Biesinger, Mark C.; Payne, Brad P.; Grosvenor, Andrew P.; Lau, Leo W. M.; Gerson, Andrea R.; Smart, Roger St. C.

Applied Surface Science (2011), 257(7), 2717-2730 CODEN: ASUSEE; ISSN: 0169-4332. English.

Chem. state x-ray photoelectron spectroscopic anal. of 1st row transition metals and their oxides and hydroxides is challenging due to the complexity of their 2p spectra resulting from peak asymmetries, complex multiplet splitting, shake-up and plasmon loss structure, and uncertain, overlapping binding energies. The previous paper in which the authors examined Sc, Ti, V, Cu and Zn species, showed that all the values of the spectral fitting parameters for each specific species, i.e. binding energy (eV), full wide at half maximum (FWHM) value (eV) for each pass energy, spin-orbit splitting values and asym. peak shape fitting parameters, are not all normally provided in the literature and data bases, and are necessary for reproducible, quant. chem. state anal. A more consistent, practical and effective approach to curve fitting was developed based on a combination of (1) standard spectra from quality reference samples, (2) a survey of appropriate literature databases and/or a compilation of literature refs. and (3) specific literature refs. where fitting procedures are available. This paper extends this approach to the chem. states of Cr, Mn, Fe, Co and Ni metals, and various oxides and hydroxides where intense, complex multiplet splitting in many of the chem. states of these elements poses unique difficulties for chem. state anal. The curve fitting procedures proposed use the same criteria as proposed previously but with the addnl. complexity of fitting of multiplet split spectra which was done based on spectra of numerous reference materials and theor. XPS modeling of these transition metal species. Binding energies, FWHM values, asym. peak shape fitting parameters, multiplet peak separation and peak area percentages are presented. The procedures developed can be used to remove uncertainties in the anal. of surface states in nanoparticles, corrosion, catalysis and surface-engineered materials.