The structure of oxygen-induced reconstruction on Cu{1 0 0}-c(2 × 2)–Pt surface alloy: the Pt/Cu{1 0 0}-(2 × 2)–O

Adsorption of 0.25 ML oxygen on the Cu{1 0 0}-c(2 × 2)–Pt surface alloy followed by a brief thermal activation to 500 K and recooling to room temperature leads to the formation of a surface structure with a p(2 × 2) periodicity. The structure of this Pt/Cu{1 0 0}-(2 × 2)–O has been determined by quantitative low energy electron diffraction (LEED) calculations using the symmetrised automated tensor LEED (SATLEED) program. The results of the calculations suggest that simple p(2 × 2) overlayers can be ruled out in favour of an oxygen-induced surface reconstruction. The favoured model (Pendry R-factor=0.23) consists of a mixed c(2 × 2) CuPt underlayer below a reconstructed Cu{1 0 0} outermost layer with oxygen atoms occupying a slightly displaced fourfold hollow sites above second layer Pt atoms relative to the original unreconstructed surface.