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-2 Sigma(+) and 2 (II)-I-4 states have been observed and studied at vibrational resolution. The B (2) Sigma(+) state has also been investigated. The upsilon = 0 level of the C (2) Sigma(+) State dissociates by tunnelling through a potential barrier into N+(P-3) + O+(D-2). Spin-orbit interaction with a repulsive (6) Sigma(+) state accounts for the dissociation of the upsilon = 0 level in the 2 (II)-I-4 State into the ground state ion pair N+(P-3)+ O+(S-4). There is evidence for two other dissociation channels (N+(P-3) + O+(D-2) and N+(P-3) + O+(P-2)). Predissociation into N+(P-3) + O+(S-4) due to spin-orbit coupling with the 1 (II)-I-4 State governs the dissociation of the first three vibrational levels in the B (2) Sigma(+) state. The apparent relative population of the vibrational levels in this state is strongly influenced by radiative transitions to the X (2) Sigma(+) State.