A study was made, using low-energy electron microscopy, of fluctuations in step edges on (111) faces at 1190 to 1520K. The relaxation times, at below 1400K, varied in proportion to q3 (where q was the wave vector). Above 1400K, it varied as q2 while the observed activation energy changed from 1.25 to 2.75eV. It was shown that surface diffusion was responsible for the rates at low temperatures, and that bulk vacancy diffusion became dominant at above 1400K. It was deduced that a similar cross-over occurred for steps on metal surfaces. The step stiffness was deduced to be equal to 0.175eV/nm at 1500K.

Crossover from Bulk to Surface Diffusion in the Fluctuations of Step Edges on Pt(111). M.Ondrejcek, W.Swiech, G.Yang, C.P.Flynn: Philosophical Magazine Letters, 2004, 84[2], 69-77