Electron stimulated desorption via dissociative attachment in amorphous H2O

Low energy (0–12 eV) electron impact on condensed amorphous H2O and D2O films is shown to induce electron stimulated desorption of H− and D−, respectively, via dissociative electron attachment. The onsets for H− and D− detection are at 5.5 eV, with a maximum yield for anion desorption at ∼7.4 eV. The kinetic energy distributions of the desorbing anions are peaked near 0 eV, indicating that the anions suffer post-dissociation collisions at or near the surface, with a large probability of anion trapping on the surface. The present results provide direct information on the dissociation products, prior to the interferences of subsequent reaction processes in the condensed film.