both AFM and STM only the anions are imaged; (b) only long-range-ordered but no amorphous phases are observed; (c) the hexagonal room-temperature phase melts 30-50 K above the IL's bulk melting point; (d) at 110 K, striped and hexagonal superstructures with two and three ion pairs per unit cell, respectively, are found. AFM turned out to be more stable at higher temperature, while STM revealed more details at low temperature.}, author = {Meusel, Manuel and Lexow, Matthias and Gezmis, Afra and Schötz, Simon and Wagner, Margareta and Bayer, Andreas and Maier, Florian and Steinrück, Hans-Peter}, doi = {10.1021/acsnano.0c03841}, faupublication = {yes}, journal = {ACS nano}, keywords = {atomic force microscopy (AFM); Au(111); interface; ionic liquids (ILs); scanning tunneling microscopy (STM)}, note = {CRIS-Team Scopus Importer:2020-08-28}, pages = {9000-9010}, peerreviewed = {Yes}, title = {{Atomic} {Force} and {Scanning} {Tunneling} {Microscopy} of {Ordered} {Ionic} {Liquid} {Wetting} {Layers} from 110 {K} up to {Room} {Temperature}}, volume = {14}, year = {2020} } @article{faucris.203643774, abstract = {Die moderne Atomphysik hat von der Bohrschen Theorie bis zu Schrödingers Wellentheorie einen Wandel sowohl in der mathematischen Behandlung als auch in der bildlichen Vorstellung durchgemacht. Am PC lassen sich heute viele abstrakte Rechenergebnisse dieser Theorien veranschaulichen. Dieses Ziel verfolgt das Programmpaket „atomos”︁, das auf unserer Homepage unter www.wiley‐vch.de/home/phiuz abrufbar is}, author = {Girwidz, Raimund and Gößwein, Oliver and Steinrück, Hans-Peter}, doi = {10.1002/1521-3943(200004)31:4<165::AID-PIUZ165>3.0.CO;2-0}, faupublication = {no}, journal = {Physik in unserer Zeit}, note = {UnivIS-Import:2018-09-04:Pub.2000.nat.dchph.lpc2.atomph}, pages = {165-167}, peerreviewed = {No}, title = {{Atomphysik} am {Computer}}, volume = {31}, year = {2000} } @book{faucris.110275704, author = {Girwidz, Raimund and Steinrück, Hans-Peter and Gößwein, Oliver}, doi = {10.1002/1521-3943(200004)31:4<165::AID-PIUZ165>3.0.CO;2-0}, faupublication = {no}, pages = {165-167}, publisher = {Wiley-VCH}, series = {Physik in unserer Zeit}, title = {{Atomphysik} am {Computer}}, volume = {31}, year = {2000} } @article{faucris.107805104, abstract = {The growth, structure formation and thermal disordering of (sub-)monolayer films of 1-butyl-1-methylpyrrolidinium-bis(trifluoromethylsulfonyl)imide [BMP][TFSA] grown under ultrahigh vacuum (UHV) conditions on Au(111) have been investigated using scanning tunneling microscopy (STM) and angle resolved X-ray photoelectron spectroscopy (ARXPS) under UHV conditions at temperatures between 100 and 298 K. At room temperature, two-dimensional film growth occurs up to one monolayer coverage, with both cations and anions in direct contact with the gold substrate, as shown by ARXPS, and STM images reveal a 2D liquid state of the adlayer. At lower temperatures, motion is frozen and a disordered 2D glass state as well as a 2D crystalline phase with long-range order are formed. The structure of the 2D crystalline phase is influenced by the underlying Au(111) reconstruction pattern. Annealing experiments reveal that the 2D crystalline phase is thermally more stable against melting than the 2D glass state, and that the stability is strongly affected by the adsorbate coverage. &copy; 2013 the Owner Societies.}, author = {Uhl, Benedikt and Cremer, Till and Roos, Michael and Maier, Florian and Steinrück, Hans-Peter and Behm, R.Jürgen}, doi = {10.1039/c3cp52184b}, faupublication = {yes}, journal = {Physical Chemistry Chemical Physics}, pages = {17295-17302}, peerreviewed = {Yes}, title = {{At} the ionic liquidmetal interface: {Structure} formation and temperature dependent behavior of an ionic liquid adlayer on {Au}(111)}, volume = {15}, year = {2013} } @article{faucris.314599692, abstract = {Molecular solar thermal systems (MOSTs) are molecular systems based on couples of photoisomers (photoswitches), which combine solar energy conversion, storage, and release. In this work, we address the catalytically triggered energy release in the promising MOST couple phenylethylesternorbornadiene/quadricyclane (PENBD/PEQC) on a Au(111) surface in a combined liquid-phase and surface science study. We investigated the system by photoelectrochemical infrared reflection absorption spectroscopy (PEC-IRRAS) in the liquid phase, conventional IRRAS and synchrotron radiation photoelectron spectroscopy (SRPES) in ultra-high vacuum (UHV). Au(111) is highly active towards catalytically triggered energy release. In the liquid phase, we did not observe any decomposition of the photoswitch, no deactivation of the catalyst within 100 conversion cycles and we could tune the energy release rate of the heterogeneously catalyzed process by applying an external potential. In UHV, submonolayers of PEQC on Au(111) are back-converted to PENBD instantaneously, even at 110 K. Multilayers of PEQC are stable up to ~220 K. Above this temperature, the intrinsic mobility of the film is high enough that PEQC molecules come into direct contact with the Au(111) surface, which catalyzes the back-conversion. We suggest that this process occurs via a singlet–triplet mechanism induced by electronic coupling between the PEQC molecules and the Au(111) surface.}, author = {Eschenbacher, Roman and Hemauer, Felix and Franz, Evanie and Leng, Andreas and Schwaab, Valentin and Waleska-Wellnhofer, Natalie and Freiberger, Eva Marie and Fromm, Lukas and Xu, Tao and Görling, Andreas and Hirsch, Andreas and Steinrück, Hans-Peter and Papp, Christian and Brummel, Olaf and Libuda, Jörg}, doi = {10.1002/cptc.202300155}, faupublication = {yes}, journal = {Chemphotochem}, keywords = {norbornadiene; photoswitches; quadricyclane; solar energy storage; surface chemistry}, note = {CRIS-Team Scopus Importer:2023-12-01}, peerreviewed = {Yes}, title = {{Au}-{Catalyzed} {Energy} {Release} in a {Molecular} {Solar} {Thermal} ({MOST}) {System}: {A} {Combined} {Liquid}-{Phase} and {Surface} {Science} {Study}}, volume = {8}, year = {2024} } @article{faucris.306930248, abstract = {Correction to: Scientific Reports, published online 17 March 2023 The original version of this Article contained an error in the spelling of the author Nicola Taccardi, which was incorrectly given as Nicola Tacardi. The original Article has been corrected.}, author = {Wittkämper, Haiko and Hock, Rainer and Weißer, Matthias and Dallmann, Johannes and Vogel, Carola and Raman, Narayanan and Taccardi, Nicola and Haumann, Marco and Wasserscheid, Peter and Hsieh, Tzung En and Maisel, Sven and Moritz, Michael and Wichmann, Christoph and Frisch, Johannes and Gorgoi, Mihaela and Wilks, Regan G. and Bär, Marcus and Wu, Mingjian and Spiecker, Erdmann and Görling, Andreas and Unruh, Tobias and Steinrück, Hans-Peter and Papp, Christian}, doi = {10.1038/s41598-023-35778-1}, faupublication = {yes}, journal = {Scientific Reports}, note = {CRIS-Team Scopus Importer:2023-06-30}, peerreviewed = {Yes}, title = {{Author} {Correction}: {Isolated} {Rh} atoms in dehydrogenation catalysis ({Scientific} {Reports}, (2023), 13, 1, (4458), 10.1038/s41598-023-31157-y)}, volume = {13}, year = {2023} } @article{faucris.121456764, abstract = {The adsorption of benzene on the Ni(110) surface was studied by TPD, LEED, NEXAFS and ARUPS. At initial coverages below &theta; = 0.10 ML (relative to Ni) benzene completely decomposes upon heating. At higher coverages molecular benzene desorption is also observed. At the saturation coverage of 0.23 &plusmn; 0.04 ML a sharp c(4 &times; 2) LEED pattern is observed with weak additional reflexes indicating a larger unit mesh. The ARUPS measurements for a dilute layer (&theta; ≃ 0.5&theta; ) suggest an orientation of the molecular plane parallel to the surface with C symmetry of the adsorption complex benzene/Ni(110) and the molecules azimuthally oriented with their corners along [001]. For the saturated layer the molecular plane is still parallel to the surface but the symmetry of the adsorption complex is lowered to C , due to an azimuthal rotation of the benzene molecules induced by strong lateral interactions in the densely packed saturated layer. The 2a{lg} band shows strong dispersion (0.8 eV) with the periodicity of the 2D bandstructure corresponding to a c(4 &times; 2) structure. For the coadsorption of benzene + CO a sharp c(4 &times; 4) LEED structure is observed with identical CO and benzene coverages of ~ 0.12 ML. The electronic structure, orientation and symmetry of benzene in the coadsorbed layer is identical to that in the dilute pure layer. The photon energy dependence of the photoionization cross section of the 2e{lu} level of benzene in the saturated layer shows a maximum at a photon energy of 25 eV, similar to benzene on Ni(111); the corresponding electron emission is centered along the surface normal. The NEXAFS spectra for the dilute and the saturated layer at normal incidence are also indicative of a flat-lying benzene molecule. &copy; 1991.}, author = {Huber, W. and Weinelt, M. and Zebisch, P. and Steinrück, Hans-Peter}, faupublication = {no}, journal = {Surface Science}, pages = {72-98}, peerreviewed = {Yes}, title = {{Azimuthal} reorientation of adsorbed molecules induced by lateral interactions: benzene/{Ni}(110)}, url = {https://www.scopus.com/record/display.uri?eid=2-s2.0-0026203654&origin=inward}, volume = {253}, year = {1991} } @article{faucris.123788984, author = {Brummel, Olaf and Besold, Daniel and Döpper, Tibor and Wu, Yanlin and Bochmann, Sebastian and Lazzari, Federica and Waidhas, Fabian and Bauer, Udo and Bachmann, Philipp and Papp, Christian and Steinrück, Hans-Peter and Görling, Andreas and Libuda, Jörg and Bachmann, Julien}, doi = {10.1002/cssc.201600765}, faupublication = {yes}, journal = {ChemSusChem}, keywords = {infrared spectroscopy; norbornadiene; quadricyclane; spectroelectrochemistry; voltammetry}, peerreviewed = {unknown}, title = {{Back} {Cover}: {Energy} {Storage} in {Strained} {Organic} {Molecules}: ({Spectro}){Electrochemical} {Characterization} of {Norbornadiene} and {Quadricyclane} ({ChemSusChem} 12/2016)}, volume = {9}, year = {2016} } @article{faucris.120347964, abstract = {Using photoelectron spectroscopy, we have investigated the band alignment at the interface of pseudomorphic BeTe/ZnSe(100) heterojunctions for different interface terminations. The heterostructures of high structural quality have been produced by molecular beam epitaxy; the interface termination was adjusted by variation of the growth parameters between the growth process of ZnSe and BeTe. The valence band offset for a Zn-rich BeTe/ZnSe interface is determined to be 1.26&plusmn;0.15 eV, for the Se-rich BeTe/ZnSe interface a value of 0.46&plusmn;0.15 eV is obtained. Our results show that the band alignment can be modified by the interface composition even for isovalent heterostructures. &copy; 1998 American Institute of Physics.}, author = {Nagelstraßer, M. and Dröge, H. and Fischer, F. and Litz, T. and Waag, Andreas and Landwehr, G. and Steinrück, Hans-Peter}, doi = {10.1063/1.367231}, faupublication = {no}, journal = {Journal of Applied Physics}, pages = {4253-4257}, peerreviewed = {Yes}, title = {{Band} discontinuities and local interface composition in {BeTe}/{ZnSe} heterostructures}, volume = {83}, year = {1998} } @article{faucris.120336304, abstract = {Different metallophthalocyanines and 2,4,6-triphenylpyrylium (TP ) ions were entrapped in different inorganic supports such as Y zeolite, mesoporous MCM-41, TiO-SiO and SiO following a specific protocol. The resulting supramolecular structures were characterized by chemical analysis and diffuse reflectance UV-Vis measurements. The determination of the band gap on the basis of UV-Vis measurements showed that the host is not a spectator in this process and an electronic interaction occurs that lowers the band gap of the support. The XPS measurements were performed with an in situ X-ray photoelectron spectrometer, which can be operated at pressures of up to 1 mbar at the sample. They indicated that the formation of the supramolecular structure generates a stable environment, in which the oxidation state of the metal can still be influenced by reaction of the metal center with gas molecules. The photocatalytic tests carried out in photodecomposition of dipropyl sulfide showed a good correlation between the band gap values and the photocatalytic activity for metallophthalocyanine complexes. It is remarkable that the triphenylpyrylium ion follows the same trend observed for metallophthalocyanines, although it is a different type of photosensitizer. &copy; the Owner Societies 2009.}, author = {Cojocaru, Bogdan and Neatu, Stefan and Parvulescu, Vasile I. and Dumbuya, Karifala and Steinrück, Hans-Peter and Gottfried, Michael and Aprile, Carmela and Garcia, Hermenegildo and Scaiano, J. C.}, doi = {10.1039/b902348h}, faupublication = {yes}, journal = {Physical Chemistry Chemical Physics}, pages = {5569-5577}, peerreviewed = {Yes}, title = {{Band} gap effect on the photocatalytic activity of supramolecular structures obtained by entrapping photosensitizers in different inorganic supports}, volume = {11}, year = {2009} } @article{faucris.108489744, abstract = {Using angle-resolved synchrotron-radiation photoemission spectroscopy we have determined the dispersion of the valence bands of BeTe(100) along &Gamma;X, i.e., the [100] direction. The measurements are analyzed with the aid of a first-principles calculation of the BeTe bulk band structure as well as of the photoemission peaks as given by the momentum-conserving bulk transitions. Taking the calculated unoccupied bands as final states of the photoemission process, we obtain an excellent agreement between experimental and calculated spectra and a clear interpretation of almost all measured bands. In contrast, the free-electron approximation for the final states fails to describe the BeTe bulk band structure along &Gamma;X properly.}, author = {Nagelstraßer, M. and Dröge, H. and Steinrück, Hans-Peter and Fischer, F. and Litz, T. and Waag, Andreas and Landwehr, G. and Fleszar, A. and Hanke, W.}, doi = {10.1103/PhysRevB.58.10394}, faupublication = {no}, journal = {Physical Review B}, pages = {10394-10400}, peerreviewed = {Yes}, title = {{Band} structure of {BeTe}: {A} combined experimental and theoretical study}, volume = {58}, year = {1998} } @article{faucris.108491064, abstract = {We report on the molecular beam epitaxy and the properties of Be-chalcogenides. Especially the interface between ZnSe and BeTe and BeTe/ZnSe superlattices have been studied by means of HRXRD (high resolution X-ray diffraction), HRTEM (high resolution transmission-electron-microscopy), RHEED (reflection-high-energy-electron-diffraction), photo-electron-spectroscopy (PES) and photo-luminescence (PL). A strong dependence of the structural and electronic properties of these superlattices (SL) on the interface configuration has been found. A high valence band offset of about 1 eV between BeTe and ZnSe has been determined by means of photo-luminescence and photo-electron-spectroscopy. &copy; 1998 Elsevier Science B.V.}, author = {Litz, T. and Fischer, F. and Lugauer, H.-J. and Keim, M. and Zehnder, U. and Ossau, W. and Gerhard, Th. and Gall, R. and Waag, Andreas and Landwehr, G. and Nagelstraßer, M. and Steinrück, Hans-Peter and Walter, Th. and Gerthsen, D.}, faupublication = {no}, journal = {Applied Surface Science}, pages = {429-434}, peerreviewed = {Yes}, title = {{Be}-chalcogenides: {Heteroepitaxy} and interface properties}, url = {https://www.scopus.com/record/display.uri?eid=2-s2.0-0031703255&origin=inward}, year = {1998} } @article{faucris.108491504, abstract = {The adsorption and desorption of benzene on a pseudomorphic Cu monolayer on Ni(111) has been investigated by temperature programmed desorption (TPD) and angle-resolved ultraviolet (UV) photoelectron spectroscopy (ARUPS) using linearly polarized synchrotron radiation. The experimental results are compared to those of an earlier investigation of benzene adsorbed on Ni(111). Benzene is weakly chemisorbed on the pseudomorphic Cu monolayer on Ni(111): Desorption of the first layer occurs in the temperature range between 155 and 230 K with no sign of dissociation; the analysis of the binding energies of the molecular benzene levels reveals small bonding shifts of 0.2-0.30 eV of the benzene &pi; levels as compared to 1.4 eV for the strongly chemisorbed saturated benzene layer on Ni(111). The orientation of benzene on Cu/Ni(111) is determined from the ARUPS spectra in combination with symmetry selection rules. For low coverages, the molecular plane is oriented parallel to the surface, as is also the case for benzene on Ni(111). However, no well defined azimuthal orientation is observed, which is attributed to frustrated rotations and/or the high mobility of the adsorbed molecules at the temperature of investigation (80 K). For the saturated first benzene layer on Cu/Ni(111), a tilting of the adsorbed molecules occurs due to lateral interactions.}, author = {Koschel, Herbert and Held, Georg and Trischberger, P. and Widdra, Wolf and Steinrück, Hans-Peter}, doi = {10.1016/S0039-6028(99)00707-4}, faupublication = {yes}, journal = {Surface Science}, pages = {125-136}, peerreviewed = {Yes}, title = {{Benzene} adsorption on a pseudomorphic {Cu} monolayer on {Ni}(111) - a combined {TPD} and {ARUPS} study}, volume = {437}, year = {1999} } @article{faucris.108461584, abstract = {Angle-resolved UPS spectra were taken of the coadsorbate systems ( 13 &times; 13)R13.9&deg; CO+ benzene and (3 &times; 3) NO+ benzene, on Ru(001). The component molecules were also studied as pure layers. From symmetry selection rules, the benzene molecule is shown to lie parallel to the surface and to retain six-fold symmetry for saturated benzene as well as for both coadsorbed layers. When coadsorbed with benzene, NO is present only in bridge sites. Comparing the pure and coadsorbed layers, the binding energies are different: the coadsorbed benzene orbitals shift to lower values and the CO and NO orbitals shift to higher values. These energy shifts are interpreted as a purely electrostatic initial-state change in the case of CO+ benzene. For NO+ benzene, it is suggested that this electrostatic effect is accompanied by some change in bonding. &copy; 1989.}, author = {Heimann, P.A. and Jakob, P. and Pache, T. and Steinrück, Hans-Peter and Menzel, Dietrich}, doi = {10.1016/0039-6028(89)90117-9}, faupublication = {no}, journal = {Surface Science}, pages = {282-300}, peerreviewed = {Yes}, title = {{Benzene} coadsorbed with {CO} and {NO} on {Ru}(001). {I}. {A} {UPS} study with synchrotron radiation}, volume = {210}, year = {1989} } @article{faucris.266769104, abstract = {Hydroxamic acids are an interesting anchor group for organic molecules on oxide surfaces, but very few studies exist on their adsorption on well-defined single-crystal surfaces under well-defined conditions. In the present paper, we use X-ray photoelectron spectroscopy to follow the adsorption of benzohydroxamic acid on a rutile TiO<inf>2</inf>(110)-(1×1) single-crystal surface. We compare evaporation in ultrahigh vacuum with deposition from ethanol and acetonitrile solutions. Furthermore, we carried out density functional theory calculations to support the assignment of adsorbates. Several species appear on the surface, which are most evident in the N 1s region. The low-coverage species can be explained as originating from a hydroxamate, and decomposed species related to oxygen vacancies or defects. Identification of the high-coverage species, however, remains elusive, and several possibilities are discussed.}, author = {Köbl, Julia and Fernández, Cynthia C. and Augustin, Lisa-Marie and Kataev, Elmar and Franchi, Stefano and Tsud, Nataliya and Pistonesi, Carolina and Pronsato, M. Estela and Jux, Norbert and Lytken, Ole and Williams, Federico J. and Steinrück, Hans-Peter}, doi = {10.1016/j.susc.2021.121955}, faupublication = {yes}, journal = {Surface Science}, keywords = {Benzohydroxamic acid; Density functional theory calculations; TiO; X-ray photoelectron spectroscopy (XPS)}, note = {CRIS-Team Scopus Importer:2021-12-03}, peerreviewed = {Yes}, title = {{Benzohydroxamic} acid on rutile {TiO2}(110)-(1×1)– a comparison of ultrahigh-vacuum evaporation with deposition from solution}, volume = {716}, year = {2022} } @article{faucris.210452078, abstract = {Alloy catalysts have, in many cases, superior properties compared to their single metal counterparts. To gain deeper insights, we used graphene-supported bimetallic nanocluster arrays as a model system. We investigated the site occupation and the dynamic behavior of the metal distribution during adsorption and thermal treatment of CO layers on PdPt alloy nanocluster arrays supported on the graphene/Rh(111) Moire. We find that the adsorption of CO combined with heating to 550 K leads to a rearrangement of the surface atoms, resulting in all the edge sites of the nanoclusters being occupied by Pd atoms. At the same time, Pt gets enriched at the surface.}, author = {Düll, Fabian and Bauer, Udo and Späth, Florian and Bachmann, Philipp and Steinhauer, Johann and Steinrück, Hans-Peter and Papp, Christian}, doi = {10.1039/c8cp03749c}, faupublication = {yes}, journal = {Physical Chemistry Chemical Physics}, pages = {21294-21301}, peerreviewed = {Yes}, title = {{Bimetallic} {Pd}-{Pt} alloy nanocluster arrays on graphene/{Rh}(111): formation, stability, and dynamics}, volume = {20}, year = {2018} } @article{faucris.280976600, abstract = {Adding to the versatile class of ionic liquids, we report a new series of hydrophilic polyethylene glycol-functionalized room-temperature ionic liquids, offering interesting thermo- and electrochemical behavior as well as remarkable surface properties. A scalable and generally applicable synthetic procedure for the preparation of N,N’-bis(polyethylene glycol)imidazolium salts, generally abbreviated as [(mPEGn)2Im][A] (n = 2‒6, A = I‒, OMs‒, PF6‒, NTf2‒) was developed. These ionic liquids were studied concerning their thermo- and electrochemical properties, such as phase transition behavior, decomposition temperature, viscosity, and density, as well as electrical conductivity and electrochemical stability, using i.a. differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), electrochemical impedance spectroscopy (EIS) and linear sweep voltammetry (LSV). Additionally, the surface properties were investigated by angle-resolved X-ray photoelectron spectroscopy (ARXPS) and the pendant drop method. olecular dynamics simulations complement the studies and provide insight into the molecular structure of the ionic liquids and their specific orientation at the liquid-vacuum interface.<br}, author = {Seidl, Vera and Bosch, Michael and Paap, Ulrike and Livraghi, Mattia and Zhai, Ziwen and Wick, Christian and Koller, Thomas Manfred and Wasserscheid, Peter and Maier, Florian and Smith, Ana-Suncana and Bachmann, Julien and Steinrück, Hans-Peter and Meyer, Karsten}, doi = {10.1016/j.jil.2022.100041}, faupublication = {yes}, journal = {Journal of Ionic Liquids}, pages = {100041}, peerreviewed = {Yes}, title = {{Bis}-polyethylene glycol-functionalized imidazolium ionic liquids: {A} multi-method approach towards bulk and surface properties}, volume = {2}, year = {2022} } @article{faucris.123154724, abstract = {Supported ionic liquid phase (SILP) catalysts are comprised of a thin ionic liquid film containing a homogeneous transition metal complex that is supported on a highly porous substrate. The application of functionalized activated carbon as a support material for SILP catalysts in a continuous gas-phase propene hydroformylation reaction reveals that the surface properties of the carbon support have a significant influence on the catalytic performance. The catalytic activity of the pristine activated carbon-based SILP catalysts was found to be negligibly small (TOF4h = 3.5 h(-1)) in contrast to that of common oxidic supports such as silica (TOF4h = 15 h(-1)) or alumina. By amine functionalization of the carbon support surface, a dramatic increase in catalytic activity could be observed outperforming the tested oxidic supports by an order of magnitude. A distinct relationship between increased nitrogen content and the point of zero charge of the support and the catalytic activity could be observed. The largest activity increase (TOF4h = 105 h(-1)) was found for functionalized activated carbon SILP catalysts featuring a high point of zero charge and a high nitrogen content. Despite the fact that aldol formation is catalyzed by a base, the respective alcohol was the only detectable byproduct in the reactions.}, author = {Weiß, Alexander and Munoz, Macarena and Haas, Alexander and Rietzler, Florian and Steinrück, Hans-Peter and Haumann, Marco and Wasserscheid, Peter and Etzold, Bastian}, doi = {10.1021/acscatal.5b02747}, faupublication = {yes}, journal = {ACS Catalysis}, keywords = {hydroformylation;supported ionic liquid phase;surface functionalization;amino groups;activated carbon}, pages = {2280-2286}, peerreviewed = {unknown}, title = {{Boosting} the {Activity} in {Supported} {Ionic} {Liquid}-{Phase}-{Catalyzed} {Hydroformylation} via {Surface} {Functionalization} of the {Carbon} {Support}}, volume = {6}, year = {2016} } @article{faucris.318013881, abstract = {The adsorption, reaction and thermal stability of bromine on Rh(111)-supported hexagonal boron nitride (h-BN) and graphene were investigated. Synchrotron radiation-based high-resolution x-ray photoelectron spectroscopy (XPS) and temperature-programmed XPS allowed us to follow the adsorption process and the thermal evolution in situ on the molecular scale. On h-BN/Rh(111), bromine adsorbs exclusively in the pores of the nanomesh while we observe no such selectivity for graphene/Rh(111). Upon heating, bromine undergoes an on-surface reaction on h-BN to form polybromides (170-240 K), which subsequently decompose to bromide (240-640 K). The high thermal stability of Br/h-BN/Rh(111) suggests strong/covalent bonding. Bromine on graphene/Rh(111), on the other hand, reveals no distinct reactivity except for intercalation of small amounts of bromine underneath the 2D layer at high temperatures. In both cases, adsorption is reversible upon heating. Our experiments are supported by a comprehensive theoretical study. DFT calculations were used to describe the nature of the h-BN nanomesh and the graphene moiré in detail and to study the adsorption energetics and substrate interaction of bromine. In addition, the adsorption of bromine on h-BN/Rh(111) was simulated by molecular dynamics using a machine-learning force field.}, author = {Freiberger, Eva Marie and Steffen, Julien and Waleska-Wellnhofer, Natalie and Hemauer, Felix and Schwaab, Valentin and Görling, Andreas and Steinrück, Hans-Peter and Papp, Christian}, doi = {10.1088/1361-6528/ad1201}, faupublication = {yes}, journal = {Nanotechnology}, keywords = {bromine; functionalization; graphene; hexagonal boron nitride; machine-learning force field; molecular dynamics; x-ray photoelectron spectroscopy}, note = {CRIS-Team Scopus Importer:2024-02-09}, peerreviewed = {Yes}, title = {{Bromination} of {2D} materials}, volume = {35}, year = {2024} } @article{faucris.311100127, abstract = {This study addresses a fundamental question in surface science: the adsorption of halogens on metal surfaces. Using synchrotron radiation-based high-resolution X-ray photoelectron spectroscopy (XPS), temperature-programmed XPS, low-energy electron diffraction (LEED) and density functional theory (DFT) calculations, we investigated the adsorption and thermal stability of bromine on Rh(111) in detail. The adsorption of elemental bromine on Rh(111) at 170 K was followed in situ by XPS in the Br 3d region, revealing two individual, coverage-dependent species, which we assign to fcc hollow- and bridge-bound atomic bromine. In addition, we find a significant shift in binding energy upon increasing coverage due to adsorbate-adsorbate interactions. Subsequent heating shows a high thermal stability of bromine on Rh(111) up to above 1000 K, indicating strong covalent bonding. To complement the XPS data, LEED was used to study the long-range order of bromine on Rh(111): we observe a (√3×√3)R30° structure for low coverages (≤0.33 ML) and a star-shaped compression structure for higher coverages (0.33–0.43 ML). Combining LEED and DFT calculations, we were able to visualize bromine adsorption on Rh(111) in real space for varying coverages.}, author = {Freiberger, Eva Marie and Steffen, Julien and Waleska-Wellnhofer, Natalie and Harrer, Aileen and Hemauer, Felix and Schwaab, Valentin and Görling, Andreas and Steinrück, Hans-Peter and Papp, Christian}, doi = {10.1002/cphc.202300510}, faupublication = {yes}, journal = {ChemPhysChem}, keywords = {adsorption sites; halogens on metals; high-resolution X-ray photoelectron spectroscopy; LEED; synchrotron radiation}, note = {CRIS-Team Scopus Importer:2023-09-29}, peerreviewed = {Yes}, title = {{Bromine} {Adsorption} and {Thermal} {Stability} on {Rh}(111): {A} {Combined} {XPS}, {LEED} and {DFT} {Study}}, year = {2023} } @article{faucris.120312984, abstract = {The adsorption of Ca on poly[2-(2-ethylhexyloxy)-5-methoxy-1,4-phenylene cyanovinylene] (MEH-CN-PPV) at 130 and 300 K has been studied by adsorption microcalorimetry, X-ray photoelectron spectroscopy (XPS), and low-energy He ion-scattering spectroscopy (LEIS). The initial heat of adsorption of Ca on MEH-CN-PPV at 300 K is 436 kJ/mol. The heat of adsorption increases to 464 kJ/mol at &sim;0.05 ML. We ascribe this initial heat to Ca abstracting cyano groups from the polymer backbone to make Ca(CN) clusters, plus a less important contribution due to Ca abstracting alkoxy groups to make Ca alkoxides. This is supported by XPS which shows the formation of new peaks in the N 1s and C 1s regions consistent with Ca(CN). There is also XPS evidence for Ca reacting with some of the ether groups to make Ca alkoxides at low coverage. Above 0.05 ML Ca coverage, the heat of adsorption decreases nearly exponentially to the sublimation enthalpy of bulk Ca solid (178 kJ/mol) by 5 ML. The observed behavior is attributed to the increasing probability of forming Ca nanoparticles and eventually a continuous solid Ca film on top of the reacted polymer. LEIS, which shows only a slow increase of the signal related to solid Ca, supports this model. Incoming Ca atoms undergo a kinetic competition between diffusing into the polymer to react with subsurface cyano or ether groups and forming or adding to three-dimensional Ca clusters on the surface. For studies done at 130 K, similar behavior is observed, with the heat of adsorption starting lower and decreasing more quickly to the heat of sublimation, already by 1.2 ML Ca coverage. This behavior along with the quicker growth of Ca on the surface of the polymer is attributed to the slower diffusion of Ca adatoms to subsurface cyano and ether groups. The effective thickness of &quot;reacted&quot; polymer (i.e., polymer which has lost its -CN groups and some alkoxy groups) is estimated to be 5.6 nm at 300 K but only 1.0 nm at 130 K. &copy; 2013 American Chemical Society.}, author = {Sharp, J. C. and Bebensee, Fabian and Baricuatro, J. H. and Steinrück, Hans-Peter and Gottfried, J. Michael and Campbell, C. T.}, doi = {10.1021/jp407825f}, faupublication = {yes}, journal = {Journal of Physical Chemistry C}, pages = {23781-23789}, peerreviewed = {Yes}, title = {{Calcium} thin film growth on a cyano-substituted poly(p-phenylene vinylene): {Interface} structure and energetics}, volume = {117}, year = {2013} } @article{faucris.114132304, abstract = {The adsorption of Ca vapor on two polyfluorenes, poly(9,9-di-n-hexyl-2,7- fluorene) (PDHF) and poly(9,9-di-n-hexyl-2,7-fluorene vinylene) (PDHFV), has been studied by adsorption microcalorimetry, low-energy He ion scattering spectroscopy (LEIS), and ultraviolet and X-ray photoelectron spectroscopies (UPS and XPS) at surface temperatures between 130 and &sim;400 K. At 300 K, the initial heat of adsorption of Ca on PDHF is 250 kJ/mol and on PDHFV is 315 kJ/mol. We ascribe this initial heat to Ca reacting with impurities or defects in the polymers. The heat of adsorption for both polymers decreases nearly exponentially to the sublimation enthalpy of bulk Ca solid (178 kJ/mol) by 0.75 ML. The observed behavior is attributed to the increasing probability of Ca finding and adding to solid three-dimensional Ca islands which nucleate and grow on the polymer surface and eventually grow into a continuous solid Ca film on top of the polymer. LEIS, which shows only a slow increase of the signals related to solid Ca, supports this model. Incoming Ca atoms are subject to a kinetic competition between diffusing into the polymer to react with subsurface defects or impurities versus adding to the three-dimensional Ca clusters on the surface. For studies done at 140 K, a similar behavior is observed, with the heat of adsorption starting lower and decreasing more quickly to the heat of sublimation, already by 0.1 ML Ca coverage. This behavior, along with the quicker growth of Ca on the surface of the polymer, is attributed to the slower diffusion of Ca adatoms to subsurface defects/impurities at 140 K than at 300 K. The opposite effect is observed when studied at 400 K. Calcium induces a downward band bending and work function decrease on both polymers, consistent with transfer of electrons from Ca to the polymers. &copy; 2014 American Chemical Society.}, author = {Sharp, J. C. and Feng, X. F. and Farrner, J. A. and Guo, Y. X. and Bebensee, Fabian and Baricuatro, J. H. and Zillner, Elisabeth and Zhu, J. F. and Steinrück, Hans-Peter and Gottfried, Michael and Campbell, C. T.}, doi = {10.1021/jp4105954}, faupublication = {yes}, journal = {Journal of Physical Chemistry C}, pages = {2953-2962}, peerreviewed = {Yes}, title = {{Calcium} thin film growth on polyfluorenes: {Interface} structure and energetics}, volume = {118}, year = {2014} } @article{faucris.113096104, abstract = {Carbon dioxide (CO2) absorption by the amine-functionalized ionic liquid (IL) dihydroxyethyl dimethylammonium taurinate at 310 K was studied using surface- and bulk-sensitive experimental techniques. From near-ambient pressure X-ray photoelectron spectroscopy at 0.9 mbar CO2, the amount of captured CO2 per mole of IL in the near-surface region is quantified to similar to 0.58 mol, with similar to 0.15 mol in form of carbamate dianions and similar to 0.43 mol in form of carbamic acid. From isothermal uptake experiments combined with infrared spectroscopy, CO2 is found to be bound in the bulk as carbamate (with nominally 0.5 mol of CO2 bound per 1 mol of IL) up to similar to 2.5 bar CO2, and as carbamic acid (with nominally 1 mol CO2 bound per 1 mol IL) at higher pressures. We attribute the fact that at low pressures carbamic acid is the dominating species in the near-surface region, while only carbamate is formed in the bulk, to differences in solvation in the outermost IL layers as compared to the bulk situation.}, author = {Niedermaier, Inga and Bahlmann, Matthias and Papp, Christian and Kolbeck, Claudia and Wei, Wei and Krick Calderon, Sandra and Grabau, Mathias and Schulz, Peter and Wasserscheid, Peter and Steinrück, Hans-Peter and Maier, Florian}, doi = {10.1021/ja410745a}, faupublication = {yes}, journal = {Journal of the American Chemical Society}, month = {Jan}, pages = {436-441}, peerreviewed = {Yes}, title = {{Carbon} {Dioxide} {Capture} by an {Amine} {Functionalized} {Ionic} {Liquid}: {Fundamental} {Differences} of {Surface} and {Bulk} {Behavior}}, volume = {136}, year = {2014} } @article{faucris.122798984, abstract = {We have investigated the surface chemistry of the polycyclic valence-isomer pair norbornadiene (NBD) and quadricyclane (QC) on Pt(111). The NBD/QC system is considered to be a prototype for energy storage in strained organic compounds. By using a multimethod approach, including UV photoelectron, high-resolution X-ray photoelectron, and IR reflection-absorption spectroscopic analysis and DFT calculations, we could unambiguously identify and differentiate between the two molecules in the multilayer phase, which implies that the energy-loaded QC molecule is stable in this state. Upon adsorption in the (sub)monolayer regime, the different spectroscopies yielded identical spectra for NBD and QC at 125 and 160K, when multilayer desorption takes place. This behavior is explained by a rapid cycloreversion of QC to NBD upon contact with the Pt surface. The NBD adsorbs in a η:η geometry with an agostic Pt-H interaction of the bridgehead CH subunit and the surface. Strong spectral changes are observed between 190 and 220K because the hydrogen atom that forms the agostic bond is broke. This reaction yields a norbornadienyl intermediate species that is stable up to approximately 380K. At higher temperatures, the molecule dehydrogenates and decomposes into smaller carbonaceous fragment}, author = {Bauer, Udo and Mohr, Susanne and Döpper, Tibor and Bachmann, Philipp and Späth, Florian and Düll, Fabian and Schwarz, Matthias and Brummel, Olaf and Fromm, Lukas and Pinkert, Ute and Görling, Andreas and Hirsch, Andreas and Bachmann, Julien and Steinrück, Hans-Peter and Libuda, Jörg and Papp, Christian}, doi = {10.1002/chem.201604443}, faupublication = {yes}, journal = {Chemistry - A European Journal}, keywords = {Catalysis; DFT calculations; IR spectroscopy; Photoelectron spectroscopy; Surfaces and interfaces}, month = {Jan}, pages = {1613-1622}, peerreviewed = {unknown}, title = {{Catalytically} {Triggered} {Energy} {Release} from {Strained} {Organic} {Molecules}: {The} {Surface} {Chemistry} of {Quadricyclane} and {Norbornadiene} on {Pt}(111)}, volume = {23}, year = {2017} } @article{faucris.211476718, abstract = {In the context of applications with thin ionic liquid (IL) films on solid supports, we studied the ion distribution within mixed thin IL films by angle-resolved X-ray photoelectron spectroscopy. After the deposition of 1-methyl-3-octylimidazolium hexafluorophosphate, [C(8)C(1)Im][PF6], on top of a wetting layer (WL) of 3-methyl-1-(3,3,4,4,4-pentafluorobutyl)imidazolium hexafluorophosphate, [PFBMIm][PF6], on Ag(111) at room temperature (RT), we find a preferential enrichment of the [PFBMIm](+) cation at the IL/vacuum interface. In a similar deposition experiment at 82 K, this cation exchange at the IL/solid interface does not occur. Upon heating the film from 82 K to RT, we observe the replacement of [C(8)C(1)Im](+) by [PFBMIrn]+ at the IL/vacuum interface between similar to 160 and similar to 220 K. No further changes in the surface composition were observed between 220 K and RT. Upon further heating the mixed IL film, we find the complete desorption of [PFBMIm] [PF6] from the mixed film below 410 K, leaving a WL of pure [C(8)C(1)Im][PF6] on Ag(111), which desorbs until 455 K.}, author = {Lexow, Matthias and Heller, Bettina and Partl, Gabriel and Bhuin, Radha Gobinda and Maier, Florian and Steinrück, Hans-Peter}, doi = {10.1021/acs.langmuir.8b0351}, faupublication = {yes}, journal = {Langmuir}, month = {Jan}, note = {CRIS-Team WoS Importer:2019-02-21}, pages = {398-405}, peerreviewed = {Yes}, title = {{Cation} {Exchange} at the {Interfaces} of {Ultrathin} {Films} of {Fluorous} {Ionic} {Liquids} on {Ag}(111)}, volume = {35}, year = {2019} } @article{faucris.120346864, abstract = {The adsorption and desorption behavior of cyclohexane and benzene on a clean, a potassium precovered, and an oxygen precovered Ni(111) surface have been studied by TPD and LEED. Below 120 K, cyclohexane is molecularly adsorbed on all substrates. On the bare Ni(111) surface cyclohexane shows Stranski-Krastanov growth as concluded from the subsequent development of 3 peaks &alpha;,&beta; and &gamma; in the TPD spectra that are assigned to desorption from the first layer, the second layer and bulk cyclohexane, respectively. From the zeroth order behavior of the a-peak, desorption from two-dimensional islands via a two-dimensional gas is concluded. Growth in two-dimensional islands is also suggested by the observation of a (&radic;7 &times; &radic;7)R19.1 LEED structure starting at a coverage as low as 0.04 ML up to the saturation coverage of 0.143 ML. On the potassium precovered surface (&theta; = 0.34 ML) cyclohexane exhibits Volmer-Weber growth as indicated by the observation of one single peak in the TPD spectra. This change in growth mode is attributed to a strongly reduced van der Waals interaction of cyclohexane to the K-precovered surface. The results are compared to those obtained for a Ni(111) surface precovered with a p(2 &times; 2) layer of oxygen (&theta; = 0.25 ML). Dramatic changes are also induced in the adsorption behavior of benzene by preadsorbed potassium. Benzene is no longer chemisorbed as on the clean Ni(111) surface, but is only weakly bonded to the substrate. Whereas layer-by-layer desorption is observed in the TPD spectra on the clean Ni(111) surface, on the K-precovered surface desorption of benzene occurs in one single peak, again indicating a change from Stranski-Krastanov growth on the clean surface to Volmer-Weber growth on the K-precovered surface. &copy; 1991.}, author = {Zebisch, P. and Huber, W. and Steinrück, Hans-Peter}, faupublication = {no}, journal = {Surface Science}, pages = {185-196}, peerreviewed = {Yes}, title = {{Changes} in the adsorption and desorption behavior of cyclohexane and benzene on {Ni}(111) induced by a monoatomic potassium layer}, url = {https://www.scopus.com/record/display.uri?eid=2-s2.0-0026412864&origin=inward}, volume = {244}, year = {1991} } @book{faucris.120373924, author = {Zhu, Junfa and Kinne, Martin and Fuhrmann, Thomas and Tränkenschuh, Barbara and Denecke, Reinhard and Steinrück, Hans-Peter}, editor = {Charles P. Norris}, faupublication = {yes}, pages = {217-235}, publisher = {Nova Science Publishers}, series = {Surface Science: New Research}, title = {{Chapter} 6. {Coadsorption} of {NO} and {Co} {Pt}(111) {Surface} {Studied} by {High}-{Resolution} {Synchrotron} {Radiation} {Photoemission}}, url = {https://www.novapublishers.com/catalog/product{\_}info.php?products{\_}id=3541}, year = {2005} } @article{faucris.120348184, abstract = {Ultra-thin copper films on Ni(111) (&Theta; &le; 1 ML) were studied by the adsorption of CO followed by high resolution X-ray photoelectron spectroscopy. Saturating the surface at 100 K with CO leads to adsorption on the entire surface, i.e. Cu-covered as well as bare Ni(111) areas. Upon annealing to 220 K the Cu-bonded CO molecules desorb leaving only the Ni-areas covered with CO. High resolution XPS spectra in the O 1s and Cu 2p regime have been recorded after adsorption at 100 K and after annealing to 220 K. The total area of Ni-terminated surface regions can be determined from the integrated O 1s XPS intensities after annealing; from the linear decrease of this area versus the amount of adsorbed copper a two-dimensional growth mode can be identified for layers which are annealed to 800 K. In addition, the CO adsorption sites on the Cu-terminated as well as on the Ni-terminated parts of the surface can be determined from the corresponding O Is binding energies. The changes in the O 1s peak shapes with increasing Cu coverage lead to the conclusion that the adlayers have a very high island density. &copy; 1998 Elsevier Science B.V. All rights reserved.}, author = {Held, Georg and Sklarek, Werner and Mayan, M. and Steinrück, Hans-Peter}, doi = {10.1016/S0039-6028(97)01065-0}, faupublication = {no}, journal = {Surface Science}, pages = {322-326}, peerreviewed = {Yes}, title = {{Characterization} of thin copper films on {Ni}(111) by {CO} titration}, year = {1998} } @article{faucris.107808184, abstract = {The concept of employing photonic crystal fibers for chemical and (photo)-catalytical transformations is presented. These optofluidic microdevices represent a versatile platform where light and fluids can interact for spectroscopic or photoactivation purposes. The use of photonic crystal fibers in chemistry and sensing is reviewed and recent applications as catalytic microreactors are presented. Results on homogeneous catalysis and the immobilization of homogeneous and heterogeneous catalysts in the fiber channels are discussed. The examples demonstrate that combining catalysis and the excellent light guidance of photonic crystal fibers provides unique features for example, for photocatalytic activation and quantitative photospectroscopic reaction analysis. &copy; 2013 WILEY-VCH Verlag GmbH &amp; Co. KGaA, Weinheim.}, author = {Schmidt, Matthias and Cubillas, Ana Maria and Taccardi, Nicola and Euser, Tijmen and Cremer, Till and Maier, Florian and Steinrück, Hans-Peter and Russell, Philip St. John and Wasserscheid, Peter and Etzold, Bastian}, doi = {10.1002/cctc.201200676}, faupublication = {yes}, journal = {ChemCatChem}, pages = {641-650}, peerreviewed = {Yes}, title = {{Chemical} and ({Photo})-{Catalytical} {Transformations} in {Photonic} {Crystal} {Fibers}}, volume = {5}, year = {2013} } @article{faucris.108279424, abstract = {In this combined experimental and theoretical work we demonstrate at the example of tetraphenylporphyrins on Ag(111) how differences in individual adsorbate orbitals and their interaction with the substrate can be exploited to switch the appearance of the adsorbate in scanning tunneling microscopy (STM) experiments, such that electronically and chemically very similar large molecules become distinguishable in STM. In particular, an intermixed layer consisting of 2HTPP (TPP ) tetraphenylporphyrin), CoTPP, and FeTPP molecules on Ag(111) was investigated, and it is demonstrated that STM images acquired with different bias voltages constitute fingerprints of the different molecules within the intermixed layer. By means of density functional calculations the observed features could be explained in detail and traced back to a direct orbital interaction of the adsorbed molecule with the surface. The explicit consideration of the surface in the calculations therefore turned out to be decisive to achieve good agreement with experiment. &copy; 2009 American Chemical Society.}, author = {Buchner, Florian and Warnick, Karl-Georg and Wölfle, Thorsten and Görling, Andreas and Steinrück, Hans-Peter and Hieringer, Wolfgang and Marbach, Hubertus}, doi = {10.1021/jp904680c}, faupublication = {yes}, journal = {Journal of Physical Chemistry C}, pages = {16450-16457}, peerreviewed = {Yes}, title = {{Chemical} fingerprints of large organic molecules in scanning tunneling microscopy: {Imaging} adsorbate-substrate coupling of metalloporphyrins}, volume = {113}, year = {2009} } @article{faucris.108291744, abstract = {No abstract is available for this content:}, author = {Steinrück, Hans-Peter and Libuda, Jörg and King, David A.}, doi = {10.1039/b814437k}, faupublication = {yes}, journal = {Chemical Society Reviews}, pages = {2153-2154}, peerreviewed = {Yes}, title = {{Chemistry} at surfaces}, volume = {37}, year = {2008} } @article{faucris.108293504, abstract = {An efficient route to prepare ionic liquids with chloroalkylsulfonate anions is presented; the synthesis proceeds in a one-step ring-opening reaction of sultones with an organic chloride salt and provides a very attractive access to new anion functionalised ionic liquids. &copy; The Royal Society of Chemistry.}, author = {Paape, Natalia and Wei, Wei and Bösmann, Andreas and Kolbeck, Claudia and Maier, Florian and Steinrück, Hans-Peter and Wasserscheid, Peter and Schulz, Peter}, doi = {10.1039/b805444d}, faupublication = {yes}, journal = {Chemical Communications}, pages = {3867-3869}, peerreviewed = {Yes}, title = {{Chloroalkylsulfonate} ionic liquids by ring opening of sultones with organic chloride salts}, year = {2008} } @article{faucris.108256764, abstract = {Tungsten - tungsten carbide thin films are deposited by metal-organic (MO)CVD on silica-coated silicon wafers using [cis-(1,3-butadiene) W(CO) ] and [cis-(1,3-cyclohexadiene) W(CO) ], respectively, as tunable precursor complexes. The compounds are prepared through photochemical ligand exchange reactions from [W(CO) ] and fully characterized, including X-ray structure determination and detailed differential thermal analysis (DTA)/thermogravimetry (TG) investigations. Gas-phase diffusion coefficients and the vapor pressure of the compounds are calculated. The MOCVD experiments are performed in a vertical cold-wall reactor and the exhaust gas is analyzed by gas chromatography (GC). X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), atomic force microscopy (AFM), and scanning electron microscopy (SEM) measurements are utilized for film characterization. Consequences of the high oxophilicity of freshly formed tungsten surfaces, consecutive surface reactions of the complex ligands, film growth, and film properties are discussed. Inside the layers, tungsten carbide is identified as the main component. &copy; 2010 WILEY-VCH Verlag GmbH &amp; Co. KGaA, Weinheim.}, author = {Jipa, Ilona and Heinemann, Frank Wilhelm and Schneider, Andreas and Popovska, Nadejda and Siddiqi, M. Aslam and Siddiqui, Rehan A. and Atakan, B. and Marbach, Hubertus and Papp, Christian and Steinrück, Hans-Peter and Zenneck, Ulrich}, doi = {10.1002/cvde.201006852}, faupublication = {yes}, journal = {Chemical Vapor Deposition}, pages = {239-247}, peerreviewed = {Yes}, title = {[cis-(1,3-diene) {2W}({CO}) 2] complexes as {MOCVD} precursors for the deposition of thin tungsten - {Tungsten} carbide films}, volume = {16}, year = {2010} } @article{faucris.108257644, abstract = {Novel multifunctional ceria based materials may show an improved performance in catalytic processes involving CO activation and reforming of hydrocarbons. Towards a more detailed understanding of the underlying surface chemistry, we have investigated CO activation on single crystal based ceria and magnesia/ceria model catalysts. All model systems are prepared starting from well-ordered and fully stoichiometric CeO (111) films on a Cu(111) substrate. Samples with different structure, oxidation state and compositions are generated, including CeO /Cu(111) (reduced), MgO/CeO /Cu(111) (reduced), mixed MgO-CeO /Cu(111) (stoichiometric), and mixed MgO-CeO /Cu(111) (reduced). The morphology of the model surfaces is characterized by means of scanning tunneling microscopy (STM), whereas the electronic structure and reactivity is probed by X-ray photoelectron spectroscopy (XPS). The experimental approach allows us to compare the reactivity of samples containing different types of Ce , Ce , and Mg ions towards CO at a sample temperature of 300 K. Briefly, we detect the formation of two CO -derived species, namely carbonate (CO ) and carboxylate (CO ) groups, on the surfaces of all investigated samples after exposure to CO at 300 K. In parallel to formation of the carbonate species, slow partial reoxidation of reduced CeO /Cu(111) occurs at large doses of CO . The reoxidation of the reduced ceria is largely suppressed on MgO-containing samples. The tendency for reoxidation of Ce to Ce by CO decreases with increasing degree of intermixing between MgO and CeO . Additionally, we have studied the stability of the formed carbonate species as a function of annealing temperature. &copy; 2010 EDP Sciences, SIF, Springer-Verlag Berlin Heidelberg.}, author = {Lykhach, Yaroslava and Staudt, Thorsten and Streber, Regine and Lorenz, Michael Peter Andreas and Bayer, Andreas and Steinrück, Hans-Peter and Libuda, Jörg}, doi = {10.1140/epjb/e2010-00110-x}, faupublication = {yes}, journal = {European Physical Journal B}, pages = {89-100}, peerreviewed = {Yes}, title = {{CO2} activation on single crystal based ceria and magnesia/ceria model catalysts}, volume = {75}, year = {2010} } @article{faucris.108317924, abstract = {The adsorption of DO on Pt(111) and the coadsorption with CO have been revisited by quantitative and in situ high-resolution X-ray photoelectron spectroscopy (XPS). During DO adsorption at 110 K, O 1s spectra clearly show the known formation of a bilayer and multilayers. As indicated by a binding energy change of the multilayer peak in the XP spectra recorded during heating, a structural change in the DO multilayer at the onset of multilayer desorption (&sim;145 K) is observed. Coadsorption of CO and DO leads to occupation of bridge and on-top sites by CO, with the order in site occupation reversed as compared to the clean surface, as previously observed. In addition, a new CO species is clearly resolved in C 1s spectra, which may be identified with CO on hollow sites. Upon DO desorption, this new species disappears and the CO site occupation changes to the value observed on the clean Pt(111). Induced by CO coadsorption, partial replacement of DO from the surface into higher layers is observed, indicated by a reduced desorption temperature of water and an O 1s binding energy shift toward the value of the multilayer signal. Our results suggest an intermixed first layer of CO and DO molecules; DO on top of this layer also influences the CO site distribution. On a surface precovered with 0.5 monolayer (ML) of CO, DO molecules can only adsorb on top of the CO layer and no mixed layer is formed; hence, no site change is observed. The preadsorbed DO bilayer lowers the initial CO sticking coefficient by a factor of &sim;13 as compared to the clean surface; this reduction is larger than previously detected.}, author = {Kinne, Martin and Fuhrmann, Thomas and Zhu, Junfa and Tränkenschuh, Barbara and Denecke, Reinhard and Steinrück, Hans-Peter}, doi = {10.1021/la035913w}, faupublication = {yes}, journal = {Langmuir}, pages = {1819-1826}, peerreviewed = {Yes}, title = {{Coadsorption} of {D2O} and {CO} on {Pt}(111) studied by in situ high-resolution x-ray photoelectron spectroscopy}, volume = {20}, year = {2004} } @incollection{faucris.122702624, address = {Hauppauge, NY}, author = {Zhu, Junfa and Kinne, Martin and Fuhrmann, Thomas and Tränkenschuh, Barbara and Denecke, Reinhard and Steinrück, Hans-Peter}, booktitle = {Surface Science: New Research}, faupublication = {yes}, isbn = {978-1-59454-404-0}, note = {UnivIS-Import:2015-04-20:Pub.2005.nat.dchph.lpc2.coadso}, pages = {217-235}, peerreviewed = {Yes}, publisher = {Nova Science Publishers}, title = {{Coadsorption} of {NO} and {CO} on a {Pt} (111) surface studied by high-resolution synchrotron radiation photoemission}, year = {2005} } @article{faucris.331163880, abstract = {Pure zinc tetraphenylporphyrin (ZnTPP) adsorbs on rutile TiO<inf>2</inf>(110) as flat-lying molecules, mostly interacting with the surface through weak van-der-Waals interactions. Pure monocarboxyphenyl triphenylporphyrin (2HMCTPP) forms a covalent bond to the rutile TiO<inf>2</inf>(110) surface through the carboxylic acid group, yielding densely-packed layers of upright-standing molecules. If given the chance, 2HMCTPP could therefore be expected to displace the weaker-bonding ZnTPP molecules. However, if 2HMCTPP is deposited on top of a ZnTPP layer, a coadsorption structure instead forms, with the carboxylic-acid groups of the 2HCMTPP molecules bonding to titanium atoms of the surface exposed by gaps between the molecules in the flat-lying ZnTPP adsorption structure.}, author = {Muth, Maximilian and Wolfram, Alexander and Steinrück, Hans-Peter and Lytken, Ole}, doi = {10.1002/cphc.202400795}, faupublication = {yes}, journal = {ChemPhysChem}, keywords = {Coadsorption; Oxides; Porpyhrins; XPS}, note = {CRIS-Team Scopus Importer:2024-11-15}, peerreviewed = {Yes}, title = {{Coadsorption} of {ZnTPP} and {2HMCTPP} on {Rutile} {TiO2}(110)}, year = {2024} } @article{faucris.116831044, author = {Bai, Yun and Flechtner, Ken and Marbach, Hubertus and Buchner, Florian and Hieringer, Wolfgang and Görling, Andreas and Shubina, Tatyana and Clark, Timothy and Steinrück, Hans-Peter and Gottfried, Michael}, faupublication = {yes}, journal = {ACS National Meeting Book of Abstracts}, peerreviewed = {unknown}, title = {{COLL} 106-{Surface} chemistry with metalloporphyrins and metallophthalocyanines: {Formation}, structure, and reactivity}, volume = {236}, year = {2008} } @article{faucris.114132964, abstract = {The adsorption and reaction of 4,4-dibromo-para-terphenyl (DBTP) and 1,3,5-tris(4-bromophenyl)benzene (TBB) on Cu(111) surface were studied with X-ray photoelectron spectroscopy (XPS), ultraviolet photoelectron spectroscopy (UPS), and density functional theory (DFT) calculations. In addition, complementary scanning tunneling microscopy (STM) data are presented. At submonolayer coverage, scission of C-Br bonds occurs between 170 and 240 K. The estimated activation energy for this process is considerably lower than the C-Br bond energy, indicating that bond scission is assisted by Cu atoms of the substrate. The remaining molecular backbones undergo linkage by C-Cu-C bonds to form organometallic oligomers. Annealing of these oligomers leads to the formation of C-C bonded covalent two-dimensional networks. Above monolayer coverage, complete C-Br cleavage requires higher temperature, confirming the role of the Cu surface in the reaction. The results provide insight into the C-Br bond scission as the initial step of the surface-assisted Ullmann reaction. &copy; 2014 American Chemical Society.}, author = {Chen, Min and Xiao, Jie and Steinrück, Hans-Peter and Wang, Shiyong and Wang, Weihua and Lin, Nian and Hieringer, Wolfgang and Gottfried, J. Michael}, doi = {10.1021/jp4121468}, faupublication = {yes}, journal = {Journal of Physical Chemistry C}, pages = {6820-6830}, peerreviewed = {Yes}, title = {{Combined} photoemission and scanning tunneling microscopy study of the surface-assisted ullmann coupling reaction}, volume = {118}, year = {2014} } @article{faucris.114775584, abstract = {The preparations of single (monolayer) and bulk carbides on the Mo(110) and Mo(100) single crystals are followed in situ at 1200 K using synchrotron-based high-resolution x-ray photoelectron spectroscopy of the C 1s and core Mo 3d(5/2) levels. By comparing the experimental results to first principles calculations using density functional theory, we suggest real-space surface structures for the carbide-modified surfaces. For a monolayer carbide on Mo(110), carbon dimers adsorb in the long-bridge site, most likely at a coverage of 3/8 ML carbon atoms per Mo surface atom. For the bulk carbide, we find a coverage of similar to 0.5ML on the surface, and the calculations show that single carbon atoms are more stable than dimers on the surface. The monolayer carbide on Mo(100) exhibits a coverage of similar to 1ML and agrees with previous studies, while the bulk carbide preparation probably leads to a faceting of the surfac}, author = {Gleichweit, Christoph and Neiß, Christian and Maisel, Sven and Bauer, Udo and Späth, Florian and Höfert, Oliver and Vollnhals, Florian and Drost, Martin and Marbach, Hubertus and Görling, Andreas and Steinrück, Hans-Peter and Papp, Christian}, doi = {10.1103/PhysRevB.92.014114}, faupublication = {yes}, journal = {Physical Review B}, pages = {014114}, peerreviewed = {Yes}, title = {{Comparative} study of the carbide-modified surfaces {C}/{Mo}(110) and {C}/{Mo}(100) using high-resolution x-ray photoelectron spectroscopy}, volume = {92}, year = {2015} } @article{faucris.120348404, abstract = {Using angle-resolved UV photoemission spectroscopy (ARUPS) with linerly polarized synchrotron radiation, the authors have studied the electronic structure, 2D band structure and orientation, and the energy dependence of the photoionization cross-sections of the valence levels for various pure and coadsorbed layers of CO and NO on Ni(111). This report summarizes and compares the results of these investigations. It is shown that the position of the shape resonance in the valence spectra cannot be taken as a measure for the intermolecular bonding distance.}, author = {Schneider, C. and Steinrück, Hans-Peter and Pache, T. and Heimann, P.A. and Coulman, D. and Umbach, E. and Menzel, Dietrich}, faupublication = {no}, journal = {Vacuum}, pages = {730-731}, peerreviewed = {Yes}, title = {{Comparative} study of the electronic structure of {CO}, {CO} + {K}, {NO} and {NO} + {K} on {Ni} (111) by {ARUPS} using synchrotron radiation}, url = {https://www.scopus.com/record/display.uri?eid=2-s2.0-0025554435&origin=inward}, volume = {41}, year = {1990} } @article{faucris.108495244, abstract = {We report results of high-resolution electron energy-loss measurements in transmission of CdTe films. In contrast to simple metals and other semiconductors studied experimentally so far, our results show a number of loss structures of comparable strength occupying a rather narrow energy region around the classical plasmon energy. With increasing momentum transfer these structures show no or only weak dispersion and the relative spectral weight shifts from the energetically lowest to the highest feature. The measurements are analyzed using ab initio calculations of the CdTe loss function. &copy; 1999 The American Physical Society.}, author = {Dröge, H. and Fleszar, A. and Hanke, W. and Sing, M. and Knupfer, M. and Fink, J. and Goschenhofer, F. and Becker, C.R. and Kargerbauer, R. and Steinrück, Hans-Peter}, faupublication = {no}, journal = {Physical Review B}, pages = {5544-5550}, peerreviewed = {Yes}, title = {{Complex} loss function of {CdTe}}, url = {https://www.scopus.com/record/display.uri?eid=2-s2.0-16344366781&origin=inward}, volume = {59}, year = {1999} } @article{faucris.235241876, abstract = {The adsorption behavior and the mobility of 2H-Tetranaphthylporphyrin (2HTNP) on Cu(111) was investigated by scanning tunneling microscopy (STM) at room temperature (RT). The molecules adsorb, like the structurally related 2HTPP, in the "inverted" structure with the naphthyl plane restricted to an orientation parallel to the Cu surface. The orientation of the four naphthyl groups yields altogether 16 possible conformations. Due to the existence of rotamer pairs, 10 different appearances are expected on the surface, and all of them are identified by STM at RT. Most interestingly, the orientation of the naphthyl groups significantly influences the diffusion behavior of the molecules on Cu(111). We identify three different groups of conformers, which are either immobile, medium or fast diffusing at RT. The mobility seems to decrease with increasing size of the footprint of the conformers on the surface.}, author = {Kuliga, Jan and Massicot, Stephen and Adhikari, Rajan and Ruppel, Michael and Jux, Norbert and Steinrück, Hans-Peter and Marbach, Hubertus}, doi = {10.1002/cphc.201901135}, faupublication = {yes}, journal = {ChemPhysChem}, note = {CRIS-Team WoS Importer:2020-03-03}, peerreviewed = {Yes}, title = {{Conformation} {Controls} {Mobility}: {2H}-{Tetranaphthylporphyrins} on {Cu}(111)}, year = {2020} } @article{faucris.215786035, author = {Bauer, Udo and Fromm, Lukas and Weiß, Cornelius and Bachmann, Philipp and Späth, Florian and Düll, Fabian and Steinhauer, Johann and Hieringer, Wolfgang and Görling, Andreas and Hirsch, Andreas and Steinrück, Hans-Peter and Papp, Christian}, doi = {10.1021/acs.jpcc.8b03746}, faupublication = {yes}, journal = {Journal of Physical Chemistry C}, pages = {7654-7664}, peerreviewed = {Yes}, title = {{Controlled} {Catalytic} {Energy} {Release} of the {Norbornadiene}/{Quadricyclane} {Molecular} {Solar} {Thermal} {Energy} {Storage} {System} on {Ni}(111)}, volume = {123}, year = {2019} } @article{faucris.210452345, abstract = {The reaction rate of the self-metalation of free-base tetraphenylporphyrins (TPPs) on Cu(111) increases with the number of cyano groups (n=0, 1, 2, 4) attached at the para positions of the phenyl rings. The findings are based on isothermal scanning tunneling microscopy (STM) measurements. At room temperature, all investigated free-base TPP derivatives adsorb as individual molecules and are aligned with respect to densely packed Cu substrate rows. Annealing at 400K leads to the formation of linear dimers and/or multimers via CN-Cu-CN bonds, accompanied by self-metalation of the free-base porphyrins following a first-order rate equation. When comparing the non-cyano-functionalized and the tetracyano-functionalized molecules, we find a decrease of the reaction rate by a factor of more than 20, corresponding to an increase of the activation energy from 1.48 to 1.59eV. Density functional theory (DFT) calculations give insights into the influence of the peripheral electron-withdrawing cyano groups and explain the experimentally observed effects.}, author = {Lepper, Michael and Köbl, Julia and Zhang, Liang and Meusel, Manuel and Hölzel, Helen and Lungerich, Dominik and Jux, Norbert and De Siervo, Abner and Meyer, Bernd and Steinrück, Hans-Peter and Marbach, Hubertus}, doi = {10.1002/anie.201803601}, faupublication = {yes}, journal = {Angewandte Chemie International Edition}, keywords = {cyano functionalization;porphyrinoids;scanning tunneling microscopy;self-metalation;surface chemistry}, pages = {10074-10079}, peerreviewed = {Yes}, title = {{Controlling} the {Self}-{Metalation} {Rate} of {Tetraphenylporphyrins} on {Cu}(111) via {Cyano} {Functionalization}}, volume = {57}, year = {2018} } @article{faucris.121296824, abstract = {We investigated the coordination self-assembly and metalation reaction of Cu with 5,10,15,20-tetra(4-pyridyl)porphyrin (2HTPyP) on a Au(111) surface by means of scanning tunneling microscopy, X-ray photoelectron spectroscopy, and density functional theory calculations. 2HTPyP was found to interact with Cu through both the peripheral pyridyl groups and the porphyrin core. Pairs of pyridyl groups from neighboring molecules coordinate Cu(0) atoms, which leads to the formation of a supramolecular metal-organic coordination network. The network formation occurs at room temperature; annealing at 450 K enhances the process. The interaction of Cu with the porphyrin core is more complex. At room temperature, formation of an initial complex Cu(0)-2HTPyP is observed. Annealing at 450 K activates an intramolecular redox reaction, by which the coordinated Cu(0) is oxidized to Cu(II) and the complex Cu(II)TPyP is formed. The coordination network consists then of Cu(II) complexes linked by Cu(0) atoms; that is, it represents a mixed-valence two-dimensional coordination network consisting of an ordered array of Cu(II) and Cu(0) centers. Above 520 K, the network degrades and the Cu atoms in the linking positions diffuse into the substrate, while the Cu(II)TPyP complexes form a close-packed structure that is stabilized by weak intermolecular interactions. Density functional theory investigations show that the reaction with Cu(0) proceeds via formation of an initial complex between metal atom and porphyrin followed by formation of Cu(II) porphyrin within the course of the reaction. The activation barrier of the rate limiting step was found to be 24-37 kcal mol depending on the method used. In addition, linear coordination of a Cu atom by two CuTPyP molecules is favorable according to gas-phase calculations. &copy; 2012 American Chemical Society.}, author = {Li, Yang and Xiao, Jie and Shubina, Tatyana and Chen, Min and Shi, Ziliang and Schmid, Martin and Steinrück, Hans-Peter and Gottfried, J. Michael and Lin, Nian}, doi = {10.1021/ja300593w}, faupublication = {yes}, journal = {Journal of the American Chemical Society}, pages = {6401-6408}, peerreviewed = {Yes}, title = {{Coordination} and metalation bifunctionality of {Cu} with 5,10,15,20-tetra(4- pyridyl)porphyrin: {Toward} a mixed-valence two-dimensional coordination network}, volume = {134}, year = {2012} } @article{faucris.108294824, abstract = {The in situ metalation of monolayers and multilayers of 2H-tetraphenylporphyrin (2HTPP) with Fe atoms on Ag(111) was studied with scanning tunneling microscopy (STM) and X-ray photoelectron spectroscopy (XPS). This surface-confined coordination reaction results in the formation of adsorbed iron(II)-tetraphenylporphyrin (FeTPP). It is demonstrated that metalation of 2HTPP is achieved either by depositing iron atoms onto a monolayer of 2HTPP at room temperature or, alternatively, by depositing 2HTPP onto a Ag(111) surface with predeposited iron. The latter route requires elevated temperatures, indicating that this reaction includes at least one step with an activation barrier. In addition, it is demonstrated that vapor deposited Fe atoms also react with multilayers of the porphyrin at room temperature under the formation of FeTPP. &copy; 2008 American Chemical Society.}, author = {Buchner, Florian and Flechtner, Ken and Bai, Yun and Zillner, Elisabeth and Kellner, Ina and Steinrück, Hans-Peter and Marbach, Hubertus and Gottfried, Michael}, doi = {10.1021/jp8052955}, faupublication = {yes}, journal = {Journal of Physical Chemistry C}, pages = {15458-15465}, peerreviewed = {Yes}, title = {{Coordination} of iron atoms by tetraphenylporphyrin monolayers and multilayers on {Ag}(111) and formation of iron-tetraphenylporphyrin}, volume = {112}, year = {2008} } @article{faucris.109604704, abstract = {The reactive interface between phthalocyanine (2HPc) and a Cu(111) surface was investigated with X-ray photoelectron spectroscopy (XPS) and temperature-programmed desorption/reaction (TPD/TPR). 2HPc reacts with Cu(111) to form copper(II) phthalocyanine (CuPc). For 2HPc submonolayers, the reaction starts already below 240 K. Thin 2HPc multilayers (4 monolayers) are completely converted into CuPc at elevated temperatures (500 K). To understand how molecules can react even though they are initially not in contact with the Cu surface, TPD/TPR studies with a NiPc interlayer between Cu and 2HPc were performed. These studies reveal the operation of an exchange mechanism, by which CuPc or NiPc molecules from the first layer are replaced by 2HPc molecules from higher layers. Once a 2HPc molecule comes into contact with the Cu surface, the molecule can react with the surface, forming CuPc, which can then be replaced by another unreacted 2HPc molecule. These findings have important implications for metal-organic interfaces in organic electronic devices, in which the charge carrier injection at the electrodes depends on the electronic properties of the interface. &copy; 2014 American Chemical Society.}, author = {Chen, Min and Röckert, Michael and Xiao, Jie and Drescher, Hans-Joerg and Steinrück, Hans-Peter and Lytken, Ole and Gottfried, J. Michael}, doi = {10.1021/jp5019235}, faupublication = {yes}, journal = {Journal of Physical Chemistry C}, pages = {8501-8507}, peerreviewed = {unknown}, title = {{Coordination} reactions and layer exchange processes at a buried metal-organic interface}, volume = {118}, year = {2014} } @article{faucris.115457144, abstract = {The oxidation of CO on Pt(111) was investigated simultaneously by near ambient pressure X-ray photoelectron spectroscopy and online gas analysis. Different CO:O reaction mixtures at total pressures of up to 1 mbar were used in continuous flow mode to obtain an understanding of the surface chemistry. By temperature-programmed and by isothermal measurements, the onset temperature of the reaction was determined for the different reactant mixtures. Highest turnover frequencies were found for the stoichiometric mixture. At elevated temperatures, the reaction becomes diffusion-limited in both temperature-programmed and isothermal measurements. In the highly active regime, no adsorbates were detected on the surface; it is therefore concluded that the catalyst surface is in a metallic state, within the detection limits of the experiment, under the applied conditions. Minor bulk impurities such as silicon were observed to influence the reaction up to total inhibition by formation of non-platinum oxides.}, author = {Krick Calderon, Sandra and Grabau, Mathias and Ovari, L. and Kress, B. and Steinrück, Hans-Peter and Papp, Christian}, doi = {10.1063/1.4940318}, faupublication = {yes}, journal = {Journal of Chemical Physics}, peerreviewed = {Yes}, title = {{CO} oxidation on {Pt}(111) at near ambient pressures}, volume = {144}, year = {2016} } @article{faucris.122870044, author = {Menzel, Dietrich and Rocker, G. and Steinrück, Hans-Peter and Coulman, D. and Heimann, P.A. and Huber, W. and Zebisch, P. and Lloyd, D.R.}, doi = {10.1063/1.462127}, faupublication = {no}, journal = {Journal of Chemical Physics}, pages = {1724-1734}, peerreviewed = {Yes}, title = {{CORE} {EXCITATION}, {DECAY}, {AND} {FRAGMENTATION} {IN} {SOLID} {BENZENE} {AS} {STUDIED} {BY} {X}-{RAY} {ABSORPTION}, {RESONANT} {AUGER}, {AND} {PHOTON} {STIMULATED} {DESORPTION}}, volume = {96}, year = {1992} } @article{faucris.108322984, abstract = {The adsorption of CO and benzene on pseudomorphic Cu monolayers on Ni(111) and Ru(0001) shows pronounced differences: For Cu/Ni(111) a behavior very similar to that of Cu(111) is observed, for Cu/Ru(0001) the adsorbate substrate bond is significantly strengthened for both molecules, as is deduced from a shift of the desorption temperature to higher values. Based on angle resolved UV photoelectron spectroscopy using synchrotron radiation at BESSY and density functional calculations we have determined the two-dimensional band structure of the pseudomorphic Cu monolayers on Ni(111) and Ru(0001). Our results show that for Cu/Ni(111) only weak coupling of the Cu3d states to the Ni substrate states occurs. On the other hand, strong coupling is observed for Cu/Ru(0001). This difference is made responsible for the strongly modified chemical properties of Cu/Ru(0001) as compared to Cu/Ni(111). &copy; 2001 Elsevier Science B.V.}, author = {Koschel, Herbert and Birkenheuer, U. and Held, Georg and Steinrück, Hans-Peter}, doi = {10.1016/S0039-6028(01)00889-5}, faupublication = {yes}, journal = {Surface Science}, pages = {113-125}, peerreviewed = {Yes}, title = {{Correlation} between chemical properties and electronic structure of pseudomorphic {Cu} monolayers on {Ni}(1 1 1) and {Ru}(0 0 0 1)}, volume = {477}, year = {2001} } @article{faucris.267475898, abstract = {In the original version of this article, Fig. 6 was plotted incorrectly, since in the input file the data on the polar angle axis were inserted in the inverse order. The correct Fig. 6 is shown below (caption remains unchanged). The error also concerns the deduced angles of the molecular plane relative to the surface plane (polar tilt angle), which are addressed in the manuscript on page 5, left column. The text should correctly read: "Fitting yields a polar tilt angle of 25° of the phenyl ring plane with respect to the surface normal with an azimuthal angle of 42° for the monodentate monolayer (380 K), and a polar tilt angle of 26° with an azimuthal angle of 43° for the mixed bidentate (or mono- and tridentate) monolayer (650–780 K). The fitting procedure was performed following the procedure from Ref. [37] In line with the unchanged electronic structure, the molecular orientation does not change (within the margin of error) when a monodentate monolayer of phenylphosphonic acid is annealed to form a mixed bidentate layer. Notably, for the onefold deprotonated bidentate, a polar tilt angle of ∼40° is estimated from Fig. 8 in Ref. [9]. For comparison, we note that 0.85 ML of phenylphosphonic acid adsorbs on anatase TiO<inf>2</inf>(101) surfaces at room temperature with a phenyl ring tilted 25° with respect to the surface normal.” Furthermore, the denoted value for the polar angle in the abstract and the summary should be changed to 25° The corrected texts read: Abstract: “Furthermore, the phenyl ring is tilted ∼25º with respect to the surface normal and it either forms 45° or is randomly oriented with respect to [001] crystallographic direction.” Conclusion: “Both monolayers possess essentially the same electronic structure with molecules tilted ∼25° with respect to the surface normal and with either a random azimuthal orientation or a 45° one.”}, author = {Köbl, Julia and Wechsler, Daniel and Kataev, Elmar and Williams, Federico J. and Tsud, Nataliya and Franchi, Stefano and Steinrück, Hans-Peter and Lytken, Ole}, doi = {10.1016/j.susc.2021.122004}, faupublication = {yes}, journal = {Surface Science}, note = {CRIS-Team Scopus Importer:2021-12-24}, peerreviewed = {Yes}, title = {{CORRIGENDUM}: {Adsorption} of phenylphosphonic acid on rutile {TiO2}(110) ({Surface} {Science} (2020) 698, ({S0039602819309410}), (10.1016/j.susc.2020.121612))}, volume = {717}, year = {2022} } @article{faucris.202401867, abstract = {Adsorption of 5-monocarboxyphenyl-10,15,20-triphenylporphyrin (MCTPP) to rutile TiO2(110) at room temperature produces molecules on the surface covalently anchored through the carboxylate group, coadsorbed with hydroxyl groups. At elevated temperatures, the free-base porphyrin molecules metalate on the surface, forming what we expect to be titanyl (Ti=O) porphyrin. The reaction is strongly coverage dependent with lower coverages metalating at lower temperatures, possibly caused by flat-lying molecules at low coverages being in closer proximity to the surface. This is in contrast to the behavior when exposed to Zn2+ ions in solution, where the coverage dependency is much less pronounced.}, author = {Wechsler, Daniel and Fernandez, Cynthia C. and Steinrück, Hans-Peter and Lytken, Ole and Williams, Federico J.}, doi = {10.1021/acs.jpcc.7b12717}, faupublication = {yes}, journal = {Journal of Physical Chemistry C}, pages = {4480-4487}, peerreviewed = {Yes}, title = {{Covalent} {Anchoring} and {Interfacial} {Reactions} of {Adsorbed} {Porphyrins} on {Rutile} {TiO2}(110)}, volume = {122}, year = {2018} } @article{faucris.112660724, abstract = {Graphene, a truly two-dimensional and fully &pi;-conjugated honeycomb carbon network, is currently evolving into the most promising successor to silicon in micro- and nanoelectronic applications. However, its wider application is impeded by the difficulties in opening a bandgap in its gapless band-structure, as well as the lack of processability in the resultant intrinscially insoluble material. Covalent chemical modification of the &pi;-electron system is capable of addressing both of these issues through the introduction of variable chemical decoration. Although there has been significant research activity in the field of functionalized graphene, most work to date has focused on the use of graphene oxide. In this Article, we report on the first wet chemical bulk functionalization route beginning with pristine graphite that does not require initial oxidative damage of the graphene basal planes. Through effective reductive activation, covalent functionalization of the charged graphene is achieved by organic diazonium salts. Functionalization was observed spectroscopically, and successfully prevents reaggregation while providing solubility in common organic media. &copy; 2011 Macmillan Publishers Limited. All rights reserved.}, author = {Englert, Jan and Dotzer, Christoph and Yang, Guang and Schmid, Martin and Papp, Christian and Gottfried, Michael and Steinrück, Hans-Peter and Spiecker, Erdmann and Hauke, Frank and Hirsch, Andreas and Hauke, Frank and Spiecker, Erdmann}, doi = {10.1038/nchem.1010}, faupublication = {yes}, journal = {Nature Chemistry}, pages = {279-286}, peerreviewed = {Yes}, title = {{Covalent} bulk functionalization of graphene}, volume = {3}, year = {2011} } @article{faucris.107144224, abstract = {Using temperature-programmed desorption, supported by X-ray photoelectron spectroscopy and scanning tunneling microscopy, a comprehensive overview of the main reactions of 5,10,15,20-tetraphenyl-21H,23H-porphyrin (2HTPP) on Cu(111) as a function of coverage and temperature is obtained. Three reactions were identified: metalation with Cu substrate atoms, stepwise partial dehydrogenation, and finally complete dehydrogenation. At low coverage the reactions are independent of coverage, but at higher coverage metalation becomes faster and partial dehydrogenation slower. This behavior is explained by a weaker interaction between the iminic nitrogen atoms and the Cu(111) surface in the high-coverage checkerboard structure, leading to faster metalation, and the stabilizing effect of T-type interactions in the [Cu(TPP)] islands formed at high coverage after metalation, leading to slower dehydrogenation. Based on the amount of hydrogen released and the appearance in STM, a structure of the partially dehydrogenated molecule is suggested.}, author = {Röckert, Michael and Franke, Matthias and Tariq, Quratulain and Ditze, Stefanie and Stark, Michael Werner and Uffinger, Patrick and Wechsler, Daniel and Singh, Upendra and Xiao, Jie and Marbach, Hubertus and Steinrück, Hans-Peter and Lytken, Ole}, doi = {10.1002/chem.201402420}, faupublication = {yes}, journal = {Chemistry - A European Journal}, pages = {8948--8953}, peerreviewed = {Yes}, title = {{Coverage}- and {Temperature}-{Dependent} {Metalation} and {Dehydrogenation} of {Tetraphenylporphyrin} on {Cu}(111)}, volume = {20}, year = {2014} } @article{faucris.108326504, abstract = {With its five ordered phases of adsorbed benzene (three commensurate and two incommensurate) the Ru(0 0 0 1) surface offers the unique possibility to study the local adsorption geometry of this molecule on a metal surface over a wide coverage range. We have performed low energy electron diffraction I-V structure analyses of all three commensurate superstructures p(2&radic;3&times;2&radic;3)R30&deg; (&Theta; = 0.083 ML), c(2&radic;3&times;4)rect (&Theta; = 0.125 ML), and p(&radic;7&times;&radic;7)R19&deg; (&Theta; = 0.143 ML). Despite the different lateral distances and lattice symmetries, the geometry of the adsorption complex, i.e. the benzene molecule together with the three Ru atoms forming the hcp adsorption site underneath, is exactly the same in all three phases. We find a significant crown-like buckling distortion of the C ring of about 0.1 angstroms and a small expansion of less than 0.1 angstroms which is within the error bar of the structure determination. The vertical distance between the carbon atoms and the first layer Ru atoms is 2.11 angstroms. The average vertical distance d between the first and the second Ru layer decreases slightly from 2.09 to 2.07 angstroms (&plusmn;0.05 angstroms) with increasing coverage whereas d increases from 2.13 to 2.16 angstroms (&plusmn;0.07 angstroms). The largest influence of variations in the benzene coverage is seen for the Ru atoms which are not in direct contact with the benzene molecules.}, author = {Braun, Wolfgang and Held, Georg and Steinrück, Hans-Peter and Stellwag, C. and Menzel, Dietrich}, doi = {10.1016/S0039-6028(00)01042-6}, faupublication = {yes}, journal = {Surface Science}, pages = {18-36}, peerreviewed = {Yes}, title = {{Coverage}-dependent changes in the adsorption geometries of ordered benzene layers on {Ru}(0 0 0 1)}, volume = {475}, year = {2001} } @article{faucris.113099624, abstract = {In this study, we investigate the peculiar coverage dependent supramolecular arrangement of 2H-tetraphenylporhpyrin (2HTPP) on Cu(111) with scanning tunneling microscopy at room-temperature. At low coverage, &quot;slow&quot; diffusion of individual 2HTPP molecules along the close-packed atomic rows of the substrate is observed, and no supramolecular ordering occurs. However, at higher coverage, the formation of ordered, checkerboard-like domains is found, with two molecules per unit cell at different distances from the surface. This behavior is attributed to a complex interplay of site specific molecule-substrate interaction, mainly the strong interaction between the iminic N atoms and Cu substrate atoms, with intermolecular T-type and &pi;-&pi; interactions. &copy; 2013 American Chemical Society.}, author = {Stark, Michael Werner and Ditze, Stefanie and Drost, Martin and Buchner, Florian and Steinrück, Hans-Peter and Marbach, Hubertus}, doi = {10.1021/la3046753}, faupublication = {yes}, journal = {Langmuir}, pages = {4104-4110}, peerreviewed = {Yes}, title = {{Coverage} dependent disorder-order transition of {2H}-tetraphenylporphyrin on {Cu}(111)}, volume = {29}, year = {2013} } @article{faucris.236509551, abstract = {Metal adatoms play a key role in surface diffusion, adsorption conformation, and self-assembly of porphyrin molecules on metal surfaces. Herein, we study the specific influence of coadsorption of Fe, Co, and Pd atoms on the behavior of 2H-tetrakis(p-cyano)phenylporphyrin (2H-TCNPP) on Cu(111) using scanning tunneling microscopy. Upon co-deposition of Fe and Co, the molecules form one-dimensional (1D) linear chains after mild annealing on Cu(111) driven by the interaction of its cyano groups with metal adatoms. A similar behavior has been observed previously on Cu(111), mediated by Cu adatoms, where the functional CN groups were also found to lower the reaction rate of the so-called porphyrin self-metalation reaction with Cu atoms significantly, in comparison to the non-cyano-functionalized porphyrin. Upon co-deposition of Pd and mild annealing, we find a remarkably different behavior, that is, a massive reorganization from 1D molecular chains to a peculiar rectangular 2D (two-dimensional) network. The molecular appearance changes to a clover shape, which is attributed to a Pd-induced dehydrogenation and subsequent ring closure reaction of the phenyl and pyrrole groups.}, author = {Dos Santos, Alisson Ceccatto and De Campos Ferreira, Rodrigo Cezar and Moreno-Lopez, Juan Carlos and Barreto, Lucas and Lepper, Michael and Landers, Richard and Steinrück, Hans-Peter and Marbach, Hubertus and De Siervo, Abner}, doi = {10.1021/acs.chemmater.9b05256}, faupublication = {yes}, journal = {Chemistry of Materials}, note = {CRIS-Team Scopus Importer:2020-03-27}, pages = {2114-2122}, peerreviewed = {Yes}, title = {{Cyano}-{Functionalized} {Porphyrins} on {Cu}(111) from {One}-{Dimensional} {Wires} to {Two}-{Dimensional} {Molecular} {Frameworks}: {On} the {Role} of {Co}-{Deposited} {Metal} {Atoms}}, volume = {32}, year = {2020} } @incollection{faucris.118980884, address = {Berlin, Heidelberg, New York}, author = {Held, Georg and Steinrück, Hans-Peter}, booktitle = {Landolt-Börnstein "Physics of Covered Solid Surfaces - Adsorbed Layers on Surfaces"}, doi = {10.1007/b12050}, faupublication = {yes}, isbn = {978-3-540-20281-3}, note = {UnivIS-Import:2015-04-20:Pub.2005.nat.dchph.lpc2.cyclic}, pages = {300-369}, peerreviewed = {unknown}, publisher = {Springer}, title = {{Cyclic} hydrocarbons}, volume = {III/42}, year = {2005} } @article{faucris.107825124, abstract = {Radiography of a structure skeleton: Cyclic thiouronium ionic liquids have been synthesized and characterized in such a way that the straightforward introduction of three different alkyl substituents at the cation has been realized. X-ray induced photoelectron spectroscopy studies indicated a significant electronic contribution of the free electrons at the sulfur to stabilize the cationic charge, leading to structures with peculiar physicochemical properties (see figure). Copyright &copy; 2012 WILEY-VCH Verlag GmbH &amp; Co. KGaA, Weinheim.}, author = {Taccardi, Nicola and Niedermaier, Inga and Maier, Florian and Steinrück, Hans-Peter and Wasserscheid, Peter}, doi = {10.1002/chem.201200971}, faupublication = {yes}, journal = {Chemistry - A European Journal}, pages = {8288-8291}, peerreviewed = {Yes}, title = {{Cyclic} thiouronium ionic liquids: {Physicochemical} properties and their electronic structure probed by {X}-ray induced photoelectron spectroscopy}, volume = {18}, year = {2012} } @misc{faucris.110297924, author = {Steinrück, Hans-Peter}, faupublication = {no}, note = {UnivIS-Import:2015-03-05:Pub.1986.nat.dchph.lpc2.daspri}, peerreviewed = {automatic}, title = {{Das} {Prinzip} der {Detaillierten} {Gleichgewichte} im {System} {H2}/{Nickel} und {CO}/{Nickel}}, year = {1986} } @misc{faucris.120382284, author = {Steinrück, Hans-Peter}, faupublication = {no}, title = {{Das} {Prinzip} der {Detaillierten} {Gleichgewichte} im {System} {H} ₂/{Nickel} und {CO}/{Nickel}}, year = {1986} } @article{faucris.121297264, abstract = {The identification of defects and their controlled generation in titanate nanostructures is a key to their successful application in photoelectronic devices. We comprehensively explored the effect of vacuum annealing on morphology and composition of Na Ti O nanowires and protonated H Ti O nanoscrolls using a combination of scanning electron microscopy, Auger and Fourier-transform infrared (FT-IR) spectroscopy, as well as ab initio density functional theory (DFT) calculations. The observation that H Ti O nanoscrolls are more susceptible to electronic reduction and annealing-induced n-type doping than Na Ti O nanowires is attributed to the position of the conduction band minimum. It is close to the vacuum level and, thus, favors the Fermi level-induced compensation of donor states by cation vacancies. In agreement with theoretical predictions that suggest similar formation energies for oxygen and sodium vacancies, we experimentally observed the annealing induced depletion of sodium from the surface of the nanowires. &copy; 2012 American Chemical Society.}, author = {Vittadini, Andrea and Schirmer, Michael and Walz, Marie-Madeleine and Vollnhals, Florian and Lukasczyk, Thomas and Steinrück, Hans-Peter and Marbach, Hubertus and Riss, Alexander and Elser, Michael J. and Schürer, Benedikt and Diwald, Oliver}, doi = {10.1021/la301129v}, faupublication = {yes}, journal = {Langmuir}, pages = {7851-7858}, peerreviewed = {Yes}, title = {{Defects} in oxygen-depleted titanate nanostructures}, volume = {28}, year = {2012} } @article{faucris.107810164, abstract = {Dodecahydro-N-ethylcarbazole (H-NEC) has been proposed as a potential liquid organic hydrogen carrier (LOHC) for chemical energy storage, as it combines both favourable physicochemical and thermodynamic properties. The design of optimised dehydrogenation catalysts for LOHC technology requires a detailed understanding of the reaction pathways and the microkinetics. Here, we investigate the dehydrogenation mechanism of H-NEC on Pd(111) by using a surface-science approach under ultrahigh vacuum conditions. By combining infrared reflection-absorption spectroscopy, density functional theory calculations and X-ray photoelectron spectroscopy, surface intermediates and their stability are identified. We show that H-NEC adsorbs molecularly up to 173 K. Above this temperature (223 K), activation of C-H bonds is observed within the five-membered ring. Rapid dehydrogenation occurs to octahydro-N-ethylcarbazole (H-NEC), which is identified as a stable surface intermediate at 223 K. Above 273 K, further dehydrogenation of H -NEC proceeds within the six-membered rings. Starting from clean Pd(111), C-N bond scission, an undesired side reaction, is observed above 350 K. By complementing surface spectroscopy, we present a temperature-programmed molecular beam experiment, which permits direct observation of dehydrogenation products in the gas phase during continuous dosing of the LOHC. We identify H-NEC as the main product desorbing from Pd(111). The onset temperature for H-NEC desorption is 330 K, the maximum reaction rate is reached around 550 K. The fact that preferential desorption of H -NEC is observed even above the temperature threshold for H -NEC dehydrogenation on the clean surface is attributed to the presence of surface dehydrogenation and decomposition products during continuous reactant exposure. &copy; 2013 Wiley-VCH Verlag GmbH &amp; Co. KGaA, Weinheim.}, author = {Amende, Maximilian and Schernich, Stefan and Sobota, Marek and Nikiforidis, Ioannis and Hieringer, Wolfgang and Assenbaum, Daniel and Gleichweit, Christoph and Drescher, Hans-Jörg and Papp, Christian and Steinrück, Hans-Peter and Görling, Andreas and Wasserscheid, Peter and Laurin, Mathias and Libuda, Jörg}, doi = {10.1002/chem.201301323}, faupublication = {yes}, journal = {Chemistry - A European Journal}, pages = {10854-10865}, peerreviewed = {Yes}, title = {{Dehydrogenation} mechanism of liquid organic hydrogen carriers: {Dodecahydro}-{N}-ethylcarbazole on {Pd}(111)}, volume = {19}, year = {2013} } @article{faucris.121297484, abstract = {To elucidate the dehydrogenation mechanism of dodecahydro-N-ethylcarbazole (H-12-NEC) on supported Pd catalysts, we have performed a model study under ultra high vacuum (UHV) conditions. H-12-NEC and its final dehydrogenation product, N-ethylcarbazole (NEC), were deposited by physical vapor deposition (PVD) at temperatures between 120 K and 520 K onto a supported model catalyst, which consisted of Pd nanoparticles grown on a well-ordered alumina film on NiAl(110). Adsorption and thermally induced surface reactions were followed by infrared reflection absorption spectroscopy (IRAS) and high-resolution X-ray photoelectron spectroscopy (HR-XPS) in combination with density functional theory (DFT) calculations. It was shown that, at 120 K, H-12-NEC adsorbs molecularly both on the Al2O3/NiAl(110) support and on the Pd particles. Initial activation of the molecule occurs through C-H bond scission at the 8a- and 9a-positions of the carbazole skeleton at temperatures above 170 K. Dehydrogenation successively proceeds with increasing temperature. Around 350 K, breakage of one C-N bond occurs accompanied by further dehydrogenation of the carbon skeleton. The decomposition intermediates reside on the surface up to 500 K. At higher temperatures, further decay to small fragments and atomic species is observed. These species block most of the absorption sites on the Pd particles, but can be oxidatively removed by heating in oxygen at 600 K, fully restoring the original adsorption properties of the model catalyst.}, author = {Sobota, Marek and Nikiforidis, Ioannis and Amende, Maximilian and Sanmartίn Zanón, Beatriz and Staudt, Thorsten and Höfert, Oliver and Lykhach, Yaroslava and Papp, Christian and Hieringer, Wolfgang and Laurin, Mathias and Assenbaum, Daniel and Wasserscheid, Peter and Steinrück, Hans-Peter and Görling, Andreas and Libuda, Jörg}, doi = {10.1002/chem.201101311}, faupublication = {yes}, journal = {Chemistry - A European Journal}, keywords = {density functional calculations;IR spectroscopy;liquid organic hydrogen carriers;photo-electron spectroscopy;supported catalysts}, pages = {11542-11552}, peerreviewed = {Yes}, title = {{Dehydrogenation} of {Dodecahydro}-{N}-ethylcarbazole on {Pd}/{Al2O3} {Model} {Catalysts}}, volume = {17}, year = {2011} } @article{faucris.120313864, abstract = {Sloshing hydrogen: Liquid organic hydrogen carriers are high-boiling organic molecules, which can be reversibly hydrogenated and dehydrogenated in catalytic processes and are, therefore, a promising chemical hydrogen storage material. One of the promising candidates is the pair N-ethylcarbazole/perhydro- N-ethylcarbazole (NEC/H-NEC). The dehydrogenation and possible side reactions on a Pt(111) surface are evaluated in unprecedented detail. Copyright &copy; 2013 WILEY-VCH Verlag GmbH &amp; Co. KGaA, Weinheim.}, author = {Gleichweit, Christoph and Amende, Maximilian and Schernich, Stefan and Zhao, Wei and Lorenz, Michael Peter Andreas and Höfert, Oliver and Brückner, Nicole and Wasserscheid, Peter and Libuda, Jörg and Steinrück, Hans-Peter and Papp, Christian}, doi = {10.1002/cssc.201300263}, faupublication = {yes}, journal = {Chemsuschem}, pages = {974-977}, peerreviewed = {Yes}, title = {{Dehydrogenation} of dodecahydro-{N}-ethylcarbazole on {Pt}(111)}, volume = {6}, year = {2013} } @article{faucris.228154987, abstract = {Among other N-heterocycles, indole and its substituted derivatives, such as methylindoles, are considered promising Liquid Organic Hydrogen Carriers (LOHCs) for the storage of renewable energy. We used X-ray photoelectron spectroscopy (XPS), temperature programmed desorption (TPD), and density-functional theory (DFT) to investigate the low temperature adsorption and consecutive dehydrogenation reaction during heating of 2-methylindole, 2-methylindoline, and 2-methyloctahydroindole on Pt(111) and their viability as the LOHC system. In the photoemission experiments, for all Hx-2-methylindoles, we find deprotonation at the NH bond starting between 240 and 300 K, resulting in a 2-methylindolide species. Simultaneously or before this reaction step, the dehydrogenation of 2-methyloctahydroindole via 2-methylindoline and 2-methylindole intermediates is observed. For 2-methyloctahydroindole, we also find π-allyl intermediates above 230 K. Starting at ∼390 K, decomposition of the remaining 2-methylindolide species takes place under the conditions of our surface science experiments. DFT calculations give insight into the relative energies of the various species, reaction intermediates, and their isomers both in the gas phase and on the Pt(111) surface.}, author = {Bachmann, Philipp and Steinhauer, Johann and Späth, Florian and Düll, Fabian and Bauer, Udo and Eschenbacher, Roman and Hemauer, Felix and Scheuermeyer, Marlene and Bösmann, Andreas and Büttner, Miriam and Neiß, Christian and Görling, Andreas and Wasserscheid, Peter and Steinrück, Hans-Peter and Papp, Christian}, doi = {10.1063/1.5112835}, faupublication = {yes}, journal = {Journal of Chemical Physics}, note = {CRIS-Team Scopus Importer:2019-10-22}, pages = {144711-}, peerreviewed = {Yes}, title = {{Dehydrogenation} of the liquid organic hydrogen carrier system 2-methylindole/2-methylindoline/2-methyloctahydroindole on {Pt}(111)}, volume = {151}, year = {2019} } @article{faucris.202402136, abstract = {Indole derivatives are considered as promising liquid organic hydrogen carriers for renewable energy storage. Using X-ray photoelectron spectroscopy, temperature-programmed desorption, and infrared reflection absorption spectroscopy, we investigated low-temperature adsorption and dehydrogenation during heating of indole, indoline, and octahydroindole on Pt(111). For all three molecules, we find deprotonation of the NH bond above 270 K, accompanied with dehydrogenation of indoline and octahydroindole via an indole intermediate, resulting in an indolide species above 300 K. For octahydroindole, we also find a side reaction yielding small amounts of a pi-allyl species between 170 and 450 K. Above 450 K, decomposition of the remaining indolide species takes place.}, author = {Bachmann, Philipp and Schwarz, Matthias and Steinhauer, Johann and Späth, Florian and Düll, Fabian and Bauer, Udo and Nascimento Silva, Thais and Mohr, Susanne and Hohner, Chantal and Scheuermeyer, Marlene and Wasserscheid, Peter and Libuda, Jörg and Steinrück, Hans-Peter and Papp, Christian}, doi = {10.1021/acs.jpcc.7b12625}, faupublication = {yes}, journal = {Journal of Physical Chemistry C}, pages = {4470-4479}, peerreviewed = {Yes}, title = {{Dehydrogenation} of the {Liquid} {Organic} {Hydrogen} {Carrier} {System} {Indole}/{Indoline}/{Octahydroindole} on {Pt}(111)}, volume = {122}, year = {2018} } @article{faucris.249335960, abstract = {Understanding the factors that control the demetalation of surface porphyrins at the solid-liquid interface is important as the molecular properties of porphyrins are largely determined by their metal centers. In this work, we used X-ray photoelectron spectroscopy (XPS) to follow the demetalation of Zn and Cd tetraphenylporphyrin molecules (ZnTPP and CdTPP) adsorbed as three-monolayer-thin multilayer films on Au(111), by exposing the molecular layers to acidic aqueous solutions. We found that porphyrin molecules at the solid-liquid interface are less prone to lose their metal center than molecules in solution. We propose that this behavior is due to either the incoming protons provided by the solution or the outgoing metal ion having to pass through the hydrophobic porphyrin multilayers where they cannot be solvated. Our results are relevant for the design of molecular devices based on porphyrin molecules adsorbed on solid surfaces. }, author = {Fernández, Cynthia C. and Franke, Matthias and Steinrück, Hans-Peter and Lytken, Ole and Williams, Federico J.}, doi = {10.1021/acs.langmuir.0c03197}, faupublication = {yes}, journal = {Langmuir}, month = {Jan}, note = {CRIS-Team Scopus Importer:2021-02-12}, pages = {852-857}, peerreviewed = {Yes}, title = {{Demetalation} of {Surface} {Porphyrins} at the {Solid}-{Liquid} {Interface}}, volume = {37}, year = {2021} } @article{faucris.108259844, abstract = {We measured the density and surface tension of 9 bis[(trifluoromethyl) sulfonyl]imide ([Tf N] )-based and 12 1-methyl-3- octylimidazolium ([C C Im] )-based ionic liquids (ILs) with the vibrating tube and the pendant drop method, respectively. This comprehensive set of ILs was chosen to probe the influence of the cations and anions on density and surface tension. When the alkyl chain length in the [C C Im][Tf N] series (n) 1, 2, 4, 6, 8, 10, 12) is increased, a decrease in density is observed. The surface tension initially also decreases but reaches a plateau for alkyl chain lengths greater than n) 8. Functionalizing the alkyl chains with ethylene glycol groups results in a higher density as well as a higher surface tension. For the dependence of density and surface tension on the chemical nature of the anion, relations are only found for subgroups of the studied ILs. Density and surface tension values are discussed with respect to intermolecular interactions and surface composition as determined by angle-resolved X-ray photoelectron spectroscopy (ARXPS). The absence of nonvolatile surface-active contaminants was proven by ARXPS. &copy; 2010 American Chemical Society.}, author = {Kolbeck, Claudia and Lehmann, Julia and Lovelock, Kevin and Cremer, Till and Paape, Natalia and Wasserscheid, Peter and Fröba, Andreas Paul and Maier, Florian and Steinrück, Hans-Peter}, doi = {10.1021/jp1068413}, faupublication = {yes}, journal = {Journal of Physical Chemistry B}, pages = {17025-17036}, peerreviewed = {Yes}, title = {{Density} and surface tension of ionic liquids}, volume = {114}, year = {2010} } @article{faucris.108495904, abstract = {O 1s and C 1s peak positions from high resolution X-ray photoelectron spectroscopy were used to determine adsorption sites of CO and CO coadsorbed with O and benzene, respectively, on Ni(111). Pure CO layers at 80 K were characterised by low energy electron diffraction and temperature programmed desorption and studied by X-ray photoelectron spectroscopy in a wide coverage range. For low coverages up to the well-known c(4 &times; 2) structure (&Theta; = 0.5 ML) the CO resides on threefold hollow sites. In the p(&radic;7 &times; &radic;7)R19&deg; structure (&Theta; = 0.57 ML) the on-top and bridge sites are occupied; for the compressed c(2&radic;3&times;4) rect structure (&Theta; = 0.62 ML) there is no clear preference for high symmetry adsorption sites. At room temperature the additional occupation of on-top and bridge sites is even observed at low coverages. In the p(2&radic;3 &times; 2&radic;3) R30&deg; (benzene+ 2CO) structure the CO resides most likely on threefold hollow sites with benzene molecules occupying the same adsorption sites. After the adsorption onto a p(2 &times; 2) oxygen layer at about 100 K the CO occupies two sites: on-top and bridge or hollow sites. If this layer is annealed to 260 K only the on-top sites are left on the surface. &copy; 1998 Elsevier Science B.V.}, author = {Held, Georg and Schuler, J. and Sklarek, Werner and Steinrück, Hans-Peter}, doi = {10.1016/S0039-6028(98)80020-4}, faupublication = {no}, journal = {Surface Science}, pages = {154-171}, peerreviewed = {Yes}, title = {{Determination} of adsorption sites of pure and coadsorbed {CO} on {Ni}(111) by high resolution {X}-ray photoelectron spectroscopy}, volume = {398}, year = {1998} } @article{faucris.115460884, abstract = {Abstract: We have studied the dehydrogenation of the liquid organic hydrogen carrier (LOHC) dicyclohexylmethane (DCHM) to diphenylmethane (DPM) and its side reactions on a Pd(111) single crystal surface. The adsorption and thermal evolution of both DPM and DCHM was measured in situ in ultrahigh vacuum (UHV) using synchrotron radiation-based high-resolution X-ray photoelectron spectroscopy (HR-XPS). We found that after deposition at 170 K, the hydrogen-lean DPM undergoes C-H bond scission at the methylene bridge at 200 K and, starting at 360 K, complete dehydrogenation of the phenyl rings occurs. Above 600 K, atomic carbon incorporates into the Pd bulk. For the hydrogen-rich DCHM, the first stable dehydrogenation intermediate, a double &pi;-allylic species, forms already at 190 K. Until 340 K, further dehydrogenation of the phenyl rings and of the methylene bridge occurs, yielding the same intermediate that is formed upon heating of DPM to this temperature, that is, DPM dehydrogenated at the methylene bridge. The onset for the complete dehydrogenation of this intermediate occurs at a much higher temperature than after adsorption of DPM. This behavior is mainly attributed to coadsorbed hydrogen from DCHM dehydrogenation. The results are discussed in comparison to our previous study of DPM and DCHM on Pt(111) revealing strong material dependencies. Graphical Abstract: [Figure not available: see fulltext.]}, author = {Amende, Maximilian and Gleichweit, Christoph and Xu, Tao and Höfert, Oliver and Koch, Marcus and Wasserscheid, Peter and Steinrück, Hans-Peter and Papp, Christian and Libuda, Jörg}, doi = {10.1007/s10562-016-1711-z}, faupublication = {yes}, journal = {Catalysis Letters}, keywords = {Liquid organic hydrogen carrier; Model catalysis; X-ray photoelectron spectroscopy}, pages = {1-10}, peerreviewed = {unknown}, title = {{Dicyclohexylmethane} as a {Liquid} {Organic} {Hydrogen} {Carrier}: {A} {Model} {Study} on the {Dehydrogenation} {Mechanism} over {Pd}(111)}, year = {2016} } @article{faucris.241506327, author = {Bhuin, Radha Gobinda and Winter, Leonhard and Lexow, Matthias and Maier, Florian and Steinrück, Hans-Peter}, doi = {10.1002/ange.202005991}, faupublication = {yes}, journal = {Angewandte Chemie}, note = {CRIS-Team Scopus Importer:2020-08-14}, pages = {14536-14541}, peerreviewed = {Yes}, title = {{Die} dynamische {Wechselwirkung} von n-{Butan} mit {Imidazolium}-basierten ionischen {Flüssigkeiten}}, volume = {132}, year = {2020} } @article{faucris.107825564, abstract = {We address the dynamic behavior and the surface chemical bond of 2H-tetraphenylporphyrin (2HTPP) on Cu(111) around room temperature by variable-temperature scanning tunneling microscopy (STM) and X-ray photoelectron spectroscopy (XPS) in ultrahigh vacuum. Between 280 and 345 K, the molecules predominantly display unidirectional diffusion along one of the three densely packed substrate 〈110〉 directions, which is attributed to a high site selectivity of the adsorbate-substrate bond. Above 305 K, the diffusion direction is found to change occasionally by &plusmn;120&deg;. The activation barriers for the unidirectional diffusion and for rotation of the diffusion direction are determined to 0.71 &plusmn; 0.08 and 1.28 &plusmn; 0.12 eV, respectively. XPS shows that the iminic nitrogen atoms of 2HTPP interact strongly with the Cu surface. It is postulated that the local bonding situation is similar as in the initial complex (sitting-atop complex), which has previously been observed during the surface-confined in situ metalation of porphyrins. &copy; 2011 American Chemical Society.}, author = {Buchner, Florian and Xiao, Jie and Zillner, Elisabeth and Chen, Min and Röckert, Michael and Ditze, Stefanie and Stark, Michael Werner and Steinrück, Hans-Peter and Gottfried, Michael and Marbach, Hubertus}, doi = {10.1021/jp206675u}, faupublication = {yes}, journal = {Journal of Physical Chemistry C}, pages = {24172-24177}, peerreviewed = {Yes}, title = {{Diffusion}, rotation, and surface chemical bond of individual 2 {H}-tetraphenylporphyrin molecules on {Cu}(111)}, volume = {115}, year = {2011} } @article{faucris.286936410, abstract = {We investigated the surface tension and surface composition of various mixtures of the two ionic liquids (ILs) 1-methyl-3-octyl-imidazolium hexafluorophosphate [C8C1Im][PF6] and 1,3-bis(polyethylene glycol)imidazolium iodide [(mPEG2)2Im]I in the temperature range from 230 to 370 K under ultraclean vacuum conditions. The surface tension was measured using a newly developed apparatus, and the surface composition was determined by angle-resolved X-ray photoelectron spectroscopy (ARXPS). In the pure ILs, the alkyl chains of [C8C1Im][PF6] and the PEG chains of [(mPEG2)2Im]I are enriched at the IL/vacuum interface. In the mixtures, a strong selective surface enrichment of the alkyl chains occurs, which is most pronounced at low [C8C1Im][PF6] contents. For the surface tension, strong deviations from an ideal mixing behaviour take place. By applying a simple approach based on the surface composition of the mixtures as deduced from ARXPS, we are able to predict and reproduce the experimentally measured temperature-dependent surface tension values with astonishingly high accuracy.}, author = {Paap, Ulrike and Seidl, Vera and Meyer, Karsten and Maier, Florian and Steinrück, Hans-Peter}, doi = {10.3390/molecules27238561}, faupublication = {yes}, journal = {Molecules}, keywords = {angle-resolved X-ray photoelectron spectroscopy (ARXPS); ionic liquids; pendant drop (PD); surface composition; surface tension; ultra-high vacuum (UHV)}, note = {CRIS-Team Scopus Importer:2022-12-23}, peerreviewed = {Yes}, title = {{Direct} {Correlation} of {Surface} {Tension} and {Surface} {Composition} of {Ionic} {Liquid} {Mixtures}—{A} {Combined} {Vacuum} {Pendant} {Drop} and {Angle}-{Resolved} {X}-ray {Photoelectron} {Spectroscopy} {Study}}, volume = {27}, year = {2022} } @article{faucris.108295264, abstract = {An ordered monolayer of phthalocyanine on a silver(111) surface reacts with the stoichiometric amount of coadsorbed Fe atoms to form iron(II)- phthalocyanine. This surface-confined redox reaction was studied with X-ray photoelectron spectroscopy (XPS) and scanning tunneling microscopy (STM). The formation of iron-(II)-phthalocyanine was confirmed by comparison with the directly deposited complex. No side reactions such as the coordination of Fe atoms on the peripheral nitrogen atoms of the phthalocyanine molecules were observed. &copy; 2008 American Chemical Society.}, author = {Bai, Yun and Buchner, Florian and Wendahl, Matthew T. and Kellner, Ina and Bayer, Andreas and Steinrück, Hans-Peter and Marbach, Hubertus and Gottfried, Michael}, doi = {10.1021/jp711122w}, faupublication = {yes}, journal = {Journal of Physical Chemistry C}, pages = {6087-6092}, peerreviewed = {Yes}, title = {{Direct} metalation of a phthalocyanine monolayer on {Ag}(111) with coadsorbed iron atoms}, volume = {112}, year = {2008} } @article{faucris.108332444, abstract = {We demonstrate that well-defined monolayers of a metal complex on a surface can be prepared by direct vapor deposition of the metal atoms on monolayers of the ligand. In particular, ordered monolayers of adsorbed tetraphenylporphyrin (2H-TPP) on a silver surface were exposed to cobalt vapors, resulting in the complexation of the metal by the porphyrin. The formation of the metal complexes was monitored by means of X-ray photoelectron spectroscopy (XPS), which reveals that this metalation reaction leads to a chemical equivalence of all four nitrogen atoms. The described in situ metalation provides a convenient way to produce adsorbed monolayers of more reactive (e.g., air- or solvent-sensitive) or thermally unstable metalloporphyrins that are difficult to evaporate or even to obtain as pure compounds at room temperature. Copyright &copy; 2006 American Chemical Society.}, author = {Gottfried, Michael and Flechtner, Ken and Kretschmann, Andreas and Lukasczyk, Thomas and Steinrück, Hans-Peter}, doi = {10.1021/ja0610333}, faupublication = {yes}, journal = {Journal of the American Chemical Society}, pages = {5644-5645}, peerreviewed = {Yes}, title = {{Direct} synthesis of a metalloporphyrin complex on a surface}, volume = {128}, year = {2006} } @article{faucris.120340044, abstract = {We have studied the dissociation and oxidation of methanol on the pure and oxygen-precovered Cu(1 1 0) surface using high resolution X-ray photoelectron spectroscopy (HRXPS) which allows the identification and quantification of reaction intermediates after various annealing steps while they are still on the surface. At 100 K methanol adsorbs molecularly on the clean Cu(1 1 0) surface. Successive annealing causes dissociation into methoxy and formaldehyde around 200 K before eventually all molecular species desorb from the surface. On the oxygen-precovered surface (0.25 ML O) methanol is oxidized on the expense of the preadsorbed oxygen. The analysis of the HRXPS data shows that there are at least three intermediate molecular species present on the surface, most likely methoxy, formaldehyde, and formate. © 2002 Elsevier Science B.V. All rights reserve}, author = {Ammon, Christian and Bayer, Andreas and Held, Georg and Richter, B. and Schmidt, Th. and Steinrück, Hans-Peter}, doi = {10.1016/S0039-6028(02)01361-4}, faupublication = {yes}, journal = {Surface Science}, pages = {845-850}, peerreviewed = {Yes}, title = {{Dissociation} and oxidation of methanol on {Cu}(110)}, volume = {507-510}, year = {2002} } @article{faucris.124146924, author = {Kirschner, Johannes and Wang, Zhenxing and Eigler, Siegfried and Steinrück, Hans-Peter and Jäger, Christof and Clark, Timothy and Hirsch, Andreas and Halik, Marcus}, doi = {10.1039/C4NR02527J}, faupublication = {yes}, journal = {Nanoscale}, pages = {11344-11350}, peerreviewed = {Yes}, title = {{Driving} forces for the self-assembly of graphene oxide on organic monolayers}, url = {http://pubs.rsc.org/en/content/articlelanding/2014/nr/c4nr02527j#!divAbstract}, volume = {6}, year = {2014} } @article{faucris.110162624, abstract = {The investigation of liquid surfaces and interfaces with the powerful toolbox of ultra-high vacuum (UHV)-based surface science techniques generally has to overcome the issue of liquid evaporation within the vacuum system. In the last decade, however, new classes of liquids with negligible vapor pressure at room temperature-in particular, ionic liquids (ILs)-have emerged for surface science studies. It has been demonstrated that particularly angle-resolved X-ray Photoelectron Spectroscopy (ARXPS) allows for investigating phenomena that occur at gas-liquid and liquid-solid interfaces on the molecular level. The results are not only relevant for IL systems but also for liquids in general. In all of these previous ARXPS studies, the sample holder had to be tilted in order to change the polar detection angle of emitted photoelectrons, which restricted the liquid systems to very thin viscous IL films coating a flat solid support. We now report on the concept and realization of a new and unique laboratory &quot;Dual Analyzer System for Surface Analysis (DASSA)&quot; which enables fast ARXPS, UV photoelectron spectroscopy, imaging XPS, and low-energy ion scattering at the horizontal surface plane of macroscopically thick non-volatile liquid samples. It comprises a UHV chamber equipped with two electron analyzers mounted for simultaneous measurements in 0 degrees and 80 degrees emission relative to the surface normal. The performance of DASSA on a first macroscopic liquid system will be demonstrated. (C) 2016 AIP Publishing LLC.}, author = {Niedermaier, Inga and Kolbeck, Claudia and Steinrück, Hans-Peter and Maier, Florian}, doi = {10.1063/1.4942943}, faupublication = {yes}, journal = {Review of Scientific Instruments}, peerreviewed = {Yes}, title = {{Dual} analyzer system for surface analysis dedicated for angle-resolved photoelectron spectroscopy at liquid surfaces and interfaces}, volume = {87}, year = {2016} } @article{faucris.109606244, abstract = {The effect of the nature of the support and the promotion achieved by a Rh additive on Co-based catalysts in the ethanol steam reforming reaction were studied. The catalysts with 2% Co loading were characterized by temperature-programmed reduction (TPR) and X-ray photoelectron spectroscopy (XPS). In situ diffuse reflectance Fourier-transform infrared spectroscopy (DRIFTS) identified the surface intermediates formed during the reaction, whereas gas phase products were detected by gas chromatography (GC). Upon heating in hydrogen to 773 K, cobalt could not be reduced to Co on alumina, but on silica the reduction was almost complete. On ceria, half of the Co could be reduced to the metallic state. By the presence of a small amount (0.1%) of Rh promoter, the reduction of both cobalt and ceria was greatly enhanced. For Co on the acidic AlO support, the dehydration mechanism was dominant, although on the basic CeO support, a significant amount of hydrogen was also formed. Addition of a small amount of Rh as promoter to the Co/CeO catalyst resulted in a significant further increase in the hydrogen selectivity. &copy; 2014 American Chemical Society.}, author = {Ferencz, Zs. and Erdohelyi, A. and Baan, K. and Oszko, A. and Ovari, L. and Konya, Zoltan and Papp, Christian and Steinrück, Hans-Peter and Kiss, J.}, doi = {10.1021/cs500045z}, faupublication = {yes}, journal = {ACS Catalysis}, pages = {1205-1218}, peerreviewed = {unknown}, title = {{Effects} of support and {Rh} additive on co-based catalysts in the ethanol steam reforming reaction}, volume = {4}, year = {2014} } @article{faucris.117434064, abstract = {The autocatalytic growth of arbitrarily shaped nanostructures fabricated by electron beam-induced deposition (EBID) and electron beam-induced surface activation (EBISA) is studied for two precursors: iron pentacarbonyl, Fe(CO)(5), and cobalt tricarbonyl nitrosyl, Co(CO)(3)NO. Different deposits are prepared on silicon nitride membranes and silicon wafers under ultrahigh vacuum conditions, and are studied by scanning electron microscopy (SEM) and scanning transmission X-ray microscopy (STXM), including near edge X-ray absorption fine structure (NEXAFS) spectroscopy. It has previously been shown that Fe(CO)(5) decomposes autocatalytically on Fe seed layers (EBID) and on certain electron beam-activated surfaces, yielding high purity, polycrystalline Fe nanostructures. In this contribution, we investigate the growth of structures from Co(CO)(3)NO and compare it to results obtained from Fe(CO)(5). Co(CO)(3)NO exhibits autocatalytic growth on Co-containing seed layers prepared by EBID using the same precursor. The growth yields granular, oxygen-, carbon- and nitrogen-containing deposits. In contrast to Fe(CO)(5) no decomposition on electron beam-activated surfaces is observed. In addition, we show that the autocatalytic growth of nanostructures from Co(CO)(3)NO can also be initiated by an Fe seed layer, which presents a novel approach to the fabrication of layered nanostructures.}, author = {Vollnhals, Florian and Drost, Martin and TU, Fan and Carrasco Burgos, Esther and Späth, Andreas and Fink, Rainer and Steinrück, Hans-Peter and Marbach, Hubertus}, doi = {10.3762/bjnano.5.129}, faupublication = {yes}, journal = {Beilstein Journal of Nanotechnology}, keywords = {autocatalytic growth;cobalt tricarbonyl nitrosyl;electron-beam induced deposition;nanofabrication;scanning transmission X-ray microscopy}, pages = {1175-1185}, peerreviewed = {Yes}, title = {{Electron}-beam induced deposition and autocatalytic decomposition of {Co}({CO})(3){NO}}, volume = {5}, year = {2014} } @article{faucris.107826884, abstract = {We have investigated the lithographic generation of TiO nanostructures on Si(100) via electron-beam-induced deposition (EBID) of titanium tetraisopropoxide (TTIP) in ultra-high vacuum (UHV) by scanning electron microscopy (SEM) and local Auger electron spectroscopy (AES). In addition, the fabricated nanostructures were also characterized ex situ via atomic force microscopy (AFM) under ambient conditions. In EBID, a highly focused electron beam is used to locally decompose precursor molecules and thereby to generate a deposit. A drawback of this nanofabrication technique is the unintended deposition of material in the vicinity of the impact position of the primary electron beam due to so-called proximity effects. Herein, we present a post-treatment procedure to deplete the unintended deposits by moderate sputtering after the deposition process. Moreover, we were able to observe the formation of pure titanium oxide nanocrystals (&gt;100 nm) in situ upon heating the sample in a well-defined oxygen atmosphere. While the nanocrystal growth for the as-deposited structures also occurs in the surroundings of the irradiated area due to proximity effects, it is limited to the pre-defined regions, if the sample was sputtered before heating the sample under oxygen atmosphere. The described two-step post-treatment procedure after EBID presents a new pathway for the fabrication of clean localized nanostructures. &copy; 2011 IOP Publishing Ltd.}, author = {Schirmer, Michael and Walz, Marie-Madeleine and Vollnhals, Florian and Lukasczyk, Thomas and Sandmann, Achim and Chen, C. and Steinrück, Hans-Peter and Marbach, Hubertus}, doi = {10.1088/0957-4484/22/8/085301}, faupublication = {yes}, journal = {Nanotechnology}, peerreviewed = {Yes}, title = {{Electron}-beam-induced deposition and post-treatment processes to locally generate clean titanium oxide nanostructures on {Si}(100)}, volume = {22}, year = {2011} } @article{faucris.108295704, abstract = {The generation of nanostructures with arbitrary shapes and well-defined chemical composition is still a challenge and targets the core of the fast-growing field of nanotechnology. One approach is the maskless nanofabrication technique of electron-beam-induced deposition (EBID). Up to now, the purity of these EBID structures has been rather poor. Here we demonstrate that by performing the EBID process solely under ultrahigh vacuum conditions, the lithographic generation of iron nanostructures on Si(100) with an unprecedented purity of higher than 95% is possible. One particular new aspect is the formation of EBID deposits with reduced size in a strain-induced diffusive process, resulting in deposits significantly smaller than 10 nm. &copy; 2008 Wiley-VCH Verlag GmbH &amp; Co.}, author = {Lukasczyk, Thomas and Schirmer, Michael and Steinrück, Hans-Peter and Marbach, Hubertus}, doi = {10.1002/smll.200701095}, faupublication = {yes}, journal = {Small}, pages = {841-846}, peerreviewed = {Yes}, title = {{Electron}-beam-induced deposition in ultrahigh vacuum: {Lithographic} fabrication of clean iron nanostructures}, volume = {4}, year = {2008} } @article{faucris.107810384, abstract = {We demonstrate how a focused electron beam can be used to chemically activate porphyrin layers on Ag(111) such that they become locally reactive toward the decomposition of iron pentacarbonyl, Fe(CO). This finding considerably expands the scope of electron beam induced surface activation (EBISA) and also has implications for electron beam induced deposition (EBID). The influence of the porphyrin layer thickness on both processes is studied in detail using scanning tunneling microscopy (STM) and scanning electron microscopy (SEM) as well as Auger electron spectroscopy (AES) and scanning Auger microscopy (SAM). While a closed monolayer of porphyrin molecules does exhibit some activity toward Fe(CO) decomposition after electron irradiation, a growth enhancement is found for bi- and multilayer films. This is attributed to a partial quenching of activated centers in the first layer due to the close proximity of the silver substrate. In addition, we demonstrate that the catalytic decomposition of gaseous Fe(CO) on Ag(111) can be effectively inhibited by introducing a densely packed monolayer of 2H-tetraphenylporphyrin (2HTPP) molecules. &copy; 2013 American Chemical Society.}, author = {Vollnhals, Florian and Wintrich, Patrick and Walz, Marie-Madeleine and Steinrück, Hans-Peter and Marbach, Hubertus}, doi = {10.1021/la4028095}, faupublication = {yes}, journal = {Langmuir}, pages = {12290-12297}, peerreviewed = {Yes}, title = {{Electron} beam induced surface activation of ultrathin porphyrin layers on {Ag}(111)}, volume = {29}, year = {2013} } @article{faucris.121401104, abstract = {Electron beam-induced surface activation (EBISA) has been used to grow wires of iron on rutile TiO(110)-(1 &times; 1) in ultrahigh vacuum. The wires have a width down to &sim;20 nm and hence have potential utility as interconnects on this dielectric substrate. Wire formation was achieved using an electron beam from a scanning electron microscope to activate the surface, which was subsequently exposed to Fe(CO). On the basis of scanning tunneling microscopy and Auger electron spectroscopy measurements, the activation mechanism involves electron beam-induced surface reduction and restructuring. &copy; 2013 American Chemical Society.}, author = {Vollnhals, Florian and Woolcot, Tom and Walz, Marie-Madeleine and Seiler, Steffen and Steinrück, Hans-Peter and Thornton, Geoff and Marbach, Hubertus}, doi = {10.1021/jp405640a}, faupublication = {yes}, journal = {Journal of Physical Chemistry C}, pages = {17674-17679}, peerreviewed = {Yes}, title = {{Electron} beam-induced writing of nanoscale iron wires on a functional metal oxide}, volume = {117}, year = {2013} } @article{faucris.108332664, abstract = {The k-resolved band structure of an epitaxially grown ZnSe(100) layer was investigated by angle resolved ultraviolet photoelectron spectroscopy combined with ab initio band structure calculations. The ZnSe layer 4 &mu;m thick was grown on a GaAs(100) substrate by molecular beam epitaxy and was transported to the German synchrotron facility BESSY under ultrahigh vacuum (UHV) conditions using a specially designed UHV transport box. The dispersion of the valence bands was measured along the &Gamma;X direction using photon energies between 15.2 and 44 eV. The experimental results are analyzed using the free-electron approximation as well as the calculated ZnSe bulk band structure for the final states.}, author = {Dröge, H. and Nagelstraßer, M. and Nürnberger, J. and Faschinger, W. and Fleszar, A. and Steinrück, Hans-Peter}, doi = {10.1016/S0039-6028(00)00153-9}, faupublication = {yes}, journal = {Surface Science}, pages = {477-482}, peerreviewed = {Yes}, title = {{Electronic} band structure of {ZnSe}(100)}, volume = {454}, year = {2000} } @article{faucris.108496784, abstract = {The band structure of a monolayer Cu on Ni(111) was studied both by angle resolved UV photoemission spectroscopy (ARUPS) and density functional (DF) calculations. The Cu 3d-bands at binding energies between 2 eV and 5 eV show a very pronounced k dispersion along the [112̄] and [1̄10] substrate directions, but no dispersion with k. This proves the two-dimensional character of the Cu 3d-bands. The periodicity of the bands coincides with the periodicity of the Ni(111) surface. The experimentally determined two-dimensional band structure of the pseudomorphic Cu monolayer on Ni(111) is in very good agreement with the results of DF calculations on the system. From this comparison we obtain detailed information about the Cu/Ni interaction and the k-dependent coupling of Cu and Ni bands.}, author = {Koschel, Herbert and Held, Georg and Trischberger, P. and Widdra, Wolf and Birkenheuer, U. and Steinrück, Hans-Peter}, doi = {10.1016/S0169-4332(98)00741-7}, faupublication = {yes}, journal = {Applied Surface Science}, pages = {18-22}, peerreviewed = {Yes}, title = {{Electronic} properties of a pseudomorphic {Cu}-layer on {Ni}(111)}, volume = {142}, year = {1999} } @article{faucris.108333544, abstract = {The growth and alloying of thin Zn layers on Pd(1 1 1) was investigated using X-ray and ultraviolet photoelectron spectroscopy as well as low energy electron diffraction and correlated with density functional calculations. At 105 K, the formation of a pseudomorphic Zn monolayer is observed. Upon heating this layer to 550 K or upon deposition of 1 ML at 550 K, an ordered p(2 × 1) PdZn surface alloy with a Pd:Zn ratio of ∼1:1 is formed, with a characteristic Pd 3d peak at a binding energy of ∼335.6 eV. For deposition of 3 ML Zn at 550 K or by heating 3 ML, deposited at low temperature, to 500 or 600 K, a PdZn alloy with a Pd:Zn ratio of again ∼1:1 is found in the surface region, with a Pd 3d peak at ∼335.9 eV; the direct preparation at 550 K leads to a more homogeneous and better ordered alloy. The valence band spectrum of this alloy with a low density of states at the Fermi level and pronounced maxima due to the "Pd 4d" band at ∼2.4 and 3.9 eV closely resembles the spectrum of Cu(1 1 1), in good agreement with the calculated density of states for a PdZn alloy of 1:1 stoichiometry. The shift of the "Pd 4d" band to higher binding energies as compared to Pd(1 1 1) indicates a charge transfer from Zn to the Pd 4d levels. Overall, the similarity between the ultraviolet photoelectron spectra for the PdZn alloy and for Cu(1 1 1) is taken as explanation for the similar chemical activity of both systems in methanol steam reforming. © 2005 Elsevier B.V. All rights reserve}, author = {Bayer, Andreas and Flechtner, Ken and Denecke, Reinhard and Steinrück, Hans-Peter and Neyman, Konstantin and Rösch, Notker}, doi = {10.1016/j.susc.2005.09.049}, faupublication = {yes}, journal = {Surface Science}, pages = {78-94}, peerreviewed = {Yes}, title = {{Electronic} properties of thin {Zn} layers on {Pd}(111) during growth and alloying}, volume = {600}, year = {2006} } @article{faucris.108336404, abstract = {The adsorption of benzene on a pseudomorphic Cu monolayer on Ru(0001) was studied by temperature-programmed desorption and angle-resolved UV photoelectron spectroscopy in combination with symmetry selection rules. Benzene is molecularly adsorbed on the pseudomorphic Cu monolayer on Ru(0001). Desorption of the first layer occurs in the temperature range between 155 and 340 K. In contrast to the clean Ru(0001) surface, no decomposition is observed upon heating. The analysis of the binding energies of the molecular benzene levels reveals a significant bonding shift of 1.1 eV of the benzene &pi; levels, which is nearly as large as the value of 1.4 eV for the strongly chemisorbed saturated benzene layer on Ru(0001). The benzene molecules are azimuthally oriented with the C-H bonds aligned along the [101̄0] direction. This geometry corresponds to an azimuthal rotation of 30&deg; as compared to that on the clean Ru(0001) surface.}, author = {Koschel, Herbert and Held, Georg and Steinrück, Hans-Peter}, doi = {10.1016/S0039-6028(00)00097-2}, faupublication = {yes}, journal = {Surface Science}, pages = {83-87}, peerreviewed = {Yes}, title = {{Electronic} structure and orientation of benzene adsorbed on a pseudomorphic {Cu} monolayer on {Ru}(0001)}, volume = {454}, year = {2000} } @article{faucris.108461804, abstract = {The electronic structure and the orientation of NO adsorbed on Ni(111) at 120 K was studied by angle resolved UPS using linearly polarized synchrotron radiation and a multichannel angle resolving electron analyzer. The layer investigated corresponds to a coverage of 0.5 ML and exhibits a c(4 &times; 2) LEED pattern with only twofold bridging sites being occupied. The binding energies for 4 \ ̃gs, 5 \ ̃gs and 1 \ ̃gP at the ḡG point are 15.1, 9.3 and ~7.5 eV, respectively; the 1 \ ̃gP level is very broad which may be due to splitting. The 2D band structure shows a dispersion of 0.3 eV for the 4 \ ̃gs and 0.6 eV for the 5 \ ̃gs level, indicative of lateral interactions within the adsorbed NO layer. The photon energy dependence of the photoionization cross sections of the 4 \ ̃gs, 5 \ ̃gs and 1 \ ̃gP NO molecular orbitais has been studied in the energy range 26 eV &le; ℏgw &le; 60 eV. The 4 \ ̃gs level shows a pronounced maximum at ℏ&omega; = 36 eV (E = 15 eV) that is peaked in the direction of the surface normal and is interpreted as a shape resonance. For the 5 \ ̃gs and 1 \ ̃gP levels no shape resonances are observed. Using dipole selection rules, it is demonstrated independently by initial state and final state arguments that in a c(4 &times; 2) layer the NO molecules are adsorbed with their molecular axis perpendicular to the surface. &copy; 1989.}, author = {Steinrück, Hans-Peter and Schneider, C. and Heimann, P.A. and Pache, T. and Umbach, E. and Menzel, Dietrich}, faupublication = {no}, journal = {Surface Science}, pages = {136-154}, peerreviewed = {Yes}, title = {{Electronic} structure and orientation of {NO} on {Ni}(111) studied by arups using synchrotron radiation}, url = {https://www.scopus.com/record/display.uri?eid=2-s2.0-0011177730&origin=inward}, volume = {208}, year = {1989} } @article{faucris.108500304, abstract = {Benzene adsorption on a single-domain Si(001)-(2 &times; 1) surface has been studied by thermal desorption spectroscopy (TPD) and angle-resolved photoelectron spectroscopy (ARUPS) using linearly polarized synchrotron radiation. Angle-resolved photoemission spectra for the saturated benzene layer exhibit well-defined polarization and azimuthal dependencies compatible with a flat-lying benzene molecule with local C symmetry. Based on these results two structure models are proposed. First-principles density functional cluster calculations have been performed for each of these structures. Total energy minimization and a detailed comparison of the experimental ARUPS spectra with the one-particle spectra of the model clusters leads to a 1,4-cyclohexadienelike adsorption complex with a flat-lying benzene molecule which is di-&sigma; bonded to the two dangling bonds of a single Si-Si surface dimer. Especially, one of the unoccupied 1e (&pi;*) orbitals of the free benzene molecule shifts down (by about 3 eV) and evolves into the highest occupied molecular orbital (HOMO) of the chemisorbed molecule. &copy; 1998 American Institute of Physics.}, author = {Gokhale, S. and Trischberger, P. and Menzel, Dietrich and Widdra, Wolf and Dröge, H. and Steinrück, Hans-Peter and Birkenheuer, U. and Gutdeutsch, U. and Rösch, Notker}, faupublication = {no}, journal = {Journal of Chemical Physics}, pages = {5554-5564}, peerreviewed = {Yes}, title = {{Electronic} structure of benzene adsorbed on single-domain {Si}(001)-(2 × 1): {A} combined experimental and theoretical study}, url = {https://www.scopus.com/record/display.uri?eid=2-s2.0-0001197411&origin=inward}, volume = {108}, year = {1998} } @article{faucris.108472144, abstract = {Mono- and multilayers of cyclohexane adsorbed on a Ni(111) surface have been studied by angle resolved UV photoelectron spectroscopy (ARUPS) using linearly polarized synchrotron radiation, temperature programmed desorption (TPD) and low energy electron diffraction (LEED). Cyclohexane is molecularly adsorbed on Ni(111) at temperatures below 200 K and desorbs without dehydrogenation. Desorption from the first layer exhibits zeroth-order desorption behavior indicative of desorption from two-dimensional islands. The first layer exhibits a well ordered ( 7 &times; 7)R19.1&deg; LEED structure starting at coverages of 0.04 ML up to the saturation coverage of 0.143 ML, also indicative of island formation. For cyclohexane in the first layer the binding energies of the various molecular levels are, apart from an overall shift to smaller values by 0.7 eV, within &plusmn; 0.1 eV identical to those of condensed cyclohexane. This absence of chemical shifts indicates that there is only very weak (if any) chemical interaction between cyclohexane and the Ni(111) surface. From the normal emission ARUPS spectra and symmetry selection rules we conclude that the symmetry of cyclohexane adsorbed on Ni(111) is lower than C . This is attributed to a slightly inclined adsorption geometry with intramolecular C symmetry of the adsorbed molecules. &copy; 1990.}, author = {Huber, W. and Zebisch, P. and Bornemann, T. and Steinrück, Hans-Peter}, doi = {10.1016/0039-6028(90)90235-Z}, faupublication = {no}, journal = {Surface Science}, pages = {353-362}, peerreviewed = {Yes}, title = {{Electronic} structure of cyclohexane on {Ni}(111)}, volume = {239}, year = {1990} } @article{faucris.113324464, abstract = {The adsorption of benzene on Ni(111) and Ru(001) was studied by ARUPS using linearly polarized synchrotron radiation for several pure benzene layers and for benzene coadsorbed with CO or NO. On both surfaces the benzene molecules are adsorbed parallel to the surface; the symmetry is reduced to C for Ni(111) and to C for Ru(001), in both cases independent of benzene coverage and the coadsorption of CO or NO. Overall the electronic structure of chemisorbed benzene is very similar for different benzene coverages and coadsorption of CO: only small uniform shifts in the electronic binding energies are observed which are attributed to electrostatic initial state changes. In contrast to CO, coadsorbed NO leads to differential shifts of the benzene molecular levels, indicating some additional changes in bonding. A pronounced maximum in the photoionization cross section of benzene adsorbed on Ni (111) at h{stroke}&omega; = 25 eV with the electron emission centered along the surface normal is attributed to a molecular shape resonance into an a final state. &copy; 1990.}, author = {Steinrück, Hans-Peter and Heimann, P.A. and Huber, W. and Jakob, P. and Pache, T. and Menzel, Dietrich}, faupublication = {no}, journal = {Journal of Electron Spectroscopy and Related Phenomena}, pages = {91-102}, peerreviewed = {Yes}, title = {{Electronic} structure, orientation and symmetry of benzene and benzene coadsorbed with {CO} and {NO} on {NI}(111) and {RU}(001)}, url = {https://www.scopus.com/record/display.uri?eid=2-s2.0-0005353059&origin=inward}, volume = {52}, year = {1990} } @article{faucris.120911384, abstract = {Figure Presented Beam me up: A novel two-step process allows iron nanostructures to be generated locally on SiO/Si at 300 K. The surface is first locally activated by an electron beam. Then the activated structures are exposed to [Fe(CO)], which decomposes and grows autocatalytically to give pure Fe nanocrystals. &copy; 2010 Wiley-VCH Verlag GmbH &amp; Co. KGaA, Weinheim.}, author = {Walz, Marie-Madeleine and Schirmer, Michael and Vollnhals, Florian and Lukasczyk, Thomas and Steinrück, Hans-Peter and Marbach, Hubertus}, doi = {10.1002/anie.201001308}, faupublication = {yes}, journal = {Angewandte Chemie International Edition}, pages = {4669-4673}, peerreviewed = {Yes}, title = {{Electrons} as "{Invisible} {Ink}": {Fabrication} of nanostructures by local electron beam induced activation of {SiOx}}, volume = {49}, year = {2010} } @article{faucris.120340704, abstract = {The formation of iron and iridium silicides was studied by means of highly resolved photoelectron spectroscopy of core and valence levels as well as by means of low-energy electron diffraction (LEED). The experiments were carried out at BESSY II in Berlin using synchrotron radiation for the photoemission studies. After evaporation of seven monolayers of Fe on Si(111) at room temperature and annealing to 410 K for 420 s, an ordering of the surface structure and the formation of an (1 &times; 1) LEED pattern is observed. Upon further heating to 500 K a strong change in both UPS and XPS spectra occurs. This behaviour is attributed to the formation of FeSi (1 &le; x &le; 2). After annealing of a thin Ir layer on Si(100) to 1130 K, a p(2 &times; 2) LEED pattern with respect to the silicon substrate is observed, which indicates the formation of a well-ordered surface compound. Comparison with the literature shows that the formation of an IrSi species is well known, but only an amorphous and a polycrystalline modification have been described upto now.}, author = {Probst, Marc and Denecke, Reinhard and Whelan, Caroline and Kinne, Martin and Borgmann, Dieter and Steinrück, Hans-Peter}, doi = {10.1002/sia.1402}, faupublication = {yes}, journal = {Surface and Interface Analysis}, pages = {744-748}, peerreviewed = {Yes}, title = {{Electron} spectroscopic studies of iron and iridium silicides}, volume = {34}, year = {2002} } @article{faucris.108337064, abstract = {The modification of polycrystalline MoO surfaces by vapor-deposited Co atoms was studied by means of X-ray photoelectron spectroscopy (XPS). Thin MoO layers react with evaporated Co atoms already at 90 K. At 300 K this process proceeds with a significantly higher reaction rate. Besides the Mo 3d signal, two new signals are observed in the Mo 3d XP spectra, which are assigned to Mo and Mo. Cobalt is initially oxidized to Co in the surface layer, but with increasing evaporation time the Co intensity steadily increases. During evaporation at a substrate temperature of 800 K, after an initial increase, a steady state of the Mo and Mo intensities develops. Thereafter at a constant evaporation rate no significant variations of the concentrations are detected within the escape depth of the photoelectrons. This behavior is attributed to interdiffusion processes from the surface and interface layers into the bulk. A satisfying fit of the Mo 3d spectra can only be obtained, when an additional Mo species is assumed, which is assigned to a cobalt molybdate.}, author = {Probst, Marc and Voß, Michael and Denecke, Reinhard and Viscido, L. and Heras, José M. and Borgmann, Dieter and Steinrück, Hans-Peter}, doi = {10.1016/S0368-2048(00)00238-3}, faupublication = {yes}, journal = {Journal of Electron Spectroscopy and Related Phenomena}, pages = {539-544}, peerreviewed = {Yes}, title = {{Electron} spectroscopic studies of vapor-deposited {Co} layers on {MoO3} surfaces}, year = {2001} } @article{faucris.109606464, abstract = {We introduce a new method for preparing ultrathin ionic liquid (IL) films on surfaces by means of electrospray ionization deposition (ESID) under ultraclean and well-defined ultra-high-vacuum (UHV) conditions. In contrast to physical vapor deposition (PVD) of ILs under UHV, ESID even allows deposition of ILs, which are prone to thermal decomposition. As proof of concept, we first investigated ultrathin [CCIm][TfN] (=1-methyl-3-octyl imidazolium bis(trifluoromethyl)imide) films on Au(111) by angle-resolved X-ray photoelectron spectroscopy (ARXPS). Films obtained by ESID are found to be virtually identical to films grown by standard PVD. Thereafter, ESID of [CCIm]Cl on Au(111) was studied as a first example of an IL that cannot be prepared as ultrathin film otherwise. [C CIm]Cl forms a wetting layer with a checkerboard arrangement with the cationic imidazolium ring and the chloride anion adsorbed next to each other on the substrate and the alkyl chain pointing toward vacuum. This arrangement within the wetting layer is similar to that observed for [CCIm][TfN], albeit with a higher degree of order of the alkyl chains. Further deposition of [CC Im]Cl leads to a pronounced island growth on top of the wetting layer, which is independently confirmed by ARXPS and atomic force microscopy. This behavior contrasts the growth behavior found for [CC Im][TfN], where layer-by-layer growth on top of the wetting layer is observed. The dramatic difference between both ILs is attributed to differences in the cation-anion interactions and in the degree of order in the wetting layer of the two ILs. &copy; 2014 American Chemical Society.}, author = {Rietzler, Florian and Piermaier, Marius and Deyko, Alexey and Steinrück, Hans-Peter and Maier, Florian}, doi = {10.1021/la404429q}, faupublication = {yes}, journal = {Langmuir}, pages = {1063-1071}, peerreviewed = {Yes}, title = {{Electrospray} ionization deposition of ultrathin ionic liquid films: [{C} {8C1Im}]{Cl} and [{C8C1Im}][{Tf} {2N}] on {Au}(111)}, volume = {30}, year = {2014} } @article{faucris.108503384, abstract = {The chemisorption of CO on ultrathin copper layers on Ru(001) has been investigated using a supersonic molecular beam and temperature programmed desorption. We are comparing the adsorption kinetics of CO on clean Ru(001) with those on a pseudomorphic Cu monolayer and a fully relaxed Cu(111) multilayer (&gt;40 layers) on Ru(001). For all three surfaces, a decrease of the initial sticking coefficient, S , with increasing beam energy was observed. For beam energies below 0.3 eV S is highest on the Cu monolayer, even though the binding energy of CO is significantly lower than on Ru(001). For higher energies S scales with the CO binding energy on the different substrates. The dependence of S of a low energy CO beam (0.09 eV) on the copper coverage is consistent with the Stranski-Krastanov growth mode of Cu on Ru(001) that is known from STM measurements. &copy; 1999 Elsevier Science B.V. All rights reserved.}, author = {Kneitz, Stefan and Gemeinhardt, J. and Koschel, Herbert and Held, Georg and Steinrück, Hans-Peter}, doi = {10.1016/S0039-6028(99)00167-3}, faupublication = {yes}, journal = {Surface Science}, pages = {27-31}, peerreviewed = {Yes}, title = {{Energy} and temperature dependent sticking coefficients of {CO} on ultrathin copper layers on {Ru} (001)}, year = {1999} } @article{faucris.108341464, abstract = {Experimentally determined band offsets of the CdSe/ZnTe/InAs(100) semiconductor heterostructures were presented. The semimagnetic system showed to behave very similar to the Mn-free model system. A stepwise alignment of the valence bands and in the ZnTe interlayer a 1.1 eV conduction band tunnel barrier were found.}, author = {Gleim, Thomas and Weinhardt, L. and Schmidt, Th. and Fink, Rainer and Heske, C. and Umbach, E. and Grabs, P. and Schmidt, G. and Molenkamp, L.W. and Richter, B. and Fleszar, A. and Steinrück, Hans-Peter}, doi = {10.1063/1.1519964}, faupublication = {yes}, journal = {Applied Physics Letters}, pages = {3813-3815}, peerreviewed = {Yes}, title = {{Energy} level alignment at zinc blende {Cd}({Mn}){Se}/{ZnTe}/{InAs}(100) interfaces}, volume = {81}, year = {2002} } @article{faucris.117544284, abstract = {We have investigated the electrochemically triggered cycloreversion of quadricyclane (QC) to norbornadiene (NBD), a system that holds the potential to combine both energy storage and conversion in a single molecule. Unambiguous voltammetric traces are obtained for pure NBD and pure QC, the latter a strained polycyclic isomer of the former. The difference in redox potentials is smaller than the energy difference between the neutral molecules. This is owing to a significant energy difference between the corresponding radical cations, as demonstrated by density functional theory (DFT) calculations. The vibrational modes of each pure compound are characterized experimentally in the fingerprint region and identified by DFT methods. Thermal and electrochemical transformations of NBD and QC are monitored insitu by IR spectroelectrochemical methods. The kinetics of the cycloreversion of QC to NBD, which is catalyzed by oxidizing equivalents, can be controlled by an applied electrode potential, which implies the ability to adjust in real time the release of thermal power stored in QC.}, author = {Brummel, Olaf and Besold, Daniel and Döpper, Tibor and Wu, Yanlin and Bochmann, Sebastian and Lazzari, Federica and Waidhas, Fabian and Bauer, Udo and Bachmann, Philipp and Papp, Christian and Steinrück, Hans-Peter and Görling, Andreas and Libuda, Jörg and Bachmann, Julien}, doi = {10.1002/cssc.201600127}, faupublication = {yes}, journal = {Chemsuschem}, keywords = {Infrared spectroscopy; Norbornadiene; Quadricyclane; Spectroelectrochemistry; Voltammetry}, pages = {1424-1432}, peerreviewed = {Yes}, title = {{Energy} {Storage} in {Strained} {Organic} {Molecules}: ({Spectro}){Electrochemical} {Characterization} of {Norbornadiene} and {Quadricyclane}}, volume = {9}, year = {2016} } @article{faucris.319054107, abstract = {Large domains of two-dimensional supramolecular porous nanostructures are interesting for various applications from electronics to biology. Here, we investigate the formation of Cu-coordinated networks on Cu(111) using scanning tunneling microscopy and density functional theory (DFT). We consider two molecules with three pyridyl end groups connected to a central benzene ring by either one or two phenyl groups, namely 1,3,5-tris[4-(pyridin)phenyl]benzene (TPyPB) and 1,3,5-tris[4-(pyridin)-[1,1’-biphenyl]benzene (TPyPPB), respectively. Upon deposition of TPyPB at room temperature, a honeycomb nanostructure forms, which is stabilized by Cu adatoms, as previously seen. Upon deposition at 400 K, the growth dynamics change, and molecules become trapped in the hexagonal pores. In contrast, deposition of TPyPPB at room temperature leads to vitreous structures, which rearrange at 400 K forming a low-defect and extended ordered honeycomb phase, which is also stabilized only in the presence of Cu adatoms. The DFT calculations for both honeycomb phases show an impressive agreement with the experimental results, considering the size of such structures. After annealing at 420 K, a complex flower-like structure composed of a mix of two- and three-fold coordinated Cu centers emerges. Further annealing to above 420 K leads to another new phase composed of a high molecular density motif, the so-called diamond phase.}, author = {Ceccatto, Alisson and Freiberger, Eva Marie and Waleska-Wellnhofer, Natalie and Jaekel, Simon and Mowbray, Duncan John and Papp, Christian and Steinrück, Hans-Peter and de Siervo, Abner}, doi = {10.1016/j.carbon.2024.118945}, faupublication = {yes}, journal = {Carbon}, keywords = {Cu(111); Metal coordination; Nanoporous organic network; On-surface synthesis; Scanning tunneling microscopy; TPyPB; TPyPPB}, note = {CRIS-Team Scopus Importer:2024-03-01}, peerreviewed = {Yes}, title = {{Engineering} large nanoporous networks with size and shape selected by appropriate precursors}, volume = {221}, year = {2024} } @article{faucris.253947479, abstract = {The behavior of ionic liquids (ILs) at charged interfaces is pivotal for their application in supercapacitors and electrochemical cells. Recently, we demonstrated for neat ILs that potential screening at polarized electrode interfaces shows a characteristic voltage dependence, as determined in situ by X-ray photoelectron spectroscopy. Herein, we use this fingerprint-type behavior to characterize the nature of the IL/electrode interfaces for IL mixtures of [C(8)C(1)Im][Tf2N] and [C(8)C(1)Im]Cl on Au and Pt electrodes. For Au, the IL/electrode interfaces are dominated by the Cl- anions, even down to a 0.1 mol% [C(8)C(1)Im]Cl content. In contrast, [Tf2N](-) anions enrich at the IL/Pt electrode interfaces down to 10 mol% [C(8)C(1)Im][Tf2N]; only at lower concentrations does a transition to Cl- enrichment occur. These mixture studies demonstrate that even small concentrations of another IL or contamination, e.g. remaining from synthesis, can strongly influence the situation at charged IL interfaces.}, author = {Shin, Sunghwan and Greco, Francesco and Maier, Florian and Steinrück, Hans-Peter}, doi = {10.1039/d0cp04811a}, faupublication = {yes}, journal = {Physical Chemistry Chemical Physics}, note = {CRIS-Team WoS Importer:2021-04-02}, peerreviewed = {Yes}, title = {{Enrichment} effects of ionic liquid mixtures at polarized electrode interfaces monitored by potential screening dagger}, year = {2021} } @article{faucris.272838749, author = {Niedermaier, Inga and Kolbeck, Claudia and Steinrück, Hans-Peter and Maier, Florian}, doi = {10.1063/1.4983571}, faupublication = {yes}, journal = {Review of Scientific Instruments}, note = {CRIS-Team Scopus Importer:2022-04-14}, pages = {059902-}, peerreviewed = {unknown}, title = {{Erratum}: "{Dual} analyzer system for surface analysis dedicated for angle-resolved photoelectron spectroscopy at liquid surfaces and interfaces" [{Rev}. {Sci}. {Instrum}. 87, 045105 (2016)}, volume = {88}, year = {2017} } @article{faucris.120336524, author = {Streber, Regine and Tränkenschuh, Barbara and Schöck, Johannes and Papp, Christian and Steinrück, Hans-Peter and Mcewen, J. -S. and Gaspard, P. and Denecke, R.}, doi = {10.1063/1.3257734}, faupublication = {yes}, journal = {Journal of Chemical Physics}, peerreviewed = {Yes}, title = {{Erratum}: {Interaction} between silver nanowires and {CO} on a stepped platinum surface ({Journal} of {Chemisty} {Physics} (2009) 131 (064702))}, volume = {131}, year = {2009} } @article{faucris.115186104, author = {Eiding, J. and Domcke, W. and Huber, W. and Steinrück, Hans-Peter}, doi = {10.1016/0009-2614(92)85393-O}, faupublication = {no}, journal = {Chemical Physics Letters}, note = {UnivIS-Import:2015-03-05:Pub.1991.nat.dchph.lpc2.erratu}, pages = {203}, peerreviewed = {Yes}, title = {{Erratum} of: "{Jahn}-{Teller} effect of the 2e2g level of chemisorbed benzene", {Chem}. {Phys}. {Lett}. 180 (1991), {Nr}. 1-2, {S}. 133-138}, volume = {191}, year = {1991} } @article{faucris.108263144, abstract = {The adsorption and thermal evolution of ethene (ethylene) on clean and oxygen precovered Ni(111) was investigated with high resolution x-ray photoelectron spectroscopy using synchrotron radiation at BESSY II. The high resolution spectra allow to unequivocally identify the local environment of individual carbon atoms. Upon adsorption at 110 K, ethene adsorbs in a geometry, where the two carbon atoms within the intact ethene molecule occupy nonequivalent sites, most likely hollow and on top; this new result unambiguously solves an old puzzle concerning the adsorption geometry of ethene on Ni(111). On the oxygen precovered surface a different adsorption geometry is found with both carbon atoms occupying equivalent hollow sites. Upon heating ethene on the clean surface, we can confirm the dehydrogenation to ethine (acetylene), which adsorbs in a geometry, where both carbon atoms occupy equivalent sites. On the oxygen precovered surface dehydrogenation of ethene is completely suppressed. For the identification of the adsorbed species and the quantitative analysis the vibrational fine structure of the x-ray photoelectron spectra was analyzed in detail. © 2010 American Institute of Physic}, author = {Lorenz, Michael Peter Andreas and Fuhrmann, Thomas and Streber, R. and Bayer, Andreas and Bebensee, Fabian and Gotterbarm, Karin and Kinne, Martin and Tränkenschuh, Barbara and Zhu, J. F. and Papp, Christian and Denecke, R. and Steinrück, Hans-Peter}, doi = {10.1063/1.3456732}, faupublication = {yes}, journal = {Journal of Chemical Physics}, pages = {014706 1-6}, peerreviewed = {Yes}, title = {{Ethene} adsorption and dehydrogenation on clean and oxygen precovered {Ni}(111) studied by high resolution x-ray photoelectron spectroscopy}, volume = {133}, year = {2010} } @article{faucris.118996284, author = {Weinelt, M. and Huber, W. and Zebisch, P. and Steinrück, Hans-Peter and Reichert, B. and Birkenheuer, U. and Rösch, Notker}, doi = {10.1103/PhysRevB.46.1675}, faupublication = {no}, journal = {Physical Review B}, pages = {1675-1686}, peerreviewed = {Yes}, title = {{ETHYLENE} {ADSORBED} {ON} {NI}(110) - {AN} {EXPERIMENTAL} {AND} {THEORETICAL} {DETERMINATION} {OF} {THE} 2-{DIMENSIONAL} {BAND}-{STRUCTURE}}, volume = {46}, year = {1992} } @article{faucris.239699828, abstract = {We present well-ordered Pt nanocluster arrays supported on the h-BN/Rh(111) Moiré as a model system for an ethylene dehydrogenation catalyst. Thereby, the h-BN nanomesh serves as a chemically inert eggbox-like template for clusters with a narrow size distribution. The thermal evolution of ethylene is investigated by synchrotron-based high-resolution in situ x-ray photoelectron spectroscopy on the Pt nanoclusters. We compare our results with data on Pt(111) and Pt(355). Interestingly, the Pt nanoclusters and Pt(355) behave very similarly. Both open a new reaction pathway via vinylidene in addition to the route via ethylidyne known for Pt(111). Due to the importance of coking in ethylene dehydrogenation on Pt catalysts, we also studied C2H4 adsorption and decomposition on carbon precovered Pt nanoclusters. While the amount of adsorbed ethylene decreases linearly with the carbon coverage, we found that edge sites are more affected than facet sites and that the vinylidene reaction pathway is effectively suppressed by carbon residues.}, author = {Düll, Fabian and Steinhauer, Johann and Späth, Florian and Bauer, Udo and Bachmann, Philipp and Steinrück, Hans-Peter and Wickert, Sandra and Denecke, Reinhard and Papp, Christian}, doi = {10.1063/5.0011616}, faupublication = {yes}, journal = {Journal of Chemical Physics}, note = {CRIS-Team Scopus Importer:2020-06-26}, pages = {224710-}, peerreviewed = {Yes}, title = {{Ethylene}: {Its} adsorption, reaction, and coking on {Pt}/h-{BN}/{Rh}(111) nanocluster arrays}, volume = {152}, year = {2020} } @article{faucris.108473904, abstract = {The adsorption of ethylene oxide (Et-O) on the reconstructed Pt(110) 1&times;2 surface has been studied by TPD, LEED, work function measurements, XPS, NEXAFS, and angle-resolved UPS using linearly polarized synchrotron radiation. At temperatures below 120 K Et-O adsorbs in molecular form with a saturation coverage of &asymp;0.5 monolayers. Upon heating molecular desorption occurs in the temperature range from 140 to 230 K with only minor decomposition (&le;0.02 monolayers), as concluded from TPD and XPS. From ARUPS and XPS the existence of two different Et-O species is inferred that are adsorbed at different adsorption sites with different local potential. The molecules are adsorbed with the oxygen end down, as concluded by the strong work function change upon adsorption (&Delta;&Phi;=-2.1 eV for the saturated layer). The polarization, polar angle and azimuthal dependence of the ARUPS spectra indicate a preferential orientation of both Et-O species with the CC axis oriented along the [110] direction and the molecular COC plane tilted towards the [001] (or [001]) azimuth. The orientation is, however, not perfect and the symmetry of the adsorption complex is C. The NEXAFS results are consistent with the proposed orientation. A detailed comparison to the results obtained for Et-O on Ni(110) in a previous study is given. &copy; 1993.}, author = {Weinelt, M. and Zebisch, P. and Steinrück, Hans-Peter}, faupublication = {no}, journal = {Chemical Physics}, pages = {321-336}, peerreviewed = {Yes}, title = {{Ethylene} oxide on {Pt}(110) 1×2. {A} multimethod investigation}, url = {https://www.scopus.com/record/display.uri?eid=2-s2.0-6144286459&origin=inward}, volume = {177}, year = {1993} } @article{faucris.121297704, abstract = {The influence of oxygen (O ) and carbon monoxide (CO) on Au nanoparticles supported on TiO (1 1 0) in the size range of 2-3 nm has been studied using X-ray photoelectron spectroscopy (XPS) and in situ (high pressure) XPS at 300 K for O and/or CO pressures of 0.1-1 mbar. These experiments were aimed at revisiting Au 4f core level shifts as reported in the literature and most importantly, to establish the dependence of the core-level shifts on the knowledge that there exists a maximum in reactivity for CO oxidation. Two samples were prepared with a coverage corresponding to that maximum (Au coverage 0.14-0.2 ML, particle size estimated to &sim;2-2.5 nm) while a third sample was expected to be less reactive (Au coverage 0.4 ML, particle size estimated to &sim;3.3 nm). At elevated O pressures, a new Au 4f component at higher binding energy (2.4-2.6 eV relative to the Au(0) bulk signal) evolved at all particle sizes. Its appearance was attributed to a radiation-induced activation of oxygen and simultaneous oxidation of gold. The activation was much more efficient on the &sim;2-2.5 nm particles. The relative intensity of the oxide component depended strongly on O pressure and, thus, on the equilibrium coverage of O . While not present in 0.1 mbar O regardless of exposure time and particle size, it dominated the Au 4f spectrum of particles &sim;2-2.5 nm in size at 1 mbar oxygen pressure. This pressure-dependent formation reconciles previously conflicting XPS data. Finally, the activated oxygen species were very reactive toward CO as manifested by the rapid disappearance of the new Au 4f component in a 1:1 mixture of CO and O . The rates of evolution and consumption of this component were found to depend on gold coverage (and thus, particle size) and were highest for the smaller particles. &copy; 2011 Elsevier B.V. All rights reserved.}, author = {Dumbuya, K. and Cabailh, G. and Lazzari, R. and Jupille, J. and Ringel, Lorenz and Pistor, Martina and Lytken, Ole and Steinrück, Hans-Peter and Gottfried, Michael}, doi = {10.1016/j.cattod.2011.09.035}, faupublication = {yes}, journal = {Catalysis Today}, pages = {20-25}, peerreviewed = {Yes}, title = {{Evidence} for an active oxygen species on {Au}/{TiO} 2(1 1 0) model catalysts during investigation with in situ {X}-ray photoelectron spectroscopy}, volume = {181}, year = {2012} } @article{faucris.123155384, abstract = {Using X-ray photoelectron spectroscopy (XPS), we demonstrate that free-base tetraphenylporphyrin (2HTPP) on Ag(1 0 0) forms a theoretically predicted adcomplex with post-deposited iron at 100 K. The formation of the adcomplex, as a precursor for metalation, can be deduced from the N Is spectra showing clearly not-metalated 2HTPP molecules, but with strongly shifted iminic nitrogen peaks, caused by the interaction of the iminic nitrogen atoms with the Fe adatoms. (C) 2015 Elsevier B.V. All rights reserved.}, author = {Röckert, Michael and Franke, Matthias and Tariq, Quratulain and Steinrück, Hans-Peter and Lytken, Ole}, doi = {10.1016/j.cplett.2015.05.031}, faupublication = {yes}, journal = {Chemical Physics Letters}, pages = {60-62}, peerreviewed = {Yes}, title = {{Evidence} for a precursor adcomplex during the metalation of {2HTPP} with iron on {Ag}(100)}, volume = {635}, year = {2015} } @article{faucris.306949083, abstract = {Two-dimensional conjugated polymers (2DCPs), composed of multiple strands of linear conjugated polymers with extended in-plane π-conjugation, are emerging crystalline semiconducting polymers for organic (opto)electronics. They are represented by two-dimensional π-conjugated covalent organic frameworks, which typically suffer from poor π-conjugation and thus low charge carrier mobilities. Here we overcome this limitation by demonstrating two semiconducting phthalocyanine-based poly(benzimidazobenzophenanthroline)-ladder-type 2DCPs (2DCP-MPc, with M = Cu or Ni), which are constructed from octaaminophthalocyaninato metal(ii) and naphthalenetetracarboxylic dianhydride by polycondensation under solvothermal conditions. The 2DCP-MPcs exhibit optical bandgaps of ~1.3 eV with highly delocalized π-electrons. Density functional theory calculations unveil strongly dispersive energy bands with small electron–hole reduced effective masses of ~0.15m <inf>0</inf> for the layer-stacked 2DCP-MPcs. Terahertz spectroscopy reveals the band transport of Drude-type free carriers in 2DCP-MPcs with exceptionally high sum mobility of electrons and holes of ~970 cm² V⁻¹ s⁻¹ at room temperature, surpassing that of the reported linear conjugated polymers and 2DCPs. This work highlights the critical role of effective conjugation in enhancing the charge transport properties of 2DCPs and the great potential of high-mobility 2DCPs for future (opto)electronics.}, author = {Wang, Mingchao and Fu, Shuai and Petkov, Petko and Fu, Yubin and Zhang, Zhitao and Liu, Yannan and Ma, Ji and Chen, Guangbo and Gali, Sai Manoj and Gao, Lei and Lu, Yang and Paasch, Silvia and Zhong, Haixia and Steinrück, Hans-Peter and Cánovas, Enrique and Brunner, Eike and Beljonne, David and Bonn, Mischa and Wang, Hai I. and Dong, Renhao and Feng, Xinliang}, doi = {10.1038/s41563-023-01581-6}, faupublication = {yes}, journal = {Nature Materials}, note = {CRIS-Team Scopus Importer:2023-06-30}, peerreviewed = {Yes}, title = {{Exceptionally} high charge mobility in phthalocyanine-based poly(benzimidazobenzophenanthroline)-ladder-type two-dimensional conjugated polymers}, year = {2023} } @article{faucris.108474124, abstract = {Using synchrotron radiation, Auger electron, and H/D -ion yields have been studied at and above the O 1s excitation energies for condensed HO/DO layers of varying thickness, and for two reproducible adsorbate layers (so-called bilayers and monolayers) on Ru(001). Decay electron spectra as well as polarization dependences, angular distributions, and energy distributions of desorbing ions have been investigated. For polarizations with sufficient E component perpendicular to the surface, a sharp peak in the H NEXAFS spectrum is seen for all layers which has no direct counterpart in the Auger NEXAFS spectra, and whose intensity maximizes for E oriented in the detection direction. This observation is interpreted as due to the 1a &rarr; 4a core-to-bound transition of the surface molecules whose final state decays electronically and dissociates on comparable time scales. This appears to have the consequence that the symmetry of the coupled excitation is different from that expected for the primary photoabsorption process. There appears also to be an influence of hydrogen bonding on these effects. Similarities and differences between the various layers investigated are also analyzed. &copy; 1990 American Institute of Physics.}, author = {Coulman, D. and Puschmann, A. and Höfer, U. and Steinrück, Hans-Peter and Wurth, W. and Feulner, P. and Menzel, Dietrich}, doi = {10.1063/1.459560}, faupublication = {no}, journal = {Journal of Chemical Physics}, pages = {58-75}, peerreviewed = {Yes}, title = {{Excitation}, deexcitation, and fragmentation in the core region of condensed and adsorbed water}, volume = {93}, year = {1990} } @article{faucris.319063835, abstract = {The interaction of metal complexes with ionic liquids, with a particular focus on the stability and surface concentration of the metal centers, is crucial in applications involving catalysts based on supported ionic liquids. In this study, we synthesized the complexes [Ru(tpy)(bpy)Cl][PF<inf>6</inf>] and [Ru(tpy)(dcb)Cl][PF<inf>6</inf>] (tpy = 2,2′,2′′-terpyridine, bpy = 2,2′-bipyridine, dcb = 4,4′-dicarboxy-2,2′-bipyridine) and we prepared solutions using the ionic liquids (ILs) 1-ethyl-3-methylimidazolium acetate [C<inf>2</inf>C<inf>1</inf>Im][OAc] and 1-butyl-3-methylimidazolium hexafluorophosphate [C<inf>4</inf>C<inf>1</inf>Im][PF<inf>6</inf>]. The chemical environment of the Ru(ii) metal center and the interfacial behavior of the complexes in the different IL solutions were determined using angle-resolved X-ray photoelectron spectroscopy (ARXPS). In [C<inf>4</inf>C<inf>1</inf>Im][PF<inf>6</inf>], [Ru(tpy)(bpy)Cl][PF<inf>6</inf>] maintains its chemical structure, while in [C<inf>2</inf>C<inf>1</inf>Im][OAc], partial changes in the chemical environment of the Ru center are indicated by XPS, likely due to ligand exchange. The presence of carboxylic acid functional groups in the bipyridyl ligand seems to inhibit this ligand exchange. The investigated complexes do not exhibit surface activity but are depleted from the IL/gas interface. These findings hold significance for the design of new supported ionic liquid phase catalysts based on Ru complexes.}, author = {Hemmeter, Daniel and Merlinsky, Luciano Sanchez and Baraldo, Luis M. and Maier, Florian and Williams, Federico J. and Steinrück, Hans-Peter}, doi = {10.1039/d4cp00247d}, faupublication = {yes}, journal = {Physical Chemistry Chemical Physics}, note = {CRIS-Team Scopus Importer:2024-03-01}, peerreviewed = {Yes}, title = {{Exploring} the interfacial behavior of ruthenium complexes in ionic liquids: implications for supported ionic liquid phase catalysts}, year = {2024} } @article{faucris.107827104, abstract = {We report on the stepwise generation of layered nanostructures via electron beam induced deposition (EBID) using organometallic precursor molecules in ultra-high vacuum (UHV). In a first step a metallic iron line structure was produced using iron pentacarbonyl; in a second step this nanostructure was then locally capped with a 2-3nm thin titanium oxide-containing film fabricated from titanium tetraisopropoxide. The chemical composition of the deposited layers was analyzed by spatially resolved Auger electron spectroscopy. With spatially resolved x-ray absorption spectroscopy at the Fe L edge, it was demonstrated that the thin capping layer prevents the iron structure from oxidation upon exposure to air. &copy; 2011 IOP Publishing Ltd.}, author = {Schirmer, Michael and Walz, Marie-Madeleine and Papp, Christian and Kronast, F. and Gray, A.X. and Balke, B. and Cramm, S. and Fadley, C.S. and Steinrück, Hans-Peter and Marbach, Hubertus}, doi = {10.1088/0957-4484/22/47/475304}, faupublication = {yes}, journal = {Nanotechnology}, peerreviewed = {Yes}, title = {{Fabrication} of layered nanostructures by successive electron beam induced deposition with two precursors: {Protective} capping of metallic iron structures}, volume = {22}, year = {2011} } @article{faucris.121439824, abstract = {The change of the initial sticking coefficient for a Maxwellian beam of hydrogen on Ni(997) has been determined as a function of beam temperature and angle of incidence. At low temperatures adsorption is governed by the steps, at high temperatures adsorption on the terraces is more dominant. Adsorption on the terraces is probably an activated process whereas adsorption on the step sites is non-activated. There seems to be little diffusion of undissociated H between steps and terraces. &copy; 1985.}, author = {Karner, H. and Luger, M. and Steinrück, Hans-Peter and Winkler, A. and Rendulic, K.D.}, doi = {10.1016/0039-6028(85)90838-6}, faupublication = {no}, journal = {Surface Science}, pages = {641-644}, peerreviewed = {Yes}, title = {{Features} of hydrogen adsorption on a {Ni}(997) surface}, volume = {163}, year = {1985} } @article{faucris.211476455, abstract = {Group 15 elements in zero oxidation state (P, As, Sb and Bi), also called pnictogens, are rarely used in catalysis due to the difficulties associated in preparing well-structured and stable materials. Here, we report on the synthesis of highly exfoliated, few layer 2D phosphorene and antimonene in zero oxidation state, suspended in an ionic liquid, with the native atoms ready to interact with external reagents while avoiding aerobic or aqueous decomposition pathways, and on their use as efficient catalysts for the alkylation of nucleophiles with esters. The few layer pnictogen material circumvents the extremely harsh reaction conditions associated to previous superacid-catalyzed alkylations, by enabling an alternative mechanism on surface, protected from the water and air by the ionic liquid. These 2D catalysts allow the alkylation of a variety of acid-sensitive organic molecules and giving synthetic relevancy to the use of simple esters as alkylating agents.}, author = {Lloret Segura, Vicente Josep and Angel Rivero-Crespo, Miguel and Alejandro Vidal-Moya, Jose and Wild, Stefan and Domenech-Carbo, Antonio and Heller, Bettina and Shin, Sunghwan and Steinrück, Hans-Peter and Maier, Florian and Hauke, Frank and Varela, Maria and Hirsch, Andreas and Leyva-Perez, Antonio and Abellan Saez, Gonzalo}, doi = {10.1038/s41467-018-08063-3}, faupublication = {yes}, journal = {Nature Communications}, month = {Jan}, note = {CRIS-Team WoS Importer:2019-02-21}, peerreviewed = {Yes}, title = {{Few} layer {2D} pnictogens catalyze the alkylation of soft nucleophiles with esters}, volume = {10}, year = {2019} } @article{faucris.108476544, abstract = {Angular distributions of S2p32 photoelectrons were measured for Ni(111)-p(2&times;2)S at seven kinetic energies between 130 and 322.5 eV. Using these data, the real space structure around the emitter is reconstructed using the multiple wave number phased-sum algorithm. The reconstructed images allow the unequivocal identification of the fcc adsorption site, with a distance from the S atoms to the top Ni layer of 1.6. This is, to our knowledge, the first example wherein the multiple wave number phased-sum method has successfully been applied to determine an adsorption site from experimental data. &copy; 1994 The American Physical Society.}, author = {Zharnikov, M. and Weinelt, M. and Zebisch, P. and Stichler, M. and Steinrück, Hans-Peter}, doi = {10.1103/PhysRevLett.73.3548}, faupublication = {no}, journal = {Physical Review Letters}, pages = {3548-3551}, peerreviewed = {Yes}, title = {{First} experimental determination of an adsorption site using multiple wave number photoelectron diffraction patterns}, volume = {73}, year = {1994} } @article{faucris.108615804, abstract = {Controlled patterning of graphene is an important task towards device fabrication and thus is the focus of current research activities. Graphene oxide (GO) is a solution-processible precursor of graphene. It can be patterned by thermal processing. However, thermal processing of GO leads to decomposition and CO2 formation. Alternatively, focused electron beam induced processing (FEBIP) techniques can be used to pattern graphene with high spatial resolution. Based on this approach, we explore FEBIP of GO deposited on SiO2. Using oxo-functionalized graphene (oxo-G) with an in-plane lattice defect density of 1% we are able to image the electron beam-induced effects by scanning Raman microscopy for the first time. Depending on electron energy (2-30 keV) and doses (50-800 mC m(-2)) either reduction of GO or formation of permanent lattice defects occurs. This result reflects a step towards controlled FEBIP processing of oxo-G.}, author = {Schindler, Severin and Vollnhals, Florian and Halbig, Christian Eberhard and Marbach, Hubertus and Steinrück, Hans-Peter and Papp, Christian and Eigler, Siegfried}, doi = {10.1039/c6cp08070g}, faupublication = {yes}, journal = {Physical Chemistry Chemical Physics}, month = {Jan}, pages = {2683-2686}, peerreviewed = {Yes}, title = {{Focused} electron beam based direct-write fabrication of graphene and amorphous carbon from oxo-functionalized graphene on silicon dioxide}, volume = {19}, year = {2017} } @article{faucris.284133876, abstract = {We studied the formation and surface behavior of Pt(II) and Pd(II) complexes with ligand systems derived from two nitrile-functionalized ionic liquids (ILs) in solution using angle-resolved X-ray photoelectron spectroscopy (ARXPS). These ligand systems enabled a high solubility of the metal complexes in IL solution. The complexes were prepared by simple ligand substitution under vacuum conditions in defined excess of the coordinating ILs, [C<inf>3</inf>CNC<inf>1</inf>Im][Tf<inf>2</inf>N] and [C<inf>1</inf>CNC<inf>1</inf>Pip][Tf<inf>2</inf>N], to immediately yield solutions of the final products. The ILs differ in the cationic head group and the chain length of the functionalized substituent. Our XPS measurements on the neat ILs gave insights in the electronic properties of the coordinating substituents revealing differences in donation capability and stability of the complexes. Investigations on the composition of the outermost surface layers using ARXPS revealed no surface affinity of the nitrile-functionalized chains in the neat ILs. Solutions of the formed complexes in the nitrile ILs showed homogeneous distribution of the solute at the surface with the heterocyclic moieties preferentially orientated towards the vacuum, while the metal centers are rather located further away from the IL/vacuum interface.}, author = {Hemmeter, Daniel and Paap, Ulrike and Taccardi, Nicola and Mehler, Julian and Schulz, Peter and Wasserscheid, Peter and Maier, Florian and Steinrück, Hans-Peter}, doi = {10.1002/cphc.202200391}, faupublication = {yes}, journal = {ChemPhysChem}, keywords = {catalysis; ionic liquids; organometallic chemistry; surface science; X-ray photoelectron spectroscopy}, note = {CRIS-Team Scopus Importer:2022-10-28}, peerreviewed = {Yes}, title = {{Formation} and {Surface} {Behavior} of {Pt} and {Pd} {Complexes} with {Ligand} {Systems} {Derived} from {Nitrile}-functionalized {Ionic} {Liquids} {Studied} by {XPS}}, year = {2022} } @article{faucris.108342564, abstract = {Thin chromiumoxide layers (&Theta; up to 10 ML) on Cu(1 1 1) were produced by evaporating chromium onto multilayers of water (DO) at 120 K. Their composition and structure were studied by X-ray photoelectron spectroscopy, low-energy electron diffraction and temperature programmed desorption. Annealing the sample to 750 K leads to a new type of chromium oxide CrO with a square two-dimensional lattice and a lattice constant of 2.70 &Aring;. It is stable upon heating up to 950 K. Further oxidation of this oxide layer in an oxygen atmosphere of 10 mbar leads to the formation of &alpha;-CrO oriented with its hexagonal (0 0 0 1) plane parallel to the surface. Adsorption/desorption experiments show that the square oxide surface is essentially unable to adsorb CO at 90 K which is in contrast to the hexagonal &alpha;-CrO surface. &copy; 2001 Elsevier Science B.V.}, author = {Pantförder, Jörg and Domnick, Ralph and Ammon, Christian and Held, Georg and Steinrück, Hans-Peter}, doi = {10.1016/S0039-6028(01)01001-9}, faupublication = {yes}, journal = {Surface Science}, pages = {73-83}, peerreviewed = {Yes}, title = {{Formation} of a new type of chromium oxide by deposition of chromium onto water precovered {Cu}(1 1 1)}, volume = {480}, year = {2001} } @article{faucris.240046863, abstract = {We investigated the adsorption of three related cyano-functionalized tetraphenyl porphyrin derivatives on Cu(111) by scanning tunneling microscopy (STM) in ultra-high vacuum (UHV) with the goal to identify the role of the cyano group and the central Cu atom for the intermolecular and supramolecular arrangement. The porphyrin derivatives studied were Cu-TCNPP, Cu-cisDCNPP, and 2H-cisDCNPP, that is, Cu-5,10,15,20-tetrakis-(p-cyano)-phenyl-porphyrin, Cu-meso-cis-di(p-cyano)-phenyl-porphyrin and 2H-meso-cis-di(p-cyano)-phenyl-porphyrin, respectively. Starting from different structures obtained after deposition at room temperature, all three molecules form the same long-range ordered hexagonal honeycomb-type structure with triangular pores and three molecules per unit cell. For the metal-free 2H-cisDCNPP, this occurs only after self-metalation upon heating. The structure-forming elements are pores with a distance of 3.1 nm, formed by triangles of porphyrins fused together by cyano-Cu-cyano interactions with Cu adatoms. This finding leads us to suggest that two cyano-phenyl groups in the "cis" position is the minimum prerequisite to form a highly ordered 2D porous molecular pattern. The experimental findings are supported by detailed density functional theory calculations to analyze the driving forces that lead to the formation of the porous hexagonal honeycomb-type structure.}, author = {Steinrück, Hans-Peter and Adhikari, Rajan and Siglreithmaier, Gretel and Gurrath, Martin and Meusel, Manuel and Kuliga, Jan and Lepper, Michael and Hölzel, Helen and Jux, Norbert and Meyer, Bernd and Marbach, Hubertus}, doi = {10.1002/chem.202001980}, faupublication = {yes}, journal = {Chemistry - A European Journal}, keywords = {porphyrins coordinated networks cyano functionalization scanning tunneling microscopy (STM) density-functional theory (DFT) calculations}, note = {CRIS-Team Scopus Importer:2020-07-03}, peerreviewed = {Yes}, title = {{Formation} of highly ordered molecular porous {2D} networks from cyano-functionalized porphyrins on {Cu}(111)}, year = {2020} } @article{faucris.108282944, abstract = {The adsorption of Ca on poly(3-hexylthiophene) (P3HT) has been studied by adsorption microcalorimetry, atomic beam/surface scattering, X-ray photoelectron spectroscopy (XPS), low-energy He ion scattering spectroscopy (LEIS), and first-principles calculations. The sticking probability of Ca on P3HT is initially 0.35 and increases to almost unity by 5 ML. A very high initial heat of adsorption in the first 0.02 ML (625-500 kJ/mol) is attributed to the reaction of Ca with defect sites or residual contamination. Between 0.1 and 0.5 ML, there is a high and nearly constant heat of adsorption of 405 kJ/mol, which we ascribe to Ca reacting with subsurface sulfur atoms from the thiophene rings of the polymer. This is supported by the absence of LEIS signal for Ca and the shift of the S 2p XPS binding energy by -2.8 eV for reacted S atoms. The heat of adsorption decreases above 0.6 ML coverage, reaching the sublimation enthalpy of Ca, 178 kJ/mol, by 4 ML. This is attributed to the formation of Ca nanoparticles and eventually a continuous solid Ca film, on top of the polymer. LEIS and XPS measurements, which show only a slow increase of the signals related to solid Ca, support this model. Incoming Ca atoms are subject to a kinetic competition between diffusing into the polymer to react with subsurface thiophene units versus forming or adding to three-dimensional Ca clusters on the surface. At &sim;1.6 ML Ca coverage, Ca atoms have similar probabilities for either process, with the former dominating at lower coverage. Ultimately about 1.6 ML of Ca (1.2 x 10 atoms/cm) reacts with S atoms, corresponding to a reacted depth of &sim;3 nm, or nearly five monomerunit layers. Density-functional theory calculations confirm that the heat of reaction and the shift of the S 2p signal are consistent with Ca abstracting S from the thiophene rings to form small CaS clusters. &copy; 2009 American Chemical Society.}, author = {Zhu, Junfa and Bebensee, Fabian and Hieringer, Wolfgang and Zhao, Wei and Baricuatro, J. H. and Farmer, Jason A. and Bai, Yun and Steinrück, Hans-Peter and Gottfried, Michael and Campbell, C. T.}, doi = {10.1021/ja904844c}, faupublication = {yes}, journal = {Journal of the American Chemical Society}, pages = {13498-13507}, peerreviewed = {Yes}, title = {{Formation} of the calcium/poly(3-hexylthiophene) interface: {Structure} and energetics}, volume = {131}, year = {2009} } @article{faucris.108344104, abstract = {We have investigated the underlying electronic and structural effects of the previously published influence of a Te substrate pretreatment on the heterovalent ZnSe/GaAs(100) interface [Appl. Phys. Lett. 78 (2001) 1867]. For this purpose, photoelectron spectroscopy and density functional theory calculations were employed. To determine the valence band maximum accurately, the choice of suitable photon energies to maximize the contribution from the &Gamma;-point as well as a variation of the k-vector by measuring under selected angles is investigated. We discuss the resulting band offsets with respect to the atomic interface structure and to the broadening of core level line shapes. The theoretical investigations focus on the effect of replacing Se by Te atoms at the interface, particularly in view of the lattice structure and the band offsets. We find that Te helps to establish a group-VI-rich interface, thus lowering the valence band offset, while maintaining a good crystal quality by acting as a diffusion barrier for Se atoms. &copy; 2003 Elsevier Science B.V. All rights reserved.}, author = {Gleim, Thomas and Heske, C. and Umbach, E. and Schumacher, C. and Gundel, S. and Faschinger, W. and Fleszar, A. and Ammon, Christian and Probst, Marc and Steinrück, Hans-Peter}, doi = {10.1016/S0039-6028(03)00439-4}, faupublication = {yes}, journal = {Surface Science}, pages = {77-85}, peerreviewed = {Yes}, title = {{Formation} of the {ZnSe}/({Te}/){GaAs}( 1 0 0 ) heterojunction}, volume = {531}, year = {2003} } @article{faucris.120314524, abstract = {Practical applications of ionic liquids (ILs) often involve IL/oxide interfaces, but little is known regarding their interfacial chemistry. The unusual physicochemical properties of ILs, including their exceptionally low vapor pressure, provide access to such interfaces using a surface science approach in ultrahigh vacuum (UHV). We have applied synchrotron radiation photoelectron spectroscopy (SR-PES) to the study of a thin film of the ionic liquid [CCIm][TfN] prepared in situ in UHV on ordered stoichiometric CeO(111) and partially reduced CeO . On the partially reduced surface, we mostly observe decomposition of the anion. On the stoichiometric CeO(111) surface, however, a layer of surface-anchored organic products with high thermal stability is formed upon reaction of the cation. The suggested acid-base reaction pathway may provide well-defined functionalized IL/solid interfaces on basic oxides. &copy; 2012 American Chemical Society.}, author = {Schernich, Stefan and Laurin, Mathias and Lykhach, Yaroslava and Steinrück, Hans-Peter and Tsud, Nataliya and Skala, Tomas and Prince, Kevin C. and Taccardi, Nicola and Matolin, Vladimir and Wasserscheid, Peter and Libuda, Jörg}, doi = {10.1021/jz301856a}, faupublication = {yes}, journal = {Journal of Physical Chemistry Letters}, pages = {30-35}, peerreviewed = {Yes}, title = {{Functionalization} of oxide surfaces through reaction with 1,3-dialkylimidazolium ionic liquids}, volume = {4}, year = {2013} } @article{faucris.119801044, abstract = {A strategy to develop improved catalysts is to create systems that merge the advantages of heterogeneous and molecular catalysis. One such system involves supported liquid-phase catalysts, which feature a molecularly defined, catalytically active liquid film/droplet layer adsorbed on a porous solid support. In the past decade, this concept has also been extended to supported ionic liquid-phase catalysts. Here we develop this idea further and describe supported catalytically active liquid metal solutions (SCALMS). We report a liquid mixture of gallium and palladium deposited on porous glass that forms an active catalyst for alkane dehydrogenation that is resistant to coke formation and is thus highly stable. X-ray diffraction and X-ray photoelectron spectroscopy, supported by theoretical calculations, confirm the liquid state of the catalytic phase under the reaction conditions. Unlike traditional heterogeneous catalysts, the supported liquid metal reported here is highly dynamic and catalysis does not proceed at the surface of the metal nanoparticles, but presumably at homogeneously distributed metal atoms at the surface of a liquid metallic phas}, author = {Taccardi, Nicola and Grabau, Mathias and Debuschewitz, Jonas and Distaso, Monica and Brandl, Marco and Hock, Rainer and Maier, Florian and Papp, Christian and Erhard, Jannis and Neiß, Christian and Peukert, Wolfgang and Görling, Andreas and Steinrück, Hans-Peter and Wasserscheid, Peter}, doi = {10.1038/nchem.2822}, faupublication = {yes}, journal = {Nature chemistry}, pages = {862-867}, peerreviewed = {Yes}, title = {{Gallium}-rich {Pd}-{Ga} phases as supported liquid metal catalysts}, volume = {9}, year = {2017} } @article{faucris.255807594, abstract = {Chemoselective deoxygenation by hydrogen is particularly challenging but crucial for an efficient late-stage modification of functionality-laden fine chemicals, natural products, or pharmaceuticals and the economic upgrading of biomass-derived molecules into fuels and chemicals. We report here on a reusable earth-abundant metal catalyst that permits highly chemoselective deoxygenation using inexpensive hydrogen gas. Primary, secondary, and tertiary alcohols as well as alkyl and aryl ketones and aldehydes can be selectively deoxygenated, even when part of complex natural products, pharmaceuticals, or biomass-derived platform molecules. The catalyst tolerates many functional groups including hydrogenation-sensitive examples. It is efficient, easy to handle, and conveniently synthesized from a specific bimetallic coordination compound and commercially available charcoal. Selective, sustainable, and cost-efficient deoxygenation under industrially viable conditions seems feasible.}, author = {Schwob, T. and Kunnas, P. and De Jonge, Niels and Papp, Christian and Steinrück, Hans-Peter and Kempe, Rhett}, doi = {10.1126/sciadv.aav3680}, faupublication = {yes}, journal = {Science Advances}, note = {CRIS-Team Scopus Importer:2021-04-20}, peerreviewed = {Yes}, title = {{General} and selective deoxygenation by hydrogen using a reusable earth-abundant metal catalyst}, volume = {5}, year = {2019} } @article{faucris.107829304, abstract = {Upon exposure to Fe(CO) , the formation of pure cubic Fe nanocrystals with dimensions up to &sim;75 nm is reported on ultra-thin SiO films (thickness &asymp; 0.5 nm) on Si(001), which have been prepared in situ under UHV conditions. The active centers for initial decomposition of Fe(CO) resulting in the growth of the Fe clusters are proposed to be SiO sites. After nucleation at these sites, further crystal growth is observed due to autocatalytic dissociation of Fe(CO) at room temperature. The density of the Fe clusters can be increased by irradiating the surface with a focused electron beam (15 keV) prior to gas exposure. The formation of the active SiO sites upon electron irradiation is attributed to oxygen desorption via the Knotek-Feibelman mechanism. &copy; 2011 the Owner Societies.}, author = {Walz, Marie-Madeleine and Vollnhals, Florian and Schirmer, Michael and Steinrück, Hans-Peter and Marbach, Hubertus}, doi = {10.1039/c1cp20865a}, faupublication = {yes}, journal = {Physical Chemistry Chemical Physics}, pages = {17333-17338}, peerreviewed = {Yes}, title = {{Generation} of clean iron nanocrystals on an ultra-thin {SiO} x film on {Si}(001)}, volume = {13}, year = {2011} } @article{faucris.108284264, abstract = {We explore the electron-beam-induced deposition (EBID) of iron pentacarbonyl, Fe(CO)5, in ultrahigh vacuum (UHV) on clean and modified Rh(110) surfaces by scanning electron microscopy (SEM), scanning Auger microscopy (SAM), and local Auger electron spectroscopy (AES). In EBID a highly focused electron beam is used to locally decompose the iron pentacarbonyl precursor molecules with the goal to generate pure iron nanostructures. It is demonstrated that the selectivity of the process strongly depends on the surface properties. On a perfect, clean Rh(110) surface almost no selectivity is observed; i.e., deposition of Fe is found on irradiated and nonirradiated surface regions due to catalytic decomposition of the Fe(CO)5. However, on a structurally nonperfect Rh(110) surface and on a Tiprecovered Rh(110) surface high selectivity is found; i.e., Fe deposits are primarily formed in irradiated regions. The role of catalytic and autocatalytic growth of iron on clean Rh respective iron deposits is discussed. The purity of the Fe deposits was always very high (&gt;88%). It is demonstrated that the deposited Fe structures can be selectively oxidized to iron oxide by exposure to oxygen. Furthermore, attempts to write Fe line deposits were also successful, and line diameters smaller than 25 nm could be achieved. &copy; 2009 American Chemical Society.}, author = {Lukasczyk, Thomas and Schirmer, Michael and Steinrück, Hans-Peter and Marbach, Hubertus}, doi = {10.1021/la901612u}, faupublication = {yes}, journal = {Langmuir}, pages = {11930-11939}, peerreviewed = {Yes}, title = {{Generation} of clean iron structures by electron-beam-induced deposition and selective catalytic decomposition of iron pentacarbonyl on {Rh}(110)}, volume = {25}, year = {2009} } @article{faucris.108682684, abstract = {Strahlenverlaufsberechnungen werden heute praktisch nur noch am Computer durchgef&uuml;hrt. Dies ersetzt aufwendige Rechentechniken, und die physikalischen Ergebnisse r&uuml;cken st&auml;rker in den Vordergrund. Das Programmpaket GOPTIK, das auf unserer Homepage abrufbar ist, kombiniert Computerprogramme mit Textinformationen.}, author = {Girwidz, Raimund and Schmidt, Jörg and Steinrück, Hans-Peter}, doi = {10.1002/piuz.19990300507}, faupublication = {yes}, journal = {Physik in unserer Zeit}, note = {UnivIS-Import:2015-03-05:Pub.1999.nat.dchph.lpc2.geomet}, pages = {216-218}, peerreviewed = {No}, title = {{Geometrische} {Optik} am {Computer}}, url = {http://onlinelibrary.wiley.com/wol1/doi/10.1002/piuz.19990300507/abstract}, volume = {30}, year = {1999} } @article{faucris.120313204, abstract = {The intercalation of a graphene layer adsorbed on a metal surface by gold or other metals is a standard procedure. While it was previously shown that pristine, i.e., undoped, and nitrogen-doped graphene sheets can be decoupled from a nickel substrate by intercalation with gold atoms in order to produce quasi-free-standing graphene, we find the gold intercalation behavior for boron-doped graphene on a Ni(111) surface to be more complex: for low boron contents (2-5%) in the graphene lattice only partial gold intercalation occurs and for higher boron contents (up to 20%) no intercalation is observed. In order to understand this different behavior, a density functional theory investigation is carried out, comparing undoped as well as substitutional nitrogen- and boron-doped graphene on Ni(111). We identify the stronger binding of the boron atoms to the nickel substrate as the factor responsible for the different intercalation behavior in the case of boron doping. However, the calculations predict that this energetic effect prevents the intercalation process only for large boron concentrations and that it can be overcome for smaller boron coverages, in line with our x-ray photoelectron spectroscopy experiments. &copy; 2013 IOP Publishing Ltd.}, author = {Zhao, Wei and Gebhardt, Julian and Gotterbarm, Karin and Höfert, Oliver and Gleichweit, Christoph and Papp, Christian and Görling, Andreas and Steinrück, Hans-Peter}, doi = {10.1088/0953-8984/25/44/445002}, faupublication = {yes}, journal = {Journal of Physics: Condensed Matter}, peerreviewed = {Yes}, title = {{Gold} intercalation of boron-doped graphene on {Ni}(111): {XPS} and {DFT} study}, volume = {25}, year = {2013} } @article{faucris.107829744, abstract = {A combined high-resolution X-ray photoelectron spectroscopy (HR-XPS) and ab initio density functional theory study on graphene on Ni(111) shows the coexistence of two structures, a bridge-top and a top-fcc structure, that have almost identical energies according to DFT calculations. Consequently, both geometries are detected simultaneously on the Ni(111) surface by HR-XPS, while their relative fractions depend on minor surface defect concentrations (pinning sites). The two structures are identified due to their different core level shifts that are in line with DFT calculations. &copy; 2011 American Chemical Society.}, author = {Zhao, Wei and Kozlov, Sergey M. and Höfert, Oliver and Gotterbarm, Karin and Lorenz, Michael Peter Andreas and Vines, Francesc and Papp, Christian and Görling, Andreas and Steinrück, Hans-Peter}, doi = {10.1021/jz200043p}, faupublication = {yes}, journal = {Journal of Physical Chemistry Letters}, pages = {759-764}, peerreviewed = {Yes}, title = {{Graphene} on {Ni}(111): {Coexistence} of different surface structures}, volume = {2}, year = {2011} } @article{faucris.122523984, abstract = {The adsorption of CO on graphene-supported Pd nanoparticles was studied in situ with high-resolution synchrotron-based X-ray photoelectron spectroscopy. At 150 K, CO adsorbs mainly in bridge and 3-fold-hollow sites. The nanoparticles are considered as a mixture of low-index facets. The variation of the amount of deposited Pd revealed identical CO adsorption behavior for all investigated cases, confirming a similar average cluster size over a wide range of Pd coverages. The desorption characteristics were studied with temperature-programmed XPS. The observed desorption maxima at 230 and 430 K are in good agreement with temperature-programmed desorption data on stepped Pd single crystals. At 500 K, CO is completely desorbed from the Pd clusters. The adsorption and desorption of CO are found to be not fully reversible as the Pd particles undergo restructuring upon heating.}, author = {Gotterbarm, Karin and Bronnbauer, Carina and Bauer, Udo and Papp, Christian and Steinrück, Hans-Peter}, doi = {10.1021/jp508454h}, faupublication = {yes}, journal = {Journal of Physical Chemistry C}, pages = {25097-25103}, peerreviewed = {Yes}, title = {{Graphene}-{Supported} {Pd} {Nanoclusters} {Probed} by {Carbon} {Monoxide} {Adsorption}}, volume = {118}, year = {2014} } @article{faucris.107303284, abstract = {Graphene grown on Rh(111) was used as a template for the growth of Pd nanoclusters. Using high-resolution synchrotron radiation-based X-ray photoelectron spectroscopy, we studied the deposition of Pd on corrugated graphene in situ. From the XP spectra, we deduce a cluster-by-cluster growth mode. The formation of clusters with 3 nm diameter was confirmed by low-temperature scanning tunneling microscopy measurements. The investigation of the thermal stability of the Pd particles showed three characteristic temperature regimes: Up to 550 K restructuring of the particles takes place, between 550 and 750 K the clusters coalesce into larger agglomerates, and finally between 750 and 900 K Pd intercalates between the graphene layer and the Rh surface.}, author = {Gotterbarm, Karin and Steiner, Christian and Bronnbauer, Carina and Bauer, Udo and Steinrück, Hans-Peter and Maier, Sabine and Papp, Christian}, doi = {10.1021/jp5052563}, faupublication = {yes}, journal = {Journal of Physical Chemistry C}, pages = {15934--15939}, peerreviewed = {Yes}, title = {{Graphene}-{Templated} {Growth} of {Pd} {Nanoclusters}}, volume = {118}, year = {2014} } @article{faucris.108349604, abstract = {The growth and the electronic structure of thin Zn layers on Cu(111) in the coverage range 0 &le; &Theta; &le; 60 ML was studied by temperature-programmed desorption (TPD) of Zn and CO and angle resolved UV-photoelectron spectroscopy (ARUPS). CO titration experiments indicate two-dimensional growth for small amounts of Zn (up to 1 ML) after annealing to 400 K. Upon further annealing, the first Zn layer desorbs over a relatively wide temperature range between 500 and 640 K. For sub-monolayers of Zn an irreversible phase transition is found around 475 K which causes drastic changes in the shape of the CO-TPD spectra from these surfaces. The ARUPS data show a small but clear dispersion of the Zn 3d states for Zn layers above 0.5 ML. The transition at 475 K causes a narrowing of the Zn 3d bandwidth leaving the average binding energy unchanged. This indicates a larger separation of the Zn atoms in this surface arrangement which can be explained by a substitutional adsorption of Zn atoms. &copy; 2001 Elsevier Science B.V. All rights reserved.}, author = {Ammon, Christian and Held, Georg and Pantförder, Jörg and Steinrück, Hans-Peter}, doi = {10.1016/S0039-6028(00)01083-9}, faupublication = {yes}, journal = {Surface Science}, pages = {886-890}, peerreviewed = {Yes}, title = {{Growth} and electronic properties of thin {Zn} layers on {Cu}(1 1 1)}, year = {2001} } @article{faucris.119072844, abstract = {The doping of graphene to tune its electronic properties is essential for its further use in carbon-based electronics. Adapting strategies from classical silicon-based semiconductor technology, we use the incorporation of heteroatoms in the 2D graphene network as a straightforward way to achieve this goal. Here, we report on the synthesis of boron-doped graphene on Ni(111) in a chemical vapor deposition process of triethylborane on the one hand and by segregation of boron from the bulk of the substrate crystal on the other hand. The chemical environment of boron was determined by x-ray photoelectron spectroscopy, and angle-resolved photoelectron spectroscopy was used to analyze the impact on the band structure. Doping with boron leads to a shift of the graphene bands to lower binding energies. The shift depends on the doping concentration and for a doping level of 0.3 ML a shift of up to 1.2 eV is observed. The experimental results are in agreement with density-functional calculations. Furthermore, our calculations suggest that doping with boron leads to graphene preferentially adsorbed in the top-fcc geometry, since the boron atoms in the graphene lattice are then adsorbed at substrate fcc-hollow sites. The smaller distance of boron atoms incorporated into graphene compared to graphene carbon atoms leads to a bending of the doped graphene sheet in the vicinity of the boron atoms. By comparing calculations of doped and undoped graphene on Ni(111), as well as the respective freestanding cases, we are able to distinguish between the effects that doping and adsorption have on the band structure of graphene. Both doping and bonding to the surface result in opposing shifts on the graphene bands. &copy; 2013 American Physical Society.}, author = {Gebhardt, Julian and Koch, Roland and Zhao, Wei and Höfert, Oliver and Gotterbarm, Karin and Mammadov, Samir and Papp, Christian and Görling, Andreas and Steinrück, Hans-Peter and Seyller, Thomas}, doi = {10.1103/PhysRevB.87.155437}, faupublication = {yes}, journal = {Physical Review B}, peerreviewed = {Yes}, title = {{Growth} and electronic structure of boron-doped graphene}, volume = {87}, year = {2013} } @article{faucris.121299024, abstract = {We report on experimental and theoretical investigations of nitrogen-doped graphene. The incorporation of nitrogen was achieved during chemical-vapor deposition on Ni(111) using pyridine as a precursor. The obtained graphene layers were investigated using photoelectron spectroscopy. By studying C 1s and N 1s core levels, we show that the nitrogen content is influenced by the growth temperature and determine the atomic arrangement of the nitrogen atoms. Valence-band photoelectron spectra show that the incorporation of nitrogen leads to a broadening of the photoemission lines and a shift of the &pi; band. Density functional calculations for two possible geometric arrangements, the substitution of carbon atoms by nitrogen and vacancies in the graphene sheet with pyridinic nitrogen at the edges, reveal that the two arrangements have opposite effects on the band structure. For the present experimental approach, vacancies with pyridinic nitrogen are dominant. In the latter case the vacancies generated by the nitrogen doping, not the nitrogen itself, have the main effect on the band structure. By intercalating gold between the doped graphene layer and the Ni(111) substrate electronic decoupling is achieved. After intercalation the doping remains. &copy; 2012 American Physical Society.}, author = {Koch, Roland and Weser, M. and Zhao, Wei and Vines, Francesc and Gotterbarm, Karin and Kozlov, Sergey M. and Höfert, Oliver and Ostler, Markus and Papp, Christian and Gebhardt, Julian and Steinrück, Hans-Peter and Görling, Andreas and Seyller, Thomas}, doi = {10.1103/PhysRevB.86.075401}, faupublication = {yes}, journal = {Physical Review B}, peerreviewed = {Yes}, title = {{Growth} and electronic structure of nitrogen-doped graphene on {Ni}(111)}, volume = {86}, year = {2012} } @article{faucris.107802464, abstract = {The growth and oxidation of graphene supported on Rh(111) was studied in situ by high-resolution X-ray photoelectron spectroscopy. By variation of propene pressure and surface temperature the optimum growth conditions were identified, yielding graphene with low defect density. Oxidation of graphene was studied at temperatures between 600 and 1000 K, at an oxygen pressure of &sim;2 &times; 10 mbar. The oxidation follows sigmoidal reaction kinetics. In the beginning, the reaction rate is limited by the number of defects, which represent the active sites for oxygen dissociation. After an induction period, the reaction rate increases and graphene is rapidly removed from the surface by oxidation. For graphene with a high defect density we found that the oxidation is faster. In general, a reduction of the induction period and a faster oxidation occur at higher temperatures. &copy; 2013 The Owner Societies.}, author = {Gotterbarm, Karin and Zhao, Wei and Höfert, Oliver and Gleichweit, Christoph and Papp, Christian and Steinrück, Hans-Peter}, doi = {10.1039/c3cp53802h}, faupublication = {yes}, journal = {Physical Chemistry Chemical Physics}, pages = {19625-19631}, peerreviewed = {Yes}, title = {{Growth} and oxidation of graphene on {Rh}(111)}, volume = {15}, year = {2013} } @article{faucris.227766928, abstract = {The h-BN nanomesh on Rh(111) is used as eggbox-like template for the formation of arrays of Pt nanoclusters with a narrow size distribution. Nanoclusters with sizes from 1 up to 50 atoms are prepared simultaneously in a wedge-like structure by depositing a coverage gradient on the h-BN nanomesh, and thus can be investigated under identical conditions. We studied the preparation and properties of these Pt nanoclusters of different size in situ by high-resolution X-ray photoelectron spectroscopy and scanning tunneling microscopy. For a Pt coverage of 0.1 ML, all pores of the h-BN nanomesh are filled with nanoclusters with a remarkably uniform cluster size of ≈12 Pt atoms per pore, and high stability up to 400 K. Above 0.2 ML Pt, the clusters are less stable. The coverage dependent analysis shows that for Pt coverages below 0.1 ML, the number of nanoclusters is smaller - and the number of empty pores higher - than expected for a simple hit and stick mechanism. We assign this behavior to an initially higher mobility of the Pt atoms in a hot precursor state.}, author = {Düll, Fabian and Meusel, Manuel and Späth, Florian and Schötz, Simon and Bauer, Udo and Bachmann, Philipp and Steinhauer, Johann and Steinrück, Hans-Peter and Bayer, Andreas and Papp, Christian}, doi = {10.1039/c9cp04095a}, faupublication = {yes}, journal = {Physical Chemistry Chemical Physics}, note = {CRIS-Team Scopus Importer:2019-10-11}, pages = {21287-21295}, peerreviewed = {Yes}, title = {{Growth} and stability of {Pt} nanoclusters from 1 to 50 atoms on h-{BN}/{Rh}(111)}, volume = {21}, year = {2019} } @article{faucris.245882362, abstract = {Understanding the growth of ultrathin films of ionic liquids (ILs) on metal surfaces is of highest relevance for a variety of applications. We present a detailed study of the growth of the wetting layer and successive multilayers of 1,3-dimethylimidazolium bis[(trifluoromethyl)sulfonyl]imide ([C1C1Im][Tf2N]) on Au(111). By atomic force microscopy (AFM) in ultrahigh vacuum, we follow the temperature-dependent behavior between 110 and 300 K at defined coverages. We initially observe the formation of a wetting layer with a thickness of ∼0.37 nm with anions and cations arranged in a checkerboard structure. Stable AFM imaging up to 280 K allows us to follow the IL growing on top of the wetting layer in bilayers with an average thickness of ∼0.71 nm, that is, double the height of the wetting layer, in a bilayer-by-bilayer fashion. This growth behavior is independently confirmed from the surface morphology, as deduced from AFM and angle-resolved X-ray photoelectron spectroscopy. High-resolution AFM images at 110 K allow for identifying the molecular surface structure of the bilayers as a striped phase, which is one of the phases also seen for the wetting layer (Meusel, M.; Lexow, M.; Gezmis, A.; Schotz, S.; Wagner, M.; Bayer, A.; Maier, F.; Steinrück, H. P. Atomic Force and Scanning Tunneling Microscopy of Ordered Ionic Liquid Wetting Layers from 110 K up to Room Temperature. ACS Nano2020, 14, 9000-9010).}, author = {Meusel, Manuel and Lexow, Matthias and Gezmis, Emine and Bayer, Andreas and Maier, Florian and Steinrück, Hans-Peter}, doi = {10.1021/acs.langmuir.0c02596}, faupublication = {yes}, journal = {Langmuir}, note = {CRIS-Team Scopus Importer:2020-11-27}, pages = {13670-13681}, peerreviewed = {Yes}, title = {{Growth} of {Multilayers} of {Ionic} {Liquids} on {Au}(111) {Investigated} by {Atomic} {Force} {Microscopy} in {Ultrahigh} {Vacuum}}, volume = {36}, year = {2020} } @article{faucris.108439144, abstract = {Detailed knowledge of the structure and degree of oxidation of platinum surfaces under operando conditions is essential for understanding catalytic performance. However, experimental investigations of platinum surface oxides have been hampered by technical limitations, preventing in situ investigations at relevant pressures. As a result, the time-dependent evolution of oxide formation has only received superficial treatment. In addition, the amorphous structures of many surface oxides have hindered realistic theoretical studies. Using near-ambient pressure X-ray photoelectron spectroscopy (NAP-XPS) we show that a time scale of hours (t&ge;4 h) is required for the formation of platinum surface oxides. These experimental observations are consistent with ReaxFF grand canonical Monte Carlo (ReaxFF-GCMC) calculations, predicting the structures and coverages of stable, amorphous surface oxides at temperatures between 430&ndash;680 K and an O partial pressure of 1 mbar.}, author = {Fantauzzi, Donato and Krick Calderon, Sandra and Mueller, Jonathan E. and Grabau, Mathias and Papp, Christian and Steinrück, Hans-Peter and Senftle, Thomas P. and van Duin, Adri C. T. and Jacob, Timo}, doi = {10.1002/anie.201609317}, faupublication = {yes}, journal = {Angewandte Chemie-International Edition}, keywords = {interfaces; kinetics; oxidation; phase transitions; surface chemistry}, month = {Jan}, pages = {2594-2598}, peerreviewed = {Yes}, title = {{Growth} of {Stable} {Surface} {Oxides} on {Pt}(111) at {Near}-{Ambient} {Pressures}}, url = {http://onlinelibrary.wiley.com/wol1/doi/10.1002/anie.201609317/abstract}, volume = {56}, year = {2017} } @article{faucris.108504264, abstract = {Using X-ray photoelectron spectroscopy (XPS) and temperature programmed desorption (TPD) we studied the properties of thin Cr films in the nominal coverage range between 0.13 and 4 monolayers (ML), which were evaporated onto a Ni(111) surface pre-covered with up to 14 ML benzene. Evaporation of small amounts of Cr (&lt; 0.5 ML) onto thick benzene layers (&gt; 4 ML) at 100 K leads to the formation of non-metallic bis(benzene)chromium (Cr(CH)) rather than condensation of small clusters in the benzene matrix, as can be seen from the positions and shapes of the Cr 2p peaks in XPS. Upon annealing to 400 K these films transform into metallic Cr as is indicated by a Cr 2p peak shift of -0.8 eV, and significant changes in the peak shapes. For 0.5-2 ML a metallic Cr species, in addition to the non-metallic species, is already seen at 100 K. For higher coverages &gt; 2 ML only the metallic species is seen in XPS and the Cr 2p peak shape does then not change upon annealing. The development of the C 1s spectra upon annealing reveals that there is a significant amount of benzene buried under the Cr layer, which is partially dissociated, depending on the annealing temperature and the Cr coverage.}, author = {Sklarek, Werner and Held, Georg and Ammon, Christian and Steinrück, Hans-Peter}, doi = {10.1016/S0169-4332(98)00737-5}, faupublication = {yes}, journal = {Applied Surface Science}, pages = {327-331}, peerreviewed = {Yes}, title = {{Growth} of ultrathin {Cr} films on benzene-covered {Ni}(111)}, volume = {142}, year = {1999} } @article{faucris.322281198, abstract = {Borazine is a well-established precursor molecule for the growth of hexagonal boron nitride (h-BN) via chemical vapor deposition on metal substrates. To understand the formation of the h-BN/Rh(111) moiré from borazine on a molecular level, we investigated the low-temperature adsorption and thermally induced on-surface reaction of borazine on Rh(111) in situ using synchrotron radiation-based high-resolution x-ray photoelectron spectroscopy (XPS), temperature-programmed XPS, and near-edge x-ray absorption fine structure measurements. We find that borazine adsorbs mainly as an intact molecule and have identified a flat-lying adsorption geometry. Borazine multilayers are observed to desorb below 200 K. Starting at about 300 K, dehydrogenation of the remaining borazine and borazine fragments takes place, and disordered boron nitride starts to grow. Above 600 K, the formation of the h-BN sets in. Finally, at 1100 K, the conversion to h-BN is complete. The h-BN formed by deposition and post-annealing was compared to the h-BN grown by an established procedure, proving the successful preparation of the desired two-dimensional material.}, author = {Freiberger, Eva Marie and Düll, Fabian and Bachmann, Phiona and Steinhauer, Johann and Williams, Federico J. and Steinrück, Hans-Peter and Papp, Christian}, doi = {10.1063/5.0202431}, faupublication = {yes}, journal = {Journal of Chemical Physics}, note = {CRIS-Team Scopus Importer:2024-05-10}, peerreviewed = {Yes}, title = {h-{BN} in the making: {The} surface chemistry of borazine on {Rh}(111)}, volume = {160}, year = {2024} } @article{faucris.108296804, abstract = {A novel class of heterogeneous gold catalysts supported on zeolite beta-NH was prepared by the deposition-precipitation method. This new class of catalyst showed interesting catalytic activities for the intramolecular cycloisomerization of &gamma;-acetylenic carboxylic acids leading to functionalized &gamma;-alkylidene &gamma;-butyrolactones. Analysis of the supported gold species with in situ X-ray photoelectron spectroscopy (in situ XPS) suggests that cationic Au (possibly Au) can play an important role in such reactions. The high discrepancy in catalyst stability in favor of the Au supported on the zeolite system over bulk AuO is explained by 1) the size of the particles and 2) the reversibility of the redox deactivating process (Au&rarr;Au ) in the presence of oxygen for the supported system. The efficiency of this system allowed reaction under mild heterogeneous conditions. The potential for catalyst recycling was also highlighted. &copy; 2008 Wiley-VCH Verlag GmbH &amp; Co. KGaA.}, author = {Neatu, Florentina and Li, Zhi and Richards, Ryan and Toullec, Patrick Y. and Genet, Jean-Pierre and Dumbuya, Karifala and Gottfried, Michael and Steinrück, Hans-Peter and Parvulescu, Vasile I. and Michelet, Veronique}, doi = {10.1002/chem.200801327}, faupublication = {yes}, journal = {Chemistry - A European Journal}, pages = {9412-9418}, peerreviewed = {Yes}, title = {{Heterogeneous} gold catalysts for efficient access to functionalized lactones}, volume = {14}, year = {2008} } @article{faucris.113113044, abstract = {Well dispersed and homogeneously distributed Pd nanoparticles within a silica matrix were synthesized by a two stage process: (1) intercalation of palladium tetrammine ions into the layered aluminium-free silicate Na ilerite followed by (2) a self-reduction of the complex through decomposition of the tetrammine ligands by calcination at 550&deg;C for 5h under N or air. Samples calcined in N predominantly contained nanoparticles of metallic Pd, while calcination in air led largely to the formation of PdO, as confirmed by XPS and supported by XRD and TGA. Thus, the Pd/PdO loading in the silica can be selectively tuned through this method. The intercalates were characterized by standard methods such as XRD, TGA, ICP and TEM. TGA of the intercalates indicated that the stabilization of the palladium tetrammine complex was enhanced by intercalation into Na ilerite. Based on ICP analysis, the Pd loadings in the intercalates were estimated to be about 18mass-%, which was also in agreement with the results from TGA. TEM revealed that the Pd/PdO nanoparticles were well dispersed in the silica matrix with an average particle size of approximately 8-10nm after calcination in air. &copy; 2010 Elsevier B.V.}, author = {Ofili, Ifeanyi Jimmy and Steinrück, Hans-Peter and Schwieger, Wilhelm and Ramakrishnan, Ayyappan and Dumbuya, K. and Gottfried, Michael}, doi = {10.1016/j.clay.2010.10.014}, faupublication = {yes}, journal = {Applied Clay Science}, pages = {8-14}, peerreviewed = {Yes}, title = {{Highly} dispersed {Pd} nanoparticles within silica: {Synthesis} and characterization}, volume = {51}, year = {2011} } @article{faucris.228037005, abstract = {Our contribution demonstrates that rhodium, an element that has barely been reported as an active metal for selective dehydrogenation of alkanes becomes a very active, selective, and robust dehydrogenation catalyst when exposed to propane in the form of single atoms at the interface of a solid-supported, highly dynamic liquid Ga-Rh mixture. We demonstrate that the transition to a fully liquid supported alloy droplet at Ga/Rh ratios above 80, results in a drastic increase in catalyst activity with high propylene selectivity. The combining results from catalytic studies, X-ray photoelectron spectroscopy, IR-spectroscopy under reaction conditions, microscopy, and density-functional theory calculations, we obtained a comprehensive microscopy picture of the working principle of the Ga-Rh supported catalytically active liquid metal solution.}, author = {Raman, Narayanan and Maisel, Sven and Grabau, Mathias and Taccardi, Nicola and Debuschewitz, Jonas and Wolf, Moritz and Wittkämper, Haiko and Bauer, Tanja and Wu, Mingjian and Haumann, Marco and Papp, Christian and Görling, Andreas and Spiecker, Erdmann and Libuda, Jörg and Steinrück, Hans-Peter and Wasserscheid, Peter}, doi = {10.1021/acscatal.9b02459}, faupublication = {yes}, journal = {ACS Catalysis}, keywords = {alkane; alkene; catalysis; dehydrogenation; gallium; rhodium}, note = {CRIS-Team Scopus Importer:2019-10-18}, pages = {9499-9507}, peerreviewed = {Yes}, title = {{Highly} {Effective} {Propane} {Dehydrogenation} {Using} {Ga}-{Rh} {Supported} {Catalytically} {Active} {Liquid} {Metal} {Solutions}}, year = {2019} } @article{faucris.113321164, abstract = {Synchrotron radiation has been used to investigate the energy, polarization and angular dependences of the O KLL Auger yield and the H/D ion yield from multilayers and monolayers of HO and DO on Ru(001) in the O 1s region. A sharp, narrow peak in the ion yield, directed along the surface normal, has been found at about 534 eV for all layers. Its counterpart in the Auger yield, which is representative of the absorption cross section, is comparatively weak. We assign this peak to the 1a &rarr; 4a core-to-bound transition. In this case, dissociation and core-hole decay appear to proceed on roughly the same time scale. &copy; 1988.}, author = {Coulman, D. and Puschmann, A. and Wurth, W. and Steinrück, Hans-Peter and Menzel, Dietrich}, doi = {10.1016/0009-2614(88)87190-2}, faupublication = {no}, journal = {Chemical Physics Letters}, pages = {371-376}, peerreviewed = {Yes}, title = {{Highly} efficient dissociation of condensed and adsorbed water via core-to-bound excitation}, volume = {148}, year = {1988} } @article{faucris.108476764, abstract = {Angular distributions of Pt4f 7 2 and 4f 5 2 photoelectrons were measured for the reconstructed Pt(110)l &times; 2 surface at six different kinetic energies ranging from 120 up to 370 eV, using an angle-multichannel electron analyzer. From the photoelectron diffraction patterns, holographic reconstructions were performed using (1) the single wave number reconstruction method and (2) the multiple wave number phased sum method. The results obtained from the two photoemission lines are overall very similar. For the single energy reconstruction, the quality of the reconstructed images strongly depends on the kinetic energy of the photoelectrons: at high kinetic energies (370 eV) the reconstructed images are dominated by the maxima attributed to the nearest neighbors in the plane above the emitter; at low kinetic energies (120 eV) artifacts dominate. The multiple wave number algorithm leads to strong twin-image suppression, a reduction of certain artifacts but no noticeable improvement of resolution. While the overall quality of the reconstructed images increases when using the multiple energy algorithm, the best quality is observed for the single energy reconstruction for a kinetic energy of ~ 370 eV. In all cases the atomic positions are shifted from their true values by 0.2-0.3 &Aring; due to the phase shift in the scattering process. &copy; 1994.}, author = {Steinrück, Hans-Peter and et al.}, author_hint = {Zharnikov M., Mehl D., Weinelt M., Zebisch P., Steinrück H.-P.}, faupublication = {no}, journal = {Surface Science}, pages = {82-96}, peerreviewed = {Yes}, support_note = {Author relations incomplete. You may find additional data in field 'author{\_}hint'}, title = {{Holographic} reconstruction of {Pt}(110) using multiple wave number photoelectron diffraction patterns}, url = {https://www.scopus.com/record/display.uri?eid=2-s2.0-0028445065&origin=inward}, volume = {312}, year = {1994} } @article{faucris.108477644, abstract = {Angular distributions of Ni 3p photoelectrons for clean Ni(111) and of S 2p photoelectrons for the p(2 &times; 2)S and (5&radic;3 &times; 2)S structures on Ni(111) were measured at seven different kinetic energies ranging from 239 to 417 eV for Ni 3p and from 130 to 322.5 eV for S 2p. From the photoelectron diffraction patterns, holographic reconstructions were performed using (1) the single wave number reconstruction method and (2) the multiple wave number phased sum method. For the clean surface, neighboring atoms in the plane of the emitter and some atoms in the second and third plane above the emitter can be identified; the holographic reconstruction in the first plane above the emitter is however dominated by intense artifacts. For Ni(111)-p(2 &times; 2)S, the three-fold hollow fcc adsorption site of sulphur can be unequivocally identified with a distance to the first Ni layer of about 1.6 &Aring;. Holographic reconstructions for Ni(111)-(5&radic;3 &times; 2)S allow to exclude the three-fold hollow position of sulphur and disagree with a proposed mixing of different non-symmetric adsorption sites. The distance of the sulphur atoms from the top Ni layer is determined to 1.1-1.2 &Aring;. The reconstructions are consistent with a quasi-(100) reconstruction of the Ni(111) crystal surface. For all systems the potential of using only an azimuthal sector instead of the full hemispherical holograms for the reconstruction is discussed. &copy; 1995.}, author = {Zharnikov, M. and Weinelt, M. and Zebisch, P. and Stichler, M. and Steinrück, Hans-Peter}, doi = {10.1016/0039-6028(95)00465-3}, faupublication = {no}, journal = {Surface Science}, pages = {114-134}, peerreviewed = {Yes}, title = {{Holography} of clean and sulphur-covered {Ni}(111) using multiple wave number photoelectron diffraction patterns}, volume = {334}, year = {1995} } @article{faucris.108352024, abstract = {This article reviews the work performed by the authors regarding photoelectron holography on clean metal surfaces and simple adsorbate arrangements. The following systems were investigated: Pt(1 1 0)-1 &times; 2, Ni(1 1 0), Ni(1 1 1), Ni(1 1 0)-c(2 &times; 2) S, Ni(1 1 1)-p(2 &times; 2) S and Ni(1 1 1)-(5&radic;3 &times; 2) S. The photoelectron diffraction patterns, which are interpreted as holograms, were recorded using synchrotron radiation at the German synchrotron facility BESSY-I in Berlin. For most systems these holograms were acquired at various kinetic energies. The real space structures were reconstructed from these data using the single wave number as well as the multiple wave number algorithm, without any prior assumptions. It was demonstrated that the local geometrical structure of clean single crystal surfaces and of adsorbate systems can be successfully reconstructed by using photoelectron holography with some restrictions.}, author = {Steinrück, Hans-Peter and Zharnikov, Michael}, doi = {10.1088/0953-8984/13/47/302}, faupublication = {yes}, journal = {Journal of Physics: Condensed Matter}, pages = {10533-10560}, peerreviewed = {Yes}, title = {{Holography} with photoelectrons: {A} direct approach}, volume = {13}, year = {2001} } @article{faucris.122564244, abstract = {We have studied the adsorption and self-metalation of tetraphenylporphyrin (2HTPP) on TiO2(110) -1 x 1 with X-ray Photoelectron Spectroscopy (XPS) and Scanning Tunneling Microscopy (STM). Upon adsorption at room temperature the first monolayer of 2HTPP is protonated by protons from the surface, forming porphyrin diacid (4HTPP(2+)). In STM, single molecules with low mobility and no long-range order were observed. As the surface is heated to 400 K, any unprotonated 2HTPP molecules in the second layer metalate, forming titanyl tetraphenylporphyrin (TiOTPP), but the protonated molecules in the first layer remain. As the surface is heated further to 550 K even the protonated 4HTPP(2+) molecules metalate and only TiOTPP remain on the surface.}, author = {Köbl, Julia and Wang, Tao and Wang, Cici and Drost, Martin and TU, Fan and Xu, Qian and Ju, Huanxin and Wechsler, Daniel and Franke, Matthias and Pan, Haibin and Marbach, Hubertus and Steinrück, Hans-Peter and Zhu, Junfa and Lytken, Ole}, doi = {10.1002/slct.201601398}, faupublication = {yes}, journal = {ChemistrySelect}, keywords = {Adsorption;Porphyrinoids;Oxide Surfaces;Surface Chemistry;Titania}, pages = {6103-6105}, peerreviewed = {unknown}, title = {{Hungry} {Porphyrins}: {Protonation} and {Self}-{Metalation} of {Tetraphenylporphyrin} on {TiO2}(110)-1 x 1}, volume = {1}, year = {2016} } @article{faucris.107300864, abstract = {We studied the hydrogenation and dehydrogenation of nitrogen-doped graphene (NDG) by in situ high-resolution X-ray photoelectron spectroscopy (XPS) and temperature-programmed XPS (TPXPS). Nitrogen-doped graphene was prepared by low energy nitrogen implantation in pristine graphene on Ni(111). Hydrogenation of NDG was performed by exposure to atomic hydrogen. Upon hydrogenation the XP spectra in the C 1s region reveal one new peak, shifted to lower binding energies as compared to graphene, which is associated with newly formed CH groups. In the N 1s region two ne wpeaks, shifted to higher binding energies are observed; these are associated with hydrogenated pyridinic and graphitic nitrogen. TPXPS spectra reveal a different thermal stability of the two hydrogenated nitrogen species,while the C&ndash;H groups of graphene show no significant changes compared to undoped hydrogenated graphene.}, author = {Späth, Florian and Zhao, Wei and Gleichweit, Christoph and Gotterbarm, K. and Bauer, Udo and Höfert, Oliver and Steinrück, Hans-Peter and Papp, Christian}, doi = {10.1016/j.susc.2014.11.009}, faupublication = {yes}, journal = {Surface Science}, pages = {89--94}, peerreviewed = {Yes}, title = {{Hydrogenation} and dehydrogenation of nitrogen-doped graphene investigated by {X}-ray photoelectron spectroscopy}, volume = {634}, year = {2015} } @article{faucris.119845924, abstract = {We investigate the reactivity of hexagonal boron nitride (h-BN) on a Ni(1 1 1) single crystal towards atomic hydrogen over a wide exposure range. Near edge x-ray absorption fine structure and x-ray photoelectron spectroscopy (XPS) show that for low hydrogen exposures hydrogenation of the h-BN sheet is found. In contrast, intercalation of hydrogen between h-BN and the Ni(1 1 1) substrate occurs for high exposures. For intermediate regimes, a mixture of intercalation and hydrogenation is observed. From temperature-programmed desorption and temperature-programmed XPS experiments, we conclude that the hydrogen covalently bound to h-BN is rather stable with a desorption temperature of 600 K, while intercalated hydrogen is desorbing already at 390 K. Further insight into the structural arrangements and the thermodynamics of the system is obtained by comparing our experimental results with extensive density-functional theory calculations. Together with ultraviolet photoelectron spectroscopy measurements, the calculations provide detailed insight into the influence of hydrogenation on the electronic structure of h-BN.}, author = {Späth, Florian and Gebhardt, Julian and Düll, Fabian and Bauer, Udo and Bachmann, Philipp and Gleichweit, Christoph and Görling, Andreas and Steinrück, Hans-Peter and Papp, Christian}, doi = {10.1088/2053-1583/aa7d6b}, faupublication = {yes}, journal = {2D Materials}, keywords = {hexagonal boron nitride;hydrogenation;intercalation;electronic structure}, peerreviewed = {Yes}, title = {{Hydrogenation} and hydrogen intercalation of hexagonal boron nitride on {Ni}(111): reactivity and electronic structure}, volume = {4}, year = {2017} } @article{faucris.326596473, abstract = {The use of homogeneous catalysts dissolved in ionic liquids (ILs) is an established field of research. Thin IL films containing dissolved catalyst complexes can be immobilized on solid porous supports, thereby creating a heterogenized catalyst material. Aiming at the deliberate positioning of such supported ionic liquid phase (SILP) catalyst, we carried out investigations of two very similar Pt-complexes: depending on the ligand periphery, the first one is homogeneously dissolved in the IL while the second one strongly enriches at the gas/IL interface. To study these different locations within thick IL films of approximately 1 mm thickness, we investigated the hydrogenation of ethene in a continuous pool-reactor setup. The two complexes dissolved in the IL [C4C1Im][PF6] showed different activity which can be attributed to their different locations. At 313 K and 0.62 MPa total pressure, the surface-enriched complex was approximately two times more active. However, under these conditions the formation of Pt particles could be observed, with the surface-enriched complex exhibiting a stronger tendency for particle formation compared to the one homogeneously distributed in the IL, as derived from XPS and light-scattering measurements.}, author = {Khan Antara, Sharmin and Hemmeter, Daniel and Zhai, Ziwen and Kremitzl, Daniel and Maier, Florian and Koller, Thomas Manfred and Steinrück, Hans-Peter and Haumann, Marco}, doi = {10.1002/cctc.202400574}, faupublication = {yes}, journal = {ChemCatChem}, keywords = {ethene; Hydrogenation; interface enrichment; ionic liquid; light-scattering; platinum; XPS}, note = {CRIS-Team Scopus Importer:2024-08-02}, peerreviewed = {Yes}, title = {{Hydrogenation} with {Dissolved} {Pt}-{Complexes} {Homogenously} {Distributed} in the {Ionic} {Liquid} or {Enriched} at the {Gas}/{Ionic} {Liquid} {Interface}}, volume = {16}, year = {2024} } @article{faucris.123259884, author = {Papp, Christian and Wasserscheid, Peter and Libuda, Jörg and Steinrück, Hans-Peter}, faupublication = {yes}, journal = {Nachrichten aus der Chemie}, peerreviewed = {Yes}, title = {{Hydrogen}, chemically stored}, url = {https://www.scopus.com/inward/record.url?partnerID=HzOxMe3b&amp;scp=84908231404&amp;origin=inward}, volume = {62}, year = {2014} } @article{faucris.202402403, abstract = {Using a concerted effort from both experiment and theory, we determine the thermal decomposition mechanism for guaiacol on Pt(111), a reaction of interest in the area of bio-oil upgrading. This work serves as a demonstration of the power of combining in situ temperature-programmed X-ray photoelectron spectroscopy cos (TPXPS) and density functional theory (DFT) to elucidate complex reaction mechanisms occurring on heterogeneous surfaces. At low temperature (230 K), guaiacol was found to chemisorb with the aromatic ring parallel to the Pt(111) surface with five distinct carbon species and three oxygen species. As the temperature was increased, TPXPS showed several significant changes to the surface species. The increase in the species associated with the decomposition of the functional groups of guaiacol is followed by their subsequent disappearance and an increase in the nonaromatic carbon signal. On the basis of an energetic analysis of the various mechanisms using DFT, along with the comparison of the experimentally and theoretically derived core-level binding energies, we determined that guaiacol's decomposition mechanism occurs via the dehydrogenation of both the methyl and hydroxyl functional groups, followed by demethylation of the CH2 or CH group to form 1,2-benzoquinone. Further heating to above 375 K likely breaks the aromatic ring and results in the rapid formation and desorption of CO, accounting for the disappearance of the 0 is signal above 450 K These results show that a knowledgeable application of TPXPS and DFT can result in the quantitative identification of surface species during complex reactions, providing insight useful for the design of future heterogeneous surfaces.}, author = {Hensley, Alyssa J. R. and Woeckel, Claudia and Gleichweit, Christoph and Gotterbarm, Karin and Papp, Christian and Steinrück, Hans-Peter and Wang, Yong and Denecke, Reinhard and Mcewen, Jean-Sabin}, doi = {10.1021/acs.jpcc.7b10006}, faupublication = {yes}, journal = {Journal of Physical Chemistry C}, pages = {4261-4273}, peerreviewed = {Yes}, title = {{Identifying} the {Thermal} {Decomposition} {Mechanism} of {Guaiacol} on {Pt}(111): {An} {Integrated} {X}-ray {Photoelectron} {Spectroscopy} and {Density} {Functional} {Theory} {Study}}, volume = {122}, year = {2018} } @article{faucris.213380829, abstract = {We present colloidally stable and highly luminescent ZnxCd1$-$xS:Mn/ZnS core--shell nanocrystals (NCs) synthesized via a simple non-injection one-pot, two-step synthetic route, which can be easily upscaled. A systematic variation of the reaction component, parameters and thickness of the ZnS shell yielded doped nanocrystals with a very high photoluminescence quantum yield (\textgreekFpl) of 70%, which is the highest value yet reported for these Mn-doped sulfide-semiconductor NCs. These materials can be synthesized with high reproducibility in large quantities of the same high quality, i.e., the same \textgreekFpl using accordingly optimized reaction conditions. The application of these zero-reabsorption high quality NCs in the light conversion layers, deposited on top of a commercial monocrystalline silicon (mono-Si) solar cell, led to a significant enhancement of the external quantum efficiency (EQE) of this device in the ultraviolet spectral region between 300 and 400 nm up to ca. 12%. EQE enhancement is reflected by an increase in the power conversion efficiency (PCE) by nearly 0.5 percentage points and approached the theoretical limit (0.6%) expected from down-shifting for this Si solar cell. The resulting PCE may result in a BoM (bill of materials) cost reduction of app. 3% for mono-Si photovoltaic modules. Such small but distinct improvements are expected to pave the road for an industrial application of doped semiconductor NCs as cost-effective light converters for silicon photovoltaic (PV) and other optoelectronic applications.}, author = {Levchuk, Ievgen and Wuerth, C. and Krause, F. and Osvet, Andres and Batentschuk, Miroslaw and Resch-Genger, Ute and Kolbeck, Claudia and Herre, Patrick and Steinrück, Hans-Peter and Peukert, Wolfgang and Brabec, Christoph}, doi = {10.1039/C5EE03165F}, faupublication = {yes}, journal = {Energy and Environmental Science}, note = {EAM Import::2019-03-14}, pages = {1083-1094}, peerreviewed = {Yes}, title = {{Industrially} scalable and cost-effective {Mn2}+ doped {ZnxCd1}-{xS}/{ZnS} nanocrystals with 70% photoluminescence quantum yield, as efficient down-shifting materials in photovoltaics}, volume = {9}, year = {2016} } @article{faucris.108353124, abstract = {We have investigated the influence of As substrate passivation on the electronic level alignment of the heterovalent BeTe/Si(111) interface. Employing photoelectron spectroscopy, we have performed k-resolved measurements at selected excitation energies in the uv range to maximize the contribution from the F point for a correct determination of the valence band maximum. These results are compared with k-integrated data using a density-of-states function from density functional theory. For BeTe(100) and BeTe(111), we find a negligible influence of surface orientation on the position of the valence band maximum. The As passivation increases the valence band offset by 0.24 eV (&plusmn;0.13 eV) compared to BeTe on an unpassivated Si substrate, thus leading to a significantly increased step in the valence band (0.37&plusmn;0.13 eV). The results are discussed with respect to the barriers for electron and hole injection in heterostructures and with respect to the interface structure.}, author = {Gleim, Thomas and Weinhardt, L. and Schmidt, Th. and Fink, Rainer and Heske, C. and Umbach, E. and Hansen, L. and Landwehr, G. and Waag, A. and Fleszar, A. and Richter, B. and Ammon, Christian and Probst, Marc and Steinrück, Hans-Peter}, doi = {10.1103/PhysRevB.67.205315}, faupublication = {yes}, journal = {Physical Review B}, pages = {2053151-2053156}, peerreviewed = {Yes}, title = {{Influence} of {As} passivation on the electronic level alignment at {BeTe}/{Si}(111) interfaces}, volume = {67}, year = {2003} } @article{faucris.108284924, abstract = {Angle-resolved X-ray photoelectron spectroscopy has been used to study the influence of different types of anions on the surface composition of ionic liquids (ILs). We have investigated nine ILs with the same cation, 1-octyl-3-methylimidazolium [CCIm], but very different anions. In all cases, an enrichment of the cation alkyl chains is found at the expense of the polar cation head groups and the anions in the first molecular layer. This enhancement effect decreases with increasing size of the anion, which means it is most pronounced for the smallest anions and least pronounced for the largest anions. A simple model is proposed to explain the experimental observations. &copy; 2009 American Chemical Society.}, author = {Kolbeck, Claudia and Cremer, Till and Lovelock, Kevin and Paape, Natalia and Schulz, Peter and Wasserscheid, Peter and Maier, Florian and Steinrück, Hans-Peter}, doi = {10.1021/jp902978r}, faupublication = {yes}, journal = {Journal of Physical Chemistry B}, pages = {8682-8688}, peerreviewed = {Yes}, title = {{Influence} of different anions on the surface composition of ionic liquids studied using {ARXPS}}, volume = {113}, year = {2009} } @article{faucris.108285364, abstract = {Angle resolved X-ray photoelectron spectroscopy has been used to study the surface composition of various nonfunctionalized and functionalized 1,3-dialkylimidazolium ionic liquids. For [C C Im][Tf N] (where n ) 2-16), an enrichment of the aliphatic carbon was observed for longer chains (n &ge; 4). Enrichment of the aliphatic carbon also occurs for alkyl chains attached to the anion, as observed for [C C Im][OcOSO ]. Oligo(ethyleneglycol)ether (PEG) functionalities in the cation lead to a surface composition close to bulk stoichiometry and thus a loss in enrichment of the chains. This effect is attributed to attractive interactions between the oxygen atoms on the cation to the hydrogen atoms on the imidazolium ring for [Et(EG) MIm][Tf N] and [Me(EG) MIm][Tf N]. &copy; 2009 American Chemical Society.}, author = {Lovelock, Kevin and Kolbeck, Claudia and Cremer, Till and Paape, Natalia and Schulz, Peter and Wasserscheid, Peter and Maier, Florian and Steinrück, Hans-Peter}, doi = {10.1021/jp810637d}, faupublication = {yes}, journal = {Journal of Physical Chemistry B}, pages = {2854-2864}, peerreviewed = {Yes}, title = {{Influence} of different substituents on the surface composition of ionic liquids studied using {ARXPS}}, volume = {113}, year = {2009} } @article{faucris.108263804, abstract = {We investigated the adsorption and reaction of SO on clean and oxygen precovered, flat, and regularly stepped Pt surfaces, Pt(111), Pt(322), and Pt(355) by in situ high resolution X-ray photoelectron spectroscopy. Induced by the steps and/or the coadsorbed oxygen, several new SO species are observed, in addition to the two known SO species on Pt(111). On all investigated surfaces, a hit and stick mechanism is found for the adsorption, and no diffusion from terrace to step sites occurs at low temperatures. For the oxygen free stepped surfaces, a higher reactivity toward SO dissociation/disproportionation is found compared to Pt(111). On all three oxygen precovered Pt surfaces some SO is already formed directly upon SO exposure at low temperatures. Heating of this mixed O/SO layers first results in oxidation of more SO to SO, and at higher temperatures in subsequent oxidation of SO to SO, which finally decomposes above 450 K. The different reactions show a significant influence of the steps. © 2010 American Chemical Societ}, author = {Streber, Regine and Papp, Christian and Lorenz, Michael Peter Andreas and Höfert, Oliver and Zhao, Wei and Wickert, Sandra and Darlatt, Erik and Bayer, Andreas and Denecke, Reinhard and Steinrück, Hans-Peter}, doi = {10.1021/jp105994f}, faupublication = {yes}, journal = {Journal of Physical Chemistry C}, pages = {19734-19743}, peerreviewed = {Yes}, title = {{Influence} of steps on the adsorption and thermal evolution of {SO2} on clean and oxygen precovered {Pt} surfaces}, volume = {114}, year = {2010} } @article{faucris.108355984, abstract = {The activated adsorption of methane was investigated on two stepped Pt(355) and Pt(322) surfaces by timedependent in situ high-resolution X-ray photoelectron spectroscopy (XPS) combined with a supersonic molecular beam and was compared to corresponding results on Pt(111). Both stepped surfaces have five atom row wide (111) terraces but a different step orientation, namely, (111) and (100), respectively. Independent of the kinetic energy (0.45-0.83 eV) of impinging methane (CH or CD), methyl is formed on all surfaces upon adsorption at 120 K. For the stepped surfaces, two different methyl species are identified from the XP spectra, which are attributed to adsorption at terrace sites and at step sites. The total initial sticking coefficients (for terrace + step sites) and the total coverages are very similar for all three surfaces. At low coverages, diffusion of methyl from the terraces to the steps is significantly stronger on Pt(355) than on Pt(322), and the step saturation coverage is higher on Pt(355). The thermal evolution of methyl was also investigated by in situ temperature-programmed XPS. Overall, an enhanced reactivity toward dehydrogenation to methylidyne is found for both terrace and step sites on the stepped surfaces, with the (111) steps of Pt(355) exhibiting the highest activity. &copy; 2007 American Chemical Society.}, author = {Papp, Christian and Tränkenschuh, Barbara and Streber, Regine and Fuhrmann, Thomas and Denecke, Reinhard and Steinrück, Hans-Peter}, doi = {10.1021/jp066268f}, faupublication = {yes}, journal = {Journal of Physical Chemistry C}, pages = {2177-2184}, peerreviewed = {Yes}, title = {{Influence} of steps on the adsorption of methane on platinum surfaces}, volume = {111}, year = {2007} } @article{faucris.109607344, abstract = {We have performed a systematic study addressing the surface behavior of a variety of functionalized and non-functionalized ionic liquids (ILs). From angle-resolved X-ray photoelectron spectroscopy, detailed conclusions on the surface enrichment of the functional groups and the molecular orientation of the cations and anions is derived. The systems include imidazolium-based ILs methylated at the C2 position, a phenyl-functionalized IL, an alkoxysilane-functionalized IL, halo-functionalized ILs, thioether- functionalized ILs, and amine-functionalized ILs. The results are compared with the results for corresponding non-functionalized ILs where available. Generally, enrichment of the functional group at the surface is only observed for systems that have very weak interaction between the functional group and the ionic head groups. Scratching the surface: The surface behavior of various functionalized ionic liquids (ILs) is studied by angle-resolved X-ray photoelectron spectroscopy and conclusions on surface-enrichment effects and molecular orientation of cations and anions are derived (see figure; Im=imidazolium, Tf=trifluoromethanesulfonyl). Overall, surface enrichment is only observed for functional groups that interact weakly with the ionic head groups. &copy; 2014 WILEY-VCH Verlag GmbH &amp; Co. KGaA, Weinheim.}, author = {Kolbeck, Claudia and Niedermaier, Inga and Deyko, Alexey and Lovelock, Kevin and Taccardi, Nicola and Wei, Wei and Wasserscheid, Peter and Maier, Florian and Steinrück, Hans-Peter}, doi = {10.1002/chem.201304549}, faupublication = {yes}, journal = {Chemistry - A European Journal}, pages = {3954-3965}, peerreviewed = {Yes}, title = {{Influence} of substituents and functional groups on the surface composition of ionic liquids}, volume = {20}, year = {2014} } @article{faucris.123790524, author = {Franke, Matthias and Marchini, Florencia and Jux, Norbert and Steinrück, Hans-Peter and Lytken, Ole and Williams, Federico J.}, doi = {10.1002/chem.201602145}, faupublication = {yes}, journal = {Chemistry - A European Journal}, keywords = {ion exchange; metalation; porphyrins; solid–liquid interfaces; zinc}, peerreviewed = {unknown}, title = {{Inside} {Back} {Cover}: {Zinc} {Porphyrin} {Metal}-{Center} {Exchange} at the {Solid}–{Liquid} {Interface} ({Chem}. {Eur}. {J}. 25/2016)}, volume = {22}, year = {2016} } @article{faucris.107116284, abstract = {Using temperature-programmed desorption (TPD), the self-metalation and dehydrogenation of deuterated 5,10,15,20-tetraphenyl-21,23D-porphyrin on Cu(111) has been studied, resulting in new insight into the metalation of porphyrins on surfaces. The metalation is found to proceed through the transfer of the central aminic hydrogen atoms to the Cu(111) surface and not, as suggested by gas phase calculations, through the combination of the hydrogen atoms to molecular hydrogen above the partially inserted metal center. This finding suggests that the metalation reaction could be significantly influenced by the stability of hydrogen on the substrate surface. The metalation reaction and the subsequent hydrogenation and dehydrogenation of theperiphery of the porphyrin molecule leading to hydrogen-deuterium exchange are modeled with a simple microkinetic reaction model. The model is able to d escribe the main features of the TPD spectra.}, author = {Röckert, Michael and Franke, Matthias and Tariq, Quratulain and Lungerich, Dominik and Jux, Norbert and Stark, Michael Werner and Kaftan, Andre and Ditze, Stefanie and Marbach, Hubertus and Laurin, Mathias and Libuda, Jörg and Steinrück, Hans-Peter and Lytken, Ole}, doi = {10.1021/jp507303h}, faupublication = {yes}, journal = {Journal of Physical Chemistry C}, pages = {26729--26736}, peerreviewed = {Yes}, title = {{Insights} in the {Reaction} {Mechanistics}: {Isotopic} {Exchange} {During} the {Metalation} of {Deuterated} {Tetraphenyl}-21,{23D}-porphyrin on {Cu}(111)}, volume = {118}, year = {2014} } @article{faucris.120336084, abstract = {A systematic study of ionic liquid surfaces by angle resolved X-ray photoelectron spectroscopy (ARXPS) is presented. By reviewing recent and presenting new results for imidazolium-based ionic liquids (ILs), we discuss the impact of chemical differences on surface composition and on surface enrichment effects. (1) For the hydrophilic ethylene glycol (EG) functionalised ILs [Me(EG)MIm][TfN], [Et(EG)MIm][TfN] and [Me(EG)MIm][TfN], which vary in the number of ethylene glycol units (from 1 to 3), we find that the surface composition of the near-surface region is in excellent agreement with the bulk composition, which is attributed to attractive interactions between the oxygen atoms on the cation to the hydrogen atoms on the imidazolium ring. (2) For [CC Im][TfN] (where n = 1-16), i.e. ILs with an alkyl chain of increasing length, an enrichment of the aliphatic carbons is observed for longer chains (n &gt; 2), at the expense of the polar cation head groups and the anions in the first molecular layer, both of which are located approximately at the same distance from the outer surface. (3) To study the influence of the anion on the surface enrichment, we investigated ten ILs [CC Im][X] with the same cation, but very different anions [X] . In all cases, surface enrichment of the cation alkyl chains is found, with the degree of enrichment decreasing with increasing size of the anion, i.e., it is most pronounced for the smallest anions and least pronounced for the largest anions. (4) For the IL mixture [CC Im][TfN] and [CCIm][Tf N] we find a homogeneous distribution in the outermost surface region with no specific enrichment of the [CCIm] cation. &copy; 2010 the Owner Societies.}, author = {Maier, Florian and Cremer, Till and Kolbeck, Claudia and Lovelock, Kevin and Paape, Natalia and Schulz, Peter and Wasserscheid, Peter and Steinrück, Hans-Peter}, doi = {10.1039/b920804f}, faupublication = {yes}, journal = {Physical Chemistry Chemical Physics}, pages = {1905-1915}, peerreviewed = {Yes}, title = {{Insights} into the surface composition and enrichment effects of ionic liquids and ionic liquid mixtures}, volume = {12}, year = {2010} } @article{faucris.108357744, abstract = {In this contribution we introduce a new apparatus combining high-resolution photoelectron spectroscopy and supersonic molecular beam techniques designed to follow simple surface reactions like adsorption, desorption or oxidation in situ in a time- and temperature-resolved manner. Using high brightness synchrotron radiation high resolution core-level spectra can be obtained in less than 3 s. The molecular beam allows for local pressures of up to 1 &middot; 10 mbar and translational energies of the molecules of up to 2 eV in the case of CO. Preliminary examples of CO adsorption on Pt(111) are shown, where kinetic parameters can be derived from the coverage dependence of the different adsorption sites.}, author = {Denecke, Reinhard and Kinne, Martin and Whelan, Caroline and Steinrück, Hans-Peter}, doi = {10.1142/S0218625X0200297X}, faupublication = {yes}, journal = {Surface Review and Letters}, pages = {797-801}, peerreviewed = {Yes}, title = {{In}-situ core-level photoelectron spectroscopy of adsorbates on surfaces involving a molecular beam - {General} setup and first experiments}, volume = {9}, year = {2002} } @article{faucris.108361484, abstract = {High-resolution X-ray photoelectron spectroscopy (XPS) and temperature-programmed XPS at BESSY II have been applied to investigate the adsorption and desorption of NO on a Pt(1 1 1) surface. The coverage and temperature-dependent bonding configurations of NO have been identified from adsorbate O 1s and substrate Pt 4f core-level photoemission spectra, which were collected in situ during NO uptake or heating with data collection times per spectrum between 4 and 7 s. At 110 K, NO molecularly adsorbs on Pt(1 1 1) and sequentially populates three different adsorption sites. Up to coverages of 0.25 ML, only fcc-hollow sites are occupied, leading to the formation of a (2 &times; 2)-NO adsorbate structure. As coverage increases, in addition on-top sites are populated until at 0.5 ML a (2 &times; 2)-2NO structure is formed, which also represents the saturation structure at 250 K. Further increasing the coverage at 110 K leads to the occupation of hcp-hollow sites; at saturation, a (2 &times; 2)-3NO structure is observed with a coverage of 0.75 ML. Upon heating, the desorption of NO from the hcp-hollow sites gives rise to a desorption peak at 190 K. Further heating induces the desorption of on-top NO species starting at 275 K and fcc-hollow NO species starting at 320 K. No dissociation takes place. &copy; 2003 Elsevier Science B.V. All rights reserved.}, author = {Zhu, Junfa and Kinne, Martin and Fuhrmann, Thomas and Denecke, Reinhard and Steinrück, Hans-Peter}, doi = {10.1016/S0039-6028(03)00298-X}, faupublication = {yes}, journal = {Surface Science}, pages = {384-396}, peerreviewed = {Yes}, title = {{In} situ high-resolution {XPS} studies on adsorption of {NO} on {Pt}(1 1 1)}, volume = {529}, year = {2003} } @article{faucris.107802904, abstract = {Since the advent of third generation synchrotron light sources optimized for providing soft X-rays up to 2 keV, X-ray photoelectron spectroscopy (XPS) has been developed to be an outstanding tool to study surface properties and surface reactions at an unprecedented level. The high resolution allows identifying various surface species, and for small molecules even the vibrational fine structure can be resolved in the XP spectra. The high photon flux reduces the required measuring time per spectrum to the domain of a few seconds or even less, which enables to follow surface processes in situ. Moreover, it also provides access to very small coverages down to below 0.1% of a monolayer, enabling the investigation of minority species or processes at defect sites. The photon energy can be adjusted according to the requirement of a particular experiment, i.e., to maximize or minimize the surface sensitivity or the photoionization cross-section of the substrate or the adsorbate. For a few instruments worldwide, a next step forward was taken by combining in situ high-resolution spectrometers with supersonic molecular beams. These beams allow to control and vary the kinetic and internal energies of the incident molecules and provide a local pressure of up to ~10 mbar, which can be switched on and off in a controllable way, thus offering a well-defined time structure to study adsorption or reaction processes. Herein, we will review some specific scientific aspects which can be addressed by in situ XPS in order to demonstrate the power and potential of the method: In particular, the following topics will be addressed: (1) The sensitivity of the binding energy to adsorption sites will be analyzed, using CO on metals as example. From measurements at different temperatures, the binding energy difference between different sites can be derived, and exchange processes between different adsorbate species at step edges can be followed. (2) The vibrational fine structure of adsorbed small hydrocarbon species on metal surfaces will be analyzed in detail. We will first introduce the linear coupling model, then discuss the properties of adsorbed methyl and of a number of other small hydrocarbons, and show that the vibrational signature can be used as fingerprint for identifying surface species. (3) It is demonstrated that the binding energy of equivalent atoms in a molecule can be differentially changed by adsorption to a substrate; this sensitivity to the local environment will be discussed for adsorbed ethylene, benzene and graphene. (4) By temperature programmed XPS, the thermal evolution of adsorbed species can be followed in great detail, allowing for the identification of reaction intermediates and the determination of their stabilities. (5) The investigation of reaction kinetics by isothermal XPS measurements will be discussed; here results for the oxidation of sulfur and of CO will be presented and the corresponding activation energies of the rate limiting steps will be determined. &copy; 2013 Elsevier B.V.}, author = {Steinrück, Hans-Peter and Papp, Christian}, doi = {10.1016/j.surfrep.2013.10.003}, faupublication = {yes}, journal = {Surface Science Reports}, pages = {446-487}, peerreviewed = {Yes}, title = {{In} situ high-resolution {X}-ray photoelectron spectroscopy – {Fundamental} insights in surface reactions}, volume = {68}, year = {2013} } @article{faucris.107803784, abstract = {We systematically investigate the adsorption of benzene on Pt(111), Pt(355) and Pt(322) surfaces by high-resolution X-ray photoelectron spectroscopy (XPS) and first-principle calculations based on density functional theory (DFT), including van der Waals corrections. By comparing the adsorption energies at 1/9, 1/16 and 1/25 ML on Pt(111), we find significant lateral interactions exist between the benzene molecules at 1/9 ML. The adsorption behavior on Pt(355) and Pt(322) is very different. While on Pt(355) a step species is clearly identified in the C 1s spectra at low coverages followed by occupation of a terrace species at high coverages, no evidence for a step species is found on Pt(322). These different adsorption sites are confirmed by extensive DFT calculations, where the most favorable adsorption configurations on Pt(355) and Pt(322) are also found to vary: a highly distorted across the step molecule is found on Pt(355) while a less distorted configuration adjacent to the step molecule is deduced for Pt(322). The theoretically proposed C 1s core level binding energy shifts between these most favorable configurations and the terrace species are found to correlate well with experiment: for Pt(355), two adsorbate states are found, separated by &sim;0.4 eV in XPS and 0.3 eV in the calculations, in contrast to only one state on Pt(322). &copy; 2013 the Owner Societies.}, author = {Zhang, Renqin and Hensley, Alyssa J. and Mcewen, Jean-Sabin and Wickert, Sandra and Darlatt, Erik and Fischer, Kristina and Schöppke, Matthias and Denecke, Reinhard and Streber, Regine and Lorenz, Michael Peter Andreas and Papp, Christian and Steinrück, Hans-Peter}, doi = {10.1039/c3cp53127a}, faupublication = {yes}, journal = {Physical Chemistry Chemical Physics}, pages = {20662-20671}, peerreviewed = {Yes}, title = {{Integrated} {X}-ray photoelectron spectroscopy and {DFT} characterization of benzene adsorption on {Pt}(111), {Pt}(355) and {Pt}(322) surfaces}, volume = {15}, year = {2013} } @article{faucris.113269024, abstract = {We studied the interplay between Ag decoration of a stepped Pt(355) surface and CO adsorption by in situ high-resolution x-ray photoelectron spectroscopy. Varying amounts of Ag deposited at 300 K initially lead to a row-by-row growth starting from the lower Pt step edges. Such decoration of the step sites results in a change in the CO adsorption behavior. An apparent blocking of step sites for low CO coverages is attributed to a change in the electronic structure, resulting in a C 1s binding energy of CO at step sites being equal to that for CO at terrace on-top sites in the presence of Ag. Higher CO coverages induce the formation of embedded Ag clusters within the upper terraces, thus freeing up a part of the original Pt step sites for CO adsorption, as was derived by a comparison to density functional theory calculations in the corresponding surface models. &copy; 2009 American Institute of Physics.}, author = {Streber, Regine and Tränkenschuh, Barbara and Schöck, Johannes and Papp, Christian and Steinrück, Hans-Peter and Mcewen, J. -S. and Gaspard, P. and Denecke, Reinhard}, doi = {10.1063/1.3190201}, faupublication = {yes}, journal = {Journal of Chemical Physics}, peerreviewed = {Yes}, title = {{Interaction} between silver nanowires and {CO} on a stepped platinum surface}, volume = {131}, year = {2009} } @article{faucris.108361704, abstract = {The interaction of cobalt(II) tetraphenylporphyrin (CoTPP) and cobalt(II) tetrakis-(3,5-di-tert-butylphenyl)-porphyrin (CoTTBPP) with a Ag(111) surface has been investigated with photoelectron spectroscopy (XPS/ UPS). It is demonstrated that these adsorbed metal complexes are excellent model systems for studying the electronic interaction between a coordinated metal ion and a metal surface. The photoelectron spectra and work function data provide evidence that the electronic interaction between the cobalt ion and the silver surface results in a transfer of electron density from the surface to the ion. The presence of an additional electronic state located &sim;1 eV above the singly occupied molecular orbital (SOMO) of the metalloporphyrins is consistent with a molecular orbital (MO) model of the Co-Ag interaction as is the fact that the energetic position of this state depends on the distance between the Co ion and the Ag surface. The adsorbate-induced work function changes for the saturated monolayers amount to -0.72 eV for CoTPP and -0.91 eV for CoTTBPP. For comparison, we also present data of monolayer films of tetraphenylporphyrin and zinc(II) tetraphenylporphyrin. &copy; 2007 American Chemical Society.}, author = {Jux, Norbert and Maier, Florian and Steinrück, Hans-Peter and et al.}, author_hint = {Lukasczyk T., Flechtner K., Merte L.R., Jux N., Maier F., Gottfried J.M., Steinrück H.-P.}, doi = {10.1021/jp0652345}, faupublication = {yes}, journal = {Journal of Physical Chemistry C}, pages = {3090-3098}, peerreviewed = {Yes}, support_note = {Author relations incomplete. You may find additional data in field 'author{\_}hint'}, title = {{Interaction} of cobalt({II}) tetraarylporphyrins with a {Ag}(111) surface studied with photoelectron spectroscopy}, volume = {111}, year = {2007} } @article{faucris.120313644, abstract = {From a different angle: Thin films of functionalized ionic liquids are deposited on cerium oxides following a surface science approach. The functionalization of the alkyl chain changes its orientation with respect to the surface plane from normal to parallel. This then leads to a different surface chemistry at higher temperatures. Copyright &copy; 2013 WILEY-VCH Verlag GmbH &amp; Co. KGaA, Weinheim.}, author = {Schernich, Stefan and Laurin, Mathias and Lykhach, Yaroslava and Tsud, Nataliya and Sobota, Marek and Skala, Tomas and Prince, Kevin C. and Taccardi, Nicola and Wagner, Valentin and Steinrück, Hans-Peter and Matolin, Vladimir and Wasserscheid, Peter and Libuda, Jörg}, doi = {10.1002/cphc.201300792}, faupublication = {yes}, journal = {ChemPhysChem}, pages = {3673-3677}, peerreviewed = {Yes}, title = {{Interactions} of imidazolium-based ionic liquids with oxide surfaces controlled by alkyl chain functionalization}, volume = {14}, year = {2013} } @article{faucris.108085824, abstract = {Mixed self-assembled monolayers of C60-functionalized and different long-chained insulating phosphonic acids provide molecular scale non-volatile memory dielectrics for low-voltage organic thin-film transistors. The memory retention depends on the insulation of the C60 moiety and can be improved by embedding into the insulating SAM matrix and covering by corresponding insulating molecules.}, author = {Khassanov, Artöm and Schmaltz, Thomas and Steinrück, Hans-Peter and Magerl, Andreas and Hirsch, Andreas and Halik, Marcus}, doi = {10.1002/admi.201400238}, faupublication = {yes}, journal = {Advanced Materials Interfaces}, pages = {n/a}, peerreviewed = {Yes}, title = {{Interface} {Engineering} of {Molecular} {Charge} {Storage} {Dielectric} {Layers} for {Organic} {Thin}-{Film} {Memory} {Transistors}}, url = {http://onlinelibrary.wiley.com/doi/10.1002/admi.201400238/abstract}, volume = {1}, year = {2014} } @article{faucris.113261104, abstract = {The adsorption of Ca on electron-irradiated poly(3-hexylthiophene) (P3HT) surfaces at 300 K (E = 100 eV) has been studied by adsorption microcalorimetry, atomic beam/surface scattering, X-ray photoelectron spectroscopy (XPS), and low-energy He ion scattering spectroscopy (LEIS). The results are compared to previous studies of Ca adsorption on pristine P3HT. The major structural effect of electron irradiation is a substantial increase in the fraction of unsaturated carbon atoms, probably a result of electron-induced hydrogen abstraction from the hexyl chains and formation of new C=C double bonds. No loss of sulfur was observed. The combined XPS, LEIS, and calorimetry data indicate that the reaction and growth behavior of Ca on P3HT surfaces is not significantly affected by this electron damage, apart from an increased sticking probability at low coverages. The sticking probability of Ca on the irradiated P3HT is initially 0.63, compared to 0.36 on the pristine surface. It increases with coverage, approaching unity between 4 and 5 ML. The heat of adsorption stays nearly constant at 405 kJ/mol up to a coverage of 0.6 ML, which is ascribed to Ca diffusing below the surface and forming CaS clusters by abstraction of sulfur from the thiophene rings, based on XPS and LEIS data. The heat of adsorption then decreases gradually until it reaches the heat of sublimation of bulk Ca, 178 kJ/mol, by 4 ML; this is attributed to the formation of 3D Ca islands on top of the polymer, which eventually coalesce into a continuous Ca film by 11 ML. The heat of reaction versus coverage and the ultimate depth up to which the Ca atoms react with the polymer thiophene groups (&sim;3 nm) are nearly independent of electron damage, except for a difference in the heat of adsorption below 0.1 ML associated with defects or impurities. The increase in initial sticking probability caused by electron damage is attributed to stronger bonding of Ca adatoms to unsaturated versus saturated hydrocarbons. These very weakly held Ca adatoms are transient precursors to the two reactions which dominate the measured heat of adsorption (reaction with thiophene units and Ca cluster formation), but they can also desorb in this three-path kinetic competition. Mass spectrometer data show that these precursors have longer surface residence times on the electron-damaged surface. &copy; 2010 American Chemical Society.}, author = {Bebensee, Fabian and Zhu, Junfa and Baricuatro, J. H. and Farmer, Jason A. and Bai, Yun and Steinrück, Hans-Peter and Campbell, C. T. and Gottfried, Michael}, doi = {10.1021/la100209v}, faupublication = {yes}, journal = {Langmuir}, pages = {9632-9639}, peerreviewed = {Yes}, title = {{Interface} formation between calcium and electron-irradiated poly(3-hexylthiophene)}, volume = {26}, year = {2010} } @article{faucris.109744844, abstract = {We investigated the initial adsorption behavior and growth of thin films of ionic liquid (IL) [CCIm][TfN] on highly ordered pyrolytic graphite (HOPG) and on a full and a fractional graphene layer on Ni(111). We found that the initial adsorption behavior and growth strongly depended on the underlying substrate. On HOPG, the IL forms an initial wetting layer with a coverage of 0.5 ML and anions and cations next to each other in direct contact with the substrate. On a complete graphene layer on Ni(111), the wetting layer has twice the thickness with alternately oriented ion pairs next to each other. On top of these wetting layers, further IL growth occurs in 3D islands, with the island formation being less pronounced on the graphene layer. On the fractional graphene layer on Ni(111), initial IL adsorption preferentially occurs on bare Ni surface areas, with anions on top of cations, followed by 3D island growth on both the bare and the graphene-covered surface regions.}, author = {Rietzler, Florian and Nagengast, Jens and Steinrück, Hans-Peter and Maier, Florian}, doi = {10.1021/acs.jpcc.5b09649}, faupublication = {yes}, journal = {Journal of Physical Chemistry C}, pages = {28068-28076}, peerreviewed = {unknown}, title = {{Interface} of {Ionic} {Liquids} and {Carbon}: {Ultrathin} [{C1C1Im}][{Tf2N}] {Films} on {Graphite} and {Graphene}}, volume = {119}, year = {2015} } @article{faucris.113096764, abstract = {The surface of macroscopic films of the ternary molten salt mixture Li KCs[OAc] has been investigated by angle-resolved X-ray photoelectron spectroscopy (XPS) as a function of temperature. With increasing temperature a preferential depletion of K is observed by &sim;40%. From temperature programmed desorption we find that the onset for the cation desorption follows the order Cs, K, and Li, with activation energies of 125, 148, and 157 kJ mol, respectively; the corresponding value for the [OAc] anion is 147 kJ mol, which is, within the margin of error, identical to the average of the value found for the cations. Ultrathin films of the molten salt deposited on a Au(111) surface by physical vapor deposition show preferential enrichment of Cs, in line with the lower activation energy and thus higher desorption rate of Cs[OAc] from the ternary mixture. Angle-resolved XPS of the molten salt/gold interface demonstrates that the first molten salt monolayer grows in a layer-by-layer growth, followed by three-dimensional island growth at higher coverages. &copy; 2013 American Chemical Society.}, author = {Deyko, Alexey and Bajus, Stephanie and Rietzler, Florian and Bösmann, Andreas and Wasserscheid, Peter and Steinrück, Hans-Peter and Maier, Florian}, doi = {10.1021/jp407689c}, faupublication = {yes}, journal = {Journal of Physical Chemistry C}, pages = {22939-22946}, peerreviewed = {Yes}, title = {{Interface} properties and physicochemical characterization of the low-temperature molten salt {Li}/{K}/{Cs} acetate}, volume = {117}, year = {2013} } @article{faucris.121299684, abstract = {Ultrathin films of the ionic liquid 1,3-dimethylimidazolium bis(trifluoromethylsulfonyl)imide ([C C Im][Tf N]) were deposited on differently terminated Ni(111) single crystal surfaces. The initial wetting behaviour, the growth characteristics, the molecular arrangement at the interface, and thermal reactivity were investigated using angle-resolved X-ray photoelectron spectroscopy (ARXPS). On clean Ni(111), the initial growth occurs in a layer-by-layer mode. At submonolayer coverages up to at least 0.40 ML, a preferential arrangement of the IL ions in a bilayer structure, with the imidazolium cations in contact with the Ni surface atoms and the anions on top of the cation, is deduced. For higher coverages, a transition to a checkerboard-type arrangement occurs, which is most likely due to repulsive dipole-dipole interactions in the first layer. An overall preference for a checkerboard-type adsorption behaviour, i.e., anions and cations adsorbing next to each other, is found on the oxygen-precovered O(&radic;3&times;&radic;3)R30&deg;Ni(111) surface. The thermal stability of adsorbed IL layers on Ni(111) and on a fully oxidised Ni(111) surface was studied by heating the layers to elevated temperatures. For clean Ni(111) reversible adsorption takes place. For the oxidised surface, however, only cation-related moieties desorb, starting at &sim;450 K, while anion-related signals remain on the surface up to much higher temperatures. &copy; 2012 the Owner Societies.}, author = {Cremer, Till and Wibmer, Leonie and Krick Calderon, Sandra and Deyko, Alexey and Maier, Florian and Steinrück, Hans-Peter}, doi = {10.1039/c2cp40278e}, faupublication = {yes}, journal = {Physical Chemistry Chemical Physics}, pages = {5153-5163}, peerreviewed = {Yes}, title = {{Interfaces} of ionic liquids and transition metal surfaces - {Adsorption}, growth, and thermal reactions of ultrathin [{C} {1C} {1Im}] [{Tf} {2N}] films on metallic and oxidised {Ni}(111) surfaces}, volume = {14}, year = {2012} } @article{faucris.107810824, abstract = {Ultrathin films of two imidazolium-based ionic liquids (ILs), [C CIm][TfN] (=1-methyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide) and [CCIm][Tf N] (=1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide) were deposited on mica surfaces by physical vapor deposition in ultrahigh vacuum. Using angle-resolved X-ray photoelectron spectroscopy (ARXPS), the initial wetting behavior, the growth characteristics, and the molecular arrangement of the ions at the interface were investigated. The measurements were performed on freshly air-cleaved mica surfaces with different carbon precoverages. ARXPS clearly reveals that the initial IL adsorption behavior strongly depends on the amount of preadsorbed carbon: On clean mica, 3D growth (complete dewetting) occurs, whereas on a fully carbon covered surface, initially a complete 2D wetting layer forms, followed by 3D growth. &copy; 2013 American Chemical Society.}, author = {Deyko, Alexey and Cremer, Till and Rietzler, Florian and Perkin, Susan and Crowhurst, Lorna and Welton, Tom and Steinrück, Hans-Peter and Maier, Florian}, doi = {10.1021/jp3115397}, faupublication = {yes}, journal = {Journal of Physical Chemistry C}, pages = {5101-5111}, peerreviewed = {Yes}, title = {{Interfacial} behavior of thin ionic liquid films on mica}, volume = {117}, year = {2013} } @article{faucris.108265564, abstract = {Monolayers and multilayers of cobalt octaethylporphyrin (CoOEP), cobalt tetraphenylporphyrin (CoTPP) and the corresponding free-base porphyrins 2HOEP and 2HTPP on an Au(111) surface were investigated with X-ray and UV photoelectron spectroscopy (XPS and UPS). For CoTPP and CoOEP monolayers, the XP spectra show a characteristic splitting of the Co 2p signal, which suggests that only a fraction of the Co ions forms coordinative bonds to the Au(111) surface, while the others interact more weakly. This is a remarkable difference to previous results for CoOEP and CoTPP on Ag(111), where all Co ions in the monolayer were found to interact strongly and uniformly with the silver surface. Presumably, the lateral structural and electronic inhomogeneities of the reconstructed Au(111) surface are responsible for the more complex interaction behaviour on the gold surface. UP spectra of CoOEP and CoTPP monolayers show a new electronic state around 0.3 eV below the Fermi energy (E), i.e., at lower binding energy than in the case of Ag(111), where a strong signal appeared at 0.6 eV below E. In contrast, the free-base porphyrins 2HOEP and 2HTPP show no additional valence states in the monolayer, indicating that the Co ion plays a central role in the electronic interaction between the metal complexes and the substrate. These results have important implications for metal/organic interfaces in organic electronics or photovoltaic devices based on &pi;-conjugated semiconducting metal complexes, because the character of the chemical bond at the interface determines important parameters such as charge injecting rates. &copy; 2010 the Owner Societies.}, author = {Bai, Yun and Sekita, Michael and Schmid, Martin and Bischof, Thomas and Steinrück, Hans-Peter and Gottfried, Michael}, doi = {10.1039/b924974p}, faupublication = {yes}, journal = {Physical Chemistry Chemical Physics}, pages = {4336-4344}, peerreviewed = {Yes}, title = {{Interfacial} coordination interactions studied on cobalt octaethylporphyrin and cobalt tetraphenylporphyrin monolayers on {Au}(111)}, volume = {12}, year = {2010} } @article{faucris.110436304, abstract = {We have investigated the interactions between cobalt(II)-tetraphenylporphyrin (CoTPP) molecules and MgO( 100) thin films on Ag(100) by means of Synchrotron Radiation X-Ray and Ultra-Violet Photoelectron Spectroscopy (SR-XPS and SR-UPS). At room temperature, the CoTPP monolayer consists of two different species. A minority of molecules exhibits a strong electronic interaction with the substrate, whereas for the majority a similar spectroscopic signature as for multilayer molecules is observed. Based on the lateral inhomogeneity of the surface electronic structure, we tentatively suggest that the strongly interacting molecules adsorb with their metal center directly above oxygen ions. Unlike for metal substrates, where a monolayer can be prepared upon heating to above 500 K, most of the monolayer on MgO desorbs at 550 K together with the multilayers. This indicates either a weaker molecule- substrate bond than for most metal surfaces or a higher activation energy barrier for dehydrogenation. The remaining molecules are presumably MgTPP molecules, originating from a 2HTPP impurity in CoTPP.}, author = {Franke, Matthias and Wechsler, Daniel and Tariq, Quratulain and Röckert, Michael and Zhang, Liang and Thakur, Pardeep Kumar and Tsud, Nataliya and Bercha, Sofiia and Prince, Kevin and Lee, Tien-Lin and Steinrück, Hans-Peter and Lytken, Ole}, doi = {10.1039/c7cp00442g}, faupublication = {yes}, journal = {Physical Chemistry Chemical Physics}, pages = {11549-11553}, peerreviewed = {Yes}, title = {{Interfacial} interactions between {CoTPP} molecules and {MgO}(100) thin films}, volume = {19}, year = {2017} } @article{faucris.107830844, abstract = {The electronic structure of monolayers of iron(II) phthalocyanine (FePc), iron(II) octaethylporphyrin (FeOEP), and iron(II) tetraphenylporphyrin (FeTPP), adsorbed on Au(111), was examined with X-ray and UV photoelectron spectroscopy (XPS/UPS). Comparison of the Fe 2p signals of FePc multilayers and monolayers revealed an additional component in the monolayer signal with a binding energy characteristic of Fe(0). This component accounts for &sim;20% of the integral Fe 2p intensity, in agreement with previous observations on cobalt porphyrins on Au(111). The partial modification of the Fe 2p states suggests a laterally inhomogeneous interaction of the adsorbed molecules with the metal surface and is possibly related to the complex, reconstructed Au(111) surface morphology. Similar results obtained for FeTPP and FeOEP monolayers indicate that this effect is independent from the structure of the peripheral substituents on the core porphin moiety. The UP spectra of FePc and FeTPP monolayers show further indications for a substrate-molecule interaction mediated by the central Fe atom. In addition, FePc, FeTPP, and 2HTPP monolayers lead to a complete depopulation of the Shockley surface state of the clean Au(111) surface. &copy; 2011 American Chemical Society.}, author = {Schmid, Martin and Zirzlmeier, Johannes and Steinrück, Hans-Peter and Gottfried, J. Michael}, doi = {10.1021/jp204524s}, faupublication = {yes}, journal = {Journal of Physical Chemistry C}, pages = {17028-17035}, peerreviewed = {Yes}, title = {{Interfacial} interactions of iron({II}) tetrapyrrole complexes on {Au}(111)}, volume = {115}, year = {2011} } @article{faucris.227513940, abstract = {We have studied the adsorption and interfacial reactions of 2H-tetraphenylporphyrin (2HTPP) with cobalt-terminated Co3O4(111) and oxygen-terminated CoO(111) thin films using synchrotron-radiation X-ray photoelectron spectroscopy. Already at 275 K, we find evidence for the formation of a metalated species, most likely CoTPP, on both surfaces. The degree of self-metalation increases with temperature on both surfaces until 475 K, where the metalation is almost complete. At 575 K the porphyrin coverage decreases drastically on the reducible cobalt-terminated Co3O4(111) surface, while higher temperatures are needed on the non-reducible oxygen-terminated CoO(111). The low temperature self-metalation is similar to that observed on MgO(100) surfaces, but drastically different from that observed on TiO2(110), where no self-metalation is observed at room temperature.}, author = {Wechsler, Daniel and Fernandez, Cynthia C. and Tariq, Quratulain and Tsud, Nataliya and Prince, Kevin C. and Williams, Federico Jose and Steinrück, Hans-Peter and Lytken, Ole}, doi = {10.1002/chem.201902680}, faupublication = {yes}, journal = {Chemistry - A European Journal}, note = {CRIS-Team WoS Importer:2019-10-04}, peerreviewed = {Yes}, title = {{Interfacial} {Reactions} of {Tetraphenylporphyrin} with {Cobalt}-{Oxide} {Thin} {Films}}, year = {2019} } @article{faucris.119844604, abstract = {Based on density functional theory calculations combined with experimental results, we report and discuss an extremely distorted, &quot;inverted&#39;&#39; adsorption geometry of free-base tetraphenylporphyrin on Cu(111). The current findings yield new insights into a wellstudied system, shedding light on the peculiar molecule-substrate interaction and the resulting intramolecular conformation.}, author = {Lepper, Michael and Köbl, Julia and Schmitt, Tobias and Gurrath, Martin and De Siervo, Abner and Schneider, M. Alexander and Steinrück, Hans-Peter and Meyer, Bernd and Marbach, Hubertus and Hieringer, Wolfgang}, doi = {10.1039/c7cc04182a}, faupublication = {yes}, journal = {Chemical Communications}, pages = {8207-8210}, peerreviewed = {Yes}, title = {"{Inverted}'' porphyrins: a distorted adsorption geometry of free-base porphyrins on {Cu}(111)}, volume = {53}, year = {2017} } @article{faucris.120317824, abstract = {A fundamental challenge in lithographic and microscopic techniques employing focused electron beams are so-called proximity effects due to unintended electron emission and scattering in the sample. Herein, we apply a method that allows for visualizing electron induced surface modifications on a SiN substrate covered with a thin native oxide layer by means of iron deposits. Conventional wisdom holds that by using thin membranes proximity effects can be effectively reduced. We demonstrate that, contrary to the expectation, these can be indeed larger on a 200 nm SiN-membrane than on the respective bulk substrate due to charging effects. &copy; 2012 American Institute of Physics.}, author = {Walz, Marie-Madeleine and Vollnhals, Florian and Rietzler, Florian and Schirmer, Michael and Steinrück, Hans-Peter and Marbach, Hubertus}, doi = {10.1063/1.3681593}, faupublication = {yes}, journal = {Applied Physics Letters}, peerreviewed = {Yes}, title = {{Investigation} of proximity effects in electron microscopy and lithography}, volume = {100}, year = {2012} } @inproceedings{faucris.224997439, address = {WASHINGTON}, author = {Steinrück, Hans-Peter}, booktitle = {ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY}, date = {2019-03-31/2019-04-04}, faupublication = {yes}, note = {CRIS-Team WoS Importer:2019-08-23}, peerreviewed = {unknown}, publisher = {AMER CHEMICAL SOC}, title = {{Ionic} liquid adsorption and ion exchange processes at single crystal surfaces}, venue = {Orlando, FL}, year = {2019} } @article{faucris.108269304, abstract = {Towards a better understanding of novel catalytic materials consisting of supported noble metal catalysts modified by an ionic liquid (IL) film, we have performed a study under ultrahigh-vacuum (UHV) conditions. The model surface consists of Pd nanoparticles grown in UHV on an ordered alumina film on NiAl(110). Thin films of the room temperature IL 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide [BMIM][TfN] are deposited onto this surface by means of physical vapor deposition (PVD). The interaction of the IL with clean and CO-covered Pd/AlO/NiAl(110) at 300 K and the thermal behavior of the deposited IL films on Pd/AlO /NiAl(110) are investigated by time-resolved infrared reflection absorption spectroscopy (TR-IRAS) and X-ray photoelectron spectroscopy (XPS). At 300 K, the IL adsorbs molecularly both onto the Pd particles and onto the alumina. The IR spectra suggest that the [TfN] anions interact with Pd sites preferentially via the sulfonyl groups. CO pre-adsorbed on the Pd particles is partially displaced by the IL, even at 300 K, and only the part of CO adsorbed onto hollow sites on (111) facets of the Pd particles remains in place. Upon heating to temperatures higher than the desorption temperature of the IL (&gt;400 K), molecular desorption of the IL competes with decomposition. The decomposition products, atomic species and small fragments, remain preferentially adsorbed onto the Pd nanoparticles and strongly modify their surface properties. Most of the decomposition products originate from the [BMIM] cations, whereas the [TfN] anions desorb for the most part. &copy; 2010 the Owner Societies.}, author = {Sobota, Marek and Schmid, Martin and Happel, Markus and Amende, Maximilian and Maier, Florian and Steinrück, Hans-Peter and Paape, Natalia and Wasserscheid, Peter and Laurin, Mathias and Gottfried, Michael and Libuda, Jörg}, doi = {10.1039/c003753b}, faupublication = {yes}, journal = {Physical Chemistry Chemical Physics}, pages = {10610-10621}, peerreviewed = {Yes}, title = {{Ionic} liquid based model catalysis: {Interaction} of [{BMIM}][{Tf2N}] with {Pd} nanoparticles supported on an ordered alumina film}, volume = {12}, year = {2010} } @article{faucris.124154624, abstract = {Ionic liquids (ILs), salts with melting points below 100 &deg;C, represent a fascinating class of liquid materials typically characterized by an extremely low vapor pressure. Besides their application as new solvents or as electrolytes for electrochemical purposes, there are two important concepts of using ILs in catalysis: Liquid--liquid biphasic catalysis and IL thin film catalysis. Liquid--liquid biphasic catalysis enables either a very efficient manner to apply catalytic ILs, e.g. in Friedel--Crafts reactions, or to apply ionic transition metal catalyst solutions. In both cases, phase separation after reaction allows an easy separation of reaction products and catalyst re-use. One problem of liquid--liquid biphasic catalysis is mass transfer limitation. If the chemical reaction is much faster than the liquid--liquid mass transfer the latter limits the overall reaction rate. This problem is overcome in IL thin film catalysis where diffusion pathways and thus the characteristic time of diffusion are short. Here, Supported Ionic Liquid Phase (SILP) and Solid Catalyst with Ionic Liquid Layer (SCILL) are the two most important concepts. In both, a high surface area solid substrate is covered with a thin IL film, which contains either a homogeneously dissolved transition metal complex for SILP, or which modifies catalytically active surface sites at the support for SCILL. In each concept, interface phenomena play a very important role: These may concern the interface of an IL phase with an organic phase in the case of liquid--liquid biphasic catalysis. For IL thin film catalysis, the interfaces of the IL with the gas phase and with catalytic nanoparticles and/or support materials are of critical importance. It has recently been demonstrated that these interfaces and also the bulk of ILs can be investigated in great detail using surface science studies, which greatly contributed to the fundamental understanding of the catalytic properties of ILs and supported IL materials. Exemplary results concerning the IL/vacuum or IL/gas interface, the solubility and surface enrichment of dissolved metal complexes, the IL/support interface and the in situ monitoring of chemical reactions in ILs are presented.}, author = {Wasserscheid, Peter and Steinrück, Hans-Peter}, doi = {10.1007/s10562-014-1435-x}, faupublication = {yes}, journal = {Catalysis Letters}, keywords = {Heterogeneous catalysis;Catalysis;Homogeneous catalysis;Green chemistry;Evaporation;Methodology and Phenomena;XPS;Spectroscopy and General Characterisation;Ionic liquids;Preparation and Materials}, month = {Jan}, pages = {380--397}, peerreviewed = {Yes}, title = {{Ionic} {Liquids} in {Catalysis}}, volume = {145}, year = {2015} } @article{faucris.294847899, abstract = {Isolated active sites have great potential to be highly efficient and stable in heterogeneous catalysis, while enabling low costs due to the low transition metal content. Herein, we present results on the synthesis, first catalytic trials, and characterization of the Ga9Rh2 phase and the hitherto not-studied Ga3Rh phase. We used XRD and TEM for structural characterization, and with XPS, EDX we accessed the chemical composition and electronic structure of the intermetallic compounds. In combination with catalytic tests of these phases in the challenging propane dehydrogenation and by DFT calculations, we obtain a comprehensive picture of these novel catalyst materials. Their specific crystallographic structure leads to isolated Rhodium sites, which is proposed to be the decisive factor for the catalytic properties of the systems.}, author = {Wittkämper, Haiko and Hock, Rainer and Weißer, Matthias and Dallmann, Johannes and Vogel, Carola and Raman, Narayanan and Tacardi, Nicola and Haumann, Marco and Wasserscheid, Peter and Hsieh, Tzung En and Maisel, Sven and Moritz, Michael and Wichmann, Christoph and Frisch, Johannes and Gorgoi, Mihaela and Wilks, Regan G. and Bär, Marcus and Wu, Mingjian and Spiecker, Erdmann and Görling, Andreas and Unruh, Tobias and Steinrück, Hans-Peter and Papp, Christian}, doi = {10.1038/s41598-023-31157-y}, faupublication = {yes}, journal = {Scientific Reports}, note = {CRIS-Team Scopus Importer:2023-03-31}, pages = {4458-}, peerreviewed = {Yes}, title = {{Isolated} {Rh} atoms in dehydrogenation catalysis}, volume = {13}, year = {2023} } @article{faucris.110948464, abstract = {It is shown that the characteristic double-peak structure of the 2e band in the photoelectron spectra of CH and CD chemisorbed on metal surfaces arises from a fairly strong intramolecular multi-mode dynamical Jahn-Teller effect. An ab initio treatment of the multi-mode Jahn-Teller effect in the isolated 2e hole state of free benzene yields, after suitable broadening, a quantitative description of the band shape observed in the photoelectron spectra. In gas-phase benzene, the strong Jahn-Teller activity of the 2e hole is concealed by its overlapping and strong pseudo-Jahn-Teller coupling with the adjacent 1a hole state. &copy; 1991.}, author = {Eiding, J. and Domcke, W. and Huber, W. and Steinrück, Hans-Peter}, doi = {10.1016/0009-2614(91)87129-Y}, faupublication = {no}, journal = {Chemical Physics Letters}, pages = {133-138}, peerreviewed = {Yes}, title = {{Jahn}-{Teller} effect of the 2e2g level of chemisorbed benzene}, volume = {180}, year = {1991} } @article{faucris.121625504, abstract = {We report on the intercalation of graphene grown on a Ni(111) crystal with argon. Argon is implanted in the Ni(111) crystal by ion bombardment before graphene growth, and diffuses to the surface during the growth of graphene at elevated temperatures. Graphene acts as an atomically thin barrier and keeps the argon underneath. We investigated this system with high resolution X-ray photoelectron spectroscopy. From our experiments we determined the mean quantities of argon under graphene. From our analysis, a simple model to determine the pressure under the graphene layer is presented. In our measurements, we find an increased thermal stability of the intercalated graphene as compared to non-intercalated graphene on Ni(111).}, author = {Steinrück, Hans-Peter and Bauer, Udo and Gotterbarm, Karin and Späth, Florian and Papp, Christian and Höfert, Oliver and Gleichweit, Christoph and Amende, Maximilian}, doi = {10.1016/j.susc.2015.05.009}, faupublication = {yes}, journal = {Surface Science}, keywords = {Graphene; Intercalation; Nickel; XPS}, month = {Jan}, pages = {222-226}, peerreviewed = {Yes}, title = {{Keeping} argon under a graphene lid - {Argon} intercalation between graphene and nickel(111)}, volume = {643}, year = {2016} } @article{faucris.108370504, abstract = {We investigated the thermal evolution of methyl on Pt(1 1 1), Pt(3 2 2) and Pt(3 5 5) by in situ X-ray photoelectron spectroscopy. The dehydrogenation to methylidyne shows a pronounced kinetic isotope effect, with the characteristic temperature higher by 16 K for CD than for CH. The resulting difference in activation energies, 48 meV, agrees well with the difference in the zero point energies of the C-H and C-D stretching vibrations. For the stepped surfaces an enhanced reactivity is found. While dehydrogenation of methyl on Pt(3 2 2) at step and terrace sites occurs at the same temperature, for Pt(3 5 5) the steps are even more reactive. &copy; 2007 Elsevier B.V. All rights reserved.}, author = {Papp, Christian and Fuhrmann, Thomas and Tränkenschuh, Barbara and Denecke, Reinhard and Steinrück, Hans-Peter}, doi = {10.1016/j.cplett.2007.06.023}, faupublication = {yes}, journal = {Chemical Physics Letters}, pages = {176-181}, peerreviewed = {Yes}, title = {{Kinetic} isotope effects and reaction intermediates in the decomposition of methyl on flat and stepped platinum (1 1 1) surfaces}, volume = {442}, year = {2007} } @article{faucris.108375124, abstract = {The adsorption of CO on Pt(111) was examined in a time-resolved manner by high-resolution core level photoelectron spectroscopy using synchrotron radiation. From C1s, O1s, and Pt4f spectra, two species, namely on-top and bridge bound CO, were resolved with excellent agreement of binding energy values with literature reports.}, author = {Kinne, Martin and Fuhrmann, Thomas and Whelan, Caroline and Zhu, Junfa and Pantförder, Jörg and Probst, Marc and Held, Georg and Denecke, Reinhard and Steinrück, Hans-Peter}, doi = {10.1063/1.1522405}, faupublication = {yes}, journal = {Journal of Chemical Physics}, pages = {10852-10859}, peerreviewed = {Yes}, title = {{Kinetic} parameters of {CO} adsorbed on {Pt}(111) studied by in situ high resolution x-ray photoelectron spectroscopy}, volume = {117}, year = {2002} } @article{faucris.108299004, abstract = {We studied the influence of preadsorbed sulfur on the adsorption of CO on Pt(3 5 5) and Pt(3 2 2) by in situ X-ray photoelectron spectroscopy. At low temperatures, no adsorption of CO at steps is found, indicating a passivation by sulfur. Upon heating, population of step sites with CO occurs. This behavior is attributed to a kinetic passivation of the steps by sulfur at low temperatures, which is lifted upon heating. The characteristic transition temperatures of 185 K for Pt(3 5 5) and 240 K for Pt(3 2 2) are significantly different, due to a higher activation barrier for the CO/S site exchange process for Pt(3 2 2). &copy; 2007 Elsevier B.V. All rights reserved.}, author = {Streber, Regine and Papp, Christian and Lorenz, Michael Peter Andreas and Bayer, Andreas and Denecke, Reinhard and Steinrück, Hans-Peter}, doi = {10.1016/j.cplett.2007.12.038}, faupublication = {yes}, journal = {Chemical Physics Letters}, pages = {94-98}, peerreviewed = {Yes}, title = {{Kinetic} passivation of steps with sulfur and {CO}/{S} site exchange processes on stepped {Pt} surfaces}, volume = {452}, year = {2008} } @article{faucris.120902144, abstract = {The coadsorption and reaction of CO with atomic oxygen on Pt(111) was examined by in situ high-resolution core level spectroscopy using synchrotron radiation. A atomic oxygen layer with a coverage of 0.25 ML was exposed to CO from a supersonic molecular beam at various sample temperatures and pressures. X ray photoelectron spectra were collected at photon energies of 380 eV for C 1s and 650 eV for the O 1s region in normal emission geometry. From an Arrhenius plot of the rate constant between 275 and 305 K an activation energy of (0.53&plusmn;0.04) eV and a prefactor of 4.7&times;10 s were determined.}, author = {Kinne, Martin and Fuhrmann, Thomas and Zhu, Junfa and Whelan, Caroline and Denecke, Reinhard and Steinrück, Hans-Peter}, doi = {10.1063/1.1669378}, faupublication = {yes}, journal = {Journal of Chemical Physics}, pages = {7113-7122}, peerreviewed = {Yes}, title = {{Kinetics} of the {CO} oxidation reaction on {Pt}(111) studied by in situ high-resolution x-ray photoelectron spectroscopy}, volume = {120}, year = {2004} } @article{faucris.107831504, abstract = {We studied the reaction kinetics of sulfur oxidation on the Pd(100) surface by in situ high resolution x-ray photoelectron spectroscopy and ab initio density functional calculations. Isothermal oxidation experiments were performed between 400 and 500 K for small amounts (&sim;0.02 ML) of preadsorbed sulfur, with oxygen in large excess. The main stable reaction intermediate found on the surface is SO , with SO and SO being only present in minor amounts. Density-functional calculations depict a reaction energy profile, which explains the sequential formation of SO , SO , and eventually SO , also highlighting that the in-plane formation of SO from S and O adatoms is the rate limiting step. From the experiments we determined the activation energy of the rate limiting step to be 85 6 kJ mol by Arrhenius analysis, matching the calculated endothermicity of the SO formation. &copy; 2012 American Institute of Physics.}, author = {Gotterbarm, Karin and Luckas, Nicola and Höfert, Oliver and Lorenz, Michael Peter Andreas and Streber, Regine and Papp, Christian and Vines, Francesc and Steinrück, Hans-Peter and Görling, Andreas}, doi = {10.1063/1.3687676}, faupublication = {yes}, journal = {Journal of Chemical Physics}, peerreviewed = {Yes}, title = {{Kinetics} of the sulfur oxidation on palladium: {A} combined in situ x-ray photoelectron spectroscopy and density-functional study}, volume = {136}, year = {2012} } @article{faucris.120409344, abstract = {The adsorption of benzene and the coadsorption of benzene with electronegative coadsorbates on Ni(111) have been studied by angle-resolved UPS using linearly polarized synchrotron radiation. The electronic structure of benzene coadsorbed with NO, CO and O in the ordered (2 3&times;2 3)R30&deg; layers and for the coadsorbed (3 &times; 3) benzene + NO layer is similar to that of pure benzene layers. Uniform shifts of the various benzene levels to lower binding energy (0.2-0.3 eV) in the coadsorbed layers are attributed to electrostatic initial state effects. In all pure and coadsorbed layers studied, the benzene molecules are oriented with their molecular plane parallel to the surface with the molecular symmetry reduced to C . In the nonsaturated benzene layer and in the coadsorbed layers with (2 3&times;2 3)R30&deg; structure the molecules are azimuthally oriented with the hydrogens pointing along the [211] directions of the substrate. In the saturated pure ( 7&times; 7)R19.1&deg; layer and the (3 &times; 3) benzene + NO layer the molecules are azimuthally reorientated due to lateral interactions. The proposed azimuthal reorientations are in agreement with expectations from steric arguments. For the saturated pure ( 7&times; 7)R19.1&deg; layer the 2a levels exhibits a dispersion of 0.45 eV. also indicative of lateral interactions. &copy; 1991.}, author = {Huber, W. and Zebisch, P. and Bornemann, T. and Steinrück, Hans-Peter}, faupublication = {no}, journal = {Surface Science}, pages = {16-22}, peerreviewed = {Yes}, title = {{Lateral} interactions and azimuthal orientation of pure and coadsorbed benzene layers on {Ni}(111)}, url = {https://www.scopus.com/record/display.uri?eid=2-s2.0-0026414390&origin=inward}, volume = {258}, year = {1991} } @article{faucris.215786547, author = {Wild, Stefan and Fickert, Michael and Mitrovic, Aleksandra and Lloret Segura, Vicente Josep and Neiß, Christian and Alejandro Vidal-Moya, Jose and Angel Rivero-Crespo, Miguel and Leyva-Perez, Antonio and Werbach, Katharina and Peterlik, Herwig and Grabau, Mathias and Wittkämper, Haiko and Papp, Christian and Steinrück, Hans-Peter and Pichler, Thomas and Görling, Andreas and Hauke, Frank and Abellan Saez, Gonzalo and Hirsch, Andreas}, doi = {10.1002/anie.201811181}, faupublication = {yes}, journal = {Angewandte Chemie International Edition}, pages = {5763-5768}, peerreviewed = {Yes}, title = {{Lattice} {Opening} upon {Bulk} {Reductive} {Covalent} {Functionalization} of {Black} {Phosphorus}}, volume = {58}, year = {2019} } @article{faucris.108269964, abstract = {The chemical surface composition of Rh-containing ionic liquid solutions has been studied by angle-resolved X-ray photoelectron spectroscopy (ARXPS). Rh-tppts complexes of high relevance for multiphase hydroformylation catalysis showed remarkable surface activity, whereas non-tppts containing systems showed Rh depleting from the surface (tppts=tris(3-sodium sulfonatophenyl)phosphine). &copy; 2010 WILEY-VCH Verlag GmbH &amp; Co. KGaA, Weinheim.}, author = {Kolbeck, Claudia and Paape, Natalia and Cremer, Till and Schulz, Peter and Maier, Florian and Steinrück, Hans-Peter and Wasserscheid, Peter}, doi = {10.1002/chem.201000903}, faupublication = {yes}, journal = {Chemistry - A European Journal}, pages = {12083-12087}, peerreviewed = {Yes}, title = {{Ligand} effects on the surface composition of {Rh}-containing ionic liquid solutions used in hydroformylation catalysis}, volume = {16}, year = {2010} } @article{faucris.120902364, abstract = {A study on the determination for the locations of light atoms in CD on Ru was performed using low energy electron diffraction (LEED) and density functional theory (DFT). An upward bending of the C-D bonds of 16&deg; on average was found. The bending was observed to be not uniform but alternated between 9&deg; and 24&deg; for the inequivalent light atoms. The strong buckling behavior was explained in the terms of decreased aromaticity and a distortion of the molecule towards the chair geometry of cyclohexane.}, author = {Held, Georg and Braun, Wolfgang and Steinrück, Hans-Peter and Yamagishi, S. and Jenkins, S.J. and King, David A.}, doi = {10.1103/PhysRevLett.87.216102}, faupublication = {yes}, journal = {Physical Review Letters}, pages = {2161021-2161024}, peerreviewed = {Yes}, title = {{Light}-atom location in adsorbed benzene by experiment and theory}, volume = {87}, year = {2001} } @article{faucris.307282742, abstract = {The molecule pair of 1-cyclohexylethanol and acetophenone represents an interesting system for a chemical hydrogen storage cycle as it combines two different classes of so-called liquid organic hydrogen carriers (LOHCs), namely hydrogenated, formerly aromatic cyclic hydrocarbons and alcohols, i.e., hydrogenated carbonyls. In particular, the latter have recently attracted much attention due to their favorable dehydrogenation temperatures and the possibility to convert them directly into electricity in specially designed direct-LOHC fuel cells. Herein, we investigate the temperature-triggered dehydrogenation reaction of 1-cyclohexylethanol to acetophenone on a Pt(111) model catalyst using synchrotron-based temperature-programed X-ray photoelectron spectroscopy. To obtain a complete picture of the reaction mechanism, we consider not only the individual surface reactions of 1-cyclohexylethanol and acetophenone but also those of two potential dehydrogenation intermediates, namely, the partially dehydrogenated 1-cyclohexylethanone and 1-phenylethanol. We find a stepwise dehydrogenation of 1-cyclohexylethanol: the first step around ∼210 K at the alcohol moiety yields the ketone 1-cyclohexylethanone. The second step above ∼260 K at the cyclohexyl group is accompanied by the loss of an H-atom at the molecule’s methyl group and leads to the formation of an acetophenone-like phenyl-C(O)-CH<inf>2</inf> species at ∼340 K. The same species are also identified in the surface reactions of acetophenone, 1-phenylethanol, and 1-cyclohexylethanone in this temperature range. Overall, the system shows good thermal robustness: a complete dehydrogenation of the hydrogen-rich carrier occurs without damage to the carbon framework.}, author = {Schwaab, Valentin and Hemauer, Felix and Freiberger, Eva Marie and Waleska-Wellnhofer, Natalie and Steinrück, Hans-Peter and Papp, Christian}, doi = {10.1021/acs.jpcc.3c01969}, faupublication = {yes}, journal = {Journal of Physical Chemistry C}, note = {CRIS-Team Scopus Importer:2023-07-07}, peerreviewed = {Yes}, title = {{Liquid} {Organic} {Hydrogen} {Carriers}: {Model} {Catalytic} {Studies} on the {Thermal} {Dehydrogenation} of 1-{Cyclohexylethanol} on {Pt}(111)}, year = {2023} } @article{faucris.113095884, abstract = {We review recent results towards a molecular understanding of the adsorption and dehydrogenation of carbazole-derived liquid organic hydrogen carriers on platinum and palladium single crystals and on Al2O3-supported Pt and Pd nanoparticles. By combining synchrotron-based high-resolution X-ray photoelectron spectroscopy, infrared reflection-absorption spectroscopy, advanced molecular beam methods and temperature-programmed desorption spectroscopy, detailed insights into the reaction mechanism are obtained. On Pt(111), dehydrogenation of perhydro-N-ethylcarbazole, H-12-NEC, starts with activation of the hydrogen atoms at the pyrrole unit, yielding H-8-NEC as the first stable reaction intermediate at approximate to 340K, followed by further dehydrogenation to NEC at approximate to 380K. Above 390K, dealkylation starts, yielding carbazole as an undesired byproduct. On small supported Pt particles, the dealkylation sets in at lower temperatures, due to the higher reactivity of low-coordinated sites, while on larger particles with (111) facets a reactivity as on the flat surface is observed. Carbazole derivatives with ethyl, propyl and butyl chains show an overall very similar reactivity, both on Pt(111) and on Pt nanoparticles. When comparing the dealkylation behavior of H-12-NEC on Pt(111) and Pt nanoparticles to that on Pd(111) and Pd nanoparticles, we find a higher reactivity for the Pd systems.}, author = {Papp, Christian and Wasserscheid, Peter and Libuda, Jörg and Steinrück, Hans-Peter}, doi = {10.1002/tcr.201402014}, faupublication = {yes}, journal = {Chemical Record}, keywords = {dehydrogenation;liquid organic hydrogen carriers;platinum;renewable resources;surface chemistry}, pages = {879-896}, peerreviewed = {Yes}, title = {{Liquid} {Organic} {Hydrogen} {Carriers}: {Surface} {Science} {Studies} of {Carbazole} {Derivatives}}, volume = {14}, year = {2014} } @article{faucris.107831724, abstract = {Ultrathin films of two imidazolium-based ionic liquids (IL), [C CIm][TfN] (= 1,3-dimethylimidazolium bis(trifluoromethyl)imide) and [CCIm][TfN] (= 1-methyl-3-octylimidazolium bis(trifluoromethyl)imide) were prepared on a Au(111) single-crystal surface by physical vapor deposition in ultrahigh vacuum. The adsorption behavior, orientation, and growth were monitored via angle-resolved X-ray photoelectron spectroscopy (ARXPS). Coverage-dependent chemical shifts of the IL-derived core levels indicate that for both ILs the first layer is formed from anions and cations directly in contact with the Au surface in a checkerboard arrangement and that for [CC Im][TfN] a reorientation of the alkyl chain with increasing coverage is found. For both ILs, geometry models of the first adsorption layer are proposed. For higher coverages, both ILs grow in a layer-by-layer fashion up to thicknesses of at least 9 nm (&gt;10 ML). Moreover, beam damage effects are discussed, which are mainly related to the decomposition of [TfN] anions directly adsorbed at the gold surface. &copy; 2011 American Chemical Society.}, author = {Cremer, Till and Stark, Michael Werner and Deyko, Alexey and Steinrück, Hans-Peter and Maier, Florian}, doi = {10.1021/la105007c}, faupublication = {yes}, journal = {Langmuir}, pages = {3662-3671}, peerreviewed = {Yes}, title = {{Liquid}/solid interface of ultrathin ionic liquid films: [{C} {1C1Im}][{Tf2N}] and [{C8C} {1Im}][{Tf2N}] on {Au}(111)}, volume = {27}, year = {2011} } @article{faucris.121301664, abstract = {In order to expand the temperature limits of Supported Ionic Liquid Phase (SILP) or Solid Catalyst with Ionic Liquid Layer (SCILL) systems to higher operation temperatures, the mixture of lithium acetate, potassium acetate, and caesium acetate (molar ratio of 0.2/0.275/0.525) has been studied in detail. Physico-chemical properties of the bulk melt are reported together with stability data of the modern salt on various solid support materials showing attractive properties for many potential high temperature applications. &copy; 2012 The Royal Society of Chemistry.}, author = {Bajus, Stephanie and Deyko, Alexey and Bösmann, Andreas and Maier, Florian and Steinrück, Hans-Peter and Wasserscheid, Peter}, doi = {10.1039/c2dt31568h}, faupublication = {yes}, journal = {Dalton Transactions}, month = {Jan}, pages = {14433-14438}, peerreviewed = {Yes}, title = {{Low} melting {Li}/{K}/{Cs} acetate salt mixtures as new ionic media for catalytic applications - first physico-chemical characterization}, volume = {41}, year = {2012} } @article{faucris.108376004, abstract = {The low-temperature reactivity of water (DO) adsorbed on clean and oxygen pre-covered Cu(110) was studied using high resolution X-ray photoelectron spectroscopy (HRXPS) and low energy electron diffraction (LEED). On the clean surface partial dissociation to hydroxyl was observed already at 95 K. Upon annealing to 220 K hydrogen bonded water-hydroxyl chains are formed. Upon further annealing water desorbs leaving behind a layer of hydroxyl, most of which desorbs recombinatively eventually. With pre-adsorbed oxygen water reacts to hydroxyl lifting the added-row reconstruction even below 225 K. Upon annealing this adsorbate layer passes through essentially the same stages as without pre-adsorbed oxygen. © 2003 Elsevier B.V. All rights reserve}, author = {Ammon, Christian and Bayer, Andreas and Steinrück, Hans-Peter and Held, Georg}, doi = {10.1016/S0009-2614(03)01127-8}, faupublication = {yes}, journal = {Chemical Physics Letters}, pages = {163-169}, peerreviewed = {Yes}, title = {{Low}-temperature partial dissociation of water on {Cu}(110)}, volume = {377}, year = {2003} } @article{faucris.121302544, abstract = {We have prepared iron microwires in a combination of focused electron beam induced deposition and autocatalytic growth from the iron pentacarbonyl, Fe(CO), precursor gas under ultra-high vacuum conditions. The electrical transport properties of the microwires were investigated and it was found that the temperature dependence of the longitudinal resistivity (&rho;) shows a typical metallic behaviour with a room temperature value of about 88 &nu;&Omega; cm. In order to investigate the magnetotransport properties we have measured the isothermal Hall-resistivities in the range between 4.2 and 260 K. From these measurements, positive values for the ordinary and the anomalous Hall coefficients were derived. The relation between anomalous Hall resistivity (&rho;) and longitudinal resistivity is quadratic, , revealing an intrinsic origin of the anomalous Hall effect. Finally, at low temperature in the transversal geometry a negative magnetoresistance of about 0.2% was measured. &copy; 2011 IOP Publishing Ltd.}, author = {Porrati, F. and Sachser, R. and Walz, Marie-Madeleine and Vollnhals, Florian and Steinrück, Hans-Peter and Marbach, Hubertus and Huth, M.}, doi = {10.1088/0022-3727/44/42/425001}, faupublication = {yes}, journal = {Journal of Physics D-Applied Physics}, peerreviewed = {Yes}, title = {{Magnetotransport} properties of iron microwires fabricated by focused electron beam induced autocatalytic growth}, volume = {44}, year = {2011} } @article{faucris.119691264, abstract = {Based on a combined scanning tunnelling microscopy and X-ray photoelectron spectroscopy study we present detailed insights into pronounced changes of long-range order and intramolecular conformation during the self-metalation of 2H-5,10,15,20-tetrakis-(3,5-di-tert-butyl)-phenylporphyrin (2HTTBPP) to CuTTBPP on Cu(111). Upon metalation, the porphyrin literally ``pops up&#39;&#39; from the surface, due to a drastically reduced molecule--substrate interaction.}, author = {Stark, Michael Werner and Ditze, Stefanie and Lepper, Michael and Zhang, Liang and Schlott, Hannah and Buchner, Florian and Röckert, Michael and Chen, Min and Lytken, Ole and Steinrück, Hans-Peter and Marbach, Hubertus}, doi = {10.1039/c4cc03708a}, faupublication = {yes}, journal = {Chemical Communications}, pages = {10225--10228}, peerreviewed = {Yes}, title = {{Massive} conformational changes during thermally induced self-metalation of {2H}-tetrakis-(3,5-di-tert-butyl)-phenylporphyrin on {Cu}(111)}, volume = {50}, year = {2014} } @article{faucris.210452614, abstract = {We investigated the metalation and coordination reactions of Co with 2H-5,15-bis(para-cyanophenyl)10,20-bisphenylporphyrin (2HtransDCNPP) on a Ag(111) surface by scanning tunneling microscopy. At room temperature (RT), 2HtransDCNPPs self-assemble into a supramolecular structure stabilized by intermolecular hydrogen bonding. The metalation of 2HtransDCNPP is achieved either by depositing Co atoms onto the supramolecular structure at RT, or, alternatively, by depositing the molecules onto a submonolayer Co-precovered Ag(111) surface with a subsequent heating to 500 K. In addition, the molecules coordinate to Co atoms through the N atoms in the peripheral cyano groups with a preference of isolated 4-fold coordination motifs at RT.}, author = {Kuliga, Jan and Zhang, Liang and Lepper, Michael and Lungerich, Dominik and Hölzel, Helen and Jux, Norbert and Steinrück, Hans-Peter and Marbach, Hubertus}, doi = {10.1039/c8cp05255g}, faupublication = {yes}, journal = {Physical Chemistry Chemical Physics}, pages = {25062-25068}, peerreviewed = {Yes}, title = {{Metalation} and coordination reactions of {2H}-meso-trans-di(p-cyanophenyl) porphyrin on {Ag}(111) with coadsorbed cobalt atoms}, volume = {20}, year = {2018} } @article{faucris.248382035, abstract = {We study the interaction and metalation reaction of a free base 5,10,15,20-terakis(4-cyanophenyl)porphyrin (2HTCNPP) with post-deposited Zn atoms and the targeted reaction product Zn-5,10,15,20-terakis(4-cyanophenyl)porphyrin (ZnTCNPP) on a Ag(111) surface. The investigations are performed with scanning tunneling microscopy at room temperature after Zn deposition and subsequent heating. The goal is to obtain further insights in the metalation reaction and the influence of the cyanogroups on this reaction. The interaction of 2HTCNPP with post-deposited Zn leads to the formation of three different 2D ordered island types that coexist on the surface. All contain a new species with a bright appearance, which increases with the amount of post-deposited Zn. We attribute this to metastable SAT ("sitting atop") complexes formed by Zn and the macrocycle, that is, an intermediate in the metalation reaction to ZnTCNPP, which occurs upon heating to 500 K. Interestingly, the activation barrier for the successive reaction of the SAT complex to the metalated ZnTCNPP species can also be overcome by a voltage pulse applied to the STM tip.}, author = {Kuliga, Jan and De Campos Ferreirra, Rodrigo Cezar and Adhikari, Rajan and Massicot, Stephen and Lepper, Michael and Hölzel, Helen and Jux, Norbert and Marbach, Hubertus and De Siervo, Abner and Steinrück, Hans-Peter}, doi = {10.1002/cphc.202000883}, faupublication = {yes}, journal = {ChemPhysChem}, month = {Jan}, note = {CRIS-Team WoS Importer:2021-01-29}, peerreviewed = {Yes}, title = {{Metalation} of {2HTCNPP} on {Ag}(111) with {Zn}: {Evidence} for the {Sitting} atop {Complex} at {Room} {Temperature}}, year = {2021} } @article{faucris.108270184, abstract = {Complete dehydrogenation of methane is studied on model Pt catalysts by means of state-of-the-art DFT methods and by a combination of supersonic molecular beams with highresolution photoelectron spectroscopy. The DFT results predict that intermediate species like CH and CH are specially stabilized at sites located at particles edges and corners by an amount of 50-80 kJ mol . This stabilization is caused by an enhanced activity of lowcoordinated sites accompanied by their special flexibility to accommodate adsorbates. The kinetics of the complete dehydrogenation of methane is substantially modified according to the reaction energy profiles when switching from Pt(111) extended surfaces to Pt nanoparticles. The CH and CH formation steps are endothermic on Pt(111) but markedly exothermic on Pt . An important decrease of the reaction barriers is observed in the latter case with values of approximately 60 kJmol for first C - H bond scission and 40 kJ mol for methyl decomposition. DFT predictions are experimentally confirmed by methane decomposition on Pt nanoparticles supported on an ordered CeO film on Cu(111). It is shown that CH generated on the Pt nanoparticles undergoes spontaneous dehydrogenation at 100 K. This is in sharp contrast to previous results on Pt single-crystal surfaces in which CH was stable up to much higher temperatures. This result underlines the critical role of particle edge sites in methane activation and dehydrogenation. &copy; 2010 Wiley-VCH Verlag GmbH &amp; Co. KGaA, Weinheim.}, author = {Vines, Francesc and Lykhach, Yaroslava and Staudt, Thorsten and Lorenz, Michael Peter Andreas and Papp, Christian and Steinrück, Hans-Peter and Libuda, Jörg and Neyman, Konstantin and Görling, Andreas}, doi = {10.1002/chem.201000296}, faupublication = {yes}, journal = {Chemistry - A European Journal}, pages = {6530-6539}, peerreviewed = {Yes}, title = {{Methane} activation by platinum: {Critical} role of edge and corner sites of metal nanoparticles}, volume = {16}, year = {2010} } @article{faucris.107832164, abstract = {[(Benzene)(2-methyl-1,3-cyclohexadiene)Ru(0)] (1), [(1,3-cyclohexadiene) (toluene)Ru(0)] (2), and [(methyl-cyclohexadiene)(toluene)Ru(0)] (3, mixture of isomers) have been prepared and tested as new metal organic ruthenium precursor complexes for chemical vapor deposition (MOCVD) with favorable properties. 1 is a low-melting precursor complex (mp = 29 &deg;C) and the isomeric mixture 3 forms a liquid at room temperature. X-ray diffraction studies of single crystals of complexes 1 and 2 are characteristic for true Ru(0) &pi;-complexes without molecular structure peculiarities or significant intermolecular interactions in the solid state, which could hinder undecomposed evaporation. Differential thermal analysis (DTA), differential scanning calorimetry (DSC) and vapor pressure data qualify the compounds as almost ideal MOCVD precursors. Thin ruthenium films have been deposited successfully on silicon wafers and substrate temperatures between 200 and 450 &deg;C in inert gas atmospheres. Film growth and properties were evaluated by scanning electron microscopy (SEM), atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), and four-point probe conductivity measurements. All films consist of polycrystalline metallic ruthenium with a low surface roughness. &copy; The Royal Society of Chemistry 2011.}, author = {Jipa, Ilona and Danova, Katia and Popovska, Nadejda and Siddiqi, M. Aslam and Siddiqui, Rehan A. and Atakan, B. and Cremer, Till and Maier, Florian and Marbach, Hubertus and Steinrück, Hans-Peter and Heinemann, Frank Wilhelm and Zenneck, Ulrich}, doi = {10.1039/c0jm02652b}, faupublication = {yes}, journal = {Journal of Materials Chemistry}, pages = {3014-3024}, peerreviewed = {Yes}, title = {{Methylated} [(arene)(1,3-cyclohexadiene){Ru}(0)] complexes as low-melting {MOCVD} precursor complexes with a controlled follow-up chemistry of the ligands}, volume = {21}, year = {2011} } @article{faucris.121302764, abstract = {[(Benzene)(2-methyl-1,3-butadiene)Ru] (1), [(benzene)(2,3- dimethyl-1,3-butadiene)Ru] (2), and [(2,3-dimethyl-1,3-butadiene) (toluene)Ru] (3) are prepared and tested as new metal-organic (MO) ruthenium precursor complexes with favorable deposition properties for the CVD of thin ruthenium films. X-ray diffraction (XRD) studies of single crystals of the complexes are characteristic for true Ru &pi;-complexes without molecular structure peculiarities or significant intermolecular interactions in the solid state, which can hinder undecomposed evaporation. Differential thermal analysis (DTA) and vapor pressure data qualify the compounds as almost ideal MOCVD precursors. Thin ruthenium films are deposited successfully on silicon wafers at substrate temperatures between 200 and 400&deg;C in a nitrogen gas atmosphere. X-ray photoelectron spectroscopy (XPS), four-point probe conductivity measurements, and atomic force microscopy (AFM) are used to characterize the films. All films consist of polycrystalline metallic ruthenium with a low surface roughness. &copy; 2011 WILEY-VCH Verlag GmbH &amp; Co. KGaA, Weinheim.}, author = {Jipa, Ilona and Siddiqi, M. Aslam and Siddiqui, Rehan A. and Atakan, Burak and Marbach, Hubertus and Cremer, Till and Maier, Florian and Steinrück, Hans-Peter and Danova, Katia and Popovska, Nadejda and Heinemann, Frank Wilhelm and Zenneck, Ulrich}, doi = {10.1002/cvde.201006853}, faupublication = {yes}, journal = {Chemical Vapor Deposition}, pages = {15-21}, peerreviewed = {Yes}, title = {{Methylated} [(benzene)(1,3-butadiene){Ru0}] derivatives as novel {MOCVD} precursors with favorable properties}, volume = {17}, year = {2011} } @article{faucris.120341144, abstract = {Microscopic evidence of the in situ complexation of Fe-porphyrins is presented. The figure shows the sub-molecular resolved scanning tunneling microscopy images which document the metalation of 2H-TPP (central cavity; TPP: tetraphenylporphyrin) with evaporated iron (protrusions are identified as Fe-TPP). This promising technique enables future surface science investigations of clean iron porphyrin films under ultrahigh vacuum conditions. &copy; 2007 Wiley-VCH Verlag GmbH &amp; Co. KGaA.}, author = {Buchner, Florian and Schwald, Veronika and Comanici, Karmen and Steinrück, Hans-Peter and Marbach, Hubertus}, doi = {10.1002/cphc.200600698}, faupublication = {yes}, journal = {ChemPhysChem}, pages = {241-243}, peerreviewed = {Yes}, title = {{Microscopic} evidence of the metalation of a free-base porphyrin monolayer with iron}, volume = {8}, year = {2007} } @article{faucris.113262424, abstract = {Ceria-based supported noble-metal catalysts release oxygen, which may help to reduce the formation of carbonaceous residues, for example during hydrocarbon reforming. To gain insight into the microscopic origins of these effects, a model study is performed under ultrahigh-vacuum conditions using single-crystal-based supported model catalysts. The model systems are based on ordered CeO (111) films on Cu(111), on which Pt nanoparticles are grown by physical vapor deposition. The growth and structure of the surfaces are characterized by means of scanning tunneling microscopy, and the electronic structure and reactivity are probed by X-ray photoelectron spectroscopy. Specifically, it is shown that the fully oxidized CeO thin films undergo slight reduction upon Pt deposition (CeO ). This effect is enhanced upon annealing (CeO ), thus indicating facile oxygen release and reverse spillover. The model system is structurally stable up to temperatures exceeding 700 K. The activation of methane is investigated using high-kinetic-energy CH (0.83 eV), generated by a supersonic molecular beam. It is shown that dehydrogenation occurs under rapid formation of CH or C species without detectable amounts of CH being formed, even at low temperatures (100 K). The released hydrogen spills over to the CeO support, which leads to the formation of OH groups. At 200 K and above, the OH groups start to decompose leaving additional Ce centers behind (CeO ). At up to 700 K, carbon deposits are quantitatively removed by reaction with oxygen, which is supplied by reverse spillover from the CeO film, thus leading to substantial reduction of the support (~CeO ). &copy; 2010 Wiley-VCH Verlag GmbH&amp; Co. KGaA, Weinheim.}, author = {Lykhach, Yaroslava and Staudt, Thorsten and Lorenz, Michael Peter Andreas and Streber, Regine and Bayer, Andreas and Steinrück, Hans-Peter and Libuda, Jörg}, doi = {10.1002/cphc.200900673}, faupublication = {yes}, journal = {ChemPhysChem}, keywords = {cerium oxide;heterogeneous catalysis;methane dehydrogenation;supported catalysts;platinum}, pages = {1496-1504}, peerreviewed = {Yes}, title = {{Microscopic} insights into methane activation and related processes on {Pt}/{Ceria} model catalysts}, volume = {11}, year = {2010} } @article{faucris.113295644, abstract = {We review systematic experimental and theoretical efforts that explored formation, structure and reactivity of PdZn catalysts for methanol steam reforming, a material recently proposed to be superior to the industrially used Cu based catalysts. Experimentally, ordered surface alloys with a Pd: Zn ratio of &sim;1: 1 were prepared by deposition of thin Zn layers on a Pd(111) surface and characterized by photoelectron spectroscopy and low-energy electron diffraction. The valence band spectrum of the PdZn alloy resembles closely the spectrum of Cu(111), in good agreement with the calculated density of states for a PdZn alloy of 1: 1 stoichiometry. Among the issues studied with the help of density functional calculations are surface structure and stability of PdZn alloys and effects of Zn segregation in them, and the nature of the most likely water-related surface species present under the conditions of methanol steam reforming. Furthermore, a series of elementary reactions starting with the decomposition of methoxide, CH O, along both C-H and C-O bond scission channels, on various surfaces of the 1: 1 PdZn alloy [planar (111), (100) and stepped (221)] were quantified in detail thermodynamically and kinetically in comparison with the corresponding reactions on the surfaces Pd(111) and Cu(111). The overall surface reactivity of PdZn alloy was found to be similar to that of metallic Cu. Reactive methanol adsorption was also investigated by in situ X-ray photoelectron spectroscopy for pressures between 3 &times; 10 and 0.3 mbar. &copy; the Owner Societies.}, author = {Neyman, Konstantin and Lim, Kok Hwa and Chen, Zhao-Xu and Moskaleva, Lyudmila V. and Bayer, Andreas and Reindl, Armin and Borgmann, Dieter and Denecke, Reinhard and Steinrück, Hans-Peter and Rösch, Notker}, doi = {10.1039/b700548b}, faupublication = {yes}, journal = {Physical Chemistry Chemical Physics}, pages = {3470-3482}, peerreviewed = {Yes}, title = {{Microscopic} models of {PdZn} alloy catalysts: {Structure} and reactivity in methanol decomposition}, volume = {9}, year = {2007} } @article{faucris.108479404, abstract = {The boundary-layer flow over a horizontal plate is considered. In case that the heat transfer is limited to the leading edge of the plate two similarity solutions exist, if the buoyancy parameter is above a critical value. By an asymptotic expansion with respect to buoyancy parameters near the critical value it is shown that steady-state (non-similar) solutions connecting both similarity solutions exist. Finally a slowly varying transient solution is constructed. The downstream behavior of the perturbation determines which steady flow will be attained. © 1995.}, author = {Steinrück, Hans-Peter}, journal = {Fluid Dynamics Research}, pages = {113-127}, peerreviewed = {Yes}, title = {{Mixed} convection over a horizontal plate: self-similar and connecting boundary-layer flows}, url = {https://www.scopus.com/record/display.uri?eid=2-s2.0-0029240043&origin=inward}, volume = {15}, year = {1995} } @article{faucris.114140664, abstract = {Liquid organic hydrogen carriers (LOHC) are compounds that enable chemical energy storage through reversible hydrogenation. They are considered a promising technology to decouple energy production and consumption by combining high-energy densities with easy handling. A prominent LOHC is N-ethylcarbazole (NEC), which is reversibly hydrogenated to dodecahydro-N-ethylcarbazole (H -NEC). We studied the reaction of H-NEC on Pt(111) under ultrahigh vacuum (UHV) conditions by applying infrared reflection-absorption spectroscopy, synchrotron radiation-based high resolution X-ray photoelectron spectroscopy, and temperature-programmed molecular beam methods. We show that molecular adsorption of H-NEC on Pt(111) occurs at temperatures between 173 and 223 K, followed by initial C-H bond activation in direct proximity to the N atom. As the first stable dehydrogenation product, we identify octahydro-N-ethylcarbazole (H -NEC). Dehydrogenation to H-NEC occurs slowly between 223 and 273 K and much faster above 273 K. Stepwise dehydrogenation to NEC proceeds while heating to 380 K. An undesired side reaction, C-N bond scission, was observed above 390 K. H-NEC and H-carbazole are the dominant products desorbing from the surface. Desorption occurs at higher temperatures than H-NEC formation. We show that desorption and dehydrogenation activity are directly linked to the number of adsorption sites being blocked by reaction intermediates. &copy; 2014 American Chemical Society.}, author = {Amende, Maximilian and Gleichweit, Christoph and Werner, Kristin and Schernich, Stefan and Zhao, Wei and Lorenz, Michael Peter Andreas and Höfert, Oliver and Papp, Christian and Koch, Marcus and Wasserscheid, Peter and Laurin, Mathias and Steinrück, Hans-Peter and Libuda, Jörg}, doi = {10.1021/cs400946x}, faupublication = {yes}, journal = {ACS Catalysis}, pages = {657-665}, peerreviewed = {Yes}, title = {{Model} catalytic studies of liquid organic hydrogen carriers: {Dehydrogenation} and decomposition mechanisms of dodecahydro-n-ethylcarbazole on pt(111)}, volume = {4}, year = {2014} } @article{faucris.245899382, abstract = {N-heterocycles belong to the class of so-called liquid organic hydrogen carriers (LOHCs), which have been identified as suitable materials for chemical hydrogen storage due to favorable hydrogen storage capacity and reaction kinetics. In this contribution, we focus on the dehydrogenation reaction of hydrogen-rich octahydroindole, its dehydrogenation intermediate indoline, and hydrogen-lean indole. Octahydroindole has a hydrogen storage capacity of 6.4 wt %, and indoline has 1.7 wt %. We investigated the mechanism of the temperature-induced dehydrogenation of the three compounds after adsorption on Ni(111) at low temperatures. Nickel is attractive as an effective and low-priced dehydrogenation catalyst, which potentially could replace more expensive Pt and Pd in industrial applications. We compare the obtained results with our previous work on Pt(111) for the same LOHC system and for N-ethylcarbazole/H-12-N-ethylcarbazole. A comprehensive understanding of the reaction mechanism was obtained by combining high-resolution X-ray photoelectron spectroscopy with temperature-programmed desorption lab experiments. For all three compounds, we find dehydrogenation at the nitrogen atom above 270 K (indole, >= 130 K; indoline, >240 K; octahydroindole, >270 K). For indoline and octahydroindole, we observe simultaneous dehydrogenation at the carbon atoms, resulting in an indolide surface species. For octahydroindole, small amounts of side products and decomposition products are observed throughout the reaction pathway. Above 380 K, the indolide species decomposes into fragments for all three compounds.}, author = {Steinhauer, Johann and Bachmann, Philipp and Freiberger, Marie and Bauer, Udo and Steinrück, Hans-Peter and Papp, Christian}, doi = {10.1021/acs.jpcc.0c06988}, faupublication = {yes}, journal = {Journal of Physical Chemistry C}, note = {CRIS-Team WoS Importer:2020-11-27}, pages = {22559-22567}, peerreviewed = {Yes}, title = {{Model} {Catalytic} {Studies} of {Liquid} {Organic} {Hydrogen} {Carriers}: {Indole}/{Indoline}/{Octahydroindole} on {Ni}(111)}, volume = {124}, year = {2020} } @article{faucris.119846144, abstract = {Indole derivatives were recently proposed as potential liquid organic hydrogen carriers (LOHC) for storage of renewable energies. In this work, we have investigated the adsorption, dehydrogenation and degradation mechanisms in the indole/indoline/octahydroindole system on Pt(111). We have combined infrared reflection absorption spectroscopy (IRAS), X-ray photoelectron spectroscopy (XPS) and DFT calculations. Indole multilayers show a crystallization transition at 200 K, in which the molecules adopt a strongly tilted orientation, before the multilayer desorbs at 220 K. For indoline, a less pronounced restructuring transition occurs at 150 K and multilayer desorption is observed at 200 K. Octahydroindole multilayers desorb already at 185 K, without any indication for restructuring. Adsorbed monolayers of all three compounds are stable up to room temperature and undergo deprotonation at the NH bond above 300 K. For indoline, the reaction is followed by partial dehydrogenation at the 5-membered ring, leading to the formation of a flat-lying di-sigma-indolide in the temperature range from 330-390 K. Noteworthy, the same surface intermediate is formed from indole. In contrast, the reaction of octahydroindole with Pt(111) leads to the formation of a different intermediate, which originates from partial dehydrogenation of the 6-membered ring. Above 390 K, all three compounds again form the same strongly dehydrogenated and partially decomposed surface species.}, author = {Schwarz, Matthias and Bachmann, Philipp and Nascimento Silva, Thais and Mohr, Susanne and Scheuermeyer, Marlene and Späth, Florian and Bauer, Udo and Düll, Fabian and Steinhauer, Johann and Hohner, Chantal and Döpper, Tibor and Noei, Heshmat and Stierle, Andreas and Papp, Christian and Steinrück, Hans-Peter and Wasserscheid, Peter and Görling, Andreas and Libuda, Jörg}, doi = {10.1002/chem.201702333}, faupublication = {yes}, journal = {Chemistry - A European Journal}, keywords = {density functional theory;infrared reflection absorption spectroscopy;liquid organic hydrogen carrier;octahydroindole;X-ray photoelectron spectroscopy}, pages = {14806-14818}, peerreviewed = {Yes}, title = {{Model} {Catalytic} {Studies} of {Novel} {Liquid} {Organic} {Hydrogen} {Carriers}: {Indole}, {Indoline} and {Octahydroindole} on {Pt}(111)}, volume = {23}, year = {2017} } @article{faucris.258181467, abstract = {N-heterocyclic compounds such as octahydroindole and dodecahydro-N-ethylcarbazole have been proposed as suitable liquid organic hydrogen carriers for chemical hydrogen storage. Following these studies, we focused on hydrogen-rich 2,2′-bipiperidine with a hydrogen storage capacity of 7.1 wt % and hydrogen-lean 2,2′-bipyridine. Both were adsorbed on Ni(111), and the temperature-induced reaction mechanism and decomposition were studied. The reaction was investigated using synchrotron-based XPS, NEXAFS, and TPD experiments. Upon adsorption, the formation of a flat-lying chemisorbed layer is observed. Above 370 K, 2,2′-bipyridine is dehydrogenated in the α-position to the nitrogen atoms to form an α-2,2′-bipyridyl species with a tilted adsorption geometry. The hydrogen-rich 2,2′-bipiperidine is partially dehydrogenated above 180 K and deprotonated at the nitrogen atoms above 250 K. Above 320 K, α-2,2′-bipyridyl is formed, which is accompanied by a byproduct that is partially dehydrogenated at the carbon atoms. Above 400 K, we observe the decomposition of the α-2,2′-bipyridyl species. }, author = {Steinhauer, Johann and Bachmann, Philipp and Bauer, Udo and Düll, Fabian and Steinrück, Hans-Peter and Papp, Christian}, doi = {10.1021/acs.jpcc.1c00726}, faupublication = {yes}, journal = {Journal of Physical Chemistry C}, note = {CRIS-Team Scopus Importer:2021-05-14}, peerreviewed = {Yes}, title = {{Model} {Catalytic} {Studies} of the {LOHC} {System} 2,2′-{Bipiperidine}/2,2′-{Bipyridine} on {Ni}(111)}, year = {2021} } @article{faucris.108299224, abstract = {We have studied the reaction of NO with BaO nanoparticles supported on an ordered AlO thin film on NiAl (110). Combining chemical analysis by X-ray photoelectron spectroscopy (XPS) and vibrational spectroscopy by infrared reflection absorption spectroscopy (IRAS), performed in combination with molecular beam (MB) techniques, the sequence of appearance of various nitrogen-oxo surface intermediates and their spectral properties are identified. The initial intermediates at 300 K are surface nitrites (NO), which are preferentially oriented parallel to the surface. Whereas formation of nitrites is rapid even at 300 K, conversion of nitrites into surface nitrates (NO) occurs at a very low rate. After surface nitrate formation, no further reaction is observed. At higher temperature (500 K), conversion into surface nitrates is more facile and is followed by formation of ionic nitrates. All three nitrogen-oxo species can be clearly identified via their characteristic vibrational spectra. No spectroscopic evidence for the formation of other NO-derived surface species is found under the reaction conditions applied in this study. The results suggest that (i) conversion of the surface nitrite into the surface nitrate and (ii) formation of the ionic nitrate are the rate-controlling steps in the storage process. &copy;2008 American Chemical Society.}, author = {Desikusumastuti, Aine and Happel, Markus and Dumbuya, K. and Staudt, Thorsten and Laurin, Mathias and Gottfried, Michael and Steinrück, Hans-Peter and Libuda, Jörg}, doi = {10.1021/jp710994d}, faupublication = {yes}, journal = {Journal of Physical Chemistry C}, pages = {6477-6486}, peerreviewed = {Yes}, title = {{Modeling} {NOx} storage materials: {On} the formation of surface nitrites and nitrates and their identification by vibrational spectroscopy}, volume = {112}, year = {2008} } @article{faucris.108286024, abstract = {We study the modification of the growth behaviour of iron on Ag(l11) by preadsorbed monolayers of 2H-phthalocyanine (2HPc) and 2H-tetraphenylporphyrin (2HTPP) by scanning tunneling microscopy, upon Fe deposition in ultra-high vacuum at room temperature. The growth of iron on clean Ag(111) follows the scheme expected from reports of similar systems: For low coverages (up to-0.3 ML) an almost exclusive agglomeration of iron clusters at step edges occurs, which continue to grow in a dendritic fashion at higher coverages. Upon deposition onto Ag(l11) precovered with monolayers of 2HTPP and 2HPc, at coverages up to 0.037 ML no growth of Fe islands but complete metalation, i.e., incorporation of the Fe atoms in the macrocyle of the preadsorbed molecules is found. For higher amounts of deposited Fe (0.037 &lt; 0 &lt; 0.30 ML), the formation of Fe islands is observed, which occurs differently for 2HPC and 2HTPP. While on 2HTPP two-dimensional islands are formed presumably underneath a FeTPP monolayer, for 2HPc the Fe growth is dominated by the formation of small 3D clusters within a FePc monolayer. At 0 = 2.0 ML, both systems exhibit small three dimensional Fe islands. These results are discussed considering different aspects like the molecular conformation of FeTPP and FePc on Ag(111) and the diffusional properties of Fe on the clean and modified substrate. &copy; by Oldenbourg Wissenschaftsverlag.}, author = {Buchner, Florian and Kellner, Ina and Steinrück, Hans-Peter and Marbach, Hubertus}, doi = {10.1524/zpch.2009.6028}, faupublication = {yes}, journal = {Zeitschrift für Physikalische Chemie-International Journal of Research in Physical Chemistry & Chemical Physics}, pages = {131-144}, peerreviewed = {Yes}, title = {{Modification} of the growth of iron on {Ag}(111) by predeposited organic monolayers}, volume = {223}, year = {2009} } @article{faucris.277136064, abstract = {The sequentialverticalpolyfunctionalizationof 2D addend-patternedgrapheneis still elusive.Here,we reporta practicalrealizationof this goalvia a “molecularbuildingblocks”approach,whichis basedon a combinationof alithography-assistedreductivefunctionalizationapproachanda post-functionalizationstepto sequentiallyandcontrollablylink the molecularbuildingblocksethylpyridine,cis-dichlorobis(2,2’-bipyridyl)ruthenium,and triphenyl-phosphine(4-methylbenzenethiol,respectively)on selectedlatticeregionsof a graphenematrix.The assembled2Dhetero-architecturesare unambiguouslycharacterizedby variousspectroscopicand microscopicmeasurements,revealingthe stepwisestackingof the molecularbuildingblockson the graphenesurface.Our methodovercomesthe currentlimitationof a one-layer-onlybindingto the graphenesurfaceand opensthe doorfor a verticalgrowthin the z-directio}, author = {Wei, Tao and Liu, Xin and Kohring, Malte and Al-Fogra, Sabrin and Moritz, Michael and Hemmeter, Daniel and Paap, Ulrike and Papp, Christian and Steinrück, Hans-Peter and Bachmann, Julien and Weber, Heiko B. and Hauke, Frank and Hirsch, Andreas}, doi = {10.1002/anie.202201169}, faupublication = {yes}, journal = {Angewandte Chemie International Edition}, peerreviewed = {Yes}, title = {{Molecular} {Stacking} on {Graphene}}, url = {https://onlinelibrary.wiley.com/doi/epdf/10.1002/anie.202201169}, year = {2022} } @article{faucris.119122784, abstract = {There are strings attached: After linking the reacting groups to head groups of ionic liquids to drastically lower the vapour pressures of the reactants, ordinary liquid-phase organic reactions can be monitored by in situ X-ray photoelectron spectroscopy. This approach is demonstrated for the nucleophilic substitution of an alkyl amine and an alkyl chloride moiety, which are attached to the cation and anion of ionic liquids, respectively. Copyright &copy; 2012 WILEY-VCH Verlag GmbH &amp; Co. KGaA, Weinheim.}, author = {Kolbeck, Claudia and Niedermaier, Inga and Taccardi, Nicola and Schulz, Peter and Maier, Florian and Wasserscheid, Peter and Steinrück, Hans-Peter}, doi = {10.1002/anie.201107402}, faupublication = {yes}, journal = {Angewandte Chemie International Edition}, pages = {2610-2613}, peerreviewed = {Yes}, title = {{Monitoring} of liquid-phase organic reactions by photoelectron spectroscopy}, volume = {51}, year = {2012} } @article{faucris.249335206, abstract = {Porphyrins are key elements in organic-inorganic hybrid systems for a wide range of applications. Understanding their interaction with the substrate gives a handle on structural and electronic device properties. Here we investigate a single transition-metal porphyrin, namely Co(ii)-tetraphenylporphyrin (CoTPP), on the MgO(100) surface and the effect of multilayer film formation within hybrid density-functional theory and many-body perturbation theory. We focus on the relevant adsorption sites, simulate their photoemission spectra as a key fingerprint and compare with experiments on MgO(100) films on Ag(100). While we find only weak interaction between the cobalt centre and terrace sites on the MgO(100) surface, a strong interaction manifests itself with the low-coordinated sites. This leads to distinct features in both the valence and core-level regions of the electronic structure, as observed in the ultraviolet and X-ray photoemission spectra, corroborated by simulated spectra and calculated cobalt core-level shifts. Our work thus demonstrates the relevance of morphology-related low-coordinated sites and their properties in the adsorption of CoTPP on the MgO(100) surface.}, author = {Ninova, Silviya and Malcıoğlu, Osman Barış and Auburger, Philipp and Franke, Matthias and Lytken, Ole and Steinrück, Hans-Peter and Bockstedte, Michel}, doi = {10.1039/d0cp04859c}, faupublication = {yes}, journal = {Physical Chemistry Chemical Physics}, month = {Jan}, note = {CRIS-Team Scopus Importer:2021-02-12}, pages = {2105-2116}, peerreviewed = {Yes}, title = {{Morphology} dependent interaction between {Co}(ii)-tetraphenylporphyrin and the {MgO}(100) surface}, volume = {23}, year = {2021} } @article{faucris.108480284, abstract = {Electron energy loss spectra in the reflection geometry have been measured for potassium and sodium layers on Ru(001) for coverages ranging from N = 1 up to 16-20 layers. The experimental conditions (primary energy, angle-of-incidence) allowed excitation of multiple surface plasmons. For all systems, energy and damping of the surface plasmons together with the integral probability for surface plasmon excitation have been determined. For the variation of these parameters with alkali layer thickness, two coverage regimes can be distinguished that are correlated to different types of excitations. For N &le; 1 one-electron excitations are very important; for N &ge; 2 a collective response (well-defined surface plasmon excitations) takes place. The slowly decreasing energy of the surface plasmon with increasing alkali thickness to the bulk values is in qualitative agreement with both macroscopic and microscopic descriptions. The thickness dependences of the damping and the integral excitation probability indicate that one-electron contributions which are very important for N = 1 are also present for N = 2 and only slowly decrease with increasing thickness of the alkali layer. The analysis of the EELS data for N &ge; 2 shows that the excitation probability for multiple surface plasmons follows the Poisson distribution; the data are consistent with the consecutive excitation of individual surface plasmons. &copy; 1994.}, author = {Zharnikov, M. and Mehl, D. and Steinrück, Hans-Peter}, doi = {10.1016/0368-2048(94)02227-Q}, faupublication = {no}, journal = {Journal of Electron Spectroscopy and Related Phenomena}, pages = {103-116}, peerreviewed = {Yes}, title = {{Multiple} surface plasmon excitations in overlayers of {K} and {Na} on {Ru}(001)}, volume = {70}, year = {1994} } @article{faucris.109879924, abstract = {The unique properties of gold especially in low temperature CO oxidation have been ascribed to a combination of various effects. In particular, particle sizes below a few nanometers and specific particle$-$support interactions have been shown to play important roles. In contrast, recent reports revealed that monolithic nanoporous gold (npAu) prepared by leaching a less noble metal, such as Ag, out of the corresponding alloy can also exhibit a remarkably high catalytic activity for CO oxidation, even though no support is present. Therefore, it was claimed to be a pure and unsupported gold catalyst. We investigated npAu with respect to its morphology, surface composition, and catalytic properties. In particular, we studied the reaction kinetics for low temperature CO oxidation in detail, taking the mass transport limitation due to the porous structure of the material into account. Our results reveal that Ag, even if removed almost completely from the bulk, segregates to the surface, resulting in surface concentrations of up to 10 atom %. Our data suggest that this Ag plays a significant role in activating of molecular oxygen. Therefore, npAu should be considered a bimetallic catalyst rather than a pure Au catalyst.}, author = {Wittstock, Arne and Neumann, Björn and Schaefer, Andreas and Dumbuya, Karifala and Kübel, Christian and Biener, Monika M. and Zielasek, Volkmar and Steinrück, Hans-Peter and Gottfried, Michael and Biener, Jürgen and Hamza, Alex and Bäumer, Marcus}, doi = {10.1021/jp808185v}, faupublication = {yes}, journal = {Journal of Physical Chemistry C}, pages = {5593-5600}, peerreviewed = {Yes}, title = {{Nanoporous} {Au}: {An} {Unsupported} {Pure} {Gold} {Catalyst}?}, volume = {113}, year = {2009} } @article{faucris.272839001, abstract = {The deposition of nanoscaled structures with a desired shape on the intended position of the substrate material is crucial for nanomaterial applications. Electron beam-induced deposition with a highly focused beam enables achievement of high accuracy and precision in this respect. Hence, we investigated the focused-electron-beam-induced deposition of Ru-containing deposits on SiO2 and sputter-cleaned silicon in ultrahigh vacuum to achieve comparably clean and morphologically well-defined Ru nanomaterials, which is relevant especially in the field of mask repair for extreme ultraviolet lithography. The precursor Ru(CO)4I2 was held at 340-345 K, and the applied electron doses were varied from 1.56 to 9.36 C/cm2 using a focused electron beam (5 keV, 1.5 nA, and 10 nm diameter). Local Auger electron spectroscopy along with subsequent sophisticated fitting procedures not only revealed the elemental composition but also enabled determination of the thickness of the fabricated deposits. Ru contents of up to 56% can be achieved at lower electron doses; at higher doses, the Ru content decreases to 45% and simultaneously the content increases. The initially lower I content is attributed to simultaneous focused electron beam-induced etching, which is found to be competing with the deposition process. The etching is evidenced by atomic force microscopy, where the structures are observed to have negative apparent height for low electron doses. With increasing electron doses, the deposits exhibit positive apparent heights because the etching is less pronounced at higher electron doses, once the Ru surface coverage has increased. The high Ru content and difficult balance between electron-induced deposition and etching considerably expand the possibilities of engineering nanostructured materials. }, author = {Bilgilisoy, Elif and Yu, Jo Chi and Preischl, Christian and McElwee-White, Lisa and Steinrück, Hans-Peter and Marbach, Hubertus}, doi = {10.1021/acsanm.1c04481}, faupublication = {yes}, journal = {ACS Applied Nano Materials}, keywords = {Auger electron spectroscopy (AES); focused electron beam-induced deposition (FEBID); focused electron beam-induced etching (FEBIE); ruthenium nanomaterials; scanning electron microscopy (SEM)}, note = {CRIS-Team Scopus Importer:2022-04-14}, peerreviewed = {Yes}, title = {{Nanoscale} {Ruthenium}-{Containing} {Deposits} from {Ru}({CO}){4I2via} {Simultaneous} {Focused} {Electron} {Beam}-{Induced} {Deposition} and {Etching} in {Ultrahigh} {Vacuum}: {Mask} {Repair} in {Extreme} {Ultraviolet} {Lithography} and beyond}, year = {2021} } @article{faucris.264859327, abstract = {The interaction of molecules, especially hydrocarbons, at the gas/ionic liquid (IL) surface plays a crucial role in supported IL catalysis. The dynamics of this process is investigated by measuring the trapping probabilities of n-butane, iso-butane and 1-butene on a set of frozen 1-alkyl-3-methylimidazolium-based ILs [C<inf>n</inf>C<inf>1</inf>Im]X, where n=4, 8 and X⁻=Cl⁻, Br⁻, [PF<inf>6</inf>]⁻ and [Tf<inf>2</inf>N]⁻. The decrease of the initial trapping probability with increasing surface temperature is used to determine the desorption energy of the hydrocarbons at the IL surfaces. It increases with increasing alkyl chain length n and decreasing anion size for the ILs studied. We attribute these effects to different degrees of alkyl chain surface enrichment, while interactions between the adsorbate and the anion do not play a significant role. The adsorption energy also depends on the adsorbing molecule: It decreases in the order n-butane>1-butene>iso-butane, which can be explained by different dispersion interactions.}, author = {Winter, Leonhard and Bhuin, Radha Gobinda and Maier, Florian and Steinrück, Hans-Peter}, doi = {10.1002/chem.202102492}, faupublication = {yes}, journal = {Chemistry - A European Journal}, keywords = {adsorption; catalysis; gas-surface dynamics; ionic liquids; molecular beam}, note = {CRIS-Team Scopus Importer:2021-10-08}, peerreviewed = {Yes}, title = {n-{Butane}, iso-{Butane} and 1-{Butene} {Adsorption} on {Imidazolium}-{Based} {Ionic} {Liquids} {Studied} with {Molecular} {Beam} {Techniques}}, year = {2021} } @article{faucris.119488204, abstract = {Near ambient pressure X-ray photoelectron spectroscopy was applied to study the interaction of ethanol (CHCHOH) with a well-ordered CeO(1 1 1) film on Cu(1 1 1) and with a Co/CeO(1 1 1)/Cu(1 1 1) model catalyst. The oxidation state of the surface and the chemical nature of reaction intermediates were analyzed. At 300 K, the oxidation state of ceria decreased gradually with increasing ethanol pressure. At a constant pressure of 0.1 mbar, the reduction of Ce to Ce increased significantly between 320 and 600 K due to a higher mobility of oxygen or Ce centers at elevated temperatures. The main intermediate, ethoxide, was formed by dissociative adsorption of ethanol at room temperature. No coke formation was observed up to 600 K on CeO. Upon deposition of metallic cobalt, partial reduction of ceria was observed, leading to the formation of Co sites but still leaving metallic Co in the metal particles. During the reaction of ethanol with the Co/CeO(1 1 1) model catalyst, the amount of Co decreased drastically with increasing temperature, and at 600 K, the majority of Co was metallic. This process was accompanied by the severe reduction of ceria and the formation of significant carbon deposits. &copy; 2013 Elsevier Inc. All rights reserved.}, author = {Ovari, L. and Krick Calderon, Sandra and Lykhach, Yaroslava and Libuda, Jörg and Erdohelyi, A. and Papp, Christian and Kiss, J. and Steinrück, Hans-Peter}, doi = {10.1016/j.jcat.2013.07.015}, faupublication = {yes}, journal = {Journal of Catalysis}, pages = {132-139}, peerreviewed = {Yes}, title = {{Near} ambient pressure {XPS} investigation of the interaction of ethanol with {Co}/{CeO2}(1 1 1)}, volume = {307}, year = {2013} } @misc{faucris.122923724, abstract = {This invention claims new hybrid materials consisting of a solid or liq. substrate and an extremely thin film of an ultra-pure ionic liq., where the film thickness of the applied ionic liq. amts. to less than ten nanometers, preferably less then two nanometers. This extremely thin, ultra-pure film lends to the new hybrid materials with surprising and tech. interesting surface properties, different to substrate it self, different to substrate with a thicker film and different to substrate with a less pure film of the same ionic liq. This extremely thin ultra-pure film on solid or liq. substrate changes elec. cond., catalytic activity, optical, tribol., mech. properties, sensory and permeation/sepn. capability or stability against oxidn. by air of coated substrate. The ultra pure ionic liq. has a formula [A]n+[Y]n-, where A is quaternary ammonium, phosphonium, imidazolium, pyridinium, pyrazolium and triazolium cation, n= 1 or 2 and Y is an anion such as tetrafluoroborate, hexafluorophosphate, dicyanamide, tricyanomethid, tetracyano borate, halogenide or others which is applied at temp. of 30-400&deg; under high vacuum over liq. or solid substrate kept at -200-350&deg;. [on SciFinder(R)]}, author = {Cremer, Till and Maier, Florian and Steinrück, Hans-Peter and Wasserscheid, Peter}, faupublication = {yes}, keywords = {substrate pure ionic liq nanoscale surface modification hybrid material}, peerreviewed = {automatic}, title = {{New} hybrid materials consisting of solid or liquid substrate with tin ultra pure ionic liquid film.}, year = {2009} } @article{faucris.108382384, abstract = {In an effort to extend the pressure range for electron-based spectroscopies from ultrahigh vacuum into the so-called pressure gap region, we have built a new apparatus for in situ x-ray photoelectron spectroscopy up to 1 mbar. The principle of the experimental setup is based on a modified hemispherical electron energy analyzer, a modified twin anode x-ray source, and several differential-pumping stages between sample region and electron detection. The reaction gas is provided in situ either by background dosing or, as a new feature, by beam dosing, using a directed gas beam from a small tube. The latter allows for higher local pressures. The performance of the new setup is discussed, deriving normalization procedures from the analysis of the attenuation of the substrate photoemission intensity by the increasing gas phase pressure. In addition, the change of the work function due to changes in surface composition can be evaluated in situ by analyzing the binding energy shift of the gas phase core-level peaks. As a first study, measurements for the pressure dependence of CO adsorption on Pd(111) between 5&times; 10-8 and 1 mbar are presented. &copy; 2005 American Institute of Physics.}, author = {Pantförder, Jörg and Pöllmann, Silke Andrea and Zhu, Junfa and Borgmann, Dieter and Denecke, Reinhard and Steinrück, Hans-Peter}, doi = {10.1063/1.1824351}, faupublication = {yes}, journal = {Review of Scientific Instruments}, peerreviewed = {Yes}, title = {{New} setup for in situ x-ray photoelectron spectroscopy from ultrahigh vacuum to 1 mbar}, volume = {76}, year = {2005} } @article{faucris.120337624, abstract = {We studied the interaction of a highly ordered array of Co-tetraphenylporphyrin (CoTPP) with NO on Ag(111) by in situ scanning tunneling microscopy and X-ray photoelectron spectroscopy. Upon NO exposure, the initially quadratically ordered CoTPP layer reorganizes, showing a wealth of highly ordered NO+CoTPP coadsorbate phases with increasing size of the unit cell, interpreted as due to attractive lateral dipole-dipole interactions between the two species. The findings not only suggest a novel approach to control the arrangement of adsorbed porphyrins in particular but also should generally be considered in the production of functional layers from large organic molecules under ambient conditions or after exposure to small electronegative molecules. &copy; 2009 American Chemical Society.}, author = {Buchner, Florian and Seufert, Knud and Auwärter, Willi and Heim, Daniel and Barth, Johannes V. and Flechtner, Ken and Gottfried, Michael and Steinrück, Hans-Peter and Marbach, Hubertus}, doi = {10.1021/nn900399u}, faupublication = {yes}, journal = {Acs Nano}, pages = {1789-1794}, peerreviewed = {Yes}, title = {{NO}-induced reorganization of porphyrin arrays}, volume = {3}, year = {2009} } @article{faucris.120341364, abstract = {The electronic interaction between a porphyrin-coordinated Co ion and a silver surface was switched by an axial nitric oxide (NO) ligand on the Co ion. This process is reversible and was monitored with X-ray and UV-photoelectron spectroscopy (XPS and UPS). The Co-Ag interaction leads to an electron transfer from the Ag surface to the Co ion and to a new electronic state close to the Fermi level. Both effects vanish if an axial NO ligand coordinates to the Co ion, indicating that the Co-Ag interaction is suppressed. As a possible explanation, we discuss a competition, similar to the trans effect, between the two axial ligands on the Co ion: the NO molecule and the Ag surface. These findings have important implications for sensor technology and for catalysis on supported metalloporphyrins, in which the catalytic activity of the metal center is controlled by the interaction with the underlying surface. Copyright &copy; 2007 American Chemical Society.}, author = {Flechtner, Ken and Kretschmann, Andreas and Steinrück, Hans-Peter and Gottfried, Michael}, doi = {10.1021/ja0756725}, faupublication = {yes}, journal = {Journal of the American Chemical Society}, pages = {12110-12111}, peerreviewed = {Yes}, title = {{NO}-induced reversible switching of the electronic interaction between a porphyrin-coordinated cobalt ion and a silver surface}, volume = {129}, year = {2007} } @article{faucris.120347524, abstract = {The formation of one-dimensional band structures has been observed for Kr and Xe adsorbed on the reconstructed Pt(110)1&times;2 surface at submonolayer coverages: The p3/2 and p1/2 valence levels of both adsorbates exhibit significant dispersion for the [110] direction, i.e., along the densely packed substrate rows, but no dispersion is observed for [001], i.e., perpendicular to the rows. The observed k-space periodicities and tight-binding band-structure calculations imply that both Kr and Xe are adsorbed in densely packed linear chains on the reconstructed Pt(110)1&times;2 surface, with negligible interaction between neighboring rows. &copy; 1995 The American Physical Society.}, author = {Weinelt, M. and Trischberger, P. and Widdra, Wolf and Eberle, K. and Zebisch, P. and Gokhale, S. and Menzel, Dietrich and Henk, Jürgen and Feder, R. and Dröge, H. and Steinrück, Hans-Peter}, doi = {10.1103/PhysRevB.52.R17048}, faupublication = {no}, journal = {Physical Review B}, peerreviewed = {Yes}, title = {{One}-dimensional band structures: {Rare} gases on {Pt}(110)1×2}, volume = {52}, year = {1995} } @article{faucris.108486664, abstract = {The adsorption of xenon on hydrogen modified Pt(110)-(1 &times; 2) and on Pt(997) has been studied using TPD, LEED, XPS, and ARUPS. On Pt(110)-(1 &times; 2) with preadsorbed hydrogen, a single xenon species forming one-dimensional adsorbate chains in the [11̄0] direction is found. ARUPS shows well-resolved dispersion of the xenon 5p and the split Sp bands in the [11̄0] azimuth, but no dispersion in the [001] direction, in agreement with the packing density. On Pt(997) xenon decorates the close-packed steps in [11̄0] direction at low coverages. No dispersion of xenon bands is seen in ARUPS, indicating weak lateral adsorbate interaction along the chains as expected from the relatively large Xe-Xe distance of 5.6 &Aring; extracted from LEED.}, author = {Trischberger, P. and Dröge, H. and Gokhale, S. and Henk, Jürgen and Steinrück, Hans-Peter and Widdra, Wolf and Menzel, Dietrich}, doi = {10.1016/S0039-6028(96)01338-6}, faupublication = {no}, journal = {Surface Science}, pages = {155-159}, peerreviewed = {Yes}, title = {{One}-dimensional xenon band structures on hydrogen modified and stepped platinum surfaces}, year = {1997} } @article{faucris.273563253, abstract = {We investigated the adsorption, surface enrichment, ion exchange, and on-surface metathesis of ultrathin mixed IL films on Ag(111). We stepwise deposited 0.5 ML of the protic IL diethylmethylammonium trifluoromethanesulfonate ([dema][TfO]) and 1.0 ML of the aprotic IL 1-methyl-3-octylimidazolium hexafluorophosphate ([C<inf>8</inf>C<inf>1</inf>Im][PF<inf>6</inf>]) at around 90 K. Thereafter, the resulting layered frozen film was heated to 550 K, and the thermally induced phenomena were monitored in situ by angle-resolved X-ray photoelectron spectroscopy. Between 135 and 200 K, [TfO]⁻ anions at the Ag(111) surface are exchanged by [PF<inf>6</inf>]⁻ anions and enriched together with [C<inf>8</inf>C<inf>1</inf>Im]⁺ cations at the IL/vacuum interface. Upon further heating, [dema][PF<inf>6</inf>] and [OMIm][PF<inf>6</inf>] desorb selectively at ∼235 and ∼380 K, respectively. Hereby, a wetting layer of pure [C<inf>8</inf>C<inf>1</inf>Im][TfO] is formed by on-surface metathesis at the IL/metal interface, which completely desorbs at ∼480 K. For comparison, ion enrichment at the vacuum/IL interface was also studied in macroscopic IL mixtures, where no influence of the solid support is expected.}, author = {Massicot, Stephen and Sasaki, Tomoya and Lexow, Matthias and Maier, Florian and Kuwabata, Susumu and Steinrück, Hans-Peter}, doi = {10.1002/chem.202200167}, faupublication = {yes}, journal = {Chemistry - A European Journal}, keywords = {catalysis; ionic liquids; on-surface metathesis; ultra-thin films; X-ray photoelectron spectroscopy}, note = {CRIS-Team Scopus Importer:2022-04-22}, peerreviewed = {Yes}, title = {{On}-{Surface} {Metathesis} of an {Ionic} {Liquid} on {Ag}(111)}, year = {2022} } @article{faucris.272186284, abstract = {We address the adsorption of 2H-tetranaphthylporphyrin (2HTNP) and 2H-tetranaphthylbenzoporphyrin (2HTNBP) on Cu(111) and Ag(111). The difference between the two molecules is that for 2HTNBP the pyrrole groups are replaced by isoindole groups. We were interested in the resulting differences in the adsorption behavior on the two surfaces, in particular the role of the naphthyl groups. The investigations are performed with scanning tunneling microscopy at room temperature (RT) and after heating treatments (500 and 600 K). On Ag(111), 2HTNP forms a commensurable superstructure at RT, which transforms to a denser packed, non-commensurable structure upon annealing. For 2HTNBP, individual molecules are observed on Cu(111) at RT, which exhibit different mobility. In contrast, on Ag(111) the formation of ordered 2HTNBP islands occurs, which are stabilized by T-type interactions. After heating to 500 K, these islands undergo a structural change to a denser packed structure, which is stabilized by π-π stacking of neighboring naphthyl groups.}, author = {Brox, Jan and Adhikari, Rajan and Shaker, Majid and Ruppel, Michael and Jux, Norbert and Marbach, Hubertus and Jaekel, Simon and Steinrück, Hans-Peter}, doi = {10.1016/j.susc.2022.122047}, faupublication = {yes}, journal = {Surface Science}, keywords = {Commensurability; Naphthyl functionalization; Porphyrins; Self-assembly; STM}, note = {CRIS-Team Scopus Importer:2022-04-01}, peerreviewed = {Yes}, title = {{On} the adsorption of different tetranaphthylporphyrins on {Cu}(111) and {Ag}(111)}, volume = {720}, year = {2022} } @inproceedings{faucris.120381844, author = {Weinelt, M. and Zebisch, P. and Huber, W. and Pabst, M. and Birkenheuer, U. and Reichert, B. and Rösch, Notker and Steinrück, Hans-Peter}, booktitle = {Proc. Symposium on Surface Science 3S'92}, editor = {M. Alnot, J.J. Ehrhardt, C. Launois, B. Mutaftschiev, M.R. Tempère}, faupublication = {no}, pages = {276-279}, series = {Proceeding Symposium on Surface Science 3S'92 (La Plagne/Savoie)}, title = {{On} the adsorption of ethylene on {Ni}(110)}, venue = {La Plagne/Savoie}, year = {1992} } @article{faucris.247288435, abstract = {The adsorption of reactants is an elementary step in the interaction of molecules with liquid or solid surfaces. We recently reported on the trapping of n-butane on the frozen surfaces of ionic liquids (ILs), namely, 1-Alkyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide ILs ([CnC1Im][Tf2N]; n = 1, 2, 3, and 8). To study the influence of the anion, we now present results concerning the trapping of n-butane on 1-Alkyl-3-methylimidazolium hexafluorophosphate ILs ([CnC1Im][PF6]; n = 2, 4, and 8), that is, ILs with a smaller anion. The adsorption energies close to zero coverage are determined from the temperature dependence of the initial trapping probability using a novel approach. For both groups of ILs, the binding energy is dominated by the interaction of n-butane with the alkyl chain of the cation, whereas the ionic headgroups contribute only weakly. Comparing ILs with different alkyl chains at the IL cation, we find that the adsorption strength of n-butane increases with increasing length of the alkyl chain. In addition, detailed information on the new setup and the data analysis is provided. }, author = {Winter, Leonhard and Bhuin, Radha Gobinda and Lexow, Matthias and Maier, Florian and Steinrück, Hans-Peter}, doi = {10.1063/5.0028156}, faupublication = {yes}, journal = {Journal of Chemical Physics}, note = {CRIS-Team Scopus Importer:2020-12-25}, peerreviewed = {Yes}, title = {{On} the adsorption of n-butane on alkyl imidazolium ionic liquids with different anions using a new molecular beam setup}, volume = {153}, year = {2020} } @article{faucris.119846804, abstract = {The adsorption behaviour of 2H-5,10,15,20-tetraphenyltetrabenzoporphyrin (2HTPTBP) on different metal surfaces, i.e., Ag(111), Cu(111), Cu(110), and Cu(110)-(2 x 1)O was investigated by scanning tunnelling microscopy at room temperature. The adsorption of 2HTPTBP on Ag(111) leads to the formation of a well-ordered two-dimensional (2D) island structure due to the mutual stabilization through the intermolecular pi-pi stacking and T-type-like interactions of phenyl and benzene substituents of neighboring molecules. For 2HTPTBP on Cu(111), the formed 2D supramolecular structures exhibit a coverage-dependent behaviour, which can be understood from the interplay of molecule-substrate and molecule-molecule interactions. In contrast, on Cu(110) the 2HTPTBP molecules form dispersed one-dimensional (1D) molecular chains along the [1 (1) over bar0] direction of the substrate due to relatively strong attractive molecule-substrate interactions. Furthermore, we demonstrate that the reconstruction of the Cu(110) surface by oxygen atoms yields a change in dimensionality of the resulting nanostructures from 1D on Cu(110) to 2D on (2 x 1) oxygen-reconstructed Cu(110), induced by a decreased molecule-substrate interaction combined with attractive molecule-molecule interactions. This comprehensive study on these prototypical systems enables us to deepen the understanding of the particular role of the substrate concerning the adsorption behavior of organic molecules on metal surfaces and thus to tweak the ordering in functional molecular architectures.}, author = {Zhang, Liang and Lepper, Michael and Stark, Michael Werner and Menzel, Teresa and Lungerich, Dominik and Jux, Norbert and Hieringer, Wolfgang and Steinrück, Hans-Peter and Marbach, Hubertus}, doi = {10.1039/c7cp03731g}, faupublication = {yes}, journal = {Physical Chemistry Chemical Physics}, pages = {20281-20289}, peerreviewed = {Yes}, title = {{On} the critical role of the substrate: the adsorption behaviour of tetrabenzoporphyrins on different metal surfaces}, volume = {19}, year = {2017} } @article{faucris.240317116, abstract = {The impact of a reactant from the gas phase on the surface of a liquid and its transfer through this gas/liquid interface are crucial for various concepts applying ionic liquids (ILs) in catalysis. We investigated the first step of the adsorption dynamics of n-butane on a series of 1-alkyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide ILs ([C<inf>n</inf>C<inf>1</inf>Im][Tf<inf>2</inf>N]; n=1, 2, 3, 8). Using a supersonic molecular beam in ultra-high vacuum, the trapping of n-butane on the frozen ILs was determined as a function of surface temperature, between 90 and 125 K. On the C<inf>8</inf>- and C<inf>3</inf>-ILs, n-butane adsorbs at 90 K with an initial trapping probability of ≈0.89. The adsorption energy increases with increasing length of the IL alkyl chain, whereas the ionic headgroups seem to interact only weakly with n-butane. The absence of adsorption on the C<inf>1</inf>- and C<inf>2</inf>-ILs is attributed to a too short residence time on the IL surface to form nuclei for condensation even at 90 K.}, author = {Bhuin, Radha Gobinda and Winter, Leonhard and Lexow, Matthias and Maier, Florian and Steinrück, Hans-Peter}, doi = {10.1002/anie.202005991}, faupublication = {yes}, journal = {Angewandte Chemie International Edition}, keywords = {gas-surface dynamics; ionic liquids; molecular beam; n-butane; trapping and adsorption}, note = {CRIS-Team Scopus Importer:2020-07-10}, peerreviewed = {Yes}, title = {{On} the {Dynamic} {Interaction} of n-{Butane} with {Imidazolium}-{Based} {Ionic} {Liquids}}, year = {2020} } @article{faucris.120692044, abstract = {We observe and induce conformational switching of individual molecules via scanning tunneling microscopy (STM) at and close to room temperature. 2H-5,10,15,20-Tetrakis-(3,5-di-tert-butyl)-phenylporphyrin adsorbed on Cu(111) forms a peculiar supramolecular ordered phase in which the molecules arrange in alternating rows, with two distinct appearances in STM which are assigned to concave and convex intramolecular conformations. Around room temperature, frequent bidirectional conformational switching of individual molecules from concave to convex and vice versa is observed. From the temperature dependence, detailed insights into the energy barriers and entropic contributions of the switching processes are deduced. At 200 K, controlled STM tip-induced unidirectional switching is possible, yielding an information storage density of 4.9 &times; 10 bit/inch. With this contribution we demonstrate that controlled switching of individual molecules at comparably high temperatures is possible and that entropic effects can be a decisive factor in potential molecular devices at these temperatures. &copy; 2014 American Chemical Society.}, author = {Ditze, Stefanie and Stark, Michael Werner and Buchner, Florian and Aichert, André and Jux, Norbert and Luckas, Nicola and Görling, Andreas and Hieringer, Wolfgang and Hornegger, Joachim and Steinrück, Hans-Peter and Marbach, Hubertus}, doi = {10.1021/ja411884p}, faupublication = {yes}, journal = {Journal of the American Chemical Society}, month = {Jan}, pages = {1609-1616}, peerreviewed = {Yes}, title = {{On} the energetics of conformational switching of molecules at and close to room temperature}, volume = {136}, year = {2014} } @article{faucris.120411104, abstract = {The adsorption, desorption and ordering behavior of coadsorbed benzene + NO layers on Ni(111) have been studied by TPD and LEED. With increasing NO exposure dissociation of benzene upon heating is more and more suppressed and molecular benzene desorption is observed in a variety of peaks between 370 and 440 K which strongly depend on the initial benzene and NO coverages. Under certain conditions dissociation of benzene can be completely suppressed. The desorption behavior of NO is essentially unchanged as compared to NO desorption from the bare Ni(111) surface. Depending on initial benzene and NO coverage four ordered benzene + NO structures have been observed: (2 3&times;2 3)R30 &deg;, (3 &times; 3), c(2 3&times;4)rect and (2 3&times;4 3) R30 &deg;. In all cases the coadsorbed layers were disordered after adsorption at 120 K and ordering was only observed after annealing to 250 K. The observed structures can be correlated to different molecular benzene desorption peaks. The formation of the various ordered benzene + NO structures and their correlation to the TPD spectra is discussed. &copy; 1991.}, author = {Zebisch, P. and Huber, W. and Steinrück, Hans-Peter}, faupublication = {no}, journal = {Surface Science}, pages = {1-15}, peerreviewed = {Yes}, title = {{On} the formation of mixed ordered structures in the coadsorption system benzene + {NO} on {Ni}(111)}, url = {https://www.scopus.com/record/display.uri?eid=2-s2.0-0026414372&origin=inward}, volume = {258}, year = {1991} } @article{faucris.212755623, abstract = {We summarize our recent results on the oxidation of platinum surfaces, stressing the close connection between theory and experiment. The present theoretical approach is based on ab-initio quantum mechanics methods, such as density functional theory (DFT), ab-initio atomistic thermodynamics, Monte-Carlo methods and reactive molecular dynamics (RMD). Experimentally, photoelectron spectroscopy (XPS) under UHV and in-situ conditions (NAP-XPS) provides most of the discussed results. The oxidation of an extended variety of platinum surfaces is reviewed, starting from atomically flat Pt(111) over stepped surfaces to regularly shaped nanoparticles, under conditions ranging from UHV through ambient pressures up to electrochemical interfaces.}, author = {Farkas, Attila and Fantauzzi, Donato and Mueller, Jonathan E. and Zhu, Tianwei and Papp, Christian and Steinrück, Hans-Peter and Jacob, Timo}, doi = {10.1016/j.elspec.2017.06.005}, faupublication = {yes}, journal = {Journal of Electron Spectroscopy and Related Phenomena}, note = {EAM Import::2019-03-08}, peerreviewed = {Yes}, title = {{On} the platinum-oxide formation under gas-phase and electrochemical conditions}, year = {2017} } @article{faucris.120172184, abstract = {A systematic scanning tunnelling microscopy study of the self-assembly, intramolecular conformation and supramolecular ordering of different tetraphenylporphyrins (xTPP) with or without a central metal atom (x = 2H, Fe, Co) on Ag(111) at room temperature is presented. The investigation covers a wide range, i.e. the adsorption behaviour from the low sub-monolayer up to the multilayer regime is described in detail and conclusively discussed in regard to molecule-molecule and molecule-substrate interactions. At monolayer coverage the molecules self-assemble in domains with a square unit cell caused by &quot;T-type&quot; intermolecular interactions, while the orientation of the domains along the symmetry axes is determined by adsorbate-substrate interactions. Interestingly for ordered monolayers domain boundaries always separate domains of different organizational chirality but same orientation of the square unit cell. This demonstrates that in the particular system chirality obviously restricts the long range order of the supramolecular TPP assemblies. In combination with DFT calculations it is also demonstrated that the previously reported intramolecular saddle shape deformation of TPPs upon adsorption is more pronounced for metallo-TPP than for 2HTPP. &copy; 2010 the Owner Societies.}, author = {Buchner, Florian and Kellner, Ina and Hieringer, Wolfgang and Görling, Andreas and Steinrück, Hans-Peter and Marbach, Hubertus}, doi = {10.1039/c004551a}, faupublication = {yes}, journal = {Physical Chemistry Chemical Physics}, pages = {13082-13090}, peerreviewed = {Yes}, title = {{Ordering} aspects and intramolecular conformation of tetraphenylporphyrins on {Ag}(111)}, volume = {12}, year = {2010} } @article{faucris.117623704, abstract = {To elucidate the adsorption behavior and interaction mechanisms of organic linker units on oxide surfaces, we have performed a model study under ultrahigh vacuum (UHV) conditions. We apply infrared reflection absorption spectroscopy (IRAS) in combination with density-functional theory (DFT), temperature programmed desorption (TPD), and X-ray photoelectron spectroscopy (XPS). Phthalic anhydride (PM) was deposited at temperatures between 100 and 300 K by physical vapor deposition (PVD) onto an ordered MgO(100) film grown on Ag(100). At 100 K, the first monolayer adsorbs molecularly with the molecular plane aligned parallel to the surface. Subsequent growth of a multilayer film at low temperature also occurs with preferential molecular alignment parallel to the surface. At 240 K, the multilayer desorbs without decomposition. At 300 K, a mixed monolayer of chemically modified ring-opened and intact phthalic anhydride exists on the surface. The chemically modified species binds in a strongly tilted geometry via opening of the anhydride ring to form a bis-carboxylate species. This species additionally stabilizes the coadsorbed molecular PM via intermolecular interactions. Finally, surface defects and hydroxyl groups are found to increase the amount of surface bis-carboxylate at 300 K, whereas the relative amount of coadsorbed molecular PAA decreases. (C) 2015 Elsevier B.V. All rights reserved.}, author = {Mohr, Susanne and Döpper, Tibor and Xu, Tao and Tariq, Quratulain and Lytken, Ole and Laurin, Mathias and Steinrück, Hans-Peter and Görling, Andreas and Libuda, Jörg}, doi = {10.1016/jsusc.2015.06.027}, faupublication = {yes}, journal = {Surface Science}, keywords = {Phthalic anhydride;Magnesium oxide;Organic thin films;Infrared reflection absorption spectroscopy;Density-functional theory}, pages = {90-100}, peerreviewed = {Yes}, title = {{Organic} linkers on oxide surfaces: {Adsorption} and chemical bonding of phthalic anhydride on {MgO}(100)}, volume = {646}, year = {2016} } @article{faucris.121304524, abstract = {We demonstrate the application of in situ X-ray photoelectron spectroscopy (XPS) to monitor organic, liquid-phase reactions. By covalently attaching ionic head groups to the reacting organic molecules, their volatility can be reduced such that they withstand ultra high vacuum conditions. The applied method, which is new for the investigation of organic reactions, allows for following the fate of all elements present in the reaction mixtureexcept for hydrogenin a quantitative and oxidation-state-sensitive manner in one experiment. This concept is demonstrated for the alkylation of a tertiary amine attached to an imidazolium or phosphonium moiety by the anion 4-chlorobutylsulfonate ([ClC H SO ] ). In the course of the reaction, the covalently bound chlorine is converted to chloride and the amine to ammonium as reflected by the distinct shifts in the N 1s and Cl 2p binding energies. &copy; 2012 Wiley-VCH Verlag GmbH&amp; Co. KGaA, Weinheim.}, author = {Niedermaier, Inga and Kolbeck, Claudia and Taccardi, Nicola and Schulz, Peter and Li, Jing and Drewello, Thomas and Wasserscheid, Peter and Steinrück, Hans-Peter and Maier, Florian}, doi = {10.1002/cphc.201100965}, faupublication = {yes}, journal = {ChemPhysChem}, pages = {1725-1735}, peerreviewed = {Yes}, title = {{Organic} reactions in ionic liquids studied by in situ {XPS}}, volume = {13}, year = {2012} } @article{faucris.119610524, abstract = {Organic solar cells are promising in terms of full-solution-processing which enables low-cost and large-scale fabrication. While single-junction solar cells have seen a boost in power conversion efficiency (PCE), multi-junction solar cells are promising to further enhance the PCE. In all-solution-processed multi-junction solar cells, interfacial losses are often encountered between hole-transporting layer (HTL) and the active layers and therefore greatly limit the application of newly developed high-performance donor and acceptor materials in multi-junction solar cells. Here, the authors report on a systematic study of interface losses in both single-junction and multi-junction solar cells based on representative polymer donors and HTLs using electron spectroscopy and time-of-flight secondary ion mass spectrometry. It is found that a facile mixed HTL containing poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) and MoO nanoparticles successfully overcomes the interfacial losses in both single- and multi-junction solar cells based on various active layers by reducing interface protonation, promoting better energy-level alignment, and forming a dense and smooth layer. Solution-processed single-junction solar cells are demonstrated to reach the same performance as with evaporated MoO (over 7%). Multi-junction solar cells with polymers containing nitrogen atoms as the first layer and the mixed PEDOT:PSS and MoO nanoparticles as hole extraction layer reach fill factor (FF) of over 60%, and PCE of over 8%, while the identical stack with pristine PEDOT:PSS or MoO nanoparticles show FF smaller than 50% and PCE less than 5%.}, author = {Du, Xiaoyan and Lytken, Ole and Killian, Manuela and Cao, Jiamin and Stubhan, Tobias and Turbiez, Mathieu and Schmuki, Patrik and Steinrück, Hans-Peter and Ding, Liming and Fink, Rainer and Li, Ning and Brabec, Christoph}, doi = {10.1002/aenm.201601959}, faupublication = {yes}, journal = {Advanced Energy Materials}, keywords = {Interfacial losses; Organic multi-junction solar cells; Organic photovoltaics; Recombination layer; Solution-processing}, peerreviewed = {unknown}, title = {{Overcoming} {Interfacial} {Losses} in {Solution}-{Processed} {Organic} {Multi}-{Junction} {Solar} {Cells}}, year = {2016} } @article{faucris.243034850, abstract = {Supported catalytically active liquid metal solutions have been receiving increasing attention recently. We investigated the oxidation behavior of macroscopic Rh-Ga alloy droplets and Rh-Ga model catalyst nanoparticles supported on SiO2/Si(100) with low Rh content (<2.5 at. %) by x-ray photoelectron spectroscopy in ultra-high vacuum and under near-ambient pressure conditions using different photon energies and also using transmission electron microscopy. The experiments are accompanied by computational studies on the Ga oxide/Rh-Ga interface and Rh-Ga intermetallic compounds. For both Rh-Ga alloy droplets and Rh-Ga model catalyst nanoparticles, exposure to molecular oxygen leads to the formation of an oxide shell in which Rh is enriched. Transmission electron microscopy on the Rh-Ga nanoparticles confirms the formation of an ∼4 nm thick gallium oxide film containing Rh. Based on ab initio molecular dynamics and computational studies on the Ga2O3/Ga interface, it is concluded that Rh incorporation into the Ga2O3 film occurs by substituting octahedrally coordinated Ga.}, author = {Wittkämper, Haiko and Maisel, Sven and Wu, Mingjian and Frisch, Johannes and Wilks, Regan G. and Grabau, Mathias and Spiecker, Erdmann and Bär, Marcus and Görling, Andreas and Steinrück, Hans-Peter and Papp, Christian}, doi = {10.1063/5.0021647}, faupublication = {yes}, journal = {Journal of Chemical Physics}, note = {CRIS-Team Scopus Importer:2020-09-25}, pages = {104702-}, peerreviewed = {Yes}, title = {{Oxidation} induced restructuring of {Rh}-{Ga} {SCALMS} model catalyst systems}, volume = {153}, year = {2020} } @article{faucris.120318044, abstract = {In this comparative density functional theory and x-ray photoelectron spectroscopy study on the interaction of oxygen with stepped Pt(111) surfaces, we show that both the initial adsorption and oxidation occur at the steps rather than terraces. An equivalent behavior was observed for the oxide formation at higher chemical potentials, where, after the formation of a one-dimensional PtO-type oxide at the steps, similar oxide chains form on the (111) terraces, indicating the initial stages of bulk oxide formation. &copy; 2011 American Physical Society.}, author = {Bandlow, Jochen and Kaghazchi, Payam and Jacob, Timo and Papp, Christian and Tränkenschuh, Barbara and Streber, Regine and Lorenz, Michael Peter Andreas and Fuhrmann, Thomas and Denecke, R. and Steinrück, Hans-Peter}, doi = {10.1103/PhysRevB.83.174107}, faupublication = {yes}, journal = {Physical Review B}, peerreviewed = {Yes}, title = {{Oxidation} of stepped {Pt}(111) studied by x-ray photoelectron spectroscopy and density functional theory}, volume = {83}, year = {2011} } @article{faucris.221135336, abstract = {The interaction of single-layer hexagonal boron nitride (h-BN) on Ni(111) with molecular oxygen from a supersonic molecular beam led to a covalently bonded molecular oxygen species, which was identified as being between a superoxide and a peroxide. This is a rare example of an activated adsorption process leading to a molecular adsorbate. The amount of oxygen functionalization depended on the kinetic energy of the molecular beam. For a kinetic energy of 0.7 eV, an oxygen coverage of 0.4 ML was found. Near-edge X-ray adsorption fine structure (NEXAFS) spectroscopy revealed a stronger bond of h-BN to the Ni(111) substrate in the presence of the covalently bound oxygen species. Oxygen adsorption also led to a shift of the valence bands to lower binding energies. Subsequent temperature-programmed X-ray photoelectron spectroscopy revealed that the oxygen boron bonds are stable up to approximately 580 K, when desorption, and simultaneously, etching of h-BN set in. The experimental results were substantiated by density functional theory calculations, which provided insight to the adsorption geometry, the adsorption energy and the reaction pathway.}, author = {Späth, Florian and Soni, Himadriben and Steinhauer, Johann and Düll, Fabian and Bauer, Udo and Bachmann, Phillip and Hieringer, Wolfgang and Görling, Andreas and Steinrück, Hans-Peter and Papp, Christian}, doi = {10.1002/chem.201901504}, faupublication = {yes}, journal = {Chemistry - A European Journal}, keywords = {adsorption; boron nitride; density functional theory; oxygen functionalization; photoelectron spectroscopy}, note = {CRIS-Team Scopus Importer:2019-06-21}, peerreviewed = {Yes}, title = {{Oxygen} {Functionalization} of {Hexagonal} {Boron} {Nitride} on {Ni}(111)}, year = {2019} } @article{faucris.267266578, abstract = {Vanadium dioxide undergoes a metal-insulator transition from an insulating (monoclinic) to a metallic (tetragonal) phase close to room temperature, which makes it a promising functional material for many applications, e.g., as chemical sensors. Not much is known about its surface and interface properties, although these are critical in many applications. In this paper, we present an atomic-scale investigation of the tetragonal rutile VO2(110)(T) single-crystal surface and report results obtained with scanning tunneling microscopy, low-energy electron diffraction, and x-ray photoelectron spectroscopy, supported by density-functional-theory-based calculations. The surface reconstructs into an oxygen-rich (2 x 2) superstructure that coexists with small patches of the underlying unreconstructed (110)-(1 x 1) surface when the crystal is annealed >600 degrees C. The best structural model for the (2 x 2) surface termination, conceptually derived from a vanadium pentoxide (001) monolayer, consists of rings of corner-shared tetrahedra. Over a wide range of oxygen chemical potentials, this reconstruction is more stable than the unreconstructed (110) surface and models proposed in the literature.}, author = {Wagner, Margareta and Planer, Jakub and Heller, Bettina and Langer, Jens and Limbeck, Andreas and Boatner, Lynn A. and Steinrück, Hans-Peter and Redinger, Josef and Maier, Florian and Mittendorfer, Florian and Schmid, Michael and Diebold, Ulrike}, doi = {10.1103/PhysRevMaterials.5.125001}, faupublication = {yes}, journal = {Physical Review Materials}, note = {CRIS-Team WoS Importer:2021-12-17}, peerreviewed = {Yes}, title = {{Oxygen}-rich tetrahedral surface phase on high-temperature rutile {VO2}(110)({T}) single crystals}, volume = {5}, year = {2021} } @article{faucris.110438064, abstract = {This perspective analyzes the potential of X-ray photoelectron spectroscopy under ultrahigh vacuum (UHV) conditions to follow chemical reactions in ionic liquids in situ. Traditionally, only reactions occurring on solid surfaces were investigated by X-ray photoelectron spectroscopy (XPS) in situ. This was due to the high vapor pressures of common liquids or solvents, which are not compatible with the required UHV conditions. It was only recently realized that the situation is very different when studying reactions in Ionic Liquids (ILs), which have an inherently low vapor pressure, and first studies have been performed within the last years. Compared to classical spectroscopy techniques used to monitor chemical reactions, the advantage of XPS is that through the analysis of their core levels all relevant elements can be quantified and their chemical state can be analyzed under well-defined (ultraclean) conditions. In this perspective, we cover six very different reactions which occur in the IL, with the IL, or at an IL/support interface, demonstrating the outstanding potential of in situ XPS to gain insights into liquid phase reactions in the near-surface region. (C) 2017 Author(s).}, author = {Maier, Florian and Niedermaier, Inga and Steinrück, Hans-Peter}, doi = {10.1063/1.4982355}, faupublication = {yes}, journal = {Journal of Chemical Physics}, peerreviewed = {Yes}, title = {{Perspective}: {Chemical} reactions in ionic liquids monitored through the gas (vacuum)/liquid interface}, volume = {146}, year = {2017} } @article{faucris.326411387, abstract = {We have studied the adsorption of phenylphosphonic acid on rutile TiO<inf>2</inf>(110)-(1 × 1) using high-resolution synchrotron-radiation photoelectron spectroscopy and near-edge X-ray absorption fine-structure spectroscopy (NEXAFS). Upon adsorption at room temperature, we observe a complex O 1s spectrum, a single P 2p multiplet and the disappearance of small polarons in the Ti 2p and valence-band regions. Upon heating to 450-500 K, the O 1s spectrum changes, an additional P 2p species appears, the polaron signals reappear even stronger and NEXAFS indicates a more flat-lying molecule. Using density functional theory (DFT), we have determined the most stable adsorption configurations on the surface. For these configurations, we have calculated the O 1s and P 2p binding-energy positions of all oxygen and phosphorus atoms, including the first three trilayers of the TiO<inf>2</inf>(110) substrate. In addition, we have used the orientations of the phenyl rings from the DFT structures to calculate the expected polar and azimuthal angular dependencies in carbon K-edge NEXAFS. This allows us to compare our calculated adsorption configurations with the experimental observations. Below 450 K, we find a singly deprotonated bidentate species to be in perfect agreement with the experimental data. Above 500 K, the desorption of water creates oxygen vacancies, and we find a mixed bidentate and rotated-tridentate adsorption structure to be in good agreement with the experimental observations.}, author = {Wolfram, Alexander and Muth, Maximilian and Köbl, Julia and Mölkner, Andreas and Mehl, Sascha and Tsud, Nataliya and Steinrück, Hans-Peter and Meyer, Bernd and Lytken, Ole}, doi = {10.1021/acs.jpcc.4c03690}, faupublication = {yes}, journal = {Journal of Physical Chemistry C}, note = {CRIS-Team Scopus Importer:2024-07-26}, peerreviewed = {Yes}, title = {{Phenylphosphonic} {Acid} on {Rutile} {TiO2}(110): {Using} {Theoretically} {Predicted} {O} 1s {Spectra} to {Identify} the {Adsorption} {Binding} {Modes}}, year = {2024} } @article{faucris.121122804, abstract = {The two valence isomers norbornadiene (NBD) and quadricyclane (QC) enable solar energy storage in a single molecule system. We present a new photoelectrochemical infrared reflection absorption spectroscopy (PEC-IRRAS) experiment, which allows monitoring of the complete energy storage and release cycle by in situ vibrational spectroscopy. Both processes were investigated, the photochemical conversion from NBD to QC using the photosensitizer 4,4&#39;-bis(dimethylamino)benzophenone (Michler&#39;s ketone, MK) and the electrochemically triggered cycloreversion from QC to NBD. Photochemical conversion was obtained with characteristic conversion times on the order of 500 ms. All experiments were performed under full potential control in a thin layer configuration with a Pt(111) working electrode. The vibrational spectra of NBD, QC, and MK were analyzed in the fingerprint region, permitting quantitative analysis of the spectroscopic data. We determined selectivities for both the photochemical conversion and the electrochemical cycloreversion and identified the critical steps that limit the reversibility of the storage cycle.}, author = {Brummel, Olaf and Waidhas, Fabian and Bauer, Udo and Wu, Yanlin and Bochmann, Sebastian and Steinrück, Hans-Peter and Papp, Christian and Bachmann, Julien and Libuda, Jörg}, doi = {10.1021/acs.jpclett.7b00995}, faupublication = {yes}, journal = {Journal of Physical Chemistry Letters}, pages = {2819-2825}, peerreviewed = {Yes}, title = {{Photochemical} {Energy} {Storage} and {Electrochemically} {Triggered} {Energy} {Release} in the {Norbornadiene}-{Quadricyclane} {System}: {UV} {Photochemistry} and {IR} {Spectroelectrochemistry} in a {Combined} {Experiment}}, volume = {8}, year = {2017} } @article{faucris.108481384, abstract = {We have measured angular distributions of Ni3p photoelectrons for clean Ni(110), and Ni3p as well as S2p and S2p photoelectrons for c(2 &times; 2)S on Ni(110) at kinetic energies below 300 eV. From the various photoelectron diffraction patterns ( = holograms) we have reconstructed real-space images using the formalism introduced by Barton and applying a Fourier filtering technique. For the clean surface, neighboring atoms in the plane of the emitter can be identified up to the fourth coordinate sphere. The maxima in the reconstructed image show deviations from the correct positions on the order of the expected resolution. In the plane above the emitter, intense artifacts are observed in the reconstructed images in addition to maxima at or close to the correct atomic positions, which hinders an unequivocal identification of substrate atoms in that spatial region. For c(2 &times; 2) S Ni(110) we are able to verify from the reconstructed images the fourfold hollow adsorption site of sulphur, with the distance above the first Ni layer of about 0.9 &Aring;. The details of the reconstructed real-space images show some differences when using the S2p or S2p photoelectrons. From the reconstructed image in the plane of the emitter (adsorbate plane) an unequivocal identification of the neighboring S atoms in the c(2 &times; 2) layer is obscured by intense artifacts. &copy; 1994.}, author = {Zharnikov, M. and Mehl, D. and Weinelt, Martin and Zebisch, P. and Steinrück, Hans-Peter}, doi = {10.1016/0039-6028(94)91192-4}, faupublication = {no}, journal = {Surface Science}, pages = {125-143}, peerreviewed = {Yes}, title = {{Photoelectron} diffraction and holography of clean and sulphur-covered {Ni}(110)}, volume = {306}, year = {1994} } @inproceedings{faucris.108685324, author = {Mehl, D. and Zharnikov, M. and Zebisch, P. and Weinelt, M. and Steinrück, Hans-Peter}, booktitle = {Symposium on Surface Science 3S'94}, editor = {T.Rosenblatt, B.Mutaftschiev}, faupublication = {no}, pages = {60-63}, publisher = {Proceeding Symposium on Surface Science}, series = {Proceeding Symposium on Surface Science 3S'94 (Les Arcs/Savoie)}, title = {{Photoelectron} diffraction and holography of clean metal surfaces}, venue = {Les Arcs/Savoie}, year = {1994} } @article{faucris.108274144, abstract = {Photoelectron spectroscopies (PES) are a class of surface analysis techniques that involve irradiating the sample in Vacuo with photons and measuring the kinetic energy of the electrons emitted. Ultrahigh vacuum (UHV) is generally required to analyze the emitted photoelectrons without interference from gas phase collisions. XPS can be used to identify and quantify the different chemical environments of the same element within a given IL. Each individual element signal is a function of the chemical environment of the atoms of interest. There are two contributions to the observed chemical shifts in XP spectra, namely initial and final state effects. Initial state effects are those that affect the charge of the atom before the photon strikes and are described by calculations of the ground state of a particular system.}, author = {Lovelock, Kevin R.J. and Villar-Garcia, Ignacio J. and Maier, Florian and Steinrück, Hans-Peter and Licence, Peter}, doi = {10.1021/cr100114t}, faupublication = {yes}, journal = {Chemical Reviews}, pages = {5158-5190}, peerreviewed = {Yes}, title = {{Photoelectron} spectroscopy of ionic liquid-based interfaces}, volume = {110}, year = {2010} } @article{faucris.113342284, abstract = {BeTe is a new material within the class of II-VI semiconductors with novel and interesting properties. It is well lattice matched to GaAs as well as ZnSe and therefore can be combined in superlattices with these materials. Using photoelectron spectroscopy we have investigated the valence-band offset (&Delta;E) of BeTe/ZnSe and BeTe/GaAs heterojunctions, grown by molecular-beam epitaxy (MBE). For the BeTe/ZnSe heterostructure with a Zn-rich interface, we measured a valence-band offset of 1.26 &plusmn; 0.15 eV and for the heterovalent BeTe/GaAs interface we determined a far smaller valence-band offset of -0.25 &plusmn; 0.15 eV. From UPS measurements for increasing layer thickness of BeTe on ZnSe we calculated the accumulation layer of BeTe with a Debye-length of 6 nm and a defect concentration of 4.10cm. &copy; 1998 Elsevier Science B.V. All rights reserved.}, author = {Nagelstraßer, M. and Dröge, H. and Fischer, F. and Litz, T. and Waag, Andreas and Landwehr, G. and Steinrück, Hans-Peter}, doi = {10.1016/S0022-0248(98)80316-3}, faupublication = {no}, journal = {Journal of Crystal Growth}, pages = {173-177}, peerreviewed = {Yes}, title = {{Photoelectron} spectroscopy of molecular-beam epitaxially grown {BeTe}/{ZnSe} and {BeTe}/{GaAs} heterostructures}, year = {1998} } @article{faucris.123736844, abstract = {Photoinduced degradation is a critical obstacle for the real application of novel semiconductors for photovoltaic applications. In this paper, the photoinduced degradation of CHNHPbI in a vacuum and air (relative humidity 40%) is analyzed by ex situ and advanced in situ technologies. Without light illumination, CHNHPbI films slowly degrade under vacuum and air within 24 hours. However, we find that CHNHPbI converts to metallic lead (Pb) when exposed to vacuum and light illumination. Further, a series of lead salts (e.g. PbO, Pb(OH) and PbCO) are formed when CHNHPbI is degraded under environmental conditions, i.e. under the combination of light, oxygen and moisture. Photoinduced degradation is found to be determined by the environmental atmosphere as CHNHPbI films remain very stable under nitrogen conditions. The results from vacuum conditions underpin that the high volatility of the organic component (CHNHI) is in conflict with reaching excellent intrinsic stability due to its role in creating ion vacancies. The degradation in air suggests that both oxygen and water contribute to the fast photodecomposition of CHNHPbI into lead salts rather than water alone. Given these basic yet fundamental understandings, the design of hydrophobic capping layers becomes one prerequisite towards long-term stable perovskite-based devices.}, author = {Tang, Xiaofeng and Brandl, Marco and May, Benjamin and Levchuk, Ievgen and Hou, Yi and Richter, Moses and Chen, Haiwei and Chen, Shi and Kahmann, Simon and Osvet, Andres and Maier, Florian and Steinrück, Hans-Peter and Hock, Rainer and Matt, Gebhard and Brabec, Christoph}, doi = {10.1039/c6ta06497c}, faupublication = {yes}, journal = {Journal of Materials Chemistry A}, keywords = {Engineering controlled terms: Lead; Perovskite; Salts; Slow light Environmental conditions; Intrinsic stability; Light illumination; Organic components; Photo-decomposition; Photoinduced degradation; Photovoltaic applications; Real applications Engineering main heading: Photodegradation}, pages = {15896-15903}, peerreviewed = {unknown}, title = {{Photoinduced} degradation of methylammonium lead triiodide perovskite semiconductors}, volume = {4}, year = {2016} } @article{faucris.108300104, abstract = {Ultrathin films of the ionic liquid (IL) 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, [EMIM][TfN], are prepared on a glass substrate by means of an in situ thermal-evaporation/condensation process under ultrahigh-vacuum conditions. By using X-ray photoelectron spectroscopy (XPS), it is demonstrated that the first layer of the IL film grows two dimensionally, followed by the three-dimensional growth of successive layers. The first molecular layer consists of a bilayer, with the [EMIM] cations in contact to the surface and the [TfN] anions at the vacuum side. The ultrathin IL films are found to be stable under ambient conditions. &copy; 2008 Wiley-VCH Verlag GmbH &amp; Co. KGaA.}, author = {Cremer, Till and Killian, Manuela and Gottfried, Michael and Paape, Natalia and Wasserscheid, Peter and Maier, Florian and Steinrück, Hans-Peter}, doi = {10.1002/cphc.200800300}, faupublication = {yes}, journal = {ChemPhysChem}, pages = {2185-2190}, peerreviewed = {Yes}, title = {{Physical} vapor deposition of [{EMIM}][{Tf2N}]: {A} new approach to the modification of surface properties with ultrathin ionic liquid films}, volume = {9}, year = {2008} } @article{faucris.210452881, abstract = {We studied the deposition of Ga onto polycrystalline Au surfaces at room temperature by X-ray photoelectron spectroscopy (XPS). We find the formation of an alloy film with an average composition of Au7Ga3 in the near surface region probed by XPS, as deduced from qualitative and quantitative analysis of the Ga 2p(3/2), Ga 3d and Au 4f signals. The formation of the Au7Ga3 alloy is reversed, and the original spectroscopic Au 4f fingerprint is restored upon exposure of the alloy to molecular oxygen at elevated pressures and elevated temperatures. We find the formation of a GaxOy film on top of the Au substrate, which goes along with a dealloying of the surface near Au7Ga3 alloy phase.}, author = {Grabau, Mathias and Steinrück, Hans-Peter and Papp, Christian}, doi = {10.1016/j.susc.2018.07.011}, faupublication = {yes}, journal = {Surface Science}, keywords = {Au;Gold;Ga;Gallium;Intermetallic compound;IMC;PVD;XPS}, pages = {254-257}, peerreviewed = {Yes}, title = {{Physical} vapor deposition of {Ga} on polycrystalline {Au} surfaces studied using {X}-ray photoelectron spectroscopy}, volume = {677}, year = {2018} } @article{faucris.323369267, abstract = {SiO<inf>x</inf>-supported liquid GaPt systems show remarkable catalytic activity and stability in lab-scale alkane dehydrogenation reactions. However, large-scale applications provide additional challenges, like the presence of catalyst poisons in the catalytic feed that strongly bind and block active sites. A common poison are sulfur traces, which tend to interact strongly with transition metals like Pt. Therefore, macroscopic GaPt alloy droplets with low Pt content (1 at. %) and nanoscopic GaPt particles were investigated during the exposure to thiophene as catalyst poison and organic sulfur source. The measurements were performed using X-ray photoelectron spectroscopy under ultrahigh vacuum and near-ambient pressure conditions. We observed the formation of a ∼2.5 nm Ga sulfide layer, in which Pt accumulates. Notably, we do not find the formation of Pt sulfides in the model systems. For higher temperatures (>650 K), the formed Ga sulfides dissolve into the liquid metallic Ga-matrix, resulting in a Ga sulfide-free gas/liquid interface. In reference measurements, it was shown that the pure Pt particles are poisoned by sulfur and Ga is not reactive toward the formation of sulfides. Pt seems to play a key role in the formation of Ga sulfides since particles only consisting of Ga show only minor sulfur deposits.}, author = {Wichmann, Christoph and Moritz, Michael and Wittkämper, Haiko and Hsieh, Tzung En and Frisch, Johannes and Bär, Marcus and Steinrück, Hans-Peter and Papp, Christian}, doi = {10.1021/acs.jpcc.4c01697}, faupublication = {yes}, journal = {Journal of Physical Chemistry C}, note = {CRIS-Team Scopus Importer:2024-06-07}, peerreviewed = {Yes}, title = {{Poisoning} {Resistance} of {Liquid} {GaPt} {Supported} {Catalytically} {Active} {Liquid} {Metal} {Solutions} {Model} {Systems}}, year = {2024} } @article{faucris.312969742, abstract = {Electrochemical proton storage plays an essential role in designing next-generation high-rate energy storage devices, e.g., aqueous batteries. Two-dimensional conjugated covalent organic frameworks (2D c-COFs) are promising electrode materials, but their competitive proton and metal-ion insertion mechanisms remain elusive, and proton storage in COFs is rarely explored. Here, we report a perinone-based poly(benzimidazobenzophenanthroline) (BBL)-ladder-type 2D c-COF for fast proton storage in both a mild aqueous Zn-ion electrolyte and strong acid. We unveil that the discharged C−O⁻ groups exhibit largely reduced basicity due to the considerable π-delocalization in perinone, thus affording the 2D c-COF a unique affinity for protons with fast kinetics. As a consequence, the 2D c-COF electrode presents an outstanding rate capability of up to 200 A g⁻¹ (over 2500 C), surpassing the state-of-the-art conjugated polymers, COFs, and metal–organic frameworks. Our work reports the first example of pure proton storage among COFs and highlights the great potential of BBL-ladder-type 2D conjugated polymers in future energy devices.}, author = {Wang, Mingchao and Wang, Gang and Naisa, Chandrasekhar and Fu, Yubin and Gali, Sai Manoj and Paasch, Silvia and Wang, Mao and Wittkämper, Haiko and Papp, Christian and Brunner, Eike and Zhou, Shengqiang and Beljonne, David and Steinrück, Hans-Peter and Dong, Renhao and Feng, Xinliang}, doi = {10.1002/anie.202310937}, faupublication = {yes}, journal = {Angewandte Chemie International Edition}, keywords = {2D Conjugated COFs; Poly(Benzimidazobenzophenanthroline); Proton Storage; Strong Acid; Zn-Ion Electrolyte}, note = {CRIS-Team Scopus Importer:2023-10-20}, peerreviewed = {Yes}, title = {{Poly}(benzimidazobenzophenanthroline)-{Ladder}-{Type} {Two}-{Dimensional} {Conjugated} {Covalent} {Organic} {Framework} for {Fast} {Proton} {Storage}**}, year = {2023} } @article{faucris.121502964, abstract = {The molecular arrangement and the internal conformation of Co(II)-5,10,15,20-tetrakis-(3,5-di-tert-butylphenyl)-porphyrin (Co(II)-TTBPP) on Ag(111) was studied by scanning tunneling microscopy (STM) under ultrahigh vacuum (UHV) conditions. Interestingly, four different molecular arrangements were found using different routes to prepare the porphyrin films. After the preparation of a film with a coverage slightly below one monolayer by thermal sublimation, three clearly distinguishable molecular arrangements could be observed. Alternatively, a monolayer was prepared by deposition of a multilayer followed by subsequent annealing to desorb the excess multilayer molecules. Thereby, an additional, very rigid herringbone structure formed via a thermally activated process, covering most of the surface. The four ordered phases go along with different conformations of the individual molecules. On the basis of STM images with submolecular resolution, models for the lateral arrangements of the different polymorphs including the internal conformation of the individual molecules are proposed. Thereby, as an extension to previous works, the rotation of the upper tert-butyl groups of Co-TTBPP was taken into account. The derived molecular arrangements in combination with the intramolecular conformations give insight into the intermolecular interactions within and the nature of the different molecular phases. &copy; 2007 American Chemical Society.}, author = {Buchner, Florian and Comanici, Karmen and Jux, Norbert and Steinrück, Hans-Peter and Marbach, Hubertus}, doi = {10.1021/jp074448z}, faupublication = {yes}, journal = {Journal of Physical Chemistry C}, pages = {13531-13538}, peerreviewed = {Yes}, title = {{Polymorphism} of porphyrin molecules on {Ag}(111) and how to weave a rigid monolayer}, volume = {111}, year = {2007} } @article{faucris.108882884, abstract = {We show that both single-crystalline and nanostructured MgO surfaces convert free-base tetraphenyl porphyrin (2HTPP) into magnesium tetraphenyl porphyrin (MgTPP) at room temperature. The reaction can be viewed as an ion exchange between the two aminic protons of the 2HTPP molecule with a Mg ion from the surface. The driving force for the reaction is the strong stability of the formed hydroxyl groups along the steps and at defects on the MgO surface. We have used an integrated characterization approach that includes UV/Vis diffuse reflectance measurements on nanostructured powders, X-ray photoelectron spectroscopic investigation of atomically clean MgO(100) single-crystalline thin films, and density functional theory (DFT) calculations on model systems. The DFT calculations demonstrate that MgTPP formation is strongly exothermic at the corners, edges and steps, but slightly endothermic on terrace sites. This agrees well with the UV/Vis diffuse reflectance, which upon adsorption of 2HTPP shows a decrease in the absorption band associated with corner and edge sites on MgO nanocube powders. Porphyrin swap shop: Spectroscopic adsorption studies on two complementary model systems, atomically clean thin MgO(100) films and MgO nanocube powders, show that low-coordinated surface cations located in corner, edge, or step regions of the MgO surfaces are subject to ion exchange between adsorbed porphyrin molecules and the oxide surface.}, author = {Schneider, Johannes and Franke, Matthias and Gurrath, Martin and Röckert, Michael and Berger, Thomas and Bernardi, Johannes and Meyer, Bernd and Steinrück, Hans-Peter and Lytken, Ole and Diwald, Oliver}, doi = {10.1002/chem.201503661}, faupublication = {yes}, journal = {Chemistry - A European Journal}, keywords = {ion exchange; metalation; nanocubes; porphyrin; surface defects}, pages = {1744-1749}, peerreviewed = {unknown}, title = {{Porphyrin} {Metalation} at {MgO} {Surfaces}: {A} {Spectroscopic} and {Quantum} {Mechanical} {Study} on {Complementary} {Model} {Systems}}, volume = {22}, year = {2016} } @article{faucris.227317393, abstract = {A new approach to investigate potential screening at the interface of ionic liquids (ILs) and charged electrodes in a two-electrode electrochemical cell by in situ X-ray photoelectron spectroscopy has been introduced. Using identical electrodes, we deduce the potential screening at the working and the counter electrodes as a function of applied voltage from the potential change of the bulk IL, as derived from corresponding core level binding energy shifts for different IL/electrode combinations. For imidazolium-based ILs and Pt electrodes, we find a significantly larger potential screening at the anode than at the cathode, which we attribute to strong attractive interactions between the imidazolium cation and Pt. In the absence of specific ion/electrode interactions, asymmetric potential screening only occurs for ILs with different cation and anion sizes as demonstrated for an imidazolium chloride IL and Au electrodes, which we assign to the different thicknesses of the electrical double layers. Our results imply that potential screening in ILs is mainly established by a single layer of counterions at the electrode.}, author = {Greco, Francesco and Shin, Sunghwan and Williams, Federico J. and Heller, Bettina and Maier, Florian and Steinrück, Hans-Peter}, doi = {10.1002/open.201900211}, faupublication = {yes}, journal = {ChemistryOpen}, note = {CRIS-Team WoS Importer:2019-10-01}, peerreviewed = {Yes}, title = {{Potential} {Screening} at {Electrode}/{Ionic} {Liquid} {Interfaces} from {In} {Situ} {X}-ray {Photoelectron} {Spectroscopy}}, year = {2019} } @article{faucris.120346204, abstract = {The dynamics of molecular chemisorption of CO on Ni(100) has been investigated using supersonic molecular beam techniques. In order to probe the role of energy accommodation and of so-called precursor states, we have determined the dependence of the molecular sticking probability and the angular scattering distribution on the translational energy and incident angle of the incoming molecules, on surface temperature, and on surface coverage. At low translational energy CO adsorption proceeds in a fashion indicative of classical precursor kinetics. However, both the temperature independence of the initial sticking probability and the form of the angular scattering distribution of non-chemisorbing molecules (obtained using modulated beam techniques) indicate that molecules that fail to chemisorb on the clean surface are directly scattered and do not become fully accommodated in a precursor state. As the translational energy of the CO molecules at normal incidence is increased from 2 to 30 kcal mol, S decreases smoothly from 0.91 to 0.5. Further, for translational energies greater than 10 kcal mol S decreases with increasing angle of incidence. This surprising result indicates that the chemisorption probability decreases as the component of incident velocity parallel to the surface increases, just as it does for the normal component, but at a larger rate. The dynamics of the accommodation process are discussed in terms of a &quot;hot&quot;, not thermalized, precursor. Increasing the translational energy of the molecule affects not only the value of the sticking probability but also the form of the variation of sticking probability with coverage and with surface temperature. We report for the first time a transition between precursor adsorption kinetics at low translational energy (2 kcal mol) to direct (Langmuirian) adsorption at high incident energy (21 kcal mol). Scattering experiments performed on a surface with saturation coverage confirm this result. &copy; 1987.}, author = {D'Evelyn, M.P. and Steinrück, Hans-Peter and Madix, R.J.}, faupublication = {no}, journal = {Surface Science}, pages = {47-76}, peerreviewed = {Yes}, title = {{Precursors} and trapping in the molecular chemisorption of {CO} on {Ni}(100)}, url = {https://www.scopus.com/record/display.uri?eid=2-s2.0-0002569441&origin=inward}, volume = {180}, year = {1987} } @article{faucris.108387004, abstract = {The direct metalation of tetraphenylporphyrin with bare metal atoms (Co and Zn) was studied with X-ray photoelectron spectroscopy, scanning tunneling microscopy, and temperature-programmed reaction measurements on ordered monolayer films of the molecules adsorbed on a Ag(111) surface. The mechanism of this novel type of surface reaction was investigated using density functional theory (DFT) calculations for the related gas-phase reactions of the unsubstituted porphyrin with the metals Fe, Co, Ni, Cu, and Zn. The reaction starts with the formation of an initial complex, in which the metal atom is coordinated by the intact unreduced porphyrin. This complex resembles the sitting-atop complex proposed for porphyrin metalation with metal ions in solution. In two subsequent steps, the pyrrolic hydrogen atoms are transferred to the metal atom, forming H , which is eventually released. The activation barriers of the H-transfer steps vary for the different metal atoms. DFT calculations suggest that metalations with Fe, Co, and Ni show two-state reactivity, while those with Cu and Zn proceed on a single potential energy surface. For metalation with Zn, we calculated a barrier of the first hydrogen transfer step of 32.6 kcal mol , in good agreement with the overall experimental activation energy of 31 kcal mol . &copy; 2007 American Chemical Society.}, author = {Shubina, Tatyana and Marbach, Hubertus and Flechtner, Ken and Kretschmann, Andreas and Jux, Norbert and Buchner, Florian and Steinrück, Hans-Peter and Clark, Timothy and Gottfried, Michael}, doi = {10.1021/ja072360t}, faupublication = {yes}, journal = {Journal of the American Chemical Society}, pages = {9476-9483}, peerreviewed = {Yes}, title = {{Principle} and mechanism of direct porphyrin metalation: {Joint} experimental and theoretical investigation}, volume = {129}, year = {2007} } @article{faucris.121282964, abstract = {A mechanistic study: In a Br&oslash;nsted acid/base reaction, gaseous triflic acid (OTfH) transfers its proton to the basic Cl anion of the ionic liquid [CCIm]Cl forming volatile HCl and the IL [CCIm][TfO]. This anion exchange reaction is monitored in the near-surface region quantitatively by X-ray photoelectron spectroscopy as a function of time (see picture; BE=binding energy). Copyright &copy; 2013 WILEY-VCH Verlag GmbH &amp; Co. KGaA, Weinheim.}, author = {Niedermaier, Inga and Taccardi, Nicola and Wasserscheid, Peter and Maier, Florian and Steinrück, Hans-Peter}, doi = {10.1002/anie.201304115}, faupublication = {yes}, journal = {Angewandte Chemie International Edition}, pages = {8904-8907}, peerreviewed = {Yes}, title = {{Probing} a gas/liquid acid-base reaction by {X}-ray photoelectron spectroscopy}, volume = {52}, year = {2013} } @article{faucris.285674663, abstract = {We report on the surface and interface tension measurements of the two ionic liquids (ILs) [C<inf>8</inf>C<inf>1</inf>Im][PF<inf>6</inf>] and [m(PEG<inf>n</inf>)<inf>2</inf>Im]I (n = 2, 4, 6) in a surface science approach. The measurements were performed in a newly developed and unique experimental setup, which allows for surface tension (ST) measurements using the pendant drop method and for contact angle measurements using the sessile drop method under the well-defined conditions of a high vacuum (from 10⁻⁷ mbar). The setup also allows for in vacuum transfer to an ultrahigh vacuum system for surface preparation and analysis, such as in angle-resolved X-ray photoelectron spectroscopy. For [C<inf>8</inf>C<inf>1</inf>Im][PF<inf>6</inf>], we observe a linear decrease in the surface tension with increasing temperature. The ST measured under high vacuum is consistently found to be larger than under ambient conditions, which is attributed to the influence of water uptake in air by the IL. For [m(PEG<inf>n</inf>)<inf>2</inf>Im]I (n = 2, 4, 6), we observe a decrease in the ST with increasing polyethylene glycol chain length in a vacuum, similar to very recent observations under 1 bar Argon. This decrease is attributed to an increasing enrichment of the PEG chains at the surface. The ST data obtained under these ultraclean conditions are essential for a fundamental understanding of the relevant parameters determining ST on the microscopic level and can serve as a benchmark for theoretical calculations, such as molecular dynamic simulations. In addition to the ST measurements, proof-of-principle data are presented for sessile drop measurements in HV, and a detailed description and characterization of the new setup is provided.}, author = {Paap, Ulrike and Kreß, Bernd and Steinrück, Hans-Peter and Maier, Florian}, doi = {10.3390/ijms232113158}, faupublication = {yes}, journal = {International Journal of Molecular Sciences}, keywords = {interface tension; ionic liquids (ILs); pendant drop; sessile drop; surface science; surface tension; vacuum}, note = {CRIS-Team Scopus Importer:2022-11-25}, peerreviewed = {Yes}, title = {{Probing} {Surface} and {Interfacial} {Tension} of {Ionic} {Liquids} in {Vacuum} with the {Pendant} {Drop} and {Sessile} {Drop} {Method}}, volume = {23}, year = {2022} } @article{faucris.121164824, abstract = {The interaction of CeO2-supported Rh, Co and bimetallic Rh-Co nanoparticles, which are active catalysts in hydrogen production via steam reforming of ethanol, a process related to renewable energy generation, was studied by X-ray diffraction (XRD), high resolution electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS) and low energy ion scattering (LEIS). Furthermore, diffuse reflectance infrared spectroscopy (DRIFTS) of adsorbed CO as a probe molecule was used to characterize the morphology of metal particles. At small loadings (0.1%), Rh is in a much dispersed state on ceria, while at higher contents (1-5%), Rh forms 2-8 nm particles. Between 473-673 K pronounced oxygen transfer from ceria to Rh is observed and at 773 K significant agglomeration of Rh occurs. On reduced ceria, XPS indicates a possible electron transfer from Rh to ceria. The formation of smaller ceria crystallites upon loading with Co was concluded from XRD and HRTEM; for 10% Co, the CeO2 particle size decreased from 27.6 to 10.7 nm. A strong dissolution of Co into ceria and a certain extent of encapsulation by ceria were deduced by XRD, XPS and LEIS. In the bimetallic system, the presence of Rh enhances the reduction of cobalt and ceria. During thermal treatments, reoxidation of Co occurs, and Rh agglomeration as well as oxygen migration from ceria to Rh are hindered in the presence of cobalt.}, author = {Varga, E. and Pusztai, P. and Ovari, L. and Oszko, A. and Erdohelyi, A. and Papp, Christian and Steinrück, Hans-Peter and Konya, Zoltan and Kiss, J.}, doi = {10.1039/c5cp03549j}, faupublication = {yes}, journal = {Physical Chemistry Chemical Physics}, month = {Jan}, pages = {27154-27166}, peerreviewed = {Yes}, title = {{Probing} the interaction of {Rh}, {Co} and bimetallic {Rh}-{Co} nanoparticles with the {CeO2} support: catalytic materials for alternative energy generation}, volume = {17}, year = {2015} } @article{faucris.243317530, abstract = {Thin-film growth of molecular systems is of interest for many applications, such as for instance organic electronics. In this study, we demonstrate how X-ray photoelectron spectroscopy (XPS) can be used to study the growth behavior of such molecular systems. In XPS, coverages are often calculated assuming a uniform thickness across a surface. This results in an error for rough films, and the magnitude of this error depends on the kinetic energy of the photoelectrons analyzed. We have used this kinetic-energy dependency to estimate the roughnesses of thin porphyrin films grown on rutile TiO<inf>2</inf>(110). We used two different molecules: cobalt (II) monocarboxyphenyl-10,15,20-triphenylporphyrin (CoMCTPP), with carboxylic-acid anchor groups, and cobalt (II) tetraphenylporphyrin (CoTPP), without anchor groups. We find CoMCTPP to grow as rough films at room temperature across the studied coverage range, whereas for CoTPP the first two layers remain smooth and even; depositing additional CoTPP results in rough films. Although, XPS is not a common technique for measuring roughness, it is fast and provides information of both roughness and thickness in one measurement.}, author = {Kataev, Elmar and Wechsler, Daniel and Williams, Federico J. and Köbl, Julia and Tsud, Natalia and Franchi, Stefano and Steinrück, Hans-Peter and Lytken, Ole}, doi = {10.1002/cphc.202000568}, faupublication = {yes}, journal = {ChemPhysChem}, keywords = {Growth; Porphyrin molecules; Thin films; X-ray photoelectron spectroscopy}, note = {CRIS-Team Scopus Importer:2020-10-02}, peerreviewed = {Yes}, title = {{Probing} the {Roughness} of {Porphyrin} {Thin} {Films} with {X}-ray {Photoelectron} {Spectroscopy}}, year = {2020} } @article{faucris.202402670, abstract = {At 298 K, the surface tension of ionic liquids (ILs) of the 1-alkyl-3-methylimidazolium bis- (trifluoromethylsulfonyl)imide series, [CnC1,Im][NTf2 ], ranges 36 from around 35 mN center dot m(-1) for [C2C1 Im][NTf2] to just below 30 mN center dot m(-1)for [C(12)C(1)Im][NTf2]. However, the decrease rate along the series is not constant: a large decrease from [C(2)C(1)Im][NTf2] to [C(8)C(1)Im][NTf2] is followed by almost constant values from [C(8)C(1)Im][NTf2] to [C(12)C(1)Im][NTf2]. Such behavior is hard to interpret from a molecular point of view without suitable information about the free-surface structure of the different ILs. In this work, we have successfully used the Langmuir principle in combination with structural data obtained from angle-resolved Xray photoelectron spectroscopy experiments and molecular dynamics simulations, to predict the correct surface tension trend along the IL series. The concepts unveiled for this particular homologous IL family can be easily extended to other systems.}, author = {Shimizu, Karina and Heller, Bettina and Maier, Florian and Steinrück, Hans-Peter and Canongia Lopes, Jose N.}, doi = {10.1021/acs.langmuir.7b04237}, faupublication = {yes}, journal = {Langmuir}, pages = {4408-4416}, peerreviewed = {Yes}, title = {{Probing} the {Surface} {Tension} of {Ionic} {Liquids} {Using} the {Langmuir} {Principle}}, volume = {34}, year = {2018} } @article{faucris.121304744, abstract = {Nitrogen doping of graphene is a suitable route to tune the electronic structure of graphene, leading to n-type conductive materials. Herein, we report a simple way to insert nitrogen atoms into graphene by low-energy nitrogen bombardment, forming nitrogen-doped graphene. The formation of nitrogen-doped graphene is investigated with high resolution X-ray photoelectron spectroscopy, allowing to determine the doping level and to identify two different carbon-nitrogen species. By application of different ion implantation energies and times, we demonstrate that a doping level of up to 0.05 monolayers is achievable and that the branching ratio of the two nitrogen species can be varied. &copy; 2012 American Chemical Society.}, author = {Zhao, Wei and Höfert, Oliver and Gotterbarm, Karin and Zhu, Junfa and Papp, Christian and Steinrück, Hans-Peter}, doi = {10.1021/jp209927m}, faupublication = {yes}, journal = {Journal of Physical Chemistry C}, pages = {5062-5066}, peerreviewed = {Yes}, title = {{Production} of nitrogen-doped graphene by low-energy nitrogen implantation}, volume = {116}, year = {2012} } @article{faucris.235885502, abstract = {Different binary mixtures of two functionalized ionic liquids (ILs), namely 1,3-di(methoxy)imidazolium hexafluorophosphate, [(MeO)<inf>2</inf>Im][PF<inf>6</inf>], and 3-methyl-1-(3,3,4,4,4-pentafluorobutyl)imidazolium hexafluorophosphate, [PFBMIm][PF<inf>6</inf>], are investigated in the liquid state by angle-resolved X-ray photoelectron spectroscopy (ARXPS). Both ILs consist of the same [PF<inf>6</inf>]⁻ anion but differ in the functionalization of the cation: [(MeO)<inf>2</inf>Im][PF<inf>6</inf>] has an oxygen atom directly bound to each nitrogen atom of the imidazolium ring whereas in [PFBMIm][PF<inf>6</inf>] the two terminal carbon atoms of the butyl chain are fully fluorinated. Due to different electronic structures of the cations of both ILs, the ARXP signals of the two cations and of the anion can be well distinguished, which allows to identify preferential chain orientation as well as enrichment and depletion effects at the surface. In the mixtures with 50, 90 and 95 mol% [(MeO)<inf>2</inf>Im][PF<inf>6</inf>], a very pronounced enrichment of the [PFBMIm]⁺ cation at the IL/vacuum interface is observed. The fluorinated chain points towards the vacuum side and thereby attenuates the signal of the [PF<inf>6</inf>]⁻ anion. Decreasing the temperature from 95 °C to close to the solidification temperatures of the mixtures leads to a more pronounced surface enrichment of the [PFBMIm]⁺ cation and of the fluorinated chain.}, author = {Heller, Bettina and Paap, Ulrike and Maier, Florian and Steinrück, Hans-Peter}, doi = {10.1016/j.molliq.2020.112783}, faupublication = {yes}, journal = {Journal of Molecular Liquids}, keywords = {Ionic liquid; Mixture; Surface enrichment; X-ray photoelectron spectroscopy}, note = {CRIS-Team Scopus Importer:2020-03-17}, peerreviewed = {Yes}, title = {{Pronounced} surface enrichment of fluorinated ionic liquids in binary mixtures with methoxy-functionalized ionic liquids}, volume = {305}, year = {2020} } @article{faucris.234391589, abstract = {We have prepared model systems for Pt-Ga supported catalytically active liquid metal solutions (SCALMS) by physical vapor deposition of Pt and Ga onto highly oriented pyrolytic graphite (HOPG). Prior to metal deposition, the HOPG support was modified by Ar+ bombardment. In this work, we focus on the stability of the Pt-Ga deposits toward agglomeration, which is a critical challenge in application. Specifically, we study the behavior of the model catalysts in ultrahigh vacuum (UHV) and under near ambient pressure (NAP) conditions at different temperatures. We use CO as a probe molecule to examine changes in the surface composition of the Pt-Ga deposits by in situ infrared reflection absorption spectroscopy (IRAS). In specific, we combine IRAS and ex situ atomic force microscopy (AFM) to study changes induced by annealing. We find that sintering effects are strongly dependent on the thickness of the deposited Pt-Ga layers. Our data suggest that particle ripening leads to a separation of the system into disperse Pt-rich and large Ga-rich particles. In the NAP regime, we performed simultaneous measurements with polarization modulation IRAS (PM-IRAS) and near ambient pressure X-ray photoelectron spectroscopy (NAP-XPS). The alloying of Pt and Ga is accompanied by a shift of Pt 4f and Ga 3d photoelectron lines to higher binding energies. Although partial oxidation of Ga is observed upon CO exposure at pressures in the millibar regime, PM-IRAS shows'adsorbed CO at a frequency typical for Pt ensembles in a Ga matrix.}, author = {Hohner, Chantal and Kettner, Miroslav and Stumm, Corinna and Blaumeiser, Dominik and Wittkämper, Haiko and Grabau, Mathias and Schwarz, Matthias and Schuschke, Christian and Lykhach, Yaroslava and Papp, Christian and Steinrück, Hans-Peter and Libuda, Jörg}, doi = {10.1021/acs.jpcc.9b10944}, faupublication = {yes}, journal = {Journal of Physical Chemistry C}, month = {Jan}, note = {CRIS-Team WoS Importer:2020-02-18}, pages = {2562-2573}, peerreviewed = {Yes}, title = {{Pt}-{Ga} {Model} {SCALMS} on {Modified} {HOPG}: {Thermal} {Behavior} and {Stability} in {UHV} and under {Near}-{Ambient} {Conditions}}, volume = {124}, year = {2020} } @article{faucris.108883544, abstract = {We investigated the adsorption and reaction of pyridine on flat Pt(111) and stepped Pt(355) surfaces via high-resolution in situ x-ray photoelectron spectroscopy. The surfaces were exposed to pyridine at temperatures between 112 and 300 K while simultaneously recording XP spectra. Subsequently, the crystals were annealed and the temperature dependencies of the N 1s and C 1s core levels were studied again in a continuous and quantitative way. Various surface species were found, namely, physisorbed, flat-lying and end-on pyridine, &alpha;-pyridyl species on the terraces and on the steps and several unidentified high temperature species. We were able to show an influence of the steps of Pt(355) by pre-adsorbing silver next to the step, which selectively suppresses the step adsorption.}, author = {Steinrück, Hans-Peter and Welke, Martin and Eilert, Andre and Denecke, Reinhard and Schoeppke, Matthias and Wöckel, Claudia}, doi = {10.1063/1.4939527}, faupublication = {yes}, journal = {Journal of Chemical Physics}, month = {Jan}, peerreviewed = {Yes}, title = {{Pyridine} on flat {Pt}(111) and stepped {Pt}(355) - {An} in situ {HRXPS} investigation of adsorption and thermal evolution}, volume = {144}, year = {2016} } @article{faucris.242712949, abstract = {We report the reversible functionalization of hexagonal boron nitride (h-BN) on Ni(111) with a molecular oxygen species and atomic hydrogen, as studied by high-resolution X-ray photoelectron spectroscopy, ultraviolet photoelectron spectroscopy, and near-edge X-ray absorption fine structure. As a first step, we prepare oxygen-functionalized h-BN by exposure to a supersonic beam of molecular oxygen. Subsequent exposure to atomic hydrogen leads to complete removal of the oxygen species and the formation of hydrogen-functionalized h-BN. In turn, this hydrogen-functionalized h-BN can be reconverted to oxygen-functionalized h-BN by exposure to the supersonic oxygen beam. This reaction occurs at a lower rate as the initial functionalization of pristine h-BN with oxygen. We further demonstrate that the core levels and valence bands of h-BN can be shifted at will between the boundaries obtained for the purely oxygen- and hydrogen-functionalized h-BN layers.}, author = {Späth, Florian and Steinhauer, Johann and Düll, Fabian and Bauer, Udo and Bachmann, Philipp and Steinrück, Hans-Peter and Papp, Christian}, doi = {10.1021/acs.jpcc.0c05299}, faupublication = {yes}, journal = {Journal of Physical Chemistry C}, note = {CRIS-Team WoS Importer:2020-09-18}, pages = {18141-18146}, peerreviewed = {Yes}, title = {{Reaction} of {Hydrogen} and {Oxygen} on h-{BN}}, volume = {124}, year = {2020} } @article{faucris.206667452, author = {Lexow, Matthias and May, Benjamin and Taccardi, Nicola and Steinrück, Hans-Peter and Maier, Florian}, doi = {10.1002/open.201800149}, faupublication = {yes}, journal = {ChemistryOpen}, keywords = {ionic liquids; corrosion; photoelectron spectroscopy; metal dissolution; surface analysis}, peerreviewed = {unknown}, title = {{Reactions} of a {Polyhalide} {Ionic} {Liquid} with {Copper}, {Silver}, and {Gold}}, year = {2018} } @article{faucris.109991024, abstract = {The redox reaction of superoxide (KO2) with highly charged iron porphyrins (Fe(P4+), Fe(P8+), and Fe(P8-)) has been investigated in the ionic liquids (IL) [EMIM] [Tf2N] (1-ethyl-3-methylimidazolium bis (trifluoromethylsulfonyl)imide) and [EMIM] [B(CN)(4)] (1-ethyl-3-methylimidazolium tetracyanoborate) by using time-resolved UV/vis stopped-flow, electrochemistry, cryospray mass spectrometry, EPR, and XPS measurements. Stable KO2 solutions in [EMIM] [Tf2N] can be prepared up to a IS mM concentration and are characterized by a signal in EPR spectrum at g = 2.0039 and by the 1215 cm(-1) stretching vibration in the resonance Raman spectrum While the negatively charged iron porphyrin Fe(P8-) does not react with superoxide in IL, Fe(P4+) and Fe(P8+) do react in a two-step process (first a reduction of the Fe(III) to the Fe(II) form, followed by the binding of superoxide to Fe(II)). In the reaction with KO2, Fe(P4+) and Fe(P8+) show similar rate constants (e.g., in the case of Fe(P4+): k(1) = 18.6 +/- 0.5 M-1 s(-1) for the first reaction step, and k(2) = 2.8 +/- 0.1 M-1 s(-1) for the second reaction step). Notably, these rate constants are four to five orders of magnitude lower in [EMIM] [Tf2N] than in conventional solvents such as DMSO. The influence of the ionic liquid is also apparent during electrochemical experiments, where the redox potentials for the corresponding Fe(III)/Fe(II) couples are much more negative in [EMIM] [Tf2N] than in DMSO. This modified redox and kinetic behavior of the positively charged iron porphyrins results from their interactions with the anions of the ionic liquid, while the nucleophilicity of the superoxide is reduced by its interactions with the cations of the ionic liquid. A negligible vapor pressure of [EMIM][B(CN)(4)] and a sufficient enrichment of Fe(P8+) in a close proximity to the surface enabled XPS measurements as a case study for monitoring direct changes in the electronic structure of the metal centers during redox processes in solution and at liquid/solid interfaces.}, author = {Dees, Anne and Jux, Norbert and Tröppner, Oliver and Dürr, Katharina L. and Lippert, Rainer and Schmid, Martin and Kuestner, Bernd and Schluecker, Sebastian and Steinrück, Hans-Peter and Gottfried, J. Michael and Ivanovic-Burmazovic, Ivana}, doi = {10.1021/acs.inorgchem.5b00770}, faupublication = {yes}, journal = {Inorganic Chemistry}, pages = {6862-6872}, peerreviewed = {Yes}, title = {{Reactions} of {Superoxide} with {Iron} {Porphyrins} in the {Bulk} and the {Near}-{Surface} {Region} of {Ionic} {Liquids}}, volume = {54}, year = {2015} } @article{faucris.202402938, abstract = {We have investigated the adsorption and thermal reactivity of CO and C2H4 on well-defined bimetallic PtxAg1-x/Pt(111) surface alloys (with x=0.67, 0.50, 0.38 and 0.32) using insitu synchrotron-based high-resolution X-ray photoelectron spectroscopy. During low-temperature (140K) adsorption of CO, we find population of the energetically more stable Pt on-top site followed by the Pt bridge site, as known from clean Pt(111); CO does not adsorb on Ag facets under the applied conditions. The total CO coverage linearly decreases with Ag surface content. Upon heating, COon-top and CObridge desorb at higher temperatures than on bare Pt(111), for example, by approximate to 65K for COon-top for an Ag content of 33%. This shift is due to the well-known electronic ligand-effect of Ag atoms surrounding Pt atoms/clusters. For C2H4 adsorption on the AgPt alloys at low temperature (120K), we find two species in the C1s XP spectrum, each displaying a vibrational fine structure; this contrasts the situation on clean Pt(111), where only one species is found. Upon heating, ethylene reacts with ethylidyne being the dominant intermediate; in contrast to clean Pt(111), on the alloy surfaces the reaction to CCH3 occurs at much lower temperatures, e.g. by approximate to 60K for the alloy with 68% Ag, and no ethylene desorption is found.}, author = {Bauer, Udo and Späth, Florian and Düll, Fabian and Bachmann, Phillip and Steinhauer, Johann and Steinrück, Hans-Peter and Papp, Christian}, doi = {10.1002/cphc.201800044}, faupublication = {yes}, journal = {ChemPhysChem}, keywords = {carbon monoxide;ethylene;platinum;silver;X-ray photoelectron spectroscopy}, pages = {1432-1440}, peerreviewed = {Yes}, title = {{Reactivity} of {CO} and {C2H4} on {Bimetallic} {PtxAg1}-x/{Pt}(111) {Surface} {Alloys} {Investigated} by {High}-{Resolution} {X}-ray {Photoelectron} {Spectroscopy}}, volume = {19}, year = {2018} } @article{faucris.108616464, abstract = {Nanocluster arrays on graphene are suitable model systems for catalysis. We use this model system to study sulfur poisoning, which is a major deactivation process of heterogeneous catalysts. Using high-resolution X-ray photoelectron spectroscopy, we investigated the adsorption and desorption of CO on sulfur-poisoned graphene-supported palladium nanoparticles. We find that sulfur blocks CO adsorption sites, with hollow sites being most affected. From the unchanged desorption temperatures, we conclude that the Pd-CO bond strength is not altered by co-adsorbed sulfur. The degree of site blocking compared to the amount of sulfur indicates that the palladium nanoparticle surface is dominated by (111) and (100) facets.}, author = {Düll, Fabian and Späth, Florian and Bachmann, Philipp and Bauer, Udo and Steinrück, Hans-Peter and Papp, Christian}, doi = {10.1021/acs.jpcc.6b11480}, faupublication = {yes}, journal = {Journal of Physical Chemistry C}, month = {Jan}, pages = {1734-1741}, peerreviewed = {Yes}, title = {{Reactivity} of {CO} on {Sulfur}-{Passivated} {Graphene}-{Supported} {Palladium} {Nanocluster} {Arrays}}, volume = {121}, year = {2017} } @article{faucris.202404838, author = {Düll, Fabian and Späth, Florian and Bauer, Udo and Bachmann, Philipp and Steinhauer, Johann and Steinrück, Hans-Peter and Papp, Christian}, doi = {10.1021/acs.jpcc.8b01589}, faupublication = {yes}, journal = {Journal of Physical Chemistry C}, pages = {16008-16015}, peerreviewed = {unknown}, title = {{Reactivity} of {CO} on {Sulfur}-{Passivated} {Graphene}-{Supported} {Platinum} {Nanocluster} {Arrays}}, volume = {122}, year = {2018} } @article{faucris.107302184, abstract = {Nanocluster arrays on graphene (Gr) are intriguing model systems for catalysis. We studied the adsorption and oxidation of CO on Pt/Gr/Rh(111) with synchrotron-based high-resolution X-ray photoelectron spectroscopy. On the nanoclusters, CO is found to adsorb at three different sites: namely, on-top, bridge, and step. The C 1s spectra exhibit remarkable similarities to those on the stepped Pt(355) surface. Similar to the case for stepped Pt surfaces, a clear preference for the adsorption on the step sites is found, while the preference for the adsorption on the on-top site over the bridge site on the terraces is much less pronounced in comparison to that on Pt single crystals. Temperature-programmed X-ray photoelectron spectroscopy revealed an enhanced binding energy for the cluster step sites, similar to the situation on stepped Pt surfaces. The oxidation of CO on graphene-supported Pt nanoclusters follows a pseudo-first-order rate law. Applying an Arrhenius analysis, we found an activation energy of 13 &plusmn; 4 kJ/mol, which is much smaller than that on Pt(111), due to the more reactive step and kink sites on the nanoclusters.}, author = {Gotterbarm, Karin and Späth, Florian and Bauer, Udo and Bronnbauer, Carina and Steinrück, Hans-Peter and Papp, Christian}, doi = {10.1021/acscatal.5b00245}, faupublication = {yes}, journal = {ACS Catalysis}, pages = {2397--2403}, peerreviewed = {unknown}, title = {{Reactivity} of {Graphene}-{Supported} {Pt} {Nanocluster} {Arrays}}, volume = {5}, year = {2015} } @article{faucris.123939464, abstract = {The CO oxidation on different platinum model catalysts, in particular differently sized Pt particles on vertically aligned TiO nanotubes (d=80, l=200nm) was investigated by near-ambient-pressure X-ray photoelectron spectroscopy and simultaneous online gas analysis. The results are compared to the behavior on a TiO(110) rutile crystal with a similar Pt coverage and a Pt(111) single crystal. Temperature-programmed reaction experiments at total pressures of 10 to 1.0mbar, and a CO/O ratio of 1:4 were performed to evaluate the reactivity of the samples. The onset temperature of the reaction on the Pt/TiO nanotube samples was found to be lower than on Pt(111) and Pt/TiO(110) and to decrease with decreasing particle size. For all particle samples, a steep increase in reaction rate at a defined temperature was observed, and at high temperatures the reaction became mass transfer-limited in all cases. Isothermal measurements showed that no CO is adsorbed on the particles when CO oxidation has a high activity and metallic platinum is the active catalyst. Ageing of the TiO-supported samples is observed resulting in changes of the reaction onset and CO conversion.}, author = {Krick Calderon, Sandra and Grabau, Mathias and Yoo, Jeong Eun and Killian, Manuela and Schmuki, Patrik and Steinrück, Hans-Peter and Papp, Christian}, doi = {10.1002/cctc.201600913}, faupublication = {yes}, journal = {ChemCatChem}, keywords = {Nanotubes; Oxidation; Platinum; Supported catalysts; X-ray absorption spectroscopy}, pages = {564-572}, peerreviewed = {unknown}, title = {{Reactivity} of {TiO2} {Nanotube}-{Supported} {Platinum} {Particles} in the {CO} {Oxidation} {Reaction}}, volume = {9}, year = {2017} } @article{faucris.202405177, author = {Bauer, Udo and Gleichweit, Christoph and Höfert, Oliver and Späth, Florian and Gotterbarm, Karin and Steinrück, Hans-Peter and Papp, Christian}, doi = {10.1016/j.susc.2018.01.001}, faupublication = {yes}, journal = {Surface Science}, keywords = {Benzene; High-resolution X-ray photoelectron spectroscopy; Molybdenum; Ethylene; Heterogeneous catalysis; Transition metal carbides; Near edge X-ray absorption fine structure; Temperature programmed desorption}, peerreviewed = {Yes}, title = {{Reactivity} studies of ethylene, benzene and cyclohexane on carbide-modified {Mo}(110) using high resolution {X}-ray photoelectron spectroscopy}, year = {2018} } @article{faucris.107835464, abstract = {A perspective is given on the potential of X-ray photoelectron spectroscopy to investigate ionic liquid (IL) interfaces and related bulk properties. To allow for cross-correlation of different IL properties, the study is restricted to imidazolium-based systems. By systematic variation of alkyl chain lengths, by investigation of different anions, and by introduction of functional groups detailed information on surface orientation, enrichment effects, cation-anion interactions, and the correlation to macroscopic properties such as density and surface tension of ILs are derived. Furthermore, the molecular arrangement and growth behaviour of ultrathin ionic liquid layers on various substrates, in situ monitoring of chemical reactions, and the dissolution of transition metal complexes are addressed. &copy; 2012 the Owner Societies.}, author = {Steinrück, Hans-Peter}, doi = {10.1039/c2cp24087d}, faupublication = {yes}, journal = {Physical Chemistry Chemical Physics}, pages = {5010-5029}, peerreviewed = {Yes}, title = {{Recent} developments in the study of ionic liquid interfaces using {X}-ray photoelectron spectroscopy and potential future directions}, volume = {14}, year = {2012} } @article{faucris.121283184, abstract = {An X-ray photoelectron spectroscopy (XPS) study of Pt(II) and Pt(IV) complexes dissolved in ionic liquids (ILs) revealed the occurrence of a rich redox chemistry, which is partly induced by X-ray radiation. Depending on the IL anion either a reduction of Pt(IV) to Pt(II) in the case of ethylsulfate ([EtOSO])-based ILs, or an oxidation of Pt(II) to Pt(IV) in the case of bis[(trifluoromethyl)sulfonyl]imide ([TfN] )-based ILs was observed upon X-ray irradiation. Moreover, surface enrichment or depletion effects of the Pt complexes were deduced from angle-resolved XPS (ARXPS) data; while the Pt complexes dissolved in imidazolium-based ILs tended to deplete from the surface, in pyrrolidinium-based solutions a surface enrichment of the Pt complexes was observed. &copy; 2013 Elsevier B.V. All rights reserved.}, author = {Kolbeck, Claudia and Taccardi, Nicola and Paape, Natalia and Schulz, Peter and Wasserscheid, Peter and Steinrück, Hans-Peter and Maier, Florian}, doi = {10.1016/j.molliq.2013.07.007}, faupublication = {yes}, journal = {Journal of Molecular Liquids}, pages = {103-113}, peerreviewed = {Yes}, title = {{Redox} chemistry, solubility, and surface distribution of {Pt}({II}) and {Pt}({IV}) complexes dissolved in ionic liquids}, volume = {192}, year = {2014} } @article{faucris.121186164, abstract = {For the heterovalent system ZnSe/GaAs(100), we have investigated the influence of a Te pretreatment of the substrate on the electronic structure of the interface by photoelectron spectroscopy. We have paid special attention to correctly determine the valence band maximum in a k-resolved fashion, including the use of photon energies which enable excitation at the &Gamma; point. We find that the Te pretreatment leads to a decrease of the valence band discontinuity as large as 0.3 eV. From photoemission depth profiling we conclude that some Te atoms remain localized at the interface, thus causing the change of the valence band offset while others float on the ZnSe surface, probably acting as surfactants. &copy; 2001 American Institute of Physics.}, author = {Gleim, Thomas and Heske, C. and Umbach, E. and Schumacher, C. and Faschinger, W. and Ammon, Christian and Probst, Marc and Steinrück, Hans-Peter}, doi = {10.1063/1.1358366}, faupublication = {yes}, journal = {Applied Physics Letters}, pages = {1867-1869}, peerreviewed = {Yes}, title = {{Reduction} of the {ZnSe}/{GaAs}(100) valence band offset by a {Te} interlayer}, volume = {78}, year = {2001} } @article{faucris.110033924, abstract = {The (1 0 0) surface of CdTe has been studied by reflection electron energy loss spectroscopy (REELS). The sample was prepared in situ in our UHV system and shows a c (2&times;2) reconstruction. The angle resolved REELS measurements for primary energies between 30 and 100 eV show distinct losses between 2 and 15eV that are attributed to interband transitions, d-band transitions as well as surface and bulk plasmons. The experimental investigations are accompanied by ab initio calculations (LDA/RPA) for the bulk loss function -Im(1/&epsilon;) of CdTe. From these calculations the surface loss function -Im(1/(&epsilon; + 1)) is determined. The dominant loss feature at 8.7 eV in the experimental spectra is assigned to a surface plasmon. Its energetic position is &sim; 1 eV below the maximum of the calculated surface loss function and earlier measurements for the nonpolar CdTe(1 1 0) surface. This shift is attributed to the reconstruction of the CdTe(1 0 0) surface that leads to a reduced surface charge density. &copy; 1998 Elsevier Science B.V. All rights reserved.}, author = {Dröge, H. and Fleszar, A. and Steinrück, Hans-Peter}, faupublication = {no}, journal = {Journal of Crystal Growth}, pages = {208-212}, peerreviewed = {Yes}, title = {{REELS} measurements on a {CdTe}(1 0 0) surface}, url = {https://www.scopus.com/record/display.uri?eid=2-s2.0-11544358920&origin=inward}, year = {1998} } @article{faucris.120311884, abstract = {Approaches for the selective self-assembly of functionalized carbon allotropes from solution are developed and validated for 0D-fullerenes, 1D-carbon nanotubes and 2D-graphene. By choosing the right molecular interaction of self-assembled monolayers (serving the surface) with the functionalization features of carbon materials, which provide the solubility but also serve the driving force for assembly, we demonstrate a region-selective and self-terminating assembly of the materials. Active layers of the carbon allotropes can be selectively deposited in the channel region of thin-film transistor (TFT) devices by this approach. As an example for a 0D system, molecules of C functionalized octadecylphosphonic acids are used to realize self-assembled monolayer field-effect transistors (SAMFETs) based on a selective molecular exchange reaction of stearic acid in the channel region. For noncovalently functionalized single-walled carbon nanotubes (SWCNTs) and graphene oxide (GO) flakes, the electrostatic Coulomb interactions between the functional groups of the carbon allotropes and the charged head groups of a SAM dielectric layer are utilized to implement the selective deposition. © 2013 American Chemical Societ}, author = {Wang, Zhenxing and Mohammadzadeh, Saeideh and Schmaltz, Thomas and Kirschner, Johannes and Khassanov, Artöm and Eigler, Siegfried and Mundloch, Udo and Backes, Claudia and Steinrück, Hans-Peter and Magerl, Andreas and Hauke, Frank and Hirsch, Andreas and Halik, Marcus and Hauke, Frank}, doi = {10.1021/nn405488n}, faupublication = {yes}, journal = {Acs Nano}, pages = {11427-11434}, peerreviewed = {Yes}, title = {{Region}-{Selective} {Self}-{Assembly} of {Functionalized} {Carbon} {Allotropes} from {Solution}}, url = {http://pubs.acs.org/doi/abs/10.1021/nn405488n}, volume = {7}, year = {2013} } @article{faucris.119847684, abstract = {Two-dimensional spectral images, as opposed to one-dimensional spectra, are crucial for both recognizing the presence and verifying the removal of photoemission features in Auger-yield NEXAFS. We present a procedure for removing such photoemission features, which relies on describing the measured Auger yield NEXAFS image as three simple, one-dimensional spectra: NEXAFS, Auger, and XPS. This allows for a very successful and fast removal of even extreme photoemission features, as illustrated by four examples. The procedure requires no additional reference measurements other than photon flux, and provides a significant amount of additional information, such as NEXAFS, Auger and XPS spectra and images, which can be used to verify the validity of the underlying assumptions and success of the cleanup process. (C) 2017 Elsevier B.V. All rights reserved.}, author = {Lytken, Ole and Wechsler, Daniel and Steinrück, Hans-Peter}, doi = {10.1016/j.elspec.2017.05.012}, faupublication = {yes}, journal = {Journal of Electron Spectroscopy and Related Phenomena}, keywords = {X-ray absorption fine structure (XAFS);X-ray absorption near edge structure (XANES);Near edge X-ray absorption fine structure (NEXAFS);Photoemission removal;Photoemission correction;Image analysis}, pages = {35-39}, peerreviewed = {Yes}, title = {{Removing} photoemission features from {Auger}-yield {NEXAFS} spectra}, volume = {218}, year = {2017} } @article{faucris.108484024, abstract = {Near edge x-ray absorption spectra and decay electron spectra for resonant and nonresortant excitations in the C 1s and N 1s regions have been measured for condensed furan (CHO) and pyrrole (CH NH) layers. The decay spectra after resonant excitation into the lowest unoccupied orbital (&pi;*) are pure autoionization spectra. The participant channels show strong resonant enhancements of the photoelectron peaks, in particular after excitation of the C 1s core electrons. Overall however, the spectra are dominated by the spectator channels. The spectator spectra resemble the normal Auger spectra shifted by spectator shifts of &asymp;4 eV for furan and &asymp;2.5 eV for pyrrole. For furan the participant spectra for excitation at the two different carbon atoms show significant differences that can be qualitatively understood in terms of a simple one-electron picture by considering the localization of the corresponding orbitals on the core hole. The decay spectra after excitation into the &pi;* orbital show negligible enhancement of the participant channel, a strongly reduced spectator shift, and less-pronounced structures than at higher photon energies. The latter is attributed to a competition of spectator decay and normal Auger decay after internal photoionization into Rydberg derived bands in the condensate. For excitations into the &sigma;*-resonances pure Auger spectra are observed, indicating that these resonances fully ionize before core decay takes place. &copy; 1993 American Institute of Physics.}, author = {Mauerer, M. and Zebisch, P. and Weinelt, Martin and Steinrück, Hans-Peter}, doi = {10.1063/1.465144}, faupublication = {no}, journal = {Journal of Chemical Physics}, pages = {3343-3352}, peerreviewed = {Yes}, title = {{Resonant} excitation and decay of core holes in condensed layers of furan and pyrrole}, volume = {99}, year = {1993} } @article{faucris.107301964, abstract = {Understanding the adsorption and reaction between hydrogen and graphene is of fundamental importance for developing graphene-based concepts for hydrogen storage and for the chemical functionalization of graphene by hydrogenation. Recently, theoretical studies of single-sided hydrogenated graphene, so called graphone, predicted it to be a promising semiconductor for applications in graphene-based electronics. Here, we report on the synthesis of graphone bound to a Ni(111) surface. We investigate the formation process by X-ray photoelectron spectroscopy (XPS), temperature-programmed desorption (TPD), and density-functional theory calculations, showing that the hydrogenation of graphene with atomic hydrogen indeed leads to graphone, that is, a hydrogen coverage of 1ML (4.2 wt&thinsp;\%). The dehydrogenation of graphone reveals complex desorption processes that are attributed to coverage-dependent changes in the activation energies for the associative desorption of hydrogen as molecular H2 .}, author = {Zhao, Wei and Gebhardt, Julian and Späth, Florian and Gotterbarm, Karin and Gleichweit, Christoph and Steinrück, Hans-Peter and Görling, Andreas and Papp, Christian}, doi = {10.1002/chem.201404938}, faupublication = {yes}, journal = {Chemistry - A European Journal}, keywords = {dehydrogenation;density functional calculations;graphene;graphone;hydrogenation;X-ray photoelectron spectroscopy}, pages = {3347--3358}, peerreviewed = {Yes}, title = {{Reversible} {Hydrogenation} of {Graphene} on {Ni}(111)-{Synthesis} of ’{Graphone}’}, volume = {21}, year = {2015} } @article{faucris.117546264, abstract = {We investigated the adsorption behavior of Co(II)-5,10,15,20-tetrakis-(3,5-di-tert-butylphenyl)-porphyrin (CoTTBPP) on Cu(111) by scanning tunneling microscopy (STM). At room temperature (RT), the coverage dependent adsorption behavior follows an expected scheme: at low coverage step decoration is found, which evolves into supramolecular domains with a hexagonal order at higher coverage. Interestingly, upon cooling the sample to 180 K the occurrence of a clearly distinguishable coexisting herringbone phase is observed. Upon heating to RT again, the herringbone phase vanishes. Thus a temperature dependent, fully reversible phase transition was observed. High resolution STM micrographs allow for the determination of the intramolecular conformations which are different for the two supramolecular arrangements. In addition, we studied the bias voltage dependent appearance of the molecule in STM and assigned a dominant contribution of the central Co at negative bias voltages close to the Fermi edge to the occupied d orbital. Interestingly, the herringbone phase, which dominates at 180 K, exhibits a significantly higher molecular density than the monomodal hexagonal arrangement at RT, which is in line with the &quot;normal&quot; behavior of freezing substances.}, author = {Steinrück, Hans-Peter and Stark, Michael Werner and Ditze, Stefanie and Thomann, Michael and Lungerich, Dominik and Jux, Norbert and Marbach, Hubertus}, doi = {10.1016/j.susc.2015.11.024}, faupublication = {yes}, journal = {Surface Science}, keywords = {Bias voltage dependence; Intramolecular conformation; Porphyrin; Reversible phase transition; Scanning tunneling microscopy; Self-assembly}, pages = {255-262}, peerreviewed = {Yes}, title = {{Reversible} thermally induced phase transition in ordered domains of {Co}({II})-5,10,15,20-tetrakis-(3,5-di-tert-butylphenyl)-porphyrin on {Cu}(111)}, volume = {650}, year = {2016} } @article{faucris.123155604, abstract = {We have studied the coverage-dependent adsorption behavior of Ni(II)-5,10,15,20-tetraphenyltetra-benzoporphyrin on Cu(111) by scanning tunneling microscopy (STM) at room temperature. At medium coverages, the molecules self-assemble into two-dimensional islands, due to mutual stabilization through intermolecular interactions. Altogether, three different supramolecular arrangements coexist at low-to-medium coverages. On the basis of high-resolution STM images and density functional theory calculations, models for the three arrangements and the corresponding intramolecular conformations of the individual molecules are proposed. The observed polymorphism is attributed to a complex interplay of specific T-type and pi-pi stacking interactions between the phenyl groups. For Ni(II)-meso-tetrakis (4-tert-butylphenyl) benzoporphyrin, in which the aromatic periphery is modified by the attachment of tert-butyl groups, only one supramolecular arrangement on Cu(111) is found. This difference highlights the fact that the choice of peripheral ligands of the porphyrin derivatives plays an important role in the fabrication and tailoring of functional molecular architectures.}, author = {Lepper, Michael and Zhang, Liang and Stark, Michael Werner and Ditze, Stefanie and Lungerich, Dominik and Jux, Norbert and Hieringer, Wolfgang and Steinrück, Hans-Peter and Marbach, Hubertus}, doi = {10.1021/acs.jpcc.5b05451}, faupublication = {yes}, journal = {Journal of Physical Chemistry C}, pages = {19897-19905}, peerreviewed = {Yes}, title = {{Role} of {Specific} {Intermolecular} {Interactions} for the {Arrangement} of {Ni}({II})-5, 10, 15, 20-{Tetraphenyltetrabenzoporphyrin} on {Cu}(111)}, volume = {119}, year = {2015} } @article{faucris.121242924, abstract = {Temperature-dependent structural changes of Ni monolayers on Cu(111) and the adsorption of benzene on these layers were investigated using photoelectron spectroscopy (XPS) and low energy electron diffraction (LEED). Ni films evaporated at 120 K show a sharp (1 x 1) LEED pattern after annealing to 300 K. Further annealing to 600 K leads to the segregation of Cu atoms on top of the Ni film. This is seen from the appearance of a surface core level shift in the Cu 2p XPS signal. The Ni2p signal does not show any shifts in this temperature range; only annealing to 800 K leads to a change in the Ni 2p peak energy which indicates the formation of a Cu-Ni bulk alloy. Adsorption of benzene on the Ni-adlayer (annealed to 300 K) causes a small peak shift in the Ni 2p signal. The C 1s signal indicates molecularly chemisorbed benzene up to 300 K. Further annealing to 500 K leads to the decomposition of benzene into hydrogen and carbon which remains on the surface and forms a stable bond with the Ni-adlayer, preventing Cu segregation up to 500 K. &copy; 2001 Elsevier Science B.V. All rights reserved.}, author = {Domnick, Ralph and Held, Georg and Koschel, Herbert and Ammon, Christian and Steinrück, Hans-Peter}, doi = {10.1016/S0039-6028(01)00717-8}, faupublication = {yes}, journal = {Surface Science}, pages = {1292-1297}, peerreviewed = {Yes}, title = {{Segregation} effects and chemical properties of nickel monolayers on {Cu}(1 1 1)}, year = {2001} } @article{faucris.262982956, abstract = {We present detailed studies on the covalent adsorption of molecular oxygen and atomic hydrogen on the hexagonal boron nitride (h-BN) nanomesh on Rh(111). The functionalization of this two-dimensional (2D) material was investigated under ultra-high vacuum conditions using synchrotron radiation-based in situ high-resolution X-ray photoelectron spectroscopy, temperature-programmed X-ray photoelectron spectroscopy and ultraviolet photoelectron spectroscopy. We are able to provide a deep insight into the adsorption behavior and thermal stability of oxygen and hydrogen on h-BN/Rh(111). Oxygen functionalization was achieved via a supersonic molecular beam while hydrogen functionalization was realized using an atomic hydrogen source. Adsorption of the respective species was observed to occur selectively in the pores of h-BN leading to spatially defined modification of the 2D layer. The adsorption of the observed molecular oxygen species was found to be an activated process that requires high-energy oxygen molecules. Upon heating to 700 K, oxygen functionalization was observed to be almost reversible except for small amounts of boron oxides evolving due to the reaction of oxygen with the 2D material. Hydrogen functionalization of h-BN/Rh(111) was fully reversed upon heating to about 640 K.}, author = {Freiberger, Eva Marie and Späth, Florian and Bauer, Udo and Düll, Fabian and Bachmann, Philipp and Steinhauer, Johann and Hemauer, Felix and Waleska, Natalie and Schwaab, Valentin and Steinrück, Hans-Peter and Papp, Christian}, doi = {10.1002/chem.202101946}, faupublication = {yes}, journal = {Chemistry - A European Journal}, note = {CRIS-Team WoS Importer:2021-08-20}, peerreviewed = {Yes}, title = {{Selective} {Oxygen} and {Hydrogen} {Functionalization} of the h-{BN}/{Rh}(111) {Nanomesh}}, year = {2021} } @article{faucris.258181718, abstract = {We investigated the adsorption of 2H-5,10,15,20-Tetracyanophenyl-Tetrabenzoporphyrin (2H-TCNPTBP) molecules on Cu(111) by scanning tunneling microscopy in ultrahigh vacuum at room temperature. Three types of network structures are observed to coexist on the surface. The first two, a porous Kagome lattice and a porous quadratic structure, are stabilized by cyano-Cu-cyano bonds with Cu adatoms; the third is a close-packed hexagonal network, with much weaker intermolecular H-bonds and dipole-dipole interactions of oppositely oriented cyano end groups. The coexistence of the three structures is attributed to very similar energetics. While the two metal-coordinated porous structures with identical molecular density are stabilized by the energy gain due to the network formation, the hexagonal network compensates the weaker intermolecular interactions by a factor of 2.3 higher molecular density; furthermore, kinetic stabilization might play a role. Our results show that cyano functionalization of benzoporphyrins gives rise to unusual two-dimensional self-Assembled lattice structures. }, author = {Adhikari, Rajan and Kuliga, Jan and Ruppel, Michael and Jux, Norbert and Marbach, Hubertus and Steinrück, Hans-Peter}, doi = {10.1021/acs.jpcc.1c00746}, faupublication = {yes}, journal = {Journal of Physical Chemistry C}, note = {CRIS-Team Scopus Importer:2021-05-14}, peerreviewed = {Yes}, title = {{Self}-{Assembled} {2D}-{Coordination} {Kagome}, {Quadratic}, and {Close}-{Packed} {Hexagonal} {Lattices} {Formed} from a {Cyano}-{Functionalized} {Benzoporphyrin} on {Cu}(111)}, year = {2021} } @article{faucris.123155824, abstract = {A systematic scanning tunnelling microscopy investigation of the self-assembly and of thermally induced conformational changes of Ni(II)-meso-tetrakis (4-tert-butylphenyl) benzoporphyrin (Ni-TTBPBP) on Cu(111) is presented. At room temperature, Ni-TTBPBPs diffuse on the surface and self-assemble into ordered islands with well-defined registry to the substrate, with two different azimuthal orientations. The formation of the characteristic supramolecular structure is attributed to van der Waals interactions between the tert-butyl groups. Upon moderate heating, the intramolecular conformation changes irreversibly due to a dehydrogenative intramolecular aryl-aryl coupling reaction. This reaction is coverage dependent, with a lower rate at higher initial coverage; this behaviour is attributed to a stabilization of Ni-TTBPBP in the ordered islands at higher coverage.}, author = {Zhang, Liang and Lepper, Michael and Stark, Michael Werner and Lungerich, Dominik and Jux, Norbert and Hieringer, Wolfgang and Steinrück, Hans-Peter and Marbach, Hubertus}, doi = {10.1039/c5cp01490e}, faupublication = {yes}, journal = {Physical Chemistry Chemical Physics}, month = {Jan}, pages = {13066-13073}, peerreviewed = {Yes}, title = {{Self}-assembly and coverage dependent thermally induced conformational changes of {Ni}({II})-meso-tetrakis (4-tert-butylphenyl) benzoporphyrin on {Cu}(111)}, volume = {17}, year = {2015} } @article{faucris.267475145, abstract = {Fundamental studies on the interaction of porphyrin molecules with oxide surfaces are important due to the relevance of these systems in emerging technologies. In this work, we used X-ray photoelectron spectroscopy (XPS) to study the interaction of solution-deposited monophosphonic acid tetraphenylporphyrin (MPTPP) molecules with well-defined rutile TiO<inf>2</inf>(110)-(1×1) surfaces as a function of coverage and temperature. We found that molecules adsorb mainly in their free-base form with some molecules protonating on the surface at room temperature. In agreement with the behavior of carboxylic acid functionalized porphyrin molecules, raising the temperature results in porphyrin self-metalation and the temperature onset for self-metalation shifts to higher values as the coverage is increased. Furthermore, we found that self-metalation is accompanied by surface reduction, and we propose a mechanism based on the formation of oxygen vacancies driven by water desorption. Our findings contribute towards the understanding of the rich surface chemistry that porphyrin molecules have on oxide surfaces.}, author = {Fernández, Cynthia C. and Wechsler, Daniel and Lytken, Ole and Steinrück, Hans-Peter and Williams, Federico J.}, doi = {10.1016/j.susc.2021.122005}, faupublication = {yes}, journal = {Surface Science}, keywords = {Porphyrin molecules; Self-metalation; TiO}, note = {CRIS-Team Scopus Importer:2021-12-24}, peerreviewed = {Yes}, title = {{Self}-metalation of monophosphonic acid tetraphenylporphyrin on {TiO2}(110)-(1×1)}, volume = {717}, year = {2022} } @article{faucris.108287124, abstract = {The influence of preadsorbed sulfur on the adsorption of CO on Pt(355) and Pt(322) is investigated systematically for sulfur precoverages between 0.02 and 0.30ML by insitu x-ray photoelectron spectroscopy of the C 1s and S 2p core levels. The two surfaces have the same nominal terrace width of 5 atomic rows, but different step orientation. For both, at low temperatures (130 and 150K), S preferentially adsorbs at the steps and passivates them for COadsorption. The required S precoverage is significantly smaller for Pt(322), because of the lower number of steps as a result of the S-induced double-step formation. Upon heating, population of step sites with CO occurs due to irreversible CO/S site exchange. At low S precoverages, the characteristic transition temperatures of 165K for Pt(355) and 245K for Pt(322) are significantly different, indicating a higher activation barrier for the CO/S site exchange process for Pt(322). For medium to high S precoverages the transition temperature stays unchanged for Pt(322) but increases for Pt(355). The observed behavior is attributed to a kinetic passivation of the steps by sulfur at low temperatures, which is lifted upon heating. © 2009 IOP Publishing Lt}, author = {Streber, Regine and Papp, Christian and Lorenz, Michael Peter Andreas and Bayer, Andreas and Wickert, Sandra and Schöppke, Matthias and Denecke, Reinhard and Steinrück, Hans-Peter}, doi = {10.1088/0953-8984/21/13/134018}, faupublication = {yes}, journal = {Journal of Physics: Condensed Matter}, pages = {134018 1-13}, peerreviewed = {Yes}, title = {{Site} blocking and {CO}/sulfur site exchange processes on stepped {Pt} surfaces}, volume = {21}, year = {2009} } @article{faucris.121503624, abstract = {The adsorption and thermal evolution of deuterated and nondeuterated benzene on Ni(111) has been studied by in situ high-resolution x-ray photoelectron spectroscopy. The recorded C 1s spectra show vibrational fine structure due to vibrational excitations of the C-H bonds in the ionic final state. Furthermore, different adsorption sites can be identified, since carbon atoms within the same molecule, but with different positions relative to the substrate have different C 1s binding energies. At 200 K for both C6 H6 and C6 D6 a well ordered (7&times;7) R19.1&deg;superstructure is observed at saturation of the chemisorbed layer, with a nominal coverage of 0.143 ML. From a quantitative analysis of the XP spectra collected during adsorption one finds that up to a coverage of 0.10 ML benzene occupies only bridge adsorption sites. At higher coverage, a change to hcp hollow sites, accompanied by a rotation of the molecules by 30&deg;, occurs for C6 H6 and C6 D6. In contrast to these results, an isotopic effect is found for adsorption at 125 K. While the adsorption behavior for C6 D6 is similar as at 200 K, for C6 H6 no change in adsorption site is observed, i.e., up to saturation of the chemisorbed layer bridge sites are occupied. Only upon heating, a site change from bridge to hcp hollow of the adsorbed C6 H6 is induced, starting around 180 K. A simple explanation for the observed behavior is proposed. &copy; 2006 The American Physical Society.}, author = {Papp, Christian and Fuhrmann, Thomas and Tränkenschuh, Barbara and Denecke, Reinhard and Steinrück, Hans-Peter}, doi = {10.1103/PhysRevB.73.235426}, faupublication = {yes}, journal = {Physical Review B}, peerreviewed = {Yes}, title = {{Site} selectivity of benzene adsorption on {Ni}(111) studied by high-resolution x-ray photoelectron spectroscopy}, volume = {73}, year = {2006} } @article{faucris.109608004, abstract = {Hydrogen can be stored conveniently using so-called liquid organic hydrogen carriers (LOHCs), for example, N-ethylcarbazole (NEC), which can be reversibly hydrogenated to dodecahydro-N-ethylcarbazole (H-NEC). In this study, we focus on the dealkylation of H-NEC, an undesired side reaction, which competes with dehydrogenation. The structural sensivity of dealkylation was studied by high-resolution X-ray photoelectron spectroscopy (HR-XPS) on AlO-supported Pt model catalysts and Pt(111) single crystals. We show that the morphology of the Pt deposit strongly influences LOHC degradation via C-N bond breakage. On smaller, defect-rich Pt particles, the onset of dealkylation is shifted by 90 K to lower temperatures as compared to large, well-shaped particles and well-ordered Pt(111). We attribute these effects to a reduced activation barrier for C-N bond breakage at low-coordinated Pt sites, which are abundant on small Pt aggregates but are rare on large particles and single crystal surfaces. &copy; 2014 American Chemical Society.}, author = {Amende, Maximilian and Gleichweit, Christoph and Schernich, Stefan and Höfert, Oliver and Lorenz, Michael Peter Andreas and Zhao, Wei and Koch, Marcus and Obesser, Katharina and Papp, Christian and Wasserscheid, Peter and Steinrück, Hans-Peter and Libuda, Jörg}, doi = {10.1021/jz500157r}, faupublication = {yes}, journal = {Journal of Physical Chemistry Letters}, pages = {1498-1504}, peerreviewed = {Yes}, title = {{Size} and structure effects controlling the stability of the liquid organic hydrogen carrier dodecahydro- {N} -ethylcarbazole during dehydrogenation over pt model catalysts}, volume = {5}, year = {2014} } @article{faucris.120177024, abstract = {We studied the adsorption and reaction of sulfur dioxide on clean and oxygen precovered platinum surfaces by in situ high resolution X-ray photoelectron spectroscopy and discuss earlier, contradicting results. On the clean surface we find flat lying and upright standing SO, adsorbing in similar amounts at low temperature. Upon heating, the ratio changes strongly favoring the standing SO; subsequently almost all SO desorbs. On the oxygen precovered surface the standing SO is preferably populated and even at low temperatures a direct reaction of SO to SO occurs. Upon heating, SO oxidation to SO and subsequently to SO is found. © 2010 Elsevier B.V. All rights reserve}, author = {Streber, Regine and Papp, Christian and Lorenz, Michael Peter Andreas and Höfert, Oliver and Darlatt, Erik and Bayer, Andreas and Denecke, Reinhard and Steinrück, Hans-Peter}, doi = {10.1016/j.cplett.2010.06.007}, faupublication = {yes}, journal = {Chemical Physics Letters}, pages = {188-192}, peerreviewed = {Yes}, title = {{SO2} adsorption and thermal evolution on clean and oxygen precovered {Pt}(111)}, volume = {494}, year = {2010} } @article{faucris.119848344, abstract = {Liquid binary Pd-Ga alloys with low Pd contents of 0.8, 1.8, and 4.7at% of Pd were examined as a function of sample temperature in ultra-high vacuum by using angle-resolved XPS. Upon cooling from 750 to 400K, a pronounced temperature-dependence of the Pd concentration in the liquid phase was observed, which was explained by the transition from the pure liquid phase to a two-phase system, consisting of a solid Ga5Pd phase and a Pd-depleted liquid Pd-Ga alloy. In the liquid Pd-Ga alloy, Pd is always depleted from the topmost interface layer, as deduced from angle-resolved XPS at 0 and 80 degrees emission, independent of temperature and Pd concentration. This observation is interpreted as an inhomogeneous depth distribution function of Pd, that is, the segregation of Ga to the surface of the liquid phase. The results of a DFT-based molecular dynamics simulation (MD) independently show interfacial stratification of Ga and an inhomogeneous Pd distribution along the surface normal. The evaluation of the experimental data with a rigid layer model based on the MD calculations leads to excellent agreement with the simulation.}, author = {Grabau, Mathias and Erhard, Jannis and Taccardi, Nicola and Krick Calderon, Sandra and Wasserscheid, Peter and Görling, Andreas and Steinrück, Hans-Peter and Papp, Christian}, doi = {10.1002/chem.201703627}, faupublication = {yes}, journal = {Chemistry - A European Journal}, keywords = {DFT MD;gallium;liquid-metal catalysis;palladium;XPS}, pages = {17701-17706}, peerreviewed = {Yes}, title = {{Spectroscopic} {Observation} and {Molecular} {Dynamics} {Simulation} of {Ga} {Surface} {Segregation} in {Liquid} {Pd}-{Ga} {Alloys}}, volume = {23}, year = {2017} } @article{faucris.230918407, abstract = {In light of increasing interest in the development of organic-organic multicomponent heterostructures on metals, this molecular-scale study investigates prototypical composite systems of ultrathin porphyrin and ionic liquid (IL) films on metallic supports under well-defined ultrahigh vacuum conditions. By means of angle-resolved X-ray photoelectron spectroscopy, we investigated the adsorption, stability, and thermal exchange of the resulting films after sequential physical vapor deposition of the free-base porphyrin 5,10,15,20-tetraphenylporphyrin, 2H-TPP, and the IL 1-methyl-3-octylimidazolium hexafluorophosphate, [C<inf>8</inf>C<inf>1</inf>Im][PF<inf>6</inf>], on Ag(111) and Au(111). 2H-TPP shows two-dimensional growth of up to two closed molecular layers on Ag(111) and Au(111) and three-dimensional island growth for thicker films. IL films on top of a monolayer of 2H-TPP exhibit Stranski-Krastanov-like growth and are stable up to 385 K. The 2H-TPP layer leads to destabilization of the IL films, compared to the IL in direct contact with the bare metals, by inhibiting the specific adsorption of the ions on the metal surfaces. When the porphyrin is deposited on top of [C<inf>8</inf>C<inf>1</inf>Im][PF<inf>6</inf>] at low temperature, the 2H-TPP molecules adsorb on top of the IL film at first but replace the IL at the IL/metal interfaces upon heating above 240 K. This exchange process is most likely driven by the higher adsorption energy of 2H-TPP on Ag(111) and Au(111) surfaces, as compared to the IL. The behavior observed on Ag(111) and Au(111) is identical. The results are highly relevant for the stability of porphyrin/IL-based thin film catalyst systems and molecular devices, and more generally, stacked organic multilayer architectures.}, author = {Lexow, Matthias and Massicot, Stephen and Maier, Florian and Steinrück, Hans-Peter}, doi = {10.1021/acs.jpcc.9b08531}, faupublication = {yes}, journal = {Journal of Physical Chemistry C}, note = {CRIS-Team Scopus Importer:2019-12-31}, peerreviewed = {Yes}, title = {{Stability} and {Exchange} {Processes} in {Ionic} {Liquid}/{Porphyrin} {Composite} {Films} on {Metal} {Surfaces}}, year = {2019} } @article{faucris.108387224, abstract = {We derive the kinetics for an adsorbate with strong nearest neighbor repulsion and additional second neighbor lateral interactions, starting from a kinetic lattice gas model. We then make the connection with site exclusion, first, as a demonstration, for an adsorbate with one adsorption site and next with both top and bridge adsorption, to elucidate the principal effects on sticking coefficients and desorption spectra. This paper is restricted to one-dimensional systems. &copy; 2002 Elsevier Science B.V. All rights reserved.}, author = {Payne, Stephen H. and Kreuzer, Hans Jürgen and Kinne, Martin and Denecke, Reinhard and Steinrück, Hans-Peter}, doi = {10.1016/S0039-6028(02)01731-4}, faupublication = {yes}, journal = {Surface Science}, keywords = {Equilibrium thermodynamics and statistical mechanics; Models of surface kinetics; Adsorption kinetics; Sticking; Thermal desorption; Single crystal surfaces}, pages = {174-202}, peerreviewed = {Yes}, title = {{Strong} repulsion and site exclusion in a system with ontop and bridge sites on a one-dimensional lattice: {Equilibrium} and kinetics}, url = {http://www.sciencedirect.com/science/article/pii/S0039602802017314}, volume = {513}, year = {2002} } @article{faucris.307869009, abstract = {We investigated the adsorption behavior of a mixture of six 2H-tetrakis-(3, 5-di-tert-butylphenyl)(x)benzoporphyrins (2H-diTTBP(x)BPs, x=0, 1, 2-cis, 2-trans, 3, and 4) on Ag(111), Cu(111) and Cu(110) at room temperature by scanning tunneling microscopy (STM) under ultra-high vacuum conditions. On Ag(111), we observe an ordered two-dimensional square phase, which is stable up to 400 K. On Cu(111), the same square phase coexists with a stripe phase, which disappears at 400 K. In contrast, on Cu(110), 2H-diTTBP(x)BPs adsorb as immobile isolated molecules or dispersed short chains along the [1 (Formula presented.) 0] substrate direction, which remain intact up to 450 K. The stabilization of the 2D supramolecular structures on Ag(111) and Cu(111), and of the 1D short chains on Cu(110) is attributed to van der Waals interactions between the tert-butyl and phenyl groups of neighboring molecules. From high-resolution STM, we can assign all six 2H-diTTBP(x)BPs within the ordered structures. Moreover, we deduce a crown shape quadratic conformation on Ag(111) and Cu(111), an additional saddle-shape on Cu(111), and an inverted structure and a quadratic appearance on Cu(110). The different conformations are attributed to the different degree of interaction of the iminic nitrogen atoms of the isoindole and pyrrole groups with the substrate atoms.}, author = {Adhikari, Rajan and Brox, Jan and Massicot, Stephen and Ruppel, Michael and Jux, Norbert and Marbach, Hubertus and Steinrück, Hans-Peter}, doi = {10.1002/cphc.202300355}, faupublication = {yes}, journal = {ChemPhysChem}, keywords = {2H-diTTBP(x)BPs; benzoporphyrin; isoindole groups; scanning tunneling microscopy; self-assembly}, note = {CRIS-Team Scopus Importer:2023-07-21}, peerreviewed = {Yes}, title = {{Structure} and {Conformation} of {Individual} {Molecules} upon {Adsorption} of a {Mixture} of {Benzoporphyrins} on {Ag}(111), {Cu}(111), and {Cu}(110) {Surfaces}}, year = {2023} } @article{faucris.298890331, abstract = {We studied the adsorption and reaction behavior of the ionic liquid (IL) 1,3-dimethylimidazolium bis[(trifluoromethyl)sulfonyl]imide ([C(1)C(1)Im][Tf2N]) on Cu(111) using non-contact atomic force microscopy (nc-AFM), scanning tunneling microscopy (STM), and angle-resolved X-ray photoelectron spectroscopy (ARXPS) in ultrahigh vacuum as a function of temperature, supported by density-functional theory (DFT) calculations. Our nc-AFM results for sub-monolayer IL films show that at 200 K, the IL self-assembles into highly ordered islands, with cations and anions arranged next to each other in a checkerboard-type phase. After extended annealing at 300 K, the structure transforms first to a hexagonal phase and then to a porous honeycomb phase. Simultaneously, many small, disordered islands are formed. Complementary ARXPS reveals no IL desorption until 300 K. However, a significant fraction of the IL is converted to a new species as deduced from new, strongly shifted peaks that develop in the XP spectra at around 275 K and grow with annealing time at 300 K. We correlate the remaining unshifted peaks to the ordered phases observed in nc-AFM and the shifted peaks to decomposition products, which appear as disordered islands in nc-AFM and STM. Upon further heating to 360 K, about 50% of the anions or their decomposition products desorb from the surface, while cation-related fragments mostly remain on the surface. From DFT, we obtain additional information on the structure of the ordered phases and the interaction of the IL with the substrate.}, author = {Adhikari, Rajan and Massicot, Stephen and Fromm, Lukas and Talwar, Timo and Gezmis, Emine and Meusel, Manuel and Bayer, Andreas and Jaekel, Simon and Maier, Florian and Görling, Andreas and Steinrück, Hans-Peter}, doi = {10.1007/s11244-023-01801-y}, faupublication = {yes}, journal = {Topics in Catalysis}, note = {CRIS-Team WoS Importer:2023-05-05}, peerreviewed = {Yes}, title = {{Structure} and {Reactivity} of the {Ionic} {Liquid} [{C}(1){C}(1){Im}][{Tf2N}] on {Cu}(111)}, year = {2023} } @article{faucris.304993489, abstract = {We present an ARXPS study on the surface composition and interfacial behavior of commercial [Rh(COD)<inf>2</inf>][TfO] in [C<inf>2</inf>C<inf>1</inf>Im][TfO], [C<inf>4</inf>C<inf>1</inf>Im][TfO], [C<inf>8</inf>C<inf>1</inf>Im][TfO], and [C<inf>2</inf>C<inf>1</inf>Im][EtOSO<inf>3</inf>]. The complex was found to be non-intact in a solution of these ILs through the loss of COD ligands, accompanied by the depletion of the metal center from the IL/vacuum interface. Increasing the chain length of the aliphatic substituent on the imidazolium cation of the [TfO]⁻-based ILs led to a more pronounced depletion from the interface, due to the higher surface affinity of the solvent cations with the longer alkyl chains. The loss of COD ligands offered facile in situ ligand substitution with surface-active TPPTS to afford a moderate increase in the surface concentration of Rh. We propose the formation of a Schrock−Osborn-type catalyst [Rh(COD)(TPPTS)<inf>2</inf>][TfO]. Information on the surface composition and targeted design of the gas/IL interface is highly relevant for applications in IL-based catalytic systems, such as in supported ionic liquid phase (SILP) catalysis.}, author = {Hemmeter, Daniel and Paap, Ulrike and Maier, Florian and Steinrück, Hans-Peter}, doi = {10.3390/catal13050871}, faupublication = {yes}, journal = {Catalysts}, keywords = {catalysis; ionic liquids; rhodium catalysts; surface analysis; X-ray photoelectron spectroscopy (XPS)}, note = {CRIS-Team Scopus Importer:2023-06-09}, peerreviewed = {Yes}, title = {{Structure} and {Surface} {Behavior} of {Rh} {Complexes} in {Ionic} {Liquids} {Studied} {Using} {Angle}-{Resolved} {X}-ray {Photoelectron} {Spectroscopy}}, volume = {13}, year = {2023} } @article{faucris.123159124, abstract = {Scanning tunnelling microscopy (STM) enables us to directly observe the dynamic behaviour of organic molecules on surfaces. White imaging atoms and molecules using STM is certainly fascinating by itself, corresponding temperature-dependent measurements allow for the quantitative determination of the energetics and kinetics of the underlying molecular surface processes. Herein, we review recent advances in the STM investigation of the dynamic behaviour of adsorbed porphyrins at and close to room temperature. Three different case studies are discussed, providing insight into the dynamics of diffusion, rotation, reaction, and molecular switching at surfaces, based on isothermal STM measurements. The reviewed examples demonstrate that variable temperature STM can be a suitable toot to directly monitor the dynamic behaviour of individual adsorbed molecules, at and close to room temperature. Free base porphyrins on Cu(111) proved to be particularly suitable for these studies due to the strong bonding interaction between the iminic nitrogen atoms in the porphyrin macrocycle and the Cu substrate atoms. As a consequence, the corresponding activation energies for surface diffusion, self-metalation reaction and conformational switching are of a magnitude that allows for monitoring the processes at and around room temperature, in contrast to most previous studies, which were performed at cryogenic temperatures. The kinetic analysis of the surface diffusion and setf-metalation was performed using an Arrhenius approach, yielding the corresponding activation energies and preexponential factors. In contrast, the conformational switching process was analysed in the framework of transition state theory, based on the Eyring equation. This approach provides a more detailed insight into interpretable thermodynamic potentials, i.e., the enthalpic and entropic contributions to the activation barrier. The analysis shows that at room temperature the adsorption and switching behaviour of the investigated free base porphyrin on Cu(111) is dominated by entropic effects. Since the entropic energy contribution vanishes at low temperatures, the importance of experiments conducted at temperatures close to room temperature is emphasized.}, author = {Marbach, Hubertus and Steinrück, Hans-Peter}, doi = {10.1039/c4cc01744g}, faupublication = {yes}, journal = {Chemical Communications}, pages = {9034-9048}, peerreviewed = {Yes}, title = {{Studying} the dynamic behaviour of porphyrins as prototype functional molecules by scanning tunnelling microscopy close to room temperature}, volume = {50}, year = {2014} } @article{faucris.107836124, abstract = {Sorting molecules: Effective phase separation of two porphyrin species, namely CoTPP and 2HTPP (TPP= tetraphenylporphyrin, 2HTPP=2H- tetraphenylporphyrin), on Cu(111) is reported. The separation process can be conclusively explained by the domination of molecule-molecule interactions for CoTPP, whereas the adsorption behavior of 2HTPP is dominated by molecule-substrate interactions (see figure). Copyright &copy; 2011 WILEY-VCH Verlag GmbH &amp; Co. KGaA, Weinheim.}, author = {Buchner, Florian and Zillner, Elisabeth and Röckert, Michael and Gläßel, Stefanie and Steinrück, Hans-Peter and Marbach, Hubertus}, doi = {10.1002/chem.201100462}, faupublication = {yes}, journal = {Chemistry - A European Journal}, pages = {10226-10229}, peerreviewed = {Yes}, title = {{Substrate}-mediated phase separation of two porphyrin derivatives on {Cu}(111)}, volume = {17}, year = {2011} } @article{faucris.210453149, abstract = {Nanocluster arrays grown on a graphene Moire on Rh(1 1 1) are an excellent model system that can bridge the materials gap between single crystals and real catalysts. They feature different adsorption sites like edges, kinks, and facets, but are at the same time well-ordered with a small size distribution. Herein, we used platinum nanocluster arrays to investigate the oxidation of sulfur, which is a common catalyst poison, as a possible route to restore the catalyst. We studied the kinetics in a site-resolved manner with high-resolution XPS, despite the complex shape of the nanoparticles. Since SO3 and SO4 were the only observable SOx surface species, the reaction of S to SO was identified as the rate-determining step. As a secondary process, the displacement of sulfur from edge to facet sites caused by oxygen was observed.}, author = {Düll, Fabian and Schwaab, Valentin and Späth, Florian and Bauer, Udo and Bachmann, Philipp and Steinhauer, Johann and Steinrück, Hans-Peter and Papp, Christian}, doi = {10.1016/j.cplett.2018.08.026}, faupublication = {yes}, journal = {Chemical Physics Letters}, pages = {165-169}, peerreviewed = {Yes}, title = {{Sulfur} oxidation on graphene-supported platinum nanocluster arrays}, volume = {708}, year = {2018} } @article{faucris.108289544, abstract = {Steps in the right direction: The role of steps in the removal of sulfur from a Pt model catalyst via metastable SO and SO species, was demonstrated by in situ high-resolution X-ray photoelectron spectroscopy. From isothermal experiments the activation energy of the rate-determining step was deduced to be 34 kJmol. &copy; 2009 Wiley-VCH Verlag GmbH &amp;. Co. KGaA.}, author = {Streber, Regine and Papp, Christian and Lorenz, Michael Peter Andreas and Bayer, Andreas and Denecke, Reinhard and Steinrück, Hans-Peter}, doi = {10.1002/anie.200904488}, faupublication = {yes}, journal = {Angewandte Chemie International Edition}, pages = {9743-9746}, peerreviewed = {Yes}, title = {{Sulfur} oxidation on {Pt}(355): {It} is the steps!}, volume = {48}, year = {2009} } @article{faucris.108484464, abstract = {The adsorption of SO on Ni(110) has been studied in detail by temperature programmed desorption (TPD), low energy electron diffraction (LEED), X-ray photoelectron spectroscopy (XPS), and angle resolved UV photoelectron spectroscopy (ARUPS) using linearly polarized synchrotron radiation. At 100 K SO is found to chemisorb in molecular form on Ni(110) with a saturation coverage of 0.5 ML (1 ML = 1 molecule Ni-atom). The saturated chemisorbed layer exhibits a c(2 &times; 2) LEED pattern. At initial coverages below 0.25 ML, SO completely decomposes upon heating to 750 K; for higher coverages molecular SO desorption is also observed in a single peak between 300 and 400 K. From the angle resolved UPS spectra and symmetry selection rules we deduce the symmetry of the adsorbed SO molecules for low coverages as C (&sigma;), with the molecular O-S-O plane oriented perpendicular to the surface and aligned along the [001] azimuth (perpendicular to the close-packed substrate rows). Within the plane the molecule is tilted, which is attributed to an additional Ni-O interaction. In the saturated layer the symmetry is further reduced to C indicating an additional tilting and/or rotation of the molecular plane with respect to the substrate. &copy; 1993.}, author = {Zebisch, P. and Weinelt, M. and Steinrück, Hans-Peter}, faupublication = {no}, journal = {Surface Science}, pages = {295-305}, peerreviewed = {Yes}, title = {{Sulphur} dioxide adsorption on the {Ni}(110) surface}, url = {https://www.scopus.com/record/display.uri?eid=2-s2.0-0027678739&origin=inward}, volume = {295}, year = {1993} } @article{faucris.321091896, abstract = {The research and optimization of catalysts are instrumental in revolutionizing chemical processes and making them viable in terms of energy and resources. Supported catalytically active liquid metal solutions (SCALMS) are highly active and stable in the harsh environment of the dehydrogenation reaction of alkanes. This is attributed to their liquid and dynamic nature and their isolated catalytically active single-atom sites. SCALMS consists of a liquid metal matrix (gallium) in which a catalytically active transition metal (platinum, rhodium, palladium, or nickel) is dissolved. Binary SCALMS systems are the subject of extensive research, aiming at a better understanding for achieving optimal performance. This work uses a combined multidisciplinary approach to examine ternary systems of the active transition metal platinum with mixtures of gallium with either tin or indium. Reaction engineering and surface chemical analysis by X-ray photoelectron spectroscopy are combined with density functional theory (DFT) and machine learning force field (ML-FF) simulations. Introducing a third metal into the mixture alters the reactivity, surface composition, and concentration gradient in the liquid metal catalyst. We demonstrate that changes in catalytic reactivity correlate with changes in the surface concentration of the active transition metal platinum and of the position of the d-band center. These findings hold great promise for future research directions as they offer potential starting points for developing SCALMS systems.}, author = {Moritz, Michael and Maisel, Sven and Raman, Narayanan and Wittkämper, Haiko and Wichmann, Christoph and Grabau, Mathias and Kahraman, Deniz and Steffen, Julien and Taccardi, Nicola and Görling, Andreas and Haumann, Marco and Wasserscheid, Peter and Steinrück, Hans-Peter and Papp, Christian}, doi = {10.1021/acscatal.4c01282}, faupublication = {yes}, journal = {ACS Catalysis}, keywords = {AIMD; dehydrogenation; DFT; ML-FF; single-atom catalysis; XPS}, note = {CRIS-Team Scopus Importer:2024-04-19}, pages = {6440-6450}, peerreviewed = {Yes}, title = {{Supported} {Catalytically} {Active} {Liquid} {Metal} {Solutions}: {Liquid} {Metal} {Catalysis} with {Ternary} {Alloys}, {Enhancing} {Activity} in {Propane} {Dehydrogenation}}, volume = {14}, year = {2024} } @inproceedings{faucris.230326354, author = {Taccardi, Nicola and Grabau, Mathias and Debuschewltz, Jonas and Distaso, Monica and Brandl, Marco and Hock, Rainer and Maier, Florian and Papp, Christian and Erhard, Jannis and Neiß, Christian and Peukert, Wolfgang and Görling, Andreas and Wolf, Moritz and Haumann, Marco and Steinrück, Hans-Peter and Wasserscheid, Peter}, booktitle = {12th Natural Gas Conversion Symposium 2019}, date = {2019-06-02/2019-06-06}, faupublication = {yes}, isbn = {9781510888883}, note = {CRIS-Team Scopus Importer:2019-12-10}, pages = {353-354}, peerreviewed = {unknown}, publisher = {AIChE}, title = {{Supported} liquid metals - {A} new class of robust dehydrogenation catalysts}, venue = {San Antonio, TX}, year = {2019} } @article{faucris.107144444, abstract = {The adsorption of 2H-tetraphenylporphycene (2HTPPc) on Cu(111) was investigated by scanning tunneling microscopy (STM). At medium coverages, supramolecular ordered islands are observed. The individual 2HTPPc molecules appear as two pairs of intense protrusions which are separated by an elongated depression. In the islands, the molecules are organized in rows oriented along one of the close packed Cu(111) substrate rows; the structure is stabilized by T-type interactions of the phenyl substituents of neighboring molecules. Two types of rows are observed, namely, highly ordered rows in which all molecules exhibit the same orientation, and less ordered rows in which the molecules exhibit two perpendicular orientations. Altogether, three different azimuthal orientations of 2HTPPc are observed within one domain, all of them rotated by 15&deg; $\pm$ 1&deg; relative to one closed packed Cu direction. The highly ordered rows are always separated by either one or two less ordered rows, with the latter structure being the thermodynamically more stable one. The situation in the islands is highly dynamic, such that molecules in the less ordered rows occasionally change orientation, also complete highly ordered rows can move. The supramolecular order and structural dynamics are discussed on the basis of the specific molecule-substrate and molecule-molecule interactions.}, author = {Stark, Michael Werner and Träg, Johannes and Ditze, Stefanie and Brenner, Wolfgang and Jux, Norbert and Steinrück, Hans-Peter and Marbach, Hubertus}, doi = {10.1063/1.4908268}, faupublication = {yes}, journal = {Journal of Chemical Physics}, pages = {101925}, peerreviewed = {Yes}, title = {{Supramolecular} order and structural dynamics: {A} {STM} study of {2H}-tetraphenylporphycene on {Cu}(111)}, volume = {142}, year = {2015} } @article{faucris.108300544, abstract = {We have investigated the surface composition of Pd/ZnO catalysts dispersed on micro-channeled Al-foils in a non-activated and in the activated state, between 300 and 700 K using X-ray photoelectron spectroscopy (XPS). While the surface of the non-activated catalyst, as obtained after calcination, is composed of PdO, the surface of the activated (reduced) catalyst consists of predominantly PdZn and &sim;30% metallic Pd. When increasing the temperature up to 700 K in UHV significant structural surface changes were observed for both samples. For the non-activated sample, PdO was reduced mainly to the Pd metal with some fraction of PdZn alloy. For the activated catalyst, the fraction of metallic Pd was also converted to PdZn, yielding a pure alloy, which is stable to at least 600 K. At 700 K both samples show changes due to segregation of Mg from the micro-channeled Al-foils onto which the powdered catalysts were deposited, which contains 3% Mg. &copy; 2008 Elsevier B.V. All rights reserved.}, author = {Dumbuya, K. and Denecke, Reinhard and Steinrück, Hans-Peter}, doi = {10.1016/j.apcata.2008.06.037}, faupublication = {yes}, journal = {Applied Catalysis A-General}, pages = {209-213}, peerreviewed = {Yes}, title = {{Surface} analysis of {Pd}/{ZnO} catalysts dispersed on micro-channeled {Al}-foils by {XPS}}, volume = {348}, year = {2008} } @article{faucris.211823604, abstract = {We report on surface investigations of cesium and tetraphenylphosphonium bis(trifluoromethylsulfonyl)imide (Cs[Tf2N], [PPh4][Tf2N]) molten salts and their mixtures. Depending on composition, these ionic compounds combine low melting points with exceptionally high thermal stability, and thus, exhibit considerably enlarged thermal operation windows compared to conventional ionic liquids. To elucidate their liquid-solid transition behavior in the near-surface region, temperature-dependent angle-resolved X-ray photoelectron spectroscopy (ARXPS) investigations were performed using our unique laboratory electron spectrometer DASSA ("Dual Analyzer System for Surface Analysis"), dedicated for investigations of macroscopic liquid samples. We followed temperature-induced changes in bulk and surface composition within the first nanometers of the neat salt melts and of Cs[Tf2N]: (PPh4][Tf2N]= 3 : 1 and 1 : 3 mixtures. In the mixtures, pronounced surface enrichment of Cs+ on expense of the bulky [PPne ions was found in the liquid state at temperatures close to the liquid-solid transition. In the solid state of Cs[Tf2N]-rich mixtures, [PPH4](+) completely vanishes from the near-surface region probed by XPS. (C) 2018 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY license.}, author = {Bhuin, Radha Gobinda and Schreiber, Patrick and Heller, Bettina and Scheuermeyer, Marlene and Wasserscheid, Peter and Steinrück, Hans-Peter and Maier, Florian}, doi = {10.1016/j.molliq.2018.11.056}, faupublication = {yes}, journal = {Journal of Molecular Liquids}, note = {CRIS-Team WoS Importer:2019-02-27}, pages = {290-296}, peerreviewed = {Yes}, title = {{Surface} behavior of low-temperature molten salt mixtures during the transition from liquid to solid}, volume = {275}, year = {2019} } @article{faucris.108302744, abstract = {The surface composition of oligo(ethylene glycol) ether functionalized bis(trifluoromethylsulfonyl)imide ionic liquids has been studied by means of X-ray photoelectron spectroscopy (XPS). For [Me(EG)MIM] [TfN], [Et(EG)MIM]-[TfN], and [Me(EG)MIM][Tf N], which vary by the number of ethylene glycol (EG) units (from 1 to 3), we have shown that the stoichiometry of the surface near region is in excellent agreement with the bulk stoichiometry, which confirms the high purity of the ionic liquid samples investigated and rules out pronounced surface orientation effects. This has been deduced from the experimental observation that the angle-resolved XP spectra of all elements present in the IL anions and cations (C, N, O, F, S) show identical signals in the bulk and surfaces sensitive geometry, i.e., at 0&deg; and 70&deg; emission angle, respectively. The relative intensity ratios of all elements were found to be in nearly perfect agreement with the nominal values for the individual ILs. In contrast to these findings, we identified surfaceactive impurities in [Me(EG)MIM]I, which is the starting material for the final anion exchange step to synthesize [Me(EG)MIM][Tf2N]. Sputtering of the surface led to a depletion of this layer, which however recovered with time. The buildup of this contamination is attributed to a surface enrichment of a minor bulk contamination that shows surface activity in the iodide melt. &copy; 2008 American Chemical Society.}, author = {Kolbeck, Claudia and Killian, Manuela and Maier, Florian and Paape, Natalia and Wasserscheid, Peter and Steinrück, Hans-Peter}, doi = {10.1021/la801261h}, faupublication = {yes}, journal = {Langmuir}, pages = {9500-9507}, peerreviewed = {Yes}, title = {{Surface} characterization of functionalized imidazolium-based ionic liquids}, volume = {24}, year = {2008} } @article{faucris.218978599, abstract = {Dwindling fossil fuels force humanity to search for new energy production routes. Besides energy generation, its storage is a crucial aspect. One promising approach is to store energy from the sun chemically in strained organic molecules, so-called molecular solar thermal (MOST) systems, which can release the stored energy catalytically. A prototypical MOST system is norbornadiene/quadricyclane (NBD/QC) whose energy release and surface chemistry need to be understood. Besides important key parameters such as molecular weight, endergonic reaction profiles, and sufficient quantum yields, the position of the absorption onset of NBD is crucial to cover preferably a large range of sunlight's spectrum. For this purpose, one typically derivatizes NBD with electron-donating and/or electron-accepting substituents. To keep the model system simple enough to be investigated with photoemission techniques, we introduced bromine atoms at the 2,3-position of both compounds. We study the adsorption behavior, energy release, and surface chemistry on Ni(111) using high-resolution X-ray photoelectron spectroscopy (HR-XPS), UV photoelectron spectroscopy, and density functional theory calculations. Both Br 2 -NBD and Br 2 -QC partially dissociate on the surface at ∼120 K, with Br 2 -QC being more stable. Several stable adsorption geometries for intact and dissociated species were calculated, and the most stable structures are determined for both molecules. By temperature-programmed HR-XPS, we were able to observe the conversion of Br 2 -QC to Br 2 -NBD in situ at 170 K. The decomposition of Br 2 -NBD starts at 190 K when C-Br bond cleavage occurs and benzene and methylidene are formed. For Br 2 -QC, the cleavage already occurs at 130 K when cycloreversion to Br 2 -NBD sets in.}, author = {Bauer, Udo and Fromm, Lukas and Weiß, Cornelius and Späth, Florian and Bachmann, Philipp and Düll, Fabian and Steinhauer, Johann and Matysik, Sabine and Pominov, Arkadii and Görling, Andreas and Hirsch, Andreas and Steinrück, Hans-Peter and Papp, Christian}, doi = {10.1063/1.5095583}, faupublication = {yes}, journal = {Journal of Chemical Physics}, note = {CRIS-Team Scopus Importer:2019-05-28}, peerreviewed = {Yes}, title = {{Surface} chemistry of 2,3-dibromosubstituted norbornadiene/quadricyclane as molecular solar thermal energy storage system on {Ni}(111)}, volume = {150}, year = {2019} } @article{faucris.322287911, abstract = {The concept of a solid catalyst with an ionic liquid layer (SCILL) is a promising approach to improve the selectivity of noble metal catalysts in heterogeneous reactions. In order to understand the origins of this selectivity control, we investigated the growth and thermal stability of ultrathin 1-ethyl-3-methylimidazolium trifluormethanesulfonate [C<inf>2</inf>C<inf>1</inf>Im][OTf] films on Pt(111) by infrared reflection absorption spectroscopy (IRAS) and X-ray photoelectron spectroscopy (XPS) in time-resolved and temperature-programmed experiments. We combined these spectroscopy experiments with scanning tunneling microscopy (STM) to obtain detailed insights into the orientation and adsorption geometry of the ions in the first IL layer. Furthermore, we propose a mechanism for the thermal evolution of [C<inf>2</inf>C<inf>1</inf>Im][OTf] on Pt(111). We observe an intact IL layer on the surface at temperatures below 200 K. Adsorbed [C<inf>2</inf>C<inf>1</inf>Im][OTf] forms islands, which are evenly distributed over the surface. The [OTf]⁻ anion adsorbs via the SO<inf>3</inf> group, with the molecular axis perpendicular to the surface. Anions and cations are arranged next to each other, alternating on the Pt(111) surface. Upon heating to 250 K, we observe changes in geometry and structural distribution. Whereas at low temperature, the ions are arranged alternately for electrostatic reasons, this driving force is no longer decisive at 250 K. Here, a phase separation of two different species is discernible in STM. We propose that this effect is due to a surface reaction, which changes the charge of the adsorbates. We assume that the IL starts to decompose at around 250 K, and thus, pristine IL and decomposition products coexist on the surface. Also, IRAS and XPS show indication of IL decomposition. Further heating leads to increased IL decomposition. The reaction products associated with the anions are volatile and leave the surface. In contrast, the cation fragments remain on the surface up to temperatures above 420 K.}, author = {Bühlmeyer, Hanna and Talwar, Timo and Eschenbacher, Roman and Barreto, Jade and Hauner, Jonas and Knörr, Lukas and Steinrück, Hans-Peter and Maier, Florian and Libuda, Jörg}, doi = {10.1021/acsami.4c02239}, faupublication = {yes}, journal = {ACS Applied Materials and Interfaces}, keywords = {infrared reflection absorption spectroscopy; ionic liquids; Pt(111); scanning tunneling microscopy; SCILL; X-ray photoelectron spectroscopy}, note = {CRIS-Team Scopus Importer:2024-05-10}, peerreviewed = {Yes}, title = {{Surface} {Chemistry} of a [{C2C1Im}][{OTf}] ({Sub}){Wetting} {Layer} on {Pt}(111): {A} {Combined} {XPS}, {IRAS}, and {STM} {Study}}, year = {2024} } @article{faucris.277569036, abstract = {Molecular solar thermal (MOST) systems are a promising approach for the introduction of sustainable energy storage solutions. We investigated the feasibility of the dicyano-substituted norbornadiene/quadricyclane molecule pair on Ni(111) for catalytic model studies. This derivatization is known to lead to a desired bathochromic shift of the absorption maximum of the parent compound. In our experiments further favorable properties were found: At low temperatures, both molecules adsorb intact without any dissociation. In situ temperature-programmed HR-XPS experiments reveal the conversion of (CN)(2)-quadricyclane to (CN)(2)-norbornadiene under energy release between 175 and 260 K. The absence of other surface species due to side reactions indicates full isomerization. Further heating leads to the decomposition of the molecular framework into smaller carbonaceous fragments above 290 K and finally to amorphous structures, carbide and nitride above 400 K. DFT calculations gave insights into the adsorption geometries. (CN)(2)-norbornadiene is expected to interact stronger with the surface, with flat configurations being favorable. (CN)(2)-quadricyclane exhibits smaller adsorption energies with negligible differences for flat and side-on geometries. Simulated XP spectra are in good agreement with experimental findings further supporting the specific spectroscopic fingerprints for both valence isomers.}, author = {Hemauer, Felix and Bauer, Udo and Fromm, Lukas and Weiß, Cornelius and Leng, Andreas and Bachmann, Philipp and Düll, Fabian and Steinhauer, Johann and Schwaab, Valentin and Grzonka, Robert and Hirsch, Andreas and Görling, Andreas and Steinrück, Hans-Peter and Papp, Christian}, doi = {10.1002/cphc.202200199}, faupublication = {yes}, journal = {ChemPhysChem}, note = {CRIS-Team WoS Importer:2022-07-08}, peerreviewed = {Yes}, title = {{Surface} {Chemistry} of the {Molecular} {Solar} {Thermal} {Energy} {Storage} {System} 2,3-{Dicyano}-{Norbornadiene}/{Quadricyclane} on {Ni}(111)}, year = {2022} } @article{faucris.113296964, abstract = {We report the first example of a surface-confined two-step synthesis of axially coordinated metalloporphyrin complexes in an ultrahigh vacuum environment. Specifically, a monolayer of tetraphenylporphyrin on an Ag(111) surface was metalated with coadsorbed Zn atoms, and thereafter, NH ligands were attached to the metal centers. The surface reactions were monitored with X-ray photoelectron spectroscopy. The approach outlined in this work can be employed to produce and study adsorbates of various axially coordinated porphyrin complexes, including biologically relevant systems. &copy; 2007 American Chemical Society.}, author = {Flechtner, Ken and Kretschmann, Andreas and Bradshaw, Liam R. and Walz, Marie-Madeleine and Steinrück, Hans-Peter and Gottfried, Michael}, doi = {10.1021/jp071531d}, faupublication = {yes}, journal = {Journal of Physical Chemistry C}, pages = {5821-5824}, peerreviewed = {Yes}, title = {{Surface}-confined two-step synthesis of the complex (ammine)(meso- tetraphenylporphyrinato)-zinc({II}) on {Ag}(111)}, volume = {111}, year = {2007} } @article{faucris.108390524, abstract = {(Graph Presented) Surfaces of ionic liquids: Angle-dependent X-ray photoelectron spectroscopy (XPS) shows that the surface composition of a solution of [Pt(NH)]Cl in the ionic liquid 1-ethyl-3-methylimidazolium ethyl sulfate ([EMIM][EtOSO]) deviates considerably from the bulk composition. The [Pt-(NH) ] cation is enriched on the surface at the expense of the [EMIM] cation (see picture), while the Cl anion is depleted to below the XPS detection limit. &copy; 2006 Wiley-VCH Verlag GmbH &amp; Co. KGaA.}, author = {Maier, Florian and Gottfried, Michael and Rossa, Jürgen and Gerhard, Dirk and Schulz, Peter and Schwieger, Wilhelm and Wasserscheid, Peter and Steinrück, Hans-Peter}, doi = {10.1002/anie.200602756}, faupublication = {yes}, journal = {Angewandte Chemie International Edition}, pages = {7778-7780}, peerreviewed = {Yes}, title = {{Surface} enrichment and depletion effects of ions dissolved in an ionic liquid: {An} {X}-ray photoelectron spectroscopy study}, volume = {45}, year = {2006} } @article{faucris.202405567, author = {Heller, Bettina and Kolbeck, Claudia and Niedermaier, Inga and Dommer, Sabine and Schatz, Jürgen and Hunt, Patricia and Maier, Florian and Steinrück, Hans-Peter}, doi = {10.1002/cphc.201800216}, faupublication = {yes}, journal = {ChemPhysChem}, keywords = {density functional theory; electronic structure; angle-resolved X-ray photoelectron spectroscopy (ARXPS); ionic liquid mixture; surface science}, pages = {1733-1745}, peerreviewed = {Yes}, title = {{Surface} {Enrichment} in {Equimolar} {Mixtures} of {Non}-{Functionalized} and {Functionalized} {Imidazolium}-{Based} {Ionic} {Liquids}}, volume = {19}, year = {2018} } @article{faucris.201791821, abstract = {<table><tbody><tr><td width="550">For equimolar mixtures of ionic liquids with imidazolium-based<br />cations of very different electronic structure, we observe very<br />pronounced surface enrichment effects by angle-resolved X-ray<br />photoelectron spectroscopy (XPS). For a mixture with the same<br />anion, that is, 1-methyl-3-octylimidazolium hexafluorophos<br />phate+1,3-di(methoxy)imidazolium hexafluorophosphate<br />([C8C1Im][PF6]+[(MeO)2Im][PF6]), we find a strong enrichment of<br />the octyl chain-containing [C8C1Im]+ cation and a correspond<br />ing depletion of the [(MeO)2Im]+ cation in the topmost layer.<br />For a mixture with different cations and anions, that is, [C8C1Im]<br />[Tf2N]+[(MeO)2Im][PF6], we find both surface enrichment of the<br /><table><tbody><tr><td width="550">[C8C1Im]+ cation and the [Tf2N]@ (bis[(trifluoromethyl)sulfonyl]<br />imide) anion, while [(MeO)2Im]+ and [PF6]@ are depleted from<br />the surface. We propose that the observed behavior in these<br />mixtures is due to a lowering of the surface tension by the<br />enriched components. Interestingly, we observe pronounced<br />differences in the chemical shifts of the imidazolium ring signals<br />of the [(MeO)2Im]+ cations as compared to the non-functional<br />ized cations. Calculations of the electronic structure and the<br />intramolecular partial charge distribution of the cations contrib<br />ute to interpreting these shifts for the two different cations.</td></tr></tbody></table> <br /><br /></td></tr></tbody></table> <br />}, author = {Heller, Bettina and Kolbeck, Claudia and Niedermaier, Inga and Dommer, Sabine and Schatz, Jürgen and Hunt, Patricia and Maier, Florian and Steinrück, Hans-Peter}, doi = {10.1002/cphc.201800216}, faupublication = {yes}, journal = {ChemPhysChem}, pages = {1733-1745}, peerreviewed = {Yes}, title = {{Surface} {Enrichment} in {Equimolar} {Mixtures} of {Non}-{Functionalized} and {Functionalized} {Imidazolium}-{Based} {Ionic} {Liquids}}, volume = {19}, year = {2018} } @article{faucris.117547144, abstract = {The formation of surface GaO films on liquid samples of Ga, and Pt-Ga alloys with 0.7 and 1.8 at.% Pt was examined using near-ambient pressure (NAP) X-ray photoelectron spectroscopy (XPS). Thickness, composition and growth of the oxide films were deduced as a function of temperature and Pt content of the alloys, in ultra-high vacuum and at oxygen pressures of 3 &times; 10, 3 &times; 10 and 1 mbar. We examined oxide layers up to a thickness of 37 &Aring;. Different growth modes were found for oxidation at low and high pressures. The formed GaO oxide films showed an increased Pt content, while the pristine GaPt alloy showed a surface depletion of Pt at the examined temperatures. Upon growth of GaO on Pt/Ga alloys a linear increase of Pt content was observed, due to the incorporation of 3.6 at.% Pt in the GaO. The Pt content in GaO, at the examined temperatures and bulk Pt concentrations is found to be independent of pressure, temperature and the nominal Pt content of the metallic alloy.}, author = {Grabau, Mathias and Krick Calderon, Sandra and Rietzler, Florian and Niedermaier, Inga and Taccardi, Nicola and Wasserscheid, Peter and Maier, Florian and Steinrück, Hans-Peter and Papp, Christian}, doi = {10.1016/j.susc.2016.03.009}, faupublication = {yes}, journal = {Surface Science}, keywords = {Bimetallic catalysts; Gallium oxide; NAP XPS; Pt/Ga alloys}, pages = {16-21}, peerreviewed = {Yes}, title = {{Surface} enrichment of {Pt} in {Ga2O3} films grown on liquid {Pt}/{Ga} alloys}, volume = {651}, year = {2016} } @article{faucris.110440264, abstract = {We demonstrate that a thermodynamic. complex equilibrium within an ionic liquid film can be significantly influenced by the presence of the liquid-vacuum interface. Using surface sensitive X-ray photoelectron spectroscopy, we find that the temperature-driven transition from the blue-colored tetrahedral [Co(II) (NCS)(4)](2-) to the red-colored octahedral [Co(II) (NCS)(6)](4-) complex already occurs within the outermost nanometers at around +4 degrees C as compared with -25 degrees C in the bulk. This thermochromic transformation in the near-surface region goes along with a loss in preferential surface orientation of free [SCN](-) anions and with a pronounced decrease in the complex density; both effects are attributed to the formation of a weakly bound solvation shell around the [Co(II) (NCS)(6)](4-) anion, leading to an effective complex dilution. Our results are not only relevant for high-surface area thin film systems, such as in sensor and catalysis applications, but also shed light on the role of ionic liquid surfaces in particular and liquid surfaces in general.}, author = {May, Benjamin and Hoenle, Michael and Heller, Bettina and Greco, Francesco and Bhuin, Radha Gobinda and Steinrück, Hans-Peter and Maier, Florian}, doi = {10.1021/acs.jpclett.7b00142}, faupublication = {yes}, journal = {Journal of Physical Chemistry Letters}, pages = {1137-1141}, peerreviewed = {Yes}, title = {{Surface}-{Induced} {Changes} in the {Thermochromic} {Transformation} of an {Ionic} {Liquid} {Cobalt} {Thiocyanate} {Complex}}, volume = {8}, year = {2017} } @article{faucris.262428661, abstract = {We have examined model systems for the recently reported Pd-Ga Supported Catalytically Active Liquid Metal Solutions (SCALMS) catalysts using near-ambient pressure X-ray photoelectron spectroscopy (NAP-XPS) under oxidizing conditions. Gallium is known to be highly prone to oxidation and in practical applications, handling of the catalyst material in air or the presence of traces of oxygen in the reactor are unavoidable. Therefore, we expect our results to be of high relevance for the application of Ga-based SCALMS catalysts. Pd-Ga alloy samples of 1.3 and 1.8 at% Pd content were exposed to molecular oxygen at different pressures between 3 x 10(-7) and 1 mbar and a temperature of 550 K. We observe the formation of wetting Ga2O3 films upon exposure to molecular oxygen. The absolute thicknesses of the oxide films depend on oxygen pressure, with values ranging from similar to 12 angstrom at 10(-7) to 10(-5) mbar to similar to 50 angstrom at 1 mbar. The formed metal-oxide interface leads to a redistribution of Pd, which accumulates at the boundary between the wetting oxide film and the metal substrate as a response to the oxide film growth. A maximum Pd 3d intensity is observed at an oxide thickness of 5 angstrom. For thicker films, the Pd 3d signal and the Ga 3d signal ascribed to the metallic substrate decrease in parallel, which is attributed to the oxide layer growing on top of the liquid metal alloy. From this observation, we conclude that no significant amount of Pd is bound in the newly formed oxide film. Density-functional theory (DFT) calculations support the experimental observations.}, author = {Wittkämper, Haiko and Maisel, Sven and Moritz, Michael and Grabau, Mathias and Görling, Andreas and Steinrück, Hans-Peter and Papp, Christian}, doi = {10.1039/d1cp02458b}, faupublication = {yes}, journal = {Physical Chemistry Chemical Physics}, note = {CRIS-Team WoS Importer:2021-08-06}, peerreviewed = {Yes}, title = {{Surface} oxidation-induced restructuring of liquid {Pd}-{Ga} {SCALMS} model catalysts}, year = {2021} } @article{faucris.107837004, abstract = {The formation of poly(p-phenylene-terephthalamide) (PPTA) by surface-assisted polymerization of terephthaloyl chloride (TPC) and p-phenylenediamine (PPD) on Ag(111) has been studied by X-ray photoelectron spectroscopy (XPS) and scanning tunneling microscopy (STM). Analysis of the XPS data reveals that the polymer is formed in the (sub-) monolayer regime already at room temperature. Upon vacuum deposition of TPC onto the single-crystal surface, the carbon-chlorine bond is cleaved, and the polymerization proceeds via a p-phenylene dicarbonyl species, which is presumably surface stabilized. This contrasts the reaction mechanism in solution, where the chlorine atom is expelled after a nucleophilic attack by the amine group. Annealing of the sample leads to desorption of residual PPD monomers, lateral ordering of the polymer chains, and further progress of the polymerization that can be followed by XPS. The chain length distribution of the polyamide, as extracted from the XP spectra, is consistent with the typical chain lengths found in STM images. &copy; 2011 American Chemical Society.}, author = {Schmitz, Christoph H. and Schmid, Martin and Gärtner, Stefan and Steinrück, Hans-Peter and Gottfried, Michael and Sokolowski, Moritz}, doi = {10.1021/jp202986r}, faupublication = {yes}, journal = {Journal of Physical Chemistry C}, pages = {18186-18194}, peerreviewed = {Yes}, title = {{Surface} polymerization of poly(p -phenylene-terephthalamide) on {Ag}(111) investigated by {X}-ray photoelectron spectroscopy and scanning tunneling microscopy}, volume = {115}, year = {2011} } @article{faucris.121554224, abstract = {Controlling the metalation of surface porphyrins is a critical process in porphyrin-based devices. Indeed, surface porphyrins are known to metalate in ultrahigh vacuum from codeposited metal atoms or substrate atoms; however, it is not yet known if surface porphyrins could metalate from ions in solution, that is, the most likely environment for porphyrin-based devices. Using X-ray photoelectron spectroscopy we have studied the metalation of monolayers and multilayers of a free-base tetraphenyl porphyrin adsorbed on Au(111) with ions in solution. We found that full metalation with Zn can be achieved already at room temperature in contrast with the elevated temperatures required for metalation with codeposited metal atoms.}, author = {Franke, Matthias and Marchini, Florencia and Steinrück, Hans-Peter and Lytken, Ole and Williams, Federico J.}, doi = {10.1021/acs.jpclett.5b02218}, faupublication = {yes}, journal = {Journal of Physical Chemistry Letters}, keywords = {free-base porphyrin; metalation; surface; XPS; ZnTPP}, pages = {4845-4849}, peerreviewed = {Yes}, title = {{Surface} {Porphyrins} {Metalate} with {Zn} {Ions} from {Solution}}, volume = {6}, year = {2015} } @article{faucris.123233044, abstract = {The adsorption and reaction of CO on a monolayer carbide and a bulk carbide, prepared on Mo(110), was studied with synchrotron-based XPS, TPD, and density-functional calculations using slab models. In the experiments on the monolayer carbide, we find two CO species at 140 K, with a saturation coverage of similar to 0.7 ML, while on the bulk carbide, Mo2C, three molecular adsorption states are found, showing a similar total coverage of similar to 0.7 ML at saturation. In addition, CO partly dissociates on both surfaces (monolayer carbide: 7%, bulk carbide: 15%). The calculations on the monolayer carbide show that the adsorption of CO on Mo sites is most stable. At increased coverages, several different adsorption sites on the monolayer carbide become possible. From the core level shifts, an assignment to the experimentally found species becomes available. Upon heating, we find on both carbides the competing processes of desorption, interconversion of different CO species, and dissociation of CO. The detailed quantitative analysis of these processes shows that desorption and dissociation to atomic oxygen and carbon is completed at similar to 400 K on the monolayer carbide and similar to 450 K on the bulk carbide; in both cases, about 35% (0.25 ML) of the initially adsorbed CO decomposes upon heating. Above 800 K, atomic carbon and oxygen desorb associatively, and at 1200 K the carbide surfaces are restore}, author = {Gleichweit, Christoph and Neiß, Christian and Maisel, Sven and Bauer, Udo and Späth, Florian and Höfert, Oliver and Görling, Andreas and Steinrück, Hans-Peter and Papp, Christian}, doi = {10.1021/acs.jpcc.6b11950}, faupublication = {yes}, journal = {Journal of Physical Chemistry C}, pages = {3133-3142}, peerreviewed = {Yes}, title = {{Surface} {Reaction} of {CO} on {Carbide}-{Modified} {Mo}(110)}, volume = {121}, year = {2017} } @article{faucris.257708171, abstract = {We studied the coverage- and temperature-dependent proton transfer and self-metalation reactions of tetraphenylporphyrin molecules containing a carboxyl functional group (MCTPP) on rutile TiO2(110) surfaces. Furthermore, we also determined changes in the molecular geometric and electronic structures as a function of coverage and temperature. The investigation was carried out by means of synchrotron radiation X-ray photoelectron spectroscopy and near-edge X-ray absorption fine structure measurements. We found that at a coverage of 0.2 ML, most MCTPP molecules adsorb with the iminic nitrogen atoms protonated; at 0.5 ML, a decrease in the proportion of protonated molecules is observed; and at a monolayer coverage, most molecules are not protonated. Raising the temperature to above 500 K, where hydroxyl groups recombine to desorb as water, causes a decrease in the number of protonated porphyrin molecules. In roughly the same temperature range, we start to observe the self-metalation of the free-base molecules, which produces flat-lying titanyl porphyrin molecules on the TiO2(110) surface. This reaction is found to be coverage dependent: For 0.2 ML, it starts above 450 K, and for 1.0 ML, temperatures above 650 K are needed. Metalation shifts the surface state located in the semiconductor band gap to lower energies. Our results suggest that protonation and self-metalation depend on the proximity of the macrocycle to the surface and show that metalation modifies the molecular occupied and vacant electronic states.}, author = {Wechsler, Daniel and Vensaus, Priscila and Tsud, Nataliya and Steinrück, Hans-Peter and Lytken, Ole and Williams, Federico J.}, doi = {10.1021/acs.jpcc.1c01133}, faupublication = {yes}, journal = {Journal of Physical Chemistry C}, note = {CRIS-Team WoS Importer:2021-05-07}, pages = {6708-6715}, peerreviewed = {Yes}, title = {{Surface} {Reactions} and {Electronic} {Structure} of {Carboxylic} {Acid} {Porphyrins} {Adsorbed} on {TiO2}(110)}, volume = {125}, year = {2021} } @inproceedings{faucris.237825992, address = {WASHINGTON}, author = {Steinrück, Hans-Peter}, booktitle = {ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY}, date = {2019-08-25/2019-08-29}, faupublication = {yes}, note = {CRIS-Team WoS Importer:2020-04-28}, peerreviewed = {unknown}, publisher = {AMER CHEMICAL SOC}, title = {{Surface} reactions of complex molecular systems: {From} supported graphene to hydrogen storage molecules}, venue = {San Diego, CA}, year = {2019} } @article{faucris.120886304, abstract = {We investigated the surface reaction of the liquid organic hydrogen carrier dicydohexylmethane (DCHM) on Pt(111) in ultrahigh vacuum by high-resolution X-ray photoelectron spectroscopy, temperature-programmed desorption, near-edge X-ray absorption fine structure, and infrared reflection absorption spectroscopy. Additionally, the hydrogen-lean molecule diphenylmethane and the relevant molecular fragments of DCHM, methylcyclohexane, and toluene were studied to elucidate the reaction steps of DCHM. We find dehydrogenation of DCHM in the range of 200-260 K, to form a double-sided pi-allylic species coadsorbed with hydrogen. Subsequently, similar to 30% of the molecules desorb, and for similar to 70%, one of the pi-allyls reacts to a phenyl group between 260 and 330 K, accompanied by associative hydrogen desorption. Above 360 K, the second pi-allylic species is dehydrogenated to a phenyl ring. This is accompanied by C-H bond scission at the methylene group, which is an unwanted decomposition step in the hydrogen storage cycle, as it alters the original hydrogen carrier DCHM. Above 450 K, we find further decomposition steps which we assign to C-H abstraction at the phenyl rings.}, author = {Gleichweit, Christoph and Amende, Maximilian and Höfert, Oliver and Xu, Tao and Späth, Florian and Brückner, Nicole and Wasserscheid, Peter and Libuda, Jörg and Steinrück, Hans-Peter and Papp, Christian}, doi = {10.1021/acs.jpcc.5b06178}, faupublication = {yes}, journal = {Journal of Physical Chemistry C}, pages = {20299-20311}, peerreviewed = {Yes}, title = {{Surface} {Reactions} of {Dicyclohexylmethane} on {Pt}(111)}, volume = {119}, year = {2015} } @article{faucris.309903520, abstract = {The transition to renewable energy sources comes along with the search for new energy storage solutions. Molecular solar thermal systems directly harvest and store solar energy in a chemical manner. By a suitable molecular design, a higher overall efficiency can be achieved. In this study, we investigate the surface chemistry of oxa-norbornadiene/quadricyclane derivatives on a Pt(111) surface. Specifically, we focus on the energy storage and release properties of molecules that are substituted with ester moieties of different sizes. For our model catalytic approach, synchrotron radiation-based x-ray photoelectron spectroscopy measurements were conducted in ultra-high vacuum (UHV) and correlated with the catalytic behavior in the liquid phase monitored by photochemical infrared reflection absorption spectroscopy. The differences in their spectral appearance enabled us to unambiguously differentiate the energy-lean and energy-rich isomers and decomposition products. Next to qualitative information on the adsorption motifs, temperature-programmed experiments allowed for the observation of thermally induced reactions and the deduction of the related reaction pathways. We analyzed the selectivity of the cycloreversion reaction from the energy-rich quadricyclane derivative to its energy-lean norbornadiene isomer and competing processes, such as desorption and decomposition. For the 2,3-bis(methylester)-substitution, the cycloreversion reaction was found to occur between 310 and 340 K, while the thermal stability limit of the compounds was determined to be 380 K. The larger 2,3-bis(benzylester) derivatives have a lower apparent adsorption energy and a decomposition onset already at 135 K. In the liquid phase (in acetonitrile), we determined the rate constants for the cycloreversion reaction on Pt(111) to k = 5.3 × 10-4 s-1 for the 2,3-bis(methylester)-substitution and k = 6.3 × 10-4 s-1 for the 2,3-bis(benzylester) derivative. The selectivities were of >99% and 98% for the two molecules, respectively. The difference in the catalytic behavior of Pt(111) for both derivatives is less pronounced in the liquid phase than in UHV, which we attribute to the passivation of the Pt(111) surface by carbonaceous species under ambient conditions.}, author = {Hemauer, Felix and Krappmann, Daniel and Schwaab, Valentin and Hussain, Zarah and Freiberger, Eva Marie and Waleska-Wellnhofer, Natalie and Franz, Evanie and Hampel, Frank and Brummel, Olaf and Libuda, Jörg and Hirsch, Andreas and Steinrück, Hans-Peter and Papp, Christian}, doi = {10.1063/5.0158124}, faupublication = {yes}, journal = {Journal of Chemical Physics}, note = {CRIS-Team Scopus Importer:2023-09-01}, peerreviewed = {Yes}, title = {{Surface} science and liquid phase investigations of oxanorbornadiene/oxaquadricyclane ester derivatives as molecular solar thermal energy storage systems on {Pt}(111)}, volume = {159}, year = {2023} } @article{faucris.107840524, abstract = {Materials making use of thin ionic liquid (IL) films as support-modifying functional layer open up a variety of new possibilities in heterogeneous catalysis, which range from the tailoring of gas-surface interactions to the immobilization of molecularly defined reactive sites. The present report reviews recent progress towards an understanding of &quot;supported ionic liquid phase (SILP)&quot; and &quot;solid catalysts with ionic liquid layer (SCILL)&quot; materials at the microscopic level, using a surface science and model catalysis type of approach. Thin film IL systems can be prepared not only ex-situ, but also in-situ under ultrahigh vacuum (UHV) conditions using atomically well-defined surfaces as substrates, for example by physical vapor deposition (PVD). Due to their low vapor pressure, these systems can be studied in UHV using the full spectrum of surface science techniques. We discuss general strategies and considerations of this approach and exemplify the information available from complementary methods, specifically photoelectron spectroscopy and surface vibrational spectroscopy. Copyright &copy; 2011 WILEY-VCH Verlag GmbH &amp; Co. KGaA, Weinheim.}, author = {Steinrück, Hans-Peter and Libuda, Jörg and Wasserscheid, Peter and Cremer, Till and Kolbeck, Claudia and Laurin, Mathias and Maier, Florian and Sobota, Marek and Schulz, Peter and Stark, Michael Werner}, doi = {10.1002/adma.201100211}, faupublication = {yes}, journal = {Advanced Materials}, pages = {2571-2587}, peerreviewed = {Yes}, title = {{Surface} science and model catalysis with ionic liquid-modified materials}, volume = {23}, year = {2011} } @article{faucris.108275464, abstract = {Ionic liquids are a new class of materials with most interesting properties. They are liquid at room temperature, but have a negligible vapour pressure. Consequently they can, in contrast to normal liquids, be investigated by all UHV-based methods of surface science. This allows to determine their properties with the same atomic level accuracy that is presently common for solid surfaces and conventional adsorbate systems. Apart from the investigation of the specific properties of ionic liquids, which are relevant for many applications, this also opens the possibility to obtain more detailed insight in the general physical and chemical properties of liquids. In that sense it opens the door to a new chapter of surface science - &quot;Ionic Liquid Surface Science&quot;. &copy; 2010 Elsevier B.V. All rights reserved.}, author = {Steinrück, Hans-Peter}, doi = {10.1016/j.susc.2009.12.033}, faupublication = {yes}, journal = {Surface Science}, pages = {481-484}, peerreviewed = {Yes}, title = {{Surface} science goes liquid !}, volume = {604}, year = {2010} } @article{faucris.108390964, abstract = {The exclusive use of the specularly reflected beam (the (0,0) spot) may be a more practical way of collecting data for a LEED I-V structure analysis under certain experimental conditions. In this paper we discuss the special properties of the (0,0) spot intensity and test its sensitivity towards structural changes for the model system CO/Ni(1 1 1) within the framework of a R factor analysis. It is found that the (0,0) spot can, indeed, be used for a reliable structure determination if the energy range is increased by collecting data at different polar and azimuthal angles of incidence. The R factor contrast is, however, reduced with respect to a conventional LEED I-V analysis. &copy; 2001 Elsevier Science B.V. All rights reserved.}, author = {Held, Georg and Steinrück, Hans-Peter}, doi = {10.1016/S0039-6028(01)01327-9}, faupublication = {yes}, journal = {Surface Science}, pages = {274-284}, peerreviewed = {Yes}, title = {{Surface} structure analysis based on the exclusive use of the specular {LEED} spot - {A} theoretical study}, volume = {490}, year = {2001} } @article{faucris.113336784, abstract = {The applicability of photoelectron holography to determine the structure of clean and adsorbate-covered metal surfaces is investigated. The real space structure of various systems is reconstructed from photoelectron diffraction patterns at various kinetic energies using (1) the single wavenumber and (2) the multiple wavenumber reconstruction algorithm. It is demonstrated that adsorption sites can be unequivocally identified using the multiple wavenumber approach.}, author = {Zharnikov, M. and Weinelt, Martin and Zebisch, P. and Steinrück, Hans-Peter}, doi = {10.1016/0040-6090(95)07059-1}, faupublication = {no}, journal = {Thin Solid Films}, pages = {266-269}, peerreviewed = {Yes}, title = {{Surface} structure characterization by photoelectron holography}, volume = {275}, year = {1996} } @article{faucris.294851484, abstract = {Novel energy-storage solutions are necessary for the transition from fossil to renewable energy sources. Auspicious candidates are so-called molecular solar thermal (MOST) systems. In our study, we investigate the surface chemistry of a derivatized norbornadiene/quadricyclane molecule pair. By using suitable push–pull substituents, a bathochromic shift of the absorption onset is achieved, allowing a greater overlap with the solar spectrum. Specifically, the adsorption and thermally induced reactions of 2-carbethoxy-3-phenyl-norbornadiene/quadricyclane are assessed on Pt(111) and Ni(111) as model catalyst surfaces by synchrotron radiation-based X-ray photoelectron spectroscopy (XPS). Comparison of the respective XP spectra enables the distinction of the energy-rich molecule from its energy-lean counterpart and allows qualitative information on the adsorption motifs to be derived. Monitoring the quantitative cycloreversion between 140 and 230 K spectroscopically demonstrates the release of the stored energy to be successfully triggered on Pt(111). Heating to above 300 K leads to fragmentation of the molecular framework. On Ni(111), no conversion of the energy-rich compound takes place. The individual decomposition pathways of the two isomers begin at 160 and 180 K, respectively. Pronounced desorption of almost the entire surface coverage only occurs for the energy-lean molecule on Ni(111) above 280 K; this suggests weakly bound species. The correlation between adsorption motif and desorption behavior is important for applications of MOST systems in heterogeneously catalyzed processes.}, author = {Hemauer, Felix and Schwaab, Valentin and Freiberger, Eva Marie and Waleska, Natalie and Leng, Andreas and Weiß, Cornelius and Steinhauer, Johann and Düll, Fabian and Bachmann, Philipp and Hirsch, Andreas and Steinrück, Hans-Peter and Papp, Christian}, doi = {10.1002/chem.202203759}, faupublication = {yes}, journal = {Chemistry - A European Journal}, keywords = {catalysis; energy storage; MOST system; photoelectron spectroscopy; surface reactions}, note = {CRIS-Team Scopus Importer:2023-03-31}, peerreviewed = {Yes}, title = {{Surface} {Studies} on the {Energy} {Release} of the {MOST} {System} 2-{Carbethoxy}-3-{Phenyl}-{Norbornadiene}/{Quadricyclane} ({PENBD}/{PEQC}) on {Pt}(111) and {Ni}(111)}, year = {2023} } @article{faucris.308917853, abstract = {In the present study, we investigated the surface tension and viscosity of binary ionic liquid (IL) mixtures at or close to saturation conditions from high vacuum conditions up to elevated pressures. We studied four different mixtures of 1,3-bis(2-(2-methoxyethoxy)ethyl)imida-zolium iodide ([(mPEG2)2Im]I) and 1-methyl-3-octylimidazolium hexafluorophosphate ([C8C1Im][PF6]) with [C8C1Im][PF6] mole contents between (4.6 and 49.8) mol%. Argon (Ar) gas of relatively low solubility was used to vary the applied pressure between (0.1 and 10) MPa. For temperatures from (303 to 363) K, the surface tension obtained by the pendant-drop (PD) method was used to determine the saturated liquid viscosity from surface light scattering (SLS). These studies are complemented by additional PD measurements under ultraclean high vacuum (HV) conditions in a second setup. At about 0.1 MPa, the surface tension and viscosity of the IL mixtures show negative deviations from a linear mixing rule based on the molar bulk composition, which is more pronounced at lower temperatures. The surface tension values at 0.1 MPa and under HV agree with each other and lie closer to the values of [C8C1Im][PF6] that has a distinctly lower surface tension than [(mPEG2)2Im]I and is surface-active. For the equimolar IL mixture at 303 K, an increase in the pressure up to 10 MPa has a negligible influence on the viscosity, while it causes a distinct reduction in the surface tension compared to the value at 0.1 MPa. The pressure-dependent relative change for the viscosity of the ternary mixtures of the two ILs and Ar corresponds well to the mean values of the positive and negative relative changes observed for the two binary [(mPEG2)2Im]I-Ar and [C8C1Im][PF6]-Ar subsystems, respectively. For the surface tension, the absolute changes at a given pressure are very similar regardless of the IL bulk composition, suggesting a similar weak Ar enrichment at the gas–liquid interface.}, author = {Zhai, Ziwen and Paap, Ulrike and Gezmis, Afra and Maier, Florian and Steinrück, Hans-Peter and Koller, Thomas Manfred}, doi = {10.1016/j.molliq.2023.122388}, faupublication = {yes}, journal = {Journal of Molecular Liquids}, keywords = {Ionic liquid mixtures; Pendant-drop method; Pressure; Surface light scattering; Surface tension; Viscosity}, note = {CRIS-Team Scopus Importer:2023-08-11}, peerreviewed = {Yes}, title = {{Surface} tension and viscosity of binary ionic liquid mixtures from high vacuum up to pressures of 10 {MPa}}, volume = {386}, year = {2023} } @article{faucris.241742529, abstract = {Mixtures of fluorinated and non-fluorinated ionic liquids (ILs) show a distinct structural organization in the bulk and at the surface. To understand how such microscopic effects influence the macroscopic bulk and surface properties of IL mixtures, knowledge of corresponding thermophysical properties including viscosity and surface tension is required yet lacking. With the intention of investigating surface enrichment effects of the fluorinated IL [PFBMIm][PF6] (3-methyl-1-(3,3,4,4,4-pentafluorobutyl)imidazolium hexafluorophosphate) in mixtures with the structurally similar, non-fluorinated IL [C4C1Im][PF6] (1-butyl-3-methylimidazolium hexafluorophosphate) observed with angle-resolved X-ray photoelectron spectroscopy (ARXPS), the pendant drop method and surface light scattering (SLS) were applied in the present study to determine surface tension and dynamic viscosity between (293 and 368) K. By adding small amounts of [PFBMIm][PF6] up to 9 mol %, a distinct increase in the viscosity and decrease in the surface tension of the mixtures relative to the properties of pure [C4C1Im][PF6] was found. This behavior reflects the nanosegregated structure in the bulk and at the surface of the binary IL mixtures. Using the results about the pronounced surface enrichment of the fluorinated chain of [PFBMIm][PF6] quantified by ARXPS, a linear mixing rule for the surface tension of the IL mixtures based on the surface tensions of the pure ILs and the surface concentration of their most surface-active groups is suggested.}, author = {Koller, Thomas Manfred and Lenahan, Frances and Schmidt, Patrick and Klein, Tobias and Mehler, Julian and Maier, Florian and Rausch, Michael Heinrich and Wasserscheid, Peter and Steinrück, Hans-Peter and Fröba, Andreas Paul}, doi = {10.1007/s10765-020-02720-w}, faupublication = {yes}, journal = {International Journal of Thermophysics}, keywords = {Ionic liquids; Mixtures; Pendant drop method; Surface light scattering; Surface tension; Viscosity}, note = {CRIS-Team Scopus Importer:2020-08-21}, peerreviewed = {Yes}, title = {{Surface} {Tension} and {Viscosity} of {Binary} {Mixtures} of the {Fluorinated} and {Non}-fluorinated {Ionic} {Liquids} [{PFBMIm}][{PF6}] and [{C4C1Im}][{PF6}] by the {Pendant} {Drop} {Method} and {Surface} {Light} {Scattering}}, volume = {41}, year = {2020} } @article{faucris.123787884, abstract = {Combining in vacuo deposition of ultrathin ionic liquid (UTIL) films with angle-resolved X-ray photoelectron spectroscopy (ARXPS), we demonstrate that by deposition of submonolayer amounts of Pd onto Au(111) the initial growth mode of the ionic liquid (IL) 1-ethyl-3-methylimidazolium trifluoro-methanesulfonate ([C(2)C(1)lm][OTf]) can be switched from three-dimensional (3D) to two-dimensional (2D) growth, that is, from non-wetting to wetting. On clean Au(111), pronounced 3D growth occurs on top of an initially formed 2D wetting layer with cations and anions next to each other in a checkerboard arrangement. After pre- or postdeposition of only 0.7 ML Pd, two-dimensional layer-by-layer growth is found, which is attributed to strong attractive interactions between [C(2)C(1)lm][OTf] and surface Pd. For Pd post deposition onto the IL, the ARXPS data revealed particularly strong interactions between the dialkylimidazolium cation and Pd atoms, which considerably reduce the regular surface alloying of Pd with the Au substrate stabilizing Pd at the metal surface. In the context of heterogeneous catalysis using the SCILL (solid catalyst coated with ionic liquid layer) concept, these results directly provide a possible explanation on the molecular level for the beneficial influence of the IL layer in case of heterogeneous metal alloy catalysts.}, author = {Rietzler, Florian and May, Benjamin and Steinrück, Hans-Peter and Maier, Florian}, doi = {10.1039/c6cp04938a}, faupublication = {yes}, journal = {Physical Chemistry Chemical Physics}, pages = {25143-25150}, peerreviewed = {Yes}, title = {{Switching} adsorption and growth behavior of ultrathin [{C}(2){C}(1)lm][{OTf}] films on {Au}(111) by {Pd} deposition}, volume = {18}, year = {2016} } @article{faucris.309911783, abstract = {The solid catalyst with ionic liquid layer (SCILL) concept is a promising approach to enhance the selectivity of hydrogenation reactions, like the selective hydrogenation of 1,3-butadiene to 1-butene using transition-metal catalysts. In this context, the adsorption dynamics of 1,3-butadiene and 1-butene were studied on Pt(111) modified with ultrathin layers of the ionic liquid (IL) 1,3-dimethylimidazolium bis(trifluoromethanesulfonyl)imide ([C1C1Im][Tf2N]). The sticking coefficients of the two hydrocarbons are measured using the direct method of King and Wells. Both olefins show pronounced precursor-mediated dynamics on clean Pt(111) and on the IL-modified surface. Increasing the IL coverage leads to an increased blocking of adsorption sites for the incoming olefins. Coadsorbed hydrogen does not significantly affect the precursor and site-blocking effects for 1,3-butadiene. Interestingly, a smaller IL amount is needed to prevent 1-butene adsorption compared to 1,3-butadiene adsorption, which is proposed to be directly related to the IL’s influence on selective hydrogenation in SCILL catalysis. Indeed, molecular dynamics simulations show IL film densification/relaxation as the key mechanism to allowing/excluding olefin adsorption on the metal. Being a function of IL coverage, the energy of film penetration is used to control the effective olefin adsorption energy and thus creates an operation regime for suppressing 1-butene while permitting 1,3-butadiene adsorption.}, author = {Winter, Leonhard and Trzeciak, Simon and Fernandez, Cynthia and Massicot, Stephen and Talwar, Timo and Maier, Florian and Zahn, Dirk and Steinrück, Hans-Peter}, doi = {10.1021/acscatal.3c02126}, faupublication = {yes}, journal = {ACS Catalysis}, keywords = {adsorption; gas-surface dynamics; hydrogenation; ionic liquids; molecular beam; molecular dynamics; SCILL; selectivity}, note = {CRIS-Team Scopus Importer:2023-09-01}, pages = {10866-10877}, peerreviewed = {Yes}, title = {{Tailoring} the {Selectivity} of 1,3-{Butadiene} versus 1-{Butene} {Adsorption} on {Pt}(111) by {Ultrathin} {Ionic} {Liquid} {Films}}, year = {2023} } @article{faucris.321946389, abstract = {The so-called buoy-effect, that is, the targeted surface enrichment of a Pt catalyst dissolved in ionic liquids (ILs), is achieved by attaching perfluorinated alkyl chains to the ligand system, which drags the metal complex toward the interface. Using angle-resolved X-ray photoelectron spectroscopy, it is demonstrated how this surface enrichment can be tailored by variation of the solvent IL. In [CnC1Im][PF6] ILs (n = 2, 4, 8), the surface is fully saturated with the complex at 10%mol bulk content, while in [C4C1Im][Tf2N] only at 20%mol saturation is observed. At low catalyst concentrations of 1%mol, where saturation is not yet reached, the enrichment increases with decreasing length of the IL alkyl chain. As a general rule, the degree of surface enrichment decreases with the decrease in surface tension of the solvent IL, that is, in the order [C2C1Im][PF6] > [C4C1Im][PF6] > [C8C1Im][PF6] > [C4C1Im][Tf2N]. In ILs with very low surface tension, enrichment is even suppressed. These results reveal the surface tension of the solvent IL as rational parameter for tailoring the interfacial structure of IL-based catalyst systems, such as supported ionic liquid phase (SILP) catalysis, where the nature of the IL/gas interface is expected to strongly influence the performance of the process.}, author = {Hemmeter, Daniel and Gezmis, Afra and Kremitzl, Daniel and Wasserscheid, Peter and Maier, Florian and Steinrück, Hans-Peter}, doi = {10.1002/admi.202301085}, faupublication = {yes}, journal = {Advanced Materials Interfaces}, keywords = {materials properties; Pt catalyst; supported ionic liquid phase catalysis (SILP); surface enrichment; X-ray photoelectron spectrsocopy}, note = {CRIS-Team Scopus Importer:2024-05-03}, peerreviewed = {Yes}, title = {{Tailoring} the {Surface} {Enrichment} of a {Pt} {Catalyst} in {Ionic} {Liquid} {Solutions} by {Choice} of the {Solvent}}, year = {2024} } @article{faucris.121713284, author = {Sykes, E. Charles H. and Steinrück, Hans-Peter}, doi = {10.1021/acs.accounts.5b00432}, faupublication = {yes}, journal = {Accounts of Chemical Research}, peerreviewed = {unknown}, title = {{Taking} a {Nanoscale} "look" at {Chemical} {Reactions} on {Surfaces}}, volume = {48}, year = {2015} } @inproceedings{faucris.108693684, author = {Luger, M. and Winkler, A. and Rendulic, K.D. and Steinrück, Hans-Peter}, booktitle = {Symposium on Surface Science 3S'85}, editor = {G. Betz, H. Störi, W. Husinsky, P. Varga}, faupublication = {no}, pages = {107-112}, publisher = {Proceeding Symposium on Surface Science}, series = {Proceeding Symposium on Surface Science 3S'85 (Obertraun)}, title = {{Temperature} dependance of the sticking coefficient for {H} ₂ on various nickel surfaces}, venue = {Obertraun}, year = {1985} } @inproceedings{faucris.122385384, author = {Luger, M. and Winkler, A. and Rendulic, K.D. and Steinrück, Hans-Peter}, booktitle = {Proc. Symposium on Surface Science}, faupublication = {no}, note = {UnivIS-Import:2015-04-16:Pub.1985.nat.dchph.lpc2.temper}, pages = {107-112}, title = {{Temperature} dependence of the sticking coefficient for {H2} on various nickel surfaces}, venue = {Obertraun}, year = {1985} } @article{faucris.120318264, abstract = {Temperature-dependent chemical and structural changes of a submonolayer of 2H-tetraphenylporphyrin (2HTPP) on Cu(111) were studied with photoelectron spectroscopy (XPS/UPS) and scanning tunneling microscopy (STM). 2HTPP reacts with Cu atoms from the substrate to form copper(II)-tetraphenylporphyrin (CuTPP). This metalation reaction starts at about 400 K and was investigated at various temperatures up to 500 K. At room temperature, adsorbed 2HTPP adopts an orientation with the molecular plane parallel to the substrate; the same holds for its reaction product CuTPP after annealing to 400 K. In contrast, annealing at 450 K yields a tilted orientation of CuTPP, as indicated by STM and supported by C 1s XPS shifts and changes in the Cu(111) surface state. Subsequent annealing at 500 K restores a flat-lying orientation; however, the appearance of the complex in STM images differs from the original appearance of CuTPP. In summary, 2HTPP undergoes three irreversible transformations upon annealing on Cu(111), a metalation reaction to CuTPP followed by two intramolecular structural changes. &copy; 2012 American Chemical Society.}, author = {Xiao, Jie and Ditze, Stefanie and Chen, Min and Buchner, Florian and Stark, Michael Werner and Drost, Martin and Steinrück, Hans-Peter and Gottfried, J. Michael and Marbach, Hubertus}, doi = {10.1021/jp301757h}, faupublication = {yes}, journal = {Journal of Physical Chemistry C}, pages = {12275-12282}, peerreviewed = {Yes}, title = {{Temperature}-dependent chemical and structural transformations from {2H}-tetraphenylporphyrin to copper({II})-tetraphenylporphyrin on {Cu}(111)}, volume = {116}, year = {2012} } @article{faucris.108393384, abstract = {The initial stages of surface oxidation were investigated for pseudomorphic Ni layers (1-3 ML) on Cu(1 1 1) after oxygen adsorption at 150 and 300 K. At 150 K, the oxidation proceeds in a two-step process: first, oxygen chemisorbs on the surface up to a coverage of 0.7 ML leaving the top-most Ni atoms metallic. In the second step these Ni atoms are oxidized parallel to the adsorption of additional sub-surface oxygen (up to 2.0 ML), which is indicated by drastic changes in the Ni2p spectra. No bulk oxidation beyond the first layer of metal atoms is observed after adsorption at 150 K. At 300 K, the mobility of the Ni atoms is high enough to allow also the oxidation of the lower lying metal atoms and the formation of NiO clusters on the surface. The sequence of chemisorption and oxidation and the amount of oxygen required for the complete oxidation of 1 ML Ni is the same as for 150 K. &copy; 2002 Elsevier Science B.V. All rights reserved.}, author = {Domnick, Ralph and Held, Georg and Steinrück, Hans-Peter}, doi = {10.1016/S0039-6028(02)01854-X}, faupublication = {yes}, journal = {Surface Science}, pages = {95-102}, peerreviewed = {Yes}, title = {{Temperature} dependent oxidation of thin {Ni} layers on {Cu}(1 1 1)}, volume = {516}, year = {2002} } @article{faucris.120523524, abstract = {We have investigated the adsorption and temperature-dependent reactions of phthalic acid on Ag(100), in the temperature range 110-700 K, by synchrotron radiation X-ray photoelectron spectrocopy (SR-XPS), temperature-programmed desorption (TPD) and near-edge X-ray absorption fine structure (NEXAFS). Phthalic acid adsorbs intact at 110 K, but decomposes to phthalic anhydride and polyanhdride at 150 K. When heated further, phthalic anhydride desorbs at 250 K, leaving only polyanhydride on the surface, which at 350 K decomposes into a carboxylate, through desorption of phthalic anhydride and water. The carboxylate is stable until 500 K, after which it decomposes, through desorption of CO and benzene, into carbon; the latter diffuses into the bulk, leaving only a little carbon on the Ag(100) surface at 600 K.}, author = {Franke, Matthias and Marchini, Florencia and Zhang, Liang and Tariq, Quratulain and Tsud, Nataliya and Vorokhta, Mykhailo and Vondráček, Martin and Prince, Kevin C. and Röckert, Michael and Williams, Federico J. and Steinrück, Hans-Peter and Lytken, Ole}, doi = {10.1021/acs.jpcc.5b07858}, faupublication = {yes}, journal = {Journal of Physical Chemistry C}, pages = {23580-23585}, peerreviewed = {unknown}, title = {{Temperature}-{Dependent} {Reactions} of {Phthalic} {Acid} on {Ag}(100)}, volume = {119}, year = {2015} } @article{faucris.233235257, abstract = {Using angle-resolved X-ray photoelectron spectroscopy (ARXPS), we investigate the topmost nanometers of various binary ionic liquid (IL) mixtures at different temperatures in the liquid state. The mixtures consist of ILs with the same [PF<inf>6</inf>]⁻ anion but two different cations, namely 3-methyl-1-(3,3,4,4,4-pentafluorobutyl)imidazolium hexafluorophosphate, [PFBMIm][PF<inf>6</inf>], and 1-butyl-3-methylimidazolium hexafluorophosphate, [C<inf>4</inf>C<inf>1</inf>Im][PF<inf>6</inf>], with 10, 25, 50 and 75 mol % content of [PFBMIm][PF<inf>6</inf>]. We observe a preferential enrichment of the fluorinated chain in the topmost layer, relative to the bulk composition, which is most pronounced for the lowest content of [PFBMIm][PF<inf>6</inf>]. Upon cooling the mixtures stepwise from 95 °C until surface charging effects in XPS indicate solidification, we observe a pronounced increase in surface enrichment of the fluorinated chain with decreasing temperature in the liquid state. In contrast to the mixtures with lower [PFBMIm][PF<inf>6</inf>] contents, cooling the 75 mol % mixture additionally shows an abrupt decrease of the fluorinated chain signal before complete solidification occurs, which is assigned to partial precipitation effects.}, author = {Heller, Bettina and Lexow, Matthias and Greco, Francesco and Shin, Sunghwan and Partl, Gabriel and Maier, Florian and Steinrück, Hans-Peter}, doi = {10.1002/chem.201904438}, faupublication = {yes}, journal = {Chemistry - A European Journal}, keywords = {ionic liquids; mixtures; photoelectron spectroscopy; surface enrichment}, month = {Jan}, note = {CRIS-Team Scopus Importer:2020-02-04}, pages = {1117-1126}, peerreviewed = {Yes}, title = {{Temperature}-{Dependent} {Surface} {Enrichment} {Effects} in {Binary} {Mixtures} of {Fluorinated} and {Non}-{Fluorinated} {Ionic} {Liquids}}, volume = {26}, year = {2020} } @article{faucris.107804664, abstract = {We present the first systematic study of the influence of temperature on the degree of surface enrichment of 1-alkyl-3-methylimidazolium-based ionic liquids (ILs). Using angle-resolved X-ray photoelectron spectroscopy, we demonstrate that the degree of surface enrichment strongly decreases with increasing temperature for all the studied ILs. For ILs with the same cation, but different anions, [CCIm]Br, [CC Im][TfO] and [CCIm][TfN], no significant differences of the temperature-induced partial loss of surface enrichment are found. Measurements for [CCIm][TfO], [CCIm][TfO] and [CCIm][TfO] indicate a small effect of the chain length. For [CC Im][TfO], a continuous decrease of alkyl surface enrichment is found with increasing temperature, with no abrupt changes at the phase-transition temperature from the smectic A to the isotropic phase, indicating that the surface enrichment is not affected by this phase transition. Loss of order! The surface enrichment of the alkyl chains of five imidazolium-based ionic liquids (ILs) at the liquid/vacuum interface is studied as a function of temperature by angle-resolved X-ray photoelectron spectroscopy; both the anion and the alkyl chain length at the cation are varied. At room temperature, the alkyl chains are enriched at the outer surface. Upon increasing the temperature, the degree of surface enrichment decreases. Copyright &copy; 2013 WILEY-VCH Verlag GmbH &amp; Co. KGaA, Weinheim.}, author = {Kolbeck, Claudia and Deyko, Alexey and Matsuda, Takashi and Kohler, Florian and Wasserscheid, Peter and Maier, Florian and Steinrück, Hans-Peter}, doi = {10.1002/cphc.201300719}, faupublication = {yes}, journal = {ChemPhysChem}, pages = {3726-3730}, peerreviewed = {Yes}, title = {{Temperature}-dependent surface-enrichment effects of imidazolium-based ionic liquids}, volume = {14}, year = {2013} } @article{faucris.272767319, abstract = {Gallium indium alloys are known to be liquid at remarkably low temperatures. Herein, we provide X-ray photoelectron spectroscopy (XPS) studies and DFT-based ab-initio molecular dynamics (MD) calculations on the composition of the liquid alloy surface. We find that alloying Ga and In in ratios close to the eutectic composition results in only minor signal shifts of the corresponding In core levels. The topmost surface layer of the liquid alloy exhibits significant In enrichment for all measured temperatures, between 300 K to 800 K the observed enrichment slightly decreases with increasing temperature. This behavior is seen in both temperature-dependent XPS and ab-initio MD simulations. Furthermore, we investigate changes in the surface composition during the liquid-to-solid phase transition by time-dependent XPS during cooling of the alloy sample. The surface of the alloy presents an advantageous nucleation site, where we regularly observe the precipitation of indium. During cooling, the precipitation processes were followed by both XPS and by monitoring the sample temperature/heating power.}, author = {Wittkämper, Haiko and Maisel, Sven and Moritz, Michael and Grabau, Mathias and Görling, Andreas and Steinrück, Hans-Peter and Papp, Christian}, doi = {10.1016/j.susc.2021.122008}, faupublication = {yes}, journal = {Surface Science}, keywords = {DFT; GaIn; XPS}, note = {CRIS-Team Scopus Importer:2022-04-14}, peerreviewed = {Yes}, title = {{Temperature}-dependent {XPS} studies on {Ga}-{In} alloys through the melting-point}, volume = {717}, year = {2022} } @article{faucris.108394264, abstract = {We demonstrate that adsorbed meso-tetraphenylporphyrin molecules can coordinate Zn atoms that are pre-deposited on an Ag(111) surface, forming a complex that is identical to directly deposited tetraphenylporphyrinato-zinc(ii) ; this reaction, which we studied with XPS, is the first example of an oxidative dissolution of a metal by a large organic ligand under ultrahigh vacuum conditions. &copy; The Royal Society of Chemistry.}, author = {Kretschmann, Andreas and Walz, Marie-Madeleine and Flechtner, Ken and Steinrück, Hans-Peter and Gottfried, Michael}, doi = {10.1039/b614427f}, faupublication = {yes}, journal = {Chemical Communications}, note = {UnivIS-Import:2015-04-14:Pub.2007.nat.dchph.lpc2.tetrap}, pages = {568-570}, peerreviewed = {Yes}, title = {{Tetraphenylporphyrin} picks up zinc atoms from a silver surface}, year = {2007} } @article{faucris.108484684, abstract = {The adsorption of acetylene on Ni(110) was investigated by temperature programmed desorption (TPD), low energy electron diffraction (LEED), angle resolved ultraviolet-photoelectron spectroscopy (ARUPS), and near edge x-ray absorption fine structure (NEXAFS) measurements, as well as by detailed model cluster calculations and slab model band structure calculations. By combining the experimental results and those of the cluster studies an orientation of the molecules is deduced with the C-C axis parallel to the surface and preferentially aligned along the substrate troughs ([110] azimuth) as well as with a highly coordinated adsorption site in the substrate troughs. A detailed analysis of the photoemission spectrum is given. The proposed adsorption geometry is corroborated by band structure calculations for various alternative sites and orientations that are shown to be very sensitive to the azimuthal orientation of the adsorbed molecules. &copy; 1995 American Institute of Physics.}, author = {Weinelt, M. and Huber, W. and Zebisch, P. and Steinrück, Hans-Peter and Ulbricht, P. and Birkenheuer, U. and Boettger, J.C. and Rösch, Notker}, doi = {10.1063/1.468790}, faupublication = {no}, journal = {Journal of Chemical Physics}, pages = {9709-9724}, peerreviewed = {Yes}, title = {{The} adsorption of acetylene on {Ni}(110): {An} experimental and theoretical study}, volume = {102}, year = {1995} } @article{faucris.121451924, abstract = {Benzene adsorption on Ni(111) has been studied by LEED and TPD for adsorption temperatures between 110 and 310 K. At initial coverages &theta; &lt; 0.05 ML (relative to Ni) complete decomposition of benzene occurs upon heating above 650 K. At higher coverages (&theta; &gt; 0.05 ML) molecular desorption precedes decomposition. The saturation coverage of chemisorbed benzene can only be achieved at adsorption temperatures below 270 K and reveals a sharp (&radic;7&times;&radic;7)R19.1&deg; LEED pattern corresponding to a coverage of 0.143 ML. This LEED pattern disappears upon heating to 300 K; simultaneously a very sharp molecular benzene desorption peak is observed at 294 K, indicating that desorption is coupled to this order-disorder phase transition. A previously reported (2&radic;3&times; 2&radic;3)R30 &deg; structure for room temperature adsorption can only be observed by coadsorbing CO; the relative coverages in the coadsorbed benzene + CO layer are &theta; : theta; = 1:2. Adsorption of benzene at 110 K leads to the formation of multilayers. Three distinct states, &alpha; , &alpha; and &alpha; can be resolved with desorption temperatures of 154, 136 and 146 K, respectively. The &alpha; peak corresponds to the first physisorbed layer on top of the chemisorbed benzene, probably also oriented parallel to the surface. The &alpha; peak exhibits typical zero-order desorption behaviour and is attributed to bulk sublimation. The &alpha; peak seems to be due to a transition layer between the &alpha; layer and bulk benzene. This behaviour is similar to that observed before on Ru(001). For chemisorbed and physisorbed benzene we compile and compare the results on other surfaces. &copy; 1989.}, author = {Steinrück, Hans-Peter and Huber, W. and Pache, T. and Menzel, Dietrich}, faupublication = {no}, journal = {Surface Science}, pages = {293-316}, peerreviewed = {Yes}, title = {{The} adsorption of benzene mono- and multilayers on {Ni}(111) studied by {TPD} and {LEED}}, url = {https://www.scopus.com/record/display.uri?eid=2-s2.0-26744469078&origin=inward}, volume = {218}, year = {1989} } @article{faucris.108466204, abstract = {Using TPD, ARUPS, XPS, LEED and work function measurements the adsorption of water has been studied on the clean Ni(111) surface and on a Ni(111) surface precovered with 0.25 ML of oxygen. For the clean surface the saturation coverage of chemisorbed water is determined to 0.66 ML by XPS. The observed ( 3 &times; 3)R30&deg; structure must then be non-primitive containing two molecules per unit cell. Angle resolved UPS spectra show a splitting of the 3a level indicating the existence of two nonequivalent molecules in the chemisorbed layer, both being tilted with respect to the surface normal. The so-called &quot;bilayer&quot; structure is proposed for this saturated chemisorbed layer. The TPD spectra show three distinct peaks at 171, 152 and 158 K that are attributed to desorption from the chemisorbed bilayer, a transition layer and condensed water, respectively. Upon oxygen preadsorption an additional peak is observed in TPD of water reaching from 180 to 260 K with a saturation coverage of 0.25 ML. This peak is attributed to intact HO molecules directly chemisorbed on the Ni(111) surface. The angle resolved UPS spectra show very distinct angular dependences of all molecular levels. No evidence for dissociation is found. The orientation of the molecules is proposed to be tilted perpendicular to the molecular plane possibly due to hydrogen bonding to two neighbouring oxygen atoms. &copy; 1989.}, author = {Pache, T. and Steinrück, Hans-Peter and Huber, W. and Menzel, Dietrich}, doi = {10.1016/0039-6028(89)90910-2}, faupublication = {no}, journal = {Surface Science}, pages = {195-214}, peerreviewed = {Yes}, title = {{The} adsorption of {H2O} on clean and oxygen precovered {Ni}(111) studied by {ARUPS} and {TPD}}, volume = {224}, year = {1989} } @article{faucris.120434204, abstract = {The adsorption of HO on a Ni(111) surface precovered with various amounts of potassium has been studied by TPD, work-function measurements, and angle-resolved UPS using linearly polarized synchrotron radiation. Coadsorption of potassium leads to major changes in the desorption characterics of water which depend strongly on the amount of preadsorbed potassium. At potassium precoverages below &theta; &asymp; 0.14 ML water is molecularly adsorbed; for higher potassium precoverages dissociation of HO into an OH species as well as molecular adsorption is observed at 110 K. The molecularly bound species is significantly stabilized on the surface, as concluded from a high temperature desorption state (170-280 K) in TPD. At low potassium precoverages approximately three HO molecules are affected by one potassium atom. Using symmetry selection rules the symmetry of the adsorbed HO molecules is determined to C(&sigma;), which is probably due to a tilting in the HOH plane. At high potassium precoverages HO decomposes upon adsorption forming an OH species; this OH species is stable up to temperatures above 400 K. The ratio of K to OH formed by dissociation is found to be about 1. From the angle and polarization dependences of the molecular orbitals a tilted orientation of the OH species is derived. The results are compared to those obtained for HO adsorption on clean and oxygen-precovered Ni(111) surfaces, and other alkali/metal systems. &copy; 1991.}, author = {Bornemann, T. and Steinrück, Hans-Peter and Huber, W. and Eberle, K. and Glanz, M. and Menzel, Dietrich}, doi = {10.1016/0039-6028(91)90643-7}, faupublication = {no}, journal = {Surface Science}, pages = {105-118}, peerreviewed = {Yes}, title = {{The} adsorption of {H2O} on {K} precovered {Ni}(111) studied by {ARUPS} and {TPD}}, volume = {254}, year = {1991} } @article{faucris.108396904, abstract = {Adsorption of NO on a Pt(111) surface pre-covered with a p(2&times;2) atomic oxygen layer has been studied in situ by high-resolution X-ray photoelectron spectroscopy and temperature-programmed XPS using third-generation synchrotron radiation at BESSY II, Berlin, combined with molecular beam techniques and ex situ by low energy electron diffraction and temperature-programmed desorption. O 1s XP spectra reveal that an ordered p(2&times;2)-O layer dramatically changes the adsorption behavior of NO as compared to the clean surface. The atomic oxygen occupies fcc hollow sites, and therefore blocks NO adsorption on these sites, which are energetically preferred on clean Pt(111). As a consequence, NO populates on-top sites at low coverage. At 110 K for higher coverages, NO can additionally adsorb on hcp hollow sites, thereby inducing a shift of the O 1s binding energy of atomic oxygen towards lower energies by about 0.25 eV. The bond strength of the hcp hollow NO species to the substrate is weakened by the presence of atomic oxygen. A sharp p(2&times;2) LEED pattern is observed for NO adsorption on the oxygen pre-covered surface, up to saturation coverage. The total saturation coverage of NO on Pt(111) pre-covered with varying amounts of oxygen (below 0.25 ML) decreases linearly with the coverage of oxygen. The initial sticking coefficient of NO is reduced from 0.96 on clean Pt(111) to 0.88 on a p(2&times;2) oxygen pre-covered surface. &copy; 2003 Elsevier B.V. All rights reserved.}, author = {Zhu, Junfa and Kinne, Martin and Fuhrmann, Thomas and Tränkenschuh, Barbara and Denecke, Reinhard and Steinrück, Hans-Peter}, doi = {10.1016/j.susc.2003.10.031}, faupublication = {yes}, journal = {Surface Science}, pages = {410-420}, peerreviewed = {Yes}, title = {{The} adsorption of {NO} on an oxygen pre-covered {Pt}(1 1 1) surface: {In} situ high-resolution {XPS} combined with molecular beam studies}, volume = {547}, year = {2003} } @article{faucris.287840646, abstract = {The targeted enrichment of a Pt complex with an ionic liquid (IL)-derived ligand system in IL solution is demonstrated by using angle-resolved X-ray photoelectron spectroscopy. When the ligand system is complemented with fluorinated side chains, the complex accumulates strongly at the IL/gas interface, while in an equivalent solution of a complex without these substituents no such effect could be observed. This buoy-like behavior induces strong population of the complex at the outermost molecular layer close to surface saturation, which was studied over a range from 5 to 30 %<inf>mol</inf>. The surface enrichment was found to be most efficient at the lowest concentration, which is particularly favorable for catalytic applications such as supported ionic-liquid-phase (SILP) catalysis.}, author = {Hemmeter, Daniel and Kremitzl, Daniel and Schulz, Peter and Wasserscheid, Peter and Maier, Florian and Steinrück, Hans-Peter}, doi = {10.1002/chem.202203325}, faupublication = {yes}, journal = {Chemistry - A European Journal}, keywords = {catalysis; ionic liquids; surface analysis; surface enrichment; X-ray photoelectron spectroscopy (XPS)}, month = {Jan}, note = {CRIS-Team Scopus Importer:2023-01-20}, peerreviewed = {Yes}, title = {{The} {Buoy} {Effect}: {Surface} {Enrichment} of a {Pt} {Complex} in {IL} {Solution} by {Ligand} {Design}}, volume = {29}, year = {2023} } @article{faucris.108398004, abstract = {The adsorption and desorption of CO on stepped Pt(3 2 2) = Pt(S)-[5(1 1 1) &times; (1 0 0)] and Pt(3 5 5) = Pt(S)-[5(1 1 1) &times; (1 1 1)] were investigated using in situ high-resolution X-ray photoelectron spectroscopy at BESSY II, which allows to clearly distinguish between different step and terrace adsorption sites. For the two surfaces, with the same nominal terrace width of five atomic rows, but different step orientation, significant differences are observed. While for Pt(3 5 5) CO adsorption at steps only occurs at on-top sites, on Pt(3 2 2) both step on-top and bridge sites are occupied, albeit with a significantly lower coverage (0.07 vs. 0.13 ML at 200 K). On both surfaces terrace sites are only occupied when the step sites are almost saturated confirming the enhanced binding energy at step sites. CO adsorbed at the (1 1 1) steps on Pt(3 5 5) is more strongly bound than on the (1 0 0) steps on Pt(3 2 2), which is attributed to the different electronic and geometric structure of the steps. The relative occupation of terrace and step sites at a given coverage remains the same between 120 and 290 K on Pt(3 5 5) K, but shows major changes on Pt(3 2 2), between step on-top and bridge sites as well as terrace on-top and bridge sites. On Pt(3 5 5) a smaller CO terrace coverage is found (0.36 vs. 0.40 ML on Pt(3 2 2) at 200 K), mainly due to the lower occupation of terrace bridge sites. For Pt(3 2 2), an ordered adsorbate phase is deduced from a c(4 &times; 2)-like LEED pattern, which indicates adsorbate order beyond the extension of a single terrace. A model for this structure is proposed. &copy; 2006 Elsevier B.V. All rights reserved.}, author = {Tränkenschuh, Barbara and Papp, Christian and Fuhrmann, Thomas and Denecke, Reinhard and Steinrück, Hans-Peter}, doi = {10.1016/j.susc.2006.12.004}, faupublication = {yes}, journal = {Surface Science}, pages = {1108-1117}, peerreviewed = {Yes}, title = {{The} dissimilar twins - a comparative, site-selective in situ study of {CO} adsorption and desorption on {Pt}(3 2 2) and {Pt}(3 5 5)}, volume = {601}, year = {2007} } @article{faucris.114477924, author = {Madix, R.J. and Hamza, Alex and Steinrück, Hans-Peter}, faupublication = {yes}, journal = {Journal of the American Chemical Society}, pages = {150-Coll}, peerreviewed = {Yes}, title = {{The} {Dynamics} of {Alcane} {Activation} on {Nickel} and {Iridium} {Single}-{Crystal} {Surfaces}}, volume = {192}, year = {1986} } @article{faucris.118987484, author = {Hamza, Alex and Steinrück, Hans-Peter and Madix, R.J.}, doi = {10.1116/1.574706}, faupublication = {no}, journal = {Journal of Vacuum Science & Technology A}, pages = {520-521}, peerreviewed = {Yes}, title = {{The} {Dynamics} of {Alkane} {Activation} on {Ni}(100) and {Ir}(110)}, volume = {5}, year = {1987} } @article{faucris.108468404, abstract = {The dissociative adsorption of C-C alkanes on Ir(110)-(1&times;2) was investigated using supersonic molecular beam techniques. Three regimes of reactivity were observed. At incident kinetic energies less than 100 kJ/mol the dissociative adsorption probability for propane and butane increased to about 0.6 with both decreasing surface temperature and decreasing translational energy of the incident molecule suggesting that activation occured via trapping of the alkane on the surface. At kinetic energies below 110 kJ/mol for butane, 90 kJ/mol for propane, 60 kJ/mol for ethane, 40 kJ/mol for methane, and at elevated surface temperatures the reaction probabilities for alkanes were independent of surface temperature and translational energy, but increased significantly with the molecular weight or carbon chain length of the incident alkane. This behavior indicates an unactivated reaction channel for each species except methane. At kinetic energies above 110 kJ/mol for butane, 90 kJ/mol for propane, 60 kJ/mol for ethane, and 40 kJ/mol for methane the initial dissociative sticking probability increased with increasing translational energy and was independent of surface temperature, indicating direct translational activation of the incident alkane. The translational energy required to activate the incident alkane via this channel increased with carbon number or molecular weight, indicative of energy transfer processes that dissipate energy in the reactive collision. The dissipative transfer of translational energy out of the reactive channel via a hard cube collision with the surface accounts qualitatively for the increase in the apparent activation barrier with increasing molecular weight in this activated channel. &copy; 1987 American Institute of Physics.}, author = {Hamza, Alex and Steinrück, Hans-Peter and Madix, R.J.}, faupublication = {no}, journal = {Journal of Chemical Physics}, pages = {6506-6514}, peerreviewed = {Yes}, title = {{The} dynamics of the dissociative adsorption of alkanes on {Ir}(110)}, url = {https://www.scopus.com/record/display.uri?eid=2-s2.0-0001500472&origin=inward}, volume = {86}, year = {1987} } @article{faucris.108468624, abstract = {Benzene adsorption on Ni(111) was studied by ARUPS using linearly polarized synchrotron radiation at various benzene coverages and for benzene coadsorbed with CO. Overall the electronic structure of chemisorbed benzene is found to be very similar for the different benzene coverages and in the presence of coadsorbed CO: only small shifts in the electronic binding energies are observed which are attributed to electrostatic initial state changes. Using dipole selection rules the orientation of the adsorbed benzene molecules is determined to be parallel to the surface for all layers investigated. The molecular symmetry is reduced to C in all cases. The photon energy dependence of the photoionization cross section shows a pronounced resonance of the 2e level at a photon energy of 25 eV (E &asymp; 13 eV); the corresponding electron emission is centered along the surface normal. This resonance is attributed to a shape resonance into an a final state. &copy; 1989.}, author = {Huber, W. and Steinrück, Hans-Peter and Pache, T. and Menzel, Dietrich}, faupublication = {no}, journal = {Surface Science}, pages = {103-126}, peerreviewed = {Yes}, title = {{The} electronic structure and molecular symmetry of pure benzene and benzene coadsorbed with {CO} on {Ni}(111)}, url = {https://www.scopus.com/record/display.uri?eid=2-s2.0-0001129524&origin=inward}, volume = {217}, year = {1989} } @article{faucris.107842064, abstract = {The electronic states of submonolayers and multilayers of cobalt(II) phthalocyanine (CoPc) adsorbed on Ag(111) were examined with photoelectron spectroscopy to obtain insight into the details of the substrate-adsorbate interaction. UV photoelectron spectroscopy (UPS) reveals the presence of two interaction-related valence states in the direct vicinity of the Fermi edge, in agreement with previous DFT calculations. X-ray photoelectron spectra indicate that the substrate-adsorbate interaction results in transfer of electron density from the substrate to the Co(II) ion. Substantial changes in the Co 2p multiplet structure, a spectral pattern induced by the open-shell character of the central Co(II) ion, indicate a complete quenching of the molecular spin. While pristine CoPc molecules are paramagnetic with S = 1/2, molecules in direct contact to the Ag(111) substrate appear to be in a diamagnetic state. &copy; 2012 Elsevier B.V. All rights reserved.}, author = {Schmid, Martin and Kaftan, Andre and Steinrück, Hans-Peter and Gottfried, Michael}, doi = {10.1016/j.susc.2012.02.012}, faupublication = {yes}, journal = {Surface Science}, pages = {945-949}, peerreviewed = {Yes}, title = {{The} electronic structure of cobalt({II}) phthalocyanine adsorbed on {Ag}(111)}, volume = {606}, year = {2012} } @article{faucris.108485124, abstract = {The electronic structure of ethylene adsorbed on Ni(110) has been studied by ARUPS using linearly polarized synchrotron radiation, and by LCGTO-LDF model cluster calculations. The adsorption system has also been characterized by TPD and LEED. The ARUPS measurement were performed for a dilute ethylene layer (&theta; &asymp; 1 2&theta; ), where lateral interactions are not important. From the detailed analysis of the polarization, polar angle and azimuthal dependence of the ARUPS spectra we deduce an orientation of the ethylene molecules with the molecular plane coplanar to the surface and the C-C axis preferentially aligned along the [110] azimuth. The symmetry of the adsorption complex is determined as C . The ethylene &pi;-orbital 1b exhibits a differential shift of 1.1 eV to higher binding energy as compared to the free molecule. The corresponding theoretical value is found to be &sim; 1.7 eV. In the cluster calculations a partial optimization of the adsorbate geometry has been carried out assuming C symmetry. The adsorption bonding is found to be quite similar in &pi; and di-&sigma; coordination, for both cases the &pi; donation to the substrate being stronger than the &pi; backdonation. The &pi; donation is mediated mainly by Nis and p contributions, gp backdonation mostly by Ni d orbitals. The optimized geometry parameters for the &pi;-bonded species are: CC: 1.42 &Aring;: NiC: 2.01 &Aring; tilting of a CH group relative to the (110) crystal plane: 23&deg;. &copy; 1992.}, author = {Weinelt, M. and Huber, W. and Zebisch, P. and Steinrück, Hans-Peter and Pabst, M. and Rösch, Notker}, doi = {10.1016/0039-6028(92)90915-S}, faupublication = {no}, journal = {Surface Science}, pages = {539-554}, peerreviewed = {Yes}, title = {{The} electronic structure of ethylene on {Ni}(110): an experimental and theoretical study}, volume = {271}, year = {1992} } @article{faucris.112618484, abstract = {The growth of thin Cu layers (up to 14 ML) on Ni(111) was studied by temperature-programmed desorption (TPD) of CO and X-ray photoelectron spectroscopy (XPS). CO TPD spectra display desorption features from both nickel- and copper-terminated areas, which are clearly separated in temperature. Using XPS and TPD for titrating the uncovered Ni areas, the quality of the copper layer in the 1 ML range was studied as a function of annealing temperature. We find that a pseudomorphic Cu monolayer on Ni(111) is best produced by evaporating the appropriate amount of Cu onto the cold sample at 100 K, followed by annealing to temperatures around 800 K. This temperature is high enough to convert three-dimensional islands that are found at low temperatures into smooth two-dimensional Cu layers, but low enough to avoid alloying, which is observed for higher annealing temperatures. For higher Cu coverages, annealing to 800 K leads to significant diffusion of Ni atoms into the Cu multilayer. &copy; 2000 Elsevier Science B.V. All rights reserved.}, author = {Koschel, Herbert and Held, Georg and Steinrück, Hans-Peter}, faupublication = {yes}, journal = {Surface Science}, pages = {201-213}, peerreviewed = {Yes}, title = {{The} growth of thin {Cu} layers on {Ni}(111) studied by {CO} titration and photoelectron spectroscopy}, url = {https://www.scopus.com/record/display.uri?eid=2-s2.0-0000303254&origin=inward}, volume = {453}, year = {2000} } @article{faucris.108469064, abstract = {Supersonic molecular beam techniques were used to study the scattering of CO and Ar from clean and CO-covered Ir(110) surfaces over a wide range of kinetic energies of the incident species. The initial sticking coefficient, S, for CO on a clean Ir(110) surface decreases from 0.80 at 2 kcal/mol beam energy to 0.35 at 34 kcal/mol. At each beam enery S is independent of surface temperature in the interval 200&le;T&le;500 K. Scattering of CO from a CO-saturated surface shows a transition from mainly trapping/desorption scattering at low beam energy to direct inelastic scattering at high beam energy. The trapping probability for CO on the covered surface decreases with beam energy. Ar and CO scattering from the covered surface are very similar. The dependence of the trapping probability on beam energy for CO and Ar is identical within the margin of error of the experiment. Comparison of the Ar scattering from the CO-covered surface with that from the clean surface reveals much smaller trapping probabilities for Ar on the clean surface. This indicates that the adsorbed CO layer increases the efficiency of the energy transfer from the gas to the surface. &copy; 1987 Elsevier Science Publishers B.V.}, author = {Steinrück, Hans-Peter and Madix, R.J.}, faupublication = {no}, journal = {Surface Science}, pages = {36-52}, peerreviewed = {Yes}, title = {{The} interaction of {CO} and {Ar} molecular beams with {Ir}(110)}, url = {https://www.scopus.com/record/display.uri?eid=2-s2.0-0000594836&origin=inward}, volume = {185}, year = {1987} } @article{faucris.123156044, abstract = {The interaction of cobalt with an ultrathiri CeO2(111) film on Cu(111) was studied by low energy ion scattering spectroscopy and X-ray photoelectron spectroscopy. At room temperature, Co grows three-dimensionally on the ceria film. For small Co coverages (0.2 ML), oxidation to Co2+ occurs together with the formation Of Ce3+ in the ceria. At higher Co coverages (07 and 2 ML), an increasing fraction of Co remained Metallic after deposition. Annealing to higher temperatures induced diffusion of Co2+ ions into the ceria film, and for metallic Co, presumably agglomeration occurs. At T &gt;= 800 K, oxidation of significant amounts of Co-0 to Co2+ is found, along with diffusion, into the ceria. film, and partly also in the copper crystal underneath. On a reduced CeOx surface, the redox reaction between cobalt and cerium was hindered, which, in turn, slowed down cobalt migration into the ceria film.}, author = {Vari, Gabor and Ovari, Laszlo and Papp, Christian and Steinrück, Hans-Peter and Kiss, Janos and Konya, Zoltan}, doi = {10.1021/acs.jpcc.5b00626}, faupublication = {yes}, journal = {Journal of Physical Chemistry C}, pages = {9324-9333}, peerreviewed = {Yes}, title = {{The} {Interaction} of {Cobalt} with {CeO2}(111) {Prepared} on {Cu}(111)}, volume = {119}, year = {2015} } @article{faucris.319722263, abstract = {For the transition to renewable energy sources, novel energy storage materials are more important than ever. This review addresses so-called molecular solar thermal (MOST) systems, which appear very promising since they combine light harvesting and energy storing in one-photon one-molecule processes. The focus is on norbornadiene (NBD), a particularly interesting candidate, which is converted to the strained valence isomer quadricyclane (QC) upon irradiation. The stored energy can be released on demand. The energy-releasing cycloreversion from QC to NBD can be initiated by a thermal, catalytic, or electrochemical trigger. The reversibility of the energy storage and release cycles determines the general practicality of a MOST system. In the search for derivatives, which enable large-scale applications, fundamental surface science studies help to assess the feasibility of potential substituted NBD/QC couples. We include investigations under well-defined ultra-high vacuum (UHV) conditions as well as experiments in liquid phase. Next to the influence of the catalytically active surfaces on the isomerization between the two valence isomers, information on adsorption geometries, thermal stability limits, and reaction pathways of the respective molecules are discussed. Moreover, laboratory-scaled test devices demonstrate the proof of concept in various areas of application.}, author = {Hemauer, Felix and Steinrück, Hans-Peter and Papp, Christian}, doi = {10.1002/cphc.202300806}, faupublication = {yes}, journal = {ChemPhysChem}, keywords = {energy storage; heterogeneous catalysis; MOST systems; norbornadiene; surface science}, note = {CRIS-Team Scopus Importer:2024-03-15}, peerreviewed = {Yes}, title = {{The} {Norbornadiene}/{Quadricyclane} {Pair} as {Molecular} {Solar} {Thermal} {Energy} {Storage} {System}: {Surface} {Science} {Investigations}}, year = {2024} } @article{faucris.112922524, abstract = {Angle-resolved UV photoelectron spectroscopy (ARUPS) using linearly polarized synchrotron radiation is used to determine the orientation of benzene molecules on two modifications of the pseudomorphic Ni/Cu(111) layer, the Ni-terminated adlayer and the Cu-terminated Ni sublayer. It is found that the molecules adsorb with their C-H bonds 30&deg; off the close-packed substrate rows (&sigma; orientation) on the Ni adlayer whereas no preferential orientation was found for the Cu-terminated Ni sublayer. For these and other close-packed mono- and bimetallic surfaces involving Cu, Ni and Ru, the correlation between adsorption geometry and reactivity of benzene is explored in connection with temperature-programmed desorption (TPD). Like for the Ni/Cu(111) sublayer, no preferential lateral orientation and a weak bond is found on most other Cu-terminated surfaces at 80 K. This goes along with the absence of any dissociation on these surfaces. Only on the stretched 1 ML Cu/Ru(0001) surface is the substrate-benzene bond strong enough to induce a clear preferential orientation (&sigma; with C-H bonds parallel to the close-packed rows) but still too weak to induce dissociation. The same orientation was found for the saturated benzene layer on Ni(111) where the molecules also do not dissociate. Dissociation is, however, observed for the saturation coverage of benzene on the Ni/Cu(111) adlayer and for low benzene coverages on Ni(111). On these surfaces the azimuthal orientation of the benzene molecules is &sigma;, i.e. rotated by 30&deg; with respect to the close-packed rows.}, author = {Koschel, Herbert and Held, Georg and Steinrück, Hans-Peter}, doi = {10.1142/S0218625X99000950}, faupublication = {yes}, journal = {Surface Review and Letters}, pages = {893-901}, peerreviewed = {Yes}, title = {{The} orientation of benzene on bimetallic surfaces}, volume = {6}, year = {1999} } @article{faucris.108485784, abstract = {The electronic structure of ethylene oxide adsorbed at Ni(110) has been calculated by the LCGTO-DF method using cluster models of various adsorption sites. At the local density level of theory a weak binding of the adsorbate to the substrate is found, but a repulsive interaction results for a gradient corrected energy functional. No major differences are calculated between the one-electron level spectrum of gas phase and of adsorbed ethylene oxide molecules. A new assignment of the photoelectron spectrum of ethylene oxide adsorbed at metal surfaces is proposed which differs from previous experimental and theoretical investigations of ethylene oxide adsorbed at various metal surfaces. &copy; 1995.}, author = {Ulbricht, P. and Häberlen, O.D. and Weinelt, M. and Steinrück, Hans-Peter and Rösch, Notker}, doi = {10.1016/0039-6028(94)00773-X}, faupublication = {no}, journal = {Surface Science}, pages = {53-58}, peerreviewed = {Yes}, title = {{The} photoelectron spectrum of ethylene oxide adsorbed at metal surfaces: a density functional model cluster study of {C2H4O} {Ni}(110)}, volume = {326}, year = {1995} } @article{faucris.106903544, abstract = {We show that both tetraphenylphosphonium bis(trifluoromethylsulfonyl)imide ([PPh4][NTf2]) and Cs[NTf2] are low melting salts of exceptionally high and also very similar thermal stability. This similarity indicates that the thermal stability is dominated by the anion. Moreover, eutectic mixtures of [PPh4][NTf2] and Cs[NTf2] with melting points below 100 degrees C are presented. Surface analysis of the latter in the liquid state reveals a surprising depletion of (PPh4](+) ions from the surface.}, author = {Scheuermeyer, Marlene and Kusche, Matthias Manfred and Agel, Friederike and Schreiber, Patrick and Maier, Florian and Steinrück, Hans-Peter and Davis, James H. and Heym, Florian and Jess, Andreas and Wasserscheid, Peter}, doi = {10.1039/c6nj00579a}, faupublication = {yes}, journal = {New Journal of Chemistry}, pages = {7157-7161}, peerreviewed = {Yes}, title = {{Thermally} stable bis(trifluoromethylsulfonyl)imide salts and their mixtures}, volume = {40}, year = {2016} } @article{faucris.113333924, abstract = {We have studied the thermal stability of ultrathin platinum films on a rutile TiO(110) surface, using low energy ion scattering (LEIS) and X-ray photoelectron spectroscopy (XPS). At room temperature, Pt grows in three-dimensional islands on the TiO surface, with little indication of an interface reaction. Upon annealing to temperatures above 450 K in UHV, encapsulation of the Pt islands by Ti suboxides is observed; the rate of this process increases with annealing temperature and decreases with island thickness. The Ti layer on top of the Pt islands is identified as a reduced Ti species (1 &le; n &le; 3) with the degree of reduction depending on the thickness of the Pt islands. These results are discussed in the framework of the strong metal-support interaction (SMSI) effect. &copy; 1995.}, author = {Pesty, François and Steinrück, Hans-Peter and Madey, Theodore E.}, doi = {10.1016/0039-6028(95)00605-2}, faupublication = {no}, journal = {Surface Science}, pages = {83-95}, peerreviewed = {Yes}, title = {{Thermal} stability of {Pt} films on {TiO2}(110): evidence for encapsulation}, volume = {339}, year = {1995} } @article{faucris.108471484, abstract = {We present a molecular beam study on the dissociative sticking coefficient for CO on a Ni(100) surface. In the range from 1.6 to 20 kcal/mol the observed dissociative sticking coefficient at a surface temperature of 500 K is 0.02 and independent of beam energy. Investigations on a sputter-damaged surface result in a sticking coefficient of 0.40, again independent of beam energy. The observed behavior can be explained by CO dissociation at defect sites. &copy; 1986.}, author = {Steinrück, Hans-Peter and D'Evelyn, M.P. and Madix, R.J.}, faupublication = {no}, journal = {Surface Science}, peerreviewed = {Yes}, title = {{The} role of defects in the dissociative adsorption of {CO} on {Ni}(100)}, url = {https://www.scopus.com/record/display.uri?eid=2-s2.0-0001483665&origin=inward}, volume = {172}, year = {1986} } @article{faucris.120682584, abstract = {On a smooth Ni(111) surface both the &beta; and the &beta; state show activated adsorption. The desorption flux is highly peaked towards the surface normal. Defects introduce non-activated adsorption sites which lower the desorption temperatures in flash desorption. At the same time a cosine dependence of the desorption flux is obtained. Because of its small sticking coefficient the &beta; state is already influenced by small defect concentrations; the &beta; state is only affected on highly defective surfaces. &copy; 1987 Elsevier Science Publishers B.V.}, author = {Rendulic, K.D. and Winkler, A. and Steinrück, Hans-Peter}, faupublication = {no}, journal = {Surface Science}, pages = {469-478}, peerreviewed = {Yes}, title = {{The} role of surface defects in the adsorption and sesorption of hydrogen on {Ni}(111)}, url = {https://www.scopus.com/record/display.uri?eid=2-s2.0-0000152646&origin=inward}, volume = {185}, year = {1987} } @article{faucris.108471704, abstract = {The sticking coefficient of H/Ni(111) changes proportionally to the beam energy. The angular distribution of the probability of adsorption varies with cos&theta;; the angular distribution of desorption is found to change as cos&theta; at 300 K. Assuming validity of detailed balancing, the adsorption data suggest an energy distribution for desorption which agrees with existing time-of-flight measurements. &copy; 1985.}, author = {Steinrück, Hans-Peter and Rendulic, K.D. and Winkler, A.}, faupublication = {no}, journal = {Surface Science}, pages = {99-108}, peerreviewed = {Yes}, title = {{The} sticking coefficient of {H2} on {Ni}(111) as a function of particle energy and angle of incidence: {A} test of detailed balancing}, url = {https://www.scopus.com/record/display.uri?eid=2-s2.0-0002012380&origin=inward}, volume = {154}, year = {1985} } @article{faucris.108398884, abstract = {The surface geometries of the p(7&times;7)R19&deg;-(4CO) and c(2 &times; 4)-(2CO) layers on Ni{1 1 1} and the clean Ni{1 1 1} surface were determined by low energy electron diffraction structure analysis. For the clean surface small but significant contractions of d and d (both 2.02 &Aring;) were found with respect to the bulk interlayer distance (2.03 &Aring;). In the c(2 &times; 4)-(2CO) structure these distances are expanded, with values of d = 2.08 &Aring; and d = 2.06 &Aring; and buckling of 0.08 and 0.02 &Aring;, respectively, in the first and second layer. CO resides near hcp and fcc hollow sites with relatively large lateral shifts away from the ideal positions leading to unequal C-Ni bond lengths between 1.76 and 1.99 &Aring;. For the p(7&times;7)R19&deg;-(4CO) layer two best fit geometries were found, which agree in most of their atomic positions, except for one out of four CO molecules, which is either near atop or between bridge and atop. The remaining three molecules reside near hcp and fcc sites, again with large lateral deviations from their ideal positions. The average C-Ni bond length for these molecules is, however, the same as for CO on hollow sites at low coverage. The average C-Ni bond length at hollow sites, the interlayer distances, and buckling in the first Ni layer are similar to the c(2 &times; 4)-(2CO) geometry, only the buckling in the second layer (0.08 &Aring;) is significantly larger. Lateral and vertical shifts of the Ni atoms in the first layer lead to unsymmetric environments for the CO molecules, which can be regarded as an imprint of the chiral p(7&times;7)R19&deg; lattice geometry onto the substrate. &copy; 2004 Elsevier B.V. All rights reserved.}, author = {Braun, Wolfgang and Steinrück, Hans-Peter and Held, Georg}, doi = {10.1016/j.susc.2004.11.034}, faupublication = {yes}, journal = {Surface Science}, keywords = {nickel;carbon monoxide;low energy electron diffraction (LEED)}, pages = {343-357}, peerreviewed = {Yes}, title = {{The} surface geometries of the medium and high coverage carbon monoxide structures c(2 × 4)-({2CO}) and p(√7 × √7){R19}°-({4CO}) on {Ni}{1 1 1}}, volume = {575}, year = {2005} } @article{faucris.121336864, abstract = {A combination of photoelectron spectroscopy, temperature programmed desorption and low energy electron diffraction structure determinations have been applied to study the p(2 &times; 2) structures of pure hydrogen and co-adsorbed hydrogen and CO on Ni{1 1 1}. In agreement with earlier work atomic hydrogen is found to adsorb on fcc and hcp sites in the pure layer with H-Ni bond lengths of 1.74 &Aring;. The substrate interlayer distances, d = 2.05 &Aring; and d = 2.06 &Aring;, are expanded with respect to clean Ni{1 1 1} with buckling of 0.04 &Aring; in the first layer. In the co-adsorbed phase CO occupies hcp sites and only the hydrogen atoms on fcc sites remain on the surface. d is even further expanded to 2.08 &Aring; with buckling in the first and second layer of 0.06 and 0.02 &Aring;, respectively. The C-O, C-Ni, and H-Ni bond lengths are within the range of values also found for the pure adsorbates. &copy; 2004 Elsevier B.V. All rights reserved.}, author = {Braun, Wolfgang and Steinrück, Hans-Peter and Held, Georg}, doi = {10.1016/j.susc.2004.10.029}, faupublication = {yes}, journal = {Surface Science}, pages = {193-204}, peerreviewed = {Yes}, title = {{The} surface geometry of carbonmonoxide and hydrogen co-adsorbed on {Ni}{1 1 1}}, volume = {574}, year = {2005} } @article{faucris.120341584, abstract = {Low energy electron diffraction (LEED) structure determinations have been performed for the p(2 x 2) structures of pure oxygen and oxygen co-adsorbed with CO on Ni {111}. Optimisation of the non-geometric parameters led to very good agreement between experimental and theoretical IV-curves and hence to a high accuracy in the structural parameters. In agreement with earlier work atomic oxygen is found to adsorb on fcc sites in both structures. In the co-adsorbed phase CO occupies atop sites. The positions of the substrate atoms are almost identical, within 0.02 &Aring;, in both structures, implying that the interaction with oxygen dominates the arrangement of Ni atoms at the surface.}, author = {Braun, Wolfgang and Steinrück, Hans-Peter and Held, Georg}, doi = {10.1524/zpch.218.8.915.35977}, faupublication = {yes}, journal = {Zeitschrift für Physikalische Chemie-International Journal of Research in Physical Chemistry & Chemical Physics}, pages = {915-927}, peerreviewed = {Yes}, title = {{The} surface geometry of carbon monoxide and oxygen co-adsorbed on {Ni}{111}}, volume = {218}, year = {2004} } @article{faucris.121306284, abstract = {The chemical bond between an adsorbed, laterally coordinated metal ion and a metal surface is affected by an additional axial ligand on the metal ion. This surface analogon of the trans effect was studied in detail using monolayers of various M(II)-tetraphenylporphyrins (MTTPs, M = Fe, Co, Zn) and their nitrosyl complexes on a Ag(111) surface. X-ray photoelectron spectroscopy (XPS) shows that the oxidation state of the Fe and Co (but not Zn) ions in the MTPP monolayers is reduced because of the interaction with the substrate. This partial reduction is accompanied by the appearance of new valence states in the UV photoelectron and scanning tunneling spectra (UPS and STS), revealing the covalent character of the ion-substrate bond. Subsequent coordination of nitric oxide (NO) to the metal ions (Fe, Co) reverses these surface-induced effects, resulting in an increase of the oxidation states and the disappearance of the new valence states. Removal of the NO ligands by thermal desorption restores the original spectroscopic features, indicating that the described processes are fully reversible. The NO coordination also changes the spin state and thus the magnetic properties of the metal ions. Density-functional theory (DFT) calculations on model systems provide structural and energetic data on the adsorbed molecules and the surface chemical bond. The calculations reveal that competition effects, similar to the trans effect, play a central role and lead to a mutual interference of the two axial ligands, NO and Ag, and their bonds to the metal center. These findings have important implications for sensor technology and catalysis using supported planar metal complexes, in which the activity of the metal center is sensitively influenced by the substrate. &copy; 2011 American Chemical Society.}, author = {Hieringer, Wolfgang and Flechtner, Ken and Kretschmann, Andreas and Seufert, Knud and Auswärter, Willi and Barth, Johannes V. and Görling, Andreas and Steinrück, Hans-Peter and Gottfried, Michael}, doi = {10.1021/ja1093502}, faupublication = {yes}, journal = {Journal of the American Chemical Society}, pages = {6206-6222}, peerreviewed = {Yes}, title = {{The} surface trans effect: {Influence} of axial ligands on the surface chemical bonds of adsorbed metalloporphyrins}, volume = {133}, year = {2011} } @article{faucris.117430544, abstract = {The investigation of nickel phosphide (Ni5P4) as a catalyst for the hydrogen (HER) and oxygen evolution reaction (OER) in strong acidic and alkaline environment is described. The catalyst can be grown in a 3D hierarchical structure directly on a nickel substrate, thus making it an ideal candidate for practical water splitting devices. The activity of the catalyst towards the HER, together with its high stability especially in acidic solution, makes it one of the best non-noble materials described to date. Furthermore, Ni5P4 was investigated in the OER and showed activity superior to pristine nickel or platinum. The practical relevance of Ni5P4 as a bifunctional catalyst for the overall water splitting reaction was demonstrated, with 10 mA cm(-2) achieved below 1.7 V.}, author = {Ledendecker, Marc and Calderon, Sandra Krick and Papp, Christian and Steinrück, Hans-Peter and Antonietti, Markus and Shalom, Menny}, doi = {10.1002/anie.201502438}, faupublication = {yes}, journal = {Angewandte Chemie International Edition}, keywords = {ceramics;hydrogen evolution reaction;nickel phosphides;oxygen evolution reaction;water splitting reaction}, pages = {12361-12365}, peerreviewed = {Yes}, title = {{The} {Synthesis} of {Nanostructured} {Ni5P4} {Films} and their {Use} as a {Non}-{Noble} {Bifunctional} {Electrocatalyst} for {Full} {Water} {Splitting}}, volume = {54}, year = {2015} } @article{faucris.108404824, abstract = {The thermal chemistry of saturated layers of acetylene and ethylene on Ni(100) was studied using in situ synchrotron x-ray photoelectron spectroscopy. The vibrational excitation of the C-H mode in gas phase ethylene was in the range of 410-420 meV, higher than the adsorbed states. It was concluded that the two peaks at 283.74 and 284.07 eV represented a single molecularly adsorbed ethylene species.}, author = {Neubauer, Ralf and Whelan, Caroline and Denecke, Reinhard and Steinrück, Hans-Peter}, doi = {10.1063/1.1582432}, faupublication = {yes}, journal = {Journal of Chemical Physics}, pages = {1710-1718}, peerreviewed = {Yes}, title = {{The} thermal chemistry of saturated layers of acetylene and ethylene on {Ni}(100) studied by in situ synchrotron x-ray photoelectron spectroscopy}, volume = {119}, year = {2003} } @article{faucris.120341804, abstract = {The oxygen chemisorption and oxidation of Ni monolayers on Cu(111) were studied by high resolution XPS. As a result, new insight in the electronic state of the top-most surface atoms during adsorption and reaction of molecules which cannot be retrieved from single crystal surfaces because of the dominating bulk signal was obtained.}, author = {Domnick, Ralph and Held, Georg and Witte, Patrick and Steinrück, Hans-Peter}, doi = {10.1063/1.1379534}, faupublication = {yes}, journal = {Journal of Chemical Physics}, pages = {1902-1908}, peerreviewed = {Yes}, title = {{The} transition from oxygen chemisorption to oxidation of ultra-thin {Ni} layers on {Cu}(111)}, volume = {115}, year = {2001} } @article{faucris.113118324, abstract = {The resolution of focused electron beam induced processing techniques is limited by electron scattering processes. General wisdom holds that using a membrane, this can be effectively improved due to a cutoff of the electron interaction volume and thus diminished proximity effects. Recently, we demonstrated that in contrast to the expectation, proximity effects can be indeed larger on a 200nm silicon nitride membrane than on the respective bulk substrate, due to charging-induced surface activation. Herein, we expand these investigations on proximity effects in electron beam-induced surface activation to other substrates and to electron beam-induced deposition followed by autocatalytic growth. &copy; 2012 IOP Publishing Ltd.}, author = {Walz, Marie-Madeleine and Vollnhals, Florian and Rietzler, Florian and Schirmer, Michael and Kunzmann, Andreas and Steinrück, Hans-Peter and Marbach, Hubertus}, doi = {10.1088/0022-3727/45/22/225306}, faupublication = {yes}, journal = {Journal of Physics D-Applied Physics}, peerreviewed = {Yes}, title = {{Thin} membranes versus bulk substrates: {Investigation} of proximity effects in focused electron beam-induced processing}, volume = {45}, year = {2012} } @article{faucris.120453344, abstract = {The adsorption of benzene on the reconstructed Pt (110) 1 &times; 2 surface was studied by temperature-programmed desorption (TPD), low-energy electron diffraction (LEED), angle-resolved UV photoemission (ARUPS) and near-edge X-ray absorption spectroscopy (NEXAFS). At 100 K, benzene is molecularly adsorbed on the Pt (110) 1 &times; 2 surface. The saturated layer is disordered and corresponds to a coverage of &sim;0.28 ML. Annealing to 280 K leads to partial benzene desorption and to the formation of a well-ordered (4 &times; 2) layer (relative to the unreconstructed surface) with a coverage of 0.25 ML. The missing ((2n + 1)/4, 0) adsorbate LEED spots along [11̄0] indicate a glide plane in the adsorbate structure and the existence of two molecules per unit cell. In this layer, benzene adsorbs with the molecular plane tilted by &sim;30&deg; in the [001] direction, as determined from ARUPS and NEXAFS. This geometry corresponds to a nearly flat adsorption on the (111) microfacets of the troughs of the reconstructed surface. The molecules have a well-defined azimuthal orientation with a C-H bond along the [11̄0] azimuth. For dilute layers (&theta; = 0.12 ML) and a disordered layer with the same coverage as the ordered layer (&theta; = 0.25 ML), the molecules are also tilted into the troughs, a preferential azimuthal orientation is, however, not observed. &copy; 1998 Elsevier Science B.V.}, author = {Zebisch, P. and Stichler, M. and Trischberger, P. and Weinelt, M. and Steinrück, Hans-Peter}, faupublication = {no}, journal = {Surface Science}, pages = {61-77}, peerreviewed = {Yes}, title = {{Tilted} adsorption of benzene on {Pt} (110) 1 × 2}, url = {https://www.scopus.com/record/display.uri?eid=2-s2.0-0031680478&origin=inward}, volume = {396}, year = {1998} } @article{faucris.263978963, abstract = {We deposited defined amounts of [C₁C₁Im][Tf₂N] on Au(111) at different temperatures and investigated the morphology and wetting behavior of the deposited films by atomic force microscopy. For multilayer coverages, we observe a drastically different growth behavior when comparing deposition at room temperature (RT) and deposition below 170 K followed by slow annealing to RT. Upon deposition at RT, we find the formation of 2–30 nm high and 50–500 nm wide metastable 3D droplets on top of a checkerboard-type wetting layer. These droplets spread out into stable 2D bilayers, on the time scale of hours and days. The same 2D bilayer structure is obtained after deposition below 170 K and slow annealing to RT. We present a statistical analysis on the time-dependent changes of the shape and volume of the 3D droplets and the 2D bilayers. We attribute the stabilization of the 2D bilayers on the wetting layer and on already formed bilayers to the high degree of order in these layers. Notably, the transformation process from the 3D droplets to 2D bilayer islands is accelerated by tip effects and also X-ray radiatio}, author = {Meusel, Manuel and Gezmis, Emine and Jaekel, Simon and Lexow, Matthias and Bayer, Andreas and Maier, Florian and Steinrück, Hans-Peter}, doi = {10.1021/acs.jpcc.1c06613}, faupublication = {yes}, journal = {Journal of Physical Chemistry C}, peerreviewed = {Yes}, title = {{Time}- and {Temperature}-{Dependent} {Growth} {Behavior} of {Ionic} {Liquids} on {Au}(111) {Studied} by {Atomic} {Force} {Microscopy} in {Ultrahigh} {Vacuum}}, year = {2021} } @article{faucris.202403208, abstract = {Various amounts of the ionic liquids (ILs) [C(1)C(1)Im][Tf2N] and [C(8)C(1)Im][Tf2N] were deposited in vacuo by physical vapour deposition (PVD) on single crystalline Ag(111) at room temperature and subsequently monitored by angle-resolved X-ray photoelectron spectroscopy (ARXPS) as a function of time. For very low coverages of up to one closed molecular layer, an initial wetting layer was rapidly formed for both ILs. Deposition of higher amounts of [C(1)C(1)Im][Tf2N] revealed an initial three-dimensional film morphology. On the time scale of hours, characteristic changes of the XPS signals were observed. These are interpreted as island spreading and a transformation towards a nearly two dimensional [C(1)C(1)Im][Tf2N] film as the final state. In contrast, a film morphology close to 2D was found from the very beginning for [C(8)C(1)Im][Tf2N] deposited on Ag(111) demonstrating the influence of the alkyl chain length on the growth kinetics. These studies also highlight the suitability of time-resolved ARXPS for the investigation of IL/solid interfaces, which play a crucial role in IL thin film applications such as in catalysis, sensor, lubrication, and coating technologies.}, author = {Lexow, Matthias and Talwar, Timo and Heller, Bettina and May, Benjamin and Bhuin, Radha Gobinda and Maier, Florian and Steinrück, Hans-Peter}, doi = {10.1039/c8cp01411f}, faupublication = {yes}, journal = {Physical Chemistry Chemical Physics}, pages = {12929-12938}, peerreviewed = {Yes}, title = {{Time}-dependent changes in the growth of ultrathin ionic liquid films on {Ag}(111)}, volume = {20}, year = {2018} } @article{faucris.108275904, abstract = {Aiming at a better understanding of the interaction of ionic liquid (IL) thin films with oxide supports, we have performed a model study under ultrahigh vacuum (UHV) conditions. We apply infrared reflection absorption spectroscopy (IRAS) in combination with density functional theory (DFT). Thin films of 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide [BMIM][Tf N] are grown on an atomically flat, well-ordered alumina film on NiAl(110) using a novel UHV-compatible evaporator. Time-resolved IRAS measured during the growth and subsequent thermal desorption points toward reversible molecular adsorption and desorption. There was no indication of decomposition. The vibrational bands are assigned with the help of DFT calculations. Strong relative intensity changes in individual [TfN] bands are observed in the monolayer region. This indicates pronounced orientation effects for the anion. The adsorption geometry of [TfN] is determined on the basis of a detailed comparison with DFT. The results suggest that [TfN] anions adopt a cis conformation in the submonolayer region. They adsorb in a slightly tilted orientation with respect to the surface, mainly interacting with the support via the sulfonyl groups. &copy; 2010 American Chemical Society.}, author = {Sobota, Marek and Nikiforidis, Ioannis and Hieringer, Wolfgang and Paape, Natalia and Happel, Markus and Steinrück, Hans-Peter and Görling, Andreas and Wasserscheid, Peter and Laurin, Mathias and Libuda, Jörg}, doi = {10.1021/la904319h}, faupublication = {yes}, journal = {Langmuir}, pages = {7199-7207}, peerreviewed = {Yes}, title = {{Toward} ionic-liquid-based model catalysis: {Growth}, orientation, conformation, and interaction mechanism of the [{Tf2N}]- anion in [{BMIM}][{Tf2N}] thin films on a well-ordered alumina surface}, volume = {26}, year = {2010} } @article{faucris.108276344, abstract = {Ten [CCIm] (1-methyl-3- octylimidazolium)-based ionic liquids with anions Cl, Br , I, [NO], [BF] , [TfO], [PF], [Tf N], [PfN], and [FAP] (TfO = trifluoromethylsulfonate, TfN = bis(trifluoromethylsulfonyl) imide, PfN = bis(pentafluoroethylsulfonyl)imide, FAP = tris-(pentafluoroethyl)trifluorophosphate) and two [CC CIm] (1,2-dimethyl-3-octylimidazolium)-based ionic liquids with anions Br and [TfN] were investigated by using X-ray photoelectron spectroscopy (XPS), NMR spectroscopy and theoretical calculations. WhileH NMR spectroscopy is found to probe very specifically the strongest hydrogen-bond interaction between the hydrogen attached to the C position and the anion, a comparative XPS study provides first direct experimental evidence for cation-anion charge-transfer phenomena in ionic liquids as a function of the ionic liquid&#39;s anion. These charge-transfer effects are found to be surprisingly similar for [CCIm] and [CCC Im] salts of the same anion, which in combination with theoretical calculations leads to the conclusion that hydrogen bonding and charge transfer occur independently from each other, but are both more pronounced for small and more strongly coordinating anions, and are greatly reduced in the case of large and weakly coordinating anions. &copy; 2010 Wiley-VCH Verlag GmbH &amp; Co. KGaA, Weinheim.}, author = {Cremer, Till and Kolbeck, Claudia and Lovelock, Kevin and Paape, Natalia and Woelfel, Rene and Schulz, Peter and Wasserscheid, Peter and Weber, Henry and Thar, Jens and Kirchner, Barbara and Maier, Florian and Steinrück, Hans-Peter}, doi = {10.1002/chem.201001032}, faupublication = {yes}, journal = {Chemistry - A European Journal}, pages = {9018-9033}, peerreviewed = {Yes}, title = {{Towards} a molecular understanding of cation-anion interactions-{Probing} the electronic structure of imidazolium ionic liquids by {NMR} spectroscopy, {X}-ray photoelectron spectroscopy and theoretical calculations}, volume = {16}, year = {2010} } @article{faucris.107813464, abstract = {We demonstrate that Cu(111) surfaces pre-covered with a submonolayer of copper oxide or metallic nickel are suitable model-templates for the selective adsorption and/or localized functionalization of functional molecules such as different free base porphyrins and metalloporphyrins. The oxide/Cu(111) model-template is able to steer the adsorption of tetraphenylporphyrins (TPP): 2HTPP selectively adsorbs on the bare Cu areas, and for CoTPP anchoring at the rim of the copper oxide islands is found. On the Ni/Cu(111) model-template TPP molecules are pinned on the Ni areas while they are mobile on the bare Cu surface. Interestingly, adsorption of free base octaethylporphyrin on Ni/Cu(111) leads to a local functionalization, namely the metalation to NiOEP on the Ni areas. Model-template preparation and characterization by scanning tunneling microscopy is performed at room temperature. &copy; 2013 IOP Publishing Ltd.}, author = {Ditze, Stefanie and Röckert, Michael and Buchner, Florian and Zillner, Elisabeth and Stark, Michael Werner and Steinrück, Hans-Peter and Marbach, Hubertus}, doi = {10.1088/0957-4484/24/11/115305}, faupublication = {yes}, journal = {Nanotechnology}, peerreviewed = {Yes}, title = {{Towards} the engineering of molecular nanostructures: {Local} anchoring and functionalization of porphyrins on model-templates}, volume = {24}, year = {2013} } @article{faucris.108276784, abstract = {The thickness of the reaction zone at the interface between calcium and regioregular poly(3-hexylthiophene), which is one of the best performing metal/polymer combinations in photovoltaic devices, depends critically on the temperature of the polymer during the initial phase of metal deposition. It is shown that deposition at 130 K reduces the thickness of the reaction zone, an effect that also persists after warming to room temperature. &copy; 2010 American Chemical Society.}, author = {Bebensee, Fabian and Schmid, Martin and Steinrück, Hans-Peter and Campbell, C. T. and Gottfried, Michael}, doi = {10.1021/ja104029r}, faupublication = {yes}, journal = {Journal of the American Chemical Society}, pages = {12163-12165}, peerreviewed = {Yes}, title = {{Toward} well-defined metal-polymer interfaces: {Temperature}-controlled suppression of subsurface diffusion and reaction at the calcium/poly(3- {Hexylthiophene}) interface}, volume = {132}, year = {2010} } @article{faucris.122819004, abstract = {The control of order in organic semiconductor systems is crucial to achieve desired properties in electronic devices. We have studied the order in fullerene functionalized self-assembled monolayers by mixing the active molecules with supporting alkyl phosphonic acids of different chain length. By adjusting the length of the molecules, structural modifications of the alignment of the C60 head groups within the SAM can be tuned in a controlled way. These changes on the sub-nanometre scale were analysed by grazing incidence X-ray diffraction and X-ray reflectivity. To study the electron transport properties across these layers, self-assembled monolayer field-effect transistors (SAMFETs) were fabricated containing only the single fullerene monolayer as semiconductor. Electrical measurements revealed that a high 2D crystalline order is not the only important aspect. If the fullerene head groups are too confined by the supporting alkyl phosphonic acid molecules, defects in the crystalline C60 film, such as grain boundaries, start to strongly limit the charge transport properties. By close interpretation of the results of structural investigations and correlating them to the results of electrical characterization, an optimum chain length of the supporting alkyl phosphonic acids in the range of C10 was determined. With this study we show that minor changes in the order on the sub-nanometre scale, can strongly influence electronic properties of functional self-assembled monolayers.}, author = {Schmaltz, Thomas and Khassanov, Artöm and Steinrück, Hans-Peter and Magerl, Andreas and Hirsch, Andreas and Halik, Marcus}, doi = {10.1039/C4NR03557G}, faupublication = {yes}, journal = {Nanoscale}, pages = {13022 - 13027}, peerreviewed = {Yes}, title = {{Tuning} the molecular order of {C60}-based self-assembled monolayers in field-effect transistors}, url = {http://pubs.rsc.org/en/content/articlelanding/2014/nr/c4nr03557g#!divAbstract}, volume = {6}, year = {2014} } @article{faucris.107814344, abstract = {We introduce a new approach for ultrafast in situ high-resolution X-ray photoelectron spectroscopy (XPS) to study surface processes and reaction kinetics on the microsecond timescale. The main idea is to follow the intensity at a fixed binding energy using a commercial 7 channeltron electron analyzer with a modified signal processing setup. This concept allows for flexible switching between measuring conventional XP spectra and ultrafast XPS. The experimental modifications are described in detail. As an example, we present measurements for the adsorption and desorption of CO on Pt(111), performed at the synchrotron radiation facility BESSY II, with a time resolution of 500 &mu;s. Due to the ultrafast measurements, we are able to follow adsorption and desorption in situ at pressures of 2 &times; 10 mbar and temperatures up to 500 K. The data are consistently analyzed using a simple model in line with data obtained with conventional fast XPS at temperatures below 460 K. Technically, our new approach allows measurement on even shorter timescales, down to 20 &mu;s. &copy; 2013 AIP Publishing LLC.}, author = {Höfert, Oliver and Gleichweit, Christoph and Steinrück, Hans-Peter and Papp, Christian}, doi = {10.1063/1.4821496}, faupublication = {yes}, journal = {Review of Scientific Instruments}, peerreviewed = {Yes}, title = {{Ultrafast} x-ray photoelectron spectroscopy in the microsecond time domain}, volume = {84}, year = {2013} } @article{faucris.120965724, abstract = {The growth of ultrathin platinum films on a rutile TiO2(110) surface has been studied using low-energy ion scattering and x-ray photoelectron spectroscopy. In the temperature range between 160 and 420 K, Pt grows in three-dimensional islands on the TiO2 surface with the size of the islands increasing with increasing surface temperature and without indication of an interface reaction. Evaporation of Pt in the presence of CO leads to a significantly higher degree of wetting. This behavior is attributed to a chemisorption-induced surfactant effect. &copy; 1995 The American Physical Society.}, author = {Steinrück, Hans-Peter and Pesty, François and Zhang, Lei and Madey, Theodore E.}, doi = {10.1103/PhysRevB.51.2427}, faupublication = {no}, journal = {Physical Review B}, pages = {2427-2439}, peerreviewed = {Yes}, title = {{Ultrathin} films of {Pt} on {TiO2}(110): {Growth} and chemisorption-induced surfactant effects}, volume = {51}, year = {1995} } @article{faucris.240989121, abstract = {The interface of ionic liquids (ILs) with solid surfaces is of pivotal interest for many applications, ranging from sensors, lubrication, separation technology, and electronics to electrochemistry and catalysis. We present a short review on ultrathin layers of ionic liquids on metal surfaces using a surface science approach. We mainly focus on specific examples of imidazolium-based ionic liquids on Ag(111) and Au(111) studied by angle-resolved X-ray photoelectron spectroscopy, and relate the obtained results to existing literature. We address a variety of phenomena on the molecular level, namely, (i) the adsorption, growth and wetting behavior of ILs, (ii) the thermal stability and desorption of ILs, (iii) exchange processes of anions and cations at the IL/solid interface, and (iv) the replacement of ILs from the IL/solid interface by porphyrins.}, author = {Lexow, Matthias and Maier, Florian and Steinrück, Hans-Peter}, doi = {10.1080/23746149.2020.1761266}, faupublication = {yes}, journal = {Advances in Physics: X}, keywords = {growth mode; Ionic Liquids; liquid/solid interface; surface Science; X-ray photoelectron spectroscopy}, month = {Jan}, note = {CRIS-Team Scopus Importer:2020-07-31}, peerreviewed = {Yes}, title = {{Ultrathin} ionic liquid films on metal surfaces: adsorption, growth, stability and exchange phenomena}, volume = {5}, year = {2020} } @article{faucris.313786442, abstract = {Recently, we demonstrated that Pt catalyst complexes dissolved in the ionic liquid (IL) [C4C1Im][PF6] can be deliberately enriched at the IL surface by introducing perfluorinated substituents, which act like buoys dragging the metal complex towards the surface. Herein, we extend our previous angle-resolved X-ray photoelectron spectroscopy (ARXPS) studies at complex concentrations between 30 and 5 %mol down to 1 %mol and present complementary surface tension pendant drop (PD) measurements under ultraclean vacuum conditions. This combination allows for connecting the microscopic information on the IL/gas interface derived from ARXPS with the macroscopic property surface tension. The surface enrichment of the Pt complexes is found to be most pronounced at 1 %mol. It also displays a strong temperature dependence, which was not observed for 5 %mol and above, where the surface is already saturated with the complex. The surface enrichment deduced from ARXPS is also reflected by the pronounced decrease in surface tension with increasing concentration of the catalyst. We furthermore observe by ARXPS and PD a much stronger surface affinity of the buoy-complex as compared to the free ligands in solution. Our results are highly interesting for an optimum design of IL-based catalyst systems with large contact areas to the surrounding reactant/product phase, such as in supported IL phase (SILP) catalysis.}, author = {Hemmeter, Daniel and Paap, Ulrike and Wellnhofer, Nicolas and Gezmis, Emine and Kremitzl, Daniel and Wasserscheid, Peter and Steinrück, Hans-Peter and Maier, Florian}, doi = {10.1002/cphc.202300612}, faupublication = {yes}, journal = {ChemPhysChem}, keywords = {homogeneous catalysis; ionic liquids; surface enrichment; surface tension; X-ray photoelectron spectroscopy (XPS)}, note = {CRIS-Team Scopus Importer:2023-11-10}, peerreviewed = {Yes}, title = {{Understanding} the {Buoy} {Effect} of {Surface}-{Enriched} {Pt} {Complexes} in {Ionic} {Liquids}: {A} {Combined} {ARXPS} and {Pendant} {Drop} {Study}**}, year = {2023} } @article{faucris.120337844, abstract = {The appearance of tetraphenylporphyrins in scanning tunneling micrographs depends strongly on the applied bias voltage. Here, we report the observation and identification of certain features in scanning tunneling microscopy (STM) images of intermixed layers of tetraphenylporphyrin (2HTPP) and cobalt-tetraphenylporphyrin (CoTPP) on Ag(111). A significant fraction of an ordered monolayer of commercially available CoTPP appears as &quot;pits&quot; at negative bias voltages around - 1 V. The obvious possibility that these pits are missing molecules within the ordered layer could be ruled out by imaging the molecules at reduced bias voltages, at which the contrast of the pits fades, and at positive bias voltages around +1 V, at which the image contrast is inverted. With the investigation of the electronic structure, in particular the density of states (DOS) close to the Fermi level, of CoTPP and 2HTPP layers by means of ultraviolet photoelectron spectroscopy (UPS) and scanning tunneling spectroscopy (STS), the contrast mechanism was clarified. The correlation of the bias dependent contrast with the UPS data enabled us to interpret the&quot;pits&quot; as individual 2HTPP molecules. Additional evidence could be provided by imaging layers of different mixtures of 2HTPP and CoTPP and by high-resolution STM imaging of the features in CoTPP. &copy; 2008 American Chemical Society.}, author = {Comanici, Karmen and Buchner, Florian and Flechtner, Ken and Lukasczyk, Thomas and Gottfried, Michael and Steinrück, Hans-Peter and Marbach, Hubertus}, doi = {10.1021/la703263e}, faupublication = {yes}, journal = {Langmuir}, pages = {1897-1901}, peerreviewed = {Yes}, title = {{Understanding} the contrast mechanism in {Scanning} {Tunneling} {Microscopy} ({STM}) images of an intermixed tetraphenylporphyrin layer on {Ag}(111)}, volume = {24}, year = {2008} } @article{faucris.322290136, abstract = {Controlling the local concentration of metal complexes at the surface of ionic liquids (ILs) is a highly sought-after objective due to its pivotal implications in supported ionic liquid phase (SILP) catalysis. Equally important is to avoid per- and polyfluorinated substances due to environmental concerns. Herein, we investigate the surface enrichment of Ru polypyridyl complexes with fluorine-free alkylic side groups of varying lengths and shapes, using the hydrophilic IL [C<inf>2</inf>C<inf>1</inf>Im][OAc] as solvent. Additional charged carboxylate groups are included into the polypyridyl ligands to increase the solubility of the complex in the IL. When the ligand system is functionalized with long and hydrophobic alkyl side chains, the complex predominantly localizes at the IL/vacuum interface, as deduced from angle-resolved X-ray photoelectron spectroscopy. Conversely, in the presence of short or more bulky substituents, no surface enrichment is observed. This buoy-like behaviour with fluorine-free side groups is explored for 0.05 %<inf>mol</inf> to 1 %<inf>mol</inf> solutions. Intriguingly, surface saturation occurs at approximately 0.5 %<inf>mol</inf>, which is beneficial to the efficient operation of catalytic systems featuring high surface areas, such as SILP catalysts.}, author = {Sanchez Merlinsky, Luciano and Hemmeter, Daniel and Baraldo, Luis M. and Maier, Florian and Steinrück, Hans-Peter and Williams, Federico J.}, doi = {10.1002/open.202400092}, faupublication = {yes}, journal = {ChemistryOpen}, note = {CRIS-Team Scopus Importer:2024-05-10}, peerreviewed = {Yes}, title = {{Unlocking} the {Fluorine}-{Free} {Buoy} {Effect}: {Surface}-{Enriched} {Ruthenium} {Polypyridine} {Complexes} in {Ionic} {Liquids}}, year = {2024} } @article{faucris.113095224, abstract = {Ultrahigh vacuum (UHV) surface science techniques are used to study the heterogeneous catalytic dehydrogenation of a liquid organic hydrogen carrier in its liquid state close to the conditions of real catalysis. For this purpose, perhydrocarbazole (PH), otherwise volatile under UHV, is covalently linked as functional group to an imidazolium cation, forming a non-volatile ionic liquid (IL). The catalysed dehydrogenation of the PH unit as a function of temperature is investigated for a Pt foil covered by a macroscopically thick PH-IL film and for Pd particles suspended in the PH-IL film, and for PH-IL on Au as inert support. X-ray photoelectron spectroscopy and thermal desorption spectroscopy allows us to follow in situ the catalysed transition of perhydrocarbazole to carbazole at technical reaction temperatures. The data demonstrate the crucial role of the Pt and Pd catalysts in order to shift the dehydrogenation temperature below the critical temperature of thermal decomposition.}, author = {Matsuda, Takashi and Taccardi, Nicola and Schwegler, Johannes and Wasserscheid, Peter and Steinrück, Hans-Peter and Maier, Florian}, doi = {10.1002/cphc.201500236}, faupublication = {yes}, journal = {ChemPhysChem}, keywords = {heterogeneous catalysis;ionic liquids;liquid organic hydrogen carrier;surface science;x-ray photoelectron spectroscopy}, pages = {1873-1879}, peerreviewed = {Yes}, title = {{Vacuum} {Surface} {Science} {Meets} {Heterogeneous} {Catalysis}: {Dehydrogenation} of a {Liquid} {Organic} {Hydrogen} {Carrier} in the {Liquid} {State}}, volume = {16}, year = {2015} } @article{faucris.120342024, abstract = {A combination of high-resolution X-ray photoelectron spectroscopy at BESSY II and molecular beam techniques has been used to investigate the dissociative adsorption of CH and CD on a Pt(111) surface. From a detailed analysis of C 1s core-level spectra, CH (CD ) has been identified as the adsorbed species at 120 K, independent of the kinetic energy of the impinging methane molecules (in the range from 0.25 to 0.83 eV). The spectra show a unique fine structure, caused by vibrational excitations of C-H (C-D) stretching modes in the photoemission process. Using temperature-programmed XPS, CH is identified as the intermediate in the dehydrogenation process, forming at 260 K and further dehydrogenating to carbon above 500 K. &copy; 2004 Elsevier B.V. All rights reserved.}, author = {Fuhrmann, Thomas and Kinne, Martin and Whelan, Caroline and Zhu, Junfa and Denecke, Reinhard and Steinrück, Hans-Peter}, doi = {10.1016/j.cplett.2004.04.030}, faupublication = {yes}, journal = {Chemical Physics Letters}, pages = {208-213}, peerreviewed = {Yes}, title = {{Vibrationally} resolved in situ {XPS} study of activated adsorption of methane on {Pt}(111)}, volume = {390}, year = {2004} } @article{faucris.120443884, abstract = {Ein Ansatz, Energie chemisch zu speichern, sind fl&uuml;ssige organische Wasserstofftr&auml;ger. Die Oberfl&auml;chenforschung leistet Beitr&auml;ge zum mechanistischen Verst&auml;ndnis der katalytischen Wasserstofffreisetzung und zieht Schlussfolgerungen f&uuml;r die praktische Anwendung solcher Techniken.}, author = {Papp, Christian and Wasserscheid, Peter and Libuda, Jörg and Steinrück, Hans-Peter}, doi = {10.1002/nadc.201490355}, faupublication = {yes}, journal = {Nachrichten aus der Chemie}, pages = {963--969}, peerreviewed = {Yes}, title = {{Wasserstoff}, chemisch gespeichert}, volume = {62}, year = {2014} } @article{faucris.259925648, abstract = {Porphyrins are large organic molecules that are interesting for different applications, such as photovoltaic cells, gas sensors, or in catalysis. For many of these applications, the interactions between adsorbed molecules and surfaces play a crucial role. Studies of porphyrins on surfaces typically fall into one of two groups: (1) evaporation onto well-defined single-crystal surfaces under well-controlled ultrahigh vacuum conditions or (2) more application-oriented wet chemical deposition onto less well-defined high surface area surfaces under ambient conditions. In this study, we will investigate the wet chemical deposition of 5-(monocarboxyphenyl)-10,15,20-triphenylporphyrin (MCTPP) on well-defined rutile TiO<inf>2</inf> (110) single crystals under ambient conditions. Prior to deposition, the TiO<inf>2</inf>(110) crystals were also cleaned wet-chemically under ambient conditions, meaning none of the preparation steps were done in ultrahigh vacuum. However, after each preparation step, the surfaces were characterized in ultrahigh vacuum with X-ray photoelectron spectroscopy (XPS) and the result was compared with porphyrin layers prepared in ultrahigh vacuum (UHV) by evaporation. The differences of both preparations when exposed to zinc ion solutions will also be discussed.}, author = {Wechsler, Daniel and Carolina Fernandez, Cynthia and Köbl, Julia and Augustin, Lisa-Marie and Stumm, Corinna and Jux, Norbert and Steinrück, Hans-Peter and Williams, Federico Jose and Lytken, Ole}, doi = {10.3390/molecules26102871}, faupublication = {yes}, journal = {Molecules}, keywords = {Interfaces; Metalation; Oxide surfaces; Porphyrins; Wet chemical preparation}, note = {CRIS-Team Scopus Importer:2021-06-11}, peerreviewed = {Yes}, title = {{Wet}-chemically prepared porphyrin layers on rutile tio2(110)}, volume = {26}, year = {2021} } @article{faucris.113396184, abstract = {A suitable technology for the preparation of graphene based on versatile wet chemistry is presented for the first time. The protocol allows the wet chemical synthesis of graphene from a new form of graphene oxide that consists of an intact hexagonal \textgreeks-framework of C-atoms. Thus, it can be easily reduced to graphene that is no longer dominated by defects.}, author = {Eigler, Siegfried and Enzelberger-Heim, Michael and Grimm, Stefan and Hofmann, Philipp and Kroener, Wolfgang and Geworski, Andreas and Dotzer, Christoph and Röckert, Michael and Xiao, Jie and Papp, Christian and Lytken, Ole and Steinrück, Hans-Peter and Müller, Paul and Hirsch, Andreas}, doi = {10.1002/adma.201300155}, faupublication = {yes}, journal = {Advanced Materials}, pages = {3583–3587}, peerreviewed = {Yes}, title = {{Wet} {Chemical} {Synthesis} of {Graphene}}, volume = {25}, year = {2013} } @article{faucris.117547364, abstract = {Demetalation of zinc 5,10,15,20-tetraphenylporphyrin (ZnTPP) under acidic conditions and ion exchange with Cu ions at neutral pH are both rapid reactions in the liquid medium. However, for ZnTPP monolayers adsorbed on a Au(111) surface exposed to aqueous solution, we find that, although ion exchange takes place rapidly as expected, demetalation does not occur, even at pH values as low as 0. Based on this, we conclude that metal center exchange on the surface does not proceed through a free-base porphyrin as an intermediate. Furthermore, once formed, CuTPP is stable on the surface and the reverse exchange from CuTPP to ZnTPP in the presence of Zn ions could not be achieved. The preference for copper is so strong that even an attempt to exchange adsorbed ZnTPP with Ni ions in the presence of traces of Cu yielded CuTPP rather than NiTPP.}, author = {Franke, Matthias and Marchini, Florencia and Jux, Norbert and Steinrück, Hans-Peter and Lytken, Ole and Williams, Federico J.}, doi = {10.1002/chem.201600634}, faupublication = {yes}, journal = {Chemistry - A European Journal}, keywords = {Ion exchange; Metalation; Porphyrins; Solid-liquid interfaces; Zinc}, pages = {8520-8524}, peerreviewed = {Yes}, title = {{Zinc} {Porphyrin} {Metal}-{Center} {Exchange} at the {Solid}-{Liquid} {Interface}}, volume = {22}, year = {2016} }