Velocity-map imaging study of the O(3P)+N2 product channel following 193 nm photolysis of N2O

Abstract

Velocity-map imaging has been used to characterize the velocity and angular momentum alignment distributions of the O(3PJ) products of N2O photolysis at 193 nm. The measured velocity and spatial anisotropy distributions indicate that around 60% of the available energy appears in product translation, with the remainder being released into internal excitation of the N2 cofragment. The measured O(3PJ) alignment parameters have been interpreted in terms of an instantaneous dissociation model, which suggests preferential population of ML=0 states and an electron density distribution peaking perpendicular to the direction of the breaking bond. This is consistent with dissociation on a surface of Σ− symmetry, the most likely candidate correlating with ground state products being the asymptotic Σ1 −Σ−(3A″) surface. There are several possible routes to this surface, and these are considered in light of the measured velocity distributions and velocity-dependent spatial anisotropy parameters of the O(3P) products relative to the dominant O(1D) dissociation channel.