Chapter 4.3.1 - X-ray photoelectron spectroscopy

Abstract

The use of X-ray photoelectron spectroscopy (XPS) for the analysis of nanoparticles is described. The method has been extensively used to identify elements, their chemical state, and their concentration at surfaces for many years. It is the most accurate method for measuring the composition and thickness of thin (<10nm) surface coatings. The information depth of the method arises from the small distance that electrons can travel through materials without losing energy and these dimensions are similar to those of importance in nanoparticle analysis. This chapter provides an overview of the physical principles of XPS, the instrumentation, and the methods to interpret the data. That interpretation depends upon prior knowledge, or inference, of the physical structure of the sample. Therefore, for nanomaterials, XPS is best used in combination with other methods that are capable of measuring particle size and particle shape. Due to the importance of surfaces in the performance, toxicity, and behaviour of nanoparticles, XPS is an important technique to ensure that particles are completely characterized.