Isotopes of xenon

Naturally occurring xenon (₅₄Xe) consists of seven stable isotopes and two very long-lived isotopes. Double electron capture has been observed in ¹²⁴Xe (half-life 1.8 ± 0.5(stat) ± 0.1(sys) ×10²² years)^[2] and double beta decay in ¹³⁶Xe (half-life 2.165 ± 0.016(stat) ± 0.059(sys) ×10²¹ years),^[7] which are among the longest measured half-lives of all nuclides. The isotopes ¹²⁶Xe and ¹³⁴Xe are also predicted to undergo double beta decay,^[8] but this process has never been observed in these isotopes, so they are considered to be stable.^[9][10][11] Beyond these stable forms, 32 artificial unstable isotopes and various isomers have been studied, the longest-lived of which is ¹²⁷Xe with a half-life of 36.345 days. All other isotopes have half-lives less than 12 days, most less than 20 hours. The shortest-lived isotope, ¹⁰⁸Xe,^[12] has a half-life of 58 μs, and is the heaviest known nuclide with equal numbers of protons and neutrons. 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, so are used as indicators of nuclear explosions.

Isotopes of xenon (₅₄Xe)

Main isotopes[1] Decay abun­dance half-life (t1/2) mode pro­duct 124Xe 0.095% 1.8×1022 y[2] εε 124Te 125Xe synth 16.9 h β+ 125I 126Xe 0.0890% stable 127Xe synth 36.345 d ε 127I 128Xe 1.91% stable 129Xe 26.4% stable 130Xe 4.07% stable 131Xe 21.2% stable 132Xe 26.9% stable 133Xe synth 5.247 d β− 133Cs 134Xe 10.4% stable 135Xe synth 9.14 h β− 135Cs 136Xe 8.86% 2.165×1021 y[3][4] β−β− 136Ba
Standard atomic weight Ar°(Xe)
	131.293±0.006[5] 131.29±0.01 (abridged)[6]
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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. Because of this effect, designers must make provisions to increase the reactor's reactivity (the number of neutrons per fission that go on to fission other atoms of nuclear fuel) over the initial value needed to start the chain reaction. For the same reason, the fission products produced in a nuclear explosion and a power plant differ significantly as a large share of ¹³⁵
Xe will absorb neutrons in a steady state reactor, while basically none of the ¹³⁵
I will have had time to decay to xenon before the explosion of the bomb removes it from the neutron radiation.

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.^{[citation needed]} 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.^[13] It has been suggested that the isotopic composition of atmospheric xenon fluctuated prior to the GOE before stabilizing, perhaps as a result of the rise in atmospheric O₂.^[14]

List of isotopes

Nuclide [n 1]	Z	N	Isotopic mass (Da)[15] [n 2][n 3]	Half-life[1] [n 4]	Decay mode[1] [n 5]	Daughter isotope [n 6]	Spin and parity[1] [n 7][n 8]	Natural abundance (mole fraction)
	Excitation energy							Normal proportion[1]	Range of variation
108Xe[n 9]	54	54	107.95423(41)	72(35) μs	α	104Te	0+
109Xe	54	55	108.95043(32)	13(2) ms	α	105Te	(7/2+)
110Xe	54	56	109.94426(11)	93(3) ms	α (64%)	106Te	0+
					β+ (36%)	110I
111Xe	54	57	110.94147(12)#	740(200) ms	β+ (89.6%)	111I	5/2+#
					α (10.4%)	107Te
112Xe	54	58	111.9355591(89)	2.7(8) s	β+ (98.8%)	112I	0+
					α (1.2%)	108Te
113Xe	54	59	112.9332217(73)	2.74(8) s	β+ (92.98%)	113I	5/2+#
					β+, p (7%)	112Te
					α (?%)	109Te
					β+, α (~0.007%)	109Sb
113mXe	403.6(14) keV			6.9(3) μs	IT	113Xe	(11/2−)
114Xe	54	60	113.927980(12)	10.0(4) s	β+	114I	0+
115Xe	54	61	114.926294(13)	18(3) s	β+ (99.66%)	115I	(5/2+)
					β+, p (0.34%)	114Te
116Xe	54	62	115.921581(14)	59(2) s	β+	116I	0+
117Xe	54	63	116.920359(11)	61(2) s	β+	117I	5/2+
					β+, p (0.0029%)	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+ (79%)	119I	5/2+
					EC (21%)	119I
120Xe	54	66	119.911784(13)	46.0(6) min	β+	120I	0+
121Xe	54	67	120.911453(11)	40.1(20) min	β+	121I	5/2+
122Xe	54	68	121.908368(12)	20.1(1) h	EC	122I	0+
123Xe	54	69	122.908482(10)	2.08(2) h	β+	123I	1/2+
123mXe	185.18(11) keV			5.49(26) μs	IT	123Xe	7/2−
124Xe[n 10]	54	70	123.9058852(15)	1.8(5 (stat), 1 (sys))×1022 y[2]	Double EC	124Te	0+	9.5(5)×10−4
125Xe	54	71	124.9063876(15)	16.87(8) h	β+	125I	1/2+
125m1Xe	252.61(14) keV			56.9(9) s	IT	125Xe	9/2−
125m2Xe	295.89(15) keV			0.14(3) μs	IT	125Xe	7/2+
126Xe	54	72	125.904297422(6)	Observationally Stable[n 11]			0+	8.9(3)×10−4
127Xe	54	73	126.9051836(44)	36.342(3) d	EC	127I	1/2+
127mXe	297.10(8) keV			69.2(9) s	IT	127Xe	9/2−
128Xe	54	74	127.9035307534(56)	Stable			0+	0.01910(13)
128mXe	2787.2(3) keV			83(2) ns	IT	128Xe	8−
129Xe[n 12]	54	75	128.9047808574(54)	Stable			1/2+	0.26401(138)
129mXe	236.14(3) keV			8.88(2) d	IT	129Xe	11/2−
130Xe	54	76	129.903509346(10)	Stable			0+	0.04071(22)
131Xe[n 13]	54	77	130.9050841281(55)	Stable			3/2+	0.21232(51)
131mXe	163.930(8) keV			11.948(12) d	IT	131Xe	11/2−
132Xe[n 13]	54	78	131.9041550835(54)	Stable			0+	0.26909(55)
132mXe	2752.21(17) keV			8.39(11) ms	IT	132Xe	(10+)
133Xe[n 13][n 14]	54	79	132.9059107(26)	5.2474(5) d	β−	133Cs	3/2+
133m1Xe	233.221(15) keV			2.198(13) d	IT	133Xe	11/2−
133m2Xe	2147(20)# keV			8.64(13) ms	IT	133Xe	(23/2+)
134Xe[n 13]	54	80	133.905393030(6)	Observationally Stable[n 15]			0+	0.10436(35)
134m1Xe	1965.5(5) keV			290(17) ms	IT	134Xe	7−
134m2Xe	3025.2(15) keV			5(1) μs	IT	134Xe	(10+)
135Xe[n 16]	54	81	134.9072314(39)	9.14(2) h	β−	135Cs	3/2+
135mXe	526.551(13) keV			15.29(5) min	IT (99.70%)	135Xe	11/2−
					β− (0.30%)	135Cs
136Xe[n 10]	54	82	135 907214.474(7)	2.18(5)×1021 y	β−β−	136Ba	0+	0.08857(72)
136mXe	1891.74(7) keV			2.92(3) μs	IT	136Xe	6+
137Xe	54	83	136.91155777(11)	3.818(13) min	β−	137Cs	7/2−
138Xe	54	84	137.9141463(30)	14.14(7) min	β−	138Cs	0+
139Xe	54	85	138.9187922(23)	39.68(14) s	β−	139Cs	3/2−
140Xe	54	86	139.9216458(25)	13.60(10) s	β−	140Cs	0+
141Xe	54	87	140.9267872(31)	1.73(1) s	β− (99.96%)	141Cs	5/2−
					β−, n (0.044%)	140Cs
142Xe	54	88	141.9299731(29)	1.23(2) s	β− (99.63%)	142Cs	0+
					β−, n (0.37%)	141Cs
143Xe	54	89	142.9353696(50)	511(6) ms	β− (99.00%)	143Cs	5/2−
					β−, n (1.00%)	142Cs
144Xe	54	90	143.9389451(57)	0.388(7) s	β− (97.0%)	144Cs	0+
					β−, n (3.0%)	143Cs
145Xe	54	91	144.944720(12)	188(4) ms	β− (95.0%)	145Cs	3/2−#
					β−, n (5.0%)	144Cs
146Xe	54	92	145.948518(26)	146(6) ms	β−	146Cs	0+
					β−, n (6.9%)	145Cs
147Xe	54	93	146.95448(22)#	88(14) ms	β− (>92%)	147Cs	3/2−#
					β−, n (<8%)	146Cs
148Xe	54	94	147.95851(32)#	85(15) ms	β−	148Cs	0+
149Xe	54	95	148.96457(32)#	50# ms [>550 ms]			3/2−#
150Xe	54	96	149.96888(32)#	40# ms [>550 ns]]			0+
This table header & footer: view

1. ^mXe – Excited nuclear isomer.
2. ( ) – Uncertainty (1σ) is given in concise form in parentheses after the corresponding last digits.
3. # – Atomic mass marked #: value and uncertainty derived not from purely experimental data, but at least partly from trends from the Mass Surface (TMS).
4. Bold half-life – nearly stable, half-life longer than age of universe.
5. Modes of decay:

   EC:	Electron capture
   IT:	Isomeric transition
   n:	Neutron emission

6. Bold symbol as daughter – Daughter product is stable.
7. ( ) spin value – Indicates spin with weak assignment arguments.
8. # – Values marked # are not purely derived from experimental data, but at least partly from trends of neighboring nuclides (TNN).
9. Heaviest known isotope with equal numbers of protons and neutrons
10. Primordial radionuclide
11. Suspected of undergoing β⁺β⁺ decay to ¹²⁶Te
12. Used in a method of radiodating groundwater and to infer certain events in the Solar System's history
13. Fission product
14. Has medical uses
15. Theoretically capable of undergoing β⁻β⁻ decay to ¹³⁴Ba with a half-life over 2.8×10²² years^[11]
16. 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

• The isotopic composition refers to that in air.

Xenon-124

Xenon-124 is an isotope of xenon that undergoes double electron capture to tellurium-124 with a very long half-life of 1.8×10²² years, more than 12 orders of magnitude longer than the age of the universe ((13.799±0.021)×10⁹ years). Such decays have been observed in the XENON1T detector in 2019, and are the rarest processes ever directly observed.^[16] (Even slower decays of other nuclei have been measured, but by detecting decay products that have accumulated over billions of years rather than observing them directly.^[17])

Xenon-133

xenon-133, ¹³³Xe

General
Symbol	133Xe
Names	xenon-133, 133Xe, Xe-133
Protons (Z)	54
Neutrons (N)	79
Nuclide data
Natural abundance	syn
Half-life (t1/2)	5.243(1) d
Isotope mass	132.9059107 Da
Spin	3/2+
Decay products	133Cs
Decay modes
Decay mode	Decay energy (MeV)
Beta−	0.427
Isotopes of xenon Complete table of nuclides

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.^[18] It is also used to image blood flow, particularly in the brain.^{[19] 133}Xe is also an important fission product.^{[citation needed]} It is discharged to the atmosphere in small quantities by some nuclear power plants.^[20]

Xenon-135

Main article: 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^[21]). 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). It is discharged to the atmosphere in small quantities by some nuclear power plants.^[20]

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 10 orders of magnitude longer than the age of the universe ((13.799±0.021)×10⁹ years). It is being used in the Enriched Xenon Observatory experiment to search for neutrinoless double beta decay.

See also

• Xenon isotope geochemistry

References

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2. "Observation of two-neutrino double electron capture in ¹²⁴Xe with XENON1T". Nature. 568 (7753): 532–535. 2019. doi:10.1038/s41586-019-1124-4.
3. 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. arXiv:1306.6106. Bibcode:2014PhRvC..89a5502A. doi:10.1103/PhysRevC.89.015502.
4. Redshaw, M.; Wingfield, E.; McDaniel, J.; Myers, E. (2007). "Mass and Double-Beta-Decay Q Value of ¹³⁶Xe". Physical Review Letters. 98 (5): 53003. Bibcode:2007PhRvL..98e3003R. doi:10.1103/PhysRevLett.98.053003.
5. "Standard Atomic Weights: Xenon". CIAAW. 1999.
6. Prohaska, Thomas; Irrgeher, Johanna; Benefield, Jacqueline; Böhlke, John K.; Chesson, Lesley A.; Coplen, Tyler B.; Ding, Tiping; Dunn, Philip J. H.; Gröning, Manfred; Holden, Norman E.; Meijer, Harro A. J. (2022-05-04). "Standard atomic weights of the elements 2021 (IUPAC Technical Report)". Pure and Applied Chemistry. doi:10.1515/pac-2019-0603. ISSN 1365-3075.
7. 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 (1): 015502. arXiv:1306.6106. Bibcode:2014PhRvC..89a5502A. doi:10.1103/PhysRevC.89.015502. Archived from the original on 2023-06-13. Retrieved 2023-01-24.
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9. Status of ββ-decay in Xenon, Roland Lüscher, accessed online September 17, 2007. Archived September 27, 2007, at the Wayback Machine
10. Barros, N.; Thurn, J.; Zuber, K. (2014). "Double beta decay searches of ¹³⁴Xe, ¹²⁶Xe, and ¹²⁴Xe with large scale Xe detectors". Journal of Physics G. 41 (11): 115105–1–115105–12. arXiv:1409.8308. Bibcode:2014JPhG...41k5105B. doi:10.1088/0954-3899/41/11/115105. S2CID 116264328.
11. Yan, X.; Cheng, Z.; Abdukerim, A.; et al. (2024). "Searching for two-neutrino and neutrinoless double beta decay of ¹³⁴Xe with the PandaX-4T experiment". Physical Review Letters. 132 (152502). arXiv:2312.15632. doi:10.1103/PhysRevLett.132.152502.
12. Auranen, K.; et al. (2018). "Superallowed α decay to doubly magic ¹⁰⁰Sn" (PDF). Physical Review Letters. 121 (18): 182501. Bibcode:2018PhRvL.121r2501A. doi:10.1103/PhysRevLett.121.182501. PMID 30444390.
13. 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. S2CID 28159702.
14. Ardoin, L.; Broadley, M.W.; Almayrac, M.; Avice, G.; Byrne, D.J.; Tarantola, A.; Lepland, A.; Saito, T.; Komiya, T.; Shibuya, T.; Marty, B. (2022). "The end of the isotopic evolution of atmospheric xenon". Geochemical Perspectives Letters. 20: 43–47. Bibcode:2022GChPL..20...43A. doi:10.7185/geochemlet.2207. S2CID 247399987.
15. Wang, Meng; Huang, W.J.; Kondev, F.G.; Audi, G.; Naimi, S. (2021). "The AME 2020 atomic mass evaluation (II). Tables, graphs and references*". Chinese Physics C. 45 (3): 030003. doi:10.1088/1674-1137/abddaf.
16. David Nield (26 Apr 2019). "A Dark Matter Detector Just Recorded One of The Rarest Events Known to Science".
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18. 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.
19. 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.
20. Effluent Releases from Nuclear Power Plants and Fuel-Cycle Facilities. National Academies Press (US). 2012-03-29.
21. Chart of the Nuclides 13th Edition

• Isotope masses from Ame2003 Atomic Mass Evaluation by Georges Audi, Aaldert Hendrik Wapstra, Catherine Thibault, Jean Blachot and Olivier Bersillon in Nuclear Physics A729 (2003).
• Isotopic compositions and standard atomic masses from:
  • de Laeter, John Robert; Böhlke, John Karl; De Bièvre, Paul; Hidaka, Hiroshi; Peiser, H. Steffen; Rosman, Kevin J. R.; Taylor, Philip D. P. (2003). "Atomic weights of the elements. Review 2000 (IUPAC Technical Report)". Pure and Applied Chemistry. 75 (6): 683–800. doi:10.1351/pac200375060683.
  • Wieser, Michael E. (2006). "Atomic weights of the elements 2005 (IUPAC Technical Report)". Pure and Applied Chemistry. 78 (11): 2051–2066. doi:10.1351/pac200678112051.
• "News & Notices: Standard Atomic Weights Revised". International Union of Pure and Applied Chemistry. 19 October 2005.
• Half-life, spin, and isomer data selected from the following sources.
  • Audi, Georges; Bersillon, Olivier; Blachot, Jean; Wapstra, Aaldert Hendrik (2003), "The NUBASE evaluation of nuclear and decay properties", Nuclear Physics A, 729: 3–128, Bibcode:2003NuPhA.729....3A, doi:10.1016/j.nuclphysa.2003.11.001
  • National Nuclear Data Center. "NuDat 2.x database". Brookhaven National Laboratory.
  • Holden, Norman E. (2004). "11. Table of the Isotopes". In Lide, David R. (ed.). CRC Handbook of Chemistry and Physics (85th ed.). Boca Raton, Florida: CRC Press. ISBN 978-0-8493-0485-9.