Collective Motion and Structural Order in Adsorbate Vibrational Dynamics

Abstract

A simple, broadly applicable theory is developed to describe resonant vibrational coupling between adsorbates and a substrate lattice. This is one of the principal mechanisms governing the relaxation of adsorbate vibrations. This theory can be applied to widely varying surface coverages and arbitrary overlayer structures, and it correctly incorporates collective adsorbate motion, which has been shown to have a critical impact on the relaxation dynamics. Vibrational lifetimes predicted by this theory are in excellent quantitative agreement with experiments on adsorbate systems ranging from a diffuse, disordered overlayer to a dense, periodic overlayer. {copyright} {ital 1998} {ital The American Physical Society }