A molecular-beam diffraction study of H₂ adsorption on Ni(110)

The adsorption of H2 on Ni(110) has been studied using He and H2 diffraction. We observe four homogeneous ordered phases as the coverage is increased between θ = 0.7 and θ = 1.6 at a substrate temperature of 100 K. Only two of these phases have been previously observed with LEED. Structural models consistent with the diffraction data are presented for three of these phases. We also observe that the adlayer undergoes on irreversible reconstruction upon heating to temperatures greater than 220 K. Although LEED investigations show a (1 × 2) pattern at high coverages for T > 220 K, our results show that the topmost layer is strongly disordered with a remnant (2 × 6) periodicity. The application of molecular beam techniques to the study of adsorbate covered surfaces is discussed. © 1981.