Chloride uptake by oxide covered aluminum as determined by X-ray photoelectron and X-ray absorption spectroscopy

The uptake of chloride by aluminum polarized at potentials below (less posi tive than) the pitting potential in 0.1 M NaCl solutions was studied using X-ray photoelectron spectroscopy (XPS) and X-ray absorption spectroscopy (X AS). The XPS chloride spectra showed that-two distinct sets of doublets are present. One doublet is related to chloride on the surface and the second is related to chloride incorporated in the oxide film. In the case of XAS, deconvolution of the spectrum obtained for samples polarized below the pitt ing potential also showed the presence of chloride in the near surface regi on and in the oxide film. The important point of this work is that the obse rved chloride was present in two different chemical environments as determi ned with both XAS and XPS. (C) 1999 The Electrochemical Society. S0013-4651 (98)07-030-X. All rights reserved.