X-ray Photoelectron Spectroscopy or Electron Spectroscopy for Chemical Analysis
Highly sensitive surface elemental analysis with chemical state information
X-ray photoelectron spectroscopy (XPS) otherwise known as Electron Spectroscopy for Chemical Analysis (ESCA) is a method for identification of the elemental composition of the surface of a sample (20-50Å). Using a monochromatic X-ray beam, ESCA causes emission of core electrons. The kinetic energy of the emitted electrons is equal to the incident X-ray energy less the binding energy of the electron and the work function of the instrument.
The observed kinetic energy of the electrons is then related to the binding energy, which allows for element identification. Ejected electrons can escape only from a depth of approximately 3 nanometers or less, making electron spectroscopy most useful to study surfaces of solid materials. Detection limits, depending on the element, are generally on the order of ~0.2% atomic percent. ESCA detects all the elements except for H and He, and can also be used to characterize specific functional groups associated with a specific element.
- Information on surface chemical composition
- Shows chemical environment of the atom
- Oxidation analysis of a specimen (oxidation depth and oxidation state)