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Isotopes of xenon

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Naturally occurring xenon (Xe) is made of eight stable isotopes. (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 2.11 x 1021yr[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 naturally occurring radioactive noble gases such as 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 which 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]
Standard atomic mass: 131.293(6) u

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, 133Xe
General
Symbol133Xe
Namesisotopes of xenon, 133Xe, Xe-133
Protons (Z)54
Neutrons (N)79
Nuclide data
Natural abundancesyn
Half-life (t1/2)5.243 d (1)
Isotope mass132.9059107 Da
Spin3/2
Decay products133Cs
Decay modes
Decay modeDecay energy (MeV)
Beta−0.427
Isotopes of xenon
Complete table of nuclides

Xenon-133 (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. It is also often used to image blood flow, particularly in the brain. 133Xe is also an important fission product.

Xenon-135

Main article: Xenon-135

Please visit the article Xenon-135 for information on this synthetic isotope. Go to Table of nuclides for a bonus external link.

Table

nuclide
symbol 		Z(p) N(n)  
isotopic mass (u)
  		half-life decay
mode(s)[6][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) Observationally Stable[n 5] 0 0.019102(8)
129Xe[n 6] 54 75 128.9047794(8) Observationally 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) Observationally Stable[n 5] 0 0.040710(13)
131Xe[n 7] 54 77 130.9050824(10) Observationally 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) Observationally Stable[n 5] 0 0.269086(33)
132mXe 2752.27(17) keV 8.39(11) ms IT 132Xe (10 )
133Xe[n 8][n 7] 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 54 82 135.907219(8) 2.11(0.04,0.21) x 1021yr[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. ^ a b c d e 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. ^ a b c d 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

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

  1. ^ Status of ββ-decay in Xenon, Roland Lüscher, accessed on line September 17, 2007.
  2. ^ Average (Recommended) Half-Life Values for Two-Neutrino Double-Beta Decay, A. S. Barabash, Czechoslovak Journal of Physics 52, #4 (April 2002), pp. 567–573.
  3. ^ Rajam, J. B. (1960). Atomic Physics (7th ed.). Delhi: S. Chand and Co. ISBN 812191809X.
  4. ^ a b Ackerman, N. (2011). "Observation of Two-Neutrino Double-Beta Decay in ^{136}Xe with the EXO-200 Detector". Physical Review Letters. 107 (21). doi:10.1103/PhysRevLett.107.212501.
  5. ^ Boulos, M.S. (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. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)
  6. ^ http://www.nucleonica.net/unc.aspx
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