The migration of H isotopes on the (100) surface was studied by using laser-induced thermal desorption. The temperature dependence was measured at between 211 and 263K. It was found that H diffused more rapidly than D throughout this range. The activation energy was lower for H (3.5kcal/mol) than for D (4.4kcal/mol). This difference was compensated for by the pre-exponential factor to some extent; which was larger for D (0.0085cm2/s) than for H (0.0025cm2/s). The co-adsorption of D and H had no effect upon the diffusion constants of the individual species when their relative concentrations were varied from 30% to 100%.

Isotope Effects in Surface Diffusion: Hydrogen and Deuterium on Ni(100). D.R.Mullins, B.Roop, S.A.Costello, J.M.White: Surface Science, 1987, 186[1-2], 67-74

Table 101

Parameters for the Diffusion and Migration of

H Isotopes in Ni in an External Electric Field