Applications of auger electron spectroscopy in the chemical state analysis of copper and its oxides

Electron-induced Auger electron spectroscopy was successfully applied to differentiate copper species, such as metallic Cu, Cu 2 O, CuO, and Cu(OH) 2 . To do so, high-quality standard spectra were collected and their key parameters, including peak positions, widths, intensity ratios, and peak shapes, were examined to evaluate their effectiveness in chemical state identification. Average values and standard deviations were reported for each parameter. The results reveal sufficient spectral differences among Cu metal, Cu 2 O, CuO, and Cu(OH) 2 to enable chemical fingerprinting, though no single parameter provided information sufficient for accurate speciation. Instead, a combination of spectral features must be used to enable reliable identification of these species. This approach was successfully applied to identify the chemical states of oxide layers formed on two different copper samples. The results from the Auger analyses were consistent with those from XPS measurements. This methodology was also applied to determine the presence of Cu 2 O oxide inclusions in cold sprayed copper, and the results were consistent with previously published results from TEM, EELS, and electron diffraction studies. Compared to these techniques, Auger electron spectroscopy requires minimal sample preparation and offers high spatial and surface sensitivity.