Editing Ion source (section)

===Field desorption===
{{Main|Field desorption}}
[[File:Field desorption.gif|thumb|300px|Field desorption schematic]]
Field desorption refers to an ion source in which a high-potential electric field is applied to an emitter with a sharp surface, such as a razor blade, or more commonly, a filament from which tiny "whiskers" have formed.<ref>{{cite journal | last1 = Beckey | first1 = H.D. | date =1969 | title = Field ionization mass spectrometry |journal=Research/Development | volume = 20 | issue = 11| page = 26 }}</ref>  This results in a very high electric field which can result in ionization of gaseous molecules of the analyte.  Mass spectra produced by FI have little or no fragmentation.  They are dominated by molecular radical cations {{chem2|M^{+.} }} and less often, protonated molecules {{chem2|[M + H]+}}