Aromatic interactions in the close packing of phenyl-imides at Cu(1 1 0) surfaces

The oxidation of aniline at Cu(1 1 0) surfaces at 290 K has been studied by XPS and STM. A single chemisorbed product, assigned to a phenyl imide (C6H5N(a)), is formed together with water which desorbs. Reaction with preadsorbed oxygen results in a maximum surface concentration of phenyl imide of 2.8 × 1014 mol cm−2 and a surface dominated by domains of three structures described by 4 0 2 2 , 4 0 - 1 2 and 4 0 1 2 unit meshes. However, concentrations of phenyl imide of up to 3.3 × 1014 mol cm−2 were obtained from the coadsorption of aniline and dioxygen (300:1 mixture) resulting in a highly ordered biphasic structure with 3 0 - 1 2 and 3 0 1 2 domains. Comparison of the STM and XPS data shows that only half the phenyl imides at the surface are imaged. Pi-stacking of the phenyl rings is proposed to account for this observation.