FTIR STUDIES OF ANNEALING PROCESSES IN LOW-TEMPERATURE PURE AND MIXEDAMORPHOUS ICE SAMPLES

Thin ice films produced by vapor deposition upon a bare CsI window as well as upon predeposited rare-gas layers or by co-deposition with rar e gases may bear similarities to ices in the stratosphere and interste llar space. It was found that infrared band peak positions, bandwidths , and integrated intensities, especially those of the coupled and deco upled OH stretching mode bands, are very sensitive to structural modif ications in the solid ice layers. Abrupt changes in the temperature-de pendent curves of these parameters signify processes such as annealing , morphological changes, phase transitions, release of internal gas in clusions and of externally adsorbed gases, and ice grain ejection. It was shown that (H2O)(as) annealing is a gradual process taking place e ven at very low temperatures. Spectroscopic similarities exist between the bulk porous ice formed by rare gas release and supercooled water solid and both differ significantly in their infrared spectra from the usual vapor-deposited amorphous ices.