Observation of Negative Ion Resonances in Amorphous Ice via Low-Energy (5–40 eV) Electron-Stimulated Production of Molecular Hydrogen

Greg A. Kimmel; Thomas M. Orlando

doi:10.1103/PhysRevLett.77.3983

Observation of Negative Ion Resonances in Amorphous Ice via Low-Energy (5–40 eV) Electron-Stimulated Production of Molecular Hydrogen

Greg A. Kimmel and Thomas M. Orlando

Phys. Rev. Lett. 77, 3983 – Published 4 November 1996

Abstract

The $D_{2} ({}^{1}Σ_{g}^{+}$ , $v = 0 - 2$ , $J = 0 - 2$ ) desorbates produced during low-energy (5–40 eV) electron-beam irradiation of amorphous $D_{2}$ O ice were monitored using resonance-enhanced laser ionization spectroscopy. We attribute the structure in the $D_{2}$ yield as a function of the incident electron energy to core-excited negative ion resonances. These resonances, or the excited states produced after electron autodetachment, decay via molecular elimination to yield $D_{2} ({}^{1}Σ_{g}^{+})$ directly. $D_{2}$ is observed with $v = 0$ or 2 but not $v = 1$ , suggesting a symmetry propensity in the excitation or decay of the resonances.