The azimuthal dependence of H diffusion on a 0.1º-miscut (111) surface was studied, as a function of temperature, by using optical techniques. On the basis of the observed dependence, it was concluded that the additional energy barrier which was required, for a H adatom to cross a [110] step-edge, was less than 0.060eV (1.5kcal/mol).

Azimuthal Dependence of Classical Over-Barrier Hopping Diffusion of Hydrogen on a Vicinal Ni(111) Surface. E.Nabighian, X.D.Zhu: Physical Review B, 1998, 58[12], R7552-5