Auger effect

Article By:

Feldman, Leonard C. AT&T Bell Laboratories, Murray Hill, New Jersey.

Last reviewed:October 2019

DOI:https://doi.org/10.1036/1097-8542.062300

One of the two principal processes for the relaxation of an inner-shell electron vacancy in an excited or ionized atom. The Auger effect is a two-electron process in which an electron makes a discrete transition from a less bound shell to the vacant, but more tightly bound, electron shell. The energy gained in this process is transferred, via the electrostatic interaction, to another bound electron which then escapes from the atom. This outgoing electron is referred to as an Auger electron and is labeled by letters corresponding to the atomic shells involved in the process. For example, a KL_I L_III Auger electron corresponds to a process in which an L_I electron makes a transition to the K shell and the energy is transferred to an L_I electron (illus.a). By the conservation of energy, the Auger electron kinetic energy E is given by E = E(K) − E(L_I) − E(L_III) where E(K,L) is the binding energy of the various electron shells. Since the energy levels of atoms are discrete and well understood, the Auger energy is a signature of the emitting atom. See also: Electron configuration; Energy level (quantum mechanics)

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