Auger effect is discovered by P. Auger in 1925. When the electron beam is irradiated on the sample, vacancies can be created in the electron level in the sample atom. This state is unstable and the sample emits a fluorescent X-ray as it tends to stabilize, allowing one electron to escape to the vacancy while the other electron escapes into free space. This escaping electron is called Auger electron.
The energy of an Auger electron movement is independent of the energy of the irradiated electron beam and depends on the intrinsic energy of the material. Therefore, the energy spectrum of Auger electrons escaping from the material can be analyzed structurally.
The irradiation source of auger electron spectroscopy (AES) usually uses a 2k ~ 10keV electron beam. The energy range of auger electron kinetic is 0 ~ 1keV. In addition to Auger electrons, there are other kinds of electrons with the same kinetic energy based on secondary electron emission in this energy range. Therefore, not only to measure the energy of the electron, but also to measure the increase or decrease of the electron due to the Auger electron.