Spectroscopic Studies of Structures and Defect Activities ofIcy Clusters and Thin Films

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Professor Devlin is supported by a grant from the Experimental Physical Chemistry Program to study icy thin films and clusters, including crystalline ice, amorphous ice and acid hydrates using infrared spectroscopy. The data acquired will enhance our understanding of natural processes such as nucleation and growth of icy particles in the atmosphere, the molecular-level processes at ice surfaces that lead to charge separation in electrical storms, and proton conductivity across and along biomembrane-water interfaces. The influence of surfaces, interfaces and intense near-infrared radiation on point-defect activities (ionic: hydrogen and hydroxyl ions, and orientational: L and D) of hydrogen-bonded solids will be examined in icy thin films and clusters, including ice I, amorphous ice, acid hydrates and clathrate hydrates. Fourier transform infrared and Raman spectroscopies will be used to monitor isotopic exchange rates for samples containing nonequilibrium quantitites of protium and deuterium isotopomers. These experiments will take advantage of a technique recently developed by Devlin based on observations that the absorption bands of OH groups that dangle from the surfaces are distinct from the OH groups which are involved in hydrogen bonds. These methods will be applied to the evaluation of the hypothesis that phase transitions of icy substances are critically dependent on the availability of mobile orientational defects.