View source for Isotopes of lithium

{{Short description|none}}
{{more citations needed|date=May 2018}}
{{Use dmy dates|date=June 2024}}
{{Infobox lithium isotopes}}

Naturally occurring [[lithium]] (<sub>3</sub>Li) is composed of two [[stable isotope ratio|stable isotopes]], lithium-6 (<sup>6</sup>Li) and lithium-7 (<sup>7</sup>Li), with the latter being far more abundant on Earth. Both of the natural [[isotope]]s have an unexpectedly low [[nuclear binding energy]] per [[nucleon]] ({{val|5332.3312|(3)|u=keV}} for <sup>6</sup>Li and {{val|5606.4401|(6)|u=keV}} for <sup>7</sup>Li) when compared with the adjacent lighter and heavier elements, [[helium]] ({{val|7073.9156|(4)|u=keV}} for helium-4) and [[beryllium]] ({{val|6462.6693|(85)|u=keV}} for beryllium-9). The longest-lived [[radionuclide|radioisotope]] of lithium is <sup>8</sup>Li, which has a [[half-life]] of just {{val|838.7|(3)|ul=milliseconds}}. <sup>9</sup>Li has a half-life of {{val|178.2|(4)|u=ms}}, and <sup>11</sup>Li has a half-life of {{val|8.75|(6)|u=ms}}. All of the remaining isotopes of lithium have half-lives that are shorter than 10 [[nanosecond]]s. The shortest-lived known isotope of lithium is <sup>4</sup>Li, which decays by [[proton emission]] with a half-life of about {{val|91|(9)|u=yoctoseconds}} ({{val|9.1|(9)|e=-23|u=s}}), although the half-life of <sup>3</sup>Li is yet to be determined, and is likely to be much shorter, like <sup>2</sup>He (helium-2, diproton) which undergoes proton emission within {{val||e=-9}} s.

Both <sup>7</sup>Li and <sup>6</sup>Li are two of the [[primordial nuclide]]s that were produced in the [[Big Bang nucleosynthesis|Big Bang]], with <sup>7</sup>Li to be 10<sup>−9</sup> of all primordial nuclides, and <sup>6</sup>Li around 10<sup>−13</sup>.<ref name="Primodal-lithium-problem-2012-arx">{{cite journal |arxiv=1203.3551 |doi=10.1146/annurev-nucl-102010-130445 | doi-access=free |title=The Primordial Lithium Problem |year=2011 |last1=Fields |first1=Brian D. |s2cid=119265528 |journal=[[Annual Review of Nuclear and Particle Science]] |volume=61 |issue=1 |pages=47–68 |bibcode=2011ARNPS..61...47F }}</ref> A small percentage of <sup>6</sup>Li is also known to be produced by [[nuclear reaction]]s in certain stars. The isotopes of lithium separate somewhat during a variety of [[geology|geological]] processes, including mineral formation (chemical precipitation and [[ion exchange]]). Lithium ions replace [[magnesium]] or [[iron]] in certain [[octahedron|octahedral locations]] in [[clay]]s, and lithium-6 is sometimes preferred over <sup>7</sup>Li. This results in some enrichment of <sup>6</sup>Li in geological processes.

In [[nuclear physics]], <sup>6</sup>Li is an important isotope, because when it is bombarded with [[neutron]]s, [[tritium]] is produced.

Both <sup>6</sup>Li and <sup>7</sup>Li isotopes show [[nuclear magnetic resonance]] effect, despite being quadrupolar (with nuclear spins of 1+ and 3/2−). <sup>6</sup>Li has sharper lines, but due to its lower abundance requires a more sensitive NMR-spectrometer. <sup>7</sup>Li is more abundant, but has broader lines because of its larger nuclear spin. The range of chemical shifts is the same of both nuclei and lies within +10 (for [[Lithium amide|LiNH<sub>2</sub>]] in liquid NH<sub>3</sub>) and −12 (for Li+ in [[fulleride]]).<ref>{{cite web | url=https://chem.ch.huji.ac.il/nmr/techniques/1d/row2/li.html | title=(Li) Lithium NMR }}</ref>

== List of isotopes ==
{{Anchor|Lithium-9}}

<!--Please delete anchor(s) from the list above or table below if adding a dedicated isotope section(s).-->

{{Isotopes table
|symbol=Li
|refs=NUBASE2020, AME2020 II
|notes=m, resonance, unc(), mass#, spin(), spin#, daughter-st, p, n, IT
}}
|-
| {{SimpleNuclide|Lithium|3}}<ref group="n">Discovery of this isotope is unconfirmed</ref>
| style="text-align:right" | 3
| style="text-align:right" | 0
| {{val|3.03078|(215)}}#
| 
| [[proton emission|p]] ?<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|Helium|2|link=yes}} ?
| 3/2−#
|
|
|-
| {{SimpleNuclide|Lithium|4}}
| style="text-align:right" | 3
| style="text-align:right" | 1
| {{val|4.02719|(23)}}
| {{val|91|(9)|u=ys}}<br />[{{val|5.06|(52)|u=MeV}}]
| p
| '''{{SimpleNuclide|Helium|3|link=yes}}'''
| 2−
|
|
|-
| {{SimpleNuclide|Lithium|5}}
| style="text-align:right" | 3
| style="text-align:right" | 2
| {{val|5.012540|(50)}}
| {{val|370|(30)|u=ys}}<br />[{{val|1.24|(10)|u=MeV}}]
| p
| '''{{SimpleNuclide|Helium|4|link=yes}}'''
| 3/2−
|
|
|-
| {{SimpleNuclide|Lithium|6}}<ref group="n">One of the few stable [[even and odd atomic nuclei#Odd proton, odd neutron|odd-odd nuclei]]</ref>
| style="text-align:right" | 3
| style="text-align:right" | 3
| {{val|6.0151228874|(15)}}
| colspan="3" style="text-align:center;"|'''Stable'''
| 1+
| style="text-align:center" colspan="2"|[{{val|0.019}}, {{val|0.078}}]<ref name="Atomic Weight of Lithiumb">{{Cite web|title=Atomic Weight of Lithium|url=https://ciaaw.org/lithium.htm|access-date=21 October 2021|website=ciaaw.org}}</ref>
|-id=Lithium-6m
| style="text-indent:1em" | {{SimpleNuclide|Lithium|6|m}}
| colspan="3" style="text-indent:2em" | {{val|3562.88|(10)|u=keV}}
| {{val|56|(14)|u=as}}
| [[Nuclear isomer#Decay processes|IT]]
| '''{{SimpleNuclide|Lithium|6|link=yes}}'''
| 0+
|
|
|-
| {{SimpleNuclide|Lithium|7}}<ref group="n">Produced in [[Big Bang nucleosynthesis]] and by [[cosmic ray spallation]]</ref>
| style="text-align:right" | 3
| style="text-align:right" | 4
| {{val|7.016003434|(4)}}
| colspan="3" style="text-align:center;"|'''Stable'''
| 3/2−
| colspan="2" style="text-align:center"|[{{val|0.922}}, {{val|0.981}}]<ref name="Atomic Weight of Lithiumb" />
|-
| {{SimpleNuclide|Lithium|8}}
| style="text-align:right" | 3
| style="text-align:right" | 5
| {{val|8.02248624|(5)}}
| {{val|838.7|(3)|u=ms}}
| β<sup>−</sup>
| {{SimpleNuclide|Beryllium|8|link=yes}}<ref group="n">Immediately decays into two [[alpha particle|α-particles]] for a net reaction of <sup>8</sup>Li → 2'''<sup>4</sup>He''' + e<sup>−</sup></ref>
| 2+
|
|
|-
| rowspan="2"|{{SimpleNuclide|Lithium|9}}
| rowspan="2" style="text-align:right" | 3
| rowspan="2" style="text-align:right" | 6
| rowspan="2"|{{val|9.02679019|(20)}}
| rowspan="2"|{{val|178.2|(4)|u=ms}}
| β<sup>−</sup>n ({{val|50.5|(1.0)|u=%}})
| {{SimpleNuclide|Beryllium|8|link=yes}}<ref group="n">Immediately decays into two α-particles for a net reaction of <sup>9</sup>Li → 2'''<sup>4</sup>He''' + <sup>1</sup>n + e<sup>−</sup></ref>
| rowspan="2"|3/2−
| rowspan="2"|
| rowspan="2"|
|-
| β<sup>−</sup> ({{val|49.5|(1.0)|u=%}})
| '''{{SimpleNuclide|Beryllium|9|link=yes}}'''
|-id=Lithium-10
| {{SimpleNuclide|Lithium|10}}
| style="text-align:right" | 3
| style="text-align:right" | 7
| {{val|10.035483|(14)}}
| {{val|2.0|(5)|u=zs}}<br />[{{val|0.2|(1.2)|u=MeV}}]
| n
| {{SimpleNuclide|Lithium|9|link=yes}}
| (1−, 2−)
|
|
|-id=Lithium-10m1
| style="text-indent:1em" | {{SimpleNuclide|Lithium|10|m1}}
| colspan="3" style="text-indent:2em" | {{val|200|(40)|u=keV}}
| {{val|3.7|(1.5)|u=zs}}
| IT
| {{SimpleNuclide|Lithium|10|link=yes}}
| 1+
|
|
|-id=Lithium-10m2
| style="text-indent:1em" | {{SimpleNuclide|Lithium|10|m2}}
| colspan="3" style="text-indent:2em" | {{val|480|(40)|u=keV}}
| {{val|1.35|(24)|u=zs}}<br />[{{val|0.350|(70)|u=MeV}}]
| IT
| {{SimpleNuclide|Lithium|10|link=yes}}
| 2+
|
|
|-
| rowspan=7|{{SimpleNuclide|Lithium|11}}<ref group="n">Has 2 [[halo nucleus|halo]] neutrons</ref>
| rowspan=7 style="text-align:right" | 3
| rowspan=7 style="text-align:right" | 8
| rowspan=7|{{val|11.0437236|(7)}}
| rowspan=7|{{val|8.75|(6)|u=ms}}
| β<sup>−</sup>n ({{val|86.3|(9)|u=%}})
| {{SimpleNuclide|Beryllium|10|link=yes}}
| rowspan=7|3/2−
| rowspan=7|
| rowspan=7|
|-
| β<sup>−</sup> ({{val|6.0|(1.0)|u=%}})
| {{SimpleNuclide|Beryllium|11|link=yes}}
|-
| β<sup>−</sup>2n ({{val|4.1|(4)|u=%}})
| '''{{SimpleNuclide|Beryllium|9|link=yes}}'''
|-
| β<sup>−</sup>3n ({{val|1.9|(2)|u=%}})
| {{SimpleNuclide|Beryllium|8|link=yes}}<ref group="n">Immediately decays into two '''<sup>4</sup>He''' atoms for a net reaction of <sup>11</sup>Li → 2'''<sup>4</sup>He''' + 3<sup>1</sup>n + e<sup>−</sup></ref>
|-
| β<sup>−</sup>α ({{val|1.7|(3)|u=%}})
| {{SimpleNuclide|Helium|7|link=yes}}
|-
| β<sup>−</sup>d ({{val|0.0130|(13)|u=%}})
| {{SimpleNuclide|Lithium|9|link=yes}}
|-
| β<sup>−</sup>t ({{val|0.0093|(8)|u=%}})
| {{SimpleNuclide|Lithium|8|link=yes}}
|-
| {{SimpleNuclide|Lithium|12}}
| style="text-align:right" | 3
| style="text-align:right" | 9
| {{val|12.05378|(107)}}#
| < 10 ns
| n ?<ref group="n" name="decay mode 1" />
| {{SimpleNuclide|Lithium|11|link=yes}} ?
| (1−, 2−)
|
|
|-id=Lithium-13
| {{SimpleNuclide|Lithium|13}}
| style="text-align:right" | 3
| style="text-align:right" | 10
| {{val|13.061170|(80)}}
| {{val|3.3|(1.2)|u=zs}}<br />[{{val|0.2|(9.2)|u=MeV}}]
| 2n
| {{SimpleNuclide|Lithium|11|link=yes}}
| 3/2−#
|
|
{{Isotopes table/footer}}

== Isotope separation ==
=== Colex separation ===
{{Main|COLEX process}}Lithium-6 has a greater affinity than lithium-7 for the [[Chemical element|element]] [[mercury (element)|mercury]]. When an amalgam of lithium and mercury is added to solutions containing [[lithium hydroxide]], the lithium-6 becomes more concentrated in the amalgam and the lithium-7 more in the hydroxide solution.

The colex ('''col'''umn '''ex'''change) separation method makes use of this by passing a counter-flow of amalgam and hydroxide through a cascade of stages. The [[Fraction (chemistry)|fraction]] of lithium-6 is preferentially drained by the mercury, but the lithium-7 flows mostly with the hydroxide.
At the bottom of the column, the lithium (enriched with lithium-6) is separated from the amalgam, and the mercury is recovered to be reused with fresh [[raw material]]. At the top, the lithium hydroxide solution is [[electrolysis|electrolyzed]] to liberate the lithium-7 fraction. The enrichment obtained with this method varies with the column length and the flow speed.

=== Other methods ===
In the vacuum distillation technique, lithium is heated to a temperature of about {{val|550|ul=degC}} in a [[vacuum]]. Lithium atoms evaporate from the liquid surface and are collected on a cold surface positioned a few centimetres above the liquid surface.<ref>{{Cite journal |last1=Katal'nikov |first1=S. G. |last2=Andreev |first2=B. M. |date=1 March 1962 |title=The separation factor of lithium isotopes during vacuum distillation |url=https://doi.org/10.1007/BF01491187 |journal=The Soviet Journal of Atomic Energy |language=en |volume=11 |issue=3 |pages=889–893 |doi=10.1007/BF01491187 |s2cid=96799991 |issn=1573-8205|url-access=subscription }}</ref> Since lithium-6 atoms have a greater [[mean free path]], they are collected preferentially. The theoretical separation efficiency of this method is about 8.0 percent. A multistage process may be used to obtain higher degrees of separation.

The isotopes of lithium, in principle, can also be separated through electrochemical method and distillation chromatography, which are currently in development.<ref>{{Cite journal |last1=Badea |first1=Silviu-Laurentiu |last2=Niculescu |first2=Violeta-Carolina |last3=Iordache |first3=Andreea-Maria |date=April 2023 |title=New Trends in Separation Techniques of Lithium Isotopes: A Review of Chemical Separation Methods |journal=Materials |language=en |volume=16 |issue=10 |pages=3817 |doi=10.3390/ma16103817 |pmid=37241444 |pmc=10222844 |bibcode=2023Mate...16.3817B |issn=1996-1944 |doi-access=free }}</ref>

== Lithium-3 ==
'''Lithium-3''', also known as the '''triproton''', would consist of three [[proton]]s and zero [[neutron]]s. It was reported as [[nuclear drip line|proton unbound]] in 1969, but this result was not accepted and its existence is thus unproven.{{NUBASE2016|ref|page=030001–21}} No other [[resonance (particle physics)|resonances]] attributable to {{SimpleNuclide|Lithium|3}} have been reported, and it is expected to decay by prompt [[proton emission]] (much like the [[Isotopes of helium#Helium-2 (diproton)|diproton]], {{SimpleNuclide|Helium|2}}).<ref>{{cite journal |last1=Purcell |first1=J. E. |last2=Kelley |first2=J. H. |last3=Kwan |first3=E. |last4=Sheu |first4=C. G. |last5=Weller |first5=H. R. |title=Energy Levels of Light Nuclei (''A''&nbsp;=&nbsp;3) |journal=[[Nuclear Physics A]] |volume=848 |date=2010 |issue=1 |page=1 |doi=10.1016/j.nuclphysa.2010.08.012 |bibcode=2010NuPhA.848....1P |url=http://www.tunl.duke.edu/nucldata/ourpubs/03_2010.pdf |access-date=3 January 2020 |archive-date=1 February 2018 |archive-url=https://web.archive.org/web/20180201093026/http://www.tunl.duke.edu/nucldata/ourpubs/03_2010.pdf |url-status=dead }}</ref>

== Lithium-4 ==
'''Lithium-4''' contains three protons and one neutron. It is the shortest-lived known isotope of lithium, with a half-life of {{val|91|(9)|u=yoctoseconds}} ({{val|9.1|e=-23|(9)|u=s}}) and decays by proton emission to [[helium-3]].<ref name="Isotopes of Lithium">{{cite web| url=http://periodictable.com/Isotopes/003.4/index2.full.dm.html| title=Isotopes of Lithium| access-date=20 October 2013}}</ref> Lithium-4 can be formed as an intermediate in some [[nuclear fusion]] reactions.

== Lithium-5 ==
[[File:Cross_Section_for_Fusion_reactions.png|thumb|Fusion cross sections of major reactions. Without the resonance in lithium-5, the D-3He reaction would have a far lower cross section.]]
Lithium-5 is very short-lived with a half-life of 370(30) yoctoseconds, decaying via proton emission to helium-4. It is formed as an intermediate in the fusion of [[deuterium]] and [[helium-3]]:

<math>{}^2\mathrm{D} + {}^3\mathrm{He} \longrightarrow {}^5\mathrm{Li}^{*} \longrightarrow {}^4\mathrm{He} + p + 18.4\ \mathrm{MeV} </math>

The reaction is greatly enhanced by the existence of a resonance. Lithium-5, which has a natural spin state of −3/2 at the 0 MeV ground state, has a +3/2 excited spin state at 16.66 MeV. Because the reaction creates lithium-5 nuclei with an energy level close to this state, it happens more frequently. A symmetrical resonance in the [[helium-5]] nucleus makes the [[deuterium–tritium fusion]] reaction the most favourable known.<ref name="q517">{{cite journal |last=Barker |first=FC |last2=Woods |first2=CL |year=1985 |title=States of 5He and 5Li |url=https://www.publish.csiro.au/ph/pdf/ph850563 |journal=Australian Journal of Physics |publisher=CSIRO Publishing |volume=38 |issue=4 |page=563 |doi=10.1071/ph850563 |issn=0004-9506 |access-date=2025-04-10 |doi-access=free}}</ref>

== Lithium-6 ==
'''Lithium-6''' is valuable as the source material for the production of [[tritium]] (hydrogen-3) and as an absorber of neutrons in [[nuclear fusion]] reactions. Between 1.9% and 7.8% of terrestrial lithium  in normal materials consists of lithium-6, with the rest being lithium-7. Large amounts of lithium-6 have been separated out for placing into [[thermonuclear weapon]]s. The separation of lithium-6 has by now ceased in the large [[thermonuclear fusion|thermonuclear]] powers{{Citation needed|reason=Uncited claim, China is known to officially practise isotopic lithium separation via the COLEX process. Russia is also known to isotopically separate lithium, as well as possibly the DPRK.|date=April 2018}}, but stockpiles of it remain in these countries.

The [[deuterium–tritium fusion]] reaction has been investigated as a possible energy source, as it is currently the only fusion reaction with sufficient energy output for feasible implementation. In this scenario, lithium enriched in lithium-6 would be required to generate the necessary quantities of tritium. Mineral and brine lithium resources are a potential limiting factor in this scenario, but seawater can eventually also be used.<ref name="dtf">{{cite journal |last1=Bradshaw |first1=A.M. |last2=Hamacher |first2=T. |last3=Fischer |first3=U. |date=2010 |title=Is nuclear fusion a sustainable energy form? |journal=[[Fusion Engineering and Design]] |volume=86 |issue=9 |pages=2770–2773 |doi=10.1016/j.fusengdes.2010.11.040 |hdl=11858/00-001M-0000-0026-E9D2-6 |s2cid=54674085 |url=https://th.fhi-berlin.mpg.de/th/publications/FusionEngDesign-2011-2770-2011.pdf|hdl-access=free }}</ref> [[Pressurized heavy-water reactor]]s such as the [[CANDU]] produce small quantities of tritium in their coolant/moderator from neutron absorption and this is sometimes extracted as an alternative to the use of lithium-6.

Lithium-6 is one of only four stable isotopes with a [[Spin (physics)|spin]] of 1, the others being [[deuterium]], [[boron-10]], and [[Isotopes of nitrogen#Nitrogen-14|nitrogen-14]],<ref>{{cite book | last= Chandrakumar | first= N. | date= 2012 | title= Spin-1 NMR | publisher= Springer Science & Business Media | page= 5 | isbn= 9783642610899 | url= https://books.google.com/books?id=gVHmCAAAQBAJ&pg=PA5}}</ref> and has the smallest nonzero nuclear electric [[quadrupole]] moment of any stable nucleus.

In 2025, researchers from [[ETH Zürich]] and [[Texas A&M University]] introduced a mercury-free method for isolating lithium-6, providing an alternative to the [[COLEX process]], which uses toxic liquid mercury. This technique was discovered by accident during [[water purification]] research and utilized zeta-vanadium oxide (ζ-V2O5) to selectively trap lithium-6 ions, which could be a crucial step in scaling up the production of fusion-grade lithium-6, potentially unlocking more cost-effective and safer ways to isolate lithium for nuclear fusion reactors.<ref>{{cite journal |last=Luis Carrillo |first=J. |display-authors=et al. |title=Electrochemical 6Li isotope enrichment based on selective insertion in 1D tunnel-structured V2O5 |journal=Cell |date=20 March 2025 |doi=10.1016/j.chempr.2025.102486 }}</ref>

== Lithium-7 ==
'''Lithium-7''' is by far the most abundant isotope of lithium, making up between 92.2% and 98.1% of all terrestrial lithium. A lithium-7 atom contains three protons, four neutrons, and three electrons. Because of its nuclear properties, lithium-7 is less common than [[helium]], [[carbon]], [[nitrogen]], or [[oxygen]] in the Universe, even though the latter three all have heavier [[Atomic nucleus|nuclei]]. The [[Castle Bravo]] thermonuclear test greatly exceeded its expected yield due to incorrect assumptions about the nuclear properties of lithium-7.

The industrial production of lithium-6 results in a waste product which is enriched in lithium-7 and depleted in lithium-6. This material has been sold commercially, and some of it has been released into the environment. A relative abundance of lithium-7, as high as 35 percent greater than the natural value, has been measured in the ground water in a carbonate aquifer underneath the West Valley Creek in [[Pennsylvania]], which is downstream from a lithium processing plant. The isotopic composition of lithium in normal materials can vary somewhat depending on its origin, which determines its relative atomic mass in the source material. An accurate relative atomic mass for samples of lithium cannot be measured for all sources of lithium.<ref>Coplen, Tyler B.; Hopple, J. A.; Böhlke, John Karl; Peiser, H. Steffen; Rieder, S. E.; Krouse, H. R.; Rosman, Kevin J. R.; Ding, T.; Vocke, R. D., Jr.; Révész, K. M.; Lamberty, A.; Taylor, Philip D. P.; De Bièvre, Paul; "Compilation of minimum and maximum isotope ratios of selected elements in naturally occurring terrestrial materials and reagents", ''U.S. Geological Survey Water-Resources Investigations Report'' 01-4222 (2002). As quoted in {{cite journal |title=Isotope-Abundance Variations of Selected Elements (IUPAC technical report) |author=T. B. Coplen |s2cid=97223816 |journal=Pure and Applied Chemistry |volume=74 |issue=10 |pages=1987–2017 |year=2002 |url=http://pac.iupac.org/publications/pac/pdf/2002/pdf/7410x1987.pdf |display-authors=etal |doi=10.1351/pac200274101987 |access-date=29 October 2012 |archive-date=3 March 2016 |archive-url=https://web.archive.org/web/20160303202428/http://pac.iupac.org/publications/pac/pdf/2002/pdf/7410x1987.pdf |url-status=dead }}</ref>

Lithium-7 is used as a part of the molten [[lithium fluoride]] in [[molten-salt reactor]]s: [[Fluoride|liquid-fluoride]] [[nuclear reactor]]s. The large [[neutron cross section|neutron absorption cross section]] of lithium-6 (about 940 [[barn (unit)|barns]]<ref>
{{cite journal
 | first= Norman E.
 | last= Holden
 | title= The Impact of Depleted <sup>6</sup>Li on the Standard Atomic Weight of Lithium
 | date= January–February 2010
 | journal=Chemistry International
 | publisher= [[International Union of Pure and Applied Chemistry]]
 | url= http://www.iupac.org/publications/ci/2010/3201/3_holden.html
 | access-date= 6 May 2014
}}
</ref>)
as compared with the very small neutron cross section of lithium-7 (about 45 [[Barn (unit)#Commonly used prefixed versions|millibarns]]) makes high separation of lithium-7 from natural lithium a strong requirement for the possible use in lithium fluoride reactors.

[[Lithium hydroxide|Lithium-7 hydroxide]] is used for alkalizing of the coolant in [[pressurized water reactor]]s.<ref>[http://www.gao.gov/products/GAO-13-716 Managing Critical Isotopes: Stewardship of Lithium-7 Is Needed to Ensure a Stable Supply, GAO-13-716] // [[Government Accountability Office|U.S. Government Accountability Office]], 19 September 2013; [http://www.gao.gov/assets/660/657964.pdf pdf]</ref>

Some lithium-7 has been produced, for a few picoseconds, which contains a [[lambda baryon|lambda particle]] in its nucleus, whereas an atomic nucleus is generally thought to contain only neutrons and protons.<ref name="Emsley2001">{{cite book |first=John |last=Emsley |title=Nature's Building Blocks: An A-Z Guide to the Elements |year=2001 |publisher=Oxford University Press |isbn=978-0-19-850340-8 |pages=234–239 |url=https://books.google.com/books?id=j-Xu07p3cKwC&pg=PA239 }}</ref><ref>{{cite magazine |first=Geoff |last=Brumfiel |title=The Incredible Shrinking Nucleus |magazine=Physical Review Focus |date=1 March 2001 |volume=7 |doi=10.1103/PhysRevFocus.7.11 }}</ref>

== Lithium-8 ==
'''Lithium-8''' has been proposed as a source of 6.4&nbsp;MeV electron [[neutrino|antineutrinos]] generated by the inverse beta decay to beryllium-8. The ISODAR [[particle physics]] collaboration describes a scheme to generate lithium-8 for immediate decay by bombarding stable lithium-7 with 60&nbsp;MeV protons created by a [[cyclotron]] [[particle accelerator]].<ref>{{Cite journal |last1=Bungau |first1=Adriana |last2=Alonso |first2=Jose |last3=Bartoszek |first3=Larry |last4=Conrad |first4=Janet |date=May 2018 |title=Optimizing the <sup>8</sup>Li yield for the IsoDAR Neutrino Experiment |journal=Journal of Instrumentation |volume=14 |issue=3 |pages=03001 |doi=10.1088/1748-0221/14/03/P03001 |arxiv=1805.00410|s2cid=55756525 }}</ref>

== Lithium-11 ==
'''Lithium-11''' is a [[halo nucleus]] consisting of a lithium-9 core surrounded by two loosely-bound neutrons; both neutrons must be present in order for this system to be bound, which has led to the description as a "[[Borromean nucleus]]".<ref>{{cite web | url=https://www.sciencenews.org/article/rare-isotope-elements-new-particle-accelerator-atom-nucleus | title=A new particle accelerator aims to unlock secrets of bizarre atomic nuclei | date=15 November 2021 }}</ref> While the proton [[root-mean-square]] radius of <sup>11</sup>Li is {{val|2.18|0.16|0.21|u=fm}}, its neutron radius is much larger at {{val|3.34|0.02|0.08|u=fm}}; for comparison, the corresponding figures for <sup>9</sup>Li are {{val|2.076|0.037|u=fm}} for the protons and {{val|2.4|0.03|u=fm}} for the neutrons.<ref>{{cite journal |last1=Moriguchi |first1=T. |last2=Ozawa |first2=A. |last3=Ishimoto |first3=S. |last4=Abe |first4=Y. |last5=Fukuda |first5=M. |last6=Hachiuma |first6=I. |last7=Ishibashi |first7=Y. |last8=Ito |first8=Y. |last9=Kuboki |first9=T. |last10=Lantz |first10=M. |last11=Nagae |first11=D. |last12=Namihira |first12=K. |last13=Nishimura |first13=D. |last14=Ohtsubo |first14=T. |last15=Ooishi |first15=H. |last16=Suda |first16=T. |last17=Suzuki |first17=H. |last18=Suzuki |first18=T. |last19=Takechi |first19=M. |last20=Tanaka |first20=K. |last21=Yamaguchi |first21=T. |title=Density distributions of 11 Li deduced from reaction cross-section measurements |journal=Physical Review C |date=16 August 2013 |volume=88 |issue=2 |page=024610 |doi=10.1103/PhysRevC.88.024610 |bibcode=2013PhRvC..88b4610M |url=https://www.researchgate.net/publication/258026116}}</ref> It decays by [[beta emission]] and [[neutron emission]] to [[beryllium-10|{{SimpleNuclide|Beryllium|10}}]], [[Isotopes of beryllium|{{SimpleNuclide|Beryllium|11}}]], or [[Isotopes of beryllium|{{SimpleNuclide|Beryllium|9}}]] (see tables above and below). Having a [[magic number (physics)|magic number]] of 8 neutrons, lithium-11 sits on the first of five known [[islands of inversion]], which explains its longer half-life compared to adjacent nuclei.<ref>{{cite journal |last1=Brown |first1=B. Alex |title=Islands of insight in the nuclear chart |url=https://physics.aps.org/articles/v3/104 |journal=Physics |pages=104 |language=en |doi=10.1103/PhysRevLett.105.252501 |date=13 December 2010|volume=3 |issue=25 |pmid=21231582 |arxiv=1010.3999 |s2cid=43334780 }}</ref>

== Lithium-12 ==
'''Lithium-12''' has a considerably shorter half-life. It decays by neutron emission into {{SimpleNuclide|Lithium|11}}, which decays as mentioned above.

== Decay chains ==
While β<sup>−</sup> decay into [[isotopes of beryllium]] (often combined with single- or multiple-neutron emission) is predominant in heavier isotopes of lithium, {{SimpleNuclide|Lithium|10}} and {{SimpleNuclide|Lithium|12}} decay via neutron emission into {{SimpleNuclide|Lithium|9}} and {{SimpleNuclide|Lithium|11}} respectively due to their positions beyond the neutron [[nuclear drip line|drip line]]. Lithium-11 has also been observed to decay via multiple forms of fission. Isotopes lighter than {{SimpleNuclide|Lithium|6}} decay into [[isotopes of helium]] exclusively by proton emission, as they are beyond the proton drip line. The decay modes of the two isomers of {{SimpleNuclide|Lithium|10}} are unknown.
:<math chem>\begin{array}{l}{}\\
\ce{^4_3Li ->[91~\ce{ys}] {^3_2He} + {^1_1H}} \\
\ce{^5_3Li ->[370~\ce{ys}] {^4_2He} + {^1_1H}} \\
\ce{^8_3Li ->[838.7~\ce{ms}] {^8_4Be} + e^-} \\
\ce{^9_3Li ->[178.2~\ce{ms}] {^8_4Be} + {^1_0n} + e^-} \\
\ce{^9_3Li ->[178.2~\ce{ms}] {^9_4Be} + e^-} \\
\ce{^{10}_3Li ->[2~\ce{zs}] {^9_3Li} + {^1_0n}} \\
\ce{^{11}_3Li ->[8.75~\ce{ms}] {^{10}_4Be} + {^1_0n} + e^-} \\
\ce{^{11}_3Li ->[8.75~\ce{ms}] {^{11}_4Be} + e^-} \\
\ce{^{11}_3Li ->[8.75~\ce{ms}] {^9_4Be} + 2{^1_0n} + e^-} \\
\ce{^{11}_3Li ->[8.75~\ce{ms}] {^8_4Be} + 3{^1_0n} + e^-} \\
\ce{^{11}_3Li ->[8.75~\ce{ms}] {^7_2He} + {^4_2He} + e^-} \\
\ce{^{11}_3Li ->[8.75~\ce{ms}] {^8_3Li} + {^3_1H} + e^-} \\
\ce{^{11}_3Li ->[8.75~\ce{ms}] {^9_3Li} + {^2_1H} + e^-} \\
\ce{^{12}_3Li -> {^{11}_3Li} + {^1_0n}} \\{}
\end{array}</math>

== See also ==
* [[Cosmological lithium problem]]
* {{annotated link|Dilithium}}
* [[Halo nucleus]]
* {{annotated link|Lithium burning}}

== References ==
{{Reflist}}

== External links ==
{{Cite journal |last1=Lewis |first1=G. N. |last2=MacDonald |first2=R. T. |doi=10.1021/ja01303a045 |title=The Separation of Lithium Isotopes |journal=Journal of the American Chemical Society |volume=58 |issue=12 |pages=2519–2524 |year=1936 |bibcode=1936JAChS..58.2519L }}

{{Navbox element isotopes}}

[[Category:Isotopes of lithium| ]]
[[Category:Lithium]]
[[Category:Lists of isotopes by element|Lithium]]