Chlorine Adsorption on Ni（l10）

The adsorption and thermal desorption of cholrine on Ni（ll0） at different tempestures have been studied with UPS, XPS, AES and work function measurements. Chlorine dissociatively adsorbs via a precursor state and remains chemisorbed on Ni（l10） surface. Sticking probability keeps essentially constant over an initially wide.coverage range. Increasing or the substrate temperature cause only a sligrt decrease in the initial sticking probability So and the saturation coverage θ₈. at 193-723K. However, above-800K a substantially decrease of S₀ and θ₈, occurs due to the chlorine desorption into the vacuum. Heating the chlorine adsorbed surface to -700K causes the chlorine desorption but does not lead to incorporration of chlorine atoms into the bulk, indicating a high activation enrgy of penetration for Cl atoms. The isothermal desorption of chlorine was found to follow 1.5 order kinetics between 823 and 923K,which implies that the formation or the surface complex NiCl₂（a） is the rate determing step.The influence of the surface temperature and the lateral interaction at the surface on the desorption kinetics are discussed in detail.