LOW-TEMPERATURE GROWTH-MECHANISM OF COBALT ON PT(110)(1 X-2)

Cobalt deposition on Pt(110)(1 x 2) at 100 K has been studied by photoemission of adsorbed xenon, work function measurements, Auger electron spectroscopy and LEED. Since the AES peak to peak heights for Pt as a function of the cobalt exposure can be fitted with a Beer-Lambert attenuation law, it is believed that the growth of the first layers proceeds through a pseudo layer by layer mechanism. This gives a calibration for cobalt fluxes. The work function passes through a minimum at the completion of the monolayer. Photoemission of adsorbed xenon reveals mixed adsorption sites in the range of a quarter to half of a monolayer of cobalt that could be associated with the filling of the valleys of the Pt(110)(1 x 2) by cobalt atoms. The lack of any LEED superstructure whatever the coverage, as well as the large width of the Xe 5p peaks are consistent with the formation of a rather disordered deposit.