A new method was presented for the determination of surface diffusion constants by using specular reflected thermal He scattering. The specular reflected He intensity was recorded in real time as a function of the surface coverage of the adsorbate and of the surface temperature. The experimental data were compared with a model calculation that was based upon rate equations for the generation and annihilation of adatoms and clusters. It was found that the activation energy for Ag surface diffusion on (100)Pd was 0.35eV, and that the attempt frequency was 2.7 x 109/s.

C.Félix, G.Vandoni, W.Harbich, J.Buttet, R.Monot: Surface Science, 1995, 331-333, 925-9