This research deals with the diffusion of adatoms and molecules on metals and semiconductors. Three specific investigations will be performed. 1) The diffusion of hydrogen across step edges on vicinal Ni(111); 2) the classical and quantum diffusion of hydrogen on Cu(111); as well as 3) the classical and quantum diffusion of hydrogen on Nb(100) surfaces will be investigated. Among the questions to be answered are 1) what is the potential energy barrier for a hydrogen atom to cross an atomic step that separates two Ni(111) terraces? 2a) Since the hydrogen absorption on Cu(111) is similar to that on Ni(111), will the quantum diffusion of hydrogen on Cu(111) emulate that on Ni(111)? and 2b)How does the quantum diffusion of hydrogen on Cu(11) compare with that of hydrogen and positive muons in Cu?; and similar questions with respect to the diffusion of hydrogen on Nb(100). These investigations will provide an improved understanding of the interactions between atoms/molecules and surfaces. Graduate students and post doctoral research associates will participate in these researches. %%% The bonding of atoms and molecules to metallic surfaces plays an extremely important role in modern technology. Catalysis, adhesion of coatings, corrosion, and other phenomena all depend on the interactions between atoms and molecules and metallic surfaces on which they are adsorbed. One of the important parameters that describes these interactions is the diffusion of atoms across the surface. The interaction between hydrogen atoms and well characterized metal surfaces constitutes a model system for such investigations. The results of these studies will bring about a better understanding of the behavior of atoms and molecules adsorbed on metal surfaces and ultimately an improved technology. Graduate students and post doctoral research associates participate in this research. They will thereby acquire skills and training in a field with great potential for employment during the next several decades of the 21st Century. ***
