Editing Ion source (section)

===Ion attachment===
{{Main|Ion-attachment mass spectrometry}}
[[Ion-attachment mass spectrometry|Ion-attachment ionization]] is similar to [[chemical ionization]] in which a cation is attached to the analyte molecule in a reactive collision:
:<chem>M + X+ + A -> MX+ + A</chem>

Where M is the analyte molecule, X<sup>+</sup> is the cation and A is a non-reacting collision partner.<ref>{{cite journal|title=Lithium ion attachment mass spectrometry: Instrumentation and features|journal=Review of Scientific Instruments|volume=72|issue=5|page=2248|bibcode=2001RScI...72.2248S|last1=Selvin|first1=P. Christopher|last2=Fujii|first2=Toshihiro|date=2001|doi=10.1063/1.1362439}}</ref>

In a radioactive ion source, a small piece of radioactive material, for instance <sup>63</sup>[[Nickel|Ni]] or <sup>241</sup>[[Americium|Am]], is used to ionize a gas.{{citation needed|date=July 2014}} This is used in ionization [[smoke detector]]s and [[ion mobility spectrometer]]s.