Diffusion in surface layers

Surface diffusion has only recently become a topic of wide interest. This neglect is surprising, as diffusion plays an important role in surface processes. It has long been appreciated that the movement of reaction intermediates over catalyst particles is one of the significant steps in heterogeneous catalysis; this is well illustrated in Professor Ertl's review.1 Studies of surface diffusion can also provide insights into the nature of the bonding at an interface. Finally, in crystal and thin film growth as well as in sintering, material transport by self–diffusion over the surface is all important.2,3 That despite all this surface diffusion has not received more attention must in large measure be ascribed to experimental difficulties inherent in such studies. Only recent developments in analytical techniques have made it possible to carry out measurements of surface diffusion with confidence and relative ease.