An X-ray crystallographic structure determination was made of the 5 x 5 (001)Mo/O surface. This was the penultimate structure in a sequence of ordered states which was obtained by high-temperature desorption from the oxidized surface. The O induced a reconstruction, with one Mo atom missing from the surface unit cell and with O atoms occupying the exposed 3-fold sites. The O sat asymmetrically in these sites and induced a rotational distortion of the remaining uppermost Mo atoms, which clustered together. The asymmetry was attributed to partial direct bond formation between surface Mo-O clusters since this was apparently not mediated by any significant second-layer displacements.

I.K.Robinson, D.M.Smilgies, P.J.Eng: Journal of Physics - Condensed Matter, 1992, 4[27], 5845-54