Theoretical re-investigation on the N–N bond breaking of N2O+ cations in the A2Σ+ and B2Π states at the CASPT2 level

Abstract

Two-dimensional multistate potential energy surfaces along N–NO bond length and N–N–O bond angle of N2O+ in the A2Σ+ and B2Π states were calculated at the CASPT2/cc-pVQZ level. In comparison to the known decomposition mechanisms in linear structure, a new N–NO bond fission pathway was proposed in bent geometry for the A2Aʹ(A2Σ+) state with a lower barrier, leading to rotationally excited NO+(X1Σ+) and N(2D) fragments. Likewise, the respective contributions of the Aʹ and A″ components split from the B2Π state were clarified. Considering avoided crossing and the coupling of spin states, ro-vibrational distributions of the NO+ fragment ion observed in experiments are elucidated.