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

Two-dimensional multistate potential energy surfaces along N-NO bond length and N-N-O bond angle of N2O+ in the A2 sigma+ and B2 pi 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 ge-ometry for the A2A'(A2 sigma+) state with a lower barrier, leading to rotationally excited NO+(X1 sigma+) and N(2D) fragments. Likewise, the respective contributions of the A' and A '' components split from the B2 pi 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.

Automated summary

In this study, two-dimensional potential energy surfaces along the N-NO bond length and N-N-O bond angle of N2O+ in the A2 sigma+ and B2 pi states were calculated using CASPT2/cc-pVQZ level. A new N-NO bond fission pathway was proposed in the bent geometry of the A2A'(A2 sigma+) state, which has a lower barrier compared to the known decomposition mechanisms in linear structure. Additionally, the contributions of the A' and A'' components split from the B2 pi state were clarified, and the effect of avoided crossing and spin state coupling on the ro-vibrational distributions of the NO+ fragment ion observed in experiments were explained.