ANNEALING AND SUBLIMATION OF NOBLE-GAS AND WATER ICE FILMS

Using the double-paddle oscillator, we have measured the mass and the shear modulus of thin films of water ice, argon and neon during anneal ing at cryogenic temperatures. From this, we have determined the vapor pressure of the three solids, They are in good agreement with publish ed values for H2O and Ar; for Ne, they extend the vapor pressure to 10 (-11) torr, ten orders of magnitude smaller than previous measurements . On the polycrystalline noble gas films condensed at low temperatures , the shear modulus was found to increase logarithmically with the ann ealing time. This stiffening is similar to that observed previously fo r amorphous water ice, and is hence not connected to the amorphous str ucture of the latter.