Isotopes of selenium
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The chemical element selenium (34Se) has six naturally occurring isotopes, five of which are stable: 74Se, 76Se, 77Se, 78Se, and 80Se. The last three also occur as fission products, along with 79Se, which has a half-life of 327,000 years,[2][3] and 82Se, which has a very long half-life (~1020 years, decaying via double beta decay to 82Kr) and for practical purposes can be considered to be stable. There are 23 other unstable isotopes that have been characterized, the longest-lived being 79Se with a half-life 327,000 years, 75Se with a half-life of 120 days, and 72Se with a half-life of 8.40 days. Of the other isotopes, 73Se has the longest half-life, 7.15 hours; most others have half-lives not exceeding 38 seconds.
List of isotopes
nuclide symbol |
Z(p) | N(n) | isotopic mass (u) |
half-life[n 1] | decay mode(s)[4][n 2] |
daughter isotope(s)[n 3] |
nuclear spin |
representative isotopic composition (mole fraction) |
range of natural variation (mole fraction) |
---|---|---|---|---|---|---|---|---|---|
excitation energy | |||||||||
65Se | 34 | 31 | 64.96466(64)# | <50 ms | β+ (>99.9%) | 65As | 3/2−# | ||
β+, p (<.1%) | 64Ge | ||||||||
66Se | 34 | 32 | 65.95521(32)# | 33(12) ms | β+ | 66As | 0+ | ||
67Se | 34 | 33 | 66.95009(21)# | 133(11) ms | β+ (99.5%) | 67As | 5/2−# | ||
β+, p (.5%) | 66Ge | ||||||||
68Se | 34 | 34 | 67.94180(4) | 35.5(7) s | β+ | 68As | 0+ | ||
69Se | 34 | 35 | 68.93956(4) | 27.4(2) s | β+ (99.955%) | 69As | (1/2−) | ||
β+, p (.045%) | 68Ge | ||||||||
69m1Se | 39.4(1) keV | 2.0(2) µs | 5/2− | ||||||
69m2Se | 573.9(10) keV | 955(16) ns | 9/2+ | ||||||
70Se | 34 | 36 | 69.93339(7) | 41.1(3) min | β+ | 70As | 0+ | ||
71Se | 34 | 37 | 70.93224(3) | 4.74(5) min | β+ | 71As | 5/2− | ||
71m1Se | 48.79(5) keV | 5.6(7) µs | 1/2− to 9/2− | ||||||
71m2Se | 260.48(10) keV | 19.0(5) µs | (9/2)+ | ||||||
72Se | 34 | 38 | 71.927112(13) | 8.40(8) d | EC | 72As | 0+ | ||
73Se | 34 | 39 | 72.926765(11) | 7.15(8) h | β+ | 73As | 9/2+ | ||
73mSe | 25.71(4) keV | 39.8(13) min | IT | 73Se | 3/2− | ||||
β+ | 73As | ||||||||
74Se | 34 | 40 | 73.9224764(18) | Observationally Stable [n 4] | 0+ | 0.0089(4) | |||
75Se | 34 | 41 | 74.9225234(18) | 119.779(4) d | EC | 75As | 5/2+ | ||
76Se | 34 | 42 | 75.9192136(18) | Stable | 0+ | 0.0937(29) | |||
77Se | 34 | 43 | 76.9199140(18) | Stable | 1/2− | 0.0763(16) | |||
77mSe | 161.9223(7) keV | 17.36(5) s | IT | 77Se | 7/2+ | ||||
78Se | 34 | 44 | 77.9173091(18) | Stable | 0+ | 0.2377(28) | |||
79Se[n 5] | 34 | 45 | 78.9184991(18) | 3.27(8)×105 y | β− | 79Br | 7/2+ | ||
79mSe | 95.77(3) keV | 3.92(1) min | IT (99.944%) | 79Se | 1/2− | ||||
β− (.056%) | 79Br | ||||||||
80Se | 34 | 46 | 79.9165213(21) | Observationally Stable[n 6] | 0+ | 0.4961(41) | |||
81Se | 34 | 47 | 80.9179925(22) | 18.45(12) min | β− | 81Br | 1/2− | ||
81mSe | 102.99(6) keV | 57.28(2) min | IT (99.948%) | 81Se | 7/2+ | ||||
β− (.052%) | 81Br | ||||||||
82Se[n 7] | 34 | 48 | 81.9166994(22) | 0.97(5)×1020 y | β−β− | 82Kr | 0+ | 0.0873(22) | |
83Se | 34 | 49 | 82.919118(4) | 22.3(3) min | β− | 83Br | 9/2+ | ||
83mSe | 228.50(20) keV | 70.1(4) s | β− | 83Br | 1/2− | ||||
84Se | 34 | 50 | 83.918462(16) | 3.1(1) min | β− | 84Br | 0+ | ||
85Se | 34 | 51 | 84.92225(3) | 31.7(9) s | β− | 85Br | (5/2+)# | ||
86Se | 34 | 52 | 85.924272(17) | 15.3(9) s | β− | 86Br | 0+ | ||
87Se | 34 | 53 | 86.92852(4) | 5.50(12) s | β− (99.64%) | 87Br | (5/2+)# | ||
β−, n (.36%) | 86Br | ||||||||
88Se | 34 | 54 | 87.93142(5) | 1.53(6) s | β− (99.01%) | 88Br | 0+ | ||
β−, n (.99%) | 88Br | ||||||||
89Se | 34 | 55 | 88.93645(32)# | 0.41(4) s | β− (92.2%) | 89Br | (5/2+)# | ||
β−, n (7.8%) | 88Br | ||||||||
90Se | 34 | 56 | 89.93996(43)# | 300# ms [>300 ns] | β−, n | 89Br | 0+ | ||
β− | 90Br | ||||||||
91Se | 34 | 57 | 90.94596(54)# | 270(50) ms | β− (79%) | 91Br | 1/2+# | ||
β−, n | 90Br | ||||||||
92Se | 34 | 58 | 91.94992(64)# | 100# ms [>300 ns] | β− | 92Br | 0+ | ||
93Se | 34 | 59 | 92.95629(86)# | 50# ms [>300 ns] | 1/2+# | ||||
94Se | 34 | 60 | 93.96049(86)# | 20# ms [>300 ns] | 0+ |
- ↑ 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
- ↑ Believed to decay by β+β+ to 74Ge
- ↑ Long-lived fission product
- ↑ Believed to decay by β−β− to 80Kr
- ↑ Primordial radionuclide
Notes
- The precision of the isotope abundances and atomic mass is limited through variations. The given ranges should be applicable to any normal terrestrial material.
- 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.
See also
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.
- ↑ The half-life of 79Se Archived September 27, 2011, at the Wayback Machine.
- ↑ Jorg, Gerhard; Buhnemann, Rolf; Hollas, Simon; Kivel, Niko; Kossert, Karsten; Van Winckel, Stefaan; Gostomski, Christoph Lierse v. (2010). "Preparation of radiochemically pure 79Se and highly precise determination of its half-life". Applied Radiation and Isotopes. 68 (12): 2339–51. PMID 20627600. doi:10.1016/j.apradiso.2010.05.006.
- ↑ "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.
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