Kleinle, Gerald; Wintterlin, Joost; Ertl, Gerhard; Behm, Rolf Jürgen; Jona, Franco; Moritz, Wolfgang
Reconstruction and subsurface lattice distortions in the (2 × 1)O-Ni(110) structure: A LEED analysis.
In: Surface Science, Vol. 225, Nr. 1-2: S. 171-183
LEED analysis of the reconstructed (2 × 1)O-Ni(110) system clearly favors the “missing row” structure over the “saw-tooth” and “buckled row” models. By using a novel computational procedure 8 structural parameters could be refined simultaneously, leading to excellent R-factors (RZJ = 0.09, RP = 0.18). The adsorbed O atoms are located 0.2 Å above the long bridge sites in  direction, presumably with a slight displacement ( 0.1 Å) in [1 0] direction to an asymmetric adsorption site. The nearest-neighbor Ni---O bond lengths (1.77 Å) are rather short. The separation between the topmost two Ni layers is expanded to 1.30 Å (bulk value 1.25 Å), while that between the second and third layer is slightly contracted to 1.23 Å. The third layer is, in addition, slightly buckled (±0.05 Å). The results are discussed on the basis of our present general knowledge about the structure of adsorbate covered metallic surfaces.