Imaging Molecules and Chemical Reactions by Scanning Tunneling Microscopy

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With the support of the Analytical and Surface Chemistry Program, Professor Chiang and her colleagues at the University of California-Davis are carrying out studies of the microscopic mechanisms of important model catalytic systems. The decomposition of heterocyclic molecules, the cyclization of acetylene to benzene, and the dehydrogenation of cyclohexene are the model systems being investigated. The use of scanning probe microscopy in these studies allows real space imaging of these reaction processes on the well-characterized palladium or platinum surface. Surface species reactivity is correlated with the presence of defects, steps, and co-adsorbates on these surfaces. Comparison of adsorbed species images with theoretically predicted images is used to identify the adsorbed species. An understanding of the details of heterogeneous catalytic reactions is useful for the design and optimization of catalytic process chemistry. Professor Chiang at UC-Davis is using molecular resolution scanning probe microscopic methods to examine the details of model catalytic reactions in real space. Adsorbed species reactivity is being correlated with the presence of defects, steps, and co-adsorbates on these model surfaces. Information obtained from these studies will be useful in the optimization of sulfur and nitrogen removal chemistry in refining petroleum feedstocks.