X-Ray Photoelectron Spectroscopy

Abstract Clays and clay minerals interact with the surrounding environment through their surfaces. Their surface chemical compositions can differ from the bulk or average compositions because of chemical reactions such as adsorption, dissolution, and oxidation at the surfaces. Accordingly, analytical information on surface layers is important for a better understanding of the geochemical processes involving clay minerals. The recent development of surface-analytical techniques has enabled us to probe the surface chemistry of geological solid samples with complex composition. Among the many surface-analytical techniques, X-ray photoelectron spectroscopy (XPS) is commonly used in a variety of fields, including earth and environmental sciences, due to its versatility. This chapter demonstrates some examples of important items of information (surface chemical composition and chemical-bonding state of constituent elements) that can be obtained by applying XPS to clay minerals and related minerals.