Direct observations of a Pt adatom, migrating on the (001) plane in the presence of an externally applied electric field, showed that a positive field increased (and a negative field decreased) the activation barrier for the adatom-substrate-atom exchange process. At field strengths of 15V/nm and above, inhibition of the exchange mechanism was sufficient to change the diffusion mode from exclusively exchange displacement to a mode which included hops. The effect of the electric field was explained in terms of an electron transfer process which changed the bonding of the adatom to neighboring surface atoms.

G.L.Kellogg: Physical Review Letters, 1993, 70[11], 1631-4