An X-ray crystallographic structure determination was carried out for the √5 x √5 Mo(001)/O surface. This was the penultimate structure in the sequence of ordered states obtained by high-temperature desorption from the oxidized surface. The oxygen induced a reconstruction with one Mo atom missing from the surface unit cell and O atoms occupying the exposed threefold sites. The O sits asymmetrically in these sites and induced a rotational distortion of the remaining top layer Mo atoms, which cluster together. The asymmetry could be attributed to partial direct bond formation between surface Mo-O clusters, since apparently this was not mediated by any significant second-layer displacements.

Cluster Formation in the Adsorbate-Induced Reconstruction of the O/Mo(001) Surface. I.K.Robinson, D.M.Dmilgies, P.J.Eng: Journal of Physics - Condensed Matter, 1992, 4[27], 5845-54