In many applications, the noble gases are used to provide an inert atmosphere. Argon is used in the synthesis of [[air sensitive|air-sensitive compounds]] that are sensitive to nitrogen. Solid argon is also used for the study of very unstable compounds, such as [[reactive intermediate]]s, by trapping them in an inert [[matrix isolation|matrix]] at very low temperatures.<ref>{{cite journal |journal=Chem. Soc. Rev. |year=1980 |volume=9 |pages=1–23 |doi=10.1039/CS9800900001 |title=The matrix isolation technique and its application to organic chemistry |author=Dunkin, I. R.}}</ref> Helium is used as the carrier medium in [[gas chromatography]], as a filler gas for [[thermometers]], and in devices for measuring radiation, such as the [[Geiger counter]] and the [[bubble chamber]].<ref name=kirk/> Helium and argon are both commonly used to shield [[welding arc]]s and the surrounding [[base metal]] from the atmosphere during welding and cutting, as well as in other metallurgical processes and in the production of silicon for the semiconductor industry.<ref name="ullmann" / > Helium is also used as filling gas in nuclear fuel rods for nuclear reactors.<ref>{{cite journal|last1=Horhoianu|first1=G.|title=Thermal behaviour of CANDU type fuel rods during steady state and transient operating conditions|journal=Annals of Nuclear Energy|volume=26|pages=1437–1445|year=1999|doi=10.1016/S0306-4549(99)00022-5|issue=16|last2=Ionescu|first2=D. V.|last3=Olteanu|first3=G.}}</ref> ▼[[File:Goodyear-blimp.jpg|thumb|right|Goodyear Blimp|alt=Cigar-shaped blimp with "Good Year" written on its side.]]
Since the [[Hindenburg disaster|''Hindenburg'' disaster]] in 1937,<ref>{{cite news|title=Disaster Ascribed to Gas by Experts|work=[[The New York Times]]|date=1937-05-07|page=1}}</ref> helium has replaced hydrogen as a [[lifting gas]] in [[blimp]]s and [[balloon]]s due to its lightness and incombustibility, despite an 8.6%<ref>{{cite web
|last=Freudenrich|first=Craig|year=2008
|url=http://science.howstuffworks.com/blimp2.htm
|title=How Blimps Work|publisher=HowStuffWorks
|accessdate=2008-07-03}}</ref> decrease in buoyancy.<ref name="brit"/>
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▲In many applications, the noble gases are used to provide an inert atmosphere. Argon is used in the synthesis of [[air sensitive|air-sensitive compounds]] that are sensitive to nitrogen. Solid argon is also used for the study of very unstable compounds, such as [[reactive intermediate]]s, by trapping them in an inert [[matrix isolation|matrix]] at very low temperatures.<ref>{{cite journal |journal=Chem. Soc. Rev. |year=1980 |volume=9 |pages=1–23 |doi=10.1039/CS9800900001 |title=The matrix isolation technique and its application to organic chemistry |author=Dunkin, I. R.}}</ref> Helium is used as the carrier medium in [[gas chromatography]], as a filler gas for [[thermometers]], and in devices for measuring radiation, such as the [[Geiger counter]] and the [[bubble chamber]].<ref name=kirk/> Helium and argon are both commonly used to shield [[welding arc]]s and the surrounding [[base metal]] from the atmosphere during welding and cutting, as well as in other metallurgical processes and in the production of silicon for the semiconductor industry.<ref name="ullmann" />
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Some noble gases have direct application in medicine. Helium is sometimes used to improve the ease of breathing of [[asthma]] sufferers.<ref name=ullmann/> Xenon is used as an [[anesthetic]] because of its high solubility in lipids, which makes it more potent than the usual [[nitrous oxide]], and because it is readily eliminated from the body, resulting in faster recovery.<ref>{{cite journal|author1=Sanders, Robert D. |author2=Ma, Daqing |author3=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> Xenon finds application in medical imaging of the lungs through hyperpolarized MRI.<ref>{{cite journal|last=Albert|first=M. S.|last2=Balamore|first2=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|pmid=11543065|issue=2–3|bibcode= 1998NIMPA.402..441A }}</ref> Radon, which is highly radioactive and is only available in minute amounts, is used in [[radiotherapy]].<ref name=brit />
[[Dosya:Modern 3T MRI.JPG|thumb|left|Sıvı helyum, modern [[manyetik rezonans görüntüleme]] tarayıcılarında, süperiletken mıknatısların soğutulması için kullanılır.]]
Soy gazlar, diğer elementlere göre sahip oldukları düşük erime ve kaynama noktaları nedeniyle [[kriyojenik]] [[soğutucu]] olarak kullanılmaktadırlar.{{fact}} Özellikle kaynama noktası {{convert|4.2|K}} olan [[sıvı helyum]], [[nükleer manyetik rezonans görüntüleme]] ve [[nükleer manyetik rezonans]]ta ihtiyaç duyulan [[süper iletkenli mıknatıs]]lar için kullanılır.<ref>{{Dergi kaynağı |başlık=Demountable coaxial gas-cooled current leads for MRI superconducting magnets |son1=Zhang |ilk1=C. J. |son2=Zhou |ilk2=X. T. |son3=Yang |ilk3=L. |dergi=Magnetics, IEEE Transactions on |yayımcı=[[IEEE]] |cilt=28 |sayı=1 |yıl=1992 |sayfalar=957-959 |dil=İngilizce |doi=10.1109/20.120038 |bibcode=1992ITM....28..957Z}}</ref> Sıvı helyum kadar düşük sıcaklıklara ulaşamamasına karşın sıvı neon; sıvı helyumdan 400, sıvı hidrojenden ise 3 kattan daha fazla soğutma kapasitesine sahip olduğundan kriyojenikte kullanılmaktadır.<ref name=ullmann/>
Helium is used as a component of [[breathing gases]] to replace nitrogen, due its low [[solubility]] in fluids, especially in [[lipids]]. Gases are absorbed by the [[blood]] and [[body tissue]]s when under pressure like in [[scuba diving]], which causes an [[anesthetic]] effect known as [[nitrogen narcosis]].<ref name=Fowler>{{cite journal |last=Fowler |first=B. |last2=Ackles|first2=K. N.|last3=Porlier|first3=G. |title=Effects of inert gas narcosis on behavior—a critical review |journal=Undersea Biomed. Res. |volume=12 |issue=4 |pages=369–402 |year=1985 |issn=0093-5387 |oclc=2068005 |pmid=4082343 |url=http://archive.rubicon-foundation.org/3019 |accessdate=2008-04-08}}</ref> Due to its reduced solubility, little helium is taken into [[cell membranes]], and when helium is used to replace part of the breathing mixtures, such as in [[Trimix (breathing gas)|trimix]] or [[heliox]], a decrease in the narcotic effect of the gas at depth is obtained.<ref>{{harvnb|Bennett|1998|p=176}}</ref> Helium's reduced solubility offers further advantages for the condition known as [[Decompression sickness#Mechanism|decompression sickness]], or ''the bends''.<ref name="brit"/><ref>{{cite journal |last=Vann|first=R. D. (ed)|title=The Physiological Basis of Decompression|journal=38th Undersea and Hyperbaric Medical Society Workshop |volume=75(Phys)6-1-89 |year=1989 |pages=437 |url=http://archive.rubicon-foundation.org/6853 |accessdate=2008-05-31}}</ref> The reduced amount of dissolved gas in the body means that fewer gas bubbles form during the decrease in pressure of the ascent. Another noble gas, argon, is considered the best option for use as a [[drysuit]] inflation gas for scuba diving.<ref>{{cite web |last=Maiken |first=Eric |title=Why Argon? |url=http://www.decompression.org/maiken/Why_Argon.htm |accessdate=2008-06-26|publisher=Decompression|date=2004-08-01}}</ref> Helium is also used as filling gas in nuclear fuel rods for nuclear reactors.<ref>{{cite journal|last1=Horhoianu|first1=G.|title=Thermal behaviour of CANDU type fuel rods during steady state and transient operating conditions|journal=Annals of Nuclear Energy|volume=26|pages=1437–1445|year=1999|doi=10.1016/S0306-4549(99)00022-5|issue=16|last2=Ionescu|first2=D. V.|last3=Olteanu|first3=G.}}</ref>
Helyum, sıvılardaki özellikle de [[lipit]]lerdeki düşük çözünürlüğü sebebiyle [[solunum gazı]] bileşeni olarak azotun yerine kullanılır. Gazlar, [[aletli dalış]]ta olduğu gibi basınç altında [[kan]] ve [[doku (biyoloji)|doku]] tarafından absorbe edilir ve [[derinlik sarhoşluğu]] (azot narkozu) olarak bilinen [[anestezik]] etkiye sebep olur.<ref name=Fowler>{{Dergi kaynağı|last=Fowler |first=B |coauthors=Ackles, K. N.; Porlier, G. |title=Effects of inert gas narcosis on behavior—a critical review |journal=Undersea Biomed. Res. |volume=12 |issue=4 |pages=369–402 |year=1985 |issn=0093-5387 |oclc=2068005 |pmid=4082343 |url=http://archive.rubicon-foundation.org/3019 |accessdate=2008-04-08 }}</ref> Düşük çözünürlüğü nedeniyle az miktarda helyum hücre zarlarından içeri alınır ve helyum ''[[Trimix (solunum gazı)|trimix]]'' (helyum-oksijen-nitrojen) ve ''[[heliox]]''{{'}}ta (helyum-oksijen) olduğu gibi solunum gazı parçası olarak kullanılırsa gazın derindeki narkotik etkisinde düşme olur.<ref>{{harvnb|Bennett|1998|p=176}}</ref> Helyumun düşük çözünürlüğünun bunlardan başka bir getirisi de [[dekompresyon hastalığı]] olarak bilinen durumda ek avantajlar sağlamasıdır.<ref name="brit"/><ref name=38uhms>{{Dergi kaynağı|last=Vann|first=R. D. (ed)|title=The Physiological Basis of Decompression|journal=38th Undersea and Hyperbaric Medical Society Workshop |volume=75(Phys)6-1-89 |year=1989 |pages=437 |url=http://archive.rubicon-foundation.org/6853 |accessdate=2008-05-31 }}</ref> Vücutta çözünmüş gazın küçük miktarda bulunması, yükselme sırasında basınçtaki düşüşle birlikte daha az gazın kabarcık şekline dönüşmesi anlamına gelir. Diğer bir soy gaz argonun ise aletli dalış için [[kuru elbise]]de şişirme gazı olarak kullanımının en iyi seçenek olduğu kabul edilir.
<ref>{{Web kaynağı | url = http://www.decompression.org/maiken/Why_Argon.htm | başlık = Why Argon? | erişimtarihi = 2008-06-26 | yayımcı = Decompression | tarih = 2004-08-01 | ilk = Eric | son = Maiken | arşivurl = http://web.archive.org/web/20151206190126/http://www.decompression.org:80/maiken/Why_Argon.htm | arşivtarihi = 6 Aralık 2015}}</ref>
[[Dosya:Goodyear-blimp.jpg|thumb|right|İkonik Goodyear Zeplinlerinden ''The Spirit of Goodyear'']]
1937'deki [[Hindenburg faciası|''Hindenburg'' faciasından]] sonra,<ref>{{Haber kaynağı|başlık=Disaster Ascribed to Gas by Experts|iş=[[The New York Times]]|tarih=1937-05-07|sayfa=1}}</ref> helyum, yüzme özelliğindeki %8.6<ref>{{Web kaynağı | url = http://science.howstuffworks.com/blimp2.htm | başlık = How Blimps Work | erişimtarihi = 2008-07-03 | yayımcı = HowStuffWorks | yıl = 2008 | ilk = Craig | son = Freudenrich | arşivurl = http://web.archive.org/web/20100429060014/http://science.howstuffworks.com:80/blimp2.htm | arşivtarihi = 29 Nisan 2010}}</ref> düşüşe rağmen<ref name="brit"/> hafifliği ve tutuşmazlığı sebebiyle [[zeplin]] ve [[Balon (hava taşıtı)|balonlarda]] kaldırma gazı olarak hidrojenin yerini aldı.
Birçok uygulamada soy gazlar inert atmosfer (nötr veya yansız atmosfer) sağlamak amacıyla kullanılır. Argon azota hassas olan [[havaya hassas bileşikler]]in sentezinde kullanılır. Katı argon ayrıca, [[reaksiyon ara ürünleri]] gibi çok kararsız bileşiklerin araştırılmasında da kullanılır. Bu araştırmalarda bileşikler çok düşük sıcaklıklarda bir inert [[Matris izolasyonu|matriste]] tuzaklanır.<ref>{{Dergi kaynağı|dergi=Chem. Soc. Rev. |yıl=1980 |cilt=9 |sayfalar=1–23 |doi=10.1039/CS9800900001 |başlık=The matrix isolation technique and its application to organic chemistry |yazar=Dunkin, I. R. }}</ref> Helyum [[gaz kromatografisi]]nde taşıyıcı ortam olarak, termometrelerde gaz dolgusu olarak ve kabarcık odası ve [[Geiger sayacı]] gibi radyasyon ölçmeye yarayan aletlerde kullanılır.<ref name=kirk/> Helyum ve argon genellikle [[ark kaynağı|ark kaynaklarında]] koruma oluşturması için kullanılır ve kaynak ve kesme esnasında ana metalin etrafını sarar. Ayrıca diğer metalurjik süreçlerde ve yarı iletken endüstrisindeki silisyum ve germanyum üretiminde koruyucu soy gaz olarak kullanılır.<ref name="ullmann" />
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