"The mechanism by which an Auger electron is released starts with an electron being ejected by the primary electron beam from its shell, say, the K-shell. Another electron from an outer shell (say, the L1-level) of the same atom emits energy in the form of a photon in order to go down to the K-shell position vacated by the ejected electron. The photon released by the second electron will either get lost or eject yet another electron from a different level, say, L2. Auger electrons are electrons ejected in this manner, such as the third electron from L2 in the example.
Thus, the generation of an Auger electron requires at least three electrons, which in the example above are the K, L1, and L2 electrons. In this example, the emitted Auger electron is referred to as a KLL Auger electron. Hydrogen and Helium atoms have less than three electrons, and are therefore undetectable by AES."
Frederick
