Coverage dependence of anisotropic surface diffusion: CO/Ni(110)

Anisotropic surface diffusion of CO on Ni(110) and its coverage dependence have been measured using the method of linear optical diffraction from monolayer gratings. No coverage dependence below 0.7 ML was observed. Above 0.7 ML, the short-range CO-CO interaction due to orbital overlap seems responsible for the observed reduction of the diffusion activation energy with CO coverage. The corresponding interaction energy is estimated to be 0.077 eV from the result. Anisotropy in the surface diffusion is not significantly affected by the CO-CO interaction.