Large enhancement in dissociative electron attachment to HCl adsorbed on H2O ice via transfer of presolvated electrons

We report that dissociative electron attachment (DEA) to HCl is strongly enhanced by adsorption on the surface of H2O ice. The absolute DEA cross section at similar to0 eV for HCl adsorbed on ice is measured to be similar to4.0x10(-15) cm(2), which is two orders of magnitude higher than in the gas phase. This enhancement is essentially due to electron transfer from precursor states of the solvated electron in ice to an unfilled molecular orbital of HCl followed by its dissociation. This study indicates that electron-induced dissociation may be a significant process leading to HCl dissociation on ice surfaces in polar stratospheric clouds due to ionization by cosmic rays. (C) 2001 American Institute of Physics.