Dynamics and Kinetics on Surfaces Exhibiting Defects

Abstract

This paper considers dynamics and kinetic phenomena on surfaces with defect structures. Quantum mechanical scattering as well as kinetics and diffusion processes are treated as examples. In the case of quantum mechanics, a theoretical formulation is presented capable of handling atomic disorder on surfaces. The aproach is based on an approximation which is best in the quantum long wavelength regime. Some simple illustrations considering scattering off ordered and disordered lattices will be presented. The second part of the paper considers the steady state non-linear reaction diffusion equations used to describe adsorption, desorption, diffusion and reaction on surfaces with macroscopic scale defects. These latter defects may arise due to inherent faulting of the lattice or foreign material on the surface. Defects within a mean diffusion length of each other are shown to exhibit cooperativity in their chemical properties. Finally, in the last portion of the paper, reaction-diffusion models are again considered from a different perspective. In this case, all of the non-linear chemical or desorptive aspects of the problem are restricted to the edges of the defect sites and the intervening surface is assumed to be characterized by adsorption, desorption and simple diffusion. These physically realistic models clearly show the capability of multiple steady states existing on active chemical surfaces. a variety of non-linear surface phenomena could possibly be important in appropriate gas-surface systems.