THE VEGARD-KAPLAN BAND AND THE PHOSPHORESCENT DECAY OF N-2

The phosphorescence transition A (3) Sigma(u)(+) --> (1) Sigma(g)(+) i n N-2 is studied by quadratic response and multi-configuration self-co nsistent field theory. Using full valence correlation reference wavefu nctions, response theory predicts the total radiative lifetime of the (upsilon'=0) A (3) Sigma(u,1)(+), state (the Sigma=1 component) to 2.5 8 s and the corresponding averaged radiative lifetime to 3.87 s, to be compared with the experimental averaged value of 1.9 s. Though there is a systematic overestimation of the lifetime, the theoretical phosph orescence transition moment curve and the relative vibronic intensitie s are in good agreement with experiment. A novel derivation of the rel ation between an induced transition moment and a residue of the quadra tic response function is presented.