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| '''Gas phase ion chemistry''' is a field of science encompassed within both [[chemistry]] and [[physics]]. It is the science that studies [[ion]]s and [[molecule]]s in the gas phase, most often enabled by some form of [[mass spectrometry]]. By far the most important applications for this science is in studying the [[thermodynamic]]s and [[chemical kinetics|kinetics]] of reactions.<ref name=Aubry2000>{{Cite journal | last = Aubry | first = C. | year = 2000 | title = Correlating thermochemical data for gas-phase ion chemistry | journal = International Journal of Mass Spectrometry | volume = 200 | issue = 1-3 | pages = 277 | doi = 10.1016/S1387-3806(00)00323-7 | postscript = <!--None-->}}</ref><ref>[http://www.iupac.org/publications/pac/1998/pdf/7010x1969.pdf Pure & Appl. Chem., Vol. 70, No. 10, pp. 1969-1976, 1998.]</ref> For example one application is in studying the [[thermodynamics]] of the [[solvation]] of ions. Ions with small [[solvation]] spheres of 1, 2, 3... solvent molecules can be studied in the gas phase and then extrapolated to bulk solution.
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| ==Theory==
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| ===Transition state theory===
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| {{Main|Transition state theory}}
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| Transition state theory is the theory of the rates of elementary reactions which assumes a special type of [[chemical equilibrium]] (quasi-equilibrium) between reactants and activated complexes.<ref>{{GoldBookRef|title=Transition State Theory|file= T06470}}</ref>
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| ===RRKM theory===
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| {{main|RRKM theory}}
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| RRKM theory is used to compute simple estimates of the [[unimolecular ion decomposition]] [[reaction rates]] from a few characteristics of the [[potential energy surface]].
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| ==Gas phase ion formation==
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| The process of converting an [[atom]] or [[molecule]] into an [[ion]] by adding or removing charged particles such as [[electron]]s or other ions can occur in the gas phase. These processes are an important component of gas phase ion chemistry.
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| ===Associative ionization===
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| {{main|Associative ionization}}
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| Associative ionization is a gas phase reaction in which two [[atom]]s or [[molecule]]s interact to form a single product [[ion]].<ref>{{GoldBookRef|title=associative ionization|file= A00475}}</ref>
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| :<math>A^* + B \to AB^{+\bullet} + e^-</math>
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| where species A with excess internal energy (indicated by the asterisk) interacts with B to form the ion AB<sup>+</sup>.
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| One or both of the interacting species may have excess [[internal energy]].
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| ===Charge-exchange ionization===
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| {{main|Charge-exchange ionization}}
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| Charge-exchange ionization (also called '''charge-transfer ionization''') is a gas phase reaction between an [[ion]] and a neutral species
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| :<math>A^+ + B \to A + B^+</math>
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| in which the charge of the ion is transferred to the neutral.<ref>{{GoldBookRef|title=charge-exchange ionization|file= C00989}}</ref>
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| ===Chemical ionization===
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| {{main|chemical ionization}}
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| In chemical ionization, ions are produced through the reaction of ions of a reagent gas with other species.<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> Some common reagent gases include: [[methane]], [[ammonia]], and [[isobutane]].
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| ===Chemi-ionization===
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| {{main|Chemi-ionization}}
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| Chemi-ionization can be represented by
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| :<math>G^* + M \to M^{+\bullet} + e^- + G</math>
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| where G is the excited state species (indicated by the superscripted asterisk), and M is the species that is ionized by the loss of an [[electron]] to form the [[Radical (chemistry)|radical]] [[cation]] (indicated by the superscripted "plus-dot").
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| ===Penning ionization===
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| {{main|Penning ionization}}
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| Penning ionization refers to the interaction between a gas-phase excited-state atom or molecule G<sup>*</sup> and a target molecule M resulting in the formation of a radical molecular cation M<sup>+.</sup>, an electron e<sup>−</sup>, and a neutral gas molecule G:<ref>{{GoldBookRef|title=Penning gas mixture|file= P04476}}</ref>
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| :<math>G^* + M \to M^{+\bullet} + e^- + G</math>
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| Penning ionization occurs when the target molecule has an [[ionization potential]] lower than the internal energy of the excited-state atom or molecule. [[associative ionization|Associative]] Penning ionization can also occur:
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| :<math>G^* + M \to MG^{+\bullet} + e^-</math>
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| ==Fragmentation==
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| There are many important [[Dissociation (chemistry)|dissociation]] reactions that take place in the gas phase.
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| ===Collision-induced dissociation===
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| {{main|Collision-induced dissociation}}
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| CID (also called collisionally activated dissociation - CAD) is a method used to fragment molecular [[ion]]s in the gas phase.<ref name="pmid16401509">{{cite journal |author=Wells JM, [[Scott A. McLuckey|McLuckey SA]] |title=Collision-induced dissociation (CID) of peptides and proteins |journal=Meth. Enzymol. |volume=402 |issue= |pages=148–85 |year=2005 |pmid=16401509 |doi=10.1016/S0076-6879(05)02005-7}}</ref><ref name="pmid15481084">{{cite journal |author=Sleno L, Volmer DA |title=Ion activation methods for tandem mass spectrometry |journal=Journal of mass spectrometry : JMS |volume=39 |issue=10 |pages=1091–112 |year=2004 |pmid=15481084 |doi=10.1002/jms.703}}</ref> The molecular ions collide with neutral gas molecules such as [[helium]], [[nitrogen]] or [[argon]]. In the collision some of the kinetic energy is converted into [[internal energy]] which results in fragmentation.
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| ===Charge remote fragmentation===
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| {{main|Charge remote fragmentation}}
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| Charge remote fragmentation is a type of [[covalent bond]] breaking that occurs in a gas phase [[ion]] in which the cleaved bond is not adjacent to the location of the charge.<ref name="pmid11199379">{{cite journal |author=Cheng C, Gross ML |title=Applications and mechanisms of charge-remote fragmentation |journal=Mass Spectrom Rev |volume=19 |issue=6 |pages=398–420 |year=2000 |pmid=11199379 |doi=10.1002/1098-2787(2000)19:6<398::AID-MAS3>3.0.CO;2-B}}</ref><ref name=Gross2000>{{Cite journal | last = Gross | first = M. | year = 2000 | title = Charge-remote fragmentation: an account of research on mechanisms and applications | journal = International Journal of Mass Spectrometry | volume = 200 | issue = 1-3 | pages = 611 | doi = 10.1016/S1387-3806(00)00372-9 | postscript = <!--None--> }}</ref>
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| ==Charge transfer reactions==
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| There are several types of charge-transfer reactions<ref>{{GoldBookRef|title=charge-transfer reaction (in mass spectrometry)|file=C01005}}</ref> (also known as charge-permutation reactions<ref>{{GoldBookRef|title=charge-permutation reaction|file=M04002}}</ref>): partial-charge transfer
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| :<math>A^{2+} + B \to A^+ + B^+</math>,
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| charge-stripping reaction<ref>{{GoldBookRef|title=charge-stripping reaction|file=C01001}}</ref>
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| :<math>A^+ + B \to A^{2+} + B + e^-</math>,
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| and charge-inversion reaction<ref>{{GoldBookRef|title=charge-inversion mass spectrum|file=C00992}}</ref> positive to negative
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| :<math>A^+ + B \to A^- + B^{2+} </math>
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| and negative to positive
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| :<math>A^- + B \to A^+ + B + 2e^-</math>.
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| ==See also==
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| *[[Adiabatic ionization]]
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| *[[Mass-analyzed ion kinetic energy spectrometry]]
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| *[[Plasma (physics)]]
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| *[[Michael T. Bowers]]
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| *[[R. Graham Cooks]]
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| *[[Helmut Schwarz]]
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| == References ==
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| {{Reflist}}
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| ==Bibliography==
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| {{refbegin}}
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| *Fundamentals of gas phase ion chemistry, Keith R. Jennings (ed.), Dordrecht, Boston, Kluwer Academic, 1991, pp. 226-8
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| *Gas Phase Ion Chemistry, Michael T. Bowers, ed., Academic Press, New York, 1979
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| *Gas Phase Ion Chemistry Vol 2.; Bowers, M.T., Ed.; Academic Press: New York, 1979
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| *Gas Phase Ion Chemistry Vol 3., Michael T. Bowers, ed., Academic Press, New York, 1983
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| {{refend}}
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| ==External links==
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| * http://webbook.nist.gov/chemistry/ion/
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| [[Category:Mass spectrometry]]
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Hi there, I am Sophia. To perform lacross is the thing I love most of all. Some time in the past she chose to live in Alaska and her mothers and fathers reside nearby. Credit authorising is how she tends to make a residing.
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