The Auger effect

Source abstract

Abstract An atom ionized in an inner shell (for definiteness suppose the K shell) may return to state of lower energy by two distinct types of transition, viz., (1) by a transition of an electron from an outer shell to the K shell with the emission of a K series quantum of radiation; or (2) by a radiationless transition in which an outer electron falls to the K shell and gives up its surplus energy to another electron which is ejected from the atom. Convincing evidence of the occurrence of transitions of the second type in forthcoming from the work of many experimenters, particularly that of Auger and such a transition is referred to as an Auger transition. The same effect would result if the electron that falls to the K shell were considered to give rise to a K series quantum which is then absorbed photo-electrically in the shell of the ejected electron. For this reason the process may be referred to as the internal conversion of X-rays and the ratio of the number of Auger electrons ejected per unit time from a group of atom to the number ionized per unit time by some external agency may be referred to as the internal conversion coefficient. The magnitude of this coefficient has been studied experimentally by many workers, but no calculations have so far been made of the value predicted by quantum mechanics. Theory The general theoretical method to be used is similar to that applicable to the internal conversion of γ-rays, and the problem is considered specifically in Mott and Massey "Theory of Atomic Collisions," p. 264.