THE 3-PI-G[-3-SIGMA-U+ TRANSITION IN N22+

As part of a theoretical reexamination of the electronic states of N2(2+), we have used multireference configuration interaction wave functions with CASSCF reference states and a [5s,4p,3d,2f,1g] generally contracted Gaussian basis to calculate ab initio potential curves of the excited 3-SIGMA-u+ and 3-PI-g electronic states. The calculated energy difference and spectroscopic constants support the assignment of the N2(2+) spectral lines observed near 15 300 cm-1 as the upsilon' = 0 <-- upsilon" = 0 band of the 3-PI-g <-- 3-SIGMA-u+ transition. The upsilon' = 0 <-- upsilon" = 1 band is predicted to lie at 13 146 cm-1 and the upsilon' = 1 <-- upsilon" = 0 band at 16 246 cm-1. The latter transition may be the broad, unassigned feature observed by Cosby and co-workers near that energy.