Doppler-free kinetic energy release spectrum of NO2+ and ab initio CI calculations

The nitric oxide dication, NO2+, is studied using Doppler-free kinetic energy release spectroscopy and ab initio CI calculations. The C 2Σ+ and 2 4Π states have been observed and studied at vibrational resolution. The B 2Σ+ state has also been investigated. The ν = 0 level of the C 2Σ+ state dissociates by tunnelling through a potential barrier into N+ (3P) + O+(2D). Spin-orbit interaction with a repulsive 6Σ+ state accounts for the dissociation of the ν = 0 level in the 2 4Π state into the ground state ion pair N+ (3P) + O+ (2P)). Predissociation into N+(3P) + O+(4S) due to (N+ (3P) + O+(2D) and N+(3P) + O+(2P)). Predissociation into N+(3P) + O+(4S) due to spin-orbit coupling with the 1 4Π state governs the dissociation of the first three vibrational levels in the B 2Σ+ state. The apparent relative population of the vibrational levels in this state is strongly influenced by radiative transitions to the X 2Σ+ state.