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Surface migration

المؤلف:  Peter Atkins, Tina Overton, Jonathan Rourke, Mark Weller, and Fraser Armstrong

المصدر:  Shriver and Atkins Inorganic Chemistry ,5th E

الجزء والصفحة:  708

2025-10-19

661

Surface migration

Key point: Adsorbed atoms and molecules migrate over metal surfaces. The surface analogue of fluxional mobility in clusters is diffusion, and there is abundant evidence for the diffusion of chemisorbed molecules or atoms on metal surfaces. For example, adsorbed H atoms and CO molecules are known to move over the surface of a metal particle. These diffusion pathways generally involve the adsorbed molecules mov ing through a variety of different coordination sites on the metal surface. So, for example, CO migration can result from a molecule moving between sites interacting with one (terminal CO) and between two and four (bridging CO) metal atoms on the surface. The energy barrier to this process is relatively low, a few tens of kilojoules per mole, and thus migration rates are very high under typical catalytic reaction conditions. This mobility is important in catalytic reactions as it allows atoms or molecules to find and approach one another rapidly.