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A Critical Compilation of Experimental Data on Spectral Lines and Energy Levels of Hydrogen, Deuterium, and Tritium



Alexander Kramida


For more than 50 years, Charlotte Moore's Atomic Energy Levels compilation and its subsequent revisions have been the standard source of reference data for the spectra of hydrogen and its isotopes. In these compilations, theoretical data based on quantum-electrodynamic (QED) calculations have been given. This reflects the fact that the theory of the hydrogen spectrum has been perfected to an extent far exceeding the capabilities of the best experimental measurements. However, rapid advances in the techniques of laser spectroscopy have recently brought the experiment on a par with theory in terms of precision of acquired data. This calls for replacement of the commonly used reference data sets with the new data based entirely on experimental observations. The present work compiles several tens of recent measurements of the hydrogen, deuterium, and tritium fine and hyperfine structure intervals and presents sets of energy levels and Ritz wavelengths derived from these measurements. Fine-structure data exist for up to principal quantum number n = 12 in hydrogen and deuterium. Above that, there are many observed lines with unresolved fine structure. From these observations, level centers (centers of the fine structure) are derived by a least-squares optimization, and Ritz wavelengths of series with upper levels up to n = 40 are obtained. For tritium, the n = 2 and 3 energy level intervals are derived from experimental observations.
Atomic Data and Nuclear Data Tables


Energy levels, Wavelengths, Hyperfine Structure, Isotope Shift, Ionization potential, Hydrogen atom, Tritium, Deuterium, Critical Compilation


Kramida, A. (2010), A Critical Compilation of Experimental Data on Spectral Lines and Energy Levels of Hydrogen, Deuterium, and Tritium, Atomic Data and Nuclear Data Tables, [online],, (Accessed May 26, 2024)


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Created June 1, 2010, Updated April 7, 2024