9407009 Abruna This research project, supported by the Analytical and Surface Chemistry Program, is directed at developing an understanding of the process of underpotential deposition of metals on metals. The effects of surface morphology and potential dependent distributional changes of interfacial species will be probed using a combination of dynamic electrochemical methods, X-ray scattering probes such as EXAFS and X-ray reflectivity, and UHV electron spectroscopic methods. Growth modes in the deposition of silver and copper on platinum electrodes will be examined, and the effect of the structure of the adsorbed layer on the metal deposition process will be characterized. This information is crucial to the understanding of electroplating and thin film growth. %%% The detailed mechanism of the electrochemical deposition of thin metal films on metal substrates is the focus of this research project. A unique combination of X-ray and electrochemical methods will be used to provide insights into the effect of surface morphology and electrode-solution interfacial structure on the deposition process. This information is useful for understanding technologically important processes such as electroplating and corrosion inhibition.