The diffusion rate of Xe on Ni(111) was measured at 30 to 60K for coverages (θ) of 0.04 and 0.16. It was found that the diffusion was characterized by a small activation energy and an unusually small diffusivity. The results were described by:

θ = 0.04:     D(cm2/s) = 2 x 10-9exp[-0.33(kcal/mol)/RT]

θ = 0.16:     D(cm2/s) = 3 x 10-8exp[-0.40(kcal/mol)/RT]

E.Nabighian, X.D.Zhu: Chemical Physics Letters, 2000, 316[3-4], 177-80