Absolute term values for the quartet states of neutral lithium

Abstract

An extensive configuration-interaction calculation for the $\mathrm{}\left(1s2s3s\right)\mathrm{}$ ${}_{}{}^4{}_{}{}^{}S$ state of neutral lithium has been carried out in an effort to establish absolute term values for the low-lying quartet states with a few ${\mathrm{cm}}^{-1\mathrm{}}$ of accuracy. The lowest quartet state, $\mathrm{}\left(1s2s2p\right)\mathrm{} {}_{}{}^4{}_{}{}^{}P_{}^o{}_{}{}^{}$ is found to be 57.4128 (10) eV above the ground state $1s^{2}2s$, in apparent disagreement with a recent experimental value of 57.4420 (40) eV obtained from Ritz formulas applied to the ${}_{}{}^4{}_{}{}^{}D$ states of even and odd parity. The positions of all identified quartets have been recalculated from raw experimental data and new theoretical results.