Modeling heterogeneous atomic recombination and molecule conversion

摘要

Various surface kinetics studies distinguish adsorption into physisorption and chemisorption. Usually, chemisorption sites are assumed to be the "active sites," in which recombination takes place. Herein a generalisation of this simple scheme is presented, by introducing chemisorption sites with different binding energies. In particular, "weak-chemisorption" sites are additionally considered. They are characterised by a binding energy which is strong enough as to render them active sites; but, contrary to the (normal) chemisorption sites, not strong enough to completely prevent thermal desorption. The implications of this assumption in recombination studies and its range of validity are discussed.