X-ray photoelectron spectroscopy (XPS) is an advanced microscopic analysis technology for electronic materials and components. XPS or ESCA is the abbreviation of X-ray as excitation light source.

XPS not only provides information on molecular structure and valence state for chemical research, but also provides information on elemental composition and content, chemical state, molecular structure and chemical bonds of various compounds for electronic materials research.

The energy of X-ray photons is between 1000 ~ 1500 ev, which can ionize valence electrons of molecules and excite internal electrons, and the energy level of internal electrons is little affected by molecular environment.

The internal electron binding energy of the same atom has little difference in different molecules, so it is characteristic. Photons incident on the solid surface excite photoelectrons, and the experimental technique of analyzing photoelectrons with an energy analyzer is called photoelectron spectroscopy.