Low Energy Electron Diffraction (LEED), Auger Electron Spectroscopy (AES), Thermal Desorption (TD) Electron Spectroscopy for Chemical Analysis (ESCA) Studies. Summary of Progress, July 1979-March 1981

摘要

The adsorption/desorption of several molecular species which are important in developing an understanding of the methanation process, CO, O sub 2 , H sub 2 and CH sub 4 , has been studied in detail using several surface analysis techniques, namely, Low Energy Electron Diffraction, Auger Electron Spectroscopy, Thermal Desorption, and Electron Spectroscopy for Chemical Analysis. Studies have also been undertaken to measure surface dipoles of adsorption molecules using the reverse bias technique. The surface studies have been carried out on three different single crystal surfaces: a perfect Ni(111) surface; a Ni(111) surface with small angle boundaries and a Ni(100) surface. The two Ni(111) crystals were also contaminated with sulfur by causing bulk sulfur, which was present at the ppm level, to diffuse to the surface of the crystals to form a maximum coverage of theta approx. = 0.30. These studies have produced useful and important data which provide a better insight into how these gaseous molecules interact both physically and chemically with the Ni surfaces for a wide variety of experimental conditions of temperature and pressure. From the data obtained to date these interactions appear to be far more complex than has previously been suggested, involving surface reconstructions and in some cases the solution of either the adsorbed species or a dissociated species in the bulk materials. (ERA citation 08:017017)