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M. Fama, D.M. Pugh, B.D. Teolis, R.A. Baragiola (University of Virginia)
Optical interference in the UV and visible has been used to study the effect of ion bombardment (80 keV molecular oxygen) on low density (highly porous) solid water films at temperatures between 30 and 130 K deposited onto a quartz crystal microbalance (QCM) at large growth angles. The combination of the QCM together with the reflectivity method leads to a very precise determination of the film density before, during, and after the ion beam exposure. At very low doses, where the amount of sputtered water molecules is < 30 bilayers, the porosity decreases quickly to a saturation value. Astronomical implications will be discussed for the outer solar system.