1S1,2S1, and2S3States ofLi+

Abstract

The ionization energy $J$, excluding the Lamb shift, of the ground state of ${\mathrm{Li}}^{+}$ has been evaluated for determinants up to order $n=444\mathrm{}$. We get $J\left(444\right)=610087.449\mathrm{}$ ${\mathrm{cm}}^{-1\mathrm{}}$, and an extrapolated value $J\left(\infty \right)=610087.445\mathrm{}$ ${\mathrm{cm}}^{-1\mathrm{}}$. For the $2{}_{}{}^1{}_{}{}^{}S$ state we get a theoretical ionization energy of 118704.88 ${\mathrm{cm}}^{-1\mathrm{}}$, as against the experimental value of 120008.30±0.10 ${\mathrm{cm}}^{-1\mathrm{}}$ determined by Herzberg and Moore. It appears that the 8517.4 A line first measured by Series and Willis and later by Herzberg and Moore has been incorrectly identified as the $2{}_{}{}^1{}_{}{}^{}S-2\mathrm{}{}_{}{}^1{}_{}{}^{}P$ transition. It should be looked for at 9584 A. For the $2{}_{}{}^3{}_{}{}^{}S$ state our value for the ionization energy comes out 134044.12 ${\mathrm{cm}}^{-1\mathrm{}}$, in excellent agreement with the experimental value of 134044.19±0.10 ${\mathrm{cm}}^{-1\mathrm{}}$ determined by Herzberg and Moore.