Isotopes of krypton
There are 33 known isotopes of krypton (Kr) with atomic mass numbers from 69 through 101.[1] Naturally occurring krypton is made of six stable isotopes, two of which might theoretically be slightly radioactive, plus traces of radioisotopes that are produced by cosmic rays in the atmosphere.
The spectral signature of krypton can be observed to have several very sharp lines. When krypton is placed into an electric discharge tube, it emits visible light with a distinctive orange-red color.
Radioactive krypton-81 is the product of reactions with cosmic rays that strike the atmosphere, along with some of the other isotopes of krypton. Krypton-81 has a half-life of about 229,000 years.
Krypton-81 has been used for dating old (50,000 to 800,000 year-old) groundwater.[2]
Krypton-85 is a radioisotope of krypton that has a half-life of about 10.75 years. This isotope is produced by the nuclear fission of uranium and plutonium in nuclear weapons testing and in nuclear reactors, as well as by cosmic rays. An important goal of the Limited Nuclear Test Ban Treaty of 1963 was to eliminate the release of such radioisotopes into the atmosphere, and since 1963 much of that krypton-85 has had time to decay. However, it is inevitable that krypton-85 is released during the reprocessing of fuel rods from nuclear reactors.
The atmospheric concentration of krypton-85 around the North Pole is about 30 percent higher than that at the Amundsen-Scott Station at the South Pole because nearly all of the world's nuclear reactors and all of its major nuclear reprocessing plants are located in the Northern Hemisphere, and also well-north of the equator.[3] To be more specific, those nuclear reprocessing plants with significant capacities are located in the United States, the United Kingdom, the French Republic, the Russian Federation, Mainland China (PRC), Japan, India, and Pakistan. See the article on nuclear reprocessing for more information.
All of the other radioisotopes of krypton have half-lives of less that one day, except for krypton-79, which has a half-life of about 35.0 hours. This isotope decays by the emission of positrons and thus becoming bromine.
Table
nuclide symbol |
Z(p) | N(n) | isotopic mass (u) |
half-life | decay mode(s)[4][n 1] |
daughter isotope(s)[n 2] |
nuclear spin |
representative isotopic composition (mole fraction) |
range of natural variation (mole fraction) |
---|---|---|---|---|---|---|---|---|---|
excitation energy | |||||||||
69Kr | 36 | 33 | 68.96518(43)# | 32(10) ms | β+ | 69Br | 5/2-# | ||
70Kr | 36 | 34 | 69.95526(41)# | 52(17) ms | β+ | 70Br | 0+ | ||
71Kr | 36 | 35 | 70.94963(70) | 100(3) ms | β+ (94.8%) | 71Br | (5/2)- | ||
β+, p (5.2%) | 70Se | ||||||||
72Kr | 36 | 36 | 71.942092(9) | 17.16(18) s | β+ | 72Br | 0+ | ||
73Kr | 36 | 37 | 72.939289(7) | 28.6(6) s | β+ (99.32%) | 73Br | 3/2- | ||
β+, p (.68%) | 72Se | ||||||||
73mKr | 433.66(12) keV | 107(10) ns | (9/2+) | ||||||
74Kr | 36 | 38 | 73.9330844(22) | 11.50(11) min | β+ | 74Br | 0+ | ||
75Kr | 36 | 39 | 74.930946(9) | 4.29(17) min | β+ | 75Br | 5/2+ | ||
76Kr | 36 | 40 | 75.925910(4) | 14.8(1) h | β+ | 76Br | 0+ | ||
77Kr | 36 | 41 | 76.9246700(21) | 74.4(6) min | β+ | 77Br | 5/2+ | ||
78Kr | 36 | 42 | 77.9203648(12) | Observationally Stable[n 3] | 0+ | 0.00355(3) | |||
79Kr | 36 | 43 | 78.920082(4) | 35.04(10) h | β+ | 79Br | 1/2- | ||
79mKr | 129.77(5) keV | 50(3) s | 7/2+ | ||||||
80Kr | 36 | 44 | 79.9163790(16) | Stable | 0+ | 0.02286(10) | |||
81Kr[n 4] | 36 | 45 | 80.9165920(21) | 2.29(11)×105 a | EC | 81Br | 7/2+ | ||
81mKr | 190.62(4) keV | 13.10(3) s | IT (99.975%) | 81Kr | 1/2- | ||||
EC (.025%) | 81Br | ||||||||
82Kr | 36 | 46 | 81.9134836(19) | Stable | 0+ | 0.11593(31) | |||
83Kr[n 5] | 36 | 47 | 82.914136(3) | Stable | 9/2+ | 0.11500(19) | |||
83m1Kr | 9.4053(8) keV | 154.4(11) ns | 7/2+ | ||||||
83m2Kr | 41.5569(10) keV | 1.83(2) h | IT | 83Kr | 1/2- | ||||
84Kr[n 5] | 36 | 48 | 83.911507(3) | Stable | 0+ | 0.56987(15) | |||
84mKr | 3236.02(18) keV | 1.89(4) µs | 8+ | ||||||
85Kr[n 5] | 36 | 49 | 84.9125273(21) | 10.776(3) a | β- | 85Rb | 9/2+ | ||
85m1Kr | 304.871(20) keV | 4.480(8) h | β- (78.6%) | 85Rb | 1/2- | ||||
IT (21.4%) | 85Kr | ||||||||
85m2Kr | 1991.8(13) keV | 1.6(7) µs [1.2(+10-4) µs] |
(17/2+) | ||||||
86Kr[n 5] | 36 | 50 | 85.91061073(11) | Observationally Stable[n 6] | 0+ | 0.17279(41) | |||
87Kr | 36 | 51 | 86.91335486(29) | 76.3(5) min | β- | 87Rb | 5/2+ | ||
88Kr | 36 | 52 | 87.914447(14) | 2.84(3) h | β- | 88Rb | 0+ | ||
89Kr | 36 | 53 | 88.91763(6) | 3.15(4) min | β- | 89Rb | 3/2(+#) | ||
90Kr | 36 | 54 | 89.919517(20) | 32.32(9) s | β- | 90mRb | 0+ | ||
91Kr | 36 | 55 | 90.92345(6) | 8.57(4) s | β- | 91Rb | 5/2(+) | ||
92Kr | 36 | 56 | 91.926156(13) | 1.840(8) s | β- (99.96%) | 92Rb | 0+ | ||
β-, n (.033%) | 91Rb | ||||||||
93Kr | 36 | 57 | 92.93127(11) | 1.286(10) s | β- (98.05%) | 93Rb | 1/2+ | ||
β-, n (1.95%) | 92Rb | ||||||||
94Kr | 36 | 58 | 93.93436(32)# | 210(4) ms | β- (94.3%) | 94Rb | 0+ | ||
β-, n (5.7%) | 93Rb | ||||||||
95Kr | 36 | 59 | 94.93984(43)# | 114(3) ms | β- | 95Rb | 1/2(+) | ||
96Kr | 36 | 60 | 95.94307(54)# | 80(7) ms | β- | 96Rb | 0+ | ||
97Kr | 36 | 61 | 96.94856(54)# | 63(4) ms | β- | 97Rb | 3/2+# | ||
β-, n | 96Rb | ||||||||
98Kr | 36 | 62 | 97.95191(64)# | 46(8) ms | 0+ | ||||
99Kr | 36 | 63 | 98.95760(64)# | 40(11) ms | (3/2+)# | ||||
100Kr | 36 | 64 | 99.96114(54)# | 10# ms [>300 ns] |
0+ | ||||
101Kr [n 7] | 36 | 65 | unknown | >635 ns | β- 2n, β- n, β- | (in order of decay mode) 99Rb, 100Rb, 101Rb | unknown |
- ^ 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)
- ^ Believed to decay by β+β+ to 78Se with a half-life of more than >1.1×1020 years
- ^ Used to date groundwater
- ^ a b c d Fission product
- ^ Believed to decay by β-β- to 86Sr
- ^ New isotope.
See also
The meter and krypton-86
meter#standard_wavelength_of_krypton-86_emission
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
- ^ Brookhaven National Laboratory: Meet krypton's newest isotope, 101Kr, discover info about krypton's newest isotope, 101Kr, discovered in late 2011.
- ^
N. Thonnard, L. D. MeKay, T. C. Labotka (2001). "Development of Laser-Based Resonance Ionization Techniques for 81-Kr and 85-Kr Measurements in the Geosciences" (PDF). University of Tennessee, Institute for Rare Isotope Measurements. pp. 4–7.
{{cite web}}
: CS1 maint: multiple names: authors list (link) - ^ "Resources on Isotopes". U.S. Geological Survey. Retrieved 2007-03-20.
- ^ http://www.nucleonica.net/unc.aspx
- Isotope masses from:
- G. Audi, A. H. Wapstra, C. Thibault, J. Blachot and 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.
{{cite journal}}
: CS1 maint: multiple names: authors list (link)
- G. Audi, A. H. Wapstra, C. Thibault, J. Blachot and 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.
- 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 and 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.
{{cite journal}}
: CS1 maint: multiple names: authors list (link) - 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.
{{cite journal}}
: Unknown parameter|laysummary=
ignored (help)
- J. R. de Laeter, J. K. Böhlke, P. De Bièvre, H. Hidaka, H. S. Peiser, K. J. R. Rosman and 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.
- 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 and 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.
{{cite journal}}
: CS1 maint: multiple names: authors list (link) - National Nuclear Data Center. "NuDat 2.1 database". Brookhaven National Laboratory. Retrieved September 2005.
{{cite web}}
: Check date values in:|accessdate=
(help) - N. E. Holden (2004). "Table of the Isotopes". In D. R. Lide (ed.). CRC Handbook of Chemistry and Physics (85th ed.). CRC Press. Section 11. ISBN 978-0-8493-0485-9.
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suggested) (help)
- G. Audi, A. H. Wapstra, C. Thibault, J. Blachot and 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.