Isotopes of xenon

Naturally occurring xenon (Xe) is made of eight stable isotopes and one very long-lived isotope. (¹²⁴Xe, ¹²⁶Xe, and ¹³⁴Xe are predicted to undergo double beta decay, but this has never been observed in these isotopes, so they are considered to be stable.)^[1][2] Xenon has the second highest number of stable isotopes. Only tin, with 10 stable isotopes, has more.^[3] Beyond these stable forms, there are over 30 unstable isotopes and isomers that have been studied, the longest-lived of which is ¹³⁶Xe, which undergoes double beta decay with a half-life of 2.165 ± 0.016(stat) ± 0.059(sys) ×10²¹ years^[4] with the next longest lived being ¹²⁷Xe with a half-life of 36.345 days. Of known isomers, the longest-lived is ^131mXe with a half-life of 11.934 days. ¹²⁹Xe is produced by beta decay of ¹²⁹I (half-life: 16 million years); ^131mXe, ¹³³Xe, ^133mXe, and ¹³⁵Xe are some of the fission products of both ²³⁵U and ²³⁹Pu, and therefore used as indicators of nuclear explosions.

The artificial isotope ¹³⁵Xe is of considerable significance in the operation of nuclear fission reactors. ¹³⁵Xe has a huge cross section for thermal neutrons, 2.65×10⁶ barns, so it acts as a neutron absorber or "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).

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 or fissioning of uranium in cooling water. The concentrations of these isotopes are still usually low compared to the naturally occurring radioactive noble gas ²²²Rn.

Because xenon is a tracer for two parent isotopes, Xe isotope ratios in meteorites are a powerful tool for studying the formation of the solar system. The I-Xe method of dating gives the time elapsed between nucleosynthesis and the condensation of a solid object from the solar nebula (Xenon being a gas, only that part of it that formed after condensation will be present inside the object). Xenon isotopes are also a powerful tool for understanding terrestrial differentiation. Excess ¹²⁹Xe found in carbon dioxide well gases from New Mexico was believed to be from the decay of mantle-derived gases soon after Earth's formation.^[5]

Relative atomic mass: 131.293(6).

All other isotopes have half-lives less than 12 days, most less than 20 hours. The shortest-lived isotope is ¹⁴⁸Xe with a half-life of 408 ns. Its 41 isotopes have mass numbers ranging from 108 to 148.

¹⁰⁸Xe (disc. 2011) is the second heaviest nuclide with equal numbers of protons and neutrons, after ¹¹²Ba.

Xenon-133

Isotopes of xenon Full table
General
Name, symbol	Isotopes of xenon,^133Xe
Neutrons	79
Protons	54
Nuclide data
Natural abundance	syn
Half-life	5.243 d (1)
Decay products	^133Cs
Isotope mass	132.9059107 u
Spin	3/2+
Decay mode	Decay energy
Beta^−	0.427 MeV

Xenon-133 (sold as a drug under the brand name Xeneisol, ATC code V09EX03 (WHO)) is an isotope of xenon. It is a radionuclide that is inhaled to assess pulmonary function, and to image the lungs.^[6] It is also used to image blood flow, particularly in the brain.^{[7] 133}Xe is also an important fission product.

Xenon-135

Xenon-135 is a radioactive isotope of xenon, produced as a fission product of uranium. It has a half-life of about 9.2 hours and is the most powerful known neutron-absorbing nuclear poison (having a neutron absorption cross-section of 2 million barns^[8]). The overall yield of xenon-135 from fission is 6.3%, though most of this results from the radioactive decay of fission-produced tellurium-135 and iodine-135. Xe-135 exerts a significant effect on nuclear reactor operation (xenon pit).

Xenon-136

Xenon-136 is an isotope of xenon that undergoes double beta decay to Barium-136 with a very long half life of 2.11×10²¹ years, more than ten orders of magnitude longer than the age of the universe ((13.799±0.021)×10⁹ years).

Table

nuclide symbol	Z(p)	N(n)	isotopic mass (u)	half-life	decay mode(s)[9][n 1]	daughter isotope(s)[n 2]	nuclear spin	representative isotopic composition (mole fraction)	range of natural variation (mole fraction)
	excitation energy
^110Xe	54	56	109.94428(14)	310(190) ms [105(+35−25) ms]	β^+	^110I	0+
					α	^106Te
^111Xe	54	57	110.94160(33)#	740(200) ms	β^+ (90%)	^111I	5/2+#
					α (10%)	^107Te
^112Xe	54	58	111.93562(11)	2.7(8) s	β^+ (99.1%)	^112I	0+
					α (.9%)	^108Te
^113Xe	54	59	112.93334(9)	2.74(8) s	β^+ (92.98%)	^113I	(5/2+)#
					β^+, p (7%)	^112Te
					α (.011%)	^109Te
					β^+, α (.007%)	^109Sb
^114Xe	54	60	113.927980(12)	10.0(4) s	β^+	^114I	0+
^115Xe	54	61	114.926294(13)	18(4) s	β^+ (99.65%)	^115I	(5/2+)
					β^+, p (.34%)	^114Te
					β^+, α (3×10^−4%)	^111Sb
^116Xe	54	62	115.921581(14)	59(2) s	β^+	^116I	0+
^117Xe	54	63	116.920359(11)	61(2) s	β^+ (99.99%)	^117I	5/2(+)
					β^+, p (.0029%)	^116Te
^118Xe	54	64	117.916179(11)	3.8(9) min	β^+	^118I	0+
^119Xe	54	65	118.915411(11)	5.8(3) min	β^+	^119I	5/2(+)
^120Xe	54	66	119.911784(13)	40(1) min	β^+	^120I	0+
^121Xe	54	67	120.911462(12)	40.1(20) min	β^+	^121I	(5/2+)
^122Xe	54	68	121.908368(12)	20.1(1) h	β^+	^122I	0+
^123Xe	54	69	122.908482(10)	2.08(2) h	EC	^123I	1/2+
^123mXe	185.18(22) keV			5.49(26) µs			7/2(−)
^124Xe	54	70	123.905893(2)	Observationally Stable[n 3]			0+	9.52(3)×10^−4
^125Xe	54	71	124.9063955(20)	16.9(2) h	β^+	^125I	1/2(+)
^125m1Xe	252.60(14) keV			56.9(9) s	IT	^125Xe	9/2(−)
^125m2Xe	295.86(15) keV			0.14(3) µs			7/2(+)
^126Xe	54	72	125.904274(7)	Observationally Stable[n 4]			0+	8.90(2)×10^−4
^127Xe	54	73	126.905184(4)	36.345(3) d	EC	^127I	1/2+
^127mXe	297.10(8) keV			69.2(9) s	IT	^127Xe	9/2−
^128Xe	54	74	127.9035313(15)	Stable[n 5]			0+	0.019102(8)
^129Xe[n 6]	54	75	128.9047794(8)	Stable[n 5]			1/2+	0.264006(82)
^129mXe	236.14(3) keV			8.88(2) d	IT	^129Xe	11/2−
^130Xe	54	76	129.9035080(8)	Stable[n 5]			0+	0.040710(13)
^131Xe[n 7]	54	77	130.9050824(10)	Stable[n 5]			3/2+	0.212324(30)
^131mXe	163.930(8) keV			11.934(21) d	IT	^131Xe	11/2−
^132Xe[n 7]	54	78	131.9041535(10)	Stable[n 5]			0+	0.269086(33)
^132mXe	2752.27(17) keV			8.39(11) ms	IT	^132Xe	(10+)
^133Xe[n 7][n 8]	54	79	132.9059107(26)	5.2475(5) d	β^−	^133Cs	3/2+
^133mXe	233.221(18) keV			2.19(1) d	IT	^133Xe	11/2−
^134Xe[n 7]	54	80	133.9053945(9)	Observationally Stable[n 9]			0+	0.104357(21)
^134m1Xe	1965.5(5) keV			290(17) ms	IT	^134Xe	7−
^134m2Xe	3025.2(15) keV			5(1) µs			(10+)
^135Xe[n 10]	54	81	134.907227(5)	9.14(2) h	β^−	^135Cs	3/2+
^135mXe	526.551(13) keV			15.29(5) min	IT (99.99%)	^135Xe	11/2−
					β^− (.004%)	^135Cs
^136Xe[n 11]	54	82	135.907219(8)	2.165(0.016 (stat), 0.059 (sys))×10^21 y[4]	β^−β^−	^136Ba	0+	0.088573(44)
^136mXe	1891.703(14) keV			2.95(9) µs			6+
^137Xe	54	83	136.911562(8)	3.818(13) min	β^−	^137Cs	7/2−
^138Xe	54	84	137.91395(5)	14.08(8) min	β^−	^138Cs	0+
^139Xe	54	85	138.918793(22)	39.68(14) s	β^−	^139Cs	3/2−
^140Xe	54	86	139.92164(7)	13.60(10) s	β^−	^140Cs	0+
^141Xe	54	87	140.92665(10)	1.73(1) s	β^− (99.45%)	^141Cs	5/2(−#)
					β^−, n (.043%)	^140Cs
^142Xe	54	88	141.92971(11)	1.22(2) s	β^− (99.59%)	^142Cs	0+
					β^−, n (.41%)	^141Cs
^143Xe	54	89	142.93511(21)#	0.511(6) s	β^−	^143Cs	5/2−
^144Xe	54	90	143.93851(32)#	0.388(7) s	β^−	^144Cs	0+
					β^−, n	^143Cs
^145Xe	54	91	144.94407(32)#	188(4) ms	β^−	^145Cs	(3/2−)#
^146Xe	54	92	145.94775(43)#	146(6) ms	β^−	^146Cs	0+
^147Xe	54	93	146.95356(43)#	130(80) ms [0.10(+10−5) s]	β^−	^147Cs	3/2−#
					β^−, n	^146Cs

1. Abbreviations:
   EC: Electron capture
   IT: Isomeric transition
2. Bold for stable isotopes
3. Suspected of undergoing β⁺β⁺ decay to ¹²⁴Te with a half-life over 48×10¹⁵ years
4. Suspected of undergoing β⁺β⁺ decay to ¹²⁶Te
5. Theoretically capable of spontaneous fission
6. Used in a method of radiodating groundwater and to infer certain events in the Solar System's history
7. Fission product
8. Has medical uses
9. Suspected of undergoing β⁻β⁻ decay to ¹³⁴Ba with a half-life over 11×10¹⁵ years
10. Most powerful known neutron absorber, produced in nuclear power plants as a decay product of ¹³⁵I, itself a decay product of ¹³⁵Te, a fission product. Normally absorbs neutrons in the high neutron flux environments to become ¹³⁶Xe; see iodine pit for more information
11. Primordial radionuclide

Notes

• The isotopic composition refers to that in air.
• Geologically exceptional samples are known in which the isotopic composition lies outside the reported range. The uncertainty in the atomic mass may exceed the stated value for such specimens.
• Commercially available materials may have been subjected to an undisclosed or inadvertent isotopic fractionation. Substantial deviations from the given mass and composition can occur.
• Values marked # are not purely derived from experimental data, but at least partly from systematic trends. Spins with weak assignment arguments are enclosed in parentheses.
• Uncertainties are given in concise form in parentheses after the corresponding last digits. Uncertainty values denote one standard deviation, except isotopic composition and standard atomic mass from IUPAC, which use expanded uncertainties.

References

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2. A. S. Barabash (April 2002). "Average (Recommended) Half-Life Values for Two-Neutrino Double-Beta Decay". Czechoslovak Journal of Physics. 52 (4): 567–573. doi:10.1023/A:1015369612904.
3. Rajam, J. B. (1960). Atomic Physics (7th ed.). Delhi: S. Chand and Co. ISBN 81-219-1809-X.
4. Albert, J. B.; Auger, M.; Auty, D. J.; Barbeau, P. S.; Beauchamp, E.; Beck, D.; Belov, V.; Benitez-Medina, C.; Bonatt, J.; Breidenbach, M.; Brunner, T.; Burenkov, A.; Cao, G. F.; Chambers, C.; Chaves, J.; Cleveland, B.; Cook, S.; Craycraft, A.; Daniels, T.; Danilov, M.; Daugherty, S. J.; Davis, C. G.; Davis, J.; Devoe, R.; Delaquis, S.; Dobi, A.; Dolgolenko, A.; Dolinski, M. J.; Dunford, M.; et al. (2014). "Improved measurement of the 2νββ half-life of ¹³⁶Xe with the EXO-200 detector". Physical Review C. 89. doi:10.1103/PhysRevC.89.015502.
5. Boulos, M. S.; Manuel, O. K. (1971). "The xenon record of extinct radioactivities in the Earth.". Science. 174 (4016): 1334–1336. Bibcode:1971Sci...174.1334B. doi:10.1126/science.174.4016.1334. PMID 17801897.
6. Jones, R. L.; Sproule, B. J.; Overton, T. R. (1978). "Measurement of regional ventilation and lung perfusion with Xe-133". Journal of nuclear medicine. 19 (10): 1187–1188. PMID 722337.
7. Hoshi, H.; Jinnouchi, S.; Watanabe, K.; Onishi, T.; Uwada, O.; Nakano, S.; Kinoshita, K. (1987). "Cerebral blood flow imaging in patients with brain tumor and arterio-venous malformation using Tc-99m hexamethylpropylene-amine oxime--a comparison with Xe-133 and IMP". Kaku Igaku. 24 (11): 1617–1623. PMID 3502279.
8. Chart of the Nuclides 13th Edition
9. "Universal Nuclide Chart". nucleonica. (registration required (help)).

• Isotope masses from Ame2003 Atomic Mass Evaluation by G. Audi, A. H. Wapstra, C. Thibault, J. Blachot and O. Bersillon in Nuclear Physics A729 (2003).
• Isotopic compositions and standard atomic masses from:
  • J. R. de Laeter; J. K. Böhlke; P. De Bièvre; H. Hidaka; H. S. Peiser; K. J. R. Rosman; P. D. P. Taylor (2003). "Atomic weights of the elements. Review 2000 (IUPAC Technical Report)". Pure and Applied Chemistry. 75 (6): 683–800. doi:10.1351/pac200375060683.
  • M. E. Wieser (2006). "Atomic weights of the elements 2005 (IUPAC Technical Report)". Pure and Applied Chemistry. 78 (11): 2051–2066. doi:10.1351/pac200678112051. Lay summary.
• Half-life, spin, and isomer data selected from the following sources. See editing notes on this article's talk page.
  • G. Audi; A. H. Wapstra; C. Thibault; J. Blachot; O. Bersillon (2003). "The NUBASE evaluation of nuclear and decay properties" (PDF). Nuclear Physics A. 729: 3–128. Bibcode:2003NuPhA.729....3A. doi:10.1016/j.nuclphysa.2003.11.001.
  • National Nuclear Data Center. "NuDat 2.1 database". Brookhaven National Laboratory. Retrieved September 2005. Check date values in: |access-date= (help)
  • N. E. Holden (2004). "Table of the Isotopes". In D. R. Lide. CRC Handbook of Chemistry and Physics (85th ed.). CRC Press. Section 11. ISBN 978-0-8493-0485-9.