Adsorbate surface diffusion: The role of incoherent tunneling in light particle motion

Abstract

The role of incoherent tunneling in the diffusion of light atoms on surfaces is investigated. With this purpose, a Chudley¿Elliot master equation constrained to nearest neighbors is considered within the Grabert¿Weiss approach to quantum diffusion in periodic lattices. This model is applied to recent measurements of atomic H and D on Pt(111), rendering friction coefficients that are in the range of those available in the literature for other species of adsorbates. A simple extension of the model has also been considered to evaluate the relationship between coverage and tunneling and therefore the feasibility of the approach. An increase of the tunneling rate has been observed as the surface coverage decreases.This work has been partly supported by the Ministerio de Economía y Competitividad (Spain) under Projects FIS2010-22082 and FIS2011-29596-C02-01. AS would also like to thank the Ministerio de Economıa y Competitividad for a “Ramón y Cajal” Research Grant and the University College London for its kind hospitality.Peer Reviewe