Electric field inhibition and promotion of exchange diffusion on Pt(001)

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Abstract
Direct observations of a Pt adatom migrating on the Pt(001) plane in the presence of an externally applied electric field show that a positive field raises, and a negative field lowers, the activation barrier for the adatom–substrate-atom exchange process. At field strengths of 1.5 V/Å and above, inhibition of the exchange mechanism is sufficient to change the diffusion mode from exclusively exchange displacements to a mode that includes hops. The effect of the electric field is explained by an electron-transfer process which changes the bonding of the adatom to neighboring surface atoms.