Dissociation dynamics in low energy electron attachment to ammonia using velocity slice imaging

Abstract

The complete dissociation dynamics of low energy electron attachment to the ammonia molecule has been studied using velocity slice imaging (VSI) spectrometry. One low energy resonant peak around 5.5 eV and a broad resonance around 10.5 eV incident electron energies have been observed. The resonant states mainly dissociate via H⁻ and NH₂⁻ fragments, though for the upper resonant state, the signature of NH⁻ fragments is also predicted due to a three-body dissociation process. Kinetic energy and angular distributions of the NH₂⁻ fragment anions are measured simultaneously around the two resonances. Based on our experimental observations, we conclude that a temporary negative ion (TNI) state with A₁ symmetry is responsible for the lower resonance. Whereas, we find strong evidence for the existence of a TNI state having A₁ symmetry at the 10.5 eV resonance for the first time.