Atomic jump lengths in surface diffusion: Re, Mo, Ir, and Rh on W(211)

Abstract

Measurements with the field ion microscope have been made of the distribution function governing the displacements of a single metal atom diffusing on W(211). It is shown that by comparing such measurements with the predictions of random walk models, the contributions of jumps of different lengths to the overall diffusion can be ascertained, even if diffusion is dominated by transitions between adjacent sites. Extensive observations for rhenium, as well as for molybdenum atoms on W(211) are best represented by a symmetric random walk between nearest-neighbor sites, without any contribution from longer jumps. For iridium and rhodium atoms, however, double jumps do appear to participate in the diffusion, but amount to only ≊3% of the total.