APPLICATION OF X-RAY-ABSORPTION SPECTROSCOPY TO THE STRUCTURAL CHARACTERIZATION OF MONODISPERSED BENZOTRIAZOLE COATINGS ON PARTLY OXIDIZED COPPER THIN-FILMS

X-Ray absorption spectroscopy using synchrotron radiation has been use d to probe the structure of Copper-benzotriazole complexes and that of the benzotriazole involved in surface films following adsorption onto partly oxidised Cu thin films. Data recorded at the Cu-K edge and, us ing 4- and 5-bromo-substituted benzotriazole, at the Br-K edge are con sistent with the Cu(I) atoms coordinated to three or four benzotriazol e molecules through the N(2) position on the triazole ring. Examinatio n of the thin films using glancing-angle geometry suggests the adsorbe d film to be only a few monolayers in thickness with the benzotriazole molecules coordinated to Cu(I) ions in the oxidised Cu surface formin g a hydrogen-bonded surface complex similar, in part, to that proposed by Fang et al. (Surf. Sci., 1986, 176, 476). At the interface the sur face reaction appears to involve a topotactic arrangement with the (10 0) plane of Cu2O where the in-plane Cu-Cu interatomic distances closel y match that expected for the surface complex. The overall limitations of the glancing-angle technique to the characterisation of this kind of interfacial system are discussed.