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The carbon 1s photoelectron spectrum is the most widely fit and analyzed narrow scan in the x-ray photoelectron spectroscopy (XPS) literature. It is, therefore, critically important to adopt well-established protocols based on best practices for its analysis, since results of these efforts affect research outcomes in a wide range of different application areas across materials science. Unfortunately, much XPS peak fitting in the scientific literature is inaccurate. In this guide, we describe and explain the most common problems associated with C 1s narrow scan analysis in the XPS literature. We then provide an overview of rules, principles, and considerations that, taken together, should guide the approach to the analysis of C 1s spectra. We propose that following this approach should result in (1) the avoidance of common problems and (2) the extraction of reliable, reproducible, and meaningful information from experimental data.

This study was undertaken to understand the extent and nature of problems in x-ray photoelectron spectroscopy (XPS) data reported in the literature. It first presents an assessment of the XPS data in three high-quality journals over a six-month period. This analysis of 409 publications showing XPS spectra provides insight into how XPS is being used, identifies the common mistakes or errors in XPS analysis, and reveals which elements are most commonly analyzed. More than 65% of the 409 papers showed fitting of XP spectra. An ad hoc group (herein identified as "the committee") of experienced XPS analysts reviewed these spectra and found that peak fitting was a common source of significant errors. The papers were ranked based on the perceived seriousness of the errors, which ranged from minor to major. Major errors, which, in the opinion of the ad hoc committee, can render the interpretation of the data meaningless, occurred when fitting protocols ignored underlying physics and chemistry or contained major errors in the analysis. Consistent with other materials analysis data, ca. 30% of the XPS data or analysis was identified as having major errors. Out of the publications with fitted spectra, ca. 40% had major errors. The most common elements analyzed by XPS in the papers sampled and researched at an online database, include carbon, oxygen, nitrogen, sulfur, and titanium. A scrutiny of the papers showing carbon and oxygen XPS spectra revealed the classes of materials being studied and the extent of problems in these analyses. As might be expected, C 1s and O 1s analyses are most often performed on sp2-type materials and inorganic oxides, respectively. These findings have helped focus a series of XPS guides and tutorials that deal with common analysis issues. The extent of problematic data is larger than the authors had expected. Quantification of the problem, examination of some of the common problem areas, and the development of targeted guides and tutorials may provide both the motivation and resources that enable the community to improve the overall quality and reliability of XPS analysis reported in the literature Refereed/Peer-reviewed

This guide deals with methods to control surface charging during XPS analysis of insulating samples and approaches to extracting useful binding energy information. The guide summarizes the causes of surface charging, how to recognize when it occurs, approaches to minimize charge buildup, and methods used to adjust or correct XPS photoelectron binding energies when charge control systems are used. There are multiple ways to control surface charge buildup during XPS measurements, and examples of systems on advanced XPS instruments are described. There is no single, simple, and foolproof way to extract binding energies on insulating material, but advantages and limitations of several approaches are described. Because of the variety of approaches and limitations of each, it is critical for researchers to accurately describe the procedures that have been applied in research reports and publications.

XPS is widely used to identify and quantify the elements present at the surface of polymeric materials. The energy distribution of photoelectrons emitted from these elements contains information about their chemical state, potentially allowing the analyst to identify and quantify specific functional groups. These functional groups may originate from the synthesis and processing of the polymers, from postsynthetic modifications such as surface grafting, or indeed may be unrelated to the polymer (additives and contaminants). Extracting reliable and meaningful information from XPS data is not trivial and relies on careful and appropriate experimentation, including experimental design, sample preparation, data collection, data processing, and data interpretation. Here, the authors outline some of these challenges when performing XPS analysis of polymers and provide practical examples to follow. This guide will cover all relevant aspects over the course of a typical experiment, including tips and considerations when designing the experiment, sample preparation, charge neutralization, x-ray induced sample damage, depth profiling, data analysis and interpretation, and, finally, reporting of results. Many of these topics are more widely applicable to insulating organic materials, and the recommendations of this guide will help to ensure that data is collected and interpreted using current best practices.