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Update of Atomic Data for the First Three Spectra of Actinium



Alexander Kramida


Abstract: The present article describes a complete re-analysis of all published data on observed spectral lines and energy levels of the first three spectra of actinium (Ac I–III). In Ac I, three previously determined energy levels have been rejected, 12 new energy levels have been found; for six previously known levels, either the J values or the energies have been revised, and the ionization energy has been re-determined with an improved accuracy. In the line list of Ac I, three previous classifications have been discarded, 16 new ones have been found, and three have been revised. In Ac II, 16 new energy levels have been established, and 36 new identifications have been found for previously observed but unclassified lines. In both Ac I and Ac II, new sets of transition probabilities have been calculated. For all three spectra, complete data sets of critically evaluated energy levels, observed lines, and transition probabilities have been constructed to serve as recommended data on these spectra.


atomic databases, standard reference databases, atomic spectroscopy, actinides, actinium, spectral lines, energy levels, transition probabilities


Kramida, A. (2022), Update of Atomic Data for the First Three Spectra of Actinium, Atoms, [online],, (Accessed April 16, 2024)
Created April 22, 2022, Updated July 3, 2023