Tracer Diffusion on Correlated Heterogeneous Surfaces

SAPAG, K.; BULNES, F.; RICCARDO, J.L.; PEREYRA, V.; ZGRABLICH, G.

LANGMUIR

AMER CHEMICAL SOC

Año: 1993 vol. 9 p. 2670 - 2675

0743-7463

Tracer diffusion on heterogeneous surfaces is studied by Monte Carlo simulations. The energetic surface topography is described by a dual site-bond model where site and saddle points (bond) energies are incorporated in a general way. The case of uniform energetic distributions is studied and the behavior of the diffusion coefficient is analyzed for several topographies: random traps, random barriers, random sites-bonds, correlated traps, correlated barriers, and correlated sites-bonds, for different correlation degrees. The conditions under which the temperature dependence of the tracer diffusion coefficient shows a non-Arrhenian behavior are discussed. The jump correlation factor is also analyzed since the jump mechanism plays a fundamental role in this treatment. Surface diffusion emerges as an important tool for the characterization of the energetic topography on heterogeneous surfaces. © 1993, American Chemical Society. All rights reserved.