PNNL

Abstract

Photoelectron and Auger peaks are central to most of the important uses of X-ray photoelectron spectroscopy (XPS) and thus they receive the most attention in many types of analysis. Quantitative chemical analysis using XPS requires the assessment of the intensities of the photoemission peaks of the elements detected. Determination of peak intensities requires separation of the photoelectron peak signals from background on which the peaks rest. For determination of peak area intensities, the background is subtracted from the overall signal intensity. The spectral background is also critical when peak fitting is used to determine intensities of overlapping peaks and the model of background used in this process can impact the results. In addition to the impact on quantitative analysis, information about the depth distribution of elements in the near surface region can often be obtained by visual inspection of the background and quantified using appropriate modeling. This introductory guide provides some basic information about backgrounds in XPS analysis, describes the types of background models that are most commonly used, suggests some of their strengths and weaknesses and provides examples of their use and misuse. Although the fundamental nature of some components of the background signals in XPS are not understood, indicating that the none of the models in use are fully correct and the area is subject to active research, appropriate good practices have been established for most routine analysis. The guide will describe good practices and identify errors that frequently appear in the literature.