The diffusion parameters for Ba on W(011) were shown to be related to phase transitions in the ad-layer. A surprisingly strong difference was found in the absolute values and in the coverage dependence of the diffusion parameters for Ba on the (011) planes of W and Mo. A considerably lower mobility of Ba on Mo was attributed to a larger contribution of covalent bonding for this substrate. It was concluded that the electronic structure, together with the atomic structure of a surface, played an important role in surface diffusion.

A.G.Naumovets, V.V.Poplavsky, J.S.Vedula: Surface Science, 1988, 200, 321-34