ELECTRONIC SPUTTERING OF OXYGEN AND WATER-MOLECULES FROM THIN-FILMS OF WATER ICE BOMBARDED BY MEV NE+ IONS

Thin films of water ice are both chemically altered and physically eroded when bombarded with energetic ions. Water molecules are destroyed and new molecules (H2 and O2 for example) are formed. The new species may diffuse in the ice and escape from the surface by sublimation or be eroded along with water molecules that are sputtered from the surface. To evaluate the relative importance of production, diffusion and erosion we have examined with quadrupole mass spectrometry H2O and O2 emitted from ice films of different thickness under bombardment by 1.5 MeV Ne ions at 7 K. The primary and secondary species are very clearly separated in their behavior. © 1990.