Understanding the initial stages of polymer grafting on metals: a photoelectron spectroscopy study of acrylonitrile adsorption on transition metal surfaces

X-ray and UV photoelectron spectroscopies show that acrylonitrile is chemis orbed on iron, nickel and copper polycrystalline surfaces via the carbon an d nitrogen atoms. Depending on the conditions used, different adsorption ge ometries are found. The molecules can either be adsorbed flat on the surfac e and chemically bound by a (2p(pi))-(3d/4s) overlap via both the C=C doubl e bond and the C dropN nitrile group or they can be adsorbed perpendicular to the surface via a covalent interaction between the nitrogen lone pair an d the 3d-4s levels of the metals. Analysis of the XPS data obtained on mole cular mono-layers chemisorbed on metal surfaces emphasizes the importance o f initial-state effects (charge transfer upon chemisorption, contribution o f the metal surface dipole) and final-state effects (metal screening and po larization effect within the mono-layer). The correlation between the XPS a nd UPS data illustrates the importance of the metal surface dipole in under standing the workfunction changes upon molecular adsorption on metal surfac es. (C) 2001 Elsevier Science BY All rig ts reserved.