Editing Ion source (section)

==Electron ionization==
{{Main|Electron ionization}}
[[File:Schematic diagram of an EI ion source.jpg|thumb|300px|Electron ionization source schematic]]
[[Electron ionization]] is widely used in mass spectrometry, particularly for [[organic chemistry|organic]] molecules. The [[Phase (matter)|gas phase]] reaction producing electron ionization is

:<chem>M{} + e^- -> M^{+\bullet}{} + 2e^- </chem>

where M is the atom or molecule being ionized, <chem>e^-</chem> is the electron, and <chem>M^{+\bullet}</chem> is the resulting ion.

The electrons may be created by an [[arc discharge]] between a [[cathode]] and an [[anode]].

An electron beam ion source (EBIS) is used in [[atomic physics]] to produce highly charged [[ion]]s by bombarding [[atom]]s with a powerful [[electron beam]].<ref name="Brown2006">{{cite book|author=Ian G. Brown|title=The Physics and Technology of Ion Sources|url=https://books.google.com/books?id=cdjGzG_zBLwC|date=6 March 2006|publisher=John Wiley & Sons|isbn=978-3-527-60454-8}}</ref><ref name="BeyerBeyer1997">{{cite book|author1=Heinrich Beyer|author2=Heinrich F. Beyer|author3=H.-Jürgen Kluge|author4=H.-J. Kluge |author5=Vi͡acheslav Petrovich Shevelʹko |title=X-Ray Radiation of Highly Charged Ions|url=https://books.google.com/books?id=8_AJFBC2-BsC|date=14 August 1997|publisher=Springer Science & Business Media|isbn=978-3-540-63185-9}}</ref> Its principle of operation is shared by the [[electron beam ion trap]].

===Electron capture ionization===
Electron capture ionization (ECI) is the ionization of a gas phase [[atom]] or [[molecule]] by attachment of an [[electron]] to create an ion of the form A<sup>−•</sup>. The reaction is

:<chem>A + e^- ->[M] A^-</chem>

where the M over the arrow denotes that to conserve [[energy]] and [[momentum]] a third body is required (the [[molecularity]] of the reaction is three).

Electron capture can be used in conjunction with [[chemical ionization]].<ref>{{Citation | doi = 10.1021/ac50035a017 | title = Electron capture negative ion chemical ionization mass spectrometry | year = 1978 |author1=Donald F. Hunt |author2=Frank W. Crow | journal = Analytical Chemistry | volume = 50 | issue = 13 | pages = 1781–1784}}</ref>

An [[electron capture detector]] is used in some [[gas chromatography]] systems.<ref>{{GoldBookRef|title=electron capture detector (in gas chromatography)|file= E01981}}</ref>