Enhanced erosion of frozen H2O films by high energy 19F ions

We have measured sputtering yields of H2O films with 19F ions at bombarding energies from 1.6 to 25 MeV. The sputtering yield was found to be very sensitive to the incident charge state of the beam, and insensitive to the thickness of the ice film for thicknesses ranging from approximately 20 to 80 x 1016 H2O/cm2. The yield was independent of the target substrate temperature from 10 to 60 K and independent of the F beam current density from < 1 to approximately 5.5 particle nanoamps/mm2. There are several models proposed to explain enhanced sputtering of dielectrics; we have discussed their relevance to our data. (author)