Configuration Interaction in the Pb III Spectrum

Abstract

The Slater and the configuration perturbation parameters were evaluated for configurations of Pb III by fitting the calculated to the observed term values. The wave functions of 52 levels were determined in terms of the ($\mathrm{LS}$) functions, and for many of the levels were found to be linear combinations of the ($\mathrm{LS}$) functions of two or more configurations. The $g$-values, hyperfine structure interval factors, and isotope shifts evaluated from the precise wave functions are in excellent agreement with the observed values. Thus the theory gives an internally consistent explanation of the spectroscopic properties. Since the isotope shifts were calculated as a field effect the agreement shows that the specific mass effect is relatively unimportant for heavy elements. The values of the shift and hyperfine structure interaction constant for the $6s$ electron obtained from this analysis are 0.50 ${\mathrm{cm}}^{\ensuremath{-}1}$ and 2.60 ${\mathrm{cm}}^{\ensuremath{-}1}$, respectively.