Editing Ion source (section)

===Laser desorption ionization===
{{Unreferenced section|date=October 2024}}
[[File:Maldi.PNG|thumb|300px|Diagram of a MALDI ion source]]
Matrix-assisted laser desorption/ionization (MALDI) is a soft ionization technique. The sample is mixed with a matrix material. Upon receiving a laser pulse, the matrix absorbs the laser energy and it is thought that primarily the matrix is desorbed and ionized (by addition of a proton) by this event. The analyte molecules are also desorbed. The matrix is then thought to transfer proton to the analyte molecules (e.g., protein molecules), thus charging the analyte.

====Surface-assisted laser desorption/ionization====
Surface-assisted laser desorption/ionization (SALDI) is a [[soft laser desorption]] technique used for analyzing [[biomolecule]]s by [[mass spectrometry]].<ref name="SunnerDratz1995">{{cite journal|last1=Sunner|first1=Jan.|last2=Dratz|first2=Edward.|last3=Chen|first3=Yu-Chie.|title=Graphite surface-assisted laser desorption/ionization time-of-flight mass spectrometry of peptides and proteins from liquid solutions|journal=Analytical Chemistry|volume=67|issue=23|date=1995|pages=4335–4342|issn=0003-2700|doi=10.1021/ac00119a021|pmid=8633776}}</ref><ref name="DattelbaumIyer2006">{{cite journal|last1=Dattelbaum|first1=Andrew M|last2=Iyer|first2=Srinivas|title=Surface-assisted laser desorption/ionization mass spectrometry|journal=Expert Review of Proteomics|volume=3|issue=1|date=2006|pages=153–161|issn=1478-9450|doi=10.1586/14789450.3.1.153|pmid=16445359|s2cid=39538990|url=https://zenodo.org/record/1235756|type=Submitted manuscript}}</ref> In its first embodiment, it used [[graphite]] matrix.<ref name="SunnerDratz1995" /> At present, laser desorption/ionization methods using other [[inorganic]] matrices, such as [[nanomaterials]], are often regarded as SALDI variants. A related method named "ambient SALDI" - which is a combination of conventional SALDI with ambient mass spectrometry incorporating the [[DART ion source]] - has also been demonstrated.<ref name="ZhangLi2012">{{cite journal|last1=Zhang|first1=Jialing|last2=Li|first2=Ze|last3=Zhang|first3=Chengsen|last4=Feng|first4=Baosheng|last5=Zhou|first5=Zhigui|last6=Bai|first6=Yu|last7=Liu|first7=Huwei|title=Graphite-Coated Paper as Substrate for High Sensitivity Analysis in Ambient Surface-Assisted Laser Desorption/Ionization Mass Spectrometry|journal=Analytical Chemistry|volume=84|issue=7|date=2012|pages=3296–3301|issn=0003-2700|doi=10.1021/ac300002g|pmid=22380704}}</ref>

====Surface-enhanced laser desorption/ionization====
{{Main|Surface-enhanced laser desorption/ionization}}
Surface-enhanced laser desorption/ionization (SELDI) is a variant of MALDI that is used for the analysis of [[protein]] [[mixture]]s  that uses a target modified to achieve biochemical [[Receptor affinity|affinity]] with the analyte compound.<ref>{{cite journal |vauthors=Tang N, Tornatore P, Weinberger SR |title=Current developments in SELDI affinity technology |journal=Mass Spectrometry Reviews |volume=23 |issue=1 |pages=34–44 |date=2004 |pmid=14625891 |doi=10.1002/mas.10066|bibcode = 2004MSRv...23...34T }}</ref>

====Desorption ionization on silicon====
{{Main|Desorption ionization on silicon}}
Desorption ionization on silicon (DIOS) refers to laser desorption/ionization of a sample deposited on a porous silicon surface.<ref name="BuriakWei1999">{{cite journal|last1=Buriak|first1=Jillian M.|title=Desorption-ionization mass spectrometry on porous silicon|last2=Wei|first2=Jing|author-link3=Gary Siuzdak|last3=Siuzdak|first3=Gary|journal=Nature|volume=399|issue=6733|date=1999|pages=243–246|issn=0028-0836|doi=10.1038/20400|pmid=10353246|bibcode=1999Natur.399..243W|s2cid=4314372}}</ref>

====Smalley source====
A laser vaporization cluster source produces ions using a combination of laser desorption ionization and supersonic expansion.<ref name="Duncan2012">{{cite journal|last1=Duncan|first1=Michael A.|title=Invited Review Article: Laser vaporization cluster sources|journal=Review of Scientific Instruments|volume=83|issue=4|pages=041101–041101–19|date=2012|issn=0034-6748|doi=10.1063/1.3697599|pmid=22559508|bibcode=2012RScI...83d1101D}}</ref> The '''Smalley source''' (or '''Smalley cluster source''')<ref>{{cite book|title=Laser Ablation and Desorption|url=https://books.google.com/books?id=iWfddcv0quwC&pg=PA628|date=10 December 1997|publisher=Academic Press|isbn=978-0-08-086020-6|pages=628–}}</ref> was developed by [[Richard Smalley]] at [[Rice University]] in the 1980s and was central to the discovery of [[fullerene]]s in 1985.<ref name="Smalley1997">{{cite journal|last1=Smalley|first1=Richard|title=Discovering the fullerenes|journal=Reviews of Modern Physics|volume=69|issue=3|date=1997|pages=723–730|issn=0034-6861|doi=10.1103/RevModPhys.69.723|bibcode=1997RvMP...69..723S}}</ref><ref name="Johnston2002">{{cite book|author=Roy L. Johnston|title=Atomic and Molecular Clusters|url=https://books.google.com/books?id=pxztbPhmBeIC&pg=PA150|date=25 April 2002|publisher=CRC Press|isbn=978-1-4200-5577-1|pages=150–}}</ref>

====Aerosol ionization====
In [[aerosol mass spectrometry]] with time-of-flight analysis, micrometer sized solid aerosol particles extracted from the atmosphere are simultaneously desorbed and ionized by a precisely timed laser pulse as they pass through the center of a time-of-flight ion extractor.<ref>{{Cite journal | doi = 10.1016/0021-8502(94)00133-J | title = On-line chemical analysis of aerosols by rapid single-particle mass spectrometry | date = 1995 | author = Carson, P | journal = Journal of Aerosol Science | volume = 26 | pages = 535–545 | last2 = Neubauer | first2 = K | last3 = Johnston | first3 = M | last4 = Wexler | first4 = A | issue = 4 | bibcode = 1995JAerS..26..535C }}</ref><ref>{{Cite journal | doi = 10.1016/S0021-8502(00)90189-7 | title = Real time monitoring of size-resolved single particle chemistry during INDOEX-IFP 99 | date = 2000 | author = Guazzotti, S | journal = Journal of Aerosol Science | volume = 31 | pages = 182–183 | last2 = Coffee | first2 = K | last3 = Prather | first3 = K | bibcode = 2000JAerS..31..182G }}</ref>