Dynamics of gas–surface interactions and reactions

Abstract

Heterogeneous catalysis is responsible for a significant fraction of the output of the chemical industry. The kinetics of surface chemical reactions have therefore been studied extensively. One must not however think that surface processes are synonymous with catalysis. The study of lubrication, known under the modern name of tribology, is very active. For example, what determines the rate of information storage and retrieval is the speed with which the reading head can move over the hard disk at a very low elevation. Other familiar examples of surface processes, such as corrosion, come to mind. Microelectronics and nanostructures on surfaces are also benefiting from and contributing to progress in surface science. An important development is that imaging techniques initially introduced for the probing of surface structure on the atomic scale are revealing details about reaction dynamics. Scanning tunneling microscopy (STM) has been particularly useful. Our intent in this chapter, as in the rest of this volume, is to examine the molecular-level description. We shall thus make no attempt to review the extensive literature on the macrolevel description but proceed immediately to the microlevel, considering first elastic and energy transfer collisions and then “pre-reactive” and reactive collisions. Many of the experimental and theoretical techniques are closely related to those used to study collisions in the gas phase, but both the experiments and the collision dynamics per se are more complicated because the surface is never really passive and may even be one of the reactants, as in the etching of silicon for microelectronics.