In this research project supported by the Analytical and Surface Chemistry Program, the diffusion of H on Re surfaces will be investigated using field emission fluctuation methods. This experimental information will be supplemented by Monte Carlo simulations of the surface diffusion process, in order to extract microscopic diffusion parameters for this system. Tunneling diffusion on stiff lattices will form the focus of this aspect of the research work. These studies will be extended to the diffusion of H and O and CO on Ta surfaces as well. A second aspect of the work to be carried out in this project addresses the question of metallicity in metal monolayers. Gold and iron overlayers deposited on refractory metal substrates, with chemisorbed molecular spacers, will be investigated. Electron energy loss measurements, work function measurements, and ultra-violet photoelectron spectroscopy will be combined to probe the metallicity of these monolayers. Understanding the microscopic mechanism of diffusion of atomic and molecular species on transition metal surfaces is crucial to the understanding of a number of important technologies, ranging from heterogeneous catalysis to electronic materials processing. The present research project focusses on experimental and calculational studies of this important physical process. In addition, the question of the metallic nature of thin film overlayers is important to the understanding of thin film growth and electronic device fabrication. The second aspect of this project addresses questions related to the metallic nature of metal overlayers.
