The Dissociative Electroionization of Ammonia and Ammonia-d3. II. The H+ and H2+ Dissociation Channels.

The dissociative electroionization of NH3(ND3) in the H(D)+ and H(D)2+ dissociation channels is investigated in the 18-50 eV electron energy range. The H(D)+ translational energy distribution spectrum shows several components and that of H(D)2+ is continuous. The thermal energy component of the latter distribution is entirely ascribed to H2+/H2. For both ions the kinetic energy-versus-appearance energy diagram is obtained and discussed. The H+ ion at the lowest onset is probably formed at the expense of the NH3+(A2E) state. In the 22.5 eV electron energy range both H+ and H2+ are formed by dissociative autoionization. Evidence is also brought for H+ and H2+ formation at 22.5 eV and 26.5 eV through spontaneous decomposition of NH2+. Above 35 eV dissociation of doubly ionized states by Coulomb repulsion is mainly involved.