It was recalled that the traditional view of surface diffusion of metal atoms on metal surfaces was that atoms performed a random walk between nearest-neighbour surface sites. Field-ion microscopic observations and molecular dynamics simulations had completely changed this view. Diffusion via adatom exchange, with an atom of the substrate, was identified on face-centred cubic (110) planes, and subsequently also on face-centred cubic (100) planes. At elevated temperatures, multiple events were found by simulations in which an atom entered the lattice, and a lattice atom at some distance from the entry-point exited. At the same time, the contribution of long jumps spanning more than a nearest-neighbour distance was examined. Their rates were measured, and such transitions were found to contribute significantly; at least on W surfaces. It was expected that additional jump processes would be revealed as higher diffusion temperatures became accessible.

Jump Processes in Surface Diffusion. G.Antczak, G.Ehrlich: Surface Science Reports, 2007, 62[2], 39-61