The traditional view of the surface diffusion of metal atoms on metal surfaces was that atoms carry on a random walk between nearest-neighbor surface sites. Through field ion microscopic observations and molecular dynamics simulations this picture was changed completely. Diffusion by an adatom exchanging with an atom of the substrate was identified on face-centered cubic (110), and subsequently also on face-centered cubic (100) planes. At elevated temperatures, multiple events were found by simulations in which an atom enters the lattice, and a lattice atom at some distance from the entry point pops out. Much 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 tungsten surfaces. As higher diffusion temperatures became accessible, additional jump processes could be expected to be revealed.

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