Mobility of Ag adatoms on Ag(100)

Low-energy ion scattering (LEIS) measurements have been performed to study self-diffusion on a stepped Ag(100) surface. The Ag adatoms were produced by means of ion beam irradiation with a total coverage of a few percent of a monolayer (ML). In the applied geometry for the LEIS-TOF (time-of-flight) measurements, with a glancing exit angle of 5 degrees and the scattering plane parallel to the step edges, high sensitivity is obtained for isolated, immobile adatoms on the surface. In case the adatoms are mobile, they will be absorbed at the steps and no yield is expected. The LEIS yield due to visible adatoms produced by irradiation was measured as a function of decreasing irradiation temperature. A sharp increase in this yield was observed at 160(5) K. It was also observed that an adatom coverage produced at lower temperatures starts diminishing when the temperature exceeds 160(5) K. From this value we estimated the activation energy for self-diffusion on Ag(100) to be 0.40(5) eV.