Observation of surface diffusion of adsorbates on metal surfaces by photoemission electron microscopy (PEEM)

Thermal desorption by means of a focussed infrared laser pulse creates an adsorbate-free spot on the surface with a diameter of about 0.1 mm which is subsequently filled by surface diffusion. The temporal evolution of the concentration profile may be monitored by photoemission electron microscopy (PEEM), from which data diffusion coefficients of adsorbates may be evaluated along any direction on the surface. First applications are demonstrated for the CO/Pt(110) system.