The theory of desorption

Abstract Desorption is the process in which an atom or molecule leaves the surface of a condensed phase, usually a solid. The departure may be caused by some external influence, such as electron bombardment, in which case it is referred to as stimulated desorption. I t may be due entirely to thermal fluctuations in the surface. As with all processes involving atoms or molecules at surfaces, the microscopic understanding of desorption is currently of great experimental and theoretical interest. However, desorption is essentially a statistical, macroscopic process; the details of the microscopic mechanisms can only appear in an averaged form in either experimental or theoretical results. Nevertheless, it is of interest to learn as much as possible from this technique and many papers have consequently been written about it. This article is a tutorial review of the current theoretical position and, thus, attempts to define the present level of understanding.