XPS, or X-ray Photoelectron Spectroscopy, is an analytical technique used to study the surface chemistry of materials. It works by irradiating a sample with X-rays, which causes the emission of photoelectrons. By measuring the kinetic energy of these electrons, researchers can determine the elemental composition and chemical state of the surface. This method is widely used in various fields, including materials science, nanotechnology, and semiconductor research. XPS provides valuable insights into the properties of materials, helping scientists understand how different elements interact and how surface treatments affect performance.