Editing Internal conversion (section)

{{Short description|Process where an excited nucleus ejects an orbital electron from its atom}}
{{About|the atomic nuclear process|the chemical process|Internal conversion (chemistry)}}
{{Nuclear physics}}
'''Internal conversion''' is an atomic decay process where an excited [[atomic nucleus|nucleus]] interacts [[electromagnetism|electromagnetically]] with one of the [[Atomic orbital|orbital electrons]] of an atom. This causes the electron to be emitted (ejected) from the atom.<ref name=Loveland>{{cite book|last=Loveland|first=Walter D.|title=Modern Nuclear Chemistry|year=2005|publisher=Wiley|isbn=0471115320|pages=232|url=https://books.google.com/books?id=ZAHJkrJlwbYC&q=internal+conversion&pg=PA233}}</ref><ref>M.E. Rose: "Theory of Internal Conversion", in:  Alpha-, Beta- and Gamma-Ray Spectroscopy, ed. by Kai Siegbahn, North-Holland Publishing, Amsterdam (1966), Vol. 2</ref> Thus, in internal conversion (often abbreviated IC), a high-energy electron is emitted from the excited atom, but not from the nucleus. For this reason, the high-speed electrons resulting from internal conversion are not called [[beta particle]]s, since the latter come from [[beta decay]], where they are newly created in the nuclear decay process.

IC is possible whenever [[gamma decay]] is possible, except if the atom is fully [[ionized]]. In IC, the [[atomic number]] does not change, and thus there is no transmutation of one element to another. Also, [[neutrinos]] and the [[weak force]] are not involved in IC.

Since an electron is lost from the atom, a hole appears in an electron aura which is subsequently filled by other electrons that descend to the empty, yet lower energy level, and in the process emit [[characteristic X-ray]](s), [[Auger electron]](s), or both. The atom thus emits high-energy electrons and X-ray photons, none of which originate in that nucleus. The atom supplies the energy needed to eject the electron, which in turn causes the latter events and the other emissions.

Since primary electrons from IC carry a fixed (large) part of the characteristic decay energy, they have a discrete energy spectrum, rather than the spread (continuous) spectrum characteristic of [[beta particle]]s. Whereas the energy spectrum of beta particles plots as a broad hump, the energy spectrum of internally converted electrons plots as a single sharp peak (see example below).