Essential principles and practices in x-ray photoelectron spectroscopy

X-ray photoelectron spectroscopy (XPS) is a widely used technique for the chemical analysis of solid surfaces, sensitive to the chemical environments of atoms via core-level binding energy shifts. While modern instruments allow experimental data to be acquired with ease, their evaluation and interpretation remain challenging for newcomers to the field, as a profound knowledge of the method is required for correct analysis. Here, we present a concise yet comprehensive overview of the fundamental principles and methodologies of XPS, covering photoemission processes, chemical shifts, charge referencing, peak fitting, and quantification strategies. This overview aims to bridge the gap between data collection and reliable analysis, providing essential knowledge for correct interpretation. By clarifying key concepts and common practices, this work supports improved accuracy in surface chemical characterization using XPS.