View source for Isotopes of oxygen

{{Short description|Type of isotope that has 8 protons}}
{{Infobox oxygen isotopes}}

There are three known stable [[isotope]]s of [[oxygen]] (<sub>8</sub>O): [[Oxygen-16|{{SimpleNuclide|Oxygen|16}}]], [[Oxygen-17|{{SimpleNuclide|Oxygen|17}}]], and [[Oxygen-18|{{SimpleNuclide|Oxygen|18}}]].

[[Radioactive isotope|Radioactive isotopes]] ranging from {{SimpleNuclide|Oxygen|11}} to {{SimpleNuclide|Oxygen|28}} have also been characterized, all short-lived. The longest-lived radioisotope is {{SimpleNuclide|Oxygen|15}} with a [[half-life]] of {{val|122.266|(43)|ul=seconds}}, while the shortest-lived isotope is {{SimpleNuclide|Oxygen|11}} with a half-life of {{val|198|(12)|ul=yoctoseconds}} (though the half-lives of the [[proton drip line|neutron-unbound]] {{SimpleNuclide|Oxygen|27}} and {{SimpleNuclide|Oxygen|28}} are still unknown).

==List of isotopes==
{{Isotopes table
|symbol=O
|refs=NUBASE2020, AME2020 II<!-- was updated as of 2021-12-26) -->
|notes=m, resonance, unc(), spin(), spin{{sup|#}}, daughter-st, p, n
}}
|-
| {{SimpleNuclide|Oxygen|11}}<ref name="Oxygen-11">{{cite journal |last1=Webb |first1=T. B. |display-authors=et al. |title=First Observation of Unbound <sup>11</sup>O, the Mirror of the Halo Nucleus <sup>11</sup>Li |journal=Physical Review Letters |date=2019 |volume=122 |issue=12 |pages=122501–1–122501–7 |doi=10.1103/PhysRevLett.122.122501 |pmid=30978039 |arxiv=1812.08880|bibcode=2019PhRvL.122l2501W |s2cid=84841752 }}</ref>
| style="text-align:right" | 8
| style="text-align:right" | 3
| {{val|11.051250|(60)}}
| {{val|198|(12)|u=ys}}<br/>[{{val|2.31|(14)|ul=MeV}}]
| [[proton emission|2p]]
| {{SimpleNuclide|Carbon|9}}
| (3/2−)
|
|
|-
| {{SimpleNuclide|Oxygen|12}}
| style="text-align:right" | 8
| style="text-align:right" | 4
| {{val|12.034368|(13)}}
| {{val|8.9|(3.3)|u=zs}}
| 2p
| {{SimpleNuclide|Carbon|10}}
| 0+
| 
| 
|-
| rowspan=2|{{SimpleNuclide|Oxygen|13}}
| rowspan=2 style="text-align:right" | 8
| rowspan=2 style="text-align:right" | 5
| rowspan=2|{{val|13.024815|(10)}}
| rowspan=2|{{val|8.58|(5)|u=ms}}
| β<sup>+</sup> ({{val|89.1|(2)|u=%}})
| {{SimpleNuclide|Nitrogen|13}}
| rowspan=2|(3/2−)
| rowspan=2|
| rowspan=2|
|-
| β<sup>+</sup>p ({{val|10.9|(2)|u=%}})
| '''{{SimpleNuclide|Carbon|12}}'''
|-
| {{SimpleNuclide|Oxygen|14}}
| style="text-align:right" | 8
| style="text-align:right" | 6
| {{val|14.008596706|(27)}}
| {{val|70.621|(11)|u=s}}
| β<sup>+</sup>
| '''{{SimpleNuclide|Nitrogen|14}}'''
| 0+
|
|
|-
| {{SimpleNuclide|Oxygen|15}}
| style="text-align:right" | 8
| style="text-align:right" | 7
| {{val|15.0030656|(5)}}
| {{val|122.266|(43)|u=s}}
| β<sup>+</sup>
| '''{{SimpleNuclide|Nitrogen|15}}'''
| 1/2−
|
|
|-
| [[Oxygen-16|{{SimpleNuclide|Oxygen|16}}]]<ref group="n" name="d18">The ratio between {{SimpleNuclide|Oxygen|16}} and {{SimpleNuclide|Oxygen|18}} is used to [[δ18O|deduce ancient temperatures]].</ref>
| style="text-align:right" | 8
| style="text-align:right" | 8
| {{val|15.994914619257|(319)}}
| colspan="3" style="text-align:center;"|'''Stable'''
| 0+
| colspan="2" style="text-align:center;"|[{{val|0.99738}}, {{val|0.99776}}]<ref name="Atomic Weight of Oxygen">{{Cite web |title=Atomic Weight of Oxygen {{!}} Commission on Isotopic Abundances and Atomic Weights |url=https://ciaaw.org/oxygen.htm |access-date=2022-03-15 |website=ciaaw.org}}</ref>
|-
| [[Oxygen-17|{{SimpleNuclide|Oxygen|17}}]]<ref group="n">Can be used in NMR studies of metabolic pathways.</ref>
| style="text-align:right" | 8
| style="text-align:right" | 9
| {{val|16.999131755953|(692)}}
| colspan="3" style="text-align:center;"|'''Stable'''
| 5/2+
| colspan="2" style="text-align:center;"|[{{val|0.000367}}, {{val|0.000400}}]<ref name="Atomic Weight of Oxygen" />
|-
| [[Oxygen-18|{{SimpleNuclide|Oxygen|18}}]]<ref group="n" name="d18" /><ref group="n">Can be used in studying certain metabolic pathways.</ref>
| style="text-align:right" | 8
| style="text-align:right" | 10
| {{val|17.999159612136|(690)}}
| colspan="3" style="text-align:center;"|'''Stable'''
| 0+
| colspan="2" style="text-align:center;"|[{{val|0.00187}}, {{val|0.00222}}]<ref name="Atomic Weight of Oxygen" />
|-
| {{SimpleNuclide|Oxygen|19}}
| style="text-align:right" | 8
| style="text-align:right" | 11
| {{val|19.0035780|(28)}}
| {{val|26.470|(6)|u=s}}
| β<sup>−</sup>
| '''{{SimpleNuclide|Fluorine|19}}'''
| 5/2+
|
|
|-
| {{SimpleNuclide|Oxygen|20}}
| style="text-align:right" | 8
| style="text-align:right" | 12
| {{val|20.0040754|(9)}}
| {{val|13.51|(5)|u=s}}
| β<sup>−</sup>
| {{SimpleNuclide|Fluorine|20}}
| 0+
|
|
|-
| rowspan=2|{{SimpleNuclide|Oxygen|21}}
| rowspan=2 style="text-align:right" | 8
| rowspan=2 style="text-align:right" | 13
| rowspan=2|{{val|21.008655|(13)}}
| rowspan=2|{{val|3.42|(10)|u=s}}
| β<sup>−</sup>
| {{SimpleNuclide|Fluorine|21}}
| rowspan=2|(5/2+)
| rowspan=2|
| rowspan=2|
|-
| β<sup>−</sup>n ?<ref group="n" name="decay mode 1">Decay mode shown is energetically allowed, but has not been experimentally observed to occur in this nuclide.</ref>
| {{SimpleNuclide|Fluorine|20}} ?
|-
| rowspan=2|{{SimpleNuclide|Oxygen|22}}
| rowspan=2 style="text-align:right" | 8
| rowspan=2 style="text-align:right" | 14
| rowspan=2|{{val|22.009970|(60)}}
| rowspan=2|{{val|2.25|(9)|u=s}}
| β<sup>−</sup> (> {{val|78|u=%}})
| {{SimpleNuclide|Fluorine|22}}
| rowspan=2|0+
| rowspan=2|
| rowspan=2|
|-
| β<sup>−</sup>n (< {{val|22|u=%}})
| {{SimpleNuclide|Fluorine|21}}
|-
| rowspan=2|{{SimpleNuclide|Oxygen|23}}
| rowspan=2 style="text-align:right" | 8
| rowspan=2 style="text-align:right" | 15
| rowspan=2|{{val|23.015700|(130)}}
| rowspan=2|{{val|97|(8)|u=ms}}
| β<sup>−</sup> ({{val|93|(2)|u=%}})
| {{SimpleNuclide|Fluorine|23}}
| rowspan=2|1/2+
| rowspan=2|
| rowspan=2|
|-
| β<sup>−</sup>n ({{val|7|(2)|u=%}})
| {{SimpleNuclide|Fluorine|22}}
|-
| rowspan=2|{{SimpleNuclide|Oxygen|24}}
| rowspan=2 style="text-align:right" | 8
| rowspan=2 style="text-align:right" | 16
| rowspan=2|{{val|24.019860|(180)}}
| rowspan=2|{{val|77.4|(4.5)|u=ms}}
| β<sup>−</sup> ({{val|57|(4)|u=%}})
| {{SimpleNuclide|Fluorine|24}}
| rowspan=2|0+
| rowspan=2|
| rowspan=2|
|-
| β<sup>−</sup>n ({{val|43|(4)|u=%}})
| {{SimpleNuclide|Fluorine|23}}
|-
| {{SimpleNuclide|Oxygen|25}}
| style="text-align:right" | 8
| style="text-align:right" | 17
| {{val|25.029340|(180)}}
| {{val|5.18|(35)|u=zs}}
| n
| {{SimpleNuclide|Oxygen|24}}
| 3/2+{{sup|#}}
|
|
|-
| {{SimpleNuclide|Oxygen|26}}
| style="text-align:right" | 8
| style="text-align:right" | 18
| {{val|26.037210|(180)}}
| {{val|4.2|(3.3)|u=ps}}
| 2n
| {{SimpleNuclide|Oxygen|24}}
| 0+
|
|
|-
| rowspan=2|{{SimpleNuclide|Oxygen|27}}
| rowspan=2 style="text-align:right" | 8
| rowspan=2 style="text-align:right" | 19
| rowspan=2|{{val|27.047960|(540)}}{{sup|#}}
| rowspan=2|< {{val|260|u=ns}}
| n ?<ref group="n" name="decay mode 1">Decay mode shown is energetically allowed, but has not been experimentally observed to occur in this nuclide.</ref>
| {{SimpleNuclide|Oxygen|26}} ?
| rowspan=2|3/2+{{sup|#}}
| rowspan=2|
| rowspan=2|
|-
| 2n ?<ref group="n" name="decay mode 1">Decay mode shown is energetically allowed, but has not been experimentally observed to occur in this nuclide.</ref>
| {{SimpleNuclide|Oxygen|25}} ?
|-
| rowspan=2|{{SimpleNuclide|Oxygen|28}}
| rowspan=2 style="text-align:right" | 8
| rowspan=2 style="text-align:right" | 20
| rowspan=2|{{val|28.055910|(750)}}{{sup|#}}
| rowspan=2|< {{val|100|u=ns}}
| 2n ?<ref group="n" name="decay mode 1">Decay mode shown is energetically allowed, but has not been experimentally observed to occur in this nuclide.</ref>
| {{SimpleNuclide|Oxygen|26}} ?
| rowspan=2|0+
| rowspan=2|
| rowspan=2|
|-
| β<sup>−</sup> ({{val|0|u=%}})
| {{SimpleNuclide|Fluorine|28}}
{{Isotopes table/footer}}

== Stable isotopes ==
[[File:Evolved star fusion shells.svg|250px|thumb|Late in a massive star's life, {{SimpleNuclide|Oxygen|16}} concentrates in the N-shell, {{SimpleNuclide|Oxygen|17}} in the H-shell and {{SimpleNuclide|Oxygen|18}} in the He-shell.]]
Natural oxygen is made of three stable [[isotope]]s, [[Oxygen-16|{{SimpleNuclide|Oxygen|16}}]], [[Oxygen-17|{{SimpleNuclide|Oxygen|17}}]], and [[Oxygen-18|{{SimpleNuclide|Oxygen|18}}]], with {{SimpleNuclide|Oxygen|16}} being the most abundant (99.762% [[natural abundance]]). Depending on the terrestrial source, the standard atomic weight varies within the range of [{{val|15.99903}}, {{val|15.99977}}] (the [[conventional atomic weight|conventional value]] is 15.999).

{{SimpleNuclide|Oxygen|16}} has high relative and absolute abundance because it is a principal product of [[stellar evolution]] and because it is a primary isotope, meaning it can be made by [[star]]s that were initially [[hydrogen]] only.<ref name="Meyer2005">{{cite conference
 | author=B. S. Meyer
 | title = Nucleosynthesis and galactic chemical evolution of the isotopes of oxygen
 | conference = Workgroup on Oxygen in the Earliest Solar System
 | date = September 19–21, 2005
 | location = Gatlinburg, Tennessee
 | url= http://www.lpi.usra.edu/meetings/ess2005/pdf/9022.pdf
 | book-title = Proceedings of the NASA Cosmochemistry Program and the Lunar and Planetary Institute
 | conference-url = http://www.lpi.usra.edu/meetings/ess2005/
 | id = 9022
}}</ref> Most {{SimpleNuclide|Oxygen|16}} is [[nucleosynthesis|synthesized]] at the end of the [[helium fusion]] process in [[star]]s; the [[triple-alpha process]] creates [[Carbon-12|{{SimpleNuclide|Carbon|12}}]], which captures an additional [[Helium-4|{{SimpleNuclide|Helium|4}}]] nucleus to produce {{SimpleNuclide|Oxygen|16}}. The [[neon burning process]] creates additional {{SimpleNuclide|Oxygen|16}}.<ref name="Meyer2005" />

Both {{SimpleNuclide|Oxygen|17}} and {{SimpleNuclide|Oxygen|18}} are secondary isotopes, meaning their synthesis requires seed nuclei. {{SimpleNuclide|Oxygen|17}} is primarily made by burning hydrogen into helium in the [[CNO cycle]], making it a common isotope in the hydrogen burning zones of stars.<ref name="Meyer2005" /> Most {{SimpleNuclide|Oxygen|18}} is produced when [[Nitrogen|{{SimpleNuclide|Nitrogen|14}}]] (made abundant from CNO burning) captures a {{SimpleNuclide|Helium|4}} nucleus, becoming [[Fluorine-18|{{SimpleNuclide|Fluorine|18}}]]. This quickly (half life around 110 minutes) [[beta decay]]s to {{SimpleNuclide|Oxygen|18}} making that isotope common in the helium-rich zones of stars.<ref name="Meyer2005" /> About 10<sup>9</sup> [[kelvin]] is needed to [[nuclear fusion|fuse]] oxygen into [[sulfur]].{{sfn|Emsley|2001|p=297}}

An atomic mass of 16 was assigned to oxygen prior to the definition of the unified [[atomic mass unit]] based on {{SimpleNuclide|Carbon|12}}.{{sfn|Parks|Mellor|1939|loc=Chapter VI, Section 7}} Since physicists referred to {{SimpleNuclide|Oxygen|16}} only, while chemists meant the natural mix of isotopes, this led to slightly different mass scales.

==Applications of various isotopes==
Measurements of [[Oxygen isotope ratio cycle|<sup>18</sup>O/<sup>16</sup>O ratio]] are often used to interpret changes in [[paleoclimate]]. Oxygen in Earth's air is {{val|99.759|u=%}} {{SimpleNuclide|Oxygen|16}}, {{val|0.037|u=%}} {{SimpleNuclide|Oxygen|17}} and {{val|0.204|u=%}} {{SimpleNuclide|Oxygen|18}}.{{sfn|Cook|Lauer|1968|p=500}} [[Water]] molecules with a lighter isotope are slightly more likely to [[evaporate]] and less likely to fall as [[Precipitation (meteorology)|precipitation]],<ref>{{cite journal |last=Dansgaard |first=W |year=1964 |title=Stable isotopes in precipitation |journal=Tellus |volume=16 |issue=4 |pages=436–468 
|url=http://www.ldeo.columbia.edu/~polissar/OrgGeochem/dansgaard-1964-stable-isoto.pdf |doi=10.1111/j.2153-3490.1964.tb00181.x|bibcode=1964Tell...16..436D }}</ref> so Earth's freshwater and polar ice have slightly less ({{val|0.1981|u=%}}) {{SimpleNuclide|Oxygen|18}} than air ({{val|0.204|u=%}}) or [[seawater]] ({{val|0.1995|u=%}}). This disparity allows analysis of temperature patterns via historic [[Oxygen-18#Paleoclimatology|ice cores]].

Solid samples (organic and inorganic) for oxygen isotopic ratios are usually stored in silver cups and measured with [[pyrolysis]] and [[mass spectrometry]].<ref name="Tsang2020">{{Cite journal|last1=Tsang|first1=Man-Yin|last2=Yao|first2=Weiqi|last3=Tse|first3=Kevin|date=2020|editor-last=Kim|editor-first=Il-Nam|title=Oxidized silver cups can skew oxygen isotope results of small samples|journal=Experimental Results|language=en|volume=1|pages=e12|doi=10.1017/exp.2020.15|issn=2516-712X|doi-access=free}}</ref> Researchers need to avoid improper or prolonged storage of the samples for accurate measurements.<ref name="Tsang2020" />

Due to natural oxygen being mostly {{chem|16|O}} samples enriched with the other stable isotopes can be used for [[isotope labeling]]. For example, it was proven, that the oxygen released in [[photosynthesis]] originates in {{chem|H<sub>2</sub>O}}, rather than in the also consumed {{CO2}}, by isotope tracing experiments. The oxygen contained in {{CO2}} in turn is used to make up the sugars formed by photosynthesis.

In [[heavy water reactor]]s the [[neutron moderator]] should preferably be low in {{chem|17|O}} and {{chem|18|O}} due to their higher neutron absorption cross section compared to {{chem|16|O}}. While this effect can also be observed in [[light water reactor]]s, ordinary hydrogen ([[protium (isotope)|protium]]) has a higher absorption cross section than any stable isotope of oxygen and its number density is twice as high in water as that of oxygen so that the effect is negligible. As some methods of [[isotope separation]] enrich not only heavier isotopes of hydrogen but also heavier isotopes of oxygen when producing [[heavy water]], the concentration of {{chem|17|O}} and {{chem|18|O}} can be measurably higher. Furthermore the {{chem|17|O}}(n,α){{chem|14|C| link=carbon-14}} reaction is a further undesirable result of an elevated concentration of heavier isotopes of oxygen. Therefore facilities which remove [[tritium]] from heavy water used in nuclear reactors often also remove or at least reduce the amount of heavier isotopes of oxygen.

Oxygen isotopes are also used to trace ocean composition and temperature which seafood is from.<ref>{{cite web|publisher=[[Phys.org]]|url=https://archive.ph/A3kVe|access-date=September 13, 2022|date=September 12, 2022|title=Using 'chemical fingerprinting' to fight seafood fraud and illegal fishing|doi=10.1111/faf.12703}}</ref>

==Radioisotopes==
Thirteen [[radioisotope]]s have been characterized; the most stable are {{SimpleNuclide|Oxygen|15}} with [[half-life]] {{val|122.266|(43)|u=s}} and {{SimpleNuclide|Oxygen|14}} with half-life {{val|70.621|(11)|u=s}}. All remaining radioisotopes have half-lives less than {{val|27|u=s}} and most have half-lives less than 0.1&nbsp;s. {{SimpleNuclide|Oxygen|24}} has half-life {{val|77.4|(4.5)|u=ms}}. The most common [[decay mode]] for isotopes lighter than the stable isotopes is [[positron emission|β<sup>+</sup> decay]] to [[nitrogen]], and the most common mode after is [[beta decay|β<sup>−</sup> decay]] to [[fluorine]].

===Oxygen-13===
Oxygen-13 is an unstable [[isotope]], with 8 protons and 5 neutrons. It has spin 3/2−, and [[half-life]] {{val|8.58|(5)|ul=ms}}. Its atomic mass is {{val|13.024815|(10)|ul=Da}}. It decays to [[Isotopes of nitrogen|nitrogen-13]] by electron capture, with a decay energy of {{val|17.770|(10)|ul=MeV}}. Its parent nuclide is [[Isotopes of fluorine|fluorine-14]].

===Oxygen-15===
Oxygen-15 is a radioisotope, often used in [[positron emission tomography]] (PET). It can be used in, among other things, [[15O-water|water]] for PET [[myocardial perfusion imaging]] and for [[brain]] imaging.<ref>{{cite journal|last1=Rischpler|first1=Christoph|last2=Higuchi|first2=Takahiro|last3=Nekolla|first3=Stephan G.|title=Current and Future Status of PET Myocardial Perfusion Tracers|journal=Current Cardiovascular Imaging Reports|date=22 November 2014|volume=8|issue=1|pages=333–343|doi=10.1007/s12410-014-9303-z|s2cid=72703962}}</ref><ref>{{cite book|last1=Kim|first1=E. Edmund|last2=Lee|first2=Myung-Chul|last3=Inoue|first3=Tomio|last4=Wong|first4=Wai-Hoi|title=Clinical PET and PET/CT: Principles and Applications|date=2012|publisher=Springer|isbn=9781441908025|page=182|url=https://books.google.com/books?id=jj9eHkn1tR0C&pg=PA182|language=en}}</ref> It has an atomic mass of {{val|15.0030656|(5)}}, and a [[half-life]] of {{val|122.266|(43)|u=s}}. It is produced through [[deuteron]] bombardment of [[nitrogen-14]] using a [[cyclotron]].<ref>{{cite web|title=Production of PET Radionuclides|url=http://www.petnm.unimelb.edu.au/pet/detail/radionuc.html|publisher=Austin Hospital, Austin Health|access-date=6 December 2012|url-status=dead|archive-url=https://archive.today/20130115012317/http://www.petnm.unimelb.edu.au/pet/detail/radionuc.html|archive-date=15 January 2013}}</ref>

Oxygen-15 and nitrogen-13 are produced in air when [[gamma ray]]s (for example from [[lightning]]) knock neutrons out of <sup>16</sup>O and <sup>14</sup>N:<ref>{{cite news|last1=Timmer|first1=John|title=Lightning strikes leave behind a radioactive cloud|url=https://arstechnica.com/science/2017/11/lightning-strikes-leave-behind-a-radioactive-cloud/|work=Ars Technica|date=25 November 2017|language=en-us}}</ref>
:{{SimpleNuclide|Oxygen|16}} + γ → {{SimpleNuclide|Oxygen|15}} + n
:{{SimpleNuclide|Nitrogen|14}} + γ → {{SimpleNuclide|Nitrogen|13}} + n
{{SimpleNuclide|Oxygen|15}} decays to {{SimpleNuclide|Nitrogen|15}}, emitting a [[positron]]. The positron quickly annihilates with an electron, producing two gamma rays of about 511&nbsp;keV. After a lightning bolt, this gamma radiation dies down with half-life 2&nbsp;min, but these low-energy gamma rays go on average only about 90 metres through the air. Together with rays produced from positrons from nitrogen-13 they may only be detected for a minute or so as the "cloud" of {{SimpleNuclide|Oxygen|15}} and {{SimpleNuclide|Oxygen|13}} floats by, carried by the wind.<ref>{{cite journal|last1=Teruaki Enoto|display-authors=etal|title=Photonuclear reactions triggered by lightning discharge|journal=Nature|volume=551|issue=7681|pages=481–484|date=Nov 23, 2017|doi=10.1038/nature24630|pmid=29168803|bibcode=2017Natur.551..481E|arxiv=1711.08044|s2cid=4388159}}</ref>

==See also==

* [[Dole effect]]

==References==
{{Reflist}}

*{{cite book|title=The Encyclopedia of the Chemical Elements|url=https://archive.org/details/encyclopediaofch00hamp|url-access=registration|last1=Cook|first1=Gerhard A.|last2=Lauer|first2= Carol M.|publisher=Reinhold Book Corporation|location=New York|year=1968|pages=[https://archive.org/details/encyclopediaofch00hamp/page/499 499–512]|editor=Clifford A. Hampel|chapter=Oxygen|lccn=68-29938}}
*{{cite book|title=Nature's Building Blocks: An A–Z Guide to the Elements|last=Emsley|first=John|publisher=Oxford University Press|year=2001|location=Oxford, England, UK|isbn=978-0-19-850340-8|chapter=Oxygen|pages=[https://archive.org/details/naturesbuildingb0000emsl/page/297 297–304]|chapter-url=https://archive.org/details/naturesbuildingb0000emsl/page/297}}
*{{cite book|last1=Parks|first1=G. D.|last2=Mellor|first2=J. W.|year=1939|title=Mellor's Modern Inorganic Chemistry|edition=6th|publisher=Longmans, Green and Co|location=London}}

{{Navbox element isotopes}}
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[[Category:Isotopes of oxygen| ]]
[[Category:Oxygen]]
[[Category:Lists of isotopes by element|Oxygen]]