The diffusion of Pb atoms embedded in a Cu(001) surface was studied using atom-tracking scanning tunneling microscopy. By comparing these observations with simulations based on first-principles electronic structure calculations, it was deduced that the diffusion occurred by a vacancy-mediated mechanism in which the vacancy was attracted by the embedded Pb atom.

The Importance of Pb-Vacancy Attractions on Diffusion in the Pb/Cu(001) Surface Alloy. M.L.Anderson, N.C.Bartelt, B.S.Swartzentruber: Surface Science, 2003, 538[1-2], 53-8