The diffusion of various adatoms upon the (211) plane of W was studied by means of field ion microscopy. Particular attention was paid to the internal consistency of the measurements. Diffusion appeared to occur in accord with the simplest of models, and the pre-exponential factor differed little between adatoms (19.2 for Re, 19.0 for W, 16.4 for Mo, 15.4 for Ir, and 12.4kcal/mol for Rh). The data for Re could be described by:

D (cm2/s) = 0.0073 exp[-19.2(kcal/mol)/RT]

There was no sign of any anomaly in the diffusion dynamics. It was suggested that the activation energies for diffusion over a flat surface could be correlated with bulk thermodynamic data for vaporization.

S.C.Wang, G.Ehrlich: Surface Science, 1988, 206[3], 451-74