Segregation in CuPd Alloys Studied by X-ray Photoelectron Spectroscopy Using Lineshape Analysis by the Fuzzy k-Nearest Neighbour Rule

The surface segregation process in polycrystalline Cu75Pd25 alloy is investigated. Quantitative and qualitative analyses of selected CuPd alloys with atomic composition Cu25Pd75, Cu50Pd50 and Cu75Pd25 are based on the multiline (ML) approach and the spectra lineshape analysis with the use of a statistical pattern recognition method, called the fuzzy k-nearest neighbour rule (fkNN). The analyzed X-ray photoelectron spectra (XPS), recorded using AlK alfa radiation from 280 eV to 1450 eV, exhibit a varying mean escape depth depending on the investigated photoelectron kinetic energy. The lineshape analysis, allowing to identify qualitatively and quantitatively the atomic composition and structure within the selected electron sampling depth, was shown to be consistent with the results of conventional quantitative analyses, based on measured binding energy shifts and intensities, and applicable for the layer segregation processes.