ADSORPTION OF HYDROGEN ON THE PT(111) SURFACE FROM LOW-ENERGY RECOIL SCATTERING

We have shown that low-energy recoil scattering (LERS) can be used to detect hydrogen on a Pt(111) surface at 150 K and that this method pro vides a direct probe for locating the positions of adsorbed hydrogen o n a surface. It was found: (1) the initial sticking coefficient of a H atom is s(0)(theta)approximate to 0.1; (2) from the isothermal anneal ing, the activation energy of H atoms adsorbed on the surface is evalu ated to be 0.3 eV; and (3) the H atoms occupy fee-adsorption sites on the Pt(111) terraces at a height of approximately 1.2 Angstrom above t he first layer of Pt atoms. (C) 1997 Elsevier Science B.V.