Morphology effects in anion electron-stimulated desorption

Electron-stimulated desorption of O- anions from O-2-covered multilayer condensed films of various molecules is investigated in the energy range 0-20 eV. A suppression of O- signal below 1 eV is observed from <0.1 monolayer (ML) of O-2 deposited on either 4 ML of D2O or 6 ML NH3 condensed at 15 K. A detailed study of O-2/D2O target shows that the magnitude of the O- signal depends strongly on temperature (15-150 K) of D2O condensation on Pt, on the amount of condensed O-2 (0.1-4 ML) and on the D2O film thickness (4-100 ML). These results are shown to be related to different morphologies of the ice layer. (C) 2000 Elsevier Science B.V. All rights reserved.