Our work has shown that all the values of the spectral fitting parameters for each specific species, i.e. binding energy (eV), full width at half maximum (FWHM) value (eV) for each pass energy, spin-orbit splitting values and asymmetric peak shape fitting parameters, are not all normally provided in the literature and databases, and are necessary for reproducible, quantitative chemical state analysis.
We have worked toward a consistent, practical, and effective approach to curve fitting 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 references, 3) specific literature references where fitting procedures are available and 4) theoretical fittings, where available, of multiplet split reference spectra. The use of well characterized standard samples and fitting of the entire peak shape has been shown to increase our ability to accurately identify and (semi) quantify the various species present in mixed oxide/hydroxide systems [1,2]. Additional chemical information has also been elucidated from Auger parameters and by using Wagner plots for compounds of Ni, Cu, Ga, In, Cd, and Zn. The unique spectral shapes of the LMM Auger peaks for these transition metals, particularly for Cu [3], as well as for Zn, In and Cd, have also been shown to be of use for chemical speciation. These methods have been shown to be effective in a wide variety of applications. Additionally, a recent assessment [4] of available charge corrections procedures for insulating samples will also be shown including recent work on defining the nature of adventitious carbon and improving its merit for charge correction usage [5].
Selected references
- M.C. Biesinger, L.W.M. Lau, A.R. Gerson, R.St.C. Smart, Applied Surface Science 257 (2010) 887.
- M.C. Biesinger, B.P. Payne, A.P. Grosvenor, L.W.M. Lau, A.R. Gerson, R.St.C. Smart, Applied Surface Science 257 (2011) 2717.
- M.C. Biesinger, Surface and Interface Analysis 49 (2017) 1325.
- M.C. Biesinger, Applied Surface Science 597 (2022) 15381.
- L.H. Grey, H.-Y. Nie, M.C. Biesinger, Applied Surface Science 653 (2024) 159319.