Electron-impact excitation of Na

Total and resonance electron-impact cross sections are obtained for Na in six-state (6CC) and four-state close-coupling (4CC) approximations for the electron energy range 3.5≤E≤150 eV. Accurate configuration-interaction target wave functions are employed to represent the ground state 3 ${}_{}{}^2{}_{}{}^{}S$ and the excited states $3^2$P°, 3 ${}_{}{}^2{}_{}{}^{}D$,$4^2$S, 4 ${}_{}{}^2{}_{}{}^{}°$, and 4 ${}_{}{}^2{}_{}{}^{}D$. The 4CC results are in excellent agreement with calculated and measured total cross sections for E≤5 eV. Above 10 eV our 6CC resonance cross sections are in accord with measurement, and disagreements among experimental measurements of total cross sections are resolved. We also find that the cross section σ(3s→4d) is much larger than hitherto anticipated. The mechanism responsible is suggested.