Structure and Reactivity of Epitaxial Metal Films

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This project is in the general area of analytical and surface chemistry and in the subfields of structure and growth of thin films and heterogeneous catalysis. Variation of the electronic properties and structure of thin metal and metal alloy films will be investigated and correlated with their catalytic activity. The films will be grown epitaxially on metal and mica substrates. Their growth mode and structure will be characterized by low energy electron diffraction, Auger electron spectroscopy and helium scattering. Chemical rections to be studied include the dissociation of carbon monoxide, atomic exchange reactions of molecular hydrogen and deuterium, and the reactions of hydrocarbons with atomic hydrogen. Molecular beams will be employed to avoid wall effects. Ensemble effects will be investigated using gold-palladium alloy films, employing ion surface scattering spectrometry to determine the alloy surface layer composition. The results of these catalytic studies with thin films will provide a correlation between chemical reactivity on large metal single-crystal surfaces under very low pressure conditions and reactivity on supported metal crystallites, with characteristic diameters 20- 100 Angstroms, of the type commonly employed as comercial catalysts under high pressure conditions. Effects of dimensionality on electronic properties will be assessed.