Dissociative electron attachment to NO probed by velocity map imaging

Abstract

An experimental and theoretical investigation of the dissociative electron attachment process in nitric oxide is presented. Measurements using the recently developed ion momentum imaging conclusively show the presence of two resonance features in the O⁻ channel. These are found to dissociate to give N atoms in the ²D and ²P excited states respectively, thus settling the controversies regarding the possible dissociation limits of this process. Though the angular distribution of O⁻ shows the resonances contributing to these dissociations are of Π symmetry and a mixture of Π and Σ or Δ symmetry respectively, our calculations using R-matrix theory show no direct electron attachment channel leading to O⁻ through these resonances, as all the allowed resonances below 10 eV decay to either O + N⁻ or O⁻ + N(⁴S) channels. We propose that indirect mechanisms through curve crossings lead to the experimentally observed results.