Electron Capture Definition

Electron capture diagram
In one type of electron capture the nucleus absorbs the electron and an x-ray is released. In the Auger effect, the outer electron is ejected.

Pamputt, Wikimedia Commons

Electron capture is a type of radioactive decay where the nucleus of an atom absorbs a K or L shell electron and converts a proton into a neutron. This process reduces the atomic number by 1 and emits gamma radiation or an x-ray and a neutrino.
The decay scheme for electron capture is:
ZXA + e-ZYA-1 + ν + γ
where
Z is the atomic mass
A is atomic number
X is the parent element
Y is daughter element
e- is an electron
ν is a neutrino
γ is a gamma photon

Also Known As: EC, K-capture (if K shell electron is captured), L-capture (if L shell electron is captured)

Example

Nitrogen-13 decays to Carbon-13 by electron capture.
13N7 + e-13C6 + ν + γ

History

Gian-Carlo Wick proposed the theory of electron capture in 1934. Luis Alvarez was the first to observe K-electron capture in the isotope vanadium-48. Alvarez reported his observation in Physical Review in 1937.