Editing Ion source (section)

===Electrospray ionization===
{{Main|Electrospray ionization}}
In electrospray ionization, a liquid is pushed through a very small, charged and usually metal, [[capillary]].<ref>{{cite journal | doi = 10.1002/mas.1280090103 |author1=Fenn, J. B. |author2=Mann, M. |author3=Meng, C. K. |author4=Wong, S. F. |author5=Whitehouse, C. M. | title = Electrospray Ionization-Principles and Practice | journal = [[Mass Spectrometry Reviews]] | date = 1990 | volume = 9 | issue = 1 | pages = 37–70|bibcode = 1990MSRv....9...37F }}</ref> This liquid contains the substance to be studied, the [[analyte]], dissolved in a large amount of [[solvent]], which is usually much more [[Volatility (chemistry)|volatile]] than the analyte. Volatile acids, bases or buffers are often added to this solution as well. The analyte exists as an [[ion]] in solution either in its anion or cation form. Because like charges repel, the liquid pushes itself out of the capillary and forms an aerosol, a mist of small droplets about 10 [[micro-|μm]] across. The aerosol is at least partially produced by a process involving the formation of a [[Taylor cone]] and a jet from the tip of this cone. An uncharged carrier gas such as [[nitrogen]] is sometimes used to help [[nebulizer|nebulize]] the liquid and to help evaporate the neutral solvent in the droplets. As the solvent evaporates, the analyte molecules are forced closer together, repel each other and break up the droplets. This process is called Coulombic fission because it is driven by repulsive [[Coulombic force]]s between charged molecules. The process repeats until the analyte is free of solvent and is a bare ion. The ions observed are created by the addition of a [[proton]] (a hydrogen ion) and denoted {{chem2|[M + H]+}}, or of another [[cation]] such as sodium ion, {{chem2|[M + Na]+}}, or the removal of a proton, {{chem2|[M \s H]-}}. Multiply charged ions such as {{chem2|[M + 2H]^{2+} }} are often observed. For [[macromolecules]], there can be many charge states, occurring with different frequencies; the charge can be as great as {{chem2|[M + 25H]^{25+} }}, for example.{{Citation needed|date=October 2024}}

====Probe electrospray ionization====
{{Main|Probe electrospray ionization}}
Probe electrospray ionization (PESI) is a modified version of electrospray, where the capillary for sample solution transferring is replaced by a sharp-tipped solid needle with periodic motion.<ref>{{cite journal |author1=Hiraoka K. |author2=Nishidate K. |author3=Mori K. |author4=Asakawa D. |author5=Suzuki S. | title = Development of probe electrospray using a solid needle | journal = [[Rapid Communications in Mass Spectrometry]] | date = 2007| volume = 21 | pages = 3139–3144 | doi = 10.1002/rcm.3201 | pmid = 17708527 | issue = 18| bibcode = 2007RCMS...21.3139H }}</ref>