Adsorption Kinetics of H2/Ni and its Dependence on Surface Structure, Surface Impurities, Gas Temperature and Angle of Incidence

We have for the first time determined the change in the angular distribution function of the adsorption probability with beam temperature. This change is an extremely sensitive indicator for the particular adsorption dynamics at work; it is used to determine the physical effects of surface impurities and surface defects as well as surface structure in the adsorption of hydrogen on nickel. On all single-crystal surfaces investigated there seems to be activated adsorption with a parallel channel of nonactivated adsorption through a precursor. Defects and oxygen impurities generate additional adsorption sites for nonactivated adsorption. These sites are predominantly active at low temperatures.