The Spectra of Rb III and Sr IV

By applying Shortley's equations to the $4s^{2}4p^5\left({}_{}{}^2{}_{}{}^{}P_{}^0{}_{}{}^{}\right)5p$ levels of Rb II, the separation of the ground levels $4s^{2}4p^5{}_{}{}^2{}_{}{}^{}P_{}^0{}_{}{}^{}$ of Rb III has been computed, and experimentally observed to be 7380 ${\mathrm{cm}}^{-1\mathrm{}}$. In the case of Sr IV, the ${}_{}{}^2{}_{}{}^{}P_{}^0{}_{}{}^{}$ separation has been predicted from the regular doublet law and identified from the data as 9731 ${\mathrm{cm}}^{-1\mathrm{}}$. On the basis of transitions into the ground doublet certain $4s^{2}4p^{4}4d$ and $4s^{2}4p^{4}5s$ levels have been located.