Isotopes of europium
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Standard atomic weight (Ar) |
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Naturally occurring europium (63Eu) is composed of 2 isotopes, 151Eu and 153Eu, with 153Eu being the most abundant (52.2% natural abundance). While 153Eu is observationally stable, 151Eu was recently found to be unstable and to undergo alpha decay.[2] The half-life is measured to be (4.62 ± 0.95(stat.) ± 0.68(syst.)) × 1018 y[3] which corresponds to 1 alpha decay per two minutes in every kilogram of natural europium. Besides natural radioisotopes 151Eu and 153Eu, 36 artificial radioisotopes have been characterized, with the most stable being 150Eu with a half-life of 36.9 years, 152Eu with a half-life of 13.516 years, 154Eu with a half-life of 8.593 years, and 155Eu with a half-life of 4.7612 years. The majority of the remaining radioactive isotopes have half-lives that are less than 12.2 seconds. This element also has 17 meta states, with the most stable being 150mEu (t1/2 12.8 hours), 152m1Eu (t1/2 9.3116 hours) and 152m2Eu (t1/2 96 minutes).
The primary decay mode before the most abundant stable isotope, 153Eu, is electron capture, and the primary mode after is beta decay. The primary decay products before 153Eu are isotopes of samarium and the primary products after are isotopes of gadolinium.
Europium-155
Prop: Unit: |
t½ (a) |
Yield (%) |
Q * (keV) |
βγ * |
---|---|---|---|---|
155Eu | 4.76 | 0.0803 | 252 | βγ |
85Kr | 10.76 | 0.2180 | 687 | βγ |
113mCd | 14.1 | 0.0008 | 316 | β |
90Sr | 28.9 | 4.505 | 2826 | β |
137Cs | 30.23 | 6.337 | 1176 | βγ |
121mSn | 43.9 | 0.00005 | 390 | βγ |
151Sm | 96.6 | 0.5314 | 77 | β |
Europium-155 is a fission product with a half-life of 4.76 years. It has a maximum decay energy of 252 KeV. In a thermal reactor (almost all current nuclear power plants), it has a low fission product yield, about half of one percent as much as the most abundant fission products.
155Eu's large neutron capture cross section (about 3900 barns for thermal neutrons, 16000 resonance integral) means that most of even the small amount produced is destroyed in the course of the nuclear fuel's burnup. Yield, decay energy, and halflife are all far less than 137Cs and 90Sr, so 155Eu is not a significant contributor to nuclear waste.
Some 155Eu is also produced by successive neutron capture on 153Eu (nonradioactive, 350 barns thermal, 1500 resonance integral, yield is about 5 times as great as 155Eu) and 154Eu (half-life 8.6 years, 1400 barns thermal, 1600 resonance integral, fission yield is extremely small because beta decay stops at 154Sm); however the differing cross sections mean that both 155Eu and 154Eu are destroyed faster than they are produced.
154Eu is a prolific emitter of gamma radiation.[4]
Isotope | Halflife | Relative yield | Thermal neutron | Resonance integral |
---|---|---|---|---|
Eu-153 | Stable | 5 | 350 | 1500 |
Eu-154 | 8.6 years | Nearly 0 | 1500 | 1600 |
Eu-155 | 4.76 years | 1 | 3900 | 16000 |
List of isotopes
nuclide symbol |
Z(p) | N(n) | isotopic mass (u) |
half-life[n 1] | decay mode(s)[5][n 2] |
daughter isotope(s)[n 3] |
nuclear spin |
representative isotopic composition (mole fraction) |
range of natural variation (mole fraction) |
---|---|---|---|---|---|---|---|---|---|
excitation energy | |||||||||
130Eu | 63 | 67 | 129.96357(54)# | 1.1(5) ms [0.9(+5−3) ms] |
2+# | ||||
131Eu | 63 | 68 | 130.95775(43)# | 17.8(19) ms | 3/2+ | ||||
132Eu | 63 | 69 | 131.95437(43)# | 100# ms | β+ | 132Sm | |||
p | 131Sm | ||||||||
133Eu | 63 | 70 | 132.94924(32)# | 200# ms | β+ | 133Sm | 11/2−# | ||
134Eu | 63 | 71 | 133.94651(21)# | 0.5(2) s | β+ | 134Sm | |||
β+, p (rare) | 133Pm | ||||||||
135Eu | 63 | 72 | 134.94182(32)# | 1.5(2) s | β+ | 135Sm | 11/2−# | ||
β+, p | 134Pm | ||||||||
136Eu | 63 | 73 | 135.93960(21)# | 3.3(3) s | β+ (99.91%) | 136Sm | (7+) | ||
β+, p (.09%) | 135Pm | ||||||||
136mEu | 0(500)# keV | 3.8(3) s | β+ (99.91%) | 136Sm | (3+) | ||||
β+, p (.09%) | 135Pm | ||||||||
137Eu | 63 | 74 | 136.93557(21)# | 8.4(5) s | β+ | 137Sm | 11/2−# | ||
138Eu | 63 | 75 | 137.93371(3) | 12.1(6) s | β+ | 138Sm | (6−) | ||
139Eu | 63 | 76 | 138.929792(14) | 17.9(6) s | β+ | 139Sm | (11/2)− | ||
140Eu | 63 | 77 | 139.92809(6) | 1.51(2) s | β+ | 140Sm | 1+ | ||
140mEu | 210(15) keV | 125(2) ms | IT (99%) | 140Eu | 5−# | ||||
β+(1%) | 140Sm | ||||||||
141Eu | 63 | 78 | 140.924931(14) | 40.7(7) s | β+ | 141Sm | 5/2+ | ||
141mEu | 96.45(7) keV | 2.7(3) s | IT (86%) | 141Eu | 11/2− | ||||
β+ (14%) | 141Sm | ||||||||
142Eu | 63 | 79 | 141.92343(3) | 2.36(10) s | β+ | 142Sm | 1+ | ||
142mEu | 460(30) keV | 1.223(8) min | β+ | 142Sm | 8− | ||||
143Eu | 63 | 80 | 142.920298(12) | 2.59(2) min | β+ | 143Sm | 5/2+ | ||
143mEu | 389.51(4) keV | 50.0(5) µs | 11/2− | ||||||
144Eu | 63 | 81 | 143.918817(12) | 10.2(1) s | β+ | 144Sm | 1+ | ||
144mEu | 1127.6(6) keV | 1.0(1) µs | (8−) | ||||||
145Eu | 63 | 82 | 144.916265(4) | 5.93(4) d | β+ | 145Sm | 5/2+ | ||
145mEu | 716.0(3) keV | 490 ns | 11/2− | ||||||
146Eu | 63 | 83 | 145.917206(7) | 4.61(3) d | β+ | 146Sm | 4− | ||
146mEu | 666.37(16) keV | 235(3) µs | 9+ | ||||||
147Eu | 63 | 84 | 146.916746(3) | 24.1(6) d | β+ (99.99%) | 147Sm | 5/2+ | ||
α (.0022%) | 143Pm | ||||||||
148Eu | 63 | 85 | 147.918086(11) | 54.5(5) d | β+ (100%) | 148Sm | 5− | ||
α (9.39×10−7%) | 144Pm | ||||||||
149Eu | 63 | 86 | 148.917931(5) | 93.1(4) d | EC | 149Sm | 5/2+ | ||
150Eu | 63 | 87 | 149.919702(7) | 36.9(9) y | β+ | 150Sm | 5(−) | ||
150mEu | 42.1(5) keV | 12.8(1) h | β− (89%) | 150Gd | 0− | ||||
β+ (11%) | 150Sm | ||||||||
IT (5×10−8%) | 150Eu | ||||||||
151Eu[n 4] | 63 | 88 | 150.9198502(26) | 4.62×1018 y | α | 147Pm | 5/2+ | 0.4781(6) | |
151mEu | 196.245(10) keV | 58.9(5) µs | 11/2− | ||||||
152Eu | 63 | 89 | 151.9217445(26) | 13.537(6) y | EC (72.09%), β+ (0.027%) | 152Sm | 3− | ||
β− (27.9%) | 152Gd | ||||||||
152m1Eu | 45.5998(4) keV | 9.3116(13) h | β− (72%) | 152Gd | 0− | ||||
β+ (28%) | 152Sm | ||||||||
152m2Eu | 65.2969(4) keV | 0.94(8) µs | 1− | ||||||
152m3Eu | 78.2331(4) keV | 165(10) ns | 1+ | ||||||
152m4Eu | 89.8496(4) keV | 384(10) ns | 4+ | ||||||
152m5Eu | 147.86(10) keV | 96(1) min | 8− | ||||||
153Eu[n 5] | 63 | 90 | 152.9212303(26) | Observationally Stable[n 6] | 5/2+ | 0.5219(6) | |||
154Eu[n 5] | 63 | 91 | 153.9229792(26) | 8.593(4) y | β− (99.98%) | 154Gd | 3− | ||
EC (.02%) | 154Sm | ||||||||
154m1Eu | 145.3(3) keV | 46.3(4) min | IT | 154Eu | (8−) | ||||
154m2Eu | 68.1702(4) keV | 2.2(1) µs | 2+ | ||||||
155Eu[n 5] | 63 | 92 | 154.9228933(27) | 4.7611(13) y | β− | 155Gd | 5/2+ | ||
156Eu[n 5] | 63 | 93 | 155.924752(6) | 15.19(8) d | β− | 156Gd | 0+ | ||
157Eu | 63 | 94 | 156.925424(6) | 15.18(3) h | β− | 157Gd | 5/2+ | ||
158Eu | 63 | 95 | 157.92785(8) | 45.9(2) min | β− | 158Gd | (1−) | ||
159Eu | 63 | 96 | 158.929089(8) | 18.1(1) min | β− | 159Gd | 5/2+ | ||
160Eu | 63 | 97 | 159.93197(22)# | 38(4) s | β− | 160Gd | 1(−) | ||
161Eu | 63 | 98 | 160.93368(32)# | 26(3) s | β− | 161Gd | 5/2+# | ||
162Eu | 63 | 99 | 161.93704(32)# | 10.6(10) s | β− | 162Gd | |||
163Eu | 63 | 100 | 162.93921(54)# | 6# s | β− | 163Gd | 5/2+# | ||
164Eu | 63 | 101 | 163.94299(64)# | 2# s | β− | 164Gd | |||
165Eu | 63 | 102 | 164.94572(75)# | 1# s | β− | 165Gd | 5/2+# | ||
166Eu | 63 | 103 | 165.94997(86)# | 400# ms | β− | 166Gd | |||
167Eu | 63 | 104 | 166.95321(86)# | 200# ms | β− | 167Gd | 5/2+# |
- ↑ Bold for isotopes with half-lives longer than the age of the universe (nearly stable)
- ↑ Abbreviations:
EC: Electron capture
IT: Isomeric transition - ↑ Bold for stable isotopes, bold italics for nearly-stable isotopes (half-life longer than the age of the universe)
- ↑ primordial radionuclide
- 1 2 3 4 Fission product
- ↑ Believed to undergo α decay to 149Pm
Notes
- 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.
- 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
- ↑ Meija, J.; et al. (2016). "Atomic weights of the elements 2013 (IUPAC Technical Report)". Pure Appl. Chem. 88 (3): 265–91. doi:10.1515/pac-2015-0305.
- ↑ Belli, P.; et al. (2007). "Search for α decay of natural europium". Nuclear Physics A. 789: 15–29. Bibcode:2007NuPhA.789...15B. doi:10.1016/j.nuclphysa.2007.03.001.
- ↑ N. Casali; S. S. Nagorny; F. Orio; L. Pattavina; et al. (2014). "Discovery of the 151Eu α decay". Journal of Physics G: Nuclear and Particle Physics. 41 (7): 075101. doi:10.1088/0954-3899/41/7/075101.
- ↑ http://www-nds.ipen.br/sgnucdat/b2.pdf%5B%5D
- ↑ "Universal Nuclide Chart". nucleonica. (Registration required (help)).
- Isotope masses from:
- 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. Archived from the original (PDF) on 2008-09-23.
- 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. Archived from the original (PDF) on 2008-09-23.
- 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.
Isotopes of samarium | Isotopes of europium | Isotopes of gadolinium |
Table of nuclides |