Editing Electron capture (section)

==Reaction details==
[[File:Electron-capture.svg|alt=Leading-order EC Feynman diagrams|thumb|309x309px|The leading-order [[Feynman diagram]]s for electron capture decay. An [[electron]] interacts with an [[up quark]] in the nucleus via a [[W and Z bosons|W boson]] to create a [[down quark]] and [[electron neutrino]]. Two diagrams comprise the leading (second) order, though as a [[virtual particle]], the type (and charge) of the W-boson is indistinguishable.]]
The electron that is captured is one of the atom's own electrons, and not a new, incoming electron, as might be suggested by the way the reactions are written below. A few examples of electron capture are:
:{|
|-
| {{math| {{nuclide|link=yes|aluminium|26}} &nbsp; }}
| {{math| + &nbsp; {{SubatomicParticle|link=yes|Electron}} &nbsp; &nbsp; → &nbsp; &thinsp; &nbsp; }}
| {{math| {{nuclide|link=yes|magnesium|26}} &nbsp; }}
| {{math| + &nbsp; {{SubatomicParticle|link=yes|Electron Neutrino}} }}
|-
| {{math| {{nuclide|link=yes|nickel|59}} &nbsp; }}
| {{math| + &nbsp; {{SubatomicParticle|link=yes|Electron}} &nbsp; &nbsp; → &nbsp; &thinsp; &nbsp; }}
| {{math| {{nuclide|link=yes|cobalt|59}} &nbsp; }}
| {{math| + &nbsp; {{SubatomicParticle|link=yes|Electron Neutrino}} }}
|-
| {{math| {{nuclide|link=yes|potassium|40}} &nbsp; }}
| {{math| + &nbsp; {{SubatomicParticle|link=yes|Electron}} &nbsp; &nbsp; → &nbsp;  &thinsp; &nbsp; }}
| {{math| {{nuclide|link=yes|argon|40}} &nbsp; }}
| {{math| + &nbsp; {{SubatomicParticle|link=yes|Electron Neutrino}} }}
|}

Radioactive isotopes that decay by pure electron capture can be inhibited from radioactive decay if they are fully [[ion]]ized ("stripped" is sometimes used to describe such ions). It is hypothesized that such elements, if formed by the [[r-process]] in exploding [[supernova]]e, are ejected fully ionized and so do not undergo radioactive decay as long as they do not encounter electrons in outer space. Anomalies in elemental distributions are thought{{By whom|date=September 2012}} to be partly a result of this effect on electron capture. Inverse decays can also be induced by full ionisation; for instance, {{SimpleNuclide|link=yes|Holmium|163}} decays into {{SimpleNuclide|link=yes|Dysprosium|163}} by electron capture; however, a fully ionised {{SimpleNuclide|Dysprosium|163}} decays into a bound state of {{SimpleNuclide|Holmium|163}} by the process of [[bound-state β− decay|bound-state β<sup>−</sup> decay]].<ref>{{cite journal
 |author-first=Fritz |author-last=Bosch
 |year=1995
 |title=Manipulation of Nuclear Lifetimes in Storage Rings
 |journal=Physica Scripta
 |volume=T59  |pages=221–229
 |doi=10.1088/0031-8949/1995/t59/030 |bibcode=1995PhST...59..221B
 |s2cid=250860726
 |url=http://www.ca.infn.it/~oldeman/resneu/physscr5_T59_030.pdf
 |url-status=dead
 |archive-url=https://web.archive.org/web/20131226210737/http://www.ca.infn.it/~oldeman/resneu/physscr5_T59_030.pdf
 |archive-date=2013-12-26
}}</ref>

[[Chemical bond]]s can also affect the rate of electron capture to a small degree (in general, less than 1%) depending on the proximity of electrons to the nucleus. For example, in <sup>7</sup>Be, a difference of 0.9% has been observed between half-lives in metallic and insulating environments.<ref>{{cite journal
 |author1-first=B. |author1-last=Wang
 |display-authors=etal
 |year=2006
 |title=Change of the <sup>7</sup>Be electron capture half-life in metallic environments
 |journal=The European Physical Journal A
 |volume=28 |issue=3
 |pages=375–377
 |bibcode = 2006EPJA...28..375W
 |doi = 10.1140/epja/i2006-10068-x  <!-- prior author/editor noted "subscription required" but no URL -->
|s2cid=121883028
 }}</ref> This relatively large effect is because beryllium is a small atom that employs valence electrons that are close to the nucleus, and also in orbitals with no orbital angular momentum. Electrons in '''s''' orbitals (regardless of shell or primary quantum number), have a probability antinode at the nucleus, and are thus far more subject to electron capture than '''p''' or '''d''' electrons, which have a probability node at the nucleus.

Around the elements in the middle of the [[periodic table]], isotopes that are lighter than stable isotopes of the same element tend to decay through electron capture, while isotopes heavier than the stable ones decay by [[electron emission]]. Electron capture happens most often in the heavier neutron-deficient elements where the mass change is smallest and positron emission is not always possible. When the loss of mass in a nuclear reaction is greater than zero but less than {{math|2''m''<sub>e</sub>''c''<sup>2</sup>}}  the process cannot occur by positron emission, but occurs spontaneously for electron capture.