Microscopic Observation of Step and Terrace Diffusion of Indium Atoms on Cu(111) Surfaces

The perturbed γγ angular correlation (PAC) method has been applied to study isolate 111 In probe atoms on vicinal Cu(111) surfaces. The properties of the observed electric-field gradients and the annealing behaviour suggest the existence of indium as step adatoms up to 140 K, above this temperature these adatoms convert into substitutional step atoms. At 220 K the indium probes finally start to diffuse into substitutional terrace sites. Desorption and diffusion into bulk was also detected. From the thermal conversion between the different sites activation energies have been estimated.