Book Description

Molecular beam scattering techniques have firmly established themselves among the major tools for studying the kinetics and dynamics of gas- surface interactions. They have also proven themselves to be of great use in materials synthesis, most notably being used for the molecular beam epitaxial (MBE) growth of semiconductor substrates and superlattices. During the past few years our research group has been very active in developing new and quite general molecular beam techniques for studying the kinetic mechanisms of surface chemical reactions. We have, in particular, focused much of our attention on extending traditional molecular beam measurements to allow us to routinely explore coverage dependent kinetic mechanisms under essentially linearized conditions. These efforts have been quite successful. Our three molecular beam scattering arrangement is unique in the world, and significantly expands the range and power of modulated beam reactive scattering for studying complex kinetics at surfaces. The experimental methodology we have developed utilizes two continuous, independently adjustable beams to establish a desired steady state surface concentration, while a weaker modulated third beam induces small concentration perturbations around the selected steady state. This linearized approach permits the coupled differential equations which represent the overall surface reaction mechanism to be solved perturbatively, yielding quantitative information about the various kinetic steps which comprise overall reaction mechanisms.