Reaction of methane with nickel single crystal surfaces and the stability of surface nickel carbides

The decomposition of methane on several low index faces of nickel has been studied by Auger electron spectroscopy. Differences between the (111), (110) and (100) plane are found, both in sticking probability and decomposition kinetics. Carbon deposited on the (110) and (100) plane diffuses into the bulk at higher temperatures (600-700 K). A model for this process is proposed from which the binding energies of several kinds of surface carbides may be derived.