Anisotropic self-diffusion on Ag(1 1 0)

The mobility of silver atoms adsorbed on Ag(1 1 0) was investigated along the 〈1 1̄ 0〉 and 〈0 0 1〉 azimuthal directions by means of energy resolved He atom scattering. The results obtained in the temperature range up to 775 K exhibited a strong anisotropy. Above 600 K adsorbed atoms were observed to diffuse only along the 〈1 1̄ 0〉 azimuth. Information on the diffusion process was gained investigating the evolution of the quasi-elastic peak broadening with the parallel momentum transfer and with the temperature. In particular, the main diffusion mechanism was pointed out, the diffusion coefficient and the effective diffusion barrier were measured. The results were compared with the corresponding estimations from molecular dynamics calculations.