Sputtering of Ordered Ice Ih Adsorbed on Rh(111) Using Hyperthermal Neutral Ar Atoms

Abstract

The sputtering of ordered overlayers of water physisorbed on Rh(111) by hyperthermal Ar atoms was investigated. For incident kinetic energies of 10 to 20 eV, the impact of the Ar atoms leads to the desorption of intact single water molecules. This sputtering is sensitive to the crystalline structure of the ice overlayers with the intensity and energy of the sputtered molecules being dependent upon both the final polar and azimuthal angles. The similarity between the results for one and three layers of water strongly suggests that all of the sputtering originates from the exposed topmost layer. In all cases sputtering yields are small, ∼10−3, and decreases with increasing film thickness; most of the energy transferred during the collision is dissipated into the lattice. These results suggest that sputtering of surfaces with hyperthermal neutrals might be useful as a noncharging and nonchemically destructive adjunct to ion-induced sputtering and secondary ion mass spectroscopy for compositional depth profiling and trace analysis. Intact neutral molecules are ejected, and the molecules left on the surface have not been altered, which is not the case for ion sputtering.