Observation of negative ion resonances in amorphous ice via low-energy (5-40 eV) electron-stimulated production of molecular hydrogen

The D-2((1) Sigma(g)(+), v = 0-2, J = 0-2) desorbates produced low-energy (5-40 eV) electron-beam irradiation of amorphous (DO)-O-2 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) Sigma(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.