Theoretical study of the first and second negative systems of N+2

The potential curves for the X 2Σ+g, B 2Σ+u, C 2Σ+u, (1) 2Δu, (2) 2Δu, 4Πu, and 2Σ−u states of N+2 are determined using extended Gaussian basis sets and large CASSCF/multireference CI wave functions. The radial dependence of the electronic transition moments for the first and second negative systems of N+2 are determined, and used to compute Einstein coefficients and radiative lifetimes. Based on the calculated crossing points between the C 2Σ+u , 4Πu, and 2Σ−u states, the predissociation in the C 2Σ+u state for v′≥3 appears to first involve a spin–orbit induced crossing to the bound 2Σ−u state, followed by predissociation of this state by the 4Πu state, which crosses it on the outer limb (just above v′=3 of the C state). This is consistent with the accidental predissociation mechanism suggested by Lorquet and Lorquet.