title: Dissociative electron attachment resonances in ammonia: a velocity slice imaging based study.
abstract: Negative ion resonance states of ammonia are accessed upon capture of electrons with energy 5.5 eV and 10.5 eV, respectively. These resonance states dissociate to produce H(-) and NH(2)(-) fragment anions via different fragmentation channels. Using the velocity slice imaging technique, we measured the angular and kinetic energy distribution of the fragment H(-) and NH(2)(-) anions with full 0-2π angular coverage across the two resonances. The scattered H(-) ions at both resonances show variation in their angular distribution as a function of the kinetic energy indicating geometric rearrangement of NH(3)(-*) ion due to internal excitations and differ from the equilibrium geometry of the neutral molecule. The second resonance at 10.5 eV shows strong forward-backward asymmetry in the scattering of H(-) and NH(2)(-) fragment ions. Based on the angular distributions of the H(-) ions, the symmetry of the resonances at 5.5 eV and 10 .5 eV are determined to be A(1) and E, respectively, within C(3v) geometry.
authors.affiliation: LaserLab and Physical Chemistry, Vrije Universiteit, Amsterdam 1081 HV, The Netherlands. nbhargavram@gmail.com
authors.forename: N
authors.initials: N
authors.lastname: Bhargava Ram
authors.forename: E
authors.initials: E
authors.lastname: Krishnakumar
mesh_terms: D000641:Ammonia / Q000737:chemistry*; D004583:Electrons; D007700:Kinetics
chemical_list: D000641:Ammonia