[en] A resume is given of the experimental data on energy levels of isolated actinide neutral atoms and ions derived from analysis of the spectra of the vapour phase at low density. Typically, a neutral actinide has a thousand experimental levels and the ionized state somewhat fewer. Most levels can be identified only by comparison with theoretical calculations using appropriate parameters. The theoretical description of the term structure is outlined and the fitting of parameters discussed. The lowest level of all known actinide electron configurations is listed together with isotope shifts and hyperfine structure widths. Some interpretation of the data in terms of general trends and the implications for actinide chemistry is attempted. (author)

[en] The atomic spectroscopic data available for plutonium are among the rickest of any in the periodic system. They include high-resolution grating and Fourier-transform spectra as well as extensive Zeeman and isotope-shift studies. We summarize the present status of the term analysis and cite the configurations that have been identified. A least-squares adjustment of a parametric Hamiltonian for configurations of both Pu I and Pu II has shown that almost all of the expected low levels are now known. The use of a model Hamiltonian applicable to both lanthanide and actinide atomic species has been applied to the low configurations of Pu I and Pu II making use of trends predicted by ab initio calculations. This same model has been used to describe the energy levels of Pu³⁺ in LaCl₃, and an extension has permitted preliminary calculations of the spectra of other valence states

[en] The atomic spectroscopic data available for plutonium are among the richest of any in the periodic system. They include high-resolution grating and Fourier-transform spectra as well as extensive Zeeman and isotope-shift studies. The present status of the term analysis is summarized, and the configurations that have been identified are cited. A least-squares adjustment of a parametric Hamiltonian for configurations of both Pu I and Pu II has shown that almost all of the expected low levels are now known. The use of a model Hamiltonian applicable to both lanthanide and actinide atomic species has been applied to the low configurations of Pu I and Pu II making use of trends predicted by ab initio calculations. This same model has been used to describe the energy levels of Pu³⁺ in LaCl₃, and an extension has permitted preliminary calculations of the spectra of other valence states. 46 references, 9 figures, 7 tables