Photoelectron and infrared reflection absorption spectroscopy of benzotriazole adsorbed on copper and cuprous oxide surfaces

Abstract

The chemisorption of benzotriazole on clean copper and currous oxide surfaces has been investigated. In this study, we focus on the structural charaterization of the very first layers of differently deposited (evaporated in UHV or adsorbed from aqueous solution) benzotriazole, by combining X-ray photoelectron spectroscopy (XPS), ultraviolet photoelectron spectroscopy (UPS) and infrared reflection absorption spectroscopy (IRAS). Our XPS and UPS data show that the chemical structures of the differently prepared layers are almost identical. Conclusive evidence is obtained for coordination to the copper and cuprous oxide surfaces through the triazole-nitrogens, with a subsequent loss of the hydrogen bonded to the triazole ring. IRAS has been used to extract information about the orientational variations within the chemisorbed layers. The results from this analysis allow us to propose a new orientation for benzotriazole on copper, where the molecular plane of the adsorbate is tilted in relation to the metal surface. This orientation is consistent with the bonding information obtained by XPS and UPS.