Carbon-60 induced structures on the clean and oxygen covered Cu(110) surface: competitive adsorption

The adsorption of C-60 molecules on a Cu(110) surface has been studied by scanning tunneling microscopy. On the clean Cu surface, the C-60 molecules nucleate into well-ordered islands with a distorted hexagonal structure which can be written as ((10)(+/-1) (0)(3)) using the matrix notation. The C-60 structure is unchanged upon oxygen adsorption, with a (2 x 1)-O structure forming around the C-60 islands. Predosing small amounts of oxygen at elevated temperature to create alternating stripes of clean Cu and (2 x 1)-O leads to elongated C-60 islands nucleated on the stripes of clean Cu, but with the same internal structure as on the clean surface. However, evaporation of C-60 on the fully saturated (2 x 1)-O surface leads to completely different C-60 structures, as weil as to the formation of small domains of the higher-density c(6 x 2)-O structure on the terraces. This is interpreted in terms of the C-60 molecules compressing the (2 x 1)-O structure in a competition with the oxygen atoms for surface area. (C) 1997 Elsevier Science B.V.