Diffusion in Crystalline Ice Measured Using Laser Resonant Desorption Techniques

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This research project, supported by the Analytical and Surface Chemistry Program, addresses the question of impurity analysis and diffusion in ice samples. Professor Steven M. George and his colleagues at the University of Colorado apply laser resonant desorption depth profiling methods to the analysis of species important in heterogeneous atmospheric chemistry and ice core analysis. In particular, hydrogen halides, nitric acid, various cations, sulfur containing molecules, and weak acids and bases implicated in atmospheric chemical processes are the subject of this investigation. Using an internal high pressure analysis cell, coupled with a load lock system to enable the analysis of environmental ice samples, the location and diffusion of these impurities in a range of ice samples are being examined. The results of this work are of significant importance to the development of accurate atmospheric models which include heterogeneous processes, as well as to the understanding of glacial ice cores and their historical record of environmental conditions. The understanding of environmental processes such as ozone depletion and global warming rely on the availability of detailed measurements of the location and motion of trace molecules in atmospheric ice samples and in glacial ice cores. The work of this research project is focussed on developing high spatial resolution laser desorption methods for the accurate and precise analysis of these sorts of environmental ice samples. The results of this work are crucial to our developing understanding of the atmosphere, both in current times and across the geological history of the earth.