Shopping on line can be easy, simple and save you lots of money. It can also take a lot of your time, frustrate you, and result in unwanted purchases. Now the same can be said for regular high street shopping, but with the vast opportunity presented by the Internet it will pay you to spend a few minutes reading this and understanding how to better optimize your Xenon shopping experience:
1. Compare - without doubt the biggest advantage that the Xenon offers shoppers today is the ability to compare thousands of Xenon at a time. This is a great thing, but not necessarily all the time! Too much can be daunting at times so take advantage of the great comparison sites and where possible let them do the hard work for you.
2. Research - if it has been said it will be on the internet. Ignorance is no longer a justifiable reason for buying the wrong thing. Take the time to research in detail everything that you could possible want to know about
3. Testimonials - don't know anybody that has bought a Xenon? Wrong! If the Xenon is good the internet will let you know. Use the Internet as a friend and get testimonials before you buy.
4. Questions - Got a question about Xenon then search the Forums, FAQ's, Blogs etc. Don't be afraid to ask .....
5. Reputation - Never heard of the company selling Xenon? Don't worry, no reason why you should know every company in the world, but you know someone that does! Use the internet to find out what people are saying about Xenon and build up a picture of their reputation for sales, returns, customer service, delivery etc.
6. Returns - still worried that even after all of the above your Xenon wont be what you want? Check out the returns policy. There is so much competition now that someone, somewhere is bound to offer the terms that you are comfortable with.
7. Feedback - happy with your Xenon then let people know, after all you are depending on others people input in your buying decision, so why not give a little back.
8. Security - check for the yellow padlock on the Xenon site before you buy, and the s after http:/ /i.e. https:// = a secure site
9. Contact - got a question about Xenon, or want to leave a comment then check out the sites contact page. Reputable companies have them and respond.
10. Payment - ready to pay for your Xenon, then use your credit card or PayPal! Be aware of companies that don't accept them, there may be genuine reasons but given the huge amount of choice you have when buying online there is no reason at all not to buy via credit card or PayPal.
{{Elementbox_triplepoint | k=161.405 | pa=81.6 k| comment=-->{{Elementbox_isotopes_decay | mn=125 | sym=Xe| na=[synthetic radioisotope | hl=16.9 [hour
| dm=[electron capture | de=1.652 | pn=125 | ps=[iodine -->
{{Elementbox_isotopes_decay | mn=127 | sym=Xe| na=[synthetic radioisotope | hl=36.345 [day
| dm=[electron capture | de=0.662 | pn=127 | ps=[iodine -->
{{Elementbox_isotopes_decay | mn=133 | sym=Xe| na=[synthetic radioisotope | hl=5.247 [day
| dm=[beta emission | de=0.427 | pn=133 | ps=[caesium -->
{{Elementbox_isotopes_decay | mn=135 | sym=Xe| na=[synthetic radioisotope | hl=9.14 [hour
| dm=[beta emission | de=1.16 | pn=135 | ps=[caesium-->
Xenon (
International Phonetic Alphabet: ) is a chemical element that has the symbol
Xe and
atomic number 54. A colorless, heavy, odorless noble gas, xenon occurs in the earth's atmosphere in trace amounts. Although generally unreactive, xenon can undergo a few chemical reactions such as the formation of xenon hexafluoroplatinate, the first noble gas compound to be synthesized.{{cite web,
| url=http://periodic.lanl.gov/elements/54.html | title=Xenon
| publisher=Los Alamos National Laboratory, Chemical Division
| accessdate=2007-09-26
-->{{cite book| last=Rabinovich | first=Viktor Abramovich
| coauthors=Vasserman, A. A.; Nedostup, V. I.; Veksler, L. S.
| year=1988
| title=Thermophysical properties of neon, argon, krypton, and xenon
| edition=English-language edition
| publisher=Hemisphere Publishing Corp.
| location=Washington, DC | id=ISBN 0195218337
| url=http://adsabs.harvard.edu/abs/1988wdch...10.....R -->—National Standard Reference Data Service of the USSR. Volume 10.
Naturally occurring xenon is made of Isotopes of xenon, but there are also over 40 unstable isotopes that undergo radioactive decay. Xenon is produced during
supernova explosions and from the radioactive decay of elements such as
iodine,
uranium and
plutonium. The isotope ratios of xenon are an important tool for studying the early history of the Solar System. Xenon-135 is produced as a result of nuclear fission and acts as a
neutron absorber in
nuclear reactors.
Xenon has many uses such as in xenon lamps and as a general anesthetic. The first
excimer laser design used a xenon
dimer molecule (Xe2) as its lasing medium, and the earliest laser designs used
xenon flash lamps as pumps. Xenon is also being used to search for hypothetical WIMP and as the propellant for ion thrusters in
spacecraft.
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.{{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 --> Sir Ramsay suggested the name xenon for this gas from the
Greek language word ''ξένον'' [xenon, neuter singular form of ''ξένος''
xenos, meaning foreign, strange, or host.{{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 | pages=p. 906
-->{{cite book| author=Staff | year=1991
| title=The Merriam-Webster New Book of Word Histories
| pages=p. 513 | publisher=Merriam-Webster, Inc.
| id=ISBN 0877796033 --> In 1902, Sir Ramsay estimated the proportion of xenon in the Earth's atmosphere as one part in 20 million.
During the 1930s, the engineer Harold Edgerton began exploring strobe light technology for
high-speed photography. In 1934 he pushed the time resolution down to a millionth of a second by creating an electrical spark inside a gas tube filled with xenon gas. By this means he invented the
xenon flash lamp.
Albert R. Behnke Jr. began exploring the causes of 'drunkenness' of deep-sea divers in 1939. 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 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.
In 1960, the physicist
John Reynolds discovered that certain meteorites 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. As the half-life of 129I is16 million years, this demonstrated that the meteorites were formed during the early history of the
Solar System, as the 129I isotope was likely generated by one or more
supernovae before the Solar System was formed.{{cite book| first=Donald D. | last=Clayton | year=1983
| title=Principles of Stellar Evolution and Nucleosynthesis
| pages=p. 75 | edition=2nd edition
| publisher=University of Chicago Press | id=ISBN 0226109534 -->
{{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 -->
Xenon and the other noble gases were for a long time considered to be completely chemically inert and not able to form chemical compounds. However, in 1962 at the University of British Columbia, the first xenon compound,
xenon hexafluoroplatinate, was synthesized by Neil Bartlett.{{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, [ |publisher=Chemical & Engineering News-->
Occurrence
Xenon is a trace gas in Earth's atmosphere, occurring at 0.087±0.001 parts per million (μL/L).{{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 edition
| doi=10.1002/0471238961.0701190508230114.a01.pub2
| isbn=047148511X --> It is also found in gases emitted from some [mineral springs. Radioactive species of xenon, for example, 133Xe and 135Xe, are produced by [neutron irradiation of fissionable material within [nuclear reactors.
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.{{cite book| first=Frank G. | last=Kerry | year=2007
| title=Industrial Gas Handbook: Gas Separation and Purification
| pages=pp. 101–103 | publisher=CRC Press
| id=ISBN 0849390052 -->
{{cite web| url=http://www.c-f-c.com/specgas_products/xenon.htm
| title=Xenon - Xe | accessdate=2007-09-07
|date=August 10, [ | publisher=CFC StarTec LLC
--> Extraction of a liter of xenon from the atmosphere requires 220 watt-hoursof energy.{{cite web,
| url=http://www.expresshealthcaremgmt.com/20050515/criticare10.shtml
| title=Xenon: A modern anaesthetic
| publisher=Indian Express Newspapers Limited
| accessdate=2007-10-10 --> Worldwide production of xenon in 1998 was estimated at 5000–7000 m³.{{cite book
| last=Häussinger | first=Peter
| coauthors=Reinhard Glatthaar, Wilhelm Rhode,
Helmut Kick, Christian Benkmann, Josef Weber, Hans-Jörg Wunschel,Viktor Stenke, Edith Leicht, Hermann Stenger| chapter=Noble Gases
| title=Ullmann's Encyclopedia of Industrial Chemistry
| publisher=Wiley | year=2001 | edition=6th edition
| doi=10.1002/14356007.a17_485 | isbn=3527201653 --> Due to 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 [Euro/L for xenon, 1 €/L for krypton, and 0.20 €/L for neon.
Xenon is relatively rare in the
Sun's atmosphere, on
Earth, and in the asteroids and
comets. The atmosphere of Mars shows a similar xenon abundance to that of Earth:0.08 parts per million.{{cite web,
| url=http://nssdc.gsfc.nasa.gov/planetary/factsheet/marsfact.html
| title=Mars Fact Sheet | publisher=NASA
| accessdate=2007-10-10 --> However, Mars shows a higher proportion of 129Xe 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.{{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 -->
By contrast, the planet Jupiter has an unusually high abundance of xenon in its atmosphere; about 2.6 times as much as the Sun. This high abundance remains unexplained, but may have been caused by an early and rapid buildup of [planetesimals—small, subplanetary bodies—before the solar nebula began to heat up. (Otherwise, xenon would not have been trapped in the planetesimal ices.) Within the [Solar System, the [nucleon fraction for all isotopes of xenon is 1.56×10-8, or one part in 64 million of the total mass.{{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 --> The problem of the low terrestrial xenon may potentially be explained by [covalent bonding of xenon to oxygen within [quartz, hence reducing the outgassing of xenon into the atmosphere.
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 to create xenon.{{cite book| first=Donald D. | last=Clayton | year=1983
| title=Principles of Stellar Evolution and Nucleosynthesis
| publisher=University of Chicago Press
| id=ISBN 0226109534 --> Instead, many isotopes of xenon are formed during [supernova explosions.{{cite conference
| author=Heymann, D.; Dziczkaniec, M.
| title =Xenon from intermediate zones of supernovae
| booktitle =Proceedings 10th Lunar and Planetary Science Conference
| pages =pp. 1943-1959
| publisher = Pergamon Press, Inc.
| date = March 19-23, 1979
| location = Houston, Texas
| url = http://adsabs.harvard.edu/abs/1976IAUS...73...75P
| accessdate = 2007-10-02
-->
Characteristics
An atom of xenon is defined as having a nucleus with 54 protons. At standard temperature and pressure, pure xenon gas has a density of 5.761 kg/m3, about 4.5 times the surface density of the Earth's atmosphere, 1.217 kg/m3.{{cite web,
| url=http://nssdc.gsfc.nasa.gov/planetary/factsheet/earthfact.html
| title=Earth Fact Sheet | publisher=NASA
| accessdate=2007-10-04 --> As a liquid, xenon has a density of 3.52 g/mL, about 3.5 times the density of water. The density of solid xenon, 2.7 g/cm3, is only slightly below the average density of [granite, 2.75 g/cm3.{{cite book
| first=Pradyot | last=Patnaik | year=2003
| title=Handbook of Inorganic Chemicals
| publisher=McGraw-Hill Professional | id=ISBN 0070494398 --> Using [pascal (unit)s of [pressure, xenon has been forced into a metallic phase.
Xenon is a member of the zero-valency (chemistry) elements that are called noble gas or
inert gases. It is inert to most common chemical reactions (such as combustion, for example) because the outer
valence shell is completely filled with eight electrons. This produces a stable, minimum energy configuration in which the outer electrons are tightly bound.{{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 --> However, xenon can be [Oxidation by powerful oxidizing agents, and multiple compounds of this noble gas have been synthesized.
In a gas-filled tube, xenon emits a blue glow when the gas is excited by electrical discharge. Xenon emits a band of emission lines that span the visual spectrum,{{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 -->
but the most intense lines occur in the region of blue light, which produces the coloration.{{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 -->
Isotopes
Naturally occurring xenon is made of nine stable isotope
isotopes. (124Xe, 134Xe and 136Xe are predicted to undergo double beta decay, but this has never been observed, so they are considered to be stable.){{cite web| last=Lüscher | first=Roland | year=2006
| url=http://www.shef.ac.uk/physics/bus2006/talks/luscher_roland.pdf
| title=Status of ßß-decay in Xenon
| publisher=University of Sheffield
| accessdate=2007-10-01 -->
Besides these stable forms, there are over 40 unstable isotopes that have been studied. 129Xe is produced by [beta decay of 129[iodine ([half-life: 16 million years); 131mXe, 133Xe, 133mXe, and 135Xe are some of the [nuclear fission products of both 235[uranium and 239[plutonium,{{cite web
| last=Caldwell | first=Eric | date=January 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 --> and therefore used as indicators of nuclear explosions.
The artificial isotope Xenon-135 is of considerable significance in the operation of nuclear reactor. 135Xe has a huge neutron cross section for
thermal neutrons, 2.6×106 Barn (unit),{{cite book| first=Weston M. | last=Stacey | year=2007
| title=Nuclear Reactor Physics | pages=p. 213
| publisher=Wiley-VCH | id=ISBN 3527406794 --> so it acts as a [neutron absorber or "[nuclear 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).{{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 -->
Relatively high concentrations of radioactive xenon isotopes are also found emanating from nuclear reactors due to the release of this fission gas from cracked fuel rods{{cite book| first=Edwards A. | last=Laws | year=2000
| title=Aquatic Pollution: An Introductory Text
| pages=p. 505 | publisher=John Wiley and Sons
| id=ISBN 0471348759 --> or fissioning of uranium in cooling water.{{cite news
| author=Staff | date=
April 9, [
| title=A Nuclear Nightmare | publisher=Time
| url=http://www.time.com/time/magazine/article/0,9171,920196-4,00.html
| accessdate=2007-10-09 --> The concentrations of these isotopes are still usually low compared to naturally occurring radioactive noble gases such as [radon-222.A typical boiling-water nuclear reactor releases about 13,000 [Curie of 133Xe per year.
In a typical indoor environment, radon concentration is about 200 pCi/L.
{{cite web
|author=Staff
| date=
June 16, [
| url=http://www.ccohs.ca/oshanswers/phys_agents/radon.html
| title=Radon in Buildings
| publisher=Canadian Centre for Occupational Health & Safety
| accessdate=2007-10-13
-->Thus an equivalent level of radioactivity from radon-222 would occupy:
\begin{smallmatrix} \frac{1.3 \times 10^4 \text{Ci-->{2.0 \times 10^{-10} \text{Ci/L--> = 6.5 \times 10^{14} L \end{smallmatrix}
or only 650 km3. Compare, for example, to the surface area of the
Earth, 5×108 km2, while looking at the first kilometer thickness of the atmosphere.
Because xenon is a tracer for two parent isotopes, xenon isotope ratios in
meteorites are a powerful tool for studying the
formation of the solar system. The iodine-xenon method of Radiometric dating gives the time elapsed between nucleosynthesis and the condensation of a solid object from the solar nebula. Xenon isotopic ratios such as 129Xe/130Xe and 136Xe/130Xe are also a powerful tool for understanding terrestrial differentiation and early outgassing. Excess 129Xe found in [carbon dioxide well gases from [New Mexico was believed to be from the decay of [Mantle (geology)-derived gases soon after Earth's formation.
Compounds
The first chemical compound of xenon, xenon hexafluoroplatinate, was synthesized in 1962. Now, many compounds of xenon are known, including xenon difluoride (XeF2),
xenon tetrafluoride (XeF4), xenon hexafluoride (XeF6), xenon tetroxide (XeO4), and
sodium perxenate (Na4XeO6). A highly
explosive compound
xenon trioxide (XeO3) has also been made. Most of the more than 80{{cite web| url=http://www.chemnetbase.com/periodic_table/elements/xenon.htm
| title=Xenon | publisher=CRC Press
| accessdate=2007-10-08 --> xenon compounds found to date contain electro-negative fluorine or oxygen. When other atoms are bound (such as [hydrogen or [carbon), they are often part of a molecule containing fluorine or oxygen.{{cite book
| author=Harding, Charlie J.; Janes, Rob | year=2002
| title=Elements of the P Block
| publisher=Royal Society of Chemistry
| id=ISBN 0854046909 --> Some compounds of xenon are [colored but most are colorless.
Recently, at the University of Helsinki in Finland, a group of scientists (M. Räsänen
et al.) prepared xenon dihydride (HXeH), xenon hydride-hydroxide (HXeOH), and hydroxenoacetylene (HXeCCH). They are stable up to 40
kelvin.See the paragraph starting ''Many recent findings'' in [Deuterium molecules, HXeOD and DXeOH, have also been produced.
As well as compounds where xenon forms a chemical bond, xenon can form
clathrates, such as
xenon hydrate (Xe·5.75 H2O), where xenon atoms occupy vacancies in a lattice of water molecules.A molecular theory of general anesthesia, Linus Pauling,
Science 134, #3471 (
July 7, 1961), pp. 15–21. Reprinted as pp. 1328–1334,
Linus Pauling: Selected Scientific Papers, vol. 2, edited by Barclay Kamb et al. River Edge, New Jersey: World Scientific: 2001, ISBN 9810229402. The
deuterated version of this hydrate has also been produced. Clathrate formation can be used to fractionally distill xenon, argon and krypton.
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 129Xe nuclear magnetic resonance 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.
Applications
Although xenon is rare and relatively expensive to extract from the Earth' atmosphere, it still has a number of useful commercial applications.
Illumination and optics
.Xenon is used in light-emitting devices called
xenon flash lamps, which are used in
photographic flashes and stroboscopic lamps;{{cite book| first=James | last=Burke | year=2003
| title=Twin Tracks: The Unexpected Origins of the Modern World
| publisher=Oxford University Press
| id=ISBN 0743226194 --> to excite the [active laser medium in [lasers which then generate [coherent light;{{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 --> to produce laser power for [inertial confinement fusion and rarely in [bactericidal lamps.
Continuous, short-arc, high pressure
xenon arc lamps have a color temperature closely approximating noon sunlight and are used in solar simulators. After they were first introduced during the 1940s, these lamps began replacing the shorter-lived carbon arc lamps in movie projectors.{{cite book| first=David | last=Mellor | year=2000 | pages=p. 186
| title=Sound Person's Guide to Video
| publisher=Focal Press | id=ISBN 0240515951 --> They are employed in typical [35mm and [IMAX film projection systems, automotive [High-intensity discharge lamp 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 using
electrodes. The interaction of this plasma with the electrodes generates ultraviolet
photons, which then excite the phosphor coating on the front of the display.{{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 -->{{cite news
| last=Marin | first=Rick | date=
March 21, [
| title=Plasma TV: That New Object Of Desire
| publisher=The New York Times -->
The first solid-state laser, invented in 1960, was pumped by a xenon flashlamp.{{cite book| author=Toyserkani, E.; Khajepour, A.; Corbin, S.
| year=2004 | title=Laser Cladding
| publisher=CRC Press | id=ISBN 0849321727 -->
Bell laboratories later developed the high-gain helium-xenon (HeXe) gas laser.{{cite book| first=Joan Lisa | last=Bromberg
| year=1991 | title=The laser in America, 1950-1970
| publisher=MIT Press
| location=Cambridge, Mass.
| id=ISBN 0262023180 --> A year afterward, the xenon laser was developed; it was among the first gas lasers discovered. This laser has a very high gain, but is only capable of producing low power levels with saturation at several microwatts.{{cite conference
| first = L. W. | last = Casperson
| title = Gas Laser Instabilities and their Interpretation
| booktitle = Proceedings of a NATO Advanced Study Institute on Instabilities and Chaos in Quantum Optics
| publisher = Springer | date = June 28-July 7, 1987
| location = Ciocco, Italy | id = ISBN 0306429144 --> The first [excimer laser used a xenon [dimer (Xe2) energized by a beam of electrons to produce stimulated emission at an [ultraviolet wavelength of 172 [nanometre.
Xenon chloride and xenon fluoride have also been used in excimer (or, more accurately, exciplex) lasers.{{cite web| url=http://www.rstp.uwaterloo.ca/laser/documents/laser_types.html
| title=Laser Output | publisher=University of Waterloo
| accessdate=2007-10-07 --> The xenon chloride excimer laser has been employed, for example, in certain dermatological uses.
Anesthesia
Xenon has been used as a general anesthetic, although it is expensive. As of 2005, the cost of 99.99% pure xenon gas is United States dollar10 per liter. Even so, anesthesia machines that can deliver xenon are about to appear on the European market. Two mechanisms for xenon anesthesia have been proposed. The first one involves the inhibition of the [Plasma membrane Ca2+ ATPase—the mechanism cells use to remove calcium (Ca2+)—in the [cell membrane of [Chemical synapse. This results from a [conformational isomerism when xenon binds to nonpolar sites inside the protein. The second mechanism focuses on the non-specific interactions between the anesthetic and the [Lipid bilayer.
Xenon has a minimum alveolar concentration (MAC) of 0.63, making it 50% more potent than N2O as an anesthetic. Thus it can be used in concentrations with oxygen that have a lower risk of
hypoxia. Unlike nitrous oxide (N2O), xenon is not a greenhouse gas and so it is also viewed as environmentally friendly. Because of the high cost of xenon, however, economic application will require a closed system so that the gas can be recycled.
Medical imaging
gamma ray emission from the radioisotope 133Xe of xenon can be used to image the heart, lungs, and brain, for example, by means of
single photon emission computed tomography. 133Xe has also been used to measure blood flow.{{cite book| first=Ernst | last=Van Der Wall | year=1992
| title=What's New in Cardiac Imaging?: SPECT, PET, and MRI
| publisher=Springer | id=ISBN 0792316150 -->
http://student.bmj.com/issues/04/01/education/8.php Introduction to imaging: The chest, John Frank, ''studentBMJ'' '''12''' (February 2004), pp. 1–44. Accessed on line
October 19, [.http://brighamrad.harvard.edu/education/online/BrainSPECT/Theory/Xenon133.html Brain SPECT: Xenon-133. Accessed on line October 19, [.
When it is placed in the presence of an
alkali vapor, the nucleus of the
Spin (physics) isotope 129Xe can be readily polarized using light from a Circular polarization laser. Typically the alkali metal rubidium is used for this purpose. The polarization can approach 50% of all the xenon atoms, a condition called hyperpolarization (physics). (For most atoms, a Boltzmann distribution of polarized atoms is produced, resulting in detectable spins of only one in every 105 nuclei.) As xenon's electron shell is symmetric, there is only a minimal coupling between the polarized nucleus and external
magnetic fields, so the hyperpolarized state can be conveniently maintained for a period of several days.{{cite book| first=Gustav Konrad | last=von Schulthess
| coauthors=Smith, Hans-Jørgen; Pettersson, Holger; Allison, David John
| year=1998 | title=The Encyclopaedia of Medical Imaging
| pages=p. 194 | publisher=Taylor & Francis
| id=ISBN 1901865134 --> The
hyperpolarization (physics) process renders the xenon 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.{{cite news| last=Irion | first=Robert | date=[March 23, [
| title=Head Full of Xenon? | publisher=Science News
| url=http://sciencenow.sciencemag.org/cgi/content/full/1999/323/3
| accessdate=2007-10-08 -->
Other
In nuclear energy applications, xenon is used in bubble chambers,{{cite book| first=Peter Louis | last=Galison | year=1997
| title=Image and Logic: A Material Culture of Microphysics
| pages=p. 339 | publisher=University of Chicago Press
| id=ISBN 0226279170 --> probes, and in other areas where a high molecular weight and inert nature is desirable.
Liquid xenon is being used as a medium for detecting hypothetical WIMPs, or WIMPs. When a WIMP collides with a xenon nucleus, it should, theoretically, strip an electron and create a primary
Scintillation (physics). By using xenon, this burst of energy could then be readily distinguished from similar events caused by particles such as cosmic rays.{{cite web,
| url=http://www.nature.com/news/2002/020429/full/news020429-6.html
| title=Xenon outs WIMPs | publisher=Nature
| accessdate=2007-10-08 --> However, the XENON experiment at the [Gran Sasso National Laboratory in Italy has thus far failed to find any confirmed WIMPs. Even if no WIMPs are detected though, the experiment will serve to constrain the properties of dark matter and some physics models.{{cite web
| last=Schumann | first=Marc | date=
October 10, [
| url=http://xenon.physics.rice.edu/
| title=XENON announced new best limits on Dark Matter
| publisher=Rice University | accessdate=2007-10-08 --> The current detector at this facility is five times as sensitive as other instruments world-wide, and the sensitivity will be increased by an order of magnitude in 2008.{{cite news
| last=Boyd | first=Jade | date=
August 23, [
| 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 -->
Xenon is the preferred fuel for
Ion propulsion of spacecraft because of its high atomic weight, ease of ionization, the ability to store it as a liquid at near room temperature (but at high pressure) yet easily converts 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) or
caesium. Xenon was first used for satellite ion engines during the 1970s.{{cite web,
| 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 --> It was later employed as a propellant for Europe's [SMART-1 spacecraft{{cite news
| author=Saccoccia, G.; del Amo, J. G.; Estublier, D.
| date=August 31, [
| title=Ion engine gets SMART-1 to the Moon
| publisher=ESA
| url=http://www.esa.int/SPECIALS/SMART-1/SEMLZ36LARE_0.html
| accessdate=2007-10-01
--> and for the three ion propulsion engines on NASA's Dawn Spacecraft.{{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
-->
Chemically, the
perxenate compounds are used as oxidizing agents in analytical chemistry.
Xenon difluoride is used as an etchant for
silicon, particularly in the production of
microelectromechanical systems (MEMS).{{cite conference| author=Brazzle, J.D.; 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=pp. 737-740
| publisher=IEEE
| date = July 28-August 1, 1975
| location = Maastricht, Netherlands
| id = ISBN 9780780382657
--> The anticancer drug
Fluorouracil can be produced by reacting Xenon difluoride with Uracil.{{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 --> Xenon is also used in [X-ray crystallography. Applied at high pressure (about 600 psi) to a protein crystal, xenon atoms bind in predominantly [hydrophobic cavities, often creating a high quality, isomorphous, heavy-atom derivative, which can be used for solving the "[phase problem".{{cite web
| author=Staff
| date=December 21, [
| url=http://www.srs.ac.uk/px/facilities/xenon_notes_1.html
| title=Protein Crystallography: Xenon and Krypton Derivatives for Phasing
| publisher=PX
| accessdate=2007-10-01
-->
Precautions
Xenon gas can be safely kept in normal sealed glass containers at
standard temperature and pressure. Xenon is non-
toxic, but many of its compounds are toxic due to their strong oxidation properties.{{cite web| author=Finkel, A. J.; Katz, J. J.; Miller, C. E.
| date=
April 1, [
| 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
-->
At 169 m/s, the speed of sound in xenon gas is slower than that in air169.44 m/s in xenon (at 0° C and 107 KPa), compared to 344 m/s in air. See: (due to the slower average speed of the heavy xenon atoms compared to nitrogen and oxygen molecules), so xenon lowers the resonant frequencies of the [vocal tract when inhaled. This produces a characteristic lowered voice pitch, opposite the high-pitched voice caused by inhalation of [helium. Like helium, xenon does not satisfy the body's need for oxygen and is a simple [asphyxiant; 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, although it too is an asphyxiant.{{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 -->
It is possible to safely breathe heavy gases such as xenon or sulfur hexafluoride when they include a 20% mixture of oxygen. 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. 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.{{cite web
| author=Staff | date=
August 1, [
| 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 -->
See also
References
External links
- WebElements.com – Xenon
- Xenon as an anesthetic
- USGS Periodic Table - Xenon
{{Elementbox_triplepoint | k=161.405 | pa=81.6 k| comment=-->{{Elementbox_isotopes_decay | mn=125 | sym=Xe| na=[synthetic radioisotope | hl=16.9 [hour
| dm=[electron capture | de=1.652 | pn=125 | ps=[iodine -->
{{Elementbox_isotopes_decay | mn=127 | sym=Xe| na=[synthetic radioisotope | hl=36.345 [day
| dm=[electron capture | de=0.662 | pn=127 | ps=[iodine -->
{{Elementbox_isotopes_decay | mn=133 | sym=Xe| na=[synthetic radioisotope | hl=5.247 [day
| dm=[beta emission | de=0.427 | pn=133 | ps=[caesium -->
{{Elementbox_isotopes_decay | mn=135 | sym=Xe| na=[synthetic radioisotope | hl=9.14 [hour
| dm=[beta emission | de=1.16 | pn=135 | ps=[caesium-->
Xenon (
International Phonetic Alphabet: ) is a
chemical element that has the symbol
Xe and
atomic number 54. A colorless, heavy, odorless
noble gas, xenon occurs in the earth's atmosphere in trace amounts. Although generally unreactive, xenon can undergo a few chemical reactions such as the formation of
xenon hexafluoroplatinate, the first noble gas compound to be synthesized.{{cite web,
| url=http://periodic.lanl.gov/elements/54.html | title=Xenon
| publisher=Los Alamos National Laboratory, Chemical Division
| accessdate=2007-09-26
-->{{cite book| last=Rabinovich | first=Viktor Abramovich
| coauthors=Vasserman, A. A.; Nedostup, V. I.; Veksler, L. S.
| year=1988
| title=Thermophysical properties of neon, argon, krypton, and xenon
| edition=English-language edition
| publisher=Hemisphere Publishing Corp.
| location=Washington, DC | id=ISBN 0195218337
| url=http://adsabs.harvard.edu/abs/1988wdch...10.....R -->—National Standard Reference Data Service of the USSR. Volume 10.
Naturally occurring xenon is made of
Isotopes of xenon, but there are also over 40 unstable isotopes that undergo
radioactive decay. Xenon is produced during supernova explosions and from the radioactive decay of elements such as
iodine,
uranium and plutonium. The isotope ratios of xenon are an important tool for studying the early history of the
Solar System. Xenon-135 is produced as a result of
nuclear fission and acts as a
neutron absorber in
nuclear reactors.
Xenon has many uses such as in xenon lamps and as a general anesthetic. The first
excimer laser design used a xenon dimer molecule (Xe2) as its lasing medium, and the earliest
laser designs used
xenon flash lamps as pumps. Xenon is also being used to search for hypothetical WIMP and as the propellant for
ion thrusters in spacecraft.
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.{{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 --> Sir Ramsay suggested the name xenon for this gas from the Greek language word ''ξένον'' [xenon, neuter singular form of ''ξένος'' xenos, meaning foreign, strange, or host.{{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 | pages=p. 906
-->{{cite book| author=Staff | year=1991
| title=The Merriam-Webster New Book of Word Histories
| pages=p. 513 | publisher=Merriam-Webster, Inc.
| id=ISBN 0877796033 --> In 1902, Sir Ramsay estimated the proportion of xenon in the Earth's atmosphere as one part in 20 million.
During the 1930s, the engineer Harold Edgerton began exploring strobe light technology for high-speed photography. In 1934 he pushed the time resolution down to a millionth of a second by creating an electrical spark inside a gas tube filled with xenon gas. By this means he invented the
xenon flash lamp.
Albert R. Behnke Jr. began exploring the causes of 'drunkenness' of deep-sea divers in 1939. 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
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.
In 1960, the physicist
John Reynolds discovered that certain meteorites 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. As the half-life of 129I is16 million years, this demonstrated that the meteorites were formed during the early history of the
Solar System, as the 129I isotope was likely generated by one or more supernovae before the Solar System was formed.{{cite book| first=Donald D. | last=Clayton | year=1983
| title=Principles of Stellar Evolution and Nucleosynthesis
| pages=p. 75 | edition=2nd edition
| publisher=University of Chicago Press | id=ISBN 0226109534 -->
{{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 -->
Xenon and the other noble gases were for a long time considered to be completely chemically inert and not able to form chemical compounds. However, in 1962 at the University of British Columbia, the first xenon compound,
xenon hexafluoroplatinate, was synthesized by
Neil Bartlett.{{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, [ |publisher=Chemical & Engineering News-->
Occurrence
Xenon is a
trace gas in
Earth's atmosphere, occurring at 0.087±0.001 parts per million (μL/L).{{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 edition
| doi=10.1002/0471238961.0701190508230114.a01.pub2
| isbn=047148511X --> It is also found in gases emitted from some [mineral springs. Radioactive species of xenon, for example, 133Xe and 135Xe, are produced by [neutron irradiation of fissionable material within [nuclear reactors.
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.{{cite book| first=Frank G. | last=Kerry | year=2007
| title=Industrial Gas Handbook: Gas Separation and Purification
| pages=pp. 101–103 | publisher=CRC Press
| id=ISBN 0849390052 -->
{{cite web| url=http://www.c-f-c.com/specgas_products/xenon.htm
| title=Xenon - Xe | accessdate=2007-09-07
|date=August 10, [ | publisher=CFC StarTec LLC
--> Extraction of a liter of xenon from the atmosphere requires 220
watt-hoursof energy.{{cite web,
| url=http://www.expresshealthcaremgmt.com/20050515/criticare10.shtml
| title=Xenon: A modern anaesthetic
| publisher=Indian Express Newspapers Limited
| accessdate=2007-10-10 --> Worldwide production of xenon in 1998 was estimated at 5000–7000 m³.{{cite book
| last=Häussinger | first=Peter
| coauthors=Reinhard Glatthaar, Wilhelm Rhode,
Helmut Kick, Christian Benkmann, Josef Weber, Hans-Jörg Wunschel,Viktor Stenke, Edith Leicht, Hermann Stenger| chapter=Noble Gases
| title=Ullmann's Encyclopedia of Industrial Chemistry
| publisher=Wiley | year=2001 | edition=6th edition
| doi=10.1002/14356007.a17_485 | isbn=3527201653 --> Due to 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 [Euro/L for xenon, 1 €/L for krypton, and 0.20 €/L for neon.
Xenon is relatively rare in the
Sun's atmosphere, on
Earth, and in the asteroids and comets. The atmosphere of Mars shows a similar xenon abundance to that of Earth:0.08 parts per million.{{cite web,
| url=http://nssdc.gsfc.nasa.gov/planetary/factsheet/marsfact.html
| title=Mars Fact Sheet | publisher=NASA
| accessdate=2007-10-10 --> However, Mars shows a higher proportion of 129Xe 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.{{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 -->
By contrast, the planet
Jupiter has an unusually high abundance of xenon in its atmosphere; about 2.6 times as much as the Sun. This high abundance remains unexplained, but may have been caused by an early and rapid buildup of [planetesimals—small, subplanetary bodies—before the solar nebula began to heat up. (Otherwise, xenon would not have been trapped in the planetesimal ices.) Within the [Solar System, the [nucleon fraction for all isotopes of xenon is 1.56×10-8, or one part in 64 million of the total mass.{{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 --> The problem of the low terrestrial xenon may potentially be explained by [covalent bonding of xenon to oxygen within [quartz, hence reducing the outgassing of xenon into the atmosphere.
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 to create xenon.{{cite book| first=Donald D. | last=Clayton | year=1983
| title=Principles of Stellar Evolution and Nucleosynthesis
| publisher=University of Chicago Press
| id=ISBN 0226109534 --> Instead, many isotopes of xenon are formed during [supernova explosions.{{cite conference
| author=Heymann, D.; Dziczkaniec, M.
| title =Xenon from intermediate zones of supernovae
| booktitle =Proceedings 10th Lunar and Planetary Science Conference
| pages =pp. 1943-1959
| publisher = Pergamon Press, Inc.
| date = March 19-23, 1979
| location = Houston, Texas
| url = http://adsabs.harvard.edu/abs/1976IAUS...73...75P
| accessdate = 2007-10-02
-->
Characteristics
An atom of xenon is defined as having a nucleus with 54
protons. At
standard temperature and pressure, pure xenon gas has a density of 5.761 kg/m3, about 4.5 times the surface density of the Earth's atmosphere, 1.217 kg/m3.{{cite web,
| url=http://nssdc.gsfc.nasa.gov/planetary/factsheet/earthfact.html
| title=Earth Fact Sheet | publisher=NASA
| accessdate=2007-10-04 --> As a liquid, xenon has a density of 3.52 g/mL, about 3.5 times the density of water. The density of solid xenon, 2.7 g/cm3, is only slightly below the average density of [granite, 2.75 g/cm3.{{cite book
| first=Pradyot | last=Patnaik | year=2003
| title=Handbook of Inorganic Chemicals
| publisher=McGraw-Hill Professional | id=ISBN 0070494398 --> Using [pascal (unit)s of [pressure, xenon has been forced into a metallic phase.
Xenon is a member of the zero-valency (chemistry) elements that are called noble gas or
inert gases. It is inert to most common chemical reactions (such as combustion, for example) because the outer valence shell is completely filled with eight electrons. This produces a stable, minimum energy configuration in which the outer electrons are tightly bound.{{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 --> However, xenon can be [Oxidation by powerful oxidizing agents, and multiple compounds of this noble gas have been synthesized.
In a gas-filled tube, xenon emits a
blue glow when the gas is excited by electrical discharge. Xenon emits a band of emission lines that span the visual spectrum,{{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 -->
but the most intense lines occur in the region of blue light, which produces the coloration.{{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 -->
Isotopes
Naturally occurring xenon is made of nine stable isotope isotopes. (124Xe, 134Xe and 136Xe are predicted to undergo
double beta decay, but this has never been observed, so they are considered to be stable.){{cite web| last=Lüscher | first=Roland | year=2006
| url=http://www.shef.ac.uk/physics/bus2006/talks/luscher_roland.pdf
| title=Status of ßß-decay in Xenon
| publisher=University of Sheffield
| accessdate=2007-10-01 -->
Besides these stable forms, there are over 40 unstable isotopes that have been studied. 129Xe is produced by [beta decay of 129[iodine ([half-life: 16 million years); 131mXe, 133Xe, 133mXe, and 135Xe are some of the [nuclear fission products of both 235[uranium and 239[plutonium,{{cite web
| last=Caldwell | first=Eric | date=January 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 --> and therefore used as indicators of nuclear explosions.
The artificial isotope Xenon-135 is of considerable significance in the operation of
nuclear reactor. 135Xe has a huge
neutron cross section for thermal neutrons, 2.6×106 Barn (unit),{{cite book| first=Weston M. | last=Stacey | year=2007
| title=Nuclear Reactor Physics | pages=p. 213
| publisher=Wiley-VCH | id=ISBN 3527406794 --> so it acts as a [neutron absorber or "[nuclear 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).{{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 -->
Relatively high concentrations of radioactive xenon isotopes are also found emanating from nuclear reactors due to the release of this fission gas from cracked fuel rods{{cite book| first=Edwards A. | last=Laws | year=2000
| title=Aquatic Pollution: An Introductory Text
| pages=p. 505 | publisher=John Wiley and Sons
| id=ISBN 0471348759 --> or fissioning of uranium in cooling water.{{cite news
| author=Staff | date=April 9, [
| title=A Nuclear Nightmare | publisher=Time
| url=http://www.time.com/time/magazine/article/0,9171,920196-4,00.html
| accessdate=2007-10-09 --> The concentrations of these isotopes are still usually low compared to naturally occurring radioactive noble gases such as [radon-222.A typical boiling-water nuclear reactor releases about 13,000 [Curie of 133Xe per year.
In a typical indoor environment, radon concentration is about 200 pCi/L.
{{cite web
|author=Staff
| date=June 16, [
| url=http://www.ccohs.ca/oshanswers/phys_agents/radon.html
| title=Radon in Buildings
| publisher=Canadian Centre for Occupational Health & Safety
| accessdate=2007-10-13
-->Thus an equivalent level of radioactivity from radon-222 would occupy:
\begin{smallmatrix} \frac{1.3 \times 10^4 \text{Ci-->{2.0 \times 10^{-10} \text{Ci/L--> = 6.5 \times 10^{14} L \end{smallmatrix}
or only 650 km3. Compare, for example, to the surface area of the
Earth, 5×108 km2, while looking at the first kilometer thickness of the atmosphere.
Because xenon is a tracer for two parent isotopes, xenon isotope ratios in
meteorites are a powerful tool for studying the formation of the solar system. The iodine-xenon method of Radiometric dating gives the time elapsed between
nucleosynthesis and the condensation of a solid object from the solar nebula. Xenon isotopic ratios such as 129Xe/130Xe and 136Xe/130Xe are also a powerful tool for understanding terrestrial differentiation and early outgassing. Excess 129Xe found in [carbon dioxide well gases from [New Mexico was believed to be from the decay of [Mantle (geology)-derived gases soon after Earth's formation.
Compounds
The first chemical compound of xenon, xenon hexafluoroplatinate, was synthesized in 1962. Now, many compounds of xenon are known, including
xenon difluoride (XeF2),
xenon tetrafluoride (XeF4),
xenon hexafluoride (XeF6),
xenon tetroxide (XeO4), and sodium perxenate (Na4XeO6). A highly explosive compound
xenon trioxide (XeO3) has also been made. Most of the more than 80{{cite web| url=http://www.chemnetbase.com/periodic_table/elements/xenon.htm
| title=Xenon | publisher=CRC Press
| accessdate=2007-10-08 --> xenon compounds found to date contain electro-negative fluorine or oxygen. When other atoms are bound (such as [hydrogen or [carbon), they are often part of a molecule containing fluorine or oxygen.{{cite book
| author=Harding, Charlie J.; Janes, Rob | year=2002
| title=Elements of the P Block
| publisher=Royal Society of Chemistry
| id=ISBN 0854046909 --> Some compounds of xenon are [colored but most are colorless.
Recently, at the
University of Helsinki in
Finland, a group of scientists (M. Räsänen
et al.) prepared xenon dihydride (HXeH), xenon hydride-hydroxide (HXeOH), and hydroxenoacetylene (HXeCCH). They are stable up to 40
kelvin.See the paragraph starting ''Many recent findings'' in [Deuterium molecules, HXeOD and DXeOH, have also been produced.
As well as compounds where xenon forms a chemical bond, xenon can form
clathrates, such as
xenon hydrate (Xe·5.75 H2O), where xenon atoms occupy vacancies in a lattice of water molecules.A molecular theory of general anesthesia, Linus Pauling,
Science 134, #3471 (July 7, 1961), pp. 15–21. Reprinted as pp. 1328–1334,
Linus Pauling: Selected Scientific Papers, vol. 2, edited by Barclay Kamb et al. River Edge, New Jersey: World Scientific: 2001, ISBN 9810229402. The
deuterated version of this hydrate has also been produced. Clathrate formation can be used to fractionally distill xenon, argon and krypton.
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 129Xe nuclear magnetic resonance 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.
Applications
Although xenon is rare and relatively expensive to extract from the Earth' atmosphere, it still has a number of useful commercial applications.
Illumination and optics
.Xenon is used in light-emitting devices called xenon flash lamps, which are used in
photographic flashes and stroboscopic lamps;{{cite book| first=James | last=Burke | year=2003
| title=Twin Tracks: The Unexpected Origins of the Modern World
| publisher=Oxford University Press
| id=ISBN 0743226194 --> to excite the [active laser medium in [lasers which then generate [coherent light;{{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 --> to produce laser power for [inertial confinement fusion and rarely in [bactericidal lamps.
Continuous, short-arc, high pressure
xenon arc lamps have a color temperature closely approximating noon sunlight and are used in solar simulators. After they were first introduced during the 1940s, these lamps began replacing the shorter-lived carbon arc lamps in movie projectors.{{cite book| first=David | last=Mellor | year=2000 | pages=p. 186
| title=Sound Person's Guide to Video
| publisher=Focal Press | id=ISBN 0240515951 --> They are employed in typical [35mm and [IMAX film projection systems, automotive [High-intensity discharge lamp 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 using electrodes. The interaction of this plasma with the electrodes generates ultraviolet photons, which then excite the
phosphor coating on the front of the display.{{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 -->{{cite news
| last=Marin | first=Rick | date=
March 21, [
| title=Plasma TV: That New Object Of Desire
| publisher=The New York Times -->
The first solid-state
laser, invented in 1960, was pumped by a xenon flashlamp.{{cite book| author=Toyserkani, E.; Khajepour, A.; Corbin, S.
| year=2004 | title=Laser Cladding
| publisher=CRC Press | id=ISBN 0849321727 -->
Bell laboratories later developed the high-gain helium-xenon (HeXe) gas laser.{{cite book| first=Joan Lisa | last=Bromberg
| year=1991 | title=The laser in America, 1950-1970
| publisher=MIT Press
| location=Cambridge, Mass.
| id=ISBN 0262023180 --> A year afterward, the xenon laser was developed; it was among the first gas lasers discovered. This laser has a very high gain, but is only capable of producing low power levels with saturation at several microwatts.{{cite conference
| first = L. W. | last = Casperson
| title = Gas Laser Instabilities and their Interpretation
| booktitle = Proceedings of a NATO Advanced Study Institute on Instabilities and Chaos in Quantum Optics
| publisher = Springer | date = June 28-July 7, 1987
| location = Ciocco, Italy | id = ISBN 0306429144 --> The first [excimer laser used a xenon [dimer (Xe2) energized by a beam of electrons to produce stimulated emission at an [ultraviolet wavelength of 172 [nanometre.
Xenon chloride and xenon fluoride have also been used in excimer (or, more accurately, exciplex) lasers.{{cite web| url=http://www.rstp.uwaterloo.ca/laser/documents/laser_types.html
| title=Laser Output | publisher=University of Waterloo
| accessdate=2007-10-07 --> The xenon chloride excimer laser has been employed, for example, in certain dermatological uses.
Anesthesia
Xenon has been used as a
general anesthetic, although it is expensive. As of 2005, the cost of 99.99% pure xenon gas is
United States dollar10 per liter. Even so, anesthesia machines that can deliver xenon are about to appear on the European market. Two mechanisms for xenon anesthesia have been proposed. The first one involves the inhibition of the [Plasma membrane Ca2+ ATPase—the mechanism cells use to remove calcium (Ca2+)—in the [cell membrane of [Chemical synapse. This results from a [conformational isomerism when xenon binds to nonpolar sites inside the protein. The second mechanism focuses on the non-specific interactions between the anesthetic and the [Lipid bilayer.
Xenon has a minimum alveolar concentration (MAC) of 0.63, making it 50% more potent than N2O as an anesthetic. Thus it can be used in concentrations with oxygen that have a lower risk of hypoxia. Unlike
nitrous oxide (N2O), xenon is not a greenhouse gas and so it is also viewed as environmentally friendly. Because of the high cost of xenon, however, economic application will require a closed system so that the gas can be recycled.
Medical imaging
gamma ray emission from the
radioisotope 133Xe of xenon can be used to image the heart, lungs, and brain, for example, by means of single photon emission computed tomography. 133Xe has also been used to measure blood flow.{{cite book| first=Ernst | last=Van Der Wall | year=1992
| title=What's New in Cardiac Imaging?: SPECT, PET, and MRI
| publisher=Springer | id=ISBN 0792316150 -->http://student.bmj.com/issues/04/01/education/8.php Introduction to imaging: The chest, John Frank, ''studentBMJ'' '''12''' (February 2004), pp. 1–44. Accessed on line October 19, [.http://brighamrad.harvard.edu/education/online/BrainSPECT/Theory/Xenon133.html Brain SPECT: Xenon-133. Accessed on line October 19, [.
When it is placed in the presence of an
alkali vapor, the nucleus of the Spin (physics) isotope 129Xe can be readily polarized using light from a
Circular polarization laser. Typically the alkali metal
rubidium is used for this purpose. The polarization can approach 50% of all the xenon atoms, a condition called hyperpolarization (physics). (For most atoms, a Boltzmann distribution of polarized atoms is produced, resulting in detectable spins of only one in every 105 nuclei.) As xenon's electron shell is symmetric, there is only a minimal coupling between the polarized nucleus and external magnetic fields, so the hyperpolarized state can be conveniently maintained for a period of several days.{{cite book| first=Gustav Konrad | last=von Schulthess
| coauthors=Smith, Hans-Jørgen; Pettersson, Holger; Allison, David John
| year=1998 | title=The Encyclopaedia of Medical Imaging
| pages=p. 194 | publisher=Taylor & Francis
| id=ISBN 1901865134 --> The
hyperpolarization (physics) process renders the xenon 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.{{cite news| last=Irion | first=Robert | date=[March 23, [
| title=Head Full of Xenon? | publisher=Science News
| url=http://sciencenow.sciencemag.org/cgi/content/full/1999/323/3
| accessdate=2007-10-08 -->
Other
In nuclear energy applications, xenon is used in bubble chambers,{{cite book| first=Peter Louis | last=Galison | year=1997
| title=Image and Logic: A Material Culture of Microphysics
| pages=p. 339 | publisher=University of Chicago Press
| id=ISBN 0226279170 --> probes, and in other areas where a high molecular weight and inert nature is desirable.
Liquid xenon is being used as a medium for detecting hypothetical
WIMPs, or WIMPs. When a WIMP collides with a xenon nucleus, it should, theoretically, strip an electron and create a primary
Scintillation (physics). By using xenon, this burst of energy could then be readily distinguished from similar events caused by particles such as
cosmic rays.{{cite web,
| url=http://www.nature.com/news/2002/020429/full/news020429-6.html
| title=Xenon outs WIMPs | publisher=Nature
| accessdate=2007-10-08 --> However, the XENON experiment at the [Gran Sasso National Laboratory in Italy has thus far failed to find any confirmed WIMPs. Even if no WIMPs are detected though, the experiment will serve to constrain the properties of dark matter and some physics models.{{cite web
| last=Schumann | first=Marc | date=
October 10, [
| url=http://xenon.physics.rice.edu/
| title=XENON announced new best limits on Dark Matter
| publisher=Rice University | accessdate=2007-10-08 --> The current detector at this facility is five times as sensitive as other instruments world-wide, and the sensitivity will be increased by an order of magnitude in 2008.{{cite news
| last=Boyd | first=Jade | date=August 23, [
| 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 -->
Xenon is the preferred fuel for
Ion propulsion of spacecraft because of its high atomic weight, ease of ionization, the ability to store it as a liquid at near room temperature (but at high pressure) yet easily converts 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) or caesium. Xenon was first used for satellite ion engines during the 1970s.{{cite web,
| 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 --> It was later employed as a propellant for Europe's [SMART-1 spacecraft{{cite news
| author=Saccoccia, G.; del Amo, J. G.; Estublier, D.
| date=
August 31, [
| title=Ion engine gets SMART-1 to the Moon
| publisher=ESA
| url=http://www.esa.int/SPECIALS/SMART-1/SEMLZ36LARE_0.html
| accessdate=2007-10-01
--> and for the three ion propulsion engines on NASA's Dawn Spacecraft.{{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
-->
Chemically, the
perxenate compounds are used as
oxidizing agents in
analytical chemistry. Xenon difluoride is used as an etchant for
silicon, particularly in the production of microelectromechanical systems (MEMS).{{cite conference| author=Brazzle, J.D.; 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=pp. 737-740
| publisher=IEEE
| date = July 28-August 1, 1975
| location = Maastricht, Netherlands
| id = ISBN 9780780382657
--> The anticancer drug
Fluorouracil can be produced by reacting Xenon difluoride with Uracil.{{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 --> Xenon is also used in [X-ray crystallography. Applied at high pressure (about 600 psi) to a protein crystal, xenon atoms bind in predominantly [hydrophobic cavities, often creating a high quality, isomorphous, heavy-atom derivative, which can be used for solving the "[phase problem".{{cite web
| author=Staff
| date=December 21, [
| url=http://www.srs.ac.uk/px/facilities/xenon_notes_1.html
| title=Protein Crystallography: Xenon and Krypton Derivatives for Phasing
| publisher=PX
| accessdate=2007-10-01
-->
Precautions
Xenon gas can be safely kept in normal sealed glass containers at standard temperature and pressure. Xenon is non-toxic, but many of its compounds are toxic due to their strong oxidation properties.{{cite web| author=Finkel, A. J.; Katz, J. J.; Miller, C. E.
| date=
April 1, [
| 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
-->
At 169 m/s, the speed of sound in xenon gas is slower than that in air169.44 m/s in xenon (at 0° C and 107 KPa), compared to 344 m/s in air. See: (due to the slower average speed of the heavy xenon atoms compared to nitrogen and oxygen molecules), so xenon lowers the resonant frequencies of the [vocal tract when inhaled. This produces a characteristic lowered voice pitch, opposite the high-pitched voice caused by inhalation of [helium. Like helium, xenon does not satisfy the body's need for oxygen and is a simple [asphyxiant; 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, although it too is an asphyxiant.{{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 -->
It is possible to safely breathe heavy gases such as xenon or sulfur hexafluoride when they include a 20% mixture of oxygen. 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. 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.{{cite web
| author=Staff | date=
August 1, [
| 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 -->
See also
References
External links
- WebElements.com – Xenon
- Xenon as an anesthetic
- USGS Periodic Table - Xenon
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