View source for Xenon

{{about|the chemical element}}
{{pp-move-indef}}
{{Infobox xenon}}
'''Xenon''' is a [[chemical element]] represented by the [[chemical symbol|symbol]] '''Xe'''. The element name is pronounced {{IPA-en|ˈzɛnɒn|}}, {{respell|ZEN|on}} or {{IPA-en|ˈziːnɒn|}}, {{respell|ZEE|non}}.<!-- ({{pron-en|ˈzɛnɒn}}<ref>Xenon, entry in the [[Oxford English Dictionary]], prepared by J. A. Simpson and E. S. C. Weiner, vol. 20, second edition, Oxford: Clarendon Press, 1989. ISBN 0-19-861232-X (vol. 20), ISBN 0-19-861186-2 (set.)</ref> {{respell|ZEN|on}} or {{IPA-en|ˈziːnɒn|}}<ref>[http://dictionary.reference.com/browse/xenon Xenon], entry in Dictionary.com Unabridged (v 1.1), accessed on line February 19, 2007. Transcribed into IPA.</ref> {{respell|ZEE|non}}) --> Its [[atomic number]] is 54. A colorless, heavy, odorless [[noble gas]], xenon occurs in the [[Earth's atmosphere]] in trace amounts.<ref>{{cite web
 |author=Staff|year=2007
 |url=http://www.infoplease.com/ce6/sci/A0852881.html
 |title=Xenon|work=Columbia Electronic Encyclopedia
 |edition=6th edition|publisher=Columbia University Press
 |accessdate=2007-10-23}}</ref> Although generally unreactive, xenon can undergo a few [[chemical reaction]]s such as the formation of [[xenon hexafluoroplatinate]], the first [[noble gas compound]] to be synthesized.<ref name="lanl">{{cite web
 |author=Husted, Robert; Boorman, Mollie
 |date=December 15, 2003
 |url=http://periodic.lanl.gov/elements/54.html|title=Xenon
 |publisher=Los Alamos National Laboratory, Chemical Division
 |accessdate=2007-09-26
}}</ref><ref>{{cite book 
 |last=Rabinovich|first=Viktor Abramovich
 |coauthors=Vasserman, A. A.; Nedostup, V. I.; Veksler, L. S.|title=Thermophysical properties of neon, argon, krypton, and xenon|year=1988|edition=English-language
 |publisher=Hemisphere Publishing Corp.
 |location=Washington, DC|isbn=0891166750
 |url=http://adsabs.harvard.edu/abs/1988wdch...10.....R 
 |accessdate=2009-04-02}}—National Standard Reference Data Service of the USSR. Volume 10.</ref><ref name="beautiful" />

Naturally occurring xenon consists of [[Isotopes of xenon|nine stable isotopes]]. There are also over 40 unstable isotopes that undergo [[radioactive decay]]. The isotope ratios of xenon are an important tool for studying the early history of the [[Solar System]].<ref name="kaneoka" /> Xenon-135 is produced as a result of [[nuclear fission]] and acts as a [[neutron absorber]] in [[nuclear reactor]]s.<ref name="stacey" />

Xenon is used in [[xenon flash lamp|flash lamps]]<ref name="burke" /> and [[xenon arc lamp|arc lamps]],<ref name="mellor" /> and as a [[general anaesthesia|general anesthetic]].<ref name="Sanders">{{cite journal
 |author=Sanders, Robert D.; Ma, Daqing; Maze, Mervyn
 |title=Xenon: elemental anaesthesia in clinical practice
 |journal=British Medical Bulletin
 |year=2005|volume=71|issue=1|pages=115–135
 |doi=10.1093/bmb/ldh034
 |pmid=15728132}}</ref> The first [[excimer laser]] design used a xenon [[Dimer (chemistry)|dimer]] molecule (Xe<sub>2</sub>) as its [[Active laser medium|lasing medium]],<ref name="basov" /> and the earliest [[laser]] designs used xenon flash lamps as [[Laser pumping|pumps]].<ref name="toyserkani" /> Xenon is also being used to search for hypothetical [[weakly interacting massive particles]]<ref name="ball" /> and as the [[propellant]] for [[ion thruster]]s in [[spacecraft]].<ref name="saccoccia" />

==History==
Xenon was discovered in England by [[William Ramsay]] and [[Morris Travers]] on July 12, 1898, shortly after their discovery of the elements [[krypton]] and [[neon]]. They found it in the residue left over from evaporating components of [[liquid air]].<ref>{{cite journal
 |author=Ramsay, W.; Travers, M. W. 
 |title=On the extraction from air of the companions of argon, and neon|journal=Report of the Meeting of the British Association for the Advancement of Science
 |year=1898|page=828}}</ref><ref>{{cite web
 |url=http://education.jlab.org/itselemental/ele054.html
 |title=It's Elemental - Xenon|accessdate=2007-06-16
 |last=Gagnon|first=Steve|publisher=Thomas Jefferson National Accelerator Facility}}</ref> Ramsay suggested the name ''xenon'' for this gas from the [[Greek language|Greek]] word ''ξένον'' [xenon], neuter singular form of ''ξένος'' [xenos], meaning 'foreign(er)', 'strange(r)', or 'guest'.<ref>{{cite book 
 |author=Anonymous|editor=Daniel Coit Gilman, Harry Thurston Peck, Frank Moore Colby
 |year=1904|title=The New International Encyclopædia
 |publisher=Dodd, Mead and Company|page=906
}}</ref><ref>{{cite book
 |author=Staff|year=1991|url=http://books.google.com/?id=IrcZEZ1bOJsC&pg=PA513
 |title=The Merriam-Webster New Book of Word Histories
 |page=513|publisher=Merriam-Webster, Inc.
 |isbn=0877796033}}</ref> In 1902, Ramsay estimated the proportion of xenon in the Earth's atmosphere as one part in 20 million.<ref>{{cite journal
 |last=Ramsay|first=William
 |title=An Attempt to Estimate the Relative Amounts of Krypton and of Xenon in Atmospheric Air
 |journal=Proceedings of the Royal Society of London
 |year=1902|volume=71|pages=421–426
 |doi=10.1098/rspl.1902.0121}}</ref>

During the 1930s, engineer [[Harold Eugene Edgerton|Harold Edgerton]] began exploring [[strobe light]] technology for [[high speed photography]]. This led him to the invention of the xenon flash lamp, in which light is generated by sending a brief electrical current through a tube filled with xenon gas. In 1934, Edgerton was able to generate flashes as brief as one [[microsecond]] with this method.<ref name="burke" /><ref>{{cite web
 |author=Anonymous|title=History
 |url=http://www.millisecond-cine.com/history.html
 |publisher=Millisecond Cinematography
 |accessdate=2007-11-07
}}</ref><ref>{{cite web
 |last=Paschotta|first=Rüdiger
 |date=November 1, 2007
 |url=http://www.rp-photonics.com/lamp_pumped_lasers.html
 |title=Lamp-pumped lasers
 |work=Encyclopedia of Laser Physics and Technology
 |publisher=RP Photonics|accessdate=2007-11-07}}</ref>

In 1939, Albert R. Behnke Jr. began exploring the causes of "drunkenness" in deep-sea divers. He tested the effects of varying the breathing mixtures on his subjects, and discovered that this caused the divers to perceive a change in depth. From his results, he deduced that xenon gas could serve as an [[Anesthesia|anesthetic]]. Although Lazharev, in Russia, apparently studied xenon anesthesia in 1941, the first published report confirming xenon anesthesia was in 1946 by J. H. Lawrence, who experimented on mice. Xenon was first used as a surgical anesthetic in 1951 by Stuart C. Cullen, who successfully operated on two patients.<ref>{{cite journal
 |author=Marx, Thomas; Schmidt, Michael; Schirmer, Uwe; Reinelt, Helmut|title=Xenon anesthesia
 |journal=Journal of the Royal Society of Medicine
 |year=2000|volume=93|pages=513–517
 |url=http://www.jrsm.org/cgi/reprint/93/10/513.pdf
 |accessdate=2007-10-02 |format=PDF
 |pmid=11064688|issue=10|pmc=1298124}}</ref>

Xenon and the other noble gases were for a long time considered to be completely chemically inert and not able to form [[chemical compound|compound]]s. However, while teaching at the [[University of British Columbia]], [[Neil Bartlett (chemist)|Neil Bartlett]] discovered that the gas [[platinum hexafluoride]] (PtF<sub>6</sub>) was a powerful [[Redox|oxidizing]] agent that could oxidize oxygen gas (O<sub>2</sub>) to form [[dioxygenyl hexafluoroplatinate]] (O<sub>2</sub><sup>+</sup>[PtF<sub>6</sub>]<sup>–</sup>).<ref>{{cite journal|title=Dioxygenyl hexafluoroplatinate (V), O<sub>2</sub><sup>+</sup>[PtF<sub>6</sub>]<sup>–</sup>
 |author=Bartlett, Neil; Lohmann, D. H.
 |journal=Proceedings of the Chemical Society
 |publisher=Chemical Society|location=London
 |issue=3|page=115|year=1962
 |doi = 10.1039/PS9620000097}}</ref> Since O<sub>2</sub> and xenon have almost the same first [[ionization potential]], Bartlett realized that platinum hexafluoride might also be able to oxidize xenon. On March 23, 1962, he mixed the two gases and produced the first known compound of a noble gas, [[xenon hexafluoroplatinate]].<ref name="bartlettxe">{{cite journal
 |title=Xenon hexafluoroplatinate (V) Xe<sup>+</sup>[PtF<sub>6</sub>]<sup>–</sup>|author=Bartlett, N.
 |journal=Proceedings of the Chemical Society 
 |publisher=Chemical Society|location=London
 |issue=6|page=218|year=1962
 |doi=10.1039/PS9620000197}}</ref><ref name="beautiful">{{cite web|url=http://www.chem.umn.edu/class/2301/barany03f/fun/beautiful1.pdf
 |title=Chemistry at its Most Beautiful
 |accessdate=2007-09-13|last=Freemantel|first=Michael
 |date=August 25, 2003|format=PDF
 |publisher=Chemical & Engineering News}}</ref> Bartlett thought its composition to be Xe<sup>+</sup>[PtF<sub>6</sub>]<sup>–</sup>, although later work has revealed that it was probably a mixture of various xenon-containing salts.<ref name="grahm">{{cite journal
 |last=Graham|first=L.|year=2000
 |coauthors=Graudejus, O.; Jha N.K.; Bartlett, N.
 |title=Concerning the nature of XePtF<sub>6</sub>
 |journal=Coordination Chemistry Reviews|volume = 197
 |pages=321–334|doi=10.1016/S0010-8545(99)00190-3}}</ref><ref>{{cite book
 |first=A. F.|last=Holleman|coauthors=Wiberg, Egon
 |editors=Bernhard J. Aylett|year=2001
 |others=translated by Mary Eagleson and William Brewer
 |title=Inorganic Chemistry|location=San Diego
 |publisher=Academic Press|isbn=0-12-352651-5}}; translation of ''Lehrbuch der Anorganischen Chemie'', originally founded by A. F. Holleman, [http://books.google.com/books?id=vEwj1WZKThEC&pg=PA395 continued by Egon Wiberg], edited by Nils Wiberg, Berlin: de Gruyter, 1995, 34th edition, ISBN 3-11-012641-9.</ref><ref>{{cite web
 |last=Steel|first=Joanna|year=2007
 |url=http://chemistry.berkeley.edu/publications/news/2006/bio_bartlett.php
 |title=Biography of Neil Bartlett
 |publisher=College of Chemistry, University of California, Berkeley|accessdate=2007-10-25}}</ref> Since then, many other xenon compounds have been discovered,<ref>{{cite journal
 |last=Bartlett|first=Neil|date=2003-09-09
 |url=http://pubs.acs.org/cen/80th/noblegases.html
 |title=The Noble Gases|journal=Chemical & Engineering News
 |volume=81|issue=36|publisher=American Chemical Society
 |accessdate=2007-10-01}}</ref> along with some compounds of the noble gases [[argon]], [[krypton]], and [[radon]], including [[argon fluorohydride]] (HArF),<ref>{{cite journal
 |first=Leonid|last=Khriachtchev|coauthors=Pettersson, Mika; Runeberg, Nino; Lundell, Jan; Räsänen, Markku
 |date =2000-08-24|title = A stable argon compound
 |journal = Nature|volume = 406|pages = 874–876
 |doi = 10.1038/35022551|url = http://www.nature.com/nature/journal/v406/n6798/abs/406874a0.html|accessdate=2008-06-04
 |pmid=10972285|issue=6798}}</ref> [[krypton difluoride]] (KrF<sub>2</sub>),<ref>{{cite book
 |author=Lynch, C. T.; Summitt, R.; Sliker, A.
 |year=1980|title=CRC Handbook of Materials Science
 |publisher=CRC Press|isbn=087819231X}}</ref><ref>{{cite journal
 |title=Krypton Difluoride: Preparation and Handling
 |author=MacKenzie, D. R.|year=1963|journal=Science
 |volume=141|issue=3586|page=1171
 |doi=10.1126/science.141.3586.1171|pmid=17751791}}</ref> and [[radon fluoride]].<ref>{{cite journal
 |author=Paul R. Fields, Lawrence Stein, and Moshe H. Zirin
 |title=Radon Fluoride
 |journal=Journal of the American Chemical Society
 |year=1962|volume=84|issue=21|pages=4164–4165
 |doi=10.1021/ja00880a048}}</ref> By 1971, more than 80 xenon compounds were known.<ref name="CRC">{{cite web
 |url=http://www.chemnetbase.com/periodic_table/elements/xenon.htm|title=Xenon|work=Periodic Table Online
 |publisher=CRC Press|accessdate=2007-10-08| archiveurl = http://web.archive.org/web/20070410040717/http://chemnetbase.com/periodic_table/elements/xenon.htm| archivedate = April 10, 2007}}</ref><ref>{{cite journal|last=Moody|first=G. J.
 |title=A Decade of Xenon Chemistry
 |journal=Journal of Chemical Education|year=1974|volume=51
 |pages=628–630|url=http://www.eric.ed.gov/ERICWebPortal/recordDetail?accno=EJ111480|accessdate=2007-10-16
 |doi=10.1021/ed051p628}}</ref>

==Characteristics==
[[Image:Xenon-flash.gif|thumb|left|upright|[[Xenon flash]]|alt=An animated image of a flash discharge in a coil-shaped lamp. The discharge color is first blue and then white.]]
An atom of xenon is defined as having a nucleus with 54 [[proton]]s. At [[standard temperature and pressure]], pure xenon gas has a density of 5.761&nbsp;kg/m<sup>3</sup>, about 4.5 times the surface density of the Earth's atmosphere, 1.217&nbsp;kg/m<sup>3</sup>.<ref>{{cite web
 |last=Williams|first=David R.|date=April 19, 2007
 |url=http://nssdc.gsfc.nasa.gov/planetary/factsheet/earthfact.html|title=Earth Fact Sheet|publisher=NASA
 |accessdate=2007-10-04}}</ref> As a liquid, xenon has a density of up to 3.100&nbsp;g/mL, with the density maximum occurring at the triple point.<ref name="detectors">{{cite book|first=Elena|last=Aprile|coauthors=Bolotnikov, Aleksey E.; Doke, Tadayoshi
 |title=Noble Gas Detectors|publisher=Wiley-VCH|year=2006
 |isbn=3527609636|url=http://books.google.com/?id=tsnHM8x6cHAC&pg=PT1|pages=8–9}}</ref> Under the same conditions, the density of solid xenon, 3.640&nbsp;g/cm<sup>3</sup>, is larger than the average density of [[granite]], 2.75&nbsp;g/cm<sup>3</sup>.<ref name="detectors" /> Using [[pascal (unit)|gigapascal]]s of [[pressure]], xenon has been forced into a metallic phase.<ref>{{cite journal
 |last=Caldwell|first=W. A.|year=1997|coauthors=Nguyen, J.; Pfrommer, B.; Louie, S.; Jeanloz, R.
 |title = Structure, bonding and geochemistry of xenon at high pressures
 |journal=Science|volume=277|pages=930–933
 |doi=10.1126/science.277.5328.930}}</ref>

Solid xenon changes from [[face-centered cubic]] (fcc) to [[Close-packing of spheres|hexagonal close packed]] (hcp) crystal phase under pressure and begins to turn metallic at about 140&nbsp;GPa, with no noticeable volume change in the hcp phase. It is completely metallic at 155&nbsp;GPa. When metalized, xenon looks sky blue because it absorbs red light and transmits other visible frequencies. Such behavior is unusual for a metal and is explained by the relatively small widths of the electron bands in metallic xenon.<ref>{{cite web|first=E.|last=Fontes
 |title=Golden Anniversary for Founder of High-pressure Program at CHESS|publisher=Cornell University
 |url=http://news.chess.cornell.edu/articles/2006/RuoffAnnv.html|accessdate=2009-05-30}}</ref><ref>{{cite journal
 |author=Eremets, Mikhail I.; Gregoryanz, Eugene A.; Struzhkin, Victor V.; Mao, Ho-Kwang; Hemley, Russell J.; Mulders, Norbert; Zimmerman, Neil M.|title=Electrical Conductivity of Xenon at Megabar Pressures
 |journal=Physical Review Letters|volume=85
 |issue=13|pages=2797–2800|year=2000
 |doi=10.1103/PhysRevLett.85.2797|pmid=10991236}}</ref>

Xenon is a member of the zero-[[Valence (chemistry)|valence]] elements that are called [[noble gas|noble]] or [[inert]] [[gas]]es. It is inert to most common chemical reactions (such as combustion, for example) because the outer [[valence shell]] contains eight electrons. This produces a stable, minimum energy configuration in which the outer electrons are tightly bound.<ref>{{cite web
 |last=Bader|first=Richard F. W.
 |url=http://miranda.chemistry.mcmaster.ca/esam/
 |title=An Introduction to the Electronic Structure of Atoms and Molecules
 |publisher=McMaster University|accessdate=2007-09-27}}</ref> However, xenon can be [[Oxidation|oxidized]] by powerful oxidizing agents, and many xenon compounds have been synthesized.

In a [[gas-filled tube]], xenon emits a [[blue]] or [[lavender (color)|lavender]]ish glow when the gas is excited by [[Electric arc|electrical discharge]]. Xenon emits a band of [[Spectral line|emission lines]] that span the visual spectrum,<ref>{{cite web
 |last=Talbot|first=John|url=http://web.physik.rwth-aachen.de/~harm/aixphysik/atom/discharge/index1.html
 |title=Spectra of Gas Discharges
 |publisher=Rheinisch-Westfälische Technische Hochschule Aachen|accessdate=2006-08-10}}</ref>
but the most intense lines occur in the region of blue light, which produces the coloration.<ref>{{cite book
 |first=William Marshall|last=Watts|year=1904
 |title=An Introduction to the Study of Spectrum Analysis
 |publisher=Longmans, Green, and co.
 |location=London}}</ref>

==Occurrence and production==
Xenon is a [[trace gas]] in [[Earth's atmosphere]], occurring at 0.087±0.001&nbsp;[[Parts-per notation|parts per million]] (μL/L), or approximately 1 part per 11.5 million,<ref name="kirk">{{cite book
 |last=Hwang|first=Shuen-Cheng
 |coauthors=Robert D. Lein, Daniel A. Morgan
 |chapter=Noble Gases
 |title=Kirk-Othmer Encyclopedia of Chemical Technology
 |publisher=Wiley|year=2005|edition=5th
 |doi=10.1002/0471238961.0701190508230114.a01
 |isbn=047148511X}}</ref> and is also found in gases emitted from some [[mineral spring]]s.

Xenon is obtained commercially as a byproduct of the separation of air into [[oxygen]] and [[nitrogen]]. After this separation, generally performed by [[fractional distillation]] in a double-column plant, the [[liquid oxygen]] produced will contain small quantities of krypton and xenon. By additional fractional distillation steps, the liquid oxygen may be enriched to contain 0.1–0.2% of a krypton/xenon mixture, which is extracted either via adsorption onto [[silica gel]] or by distillation. Finally, the krypton/xenon mixture may be separated into [[krypton]] and xenon via distillation.<ref>{{cite book
 |first=Frank G.|last=Kerry|year=2007
 |title=Industrial Gas Handbook: Gas Separation and Purification|pages=101–103|publisher=CRC Press
 |isbn=0849390052|url=http://books.google.com/?id=cXNmyTTGbRIC&pg=PA101
}}</ref><ref>{{cite web
 |url=http://www.c-f-c.com/specgas_products/xenon.htm
 |title=Xenon - Xe|accessdate=2007-09-07
 |date=August 10, 1998|publisher=CFC StarTec LLC
}}</ref> Extraction of a liter of xenon from the atmosphere requires 220 [[watt-hour]]s
of energy.<ref name="singh">{{cite web
 |last=Singh|first=Sanjay|date=May 15, 2005
 |url=http://www.expresshealthcaremgmt.com/20050515/criticare10.shtml
 |title=Xenon: A modern anaesthetic
 |publisher=Indian Express Newspapers Limited
 |accessdate=2007-10-10}}</ref> Worldwide production of xenon in 1998 was estimated at 5,000–7,000&nbsp;m<sup>3</sup>.<ref name="ullmann">{{cite book
 |last=Häussinger|first=Peter
 |coauthors=Glatthaar, Reinhard; Rhode, Wilhelm;
Kick, Helmut; Benkmann, Christian; Weber, Josef; Wunschel, Hans-Jörg; Stenke, Viktor; Leicht, Edith; Stenger, Hermann
 |chapter=Noble Gases
 |title=Ullmann's Encyclopedia of Industrial Chemistry
 |publisher=Wiley|year=2001|edition=6th
 |doi=10.1002/14356007.a17_485|isbn=3527201653}}</ref> Because of its low abundance, xenon is much more expensive than the lighter noble gases—approximate prices for the purchase of small quantities in Europe in 1999 were 10&nbsp;[[Euro|€]]/L for xenon, 1&nbsp;€/L for krypton, and 0.20&nbsp;€/L for neon.<ref name="ullmann" />

Within the Solar System, the [[nucleon]] fraction of xenon is {{Nowrap|1.56 × 10<sup>−8</sup>}}, for an [[Abundance of the chemical elements|abundance]] of one part in 64&nbsp;million of the total mass.<ref>{{cite book
 |first=David|last=Arnett|year=1996
 |title=Supernovae and Nucleosynthesis
 |publisher=Princeton University Press
 |location=Princeton, New Jersey
 |isbn=0-691-01147-8|url=http://books.google.com/?id=PXGWGnPPo0gC&pg=PA30}}</ref> Xenon is relatively rare in the [[Sun]]'s atmosphere, on [[Earth]], and in [[asteroid]]s and [[comet]]s. The planet [[Jupiter]] has an unusually high abundance of xenon in its atmosphere; about 2.6 times as much as the Sun.<ref name="mahaffy">{{cite journal
|last=Mahaffy|first=P. R.
|coauthors=Niemann, H. B.; Alpert, A.; Atreya, S. K.; Demick, J.; Donahue, T. M.; Harpold, D. N.; Owen, T. C.
|title=Noble gas abundance and isotope ratios in the atmosphere of Jupiter from the Galileo Probe Mass Spectrometer
 |journal=Journal of Geophysical Research
 |year=2000|volume=105|issue=E6|pages=15061–15072
 |url=http://adsabs.harvard.edu/abs/2000JGR...10515061M
 |accessdate=2007-10-01
 |doi = 10.1029/1999JE001224}}</ref> This high abundance remains unexplained and may have been caused by an early and rapid buildup of [[planetesimal]]s—small, subplanetary bodies—before the [[solar nebula|presolar disk]] began to heat up.<ref>{{cite journal
 |last=Owen|first=Tobias|coauthors=Mahaffy, Paul; Niemann, H. B.; Atreya, Sushil; Donahue, Thomas; Bar-Nun, Akiva; de Pater, Imke|title=A low-temperature origin for the planetesimals that formed Jupiter
 |journal=Nature|year=1999|volume=402
 |issue=6759|pages=269–270
 |url=http://adsabs.harvard.edu/abs/1999Natur.402..269O
 |accessdate=2007-02-04|doi = 10.1038/46232
 |pmid=10580497}}</ref> (Otherwise, xenon would not have been trapped in the planetesimal ices.) The problem of the low terrestrial xenon may potentially be explained by [[covalent bond]]ing of xenon to oxygen within [[quartz]], hence reducing the outgassing of xenon into the atmosphere.<ref>{{cite journal
 |first=Chrystèle|last=Sanloup|coauthors=''et al.''
 |title=Retention of Xenon in Quartz and Earth's Missing Xenon|journal=Science|year=2005|volume=310
 |issue=5751|pages=1174–1177|doi=10.1126/science.1119070
 |pmid=16293758}}</ref>

Unlike the lower mass noble gases, the normal [[stellar nucleosynthesis]] process inside a star does not form xenon. Elements more massive than [[iron-56]] have a net energy cost to produce through fusion, so there is no energy gain for a star when creating xenon.<ref>{{cite book
 |first=Donald D.|last=Clayton|year=1983
 |title=Principles of Stellar Evolution and Nucleosynthesis
 |publisher=University of Chicago Press
 |isbn=0226109534|url=http://books.google.com/?id=imjwZdXExQIC&pg=PA604}}</ref> Instead, xenon is formed during [[supernova]] explosions,<ref name="heymann">{{cite conference
 |last=Heymann|first=D.|coauthors=Dziczkaniec, M.
 |title=Xenon from intermediate zones of supernovae
 |booktitle=Proceedings 10th Lunar and Planetary Science Conference
 |pages=1943–1959|publisher=Pergamon Press, Inc.
 |date=March 19–23, 1979|location=Houston, Texas
 |url=http://adsabs.harvard.edu/abs/1979LPSC...10.1943H
 |accessdate=2007-10-02}}</ref> by the slow neutron capture process ([[s-process]]) of [[red giant]] stars that have exhausted the hydrogen at their cores and entered the [[asymptotic giant branch]],<ref>{{cite journal
 |author=Beer, H.; Kaeppeler, F.; Reffo, G.; Venturini, G.
 |title=Neutron capture cross-sections of stable xenon isotopes and their application in stellar nucleosynthesis
 |journal=Astrophysics and Space Science |volume=97
 |issue=1 |month=November |year=1983 |pages=95–119
 |doi=10.1007/BF00684613 |bibcode=1983Ap&SS..97...95B}}</ref> in classical [[nova]]e explosions<ref>{{cite journal
 |last=Pignatari|first=M.
 |coauthors=Gallino, R.; Straniero, O.; Davis, A.
 |title=The origin of xenon trapped in presolar mainstream SiC grains
 |journal=Memorie della Societa Astronomica Italiana
 |year=2004|volume=75|pages=729–734
 |url=http://adsabs.harvard.edu/abs/2004MmSAI..75..729P
 |accessdate=2007-10-26}}</ref> and from the radioactive decay of elements such as [[iodine]], [[uranium]] and [[plutonium]].<ref name="caldwell" />

==Isotopes and isotopic studies==
{{main|Isotopes of xenon}}

Naturally occurring xenon is made of nine [[stable isotope|stable]] [[isotope]]s, the most of any element with the exception of tin, which has ten. Xenon and tin are the only elements to have more than seven stable isotopes.<ref>{{cite book
 |first=J. B.|last=Rajam|year=1960
 |title=Atomic Physics|edition=7th
 |publisher=S. Chand and Co.|location=Delhi
 |isbn=812191809X}}</ref> The isotopes <sup>124</sup>Xe, <sup>134</sup>Xe and <sup>136</sup>Xe are predicted to undergo [[double beta decay]], but this has never been observed so they are considered to be stable.<ref>{{cite journal
 |last=Barabash|first=A. S.
 |title=Average (Recommended) Half-Life Values for Two-Neutrino Double-Beta Decay
 |journal=Czechoslovak Journal of Physics
 |year=2002|volume=52|issue=4|pages=567–573
 |doi=10.1023/A:1015369612904}}</ref>
Besides these stable forms, there are over 40 unstable isotopes that have been studied. <sup>129</sup>Xe is produced by [[beta decay]] of <sup>129</sup>[[iodine|I]], which has a [[half-life]] of 16&nbsp;million years, while <sup>131m</sup>Xe, <sup>133</sup>Xe, <sup>133m</sup>Xe, and <sup>135</sup>Xe are some of the [[nuclear fission|fission]] products of both <sup>235</sup>[[uranium|U]] and <sup>239</sup>[[plutonium|Pu]],<ref name="caldwell">{{cite web
 |last=Caldwell|first=Eric|month=January|year=2004
 |url=http://wwwrcamnl.wr.usgs.gov/isoig/period/xe_iig.html
 |title=Periodic Table - Xenon|work=Resources on Isotopes
 |publisher=USGS|accessdate=2007-10-08}}</ref> and therefore used as indicators of nuclear explosions.

Nuclei of two of the stable [[isotopes of xenon]], <sup>129</sup>Xe and <sup>131</sup>Xe, have non-zero intrinsic [[angular momentum|angular momenta]] ([[Spin (physics)|nuclear spins]], suitable for [[nuclear magnetic resonance]]). The nuclear spins can be aligned beyond ordinary polarization levels by means of circularly polarized light and [[rubidium]] vapor.<ref>{{cite journal
 |last=Otten|first=Ernst W.|year=2004
 |title=Take a breath of polarized noble gas
 |journal=Europhysics News|volume=35|issue=1
 |accessdate=2008-06-04|doi=10.1051/epn:2004109
 |page=16}}</ref> The resulting [[spin polarization]] of xenon [[atomic nucleus|nuclei]] can surpass 50% of its maximum possible value, greatly exceeding the equilibrium value dictated by the [[Boltzmann distribution]] (typically 0.001% of the maximum value at [[room temperature]], even in the strongest [[magnet]]s). Such non-equilibrium alignment of spins is a temporary condition, and is called ''[[hyperpolarization (physics)|hyperpolarization]]''. The process of hyperpolarizing the xenon is called ''optical pumping'' (although the process is different from [[optical pumping|pumping a laser]]).<ref>{{cite journal
 |journal=Physical Review Letters|volume=96|page=053002
 |year=2006|title = Optical Pumping System Design for Large Production of Hyperpolarized <sup>129</sup>Xe
 |first=I. C.|last=Ruset|coauthors=Ketel, S.; Hersman, F. W.|doi=10.1103/PhysRevLett.96.053002}}</ref>

Because a <sup>129</sup>Xe nucleus has a [[spin (physics)|spin]] of 1/2, and therefore a zero [[electric field|electric]] [[quadrupole moment]], the <sup>129</sup>Xe nucleus does not experience any quadrupolar interactions during collisions with other atoms, and thus its hyperpolarization can be maintained for long periods of time even after the laser beam has been turned off and the alkali vapor removed by condensation on a room-temperature surface. Spin polarization of <sup>129</sup>Xe it can persist from several [[second]]s for xenon atoms dissolved in [[blood]]<ref>{{
cite journal
 |first=J.|last=Wolber
 |coauthors=Cherubini, A.; Leach, M. O.; Bifone, A.
 |title = On the oxygenation-dependent <sup>129</sup>Xe ''T''<sub>1</sub> in blood
 |year = 2000|journal = NMR in Biomedicine
 |volume = 13|issue = 4|pages = 234–237
 |doi = 10.1002/1099-1492(200006)13:4<234::AID-NBM632>3.0.CO;2-K
 |pmid=10867702}}</ref> to several hours in the [[gas phase]]<ref>{{ cite journal 
 |first=B.|last=Chann|coauthors=Nelson, I. A.; Anderson, L. W.; Driehuys, B.; Walker, T. G.
 |title=<sup>129</sup>Xe-Xe molecular spin relaxation
 |year=2002|journal=Physical Review Letters
 |volume=88|issue=11|pages=113–201
 |doi=10.1103/PhysRevLett.88.113201}}</ref> and several days in deeply frozen solid xenon.<ref>{{cite encyclopedia
 |first=Gustav Konrad|last=von Schulthess
 |coauthors=Smith, Hans-Jørgen; Pettersson, Holger; Allison, David John
 |year=1998|title=The Encyclopaedia of Medical Imaging
 |page=194|publisher=Taylor & Francis
 |isbn=1901865134|url=http://books.google.com/books?id=zvDY5unRC4oC&pg=PA194}}</ref> In contrast, [[isotopes of xenon|<sup>131</sup>Xe]] has a nuclear spin value of 3/2 and a nonzero [[quadrupole moment]], and has ''T''<sub>1</sub> relaxation times in the [[millisecond]] and [[second]] ranges.<ref>{{cite journal
 |first=W. W.|last=Warren|coauthors=Norberg, R. E.
 |title=Nuclear Quadrupole Relaxation and Chemical Shift of Xe<sup>131</sup> in Liquid and Solid Xenon
 |year=1966|journal=Physical Review
 |volume=148|issue=1|pages=402–412
 |doi=10.1103/PhysRev.148.402}}</ref>

Some radioactive isotopes of xenon, for example, <sup>133</sup>Xe and <sup>135</sup>Xe, are produced by [[neutron]] irradiation of fissionable material within [[nuclear reactor]]s.<ref name="lanl" /> [[Xenon-135|<sup>135</sup>Xe]] is of considerable significance in the operation of [[nuclear reactor|nuclear fission reactors]]. <sup>135</sup>Xe has a huge [[Neutron cross-section|cross section]] for [[thermal neutron]]s, 2.6×10<sup>6</sup>&nbsp;[[Barn (unit)|barns]],<ref name="stacey">{{cite book 
 |first=Weston M.|last=Stacey|year=2007
 |title=Nuclear Reactor Physics|page=213
 |url=http://books.google.com/?id=y1UgcgVSXSkC&pg=PA213|publisher=Wiley-VCH|isbn=3527406794}}</ref> so it acts as a [[neutron absorber]] or "[[nuclear poison|poison]]" that can slow or stop the chain reaction after a period of operation. This was discovered in the earliest nuclear reactors built by the American [[Manhattan Project]] for [[plutonium]] production. Fortunately the designers had made provisions in the design to increase the reactor's reactivity (the number of neutrons per fission that go on to fission other atoms of [[nuclear fuel]]).<ref>{{cite web
 |author=Staff|url=http://www.cfo.doe.gov/me70/manhattan/hanford_operational.htm
 |title=Hanford Becomes Operational
 |work=The Manhattan Project: An Interactive History
 |publisher=U.S. Department of Energy
 |accessdate=2007-10-10}}</ref>
<sup>135</sup>Xe reactor poisoning played a major role in the [[Chernobyl_disaster#Conditions_prior_to_the_accident|Chernobyl disaster]].<ref>{{cite book
 |title=Modern Physics: An Introductory Text|year=2000
 |first=Jeremy I.|last=Pfeffer|coauthors=Nir, Shlomo
 |pages=421 ff.|publisher=Imperial College Press
 |isbn=1860942504|url=http://books.google.com/?id=KmMYWP56t98C&pg=PA421}}</ref> A shutdown or decrease of power of a reactor can result in buildup of <sub>135</sub>Xe and getting the reactor into the [[iodine pit]].

Under adverse conditions, relatively high concentrations of radioactive xenon isotopes may be found emanating from nuclear reactors due to the release of fission products from cracked [[fuel rod]]s,<ref>{{cite book
 |first=Edwards A.|last=Laws|year=2000
 |title=Aquatic Pollution: An Introductory Text
 |page=505|publisher=John Wiley and Sons
 |isbn=0471348759|url=http://books.google.com/?id=11LI7XyEIsAC&pg=PA505}}</ref> or fissioning of uranium in [[Water cooling|cooling water]].<ref>{{cite news
 |author=Staff|date=April 9, 1979
 |title=A Nuclear Nightmare|publisher=Time
 |url=http://www.time.com/time/magazine/article/0,9171,920196-4,00.html
 |accessdate=2007-10-09}}</ref> 

Because xenon is a tracer for two parent isotopes, xenon isotope ratios in [[meteorite]]s are a powerful tool for studying the [[formation of the solar system]]. The [[Iodine-xenon dating|iodine-xenon method]] of [[Radiometric dating|dating]] gives the time elapsed between [[nucleosynthesis]] and the condensation of a solid object from the [[solar nebula]]. In 1960, physicist [[John Reynolds (physicist)|John H. Reynolds]] discovered that certain [[meteorite]]s contained an isotopic anomaly in the form of an overabundance of xenon-129. He inferred that this was a [[decay product]] of radioactive [[iodine-129]]. This isotope is produced slowly by [[cosmic ray spallation]] and [[nuclear fission]], but is produced in quantity only in supernova explosions. As the half-life of <sup>129</sup>I is comparatively short on a cosmological time scale, only 16 million years, this demonstrated that only a short time had passed between the supernova and the time the meteorites had solidified and trapped the <sup>129</sup>I. These two events (supernova and solidification of gas cloud) were inferred to have happened during the early history of the [[Solar System]], as the <sup>129</sup>I isotope was likely generated before the Solar System was formed, but not long before, and seeded the solar gas cloud with isotopes from a second source. This supernova source may also have caused collapse of the solar gas cloud.<ref>{{cite book 
 |first=Donald D.|last=Clayton|year=1983
 |title=Principles of Stellar Evolution and Nucleosynthesis
 |page=75|edition=2nd|url=http://books.google.com/?id=imjwZdXExQIC&pg=PA604
 |publisher=University of Chicago Press|isbn=0226109534}}</ref><ref>{{cite web
 |author=Bolt, B. A.; Packard, R. E.; Price, P. B.
 |year=2007|url=http://content.cdlib.org/xtf/view?docId=hb1r29n709&doc.view=content&chunk.id=div00061&toc.depth=1&brand=oac&anchor.id=0
 |title=John H. Reynolds, Physics: Berkeley
 |publisher=The University of California, Berkeley
 |accessdate=2007-10-01}}</ref>

In a similar way, xenon isotopic ratios such as <sup>129</sup>Xe/<sup>130</sup>Xe and <sup>136</sup>Xe/<sup>130</sup>Xe are also a powerful tool for understanding planetary differentiation and early outgassing.<ref name="kaneoka">{{cite journal
 |last=Kaneoka|first=Ichiro|title=Xenon's Inside Story
 |journal=Science|year=1998|volume=280|issue=5365
 |pages=851–852|doi=10.1126/science.280.5365.851b}}</ref> For example, The [[atmosphere of Mars]] shows a xenon abundance similar to that of Earth:
0.08&nbsp;parts per million,<ref>{{cite web
 |last=Williams|first=David R.
 |date=September 1, 2004|url=http://nssdc.gsfc.nasa.gov/planetary/factsheet/marsfact.html
 |title=Mars Fact Sheet|publisher=NASA
 |accessdate=2007-10-10}}</ref> however Mars shows a higher proportion of <sup>129</sup>Xe than the Earth or the Sun. As this isotope is generated by radioactive decay, the result may indicate that Mars lost most of its primordial atmosphere, possibly within the first 100 million years after the planet was formed.<ref>{{cite web
 |last=Schilling|first=James
 |url=http://humbabe.arc.nasa.gov/mgcm/HTML/FAQS/thin_atm.html|title=Why is the Martian atmosphere so thin and mainly carbon dioxide?
 |publisher=Mars Global Circulation Model Group
 |accessdate=2007-10-10}}
</ref><ref>{{cite journal
 |last=Zahnle|first=Kevin J.
 |title=Xenological constraints on the impact erosion of the early Martian atmosphere
 |journal=Journal of Geophysical Research
 |year=1993|volume=98|issue=E6|pages=10,899–10,913
 |accessdate=2007-10-10
 |doi=10.1029/92JE02941}}</ref> In another example, excess <sup>129</sup>Xe found in [[carbon dioxide]] well gases from [[New Mexico]] was believed to be from the decay of [[Mantle (geology)|mantle]]-derived gases soon after Earth's formation.<ref name="caldwell" /><ref>{{cite journal
 |last=Boulos|first=M. S.|coauthors=Manuel, O.K.
 |title=The xenon record of extinct radioactivities in the Earth|journal=[[Science (journal)|Science]]
 |volume=174|issue=4016|pages=1334–1336|year=1971
 |doi=10.1126/science.174.4016.1334|pmid=17801897}}</ref>

==Compounds==
:''See also: [[:Category:Xenon compounds]]''

After Neil Bartlett's discovery in 1962 that xenon can form chemical compounds, a large number of xenon compounds have been discovered and described. Almost all known xenon compounds contain the [[electronegative]] atoms fluorine or oxygen.<ref name="harding1"/>

===Halides===
[[Image:Xenon-tetrafluoride-3D-vdW.png|thumb|[[Xenon tetrafluoride]]|alt=A model of planar chemical molecule with a blue center atom (Xe) symmetrically bonded to four peripheral atoms (fluorine).]]
[[Image:Xenon tetrafluoride.JPG|thumb|XeF<sub>4</sub> crystals, 1962|alt=Many cubic transparent crystalls in a petri dish.]]

Three [[fluoride]]s are known: [[xenon difluoride|{{chem|XeF|2}}]], [[xenon tetrafluoride|{{chem|XeF|4}}]], and [[xenon hexafluoride|{{chem|XeF|6}}]]. The fluorides are the starting point for the synthesis of almost all xenon compounds.

The solid, crystalline difluoride {{chem|XeF|2}} is formed when a mixture of [[fluorine]] and xenon gases is exposed to ultraviolet light.<ref>{{cite journal
|author=Weeks, James L.; Chernick, Cedric; Matheson, Max S.
|title=Photochemical Preparation of Xenon Difluoride
|journal=Journal of the American Chemical Society
|volume=84|page=4612|doi=10.1021/ja00882a063
|year=1962}}</ref> Ordinary daylight is sufficient.<ref>{{cite journal
|author=Streng, L. V.; Streng, A. G.
|title=Formation of Xenon Difluoride from Xenon and Oxygen Difluoride or Fluorine in Pyrex Glass at Room Temperature|journal=Inorganic Chemistry
|year=1965|volume=4|issue=9|pages=1370–1371
|doi=10.1021/ic50031a035}}</ref> Long-term heating of {{chem|XeF|2}} at high temperatures under an {{chem|NiF|2}} catalyst yields {{chem|XeF|6}}.<ref name="tramsek">{{cite journal
 |author=Tramšek, Melita; Žemva, Boris
|title=Synthesis, Properties and Chemistry of Xenon(II) Fluoride|journal=Acta Chimica Slovenica
|date=December 5, 2006|volume=53|issue=2
|pages=105–116|format=PDF|doi=10.1002/chin.200721209
|url=http://acta.chem-soc.si/53/53-2-105.pdf
|accessdate=2009-07-18}}</ref> Pyrolysis of {{chem|XeF|6}} in the presence of [[sodium fluoride|NaF]] yields high-purity {{chem|XeF|4}}.<ref>{{cite journal
|author=Ogrin, Tomaz; Bohinc, Matej; Silvnik, Joze
|title=Melting-point determinations of xenon difluoride-xenon tetrafluoride mixtures
|journal=Journal of Chemical and Engineering Data
|year=1973|volume=18|issue=4|page=402
|doi=10.1021/je60059a014}}</ref>

The xenon fluorides behave as both fluoride acceptors and fluoride donors, forming salts that contain such cations as {{chem|XeF|+}} and Xe<sub>2</sub>F<sub>3</sub><sup>+</sup>,
and anions such as XeF<sub>5</sub><sup>−</sup>, XeF<sub>7</sub><sup>−</sup>, and XeF<sub>8</sub><sup>2−</sup>. The green, paramagnetic Xe<sub>2</sub><sup>+</sup> is formed by the reduction of {{chem|XeF|2}} by xenon gas.<ref name="harding1">{{cite book|author=Harding, Charlie; Johnson, David Arthur; Janes, Rob|title = Elements of the ''p'' block
|pages=93–94|publisher=Royal Society of Chemistry
|location=Great Britain|year=2002
|isbn=0854046909|url=http://books.google.com/?id=W0HW8wgmQQsC&pg=PA93}}</ref>

{{chem|XeF|2}} is also able to form [[complex (chemistry)|coordination complex]]es with transition metal ions. Over 30 such complexes have been synthesized and characterized.<ref name="tramsek" />

Whereas the xenon fluorides are well-characterized, the other halides are not known, the only exception being the dichloride, {{chem|XeCl|2}}. Xenon dichloride is reported to be an endothermic, colorless, crystalline compound that decomposes into the elements at 80°C, formed by the high-frequency irradiation of a mixture of xenon, fluorine, and [[silicon tetrachloride|silicon]] or [[carbon tetrachloride]].<ref name="scott1">{{cite encyclopedia
|author=Scott, Thomas; Eagleson, Mary
|title = Xenon Compounds|year=1994
|encyclopedia=Concise encyclopedia chemistry
|publisher=Walter de Gruyter
|isbn=3110114518|url=http://books.google.com/books?id=Owuv-c9L_IMC&pg=PA1183|page=1183}}</ref> However, doubt has been raised as to whether {{chem|XeCl|2}} is a real compound and not merely a [[van der Waals molecule]] consisting of weakly bound Xe atoms and {{chem|Cl|2}} molecules.<ref>{{cite journal
|author=Proserpio, Davide M.; Hoffmann, Roald; Janda, Kenneth C.
|title=The xenon-chlorine conundrum: van der Waals complex or linear molecule?|year=1991|volume=113
|journal=Journal of the American Chemical Society
|page=7184|doi=10.1021/ja00019a014}}</ref> Theoretical calculations indicate that the linear molecule {{chem|XeCl|2}} is less stable than the van der Waals complex.<ref>{{cite journal
|author=Richardson, Nancy A.; Hall, Michael B.|year=1993
|title=The potential energy surface of xenon dichloride
|journal=The Journal of Physical Chemistry|volume=97
|page=10952|doi=10.1021/j100144a009}}</ref>

===Oxides and oxohalides===
Only two oxides of xenon are known: [[xenon trioxide]] ({{chem|XeO|3}}) and [[xenon tetroxide]] ({{chem|XeO|4}}), both of which are dangerously explosive and powerful oxidizing agents. Xenon dioxide (XeO<sub>2</sub>) remains elusive — only the XeOO<sup>+</sup> cation has been identified by [[infrared spectroscopy]] in solid [[argon]].<ref>{{cite journal
 |author=Zhou, M.; Zhao, Y.; Gong, Y.; Li, J.
 |title=Formation and Characterization of the XeOO<sup>+</sup> Cation in Solid Argon
 |journal=[[Journal of the American Chemical Society]]
 |year=2006|volume=128
 |issue=8
 |pmid=16492012|pages=2504–2505
 |doi= 10.1021/ja055650n}}</ref>

Xenon does not react with oxygen directly; the trioxide is formed by the hydrolysis of {{chem|XeF|6}}:<ref>{{cite book
 |first=John H.|last=Holloway|coauthors=Hope, Eric G.
 |editor=A. G. Sykes|year=1998|publisher=Academic
 |title=Advances in Inorganic Chemistry Press
 |isbn=012023646X|page=65|url=http://books.google.com/?id=6iqXRtz6p3QC&pg=PA65}}</ref>

:{{chem|XeF|6}} + 3 {{chem|H|2|O}} → {{chem|XeO|3}} + 6 HF

{{chem|XeO|3}} is weakly acidic, dissolving in alkali to form unstable ''xenate'' salts containing the {{chem|HXeO|4|−}} anion. These unstable salts easily [[disproportionation|disproportionate]] into xenon gas and ''[[perxenate]]'' salts, containing the {{chem|XeO|6|4−}} anion.<ref name="henderson">{{cite book
 |first=W.|last=Henderson
 |title = Main group chemistry|year=2000
 |publisher=Royal Society of Chemistry|pages=152–153
 |location=Great Britain|isbn=0854046178
 |url=http://books.google.com/?id=twdXz1jfVOsC&pg=PA152}}</ref>

Barium perxenate, when treated with concentrated [[sulfuric acid]], yields gaseous xenon tetroxide:<ref name="scott1" />

: {{chem|Ba|2|XeO|6}} + 2 {{chem|H|2|SO|4}} → 2 {{chem|BaSO|4}} + 2 {{chem|H|2|O}} + {{chem|XeO|4}}

To prevent decomposition, the xenon tetroxide thus formed is quickly cooled to form a pale-yellow solid. It explodes above −35.9&nbsp;°C into xenon and oxygen gas.

A number of xenon oxyfluorides are known, including {{chem|XeOF|2}}, [[xenon oxytetrafluoride|{{chem|XeOF|4}}]], {{chem|XeO|2|F|2}}, and {{chem|XeO|3|F|2}}. {{chem|XeOF|2}} is formed by the reaction of [[oxygen difluoride|{{chem|OF|2}}]] with xenon gas at low temperatures. It may also be obtained by the partial hydrolysis of {{chem|XeF|4}}. It disproportionates at −20&nbsp;°C into {{chem|XeF|2}} and {{chem|XeO|2|F|2}}.<ref name="mackay1">{{cite book
 |author=Mackay, Kenneth Malcolm; Mackay, Rosemary Ann; Henderson, W.
 |title=Introduction to modern inorganic chemistry
 |year=2002|edition=6th|publisher=CRC Press
 |isbn=0748764208|url=http://books.google.com/?id=LpJPWKT3PNcC&pg=PA497|pages=497–501}}</ref> {{chem|XeOF|4}} is formed by the partial hydrolysis of {{chem|XeF|6}},<ref>{{cite journal
 |last=Smith|first=D. F.|year=1963
 |title=Xenon Oxyfluoride
 |pmid=17810680|journal=Science|volume=140
 |doi=10.1126/science.140.3569.899
 |issue=3569|page=899}}</ref> or the reaction of {{chem|XeF|6}} with sodium perxenate, {{chem|Na|4|XeO|6}}. The latter reaction also produces a small amount of {{chem|XeO|3|F|2}}. {{chem|XeOF|4}} reacts with [[caesium fluoride|CsF]] to form the {{chem|XeOF|5|−}} anion,<ref name="mackay1" /><ref>{{ cite journal | title = On the Structure of the [XeOF<sub>5</sub>]<sup>&minus;</sup> Anion and of Heptacoordinated Complex Fluorides Containing One or Two Highly Repulsive Ligands or Sterically Active Free Valence Electron Pairs | author = K. O. Christe, D. A. Dixon, J. C. P. Sanders, G. J. Schrobilgen, S. S. Tsai, W. W. Wilson | journal = [[Inorganic Chemistry (journal)|Inorg. Chem.]] | year = 1995 | volume = 34 | issue = 7 | pages = 1868&ndash;1874 | doi = 10.1021/ic00111a039 }}</ref> while XeOF<sub>3</sub> reacts with the alkali metal fluorides [[potassium fluoride|KF]], [[rubidium fluoride|RbF]] and CsF to form the {{chem|XeOF|4|−}} anion.<ref>{{ cite journal | title = Chlorine trifluoride oxide. V. Complex formation with Lewis acids and bases | author = K. O. Christe, C. J. Schack, D. Pilipovich | journal = [[Inorganic Chemistry (journal)|Inorg. Chem.]] | year = 1972 | volume = 11 | issue = 9 | pages = 2205&ndash;2208 | doi = 10.1021/ic50115a044 }}</ref>

===Other compounds===

Recently, there has been an interest in xenon compounds where xenon is directly bonded to a less electronegative element than fluorine or oxygen, particularly [[carbon]].<ref>{{cite book
 |title=Advances in Inorganic Chemistry
 |author=Holloway, John H.; Hope, Eric G.
 |others=Contributor A. G. Sykes|publisher=Academic Press
 |year=1998|isbn=012023646X|url=http://books.google.com/?id=6iqXRtz6p3QC&pg=PA61|pages=61–90}}</ref> Electron-withdrawing groups, such as groups with fluorine substitution, are necessary to stabilize these compounds.<ref name="henderson" /> Numerous such compounds have been characterized, including:<ref name="mackay1" /><ref>{{cite journal
 |title=C<sub>6</sub>F<sub>5</sub>XeF, a versatile starting material in xenon–carbon chemistry
 |year=2004|last=Frohn|first=H
 |journal=Journal of Fluorine Chemistry|volume=125|page=981
 |doi=10.1016/j.jfluchem.2004.01.019}}</ref>

*{{chem|C|6|F|5|–Xe|+|–N≡C–CH|3}}, where C<sub>6</sub>F<sub>5</sub> is the pentafluorophenyl group.
*{{chem|[C|6|F|5|]|2|Xe}}
*{{chem|C|6|F|5|–Xe–X}}, where X is [[nitrile|CN]], F, or Cl.
*{{chem|R–C≡C–Xe|+}}, where R is {{chem|C|2|F|5|-}} or [[butyl|''tert''-butyl]].
*{{chem|C|6|F|5|–XeF|2|+}}
*{{chem|(C|6|F|5|Xe)|2|Cl|+}}

Other compounds containing xenon bonded to a less electronegative element include {{chem|F–Xe–N(SO|2|F)|2}} and {{chem|F–Xe–BF|2}}. The latter is synthesized from [[dioxygenyl]] tetrafluoroborate, {{chem|O|2|BF|4}}, at −100&nbsp;°C.<ref name="mackay1" /><ref>{{cite journal
 |doi=10.1021/ja00764a022|title=Reaction of xenon with dioxygenyl tetrafluoroborate. Preparation of FXe-BF<sub>2</sub>
 |year=1972
 |last=Goetschel|first=Charles T.|coauthors=Loos, Karl R.
 |journal=Journal of the American Chemical Society
 |volume=94|pages=3018}}</ref>

An unusual ion containing xenon is the [[tetraxenonogold(II)]] cation, {{chem|AuXe|4|2+}}, which contains Xe–Au bonds.<ref name="waikeeli2">{{cite book
 |title = Advanced Structural Inorganic Chemistry
 |author=Li, Wai-Kee; Zhou, Gong-Du; Mak, Thomas C. W.
 |editors=Gong-Du Zhou; Thomas C. W. Mak
 |publisher=Oxford University Press|year=2008
 |isbn=0199216940|url=http://books.google.com/?id=2qAa5hp6KX4C&pg=PA678|page=678}}</ref> This ion occurs in the compound {{chem|AuXe|4|(Sb|2|F|11|)|2}}, and is remarkable in having direct chemical bonds between two notoriously unreactive atoms, xenon and [[gold]], with xenon acting as a transition metal ligand.

In 1995, M. Räsänen and co-workers, scientists at the [[University of Helsinki]] in [[Finland]], announced the preparation of xenon dihydride (HXeH), and later xenon hydride-hydroxide (HXeOH), hydroxenoacetylene (HXeCCH), and other Xe-containing molecules.<ref>{{cite journal
 |last=Gerber|first=R. B.|year=2004
 |doi=10.1146/annurev.physchem.55.091602.094420
 |title=Formation of novel rare-gas molecules in low-temperature matrices
 |journal=Annual Review of Physical Chemistry 
 |volume=55|pages=55–78|pmid=15117247}}</ref> In 2008, Khriachtchev ''et al.'' reported the preparation of HXeOXeH by the [[photolysis]] of water within a [[cryogenic]] xenon matrix.<ref>{{cite journal
 |last=Khriachtchev|first=Leonid
 |coauthors=Isokoski, Karoliina; Cohen, Arik; Räsänen, Markku; Gerber, R. Benny
 |title=A Small Neutral Molecule with Two Noble-Gas Atoms: HXeOXeH
 |journal=Journal of the American Chemical Society
 |year=2008|volume=130|issue=19|pages=6114–6118
 |doi=10.1021/ja077835v|pmid=18407641}}</ref> [[Deuterium|Deuterated]] molecules, HXeOD and DXeOH, have also been produced.<ref>{{cite journal
 |last=Pettersson|first=Mika|coauthors=Khriachtchev, Leonid; Lundell, Jan; Räsänen, Markku
 |title=A Chemical Compound Formed from Water and Xenon: HXeOH|year=1999
 |journal=Journal of the American Chemical Society
 |volume=121|issue=50|pages=11904–11905
 |doi=10.1021/ja9932784}}</ref>

===Clathrates and excimers===
In addition to compounds where xenon forms a [[chemical bond]], xenon can form [[clathrate]]s—substances where xenon atoms are trapped by the [[Crystal structure|crystalline lattice]] of another compound. An example is [[xenon hydrate]] (Xe·5.75 H<sub>2</sub>O), where xenon atoms occupy vacancies in a lattice of water molecules.<ref>{{cite journal
 |doi=10.1126/science.134.3471.15|title=A molecular theory of general anesthesia
 |authorlink=Linus Pauling|journal=Science|volume=134
 |year=1961|pages=15–21|pmid=13733483
 |last=Pauling|first=L.}} Reprinted as {{cite book
 |pages=1328–1334|title=Linus Pauling: Selected Scientific Papers|volume=2|editor=Pauling, Linus; Kamb, Barclay
 |place=River Edge, New Jersey|publisher=World Scientific
 |year=2001|isbn=9810229402|url=http://books.google.com/?id=2QduA19d_X8C&pg=PA1329}}</ref> This clathrate has a melting point of 24&nbsp;°C.<ref name="henderson2">{{cite book
 |title=Main group chemistry
 |last=Henderson|first=W.|year=2000
 |publisher=Royal Society of Chemistry
 |location=Great Britain|isbn=0854046178
 |url=http://books.google.com/?id=twdXz1jfVOsC&pg=PA148|page=148}}</ref> The [[deuterate]]d version of this hydrate has also been produced.<ref>{{cite journal
 |first=Tomoko|last=Ikeda|coauthors=Mae, Shinji; Yamamuro, Osamu; Matsuo, Takasuke; Ikeda, Susumu; Ibberson, Richard M.
 |title=Distortion of Host Lattice in Clathrate Hydrate as a Function of Guest Molecule and Temperature
 |journal=Journal of Physical Chemistry A
 |date=November 23, 2000|volume=104|issue=46
 |pages=10623–10630|doi=10.1021/jp001313j}}</ref> Such [[clathrate hydrate]]s can occur naturally under conditions of high pressure,
such as in [[Lake Vostok]] underneath the [[Antarctica|Antarctic]] ice sheet.<ref>{{cite journal
 |last=McKay|first=C. P.|coauthors=Hand, K. P.; Doran, P. T.; Andersen, D. T.; Priscu, J. C.
 |title=Clathrate formation and the fate of noble and biologically useful gases in Lake Vostok, Antarctica
 |journal=Geophysical Letters|year=2003
 |volume=30|issue=13|page=35|doi=10.1029/2003GL017490}}</ref> Clathrate formation can be used to fractionally distill xenon, argon and krypton.<ref>{{cite journal
 |last=Barrer|first=R. M.|coauthors=Stuart, W. I.
 |title=Non-Stoichiometric Clathrate of Water
 |journal=Proceedings of the Royal Society of London
 |year=1957|volume=243|pages=172–189
 |doi=10.1098/rspa.1957.0213}}</ref>

Xenon can also form [[endohedral fullerene]] compounds, where a xenon atom is trapped inside a [[fullerene]] molecule. The xenon atom trapped in the fullerene can be monitored via <sup>129</sup>Xe nuclear magnetic resonance (NMR) spectroscopy. Using this technique, chemical reactions on the fullerene molecule can be analyzed, due to the sensitivity of the [[chemical shift]] of the xenon atom to its environment. However, the xenon atom also has an electronic influence on the reactivity of the fullerene.<ref>{{cite journal
 |last=Frunzi|first=Michael
 |coauthors=Cross, R. James; Saunders, Martin
 |title=Effect of Xenon on Fullerene Reactions 
 |journal=Journal of the American Chemical Society
 |year=2007
 |pmid=17924634|volume=129
 |doi=10.1021/ja075568n
 |issue=43|page=13343}}</ref>

While xenon atoms are at their [[stationary state|ground energy state]], they repel each other and will not form a bond. When xenon atoms becomes energized, however, they can form an [[excimer]] (excited dimer) until the electrons return to the [[ground state]]. This entity is formed because the xenon atom tends to fill its outermost [[Electron shell|electronic shell]], and can briefly do this by adding an electron from a neighboring xenon atom. The typical lifetime of a xenon excimer is 1–5&nbsp;ns, and the decay releases [[photon]]s with [[wavelength]]s of about 150 and 173&nbsp;[[Nanometre|nm]].<ref>{{cite book
 |first=William Thomas|last=Silfvast
 |year=2004|title=Laser Fundamentals
 |publisher=Cambridge University Press
 |isbn=0521833450|url=http://books.google.com/?id=x3VB2iwSaxsC&pg=RA1-PA152
}}</ref><ref>{{cite book
 |first=John G.|last=Webster|year=1998
 |title=The Measurement, Instrumentation, and Sensors Handbook
 |publisher=Springer|isbn=3540648305
 |url=http://books.google.com/?id=b7UuZzf9ivIC&pg=PT2427}}</ref> Xenon can also form dimers with other elements, such as the [[halogen]]s [[bromine]], [[chlorine]] and [[fluorine]].<ref>{{cite book
 |first=Charles|last=McGhee|year=1997
 |coauthors=Taylor, Hugh R.; Gartry, David S.; Trokel, Stephen L.
 |title=Excimer Lasers in Ophthalmology
 |publisher=Informa Health Care
 |isbn=1853172537|url=http://books.google.com/?id=pg0bUc_GcVoC&pg=PA4}}</ref>

==Applications==
Although xenon is rare and relatively expensive to extract from the [[Earth's atmosphere]], it still has a number of applications.

===Illumination and optics===
====Gas-discharge lamps====
Xenon is used in light-emitting devices called xenon flash lamps, which are used in [[Flash (photography)|photographic flashes]] and stroboscopic lamps;<ref name="burke">{{cite book
 |first=James|last=Burke|year=2003
 |title=Twin Tracks: The Unexpected Origins of the Modern World
 |publisher=Oxford University Press
 |isbn=0743226194|page=33}}</ref> to excite the [[active laser medium|active medium]] in [[laser]]s which then generate [[coherent light]];<ref>{{cite web
 |author=Staff|year=2007
 |url=http://www.praxair.com/praxair.nsf/1928438066cae92d85256a63004b880d/32f3a328e11bb600052565660052c139?OpenDocument
 |title=Xenon Applications|publisher=Praxair Technology
 |accessdate=2007-10-04}}</ref> and, occasionally, in [[Bactericide|bactericidal]] lamps.<ref>{{cite journal
 |last=Baltás|first=E.|coauthors=Csoma, Z.; Bodai, L.; Ignácz, F.; Dobozy, A.; Kemény, L.
 |title=A xenon-iodine electric discharge bactericidal lamp 
 |journal=Technical Physics Letters
 |year=2003|volume=29|issue=10|pages=871–872
 |doi=10.1134/1.1623874}}</ref> The first solid-state [[laser]], invented in 1960, was pumped by a xenon flash lamp,<ref name="toyserkani">{{cite book
 |last=Toyserkani|first=E.|year=2004
 |coauthors=Khajepour, A.; Corbin, S.|page=48
 |title=Laser Cladding|publisher=CRC Press
 |isbn=0849321727|url=http://books.google.com/?id=zfvbyCHzVqMC&pg=PA48}}</ref> and lasers used to power [[inertial confinement fusion]] are also pumped by xenon flash lamps.<ref>{{cite journal
 |last=Skeldon|first=M.D.
 |coauthors=Saager, R.; Okishev, A.; Seka, W.
 |title=Thermal distortions in laser-diode- and flash-lamp-pumped Nd:YLF laser rods
 |journal=LLE Review|year=1997|volume=71
 |pages=137–144|url=http://www.lle.rochester.edu/pub/review/v71/6_thermal.pdf
 |accessdate=2007-02-04 |format=PDF| archiveurl = http://web.archive.org/web/20031016171340/http://www.lle.rochester.edu/pub/review/v71/6_thermal.pdf| archivedate = October 16, 2003}}</ref>

[[Image:Xenon short arc 1.jpg|thumb|Xenon short-arc lamp|alt=Elongated glass sphere with two metal rod electrodes inside, facing each other. One electrode is blunt and another is sharpened.]]
[[Image:Xenon discharge tube.jpg|thumb|Xenon gas discharge tube]]
Continuous, short-arc, high pressure [[xenon arc lamp]]s have a [[color temperature]] closely approximating noon sunlight and are used in solar simulators. That is, the [[chromaticity]] of these lamps closely approximates a heated [[black body]] radiator that has a temperature close to that observed from the Sun. After they were first introduced during the 1940s, these lamps began replacing the shorter-lived [[carbon arc lamp]]s in movie projectors.<ref name="mellor">{{cite book
 |first=David|last=Mellor|year=2000|page=186
 |title=Sound Person's Guide to Video
 |publisher=Focal Press
 |isbn=0240515951|url=http://books.google.com/?id=g93XXNA8Wf4C&pg=PA186}}</ref> They are employed in typical [[35 mm film|35mm]] and [[IMAX]] [[Movie projector|film projection]] systems, automotive [[High-intensity discharge lamp|HID]] headlights and other specialized uses. These arc lamps are an excellent source of short wavelength [[ultraviolet]] radiation and they have intense emissions in the near [[infrared]], which is used in some [[night vision]] systems.

The individual cells in a [[plasma display]] use a mixture of xenon and neon that is converted into a [[plasma (physics)|plasma]] using [[electrode]]s. The interaction of this plasma with the electrodes generates ultraviolet [[photon]]s, which then excite the [[phosphor]] coating on the front of the display.<ref>{{cite web
 |author=Anonymous
 |url=http://www.plasmatvscience.org/theinnerworkings.html
 |title=The plasma behind the plasma TV screen
 |publisher=Plasma TV Science|accessdate=2007-10-14}}</ref><ref>{{cite news
 |last=Marin|first=Rick|date=March 21, 2001
 |title=Plasma TV: That New Object Of Desire 
 |publisher=The New York Times|url=http://www.nytimes.com/2001/03/25/style/plasma-tv-that-new-object-of-desire.html?sec=&spon=
 |accessdate=2009-04-03}}</ref>

Xenon is used as a "starter gas" in [[Sodium vapor lamp|high pressure sodium lamps]]. It has the lowest [[thermal conductivity]] and lowest [[ionization potential]] of all the non-radioactive noble gases. As a noble gas, it does not interfere with the chemical reactions occurring in the operating lamp. The low thermal conductivity minimizes thermal losses in the lamp while in the operating state, and the low ionization potential causes the [[breakdown voltage]] of the gas to be relatively low in the cold state, which allows the lamp to be more easily started.<ref>{{cite book
|first = John|last = Waymouth|year = 1971
|title = Electric Discharge Lamps|publisher = The M.I.T. Press
|location = Cambridge, MA|isbn = 0262230488}}</ref>

====Lasers====
In 1962, a group of researchers at [[Bell Labs|Bell Laboratories]] discovered laser action in xenon,<ref>{{cite journal
 |first=C. K. N.|last=Patel|coauthors=Bennett Jr., W. R.; Faust, W. L.; McFarlane, R. A.
 |title=Infrared spectroscopy using stimulated emission techniques
 |volume=9|issue=3|date=August 1, 1962|pages=102–104
 |journal=Physical Review Letters
 |doi=10.1103/PhysRevLett.9.102}}</ref> and later found that the laser gain was improved by adding [[helium]] to the lasing medium.<ref>{{cite journal
 |first=C. K. N.|last=Patel
 |coauthors=Faust, W. L.; McFarlane, R. A.
 |title=High gain gaseous (Xe-He) optical masers
 |journal=Applied Physics Letters
 |volume=1|issue=4|pages=84–85|date=December 1, 1962
 |doi=10.1063/1.1753707
}}</ref><ref>{{cite journal
 |first=W. R.|last=Bennett, Jr.
 |title=Gaseous optical masers
 |journal=Applied Optics Supplement
 |volume=1|year=1962|pages=24–61}}</ref> The first [[excimer laser]] used a xenon [[Dimer (chemistry)|dimer]] (Xe<sub>2</sub>) energized by a beam of electrons to produce [[stimulated emission]] at an [[ultraviolet]] wavelength of 176 [[nanometre|nm]].<ref name="basov">{{cite journal
 |doi=10.1070/QE1971v001n01ABEH003011
 |last=Basov|first=N. G.
 |coauthors=Danilychev, V. A.; Popov, Yu. M.
 |title=Stimulated Emission in the Vacuum Ultraviolet Region
 |journal=Soviet Journal of Quantum Electronics
 |year=1971|volume=1|issue=1|pages=18–22}}</ref>
Xenon chloride and xenon fluoride have also been used in excimer (or, more accurately, exciplex) lasers.<ref>{{cite web
 |url=http://www.safetyoffice.uwaterloo.ca/hse/laser/documents/laser_types.html
 |title=Laser Output|publisher=University of Waterloo
 |accessdate=2007-10-07}}</ref> The xenon chloride excimer laser has been employed, for example, in certain dermatological uses.<ref>{{cite journal
 |doi=10.1111/j.1468-3083.2006.01495.x
 |first=E.|last=Baltás
 |coauthors=Csoma, Z.; Bodai, L.; Ignácz, F.; Dobozy, A.; Kemény, L.
 |title=Treatment of atopic dermatitis with the xenon chloride excimer laser
 |journal=Journal of the European Academy of Dermatology and Venereology
 |year=2006|volume=20|issue=6|pages=657–660
 |pmid=16836491}}</ref>

===Medical===
====Anesthesia====
Xenon has been used as a [[general anaesthetic]]. Although it is expensive, anesthesia machines that can deliver xenon are about to appear on the European market, because advances in recovery and recycling of xenon have made it economically viable.<ref name="singh" /><ref>{{cite journal|last=Tonner|first=P. H.|title=Xenon: one small step for anaesthesia…? (editorial review)|journal=Current Opinion in Anaesthesiology|year=2006|volume=19|issue=4|pages=382–384|doi=10.1097/01.aco.0000236136.85356.13|pmid=16829718}}</ref>

Two physiological mechanisms for xenon anesthesia have been proposed. The first one involves the inhibition of the [[Plasma membrane Ca2+ ATPase|calcium ATPase pump]]—the mechanism cells use to remove calcium (Ca<sup>2+</sup>)—in the [[cell membrane]] of [[Chemical synapse|synapses]].<ref name=Franks1995>{{Cite journal|last=Franks|first=JJ|coauthors=Horn JL, Janicki PK, Singh G|title=Halothane, isoflurane, xenon, and nitrous oxide inhibit calcium ATPase pump activity in rat brain synaptic plasma membranes|journal=Anesthesiology|volume=82|issue=1|pages=108–117|year=1995|pmid=7832292|doi=10.1097/00000542-199501000-00015|url=http://journals.lww.com/anesthesiology/fulltext/1995/01000/halothane,_isoflurane,_xenon,_and_nitrous_oxide.15.aspx#|accessdate=2010-09-15}}</ref> This results from a [[conformational isomerism|conformational change]] when xenon binds to nonpolar sites inside the protein.
<ref name=Lopez1995>{{Cite journal|last=Lopez|first=MM|coauthors=Kosk-Kosicka D|title=How do volatile anesthetics inhibit Ca<sub>2</sub><sup>+</sup>-ATPases?|journal=Journal of Biological Chemistry|volume=270|issue=47|pages=28239–28245|year=1995|pmid=7499320|doi=10.1074/jbc.270.47.28239|url=http://www.jbc.org/content/270/47/28239.full|accessdate=2010-09-15}}</ref> The second mechanism focuses on the non-specific interactions between the anesthetic and the [[Lipid bilayer|lipid membrane]].<ref name=Heimburg2007>{{Cite journal|last=Heimburg|first=T|coauthors=Jackson AD|title=The thermodynamics of general anesthesia|journal=Biophysical Journal|volume=92|issue=9|pages=3159–65|year=2007|pmid=17293400|pmc=1852341|doi=10.1529/biophysj.106.099754|url=http://www.cell.com/biophysj/retrieve/pii/S0006349507711244|accessdate=2010-09-15}}</ref>

Xenon has a [[minimum alveolar concentration]] (MAC) of 71%, making it 50% more potent than N<sub>2</sub>O as an anesthetic. Thus it can be used in concentrations with oxygen that have a lower risk of [[Hypoxia (medical)|hypoxia]]. Unlike [[nitrous oxide]] (N<sub>2</sub>O), xenon is not a [[greenhouse gas]] and so it is also viewed as [[environmentally friendly]].<ref name=Goto2003>{{Cite journal|last=Goto|first=T|coauthors=Nakata Y, Morita S|title=Will xenon be a stranger or a friend?: the cost, benefit, and future of xenon anesthesia|journal=Anesthesiology|volume=98|issue=1|pages=1–2|year=2003|pmid=12502969|url=http://journals.lww.com/anesthesiology/Fulltext/2003/01000/Will_Xenon_Be_a_Stranger_or_a_Friend___The_Cost,.2.aspx|accessdate=2010-09-15}}</ref> Xenon vented into the atmosphere is being returned to its original source, so no environmental impact is likely.

====Neuroprotectant====
Xenon is finding application in treating brain injuries, since it is an [[Receptor antagonist|antagonist]] of N-methyl-d-aspartate receptors ([[NMDA receptor]]s). These receptors exacerbate the damage from [[oxygen deprivation]] and xenon performs better as a [[neuroprotectant]] than either [[ketamine]] or [[nitrous oxide]], which have undesired side-effects.<ref>{{cite journal |last1=Ma |first1=D. |last2=Wilhelm |first2=S. |last3=Maze |first3=M. |last4=Franks |first4=N.P. |year=2002 |title=Neuroprotective and neurotoxic properties of the 'inert' gas, xenon |journal=British Journal of Anaesthesia |publisher=  |pmid=12393773|volume=89 |issue=5 |pages=739–746 |url=http://bja.oxfordjournals.org/cgi/content/abstract/89/5/739 |doi=10.1093/bja/aef258 }}</ref> Xenon gas was added as an ingredient of the [[Mechanical ventilation|ventilation mix]] for a newborn baby at [[St. Michael's Hospital, Bristol]], England, whose life chances were otherwise very compromised, and was successful, leading to the authorisation of [[clinical trial]]s for similar cases.<ref>{{cite web
 | title=First baby given xenon gas to prevent brain injury
 | work=BBC News | date=April 9, 2010
 | url=http://news.bbc.co.uk/1/hi/england/bristol/8611130.stm
 | accessdate=2010-04-09 }}</ref><ref>{{cite news|publisher=BBC|url=http://news.bbc.co.uk/2/hi/uk_news/england/bristol/somerset/8611130.stm|title=First baby given xenon gas to prevent brain injury|date=9 April 2010}}</ref>

====Imaging====
[[gamma ray|Gamma]] emission from the [[radioisotope]] <sup>133</sup>Xe of xenon can be used to image the heart, lungs, and brain, for example, by means of [[single photon emission computed tomography]]. <sup>133</sup>Xe has also been used to measure [[blood flow]].<ref>{{cite book
 |first=Ernst|last=Van Der Wall|year=1992
 |title=What's New in Cardiac Imaging?: SPECT, PET, and MRI
|publisher=Springer|isbn=0792316150|url=http://books.google.com/?id=PypZMUhqnK8C&pg=PA41
}}</ref><ref>{{cite journal
 |last=Frank|first=John
 |title=Introduction to imaging: The chest
 |journal=Student BMJ|year=1999|volume=12|pages=1–44
 |url=http://student.bmj.com/issues/04/01/education/8.php
 |accessdate=2008-06-04
}}</ref><ref>{{cite web
 |last=Chandak|first=Puneet K.|date=July 20, 1995
 |url=http://brighamrad.harvard.edu/education/online/BrainSPECT/Theory/Xenon133.html
 |title=Brain SPECT: Xenon-133|publisher=Brigham RAD
 |accessdate=2008-06-04}}</ref>

Xenon, particularly hyperpolarized <sup>129</sup>Xe, is a useful contrast agent for [[MRI|magnetic resonance imaging]] (MRI). In the gas phase, it can be used to image empty space such as cavities in a porous sample or alveoli in lungs. [[Hyperpolarization (physics)|Hyperpolarization]] renders <sup>129</sup>Xe much more detectable via [[magnetic resonance imaging]] and has been used for studies of the lungs and other tissues. It can be used, for example, to trace the flow of gases within the lungs.<ref>{{cite journal
 |last=Albert|first=M. S.|coauthors=Balamore, D.
 |title=Development of hyperpolarized noble gas MRI
 |journal=Nuclear Instruments and Methods in Physics Research A
 |year=1998|volume=402|pages=441–453
 |doi=10.1016/S0168-9002(97)00888-7
}}</ref><ref>{{cite news
 |last=Irion|first=Robert|date=March 23, 1999
 |title=Head Full of Xenon?|publisher=Science News
 |url=http://sciencenow.sciencemag.org/cgi/content/full/1999/323/3
 |accessdate=2007-10-08| archiveurl = http://web.archive.org/web/20040117194538/http://sciencenow.sciencemag.org/cgi/content/full/1999/323/3| archivedate = January 17, 2004}}</ref> Because xenon is soluble in water and also in hydrophobic solvents, it can be used to image various soft living tissues.<ref>{{cite journal
 |title=Intravascular delivery of hyperpolarized 129Xenon for in vivo MRI
 |journal= Applied Magnetic Resonance |volume=15|issue=3-4
 |year=1998|doi=10.1007/BF03162020
 |pages=343–352|author=Wolber, J. |coauthors=''et al.''}}</ref><ref>{{cite journal
 |pmid=19703880 |year=2009 |author=Driehuys, B.; Möller, H.E.; Cleveland, Z.I.; Pollaro, J.; Hedlund, L.W.;
 |title=Pulmonary perfusion and xenon gas exchange in rats: MR imaging with intravenous injection of hyperpolarized 129Xe
 |volume=252|ssue=2 |pages=386–93
 |doi=10.1148/radiol.2522081550|pmc=2753782
 |journal=Radiology
 |issue=2}}</ref><ref>{{cite journal
|pmid=19702286|year=2009
 |author=Cleveland, Z.I.; Möller, H.E.; Hedlund, L.W.; Driehuys, B.
 |title=Continuously infusing hyperpolarized 129Xe into flowing aqueous solutions using hydrophobic gas exchange membranes
 |volume=113 |issue=37 |pages=12489–99
 |doi=10.1021/jp9049582 |pmc=2747043
 |journal=The journal of physical chemistry}}</ref>

===NMR spectroscopy===
Because of the atom's large, flexible outer electron shell, the [[NMR]] spectrum changes in response to surrounding conditions, and can therefore be used as a probe to measure the chemical circumstances around the xenon atom. For instance xenon dissolved in water, xenon dissolved in hydrophobic solvent, and xenon associated with certain proteins can be distinguished by NMR.<ref>{{cite journal
 |journal=Magnetic Resonance in Chemistry |volume=27
 |issue=10 |pages=950 |doi=10.1002/mrc.1260271009
 |title=Interpretation of the solvent effect on the screening constant of Xe-129 |author=Luhmer, M.
 |coauthors=''et al.''
 |year=1989
}}</ref><ref>{{cite journal
 |author=Rubin, Seth M.; Spence, Megan M.; Goodson, Boyd M.; Wemmer, David E.; Pines, Alexander
 |title=Evidence of nonspecific surface interactions between laser-polarized xenon and myoglobin in solution
 |journal=Proceedings of the National Academy of Science USA
 |date=August 15, 2000 |volume=97
 |pmid=10931956 |issue=17
 |pmc=16888 |pages=9472–9475
 |doi=10.1073/pnas.170278897 |accessdate=2010-02-21}}</ref>

Hyperpolarized xenon can be used by [[Surface science|surface-chemists]]. Normally, it is difficult to characterize surfaces using NMR, because signals from the surface of a sample will be overwhelmed by signals from the far-more-numerous atomic nuclei in the bulk. However, nuclear spins on solid surfaces can be selectively polarized, by [[Proton Enhanced Nuclear Induction Spectroscopy|transferrering spin polarization to them]] from hyperpolarized xenon gas. This makes the surface signals strong enough to measure, and distinguishes them from bulk signals.<ref>{{cite journal
 |doi=10.1021/ja972035d |title=Optical Pumping and Magic Angle Spinning: Sensitivity and Resolution Enhancement for Surface NMR Obtained with Laser-Polarized Xenon
 |year=1997 |author=Raftery, Daniel; MacNamara, Ernesto; Fisher, Gregory; Rice, Charles V.; Smith, Jay
 |journal=Journal of the American Chemical Society
 |volume=119 |pages=8746
}}</ref><ref>{{cite journal
 |author=Gaede, H. C.; Song, Y. -Q.; Taylor, R. E.; Munson, E. J.; Reimer, J. A.; Pines, A.
 |doi=10.1007/BF03162652
 |title=High-field cross polarization NMR from laser-polarized xenon to surface nuclei
 |year=1995 |journal=Applied Magnetic Resonance
 |volume=8 |pages=373}}</ref>

===Other===
In [[nuclear energy]] applications, xenon is used in [[bubble chamber]]s,<ref>{{cite book
 |first=Peter Louis|last=Galison|year=1997
 |title=Image and Logic: A Material Culture of Microphysics
 |page=339|url=http://books.google.com/?id=HnRDiDtO5yoC&pg=PA339|publisher=University of Chicago Press|isbn=0226279170}}</ref> probes, and in other areas where a high [[Molecular mass|molecular weight]] and inert nature is desirable. A by-product of [[nuclear weapon]] testing is the release of radioactive xenon-133 and xenon-135. The detection of these isotopes is used to monitor compliance with
[[Test Ban Treaty|test ban treaties]],<ref>{{cite journal
 |author=Fontaine, J.-P.; Pointurier, F.; Blanchard, X.; Taffary, T.|title=Atmospheric xenon radioactive isotope monitoring|journal=Journal of Environmental Radioactivity
 |volume=72|issue=1–2|pages=129–135|year=2004
 |doi=10.1016/S0265-931X(03)00194-2
 |pmid=15162864}}</ref> as well as
to confirm nuclear test explosions by states such as [[North Korea]].<ref>{{cite journal
 |author=Garwin, Richard L.; von Hippel Frank N.
 |title=A Technical Analysis: Deconstructing North Korea's October 9 Nuclear Test|publisher=Arms Control Association 
 |journal=Arms Control Today|volume=38|issue=9
 |month=November|year=2006|accessdate=2009-03-26
 |url=http://www.armscontrol.org/act/2006_11/tech}}</ref>

[[Image:Xenon ion engine prototype.png|left|thumb|A prototype of a xenon ion engine being tested at NASA's Jet Propulsion Laboratory.|alt=A metal cylinder with electrodes attached to its side. Blue diffuse light is coming out of the tube.]]
Liquid xenon is being used as a medium for detecting hypothetical [[weakly interacting massive particles]], or WIMPs. When a WIMP collides with a xenon nucleus, it should, theoretically, strip an electron and create a primary [[Scintillation (physics)|scintillation]]. By using xenon, this burst of energy could then be readily distinguished from similar events caused by particles such as [[cosmic ray]]s.<ref name="ball">{{cite web
 |last=Ball|first=Philip|date=May 1, 2002
 |url=http://www.nature.com/news/2002/020429/full/news020429-6.html
 |title=Xenon outs WIMPs|publisher=Nature
 |accessdate=2007-10-08}}</ref> However, the XENON experiment at the [[Gran Sasso National Laboratory]] in Italy and the ZEPLIN-II and ZEPLIN-III experiments at the [[Boulby Underground Laboratory]] in the UK have thus far failed to find any confirmed WIMPs. Even if no WIMPs are detected, the experiments will serve to constrain the properties of [[dark matter]] and some physics models.<ref>{{cite web
 |last=Schumann|first=Marc|date=October 10, 2007
 |url=http://xenon.physics.rice.edu/
 |title=XENON announced new best limits on Dark Matter
 |publisher=Rice University|accessdate=2007-10-08
}}</ref><ref>{{cite journal
 |last=Lebedenko|first=V. N.|coauthors=''et al''.
 |title=Results from the first science run of the ZEPLIN-III dark matter search experiment
 |journal=Physical Review D|volume=80|issue=5
 |month=September|year=2009|doi=10.1103/PhysRevD.80.052010
 |bibcode=2009PhRvD..80e2010L
 |pages=052010
}}</ref> The current detector at the Gran Sasso facility has demonstrated sensitivity comparable to that of the best cryogenic detectors, and the sensitivity was expected to be increased by an [[order of magnitude]] in 2009.<ref>{{cite news
 |last=Boyd|first=Jade|date=August 23, 2007
 |title=Rice physicists go deep for 'dark matter'
 |publisher=Hubble News Desk
 |url=http://www.media.rice.edu/media/NewsBot.asp?MODE=VIEW&ID=9902&SnID=1256234278
 |accessdate=2007-10-08}}</ref>

Xenon is the preferred fuel for [[ion propulsion]] of [[spacecraft]] because of its low [[ionization potential]] per [[Atomic mass|atomic weight]], and its ability to be stored as a liquid at near [[room temperature]] (under high pressure) yet be easily converted back into a gas to fuel the engine. The inert nature of xenon makes it environmentally friendly and less corrosive to an [[ion engine]] than other fuels such as [[Mercury (element)|mercury]] or [[caesium]]. Xenon was first used for satellite ion engines during the 1970s.<ref>{{cite web
 |last=Zona|first=Kathleen|date=March 17, 2006
 |url=http://www.nasa.gov/centers/glenn/about/fs08grc.html
 |title=Innovative Engines: Glenn Ion Propulsion Research Tames the Challenges of 21st century Space Travel
 |publisher=NASA|accessdate=2007-10-04}}</ref> It was later employed as a propellant for Europe's [[SMART-1]] spacecraft<ref name="saccoccia">{{cite news
 |last=Saccoccia|first=G.
 |coauthors=del Amo, J. G.; Estublier, D.
 |title=Ion engine gets SMART-1 to the Moon
 |date=August 31, 2006|publisher=ESA
 |url=http://www.esa.int/SPECIALS/SMART-1/SEMLZ36LARE_0.html|accessdate=2007-10-01}}</ref> and for the three ion propulsion engines on NASA's [[Dawn Spacecraft]].<ref>{{cite web
 |url=http://www.jpl.nasa.gov/news/press_kits/dawn-launch.pdf|format=PDF
 |title=Dawn Launch: Mission to Vesta and Ceres
 |publisher=NASA|accessdate=2007-10-01}}</ref>

Chemically, the [[perxenate]] compounds are used as [[oxidizing agent]]s in [[analytical chemistry]]. [[Xenon difluoride]] is used as an etchant for [[silicon]], particularly in the production of [[microelectromechanical systems]] (MEMS).<ref>{{cite conference
 |last=Brazzle|first=J. D.
 |coauthors=Dokmeci, M. R.; Mastrangelo, C. H.
 |title=Modeling and Characterization of Sacrificial Polysilicon Etching Using Vapor-Phase Xenon Difluoride
|booktitle=Proceedings 17th IEEE International Conference on Micro Electro Mechanical Systems (MEMS)
 |pages=737–740
 |publisher=IEEE
 |date=July 28-August 1, 1975
 |location=Maastricht, Netherlands
 |isbn=9780780382657}}</ref> The anticancer drug [[Fluorouracil|5-fluorouracil]] can be produced by reacting xenon difluoride with [[uracil]].<ref>{{cite web
 |author=Staff|year=2007
 |url=http://acswebcontent.acs.org/landmarks/bartlett/tool.html
 |title=Powerful tool|publisher=American Chemical Society
 |accessdate=2007-10-10}}</ref> Xenon is also used in [[X-ray crystallography|protein crystallography]]. Applied at pressures from 0.5 to 5&nbsp;[[Pascal (unit)|MPa]] (5 to 50&nbsp;[[atmosphere (unit)|atm]]) to a protein crystal, xenon atoms bind in predominantly [[Hydrophobe|hydrophobic]] cavities, often creating a high quality, isomorphous, heavy-atom derivative, which can be used for solving the [[phase problem]].<ref>{{cite web
 |author=Staff|date=December 21, 2004
 |url=http://www.srs.ac.uk/px/facilities/xenon_notes_1.html
 |title=Protein Crystallography: Xenon and Krypton Derivatives for Phasing 
 |publisher=Daresbury Laboratory, PX
 |accessdate=2007-10-01
}}</ref><ref>{{cite book
 |first=Jan|last=Drenth|coauthors=Mesters, Jeroen
 |chapter=The Solution of the Phase Problem by the Isomorphous Replacement Method
 |pages=123–171|doi=10.1007/0-387-33746-6_7
 |title=Principles of Protein X-Ray Crystallography
 |publisher=Springer|location=New York
 |isbn= 978-0-387-33334-2|edition=3rd
 |year=2007}}</ref>
<div style="clear:both;"></div>

==Precautions==
Many oxygen-containing [[xenon compounds]] are toxic due to their strong [[oxidation|oxidative]] properties, and explosive due to their tendency to break down into elemental xenon plus diatomic oxygen (O<sub>2</sub>), which contains much stronger chemical bonds than the xenon compounds.<ref name="finkel68">{{cite web
 |last=Finkel|first=A. J.
 |coauthors=Katz, J. J.; Miller, C. E.
 |date=April 1, 1968 
 |url=http://ntrs.nasa.gov/search.jsp?R=306918&id=2&qs=No%3D40%26Ne%3D26%26N%3D297%2B140%26Ns%3DPublicationYear%257C0
 |title=Metabolic and toxicological effects of water-soluble xenon compounds are studied 
 |publisher=NASA|accessdate=2007-10-04}}</ref>

Xenon gas can be safely kept in normal sealed glass or metal containers at [[standard temperature and pressure]]. However, it readily dissolves in most plastics and rubber, and will gradually escape from a container sealed with such materials.<ref>{{
cite journal
 |last=LeBlanc|first=Adrian D.
 |coauthors=Johnson, Philip C.
 |title=The handling of xenon-133 in clinical studies
 |year=1971|journal=Physics in Medicine and Biology
 |volume=16|issue=1|pages=105–109
 |doi=10.1088/0031-9155/16/1/310 
 |pmid=5579743}}</ref> Xenon is non-[[toxic]], although it does dissolve in blood and belongs to a select group of substances that penetrate the [[blood-brain barrier]], causing mild to full surgical [[anesthesia]] when inhaled in high concentrations with oxygen.<ref name="finkel68" />

At 169&nbsp;m/s, the [[speed of sound]] in xenon gas is slower than that in air<ref>169.44&nbsp;m/s in xenon (at 0°C and 107&nbsp;KPa), compared to 344&nbsp;m/s in air. See: {{cite journal
 |last=Vacek|first=V.
 |coauthors=Hallewell, G.; Lindsay, S.
 |title=Velocity of sound measurements in gaseous per-fluorocarbons and their mixtures
 |journal=Fluid Phase Equilibria
 |year=2001|volume=185|pages=305–314
 |doi = 10.1016/S0378-3812(01)00479-4}}</ref> due to the slower average speed of the heavy xenon atoms compared to nitrogen and oxygen molecules. Hence, xenon lowers the resonant frequencies of the [[vocal tract]] when inhaled. This produces a characteristic lowered voice timbre, an effect opposite to the high-timbred voice caused by inhalation of [[helium]]. Like helium, xenon does not satisfy the body's need for oxygen. Xenon is both a simple [[asphyxiant gas|asphyxiant]] and an anesthetic more powerful than nitrous oxide; consequently, many universities no longer allow the voice stunt as a general chemistry demonstration. As xenon is expensive, the gas [[sulfur hexafluoride]], which is similar to xenon in molecular weight (146 versus 131), is generally used in this stunt, and is an asphyxiant without being anesthetic.<ref>{{cite web
 |first=Steve|last=Spangler|year=2007
 |url=http://www.stevespanglerscience.com/experiment/from-donald-duck-to-barry-white-how-gases-change-your-voice
 |title=Anti-Helium - Sulfur Hexafluoride 
 |publisher=Steve Spangler Science
 |accessdate=2007-10-04}}</ref>

It is possible to safely breathe heavy gases such as xenon or sulfur hexafluoride when they include a 20% mixture of oxygen. Although xenon at this concentration would be expected to rapidly produce the unconsciousness of general anesthesia, the lungs mix the gases very effectively and rapidly so that the heavy gases are purged along with the oxygen and do not accumulate at the bottom of the lungs.<ref>{{cite journal
 |last=Yamaguchi|first=K.
 |coauthors=Soejima, K.; Koda, E.; Sugiyama, N
 |title=Inhaling Gas With Different CT Densities Allows Detection of Abnormalities in the Lung Periphery of Patients With Smoking-Induced COPD
 |journal=Chest Journal
 |year=2001|volume=51|pages=1907–1916
 |doi= 10.1378/chest.120.6.1907|pmid=11742921|issue=6}}</ref> There is, however, a danger associated with any heavy gas in large quantities: it may sit invisibly in a container, and if a person enters a container filled with an odorless, colorless gas, they may find themselves breathing it unknowingly. Xenon is rarely used in large enough quantities for this to be a concern, though the potential for danger exists any time a tank or container of xenon is kept in an unventilated space.<ref>{{cite web
 |author=Staff|date=August 1, 2007
 |url=http://www-group.slac.stanford.edu/esh/hazardous_substances/cryogenic/p_hazards.htm
 |title=Cryogenic and Oxygen Deficiency Hazard Safety
 |publisher=Stanford Linear Accelerator Center
 |accessdate=2007-10-10| archiveurl = http://web.archive.org/web/20070609173316/http://www-group.slac.stanford.edu/esh/hazardous_substances/cryogenic/p_hazards.htm| archivedate = June 9, 2007}}</ref>

==See also==
*[[Buoyant levitation]]
*[[Penning mixture]]

==References==
{{reflist|2}}

==External links==
{{Commons|Xenon}}
{{wiktionary|xenon}}
*[http://www.webelements.com/webelements/elements/text/Xe/index.html WebElements.com – Xenon]
*[http://wwwrcamnl.wr.usgs.gov/isoig/period/xe_iig.html USGS Periodic Table - Xenon]
*[http://environmentalchemistry.com/yogi/periodic/Xe.html EnvironmentalChemistry.com - Xenon]
*[http://www.anaesthetist.com/anaes/drugs/xenon.htm Xenon as an anesthetic]
*[http://nobelprize.org/nobel_prizes/chemistry/laureates/1904/ramsay-lecture.html Sir William Ramsay's Nobel-Prize lecture (1904)]

{{clear}}
{{compact periodic table}}
{{Xenon compounds}}

{{featured article}}

[[Category:Xenon]]
[[Category:Noble gases]]
[[Category:Chemical elements]]
[[Category:General anesthetics]]
[[Category:NMDA receptor antagonists]]

{{Link FA|sv}}
{{Link FA|de}}
<!-- interwiki -->
[[af:Xenon]]
[[ar:زينون]]
[[az:Ksenon]]
[[bn:জেনন]]
[[be:Ксенон]]
[[be-x-old:Ксэнон]]
[[bs:Ksenon]]
[[bg:Ксенон]]
[[ca:Xenó]]
[[cv:Ксенон]]
[[cs:Xenon]]
[[co:Xenu]]
[[cy:Senon]]
[[da:Xenon]]
[[de:Xenon]]
[[et:Ksenoon]]
[[el:Ξένο]]
[[es:Xenón]]
[[eo:Ksenono]]
[[eu:Xenon]]
[[fa:زنون]]
[[fr:Xénon]]
[[fur:Xenon]]
[[ga:Xeanón]]
[[gv:Xenon]]
[[gl:Xenon]]
[[xal:Ксенөн]]
[[ko:제논 (원소)]]
[[hy:Քսենոն]]
[[hi:ज़ेनान]]
[[hr:Ksenon]]
[[io:Xenono]]
[[id:Xenon]]
[[is:Xenon]]
[[it:Xeno]]
[[he:קסנון]]
[[kn:ಝೆನಾನ್]]
[[sw:Xenoni]]
[[la:Xenon]]
[[lv:Ksenons]]
[[lb:Xenon]]
[[lt:Ksenonas]]
[[lij:Seno]]
[[li:Xenon]]
[[jbo:fangynavni]]
[[hu:Xenon]]
[[ml:സെനൊൺ]]
[[mr:झेनॉन]]
[[ms:Xenon]]
[[nl:Xenon]]
[[ja:キセノン]]
[[no:Xenon]]
[[nn:Xenon]]
[[oc:Xenon]]
[[uz:Ksenon]]
[[nds:Xenon]]
[[pl:Ksenon]]
[[pt:Xenônio]]
[[ro:Xenon]]
[[qu:Senun]]
[[ru:Ксенон]]
[[stq:Xenon]]
[[scn:Xenu]]
[[simple:Xenon]]
[[sk:Xenón]]
[[sl:Ksenon]]
[[sr:Ксенон]]
[[sh:Ksenon]]
[[fi:Ksenon]]
[[sv:Xenon]]
[[tl:Henon (elemento)]]
[[ta:செனான்]]
[[th:ซีนอน]]
[[tr:Ksenon]]
[[uk:Ксенон]]
[[ur:زینون]]
[[ug:كسېنون]]
[[vi:Xenon]]
[[war:Xenon]]
[[yo:Xenon]]
[[zh-yue:氙]]
[[zh:氙]]
[[Category:2Fix]]