X-ray Photoelectron Spectroscopy and Its Application for Corrosion Research

The electrochemical reactions that take place during metal corrosion usually lead to the formation of corrosion product layers on the metal surface. Conventional electrochemical methods characterize the qualitative properties of these layers, such as how they influence the kinetics and mechanism of the corrosion. However, determination of the actual chemical composition of the layer will explain the chemistry of the corrosion process, more clearly, and provide an adequate understanding of how the metal interacts with the corrosion environment. X-ray photoelectron spectroscopy (XPS) provides the corrosion analyst with this advantage. The method involves bombarding the metal surface with X-ray photons that have energy high enough to dislodge core-level electrons. The binding energy (and intensity) of the dislodged electrons can be utilized to identify the chemical species and their 396concentration present in the corrosion layer. The principles, instrumentation, and application of the XPS to corrosion research is discussed in this chapter.