Comparison of validity and consistency of methods for quantitative XPS peak analysis

Abstract

In the present work, we have tested the consistency and validity of the Tougaard, Shirley and straight-line methods for determination of peak intensities in XPS. Intensities were determined from essentially all photoelectron peaks (with Mg K a and A1 K a radiation) from seven polycrystalline elemental solids (Co, Ni, Cu, Zn, Ag, Pt and Au) and for three sets of polycrystalline alloys (Cuo.7,Auo.,, , Cu,., Au,., , Cu,.,, Au0.75, and Coo~,sNio~2,, Co,~,Nio~, , Coo.4,Nio.,,, Coo.2sNio.,s and Cuo.ssNio.44Mno~o,). For the three methods, the consistency of the peak intensity ratios determined under a variation of analyser settings was' studied. The validity of the three methods was studied by comparison of peak intensity ratios to two sets of theoretical photoionization cross-sections (due to Scofield and Band et id., respectively). The inelastic electron mean free paths were taken from theoretical tabulations when available or from analytical expressions (both due to Tanuma et d . ) .The Tougaard method is found to be superior to the Shirley and straight-line methods, both with respect to consistency and validity. For a selected set of peaks where the error on theory is minimal, the deviation from theory is 3% for the Tougaard method and 3340% for the Shirley and straight-line methods. Considering all XPS peaks from seven metals, the root-mean-square deviation from theory for the Tougaard method is found to be -11% for the ratios of peak intensities to a peak from the same solid and -14% for the ratios of peak intensities to the Au 4d peak intensity. These deviations fall within the expected accuracy of theory. The corresponding root-meansquare deviations from theory for the Shirley and straight-line methods are found to be %YO and 25%, respectively.For alloys, the Tougaard method gives the most consistent description of the shake-up electrons. For the Shirley and straight-line methods applied to spin-orbit doublet peaks, the accuracy is in general worse than the above.

Preparation and properties of clean Si3N4 surfaces

“…A two-parameter scattering function was used with B ¼ 2704 eV 2 and C ¼ 1634 eV 2 (see Refs. [74,75]). The data in (b) have also been corrected for the 1/E dependence of the CMA étendue (see text) in constant-resolution mode.…”

“…Fig. 9 shows the data before and after application of the Tougaard [74,75] procedure for removing the background due to inelastically-scattered electrons, which is necessary for an accurate determination of peak areas. As part of this procedure, the spectrum in Fig.…”

Experimental Determination of the N 1s/C 1s Relative Sensitivity Factor for XPS

“…7,8 The energy ranges for background subtraction were selected to include shake-up satellites and plasmon peak.…”

Charge transfer effects on the chemical reactivity of PdxCu1−xnanoalloys

“…The Pd 3d and Cu 2p regions were measured using 30 eV pass energy and an energy step of 0.1 eV. 26 During the data fitting, the FWHM of metaloxygen and metal-metal components, as well as the binding energy of metal-oxygen components, were fixed for all samples.…”