Analysis of the 5$p^6$→5$p^5$nl (J=1) Rydberg series in ${\mathrm{Ba}}^{2+}$

A detailed analysis is made for the bound 5$p^6$→5$p^5$ns,nd levels observed in the photoabsorption of ${\mathrm{Ba}}^{2+}$. A multichannel quantum-defect theory approach, with ab initio calculations for some of the parameters, is used to describe periodic enhancements in intensity associated with interchannel mixing. Qualitative agreement between experiment and theory requires the inclusion of plasma-broadening effects to account for the apparent increase in strength of the higher n levels.