An Extension of the Thallium II Spectrum

Abstract

The spectrum of thallium from the hollow cathode discharge in He has been photographed in the region from 9250A to 600A. The classification of the first spark spectrum has been approximately doubled by the assignment of 160 new lines, which locate 35 new levels. These include members up to $n=11 \mathrm{and} 12$ of the $s$, $p$, and $d$ series (which establish the ionization potential as 164,765\ifmmode\pm\else\textpm\fi{}5 ${\mathrm{cm}}^{\ensuremath{-}1}$), the first two members of the $g$ series, and six levels of the $5{d}^{9}6{s}^{2}6p$ configuration. Perturbations are present in many of the series, due to their interaction with the $6{p}^{2}$ and $5{d}^{9}6{s}^{2}6p$ configurations. The $6s6g$ term appears to have hyperfine structure larger than its multiplet structure. Practically all of the hollow cathode lines of thallium in the entire spectrum have now been classified.