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| [[File:Mass spectrometer ei ci ion source.jpg|thumb|290px|Mass spectrometer EI/CI ion source]]
| | Apart from the Clash of Clans hack tool; there might be also hack tools for the other games. Americans can check out those hacks and obtain the people which they need. It is sure that will have lost among fun once they take the hack tool available.<br><br> |
| An '''ion source''' is an electro-magnetic device that is used to create [[Ion|charged particles]] such as atomic and molecular ions.
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| Ion sources are used primarily to form ions for [[Mass spectrometry|mass spectrometers]], [[optical emission spectrometer]]s, [[particle accelerators]], [[Ion implantation|ion implanters]] and [[Ion thruster|ion engines]].
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| This article summarizes the many different types of ion sources used in different analytical instruments and applications. | |
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| ==Electron and chemical ionization==
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| === Electron ionization ===
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| {{main|Electron ionization}}
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| Electron ionization is widely used in mass spectrometry, particularly for [[organic chemistry|organic]] molecules. The [[Phase (matter)|gas phase]] reaction producing electron ionization is
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| :<math>M + e^- \to M^{+\bullet} + 2e^- </math>
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| where M is the atom of molecule being ionized, <math>e^-</math> is the electron, and <math>M^{+\bullet}</math> is the resulting ion.
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| The electrons may be created by an [[arc discharge]] between a [[cathode]] and an [[anode]].
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| === Chemical ionization ===
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| {{main|Chemical ionization}}
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| Chemical ionization is a lower energy process than [[electron ionization]].<ref>Munson, M.S.B.; Field, F.H. ''J. Am. Chem. Soc.'' '''1966''', ''88'', 2621-2630. [http://dx.doi.org/10.1021/ja00964a001 Chemical Ionization Mass Spectrometry. I. General Introduction].</ref> The lower energy yields less [[fragmentation (chemistry)|fragmentation]], and usually a simpler [[spectrum]]. A typical CI spectrum has an easily identifiable molecular ion.<ref name="MSPA">{{cite book|last=de Hoffmann|first=Edmond|coauthors=Vincent Stroobant|title=Mass Spectrometry: Principles and Applications|publisher=John Wiley & Sons, Ltd.|location=Toronto|year=2003|edition=Second|pages=14| isbn = 0-471-48566-7 }}</ref>
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| In a CI experiment, ions are produced through the collision of the analyte with ions of a reagent gas in the ion source. Some common reagent gases include: [[methane]], [[ammonia]], and [[isobutane]]. Inside the ion source, the reagent gas is present in large excess compared to the analyte. Electrons entering the source will preferentially ionize the reagent gas. The resultant collisions with other reagent gas molecules will create an ionization [[Plasma (physics)|plasma]]. Positive and negative ions of the analyte are formed by reactions with this plasma. For example, protonation occurs by
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| :<math>CH_4 + e^- \to CH_4^+ + 2e^-</math> (primary ion formation),
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| :<math>CH_4 + CH_4^+ \to CH_5^+ + CH_3</math> (reagent ion formation),
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| :<math>M + CH_5^+ \to CH_4 + [M + H]^+</math> (product ion formation, e.g. protonation).
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| ===Radioactive ion sources===
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| A small piece of radioactive material, for instance <sup>63</sup>[[Nickel|Ni]] or <sup>241</sup>[[Americium|Am]], can be used to ionize a gas. This is used in ionization [[smoke detector]]s and [[ion mobility spectrometer]]s.
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| === Ion-attachment ionization ===
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| {{main|Ion attachment mass spectrometry}}
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| Ion-attachment ionization is similar to [[chemical ionization]] in which a cation is attached to the analyte molecule in a reactive collision:
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| :<math>M + X^+ + A \to MX^+ + A</math>
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| 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|date=|first=|last=|coauthors=|volume=|issue=|pages=|id= |url=|format= }}</ref>
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| ==Gas discharge ion sources==
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| These ion sources use a [[plasma source]] or [[electric discharge]] to create ions.
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| === Inductively coupled plasma ===
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| {{main|Inductively coupled plasma}}
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| Ions can be created in an inductively coupled plasma, which is a [[plasma (physics)|plasma]] source in which the [[energy]] is supplied by [[electrical current]]s which are produced by [[electromagnetic induction]], that is, by time-varying [[magnetic field]]s.<ref>A. Montaser and D. W. Golightly, eds. Inductively Coupled Plasmas in Analytical Atomic Spectrometry, VCH Publishers, Inc., New York, 1992.</ref>
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| === Microwave induced plasma ===
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| {{main|Microwave induced plasma}}
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| [[Microwave]]s are capable of exciting electrodeless gas discharges to create ions.
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| === Glow discharge ===
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| {{main|Glow discharge}}
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| Ions can be created in an electric glow discharge.
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| ===Spark ionization===
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| {{main|Spark ionization}}
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| [[Electric spark]] ionization is used to produce gas phase [[ion]]s from a solid sample. When incorporated with a mass spectrometer the complete instrument is referred to as a spark ionization mass spectrometer or as a spark source mass spectrometer (SSMS).<ref>{{cite journal | author = H. E. Beske, A. Hurrle and K. P. Jochum | title = Part I. Principles of spark source mass spectrometry (SSMS) | year = 1981 | journal = [[Fresenius' Journal of Analytical Chemistry]] | volume = 309 | issue = 4 | pages = 258–261 | doi = 10.1007/BF00488596}}</ref>
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| ===Closed drift ion sources===
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| These ion sources use a radial magnetic field in an annular cavity in order to confine electrons for ionizing a gas. They are used for [[ion implantation]] and for space propulsion ([[Hall effect thruster]]s).
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| ==Desorption ionization==
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| === Aerosol laser desorption and ionization ===
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| In aerosol time-of-flight mass spectrometry, 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 | year = 1995 | author = Carson, P | journal = Journal of Aerosol Science | volume = 26 | pages = 535 | last2 = Neubauer | first2 = K | last3 = Johnston | first3 = M | last4 = Wexler | first4 = A | issue = 4 }}</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 | year = 2000 | author = Guazzotti, S | journal = Journal of Aerosol Science | volume = 31 | pages = 182 | last2 = Coffee | first2 = K | last3 = Prather | first3 = K }}</ref>
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| === Desorption ionization on silicon ===
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| {{main|Soft laser desorption}}
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| Desorption ionization on silicon (DIOS) refers to laser desorption/ionization of a sample deposited on a porous silicon surface.
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| === Fast atom bombardment ===
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| {{main|Fast atom bombardment}}
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| In fast atom bombardment (FAB) the analytes is mixed with a non-volatile chemical protection environment called a [[Matrix Isolation|matrix]] and is bombarded under vacuum with a high energy (4000 to 10,000 [[electron volts]]) beam of atoms.<ref name="pmid7306100">{{cite journal | author = Morris HR, Panico M, Barber M, Bordoli RS, Sedgwick RD, Tyler A | title = Fast atom bombardment: a new mass spectrometric method for peptide sequence analysis | journal = Biochem. Biophys. Res. Commun. | volume = 101 | issue = 2 | pages = 623–31 | year = 1981 | pmid = 7306100 | doi =10.1016/0006-291X(81)91304-8 }}</ref> The atoms are typically from an inert gas such as [[argon]] or [[xenon]]. Common matrices include [[glycerol]], [[thioglycerol]], [[3-nitrobenzyl alcohol]] (3-NBA), [[18-Crown-6]] ether, [[2-nitrophenyloctyl ether]], [[sulfolane]], [[diethanolamine]], and [[triethanolamine]]. This technique is similar to [[secondary ion mass spectrometry]] and [[plasma desorption mass spectrometry]].
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| === Field desorption ===
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| {{main|Field desorption}}
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| 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. | year =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 M<sup>+.</sup> and less often, protonated molecules <math>[M+H]^+</math>.
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| === Liquid metal ion sources ===
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| {{main|Liquid metal ion source}}
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| In a [[Liquid metal ion source]] (LMIS), a metal (typically [[gallium]]) is heated to the liquid state and provided at the end of a capillary or a needle. Then a [[Taylor cone]] is formed under the application of a strong electric field. As the cone's tip get sharper, the electric field becomes stronger, until ions are produced by field evaporation. These ion sources are particularly used in [[ion implantation]] or in [[focused ion beam]] instruments.
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| === Matrix-assisted laser desorption/ionization ===
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| {{main|Matrix-assisted laser desorption/ionization}}
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| 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.
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| === Surface-enhanced laser desorption/ionization ===
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| {{main|Surface-enhanced laser desorption/ionization}}
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| 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 [[Dissociation constant#Protein-ligand binding|affinity]] with the analyte compound.<ref>{{cite journal |author=Tang N, Tornatore P, Weinberger SR |title=Current developments in SELDI affinity technology |journal=Mass spectrometry reviews |volume=23 |issue=1 |pages=34–44 |year=2004 |pmid=14625891 |doi=10.1002/mas.10066}}</ref>
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| ==Spray ionization==
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| === Atmospheric pressure chemical ionization ===
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| {{main|Atmospheric pressure chemical ionization}}
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| Atmospheric pressure chemical ionization is a form of [[chemical ionization]] which takes place at atmospheric pressure.<ref name="pmid17405144">{{cite journal |author=Prakash C, Shaffer CL, Nedderman A |title=Analytical strategies for identifying drug metabolites |journal=Mass spectrometry reviews |volume=26 |issue=3 |pages=340–69 |year=2007 |pmid=17405144 |doi=10.1002/mas.20128}}</ref> A spray of solvent is heated to relatively high temperatures (above 400 degrees Celsius), sprayed with high flow rates of nitrogen and the entire aerosol cloud is subjected to a [[corona discharge]] that creates ions. APCI is not as "soft" an ionization technique as ESI.<ref name="pmid16723751">{{cite journal |author=Zaikin VG, Halket JM |title=Derivatization in mass spectrometry--8. Soft ionization mass spectrometry of small molecules |journal=European Journal of Mass Spectrometry |volume=12 |issue=2 |pages=79–115 |year=2006 |pmid=16723751 |doi=10.1255/ejms.798}}</ref>
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| === Atmospheric pressure photoionization ===
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| {{main|Atmospheric pressure photoionization}}
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| Atmospheric pressure photoionization uses a source of photons, usually a vacuum UV (VUV) lamp, to ionize the analyte with single photon ionization process. Analogous to other AP ion sources a spray of solvent is heated to relatively high temperatures (above 400 degrees Celsius) and sprayed with high flow rates of nitrogen for desolvation. The resulting aerosol cloud is subjected to UV radiation to create ions.
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| === Atmospheric pressure laser ionization ===
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| {{main|Atmospheric-pressure laser ionization}}
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| Atmospheric pressure laser ionization uses UV laser light sources to ionize the analyte via a multi photon ionization process (1+1 REMPI). The method is selective towards particular molecules like PAHs.
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| === Electrospray ionization ===
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| {{main|Electrospray ionization}}
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| In electrospray ionization, a [[liquid]] is pushed through a very small, charged and usually [[metal]], [[capillary]].<ref>{{cite journal | doi = 10.1002/mas.1280090103 | author = Fenn, J. B.; Mann, M.; Meng, C. K.; Wong, S. F.; Whitehouse, C. M. | title = Electrospray Ionization-Principles and Practice | journal = [[Mass Spectrometry Reviews]] | year = 1990 | volume = 9 | issue = 1 | pages = 37–70}}</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 [[acid]]s, [[base (chemistry)|bases]] or [[buffer (chemistry)|buffers]] are often added to this solution too. The analyte exists as an [[ion]] in solution either in its anion or cation form. Because like [[electric charge|charges]] repel, the liquid pushes itself out of the capillary and forms an [[Particulate|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 <math>[M+H]^+</math>, or of another [[cation]] such as [[sodium]] ion, <math>[M+Na]^+</math>, or the removal of a proton, <math>[M-H]^-</math>. Multiply charged ions such as <math>[M+2H]^{2+}</math> are often observed. For large [[macromolecules]], there can be many charge states, occurring with different frequencies; the charge can be as great as <math>[M+25H]^{25+}</math>, for example.
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| === Probe electrospray ionization ===
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| {{main|Probe electrospray ionization}}
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| 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 periodical motion.<ref>{{cite journal | author = Hiraoka K.; Nishidate K.; Mori K.; Asakawa D.; Suzuki S. | title = Development of probe electrospray using a solid needle | journal = [[Rapid Communications in Mass Spectrometry]] | year = 2007| volume = 21 | pages = 3139–3144 | doi = 10.1002/rcm.3201 | pmid = 17708527 | issue = 18}}</ref>
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| ===Sonic spray ionization===
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| {{main|sonic spray ionization}}
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| Sonic spray ionization is method for creating [[ion]]s from a liquid [[solution]], for example, a mixture of [[methanol]] and [[water]].<ref name="pmid8779414">{{cite journal |author=Hirabayashi A, Sakairi M, Koizumi H |title=Sonic spray mass spectrometry |journal=Anal. Chem. |volume=67 |issue=17 |pages=2878–82 |year=1995 |pmid=8779414|doi=10.1021/ac00113a023}}</ref> A [[pneumatic]] [[nebulizer]] is used to turn the solution into a [[supersonic]] spray of small droplets. Ions are formed when the solvent [[evaporate]]s and the statistically unbalanced charge distribution on the droplets leads to a net charge and complete desolvation results in the formation of ions.
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| === Thermospray ionization ===
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| {{main|Thermospray ionization}}
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| Thermospray is a form of atmospheric pressure ionization in [[mass spectrometry]]. It transfers ions from the liquid phase to the gas phase for analysis. It is particularly useful in [[liquid chromatography-mass spectrometry]].<ref>{{cite journal | last1 = Blakley | first1 = C. R. | last2 = Carmody | first2 = J. J. | last3 = Vestal | first3 = M. L. | year = 1980| title = Liquid Chromatograph-Mass Spectrometer for Analysis of Nonvolatile Samples | url = | journal = Analytical Chemistry | volume = 1980 | issue = 52| pages = 1636–1641|doi=10.1021/ac50061a025 }}</ref>
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| === Surface ionization ===
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| {{main|Thermal ionization}}
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| Surface ionization (also known as thermal ionization, or contact ionization) involves spraying vaporized, neutral atoms onto a hot surface, from which the atoms re-evaporate in ionic form. To generate positive ions, the atomic species should have a low [[ionization energy]], and the surface should have a high [[work function]]. This technique is most suitable for [[alkali metal|alkali]] atoms (Li, Na, K, Rb, Cs) which have low ionization energies and are easily evaporated.<ref>{{cite doi|10.1063/1.1139776}}</ref>
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| To generate negative ions, the atomic species should have a high [[electron affinity]], and the surface should have a low work function. This second approach is most suited for [[halogen]] atoms Cl, Br, I, At.<ref>[http://www.ornl.gov/~webworks/cpr/v823/pres/110496.pdf "A Negative-Surface Ionization for Generation of Halogen Radioactive Ion Beams"]</ref>
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| ==Ambient ionization== | |
| {{main|Ambient ionization}}
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| In ambient ionization, ions are formed outside the mass spectrometer without sample preparation or separation.<ref name=Cooks2006>{{Cite journal | last1 = Cooks | first1 = R. Graham | last2 = Ouyang | first2 = Zheng | last3 = Takats | first3 = Zoltan | last4 = Wiseman | first4 = Justin M. | year = 2006 | title = Ambient Mass Spectrometry | journal = Science | volume = 311 | issue = 5767 | pages = 1566–70 | doi = 10.1126/science.1119426 | pmid = 16543450 | postscript = <!--None-->|bibcode = 2006Sci...311.1566C }}</ref>
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| === Desorption electrospray ionization ===
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| {{main|Desorption electrospray ionization}}
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| Desorption electrospray ionization uses an [[electrospray]] source to create charged droplets that are directed at a solid sample a few millimeters to a few centimeters away. The charged droplets pick up the sample through interaction with the surface and then form highly charged ions that can be sampled into a mass spectrometer.<ref name="pmid16237663">{{cite journal |author=Takáts Z, Wiseman JM, Cooks RG |title=Ambient mass spectrometry using desorption electrospray ionization (DESI): instrumentation, mechanisms and applications in forensics, chemistry, and biology |journal=Journal of mass spectrometry : JMS |volume=40 |issue=10 |pages=1261–75 |year=2005 |pmid=16237663 |doi=10.1002/jms.922}}</ref>
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| === Direct analysis in real time ===
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| {{main|DART ion source}}
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| A Direct analysis in real time source operates by exposing the sample to a dry gas stream (typically helium or nitrogen) that contains long-lived electronically or vibronically excited neutral [[atoms]] or [[molecules]] (or [[Metastability in molecules|"metastables"]]). [[Excited state]]s are typically formed in the DART source by creating a [[glow discharge]] in a chamber through which the gas flows.
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| ===Matrix-assisted laser desorption electrospray ionization===
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| {{main|Matrix-assisted laser desorption electrospray ionization}}
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| Matrix-assisted laser desorption electrospray ionization (MALDESI)<ref>Sampson JS, Hawkridge AM, Muddiman DC (2006). "Generation and detection of multiply charged peptides and proteins by matrix-assisted laser desorption electrospray ionization (MALDESI) Fourier transform ion cyclotron resonance mass spectrometry". J. Am. Soc. Mass Spectrom. 17 (12): 1712–6. {{doi|10.1016/j.jasms.2006.08.003}}. PMID 16952462.</ref> is an atmospheric pressure ionization source for generation of multiply charged ions. An ultraviolet or infrared laser is directed onto a solid or liquid sample containing the analyte of interest and matrix (UV = organic acid, IR = sacrificial analyte or water of hydration) desorbing neutral analyte molecules which are postionized by interaction with electrosprayed solvent droplets generating multiply charged ions.
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| === Laser Ablation Electrospray Ionization ===
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| {{main|Laser Ablation Electrospray Ionization}}
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| Laser Ablation Electrospray Ionization (LAESI) is an [[ambient ionization]] method for mass spectrometry that combines laser ablation from a mid-infrared (mid-IR) laser with a secondary [[electrospray ionization]] (ESI) process.
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| ==Particle accelerators==
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| In [[particle accelerator]]s an ion source creates a [[particle beam]] at the beginning of the machine, the ''source''. The technology to create ion sources for particle accelerators depends strongly on the type of particle that needs to be generated: [[electron]]s, [[proton]]s, [[Hydride|H<sup>-</sup> ion]] or a [[Heavy ions]].
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| Electrons are generated with an [[electron gun]], and there are many varieties of these.
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| Protons are generated with a [[plasma (physics)|plasma]]-based device, like a [[duoplasmatron]] or a [[magnetron]].
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| [[hydride|H<sup>-</sup>]] ions are generated with a [[magnetron]] or a [[Penning ionization|Penning]] source. A magnetron consists of a central cylindrical cathode surrounded by an anode. The discharge voltage is typically greater than 150 V and the current drain is around 40 A. A [[magnetic field]] of about 0.2 [[tesla (unit)|tesla]] is parallel to the [[cathode]] axis. Hydrogen gas is introduced by a pulsed gas valve. [[Caesium]] is often used to lower the [[work function]] of the cathode, enhancing the amount of ions that are produced.
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| For a [[Penning ionization|Penning source]], a strong magnetic field parallel to the electric field of the sheath guides electrons and ions on cyclotron spirals from cathode to cathode. Fast H-minus ions are generated at the cathodes as in the magnetron. They are slowed down due to the charge exchange reaction as they migrate to the plasma aperture. This makes for a beam of ions that is colder than the ions obtained from a magnetron.
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| [[Heavy ions]] can be generated with an [[electron cyclotron resonance]] ion source. The use of electron cyclotron resonance (ECR) ion sources for the production of intense beams of highly charged ions has immensely grown over the last decade. ECR ion sources are used as injectors into linear accelerators, Van-de-Graaff generators or cyclotrons in nuclear and elementary particle physics. In atomic and surface physics ECR ion sources deliver intense beams of highly charged ions for collision experiments or for the investigation of surfaces. For the highest charge states, however, [[Electron beam ion source]]s (EBIS) are needed. They can generate even bare ions of mid-heavy elements. The [[Electron beam ion trap]] (EBIT), based on the same principle, can produce up to bare uranium ions and can be used as an ion source as well.
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| [[Heavy ions]] can also be generated with an [[Ion Gun]] which typically uses the thermionic emission of electrons to ionize a substance in its gaseous state. Such instruments are typically used for surface analysis.
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| ===Theory of Operation===
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| Gas flows through the ion source between the [[anode]] and the [[cathode]]. A positive [[voltage]] is applied to the anode. This voltage, combined with the high [[magnetic field]] between the tips of the internal and external cathodes allow a [[plasma (physics)|plasma]] to start. [[Ions]] from the plasma are repelled by the anode [[electric field]]. This creates an ion beam.<ref>{{cite web | url = http://www.advanced-energy.com/en/upload/File/Sources/SL-ION-230-02.pdf | title = Ion Beam Sources | publisher = [[Advanced Energy]] | accessdate = 2006-12-14 |archiveurl = http://web.archive.org/web/20061018152802/http://www.advanced-energy.com/en/upload/File/Sources/SL-ION-230-02.pdf <!-- Bot retrieved archive --> |archivedate = 2006-10-18}}</ref>
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| ==Ion source applications==
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| *Surface cleaning and pretreatment for large area deposition
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| *[[Thin-film deposition]]
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| *Deposition of Thick [[Diamond-like carbon]] (DLC) Films
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| *Surface roughening of [[polymers]] for improved [[adhesion]] and/or [[biocompatibility]]<ref>{{cite web | url = http://www.advanced-energy.com/en/Ion.html | title = Ion Beam Source Technology | publisher = Advanced Energy | accessdate = 2006-12-14}}</ref>
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| ==References==
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| {{reflist}}
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| ==See also==
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| * [[Cold cathode]]
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| * [[Hot filament]]
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| * [[Ion beam]]
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| * [[Ionization]]
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| * [[Harold R. Kaufman]]
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| * [[Plasma source]]
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| * [[RF antenna ion source]]
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| * [[On-Line Isotope Mass Separator]]
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| {{Mass spectrometry}}
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| [[Category:Ion source]]
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| [[Category:Ions]]
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| [[Category:Accelerator physics]]
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