Electron emitted from an core-ionised atom via a two step process. Generally an ionised atom will emit light, when an electron
fills the empty place, but under certain conditions the energy will be transferred onto another electron which is emitted with a characteristic energy. This is a competing process to x-ray
emissions and can be observed for lighter atoms
predominantly. Auger electrons
are named after the three atomic shells involved (e.g. KLM).