This research project, supported in the Analytical and Surface Chemistry Program, addresses questions of the detailed dynamics of gas-surface interactions. The objectives of the research are to develop an understanding of the detailed dynamics of dissociative chemisorption of simple diatomic molecules, and the recombination and desorption of adsorbed atoms from well characterized solid surfaces. Velocity resolved, polarization sensitive multi-photon ionization detection of scattered diatomic molecules and desorbed molecules resulting from atom recombination will be carried out. Novel studies of chemisorption of monoenergetic, aligned reagents will also be pursued. %%% Dissociation of molecules on surfaces, as well as recombination and desorption of molecules from the surface, are the principal elementary processes which underlie a wide range of important technologies, including catalysis, corrosion, and electronic device fabrication. This research project develops and applies state-of-the-art methods to the study of the detailed dynamics of these elementary processes. The information gained from these studies is essential in developing our basic understanding of these critical technologies.