LAUSR

Abstract Data available on the 5d 3 , 5d 2 6s and 5d 2 6p configurations in the Lu I isoelectronic sequence have been critically reviewed by means of calculations with the orthogonal operators. The study included spectra from Ta III through Hg X. The calculations agree very well with the experimental data. The isoelectronic behavior of parameters and deviations of the experimental levels from the calculated positions, Δ E = ( E exp − E calc ), show regular trends. Three missing 5d 2 6s levels have been accurately predicted theoretically and confirmed experimentally: the level ( 3 P) 2 P 3∕2 in Pt VIII and the levels ( 3 P) 4 P 5∕2 and ( 3 P) 2 P 1∕2 in Os VI have been determined in the study. The research suggested revision of the published initial analyses of the Re V and Hg X spectra. The recently completed revised analysis of Re V has confirmed the issues noticed in the initial analysis and has resulted in the data that fit very well in the current parametric study. The isoelectronic evolution of the higher order interactions was studied for the first time in the Lu I sequence. The study included the parameters A c , A 3 – A 6 describing two-particle magnetic interaction of the dd-type, the parameter A mso describing two-particle magnetic ds-type effect, the parameter T dds describing 3-particle electrostatic ds-type interaction, and the effective parameters S 1 and S 2 of the dp-type.