Practical guide to the use of backgrounds in quantitative XPS

Abstract

This guide is intended for both the novice in x-ray photoelectron spectroscopy (XPS) as well as users with some experience. XPS is one of the most widely used methods to characterize surface nanostructured samples, and XPS is now also commonly accessible to most material scientists through XPS facility centers. It is, therefore, increasingly used as a routine analysis technique to complement other techniques. This has led to an increase in the number of users who may not have a full understanding of the details of XPS and consequently must rely on the report provided by the XPS center. The purpose of this practical guide on the aspects of quantitative XPS is first to put the reader in a position to be able to understand and judge the meaning and possible errors in atomic concentrations based on analysis of peak intensities, which is the standard way quantitative XPS is reported. We discuss different ways to improve the analysis. This is attained by giving the reader a good understanding of how the intensities in the peak and the background of inelastically scattered electrons are linked together through the depth distribution of atoms. We then explore how this can be applied to greatly increase the capabilities of XPS to more accurately determine the composition and structure of surfaces on the nanoscale. This is possible at different levels of sophistication. We first see how a visual inspection of the XPS survey spectrum can be applied to get a quick rough indication of the structure. Next, we go through other more quantitative methods that are being used. The practical application of these techniques is illustrated by several examples.

Improved depth information from routine analysis of the inelastic background of XPS and HAXPES spectra using optimized two‐ and three‐parameter cross‐sections

“…These higher photon energies result in photoelectrons with substantially larger inelastic mean free paths (IMFP or λ ) and thereby larger probing depths. It is well established that quantification based on XPS peak areas can be highly inaccurate 1 because of the peak attenuation factor that varies strongly with the atom depth distribution. This can be solved by including in the analysis, the background of inelastically scattered electrons, which is always seen on the low kinetic energy side of XPS peaks.…”

Pyrene-Based Fluorescent Porous Organic Polymers for Recognition and Detection of Pesticides

“…With the increase of analyte concentration, the fluorescence quenching effect of the LNUs became more obvious and quenched completely ( Figure 5 a–d). In order to better explain this phenomenon, X-ray photoelectron spectroscopy (XPS) was used to calculate the relative content of each element (C, N, F, Cl) corresponding to the amount of pesticide adsorbed into the POP architecture [ 39 , 40 , 41 , 42 , 43 , 44 , 45 ]. As shown in Figure S7 , the adsorption uptakes were calculated to be 116.0 mg g −1 (NF-adsorbed LNU-45), 70.0 mg g −1 (CTL-adsorbed LNU-45), 139.8 mg g −1 (DCN-adsorbed LNU-45), and 231.9 mg g −1 (TFL-adsorbed LNU-45).…”

High-order replica bands in monolayer FeSe/SrTiO3 revealed by polarization-dependent photoemission spectroscopy

“…2c . The Tougaard background considers the inelastic scattering of the electrons, and is widely used in photoemission spectroscopy 36 , 37 . The spectral lineshape after background subtraction is nicely fit to a principal peak along with three replica peaks that follow the relation in Eq.…”