MECHANISM OF COPPER PASSIVATION IN AQUEOUS SODIUM CARBONATE-BICARBONATE SOLUTION DERIVED FROM COMBINED X-RAY PHOTOELECTRON SPECTROSCOPIC AND ELECTROCHEMICAL DATA

X-ray photoelectron spectroscopy (XPS) was used to characterize the pa ssivating films anodically formed on copper in NaHCO3 and Na2CO3 aqueo us solutions (9-11 pH range). The influence of potential and solution pH on the composition and protective characteristics of the passivatin g layers was considered. The analysis of the experimental data support s the composed nature of the formed films. Direct evidence regarding t he addition of carbonate species to the surface layers in potential ra nges positive to the onset of Cu(II) oxides formation was achieved fro m XPS data. Specific components of the XPS signals attributable to car bonate species present in the passivating films could be identified.