The proposed research consists of studies of chemical processes of importance in the atmosphere which involve cloud particles. There are strong indications that polar stratospheric clouds are chemically very active, transforming stable chlorine compounds to a form that efficiently promotes ozone depletion. The studies in this proposal are aimed at elucidating the mechanism for such processes, and at measuring parameters such as chemical reaction rates, which are needed to model the behavior of the polar stratosphere and to predict future effects of the release of man-made chlorofluorocarbons. More specifically, the PI plans to characterize the various ices of atmospheric interest (which consist of water with varying amounts of HNO3, H2SO4 and HCl) by means of thermal analysis techniques such as differential scanning calorimetry, and by infrared and ultraviolet spectrophotometry and to measure the vapor pressures of HCl for the various ices as a function of the ice composition via mass spectrometry. The PI also plans to determine reaction probabilities for ClONO2 and N2O5 vapors interacting with ices containing amounts of HCl which are appropriate for stratospheric conditions.
