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Isotopes of krypton

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Isotopes of krypton (36Kr)
Main isotopes[1] Decay
abun­dance half-life (t1/2) mode pro­duct
78Kr 0.360% 9.2×1021 y[2] εε 78Se
79Kr synth 1.46 d β+ 79Br
80Kr 2.29% stable
81Kr trace 2.3×105 y ε 81Br
81mKr synth 13.10 s IT 81Kr
ε 81Br
82Kr 11.6% stable
83Kr 11.5% stable
84Kr 57.0% stable
85Kr trace 10.728 y β− 85Rb
86Kr 17.3% stable
Standard atomic weight Ar°(Kr)

There are 34 known isotopes of krypton (36Kr) with atomic mass numbers from 67 to 103. Naturally occurring krypton is made of five stable isotopes and one (78
Kr) which is slightly radioactive with an extremely long half-life, plus traces of radioisotopes that are produced by cosmic rays in the atmosphere. Atmospheric krypton today is, however, considerably radioactive due almost entirely to artificial 85Kr.[5]

List of isotopes

[edit]
Nuclide
[n 1] 		Z N Isotopic mass (Da)[6]
[n 2][n 3] 		Half-life[1]
[n 4][n 5] 		Decay
mode[1]
[n 6] 		Daughter
isotope
[n 7][n 8] 		Spin and
parity[1]
[n 9][n 5] 		Natural abundance (mole fraction)
Excitation energy Normal proportion[1] Range of variation
67Kr 36 31 66.98331(46)# 7.4(29) ms β+? (63%) 67Br 3/2-#
2p (37%) 65Se
68Kr 36 32 67.97249(54)# 21.6(33) ms β+, p (>90%) 67Se 0+
β+? (<10%) 68Br
p? 67Br
69Kr 36 33 68.96550(32)# 27.9(8) ms β+, p (94%) 68Se (5/2−)
β+ (6%) 69Br
70Kr 36 34 69.95588(22)# 45.00(14) ms β+ (>98.7%) 70Br 0+
β+, p (<1.3%) 69Se
71Kr 36 35 70.95027(14) 98.8(3) ms β+ (97.9%) 71Br (5/2)−
β+, p (2.1%) 70Se
72Kr 36 36 71.9420924(86) 17.16(18) s β+ 72Br 0+
73Kr 36 37 72.9392892(71) 27.3(10) s β+ (99.75%) 73Br (3/2)−
β+, p (0.25%) 72Se
73mKr 433.55(13) keV 107(10) ns IT 73Kr (9/2+)
74Kr 36 38 73.9330840(22) 11.50(11) min β+ 74Br 0+
75Kr 36 39 74.9309457(87) 4.60(7) min β+ 75Br 5/2+
76Kr 36 40 75.9259107(43) 14.8(1) h β+ 76Br 0+
77Kr 36 41 76.9246700(21) 72.6(9) min β+ 77Br 5/2+
77mKr 66.50(5) keV 118(12) ns IT 77Kr 3/2−
78Kr[n 10] 36 42 77.92036634(33) 9.2 +5.5
−2.6 ±1.3×1021 y[2] 		Double EC 78Se 0+ 0.00355(3)
79Kr 36 43 78.9200829(37) 35.04(10) h β+ 79Br 1/2−
79mKr 129.77(5) keV 50(3) s IT 79Kr 7/2+
80Kr 36 44 79.91637794(75) Stable 0+ 0.02286(10)
81Kr[n 11] 36 45 80.9165897(12) 2.29(11)×105 y EC 81Br 7/2+ 6×10−13[7]
81mKr 190.64(4) keV 13.10(3) s IT 81Kr 1/2−
EC (0.0025%) 81Br
82Kr 36 46 81.9134811537(59) Stable 0+ 0.11593(31)
83Kr[n 12] 36 47 82.914126516(9) Stable 9/2+ 0.11500(19)
83m1Kr 9.4053(8) keV 156.8(5) ns IT 83Kr 7/2+
83m2Kr 41.5575(7) keV 1.830(13) h IT 83Kr 1/2−
84Kr[n 12] 36 48 83.9114977271(41) Stable 0+ 0.56987(15)
84mKr 3236.07(18) keV 1.83(4) μs IT 84Kr 8+
85Kr[n 12] 36 49 84.9125273(21) 10.728(7) y β− 85Rb 9/2+ 1×10−11[7]
85m1Kr[n 12] 304.871(20) keV 4.480(8) h β− (78.8%) 85Rb 1/2−
IT (21.2%) 85Kr
85m2Kr 1991.8(2) keV 1.82(5) μs
 IT 85Kr (17/2+)
86Kr[n 13][n 12] 36 50 85.9106106247(40) Observationally Stable[n 14] 0+ 0.17279(41)
87Kr 36 51 86.91335476(26) 76.3(5) min β− 87Rb 5/2+
88Kr 36 52 87.9144479(28) 2.825(19) h β− 88Rb 0+
89Kr 36 53 88.9178354(23) 3.15(4) min β− 89Rb 3/2+
90Kr 36 54 89.9195279(20) 32.32(9) s β− 90mRb 0+
91Kr 36 55 90.9238063(24) 8.57(4) s β− 91Rb 5/2+
β−, n? 90Rb
92Kr 36 56 91.9261731(29) 1.840(8) s β− (99.97%) 92Rb 0+
β−, n (0.0332%) 91Rb
93Kr 36 57 92.9311472(27) 1.287(10) s β− (98.05%) 93Rb 1/2+
β−, n (1.95%) 92Rb
94Kr 36 58 93.934140(13) 212(4) ms β− (98.89%) 94Rb 0+
β−, n (1.11%) 93Rb
95Kr 36 59 94.939711(20) 114(3) ms β− (97.13%) 95Rb 1/2+
β−, n (2.87%) 94Rb
β−, 2n? 93Rb
95mKr 195.5(3) keV 1.582(22) μs
 IT 95Kr (7/2+)
96Kr 36 60 95.942998(62)[8] 80(8) ms β− (96.3%) 96Rb 0+
β−, n (3.7%) 95Rb
97Kr 36 61 96.94909(14) 62.2(32) ms β− (93.3%) 97Rb 3/2+#
β−, n (6.7%) 96Rb
β−, 2n? 95Rb
98Kr 36 62 97.95264(32)# 42.8(36) ms β− (93.0%) 98Rb 0+
β−, n (7.0%) 97Rb
β−, 2n? 96Rb
99Kr 36 63 98.95878(43)# 40(11) ms β− (89%) 99Rb 5/2−#
β−, n (11%) 98Rb
β−, 2n? 97Rb
100Kr 36 64 99.96300(43)# 12(8) ms β− 100Rb 0+
β−, n? 99Rb
β−, 2n? 98Rb
101Kr 36 65 100.96932(54)# 9# ms
[>400 ns] 		β−? 101Rb 5/2+#
β−, n? 100Rb
β−, 2n? 99Rb
102Kr[9] 36 66 0+
103Kr[10] 36 67
This table header & footer:
  1. ^ mKr – 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. ^ a b # – Values marked # are not purely derived from experimental data, but at least partly from trends of neighboring nuclides (TNN).
  6. ^ Modes of decay:
    n: Neutron emission
  7. ^ Bold italics symbol as daughter – Daughter product is nearly stable.
  8. ^ Bold symbol as daughter – Daughter product is stable.
  9. ^ ( ) spin value – Indicates spin with weak assignment arguments.
  10. ^ Primordial radionuclide
  11. ^ Used to date groundwater
  12. ^ a b c d e Fission product
  13. ^ Formerly used to define the meter
  14. ^ Believed to decay by β−β− to 86Sr
  • The isotopic composition refers to that in air.

Notable isotopes

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Krypton-81

[edit]

Krypton-81 (half-life 230,000 years) is useful in determining how old the water beneath the ground is. Radioactive krypton-81 is the product of spallation reactions with cosmic rays striking gases present in the Earth atmosphere, along with the six stable or nearly stable krypton isotopes.[11] The long half-life ensures that the isotope has a uniform concentration in the atmosphere and in surface water; when the water goes underground is supply is no longer replenished and decays, allowing dating of the residence time in deep aquifers in a range of 20,000 to a million years. The same long half-life renders detection of its decay impossible and, therefore, demands some form of mass spectrometry; even so, technical limitations of the method have traditionally required the sampling of very large volumes of water: several hundred liters or a few cubic meters of water (about a milligram of krypton). This is particularly challenging for dating pore water in deep clay aquitards with very low hydraulic conductivity.[12]

More recently, it has been announced[13] that samples an order of magnitude less can be used successfully.

The short-lived isomer (13 sec.) krypton-81m has medical uses [2] but is often considered impracticable as it must be generated from the rare rubidium-81. It almost entirely decays to the ground state with a monochromatic gamma ray.

Krypton-85

[edit]
Main article: Krypton-85

Krypton-85 (half-life 10.728 years) 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 almost inevitable that krypton-85 is released during the reprocessing of fuel rods from nuclear reactors,[14] which is far larger-volume than was ever nuclear testing.

Atmospheric concentration

[edit]
See also: Nuclear reprocessing

The atmospheric concentration of krypton-85 around the North Pole is about 30 percent higher than that 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, well north of the equator[15] and transfer of air between the hemispheres is slow.

The 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.

Krypton-86

[edit]

Krypton-86 was formerly used to define the meter from 1960 until 1983, when the definition of the meter was based on the wavelength of the 606 nm (orange) spectral line of a krypton-86 atom.[16]

See also

[edit]

Daughter products other than krypton

References

[edit]
  1. ^ a b c d e Kondev, F. G.; Wang, M.; Huang, W. J.; Naimi, S.; Audi, G. (2021). "The NUBASE2020 evaluation of nuclear properties" (PDF). Chinese Physics C. 45 (3): 030001. doi:10.1088/1674-1137/abddae.
  2. ^ a b Patrignani, C.; et al. (Particle Data Group) (2016). "Review of Particle Physics". Chinese Physics C. 40 (10): 100001. Bibcode:2016ChPhC..40j0001P. doi:10.1088/1674-1137/40/10/100001. See p. 768
  3. ^ "Standard Atomic Weights: Krypton". CIAAW. 2001.
  4. ^ 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.
  5. ^ [1]
  6. ^ 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.
  7. ^ a b Lu, Zheng-Tian (1 March 2013). "What trapped atoms reveal about global groundwater". Physics Today. 66 (3): 74–75. Bibcode:2013PhT....66c..74L. doi:10.1063/PT.3.1926. Retrieved 29 June 2024.
  8. ^ Smith, Matthew B.; Murböck, Tobias; Dunling, Eleanor; Jacobs, Andrew; Kootte, Brian; Lan, Yang; Leistenschneider, Erich; Lunney, David; Lykiardopoulou, Eleni Marina; Mukul, Ish; Paul, Stefan F.; Reiter, Moritz P.; Will, Christian; Dilling, Jens; Kwiatkowski, Anna A. (2020). "High-precision mass measurement of neutron-rich 96Kr". Hyperfine Interactions. 241 (1): 59. Bibcode:2020HyInt.241...59S. doi:10.1007/s10751-020-01722-2. S2CID 220512482.
  9. ^ Sumikama, T.; et al. (2021). "Observation of new neutron-rich isotopes in the vicinity of Zr110". Physical Review C. 103 (1): 014614. Bibcode:2021PhRvC.103a4614S. doi:10.1103/PhysRevC.103.014614. hdl:10261/260248. S2CID 234019083.
  10. ^ Shimizu, Y.; Kubo, T.; Sumikama, T.; Fukuda, N.; Takeda, H.; Suzuki, H.; Ahn, D. S.; Inabe, N.; Kusaka, K.; Ohtake, M.; Yanagisawa, Y.; Yoshida, K.; Ichikawa, Y.; Isobe, T.; Otsu, H.; Sato, H.; Sonoda, T.; Murai, D.; Iwasa, N.; Imai, N.; Hirayama, Y.; Jeong, S. C.; Kimura, S.; Miyatake, H.; Mukai, M.; Kim, D. G.; Kim, E.; Yagi, A. (8 April 2024). "Production of new neutron-rich isotopes near the N = 60 isotones Ge 92 and As 93 by in-flight fission of a 345 MeV/nucleon U 238 beam". Physical Review C. 109 (4): 044313. doi:10.1103/PhysRevC.109.044313.
  11. ^ Leya, I.; Gilabert, E.; Lavielle, B.; Wiechert, U.; Wieler, W. (2004). "Production rates for cosmogenic krypton and argon isotopes in H-chondrites with known 36Cl-36Ar ages" (PDF). Antarctic Meteorite Research. 17: 185–199. Bibcode:2004AMR....17..185L.
  12. ^ 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) (Report). University of Tennessee, Institute for Rare Isotope Measurements. pp. 4–7. doi:10.2172/809813.
  13. ^ Le-Yi Tu, Guo-Min Yang, Cun-Feng Cheng, Gu-Liang Liu, Xiang-Yang Zhang, and Shui-Ming Hu (2014). "Analysis of Krypton-85 and Krypton-81 in a Few Liters of Air" (PDF). Analytical Chemistry. 86 (8): 4002–4007.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  14. ^ "Separation, Storage and Disposal of Krypton-85" (PDF). p. 8. Retrieved 2024-12-08.
  15. ^ "Resources on Isotopes". U.S. Geological Survey. Archived from the original on 2001-09-24. Retrieved 2007-03-20.
  16. ^ Baird, K. M.; Howlett, L. E. (1963). "The International Length Standard". Applied Optics. 2 (5): 455–463. Bibcode:1963ApOpt...2..455B. doi:10.1364/AO.2.000455.
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