Quantitative surface characterization using X-ray photoelectron spectroscopy

Use of X-ray Photoelectron Spectroscopy (XPS) for quantitative surface analysis is reviewed. Examples chosen are from our research on heterogeneous catalysts. XPS is useful for measuring distributions of oxidation states because of significant chemical shifts for many elements. However, linewidths complicate analysis of mixtures, necessitating the use of data analysis methodology. Use of factor analysis or deconvolution with non-linear least squares curve fitting gives useful protocols. Five important questions are posed, and some examples of solutions are presented: 1) How many components are present? 2) Where are they located? 3) What do they look like? 4) How much of each component is present? 5) How good is the answer?