Bismuth on copper (110): analysis of the c(2x2) and p(4x1) structures by surface x-ray diffraction

Surface X-ray diffraction has been used to analyze the atomic structures of the Cu(110)-c(2 x 2)-Bi and Cu(110)-p(4 x 1)-Bi reconstructions with submonolayer coverages. A quasi-hexagonal c(2 x 2) adlayer structure is formed when half a monolayer of bismuth is deposited; the coverage corresponds to 1.08 x 10(-15) atoms cm(-2). There is one Bi atom per c(2 x 2) surface unit cell, and the nearest-neighbor distance on the planar overlayer was found to be 4.43 Angstrom. In the case of the p(4 x 1) reconstruction formed at a coverage of 0.75 monolayers, both the in-plane and out-of-plane data are in excellent agreement with a model in which every fourth Cu row in the [001] direction of the topmost layer is replaced by Bi atoms to form a substitutional surface alloy. (C) 1997 Elsevier Science B.V.