Self-diffusion on reconstructed and nonreconstructed Ir surfaces

Abstract

Using the field ion microscope, we have studied random walk diffusion of single Ir atoms and small Ir atomic clusters on Ir surfaces. On the (1×1) Ir {001} surface, diffusion of Ir adatoms occurs by an atomic replacement mechanism along the 〈001〉 directions. On the (1×1) Ir {110} surface, self-diffusion occurs by atomic hopping along the 〈110〉 directions and by atomic replacement along the 〈001〉 directions. On the (1×2) reconstructed Ir {110} surface, self-diffusion occurs only by atomic hopping along the doubly spaced [1̄10] surface channels. Within the experimental accuracy, the pre-exponential factors are all in the 10−3 cm2/s range. Energies needed for these atomic replacements and the barrier heights for these atomic hoppings are also derived. Diffusion of diatomic clusters on the (1×1) Ir {110} surfaces has also been studied.