Effect of surface steps on the diffusion of adsorbates investigated with angle-resolved photoelectron spectroscopy

To investigate the surface diffusion of chemisorbed H on Ag/Au(111) thin films with surface steps, we characterized the distribution of H atoms on the surface by measuring the Shockley states of these surfaces with angle-resolved photoelectron spectroscopy. Our results show that H atoms tend to diffuse and to remain on the terrace at the lower side of the surface steps during annealing. This diffusive behavior is explained qualitatively through the existence of an Ehrlich-Schwoebel potential barrier associated with the surface steps.