Low Even Configurations in the First Spectrum of Rhenium (Re i)

Abstract

The theory of intermediate coupling with configuration interaction is used to calculate energy levels and $g$ values in the $5{d}^{5}6{s}^{2}$ and $5{d}^{6}6s$ configurations of Re i. Fifty-one observed levels are fitted with a mean deviation of \ifmmode\pm\else\textpm\fi{}325 ${\mathrm{cm}}^{\ensuremath{-}1}$ by using eleven free parameters. The $L(L+1)$ correction is important, as the mean deviation is \ifmmode\pm\else\textpm\fi{}514 ${\mathrm{cm}}^{\ensuremath{-}1}$ without it; the parameter for this correction ($\ensuremath{\alpha}=66.8\ifmmode\pm\else\textpm\fi{}13$) has a value similar to that in first and second long-period spectra. Standard deviations of the parameters are calculated, and within the limits so defined, Slater's parameters are consistent with expectations based on known behavior in first and second long-period spectra. Calculated $g$ values agree with observed values for thirty-seven levels to about \ifmmode\pm\else\textpm\fi{}0.03. Levels not previously assigned from experiment are given designations; the eigenvectors are used to illustrate qualitative features of these designations.