Isotopes of krypton

Template:Infobox krypton isotopes 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 (The element Chemistry:krypton does not exist.) 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.[1]

## Contents

* 1 List of isotopes
* 2 Notable isotopes
* 2.1 Krypton-81
* 2.2 Krypton-85
* 2.2.1 Atmospheric concentration
* 2.3 Krypton-86
* 3 See also
* 4 References
* 5 External links

## List of isotopes

Nuclide
[n 1] | Z | N | Isotopic mass (u)
[n 2][n 3] | Half-life
[n 4][n 5] | Decay
mode
[n 6] | Daughter
isotope
[n 7][n 8] | Spin and
parity
[n 9][n 5] | Physics:Natural abundance (mole fraction)

|
|
|
|
|
|
|
|

Excitation energy  | Normal proportion  | 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[3] |
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[3] |
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)[4] | 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[5] | 36  | 66  |  |  |  |  | 0+  |  |
103Kr[6] | 36  | 67  |  |  |  |  |  |  |

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. ↑ 5.0 5.1 # - 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. ↑ 12.0 12.1 12.2 12.3 12.4 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

### Krypton-81

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.[7] 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, bridging the gap where other isotopic methods (e.g. carbon-14 dating) lose sensitivity. 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.[8] More recently, it has been announced[9] that samples an order of magnitude less can be used successfully.

The short-lived isomer krypton-81m (half-life 13 seconds) has medical uses but is often considered impractical for use as it must be generated from the rare rubidium-81.[10] It almost entirely decays to the ground state with a monochromatic gamma ray.

### Krypton-85

Main article: Physics: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,[11] which is far larger-volume than was ever nuclear testing.

#### Atmospheric concentration

See also: Physics: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[12] 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

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.[13]

## See also

Daughter products other than krypton

* Isotopes of rubidium
* Isotopes of bromine
* Isotopes of selenium

## References

1. ↑ Turkevich, Anthony; Winsberg, Lester; Flotow, Howard; Adams, Richard M. (1997). "The radioactivity of atmospheric krypton in 1949–1950". Proceedings of the National Academy of Sciences 94 (15): 7807–7810. doi:10.1073/pnas.94.15.7807. PMID 11607731. Bibcode: 1997PNAS...94.7807T.
2. ↑ Cite error: Invalid `<ref>` tag; no text was provided for refs named `Patrignani2016`
3. ↑ 3.0 3.1 Lu, Zheng-Tian (1 March 2013). "What trapped atoms reveal about global groundwater". Physics Today 66 (3): 74–75. doi:10.1063/PT.3.1926. Bibcode: 2013PhT....66c..74L. https://pubs.aip.org/physicstoday/article/66/3/74/414350/What-trapped-atoms-reveal-about-global. Retrieved 29 June 2024.
4. ↑ Smith, Matthew B.; Murböck, Tobias; Dunling, Eleanor; Jacobs, Andrew; Kootte, Brian; Lan, Yang; Leistenschneider, Erich; Lunney, David et al. (2020). "High-precision mass measurement of neutron-rich 96Kr". Hyperfine Interactions 241 (1): 59. doi:10.1007/s10751-020-01722-2. Bibcode: 2020HyInt.241...59S. https://link.springer.com/article/10.1007/s10751-020-01722-2.
5. ↑ Sumikama, T. et al. (2021). "Observation of new neutron-rich isotopes in the vicinity of Zr110". Physical Review C 103 (1). doi:10.1103/PhysRevC.103.014614. Bibcode: 2021PhRvC.103a4614S. https://journals.aps.org/prc/abstract/10.1103/PhysRevC.103.014614.
6. ↑ Shimizu, Y.; Kubo, T.; Sumikama, T.; Fukuda, N.; Takeda, H.; Suzuki, H.; Ahn, D. S.; Inabe, N. et al. (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). doi:10.1103/PhysRevC.109.044313.
7. ↑ 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". Antarctic Meteorite Research 17: 185–199. Bibcode: 2004AMR....17..185L. https://core.ac.uk/download/pdf/51485498.pdf.
8. ↑ Thonnard, N.; MeKay, L. D.; Labotka, T. C. (2001). ﻿Development of Laser-Based Resonance Ionization Techniques for 81-Kr and 85-Kr Measurements in the Geosciences﻿ (Report). University of Tennessee, Institute for Rare Isotope Measurements. pp. 4–7. doi:10.2172/809813. https://digital.library.unt.edu/ark:/67531/metadc737461/m2/1/high_res_d/809813.pdf.
9. ↑ 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". Analytical Chemistry 86 (8): 4002–4007. doi:10.1021/ac500415a. PMID 24641193. Bibcode: 2014AnaCh..86.4002T. http://staff.ustc.edu.cn/~smhu/publication/AC2014Tu.pdf.
10. ↑ Watson, I. A.; Waters, S. L. (1986). "Pharmaceutical Aspects of Krypton-81m Generators". in Cox, P. H.; Mather, S. J.; Sampson, C. B. et al. (in en). Progress in Radiopharmacy. Dordrecht: Springer Netherlands. pp. 32–45. doi:10.1007/978-94-009-4297-4_3. ISBN 978-94-010-8410-9. http://link.springer.com/10.1007/978-94-009-4297-4_3. Retrieved 2025-10-15.
11. ↑ "Separation, Storage and Disposal of Krypton-85". p. 8. https://inis.iaea.org/collection/NCLCollectionStore/_Public/11/569/11569296.pdf.
12. ↑ "Resources on Isotopes". U.S. Geological Survey. https://wwwrcamnl.wr.usgs.gov/isoig/period/kr_iig.html.
13. ↑ Baird, K. M.; Howlett, L. E. (1963). "The International Length Standard". Applied Optics 2 (5): 455–463. doi:10.1364/AO.2.000455. Bibcode: 1963ApOpt...2..455B.

## External links

* Brookhaven National Laboratory: Krypton-101 information

Lua error: Internal error: The interpreter has terminated with signal "24".

Lua error: Internal error: The interpreter has terminated with signal "24".

Retrieved from "https://handwiki.org/wiki/index.php?title=Physics:Isotopes_of_krypton&oldid=4334586"