New Energy Levels in Au II, Hg III, Tl IV, Pb V and Bi VI

Abstract

All the previously unknown $5{d}^{10}$, $5{d}^{9}6s$ and $5{d}^{9}6p$ levels in all the stable members of the platinum-like isoelectronic sequence, and some $5{d}^{9}6d$ and $5{d}^{9}7s$ levels, have been identified. Several corrections are made to the literature on Au II, Hg III and Tl IV. The Pb V and Bi VI classifications verify Arvidsson's estimates of the stages of ionization for the individual lines. The $5{d}^{9}6p{|}_{0}$ levels were found only in consequence of Goble's predictions from his solution of the four-vector problem. The dependence of the energy and intensity values upon the atomic number is very smooth, except for a branching effect explained by Goble. New ${d}^{9}s$ screening numbers and Houston parameters are given. Ionization potentials are estimated, by a comparison method, up to 87.9\ifmmode\pm\else\textpm\fi{}0.7 volts for Bi VI. Analysis of the one (partly resolved) hyperfine structure pattern attributed to Bi VI yields a splitting factor $a(6s)=3.1\ifmmode\pm\else\textpm\fi{}0.2$ ${\mathrm{cm}}^{\ensuremath{-}1}$.