Electronic structure of copper films in aqueous solutions: in-situ x-ray spectroscopic study
Butorin, S. M.1; Kvashnina, K. O.1; Modin, A.1; Soroka, I.1; Marsellini, M.1; Guo, J.-H.2; Werme, L.1; Nordgren, E. J.1 1Sweden; 2United States
Possibility of using x-ray absorption spectroscopy (XAS) and resonant inelastic x-ray scattering (RIXS) to probe the Cu oxidation state and changes in the electronic structure during interaction between copper and groundwater solutions were examined. Surface modifications induced by chemical reactions of oxidized Cu films with Cl−, SO42− and HCO3− ions in aqueous solutions with various concentrations were studied in-situ using liquid cells. Copper corrosion processes in groundwater were monitored up to 9 days. By comparing Cu 2p - 3d, 4s transitions for a number of reference substances previously measured, electronic structure changes of the Cu films were analyzed. The XAS and RIXS spectral shape at the Cu edge, the chemical shift of the main line for Cu2+, and the energy positions of the observed satellites served as a tool for monitoring the changes during the reaction. It was found that the pH value and the Cl concentration in solutions strongly affect the speed of the corrosion reaction.