The interaction of atoms and molecules with solid surfaces I—The activation of adsorbed atoms to higher vibrational states

Abstract

A first step towards an understanding of the many important chemical phenomena which are known to take place at solid surfaces is to discover how atoms behave when adsorbed on a surface. They may continue in one place vibrating about a mean position or, in certain circumstances, they may migrate from one part of the surface to another or they may be ejected from the surface altogether by the thermal agitation of the solid below them. It is of some importance to know how often they change from one such state to another and what are the controlling influences involved. The processes of adsorption and evaporation have often been considered by thermodynamic methods, but these, though powerful, deal only with statistical effects and are independent of any picture of the mechanism involved. They are able to give the fraction of atoms in each energy state of the assembly at a given moment, but they are not capable of providing any information as to the probabilities of transfer from one state to another.