Sputtering of water ice by keV electrons at 60 K

Abstract

We have measured the sputtering yield of H2O–ice for 0.5–10 keV electrons at 60 K using microbalance gravimetry. We find that over the energy range studied Y (H2O) changes by a factor of ∼16, indicating that there is a clear relation between Y (H2O) and Se. The laboratory data is qualitatively consistent with previous laboratory studies involving ion irradiation of H2O–ice and the trend with energy is reasonably fit by the most recent model for electron induced sputtering of H2O–ice, although the model overestimates the yield by at least a factor of three. In addition, we show that the irradiation history of our H2O–ice samples can strongly influence the measured Y, as temporary enhancements in Y as high as a factor of six were observed, which we speculate is a result of the release of radiolytically-produced O2 that is trapped below the surface of our H2O–ice samples.