Sputtering of water ice by keV electrons at 60 K

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 similar to 16, indicating that there is a clear relation between Y (H2O) and S-e. 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 O-2 that is trapped below the surface of our H2O-ice samples.