X-ray Photoelectron Spectroscopy

A surface-sensitive quantitative spectroscopic method based on the photoelectric effect called X-ray photoelectron spectroscopy XPS can identify the elements present in a material its elemental composition or that are present on its surface, as well as their chemical state, general electronic structure, and density of the electronic states in the material. Because it reveals both the elements that are present and the other elements to which they are linked, XPS is a strong measuring tool. The method may be applied to depth profiling when combined with ion-beam etching or to line profiling of the elemental composition throughout the surface. It is frequently used to examine chemical processes in materials in their raw form or after cleaving, scraping, being exposed to heat, reactive gases, or other physical or chemical changes. The photoemission spectroscopy technique known as XPS uses an X-ray beam to irradiate a material in order to produce electron population spectra. When the kinetic energy and the quantity of ejected electrons are measured, chemical states can be deduced. XPS needs high vacuum residual gas pressure p 106 Pa or ultra-high vacuum p 107 Pa conditions, while ambient-pressure XPS, in which materials are evaluated at pressures of a few tens of millibar, is now under development.