Energy Technology Data Exchange (ETDEWEB)

In this systematic examination of some of the spectroscopic properties of the f-elements we deal with both the trivalent lanthanides and actinides. We summarize the present status of our energy level calculations in single crystal matrices and in aqueous solution, and compare the predicted crystal-field structure in certain low-symmetry sites with that observed. Some interesting new structural insights are thereby gained. The state eigenvectors from these calculations are then used in part in reassessing and interpreting the intensities of transitions in aqueous solution via the Judd-Ofelt theory. The parameters of this theory derived from fitting experimental data are compared with those computed from model considerations. Finally, we discuss some recent contributions to the interpretation of excited state relaxation processes in aqueous solution. 79 references, 23 figures, 17 tables.

International Nuclear Information System (INIS)

The absorption and magnetic circular dichroism spectra of [N(n-Bu)_4]"+[(MeCp)_3PrCl]"- dissolved in 2-MeTHF were measured at room and at low temperatures. On the basis of these spectra the crystal field splitting pattern could be derived. The parameters of an empirical Hamiltonian were fitted to the energies of 42 levels to give an r.m.s. deviation of 23 cm"-"1. From the crystal field parameters obtained the crystal field strength of the ligand collective was estimated. Compared with neutral Cp_3Pr circle B complexes the crystal field strength of the anionic [(MeCp)_3PrCl]"- moiety is unusually low. (orig.)

Energy Technology Data Exchange (ETDEWEB)

The one-particle models of crystal-field theory provide a qualitative interpretation for the observed ground state splitting of four Kramers doublets of the {sup 8}S{sub 7/2} of Bk{sup 4+} doped into CeF{sub 4}. A set of nine nonzero (B{sup k}{sub q}) parameters corresponding a C{sub 2v} point symmetry provide a very good correlation between the experimental data and simulated energy level schemes within a rms deviation of 13.7 cm{sup -1}. The calculated and experimental energy values have the same order-of-magnitude for the ground state and excited components. The total ground state splitting of the S-state ions of f-elements such as Bk{sup 4+} in CeF{sub 4} is larger when compared with Cm{sup 3+} :LaCl{sub 3} and Gd{sup 3+} :La(C{sub 2}H{sub 5}SO{sub 4}){sub 3}-9H{sub 2}O ions. The so-called crystal-field strength parameter, N{sub v}, increases as a function of the increasing maximum splitting of the ground state due to a decrease in the participation of the pure ...