Low-energy electron microscopy was used to study the mechanisms of thermal smoothing on Rh(001) surfaces at high temperatures. By examining the change in areas of 2-dimensional islands as a function of time and temperature, it was found that smoothing from 1210 to 1450K was limited by the rate of surface diffusion on terraces, and not by bulk vacancy diffusion as observed in other systems in the same temperature range. However, the activation energy which was measured for island decay was inconsistent with previous measurements and calculations of the activation energy of surface diffusion and adatom formation energy. This inconsistency, combined with an unexpectedly large activation entropy, suggested the operation of a surface transport mechanism other than simple hopping of adatoms across the surface.

Surface-Diffusion-Limited Island Decay on Rh(001). G.L.Kellogg, N.C.Bartelt: Surface Science, 2005, 577[2-3], 151-7