Photoreduction of Hexavalent Chromium during X‐Ray Photoelectron Spectroscopy Analysis of Electrochemical and Thermal Films

Cr spectra obtained by x‐ray photoelectron spectroscopy (XPS) of corrosion product layers is critically examined for evidence of photoreduction of hexavalent species. Tetravalent and trivalent decomposition products are identified, and methods of curve fitting and analysis are discussed. Disagreement between x‐ray absorption near end structure and XPS data, and between thermodynamic analysis and XPS data lead to the acceptance of a model for photoreduction of Cr6+based primarily upon core photoemission.