XPS (X-ray photoelectron spectroscopy)

X-ray photoelectron spectroscopy (XPS) is a quantitative spectroscopic technique that measures elemental composition, empirical formula, chemical state and electronic state of the elements that exist within a material.

XPS spectra are obtained by irradiating a material with a beam of X-rays while simultaneously measuring the kinetic energy and number of electrons that escape from the top 1 to 12 nm of the material being analyzed. XPS requires ultra-high vacuum (UHV) conditions.