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In addition, there are two publications containing equations and the underpinning theory for molecular spectroscopy.</p><p><a href="https://web.archive.org/web/20240720220726/https://www.nist.gov/pml/atomic-and-molecular-data"><strong>Atomic and Molecular Data</strong></a></p><p>Contains databases on thermophysical properties of gases, electron-impact cross sections (of atoms & molecules), potential energy surfaces of group II dimers, and atomic weights and isotopic compositions.</p><p><a href="https://web.archive.org/web/20240720220726/https://www.nist.gov/pml/x-ray-and-gamma-ray-data"><strong>X-Ray and Gamma-Ray Data</strong></a></p><p>Contains databases on the interaction of x-rays and gamma-rays with elements and compounds.</p><p><a href="https://web.archive.org/web/20240720220726/https://www.nist.gov/pml/radiation-dosimetry-data"><strong>Radiation Dosimetry Data</strong></a></p><p>This database calculates stopping-power and range tables for electrons, protons, or helium ions.</p><p><a href="https://web.archive.org/web/20240720220726/https://www.nist.gov/pml/nuclear-physics-data"><strong>Nuclear Physics Data</strong></a></p><p>Contains a database of the isotopic compositions, atomic weights and relative atomic masses of the elements.</p><p><a href="https://web.archive.org/web/20240720220726/https://www.nist.gov/pml/condensed-matter-physics-data"><strong>Condensed Matter Physics Data</strong></a></p><p>This database consists of evaluated data for use in total-energy calculations of electronic structure by density-functional theory. It contains total energies and orbital energy eigenvalues for all atoms from hydrogen to uranium.</p><p><a href="https://web.archive.org/web/20240720220726/https://www.nist.gov/srd"><strong>Other NIST Data</strong></a></p><p>Provides access to all data sets at NIST.</p><hr><p>The use of International Units and the expression of uncertainty in measurement is critical to all data activities. 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