#Asymmetric xps peak how to#

This is noted because the modern XPS systems have Hardware-Software Application Unit, allowing to process the XPS data вЂњon-the-flyвЂќ and, depending on the mainframe approach, the prescision quality of the final outcome will be strongly affected. In addition to mentioned above instrumental reasons, the shape of so-called вЂњXPSsynthetic peakвЂќ is also influenced by the choice of XPS Background Algorithm used to remove it. Influence of Asymmetry in XPS line-shapes

Let now have a look what type of XPS-function forms and approaches can be used in order to achieve the вЂњstate-of-theartвЂќ data processing.Дў. Also Poisson-character procedure might be employed for the state-of-the-art XPS Data Processing. In the case of an adaptive mainframe, one might mostly apply much wider possibilities for XPS Data Processing, because a set of XPS-functions are constructed, combined and applied within the iterative procedures of line-shape fitting. As it will be shown below, this is not the case for the active approach. And, at least, more iterations are needed for the static method of BG-modeling. When employing an admixture of the Gaussian-Lorentzian function-form to fit XPS line-shapes, one might also face with the fact that fitted FWHM will be essentially dependent on the fitting energy range when the static mainframe is employed. This problem might be even more serious for an asymmetric line-shapes of metal-like or metal-doped materials, for which the high Binding Energy tail of XPS core-level spectrum prolongs essentially. Perhaps we might not be original with our view, but the key weakness of static approach usually arises in underestimation of XPS line-shape area fitting, making it not always acceptable for XPS quantification. This is the most glaring contrast between these mainframe approaches, which are still the subject of discussions what is better to employ. At present, the following mainframe approaches can be recognized: static, when the XPS BG is subtracted prior to XPS line-shape fitting, and active, where the intensity of BG signal and the XPS line-shape will be adaptively determined during fitting. For example, if the background on the right (low-binding energy side) shows a non-negligible slope, it is necessary to fit a straight line in that region and subtract the extrapolated line to the whole spectrum. Reasons), it is the need to perform reasonable вЂњad-hocвЂќ corrections of the XPS-data before applying line-shape fitting. strong XPS signal interference because of the external It is known, that in some special experimental cases (i.e. This set of backgrounds appears due to the reason, that quantifying the intensity and shape of XPS-peaks requires precise or, so-called вЂњstate-of-the-artвЂќ processing of BG-signal. Well known that for XPS line-shape processing the following types of background may be employed: linear, exponential, polynomial, Tougaard and Shirley. for nonmonochromatized x-ray sources or for contaminated metal-anodes (targets) at X-ray Source Tube ). The actual origin of the X-ray source (in most cases theory is predicting an asymmetry of XPS spectrum, i.e. Transmitting function of the concrete XPS electron analyzer (admixture of asymmetric contribution) 2. Instrumental reasons: XPS apparatus influence 1. Differential surface charging of the sample under XPS-study. Core-hole life-time broadening (Coster-Kronig processes, вЂ¦ ) XPS Final-states effects 1. While performing an XPS analysis, in most common cases one can realize, that the recorded XPS spectra are exhibiting clear deviations from the idealized symmetric shapes and this may happen due to the following effects: Material-under-study reasons: Effects of intrinsic origin 1.

This was demonstrated using theoretical considerations. In the case of metallike samples or metal-doped materials under XPS study, it has been shown, that asymmetric spectra profiles have to be expected. Introduction A range of physically possible line-shapes in core-level XPS is relatively wide, and in most cases, unfortunately, simple Gaussian or Lorentzian functions or even their combinations are very rarely adequate to describe particular situation. Zatsepin) Scientific edition made by Prof.

#Asymmetric xps peak how to#