There are 34 known isotopes of krypton (₃₆Kr) with atomic mass numbers from 69 through 102. Naturally occurring krypton is made of five stable isotopes and one () which is slightly radioactive with an extremely long half-life, plus traces of radioisotopes that are produced by cosmic rays in the

atmosphere An atmosphere () is a layer of gas or layers of gases that envelop a planet, and is held in place by the gravity of the planetary body. A planet retains an atmosphere when the gravity is great and the temperature of the atmosphere is low. A s ...

List of isotopes

, - , ⁶⁹Kr , style="text-align:right" , 36 , style="text-align:right" , 33 , 68.96518(43)# , 32(10) ms , β⁺ , ⁶⁹Br , 5/2−# , , , - , ⁷⁰Kr , style="text-align:right" , 36 , style="text-align:right" , 34 , 69.95526(41)# , 52(17) ms , β⁺ , ⁷⁰Br , 0+ , , , - , rowspan=2, ⁷¹Kr , rowspan=2 style="text-align:right" , 36 , rowspan=2 style="text-align:right" , 35 , rowspan=2, 70.94963(70) , rowspan=2, 100(3) ms , β⁺ (94.8%) , ⁷¹Br , rowspan=2, (5/2)− , rowspan=2, , rowspan=2, , - , β⁺, p (5.2%) , ⁷⁰Se , - , ⁷²Kr , style="text-align:right" , 36 , style="text-align:right" , 36 , 71.942092(9) , 17.16(18) s , β⁺ , ⁷²Br , 0+ , , , - , rowspan=2, ⁷³Kr , rowspan=2 style="text-align:right" , 36 , rowspan=2 style="text-align:right" , 37 , rowspan=2, 72.939289(7) , rowspan=2, 28.6(6) s , β⁺ (99.32%) , ⁷³Br , rowspan=2, 3/2− , rowspan=2, , rowspan=2, , - , β⁺, p (.68%) , ⁷²Se , - , style="text-indent:1em" , ^73mKr , colspan="3" style="text-indent:2em" , 433.66(12) keV , 107(10) ns , , , (9/2+) , , , - , ⁷⁴Kr , style="text-align:right" , 36 , style="text-align:right" , 38 , 73.9330844(22) , 11.50(11) min , β⁺ , ⁷⁴Br , 0+ , , , - , ⁷⁵Kr , style="text-align:right" , 36 , style="text-align:right" , 39 , 74.930946(9) , 4.29(17) min , β⁺ , ⁷⁵Br , 5/2+ , , , - , ⁷⁶Kr , style="text-align:right" , 36 , style="text-align:right" , 40 , 75.925910(4) , 14.8(1) h , β⁺ , ⁷⁶Br , 0+ , , , - , ⁷⁷Kr , style="text-align:right" , 36 , style="text-align:right" , 41 , 76.9246700(21) , 74.4(6) min , β⁺ , ⁷⁷Br , 5/2+ , , , - , ⁷⁸Kr

Primordial Primordial may refer to: * Primordial era, an era after the Big Bang. See Chronology of the universe * Primordial sea (a.k.a. primordial ocean, ooze or soup). See Abiogenesis * Primordial nuclide, nuclides, a few radioactive, that formed before ...

radionuclide A radionuclide (radioactive nuclide, radioisotope or radioactive isotope) is a nuclide that has excess nuclear energy, making it unstable. This excess energy can be used in one of three ways: emitted from the nucleus as gamma radiation; transfer ...

, style="text-align:right" , 36 , style="text-align:right" , 42 , 77.9203648(12) , align=center, 9.2 y , Double EC , ⁷⁸Se , 0+ , 0.00355(3) , , - , ⁷⁹Kr , style="text-align:right" , 36 , style="text-align:right" , 43 , 78.920082(4) , 35.04(10) h , β⁺ , ⁷⁹Br , 1/2− , , , - , style="text-indent:1em" , ^79mKr , colspan="3" style="text-indent:2em" , 129.77(5) keV , 50(3) s , , , 7/2+ , , , - , ⁸⁰Kr , style="text-align:right" , 36 , style="text-align:right" , 44 , 79.9163790(16) , colspan=3 align=center, Stable , 0+ , 0.02286(10) , , - , ⁸¹KrUsed to date groundwater , style="text-align:right" , 36 , style="text-align:right" , 45 , 80.9165920(21) , 2.29(11)×10⁵ y , EC , ⁸¹Br , 7/2+ , trace , , - , rowspan=2 style="text-indent:1em" , ^81mKr , rowspan=2 colspan="3" style="text-indent:2em" , 190.62(4) keV , rowspan=2, 13.10(3) s , IT (99.975%) , ⁸¹Kr , rowspan=2, 1/2− , rowspan=2, , rowspan=2, , - , EC (.025%) , ⁸¹Br , - , ⁸²Kr , style="text-align:right" , 36 , style="text-align:right" , 46 , 81.9134836(19) , colspan=3 align=center, Stable , 0+ , 0.11593(31) , , - , ⁸³Kr

Fission product Nuclear fission products are the atomic fragments left after a large atomic nucleus undergoes nuclear fission. Typically, a large nucleus like that of uranium fissions by splitting into two smaller nuclei, along with a few neutrons, the release ...

, style="text-align:right" , 36 , style="text-align:right" , 47 , 82.914136(3) , colspan=3 align=center, Stable , 9/2+ , 0.11500(19) , , - , style="text-indent:1em" , ^83m1Kr , colspan="3" style="text-indent:2em" , 9.4053(8) keV , 154.4(11) ns , , , 7/2+ , , , - , style="text-indent:1em" , ^83m2Kr , colspan="3" style="text-indent:2em" , 41.5569(10) keV , 1.83(2) h , IT , ⁸³Kr , 1/2− , , , - , ⁸⁴Kr , style="text-align:right" , 36 , style="text-align:right" , 48 , 83.911507(3) , colspan=3 align=center, Stable , 0+ , 0.56987(15) , , - , style="text-indent:1em" , ^84mKr , colspan="3" style="text-indent:2em" , 3236.02(18) keV , 1.89(4) µs , , , 8+ , , , - , ⁸⁵Kr , style="text-align:right" , 36 , style="text-align:right" , 49 , 84.9125273(21) , 10.776(3) y , β⁻ , ⁸⁵Rb , 9/2+ , trace , , - , rowspan=2 style="text-indent:1em" , ^85m1Kr , rowspan=2 colspan="3" style="text-indent:2em" , 304.871(20) keV , rowspan=2, 4.480(8) h , β⁻ (78.6%) , ⁸⁵Rb , rowspan=2, 1/2− , rowspan=2, , rowspan=2, , - , IT (21.4%) , ⁸⁵Kr , - , style="text-indent:1em" , ^85m2Kr , colspan="3" style="text-indent:2em" , 1991.8(13) keV , 1.6(7) µs
.2(+10-4) µs, , , (17/2+) , , , - , ⁸⁶KrFormerly used to define the meter , style="text-align:right" , 36 , style="text-align:right" , 50 , 85.91061073(11) , colspan=3 align=center, Observationally StableBelieved to decay by β⁻β⁻ to ⁸⁶Sr , 0+ , 0.17279(41) , , - , ⁸⁷Kr , style="text-align:right" , 36 , style="text-align:right" , 51 , 86.91335486(29) , 76.3(5) min , β⁻ , ''⁸⁷Rb'' , 5/2+ , , , - , ⁸⁸Kr , style="text-align:right" , 36 , style="text-align:right" , 52 , 87.914447(14) , 2.84(3) h , β⁻ , ⁸⁸Rb , 0+ , , , - , ⁸⁹Kr , style="text-align:right" , 36 , style="text-align:right" , 53 , 88.91763(6) , 3.15(4) min , β⁻ , ⁸⁹Rb , 3/2(+#) , , , - , ⁹⁰Kr , style="text-align:right" , 36 , style="text-align:right" , 54 , 89.919517(20) , 32.32(9) s , β⁻ , ^90mRb , 0+ , , , - , ⁹¹Kr , style="text-align:right" , 36 , style="text-align:right" , 55 , 90.92345(6) , 8.57(4) s , β⁻ , ⁹¹Rb , 5/2(+) , , , - , rowspan=2, ⁹²Kr , rowspan=2 style="text-align:right" , 36 , rowspan=2 style="text-align:right" , 56 , rowspan=2, 91.926156(13) , rowspan=2, 1.840(8) s , β⁻ (99.96%) , ⁹²Rb , rowspan=2, 0+ , rowspan=2, , rowspan=2, , - , β⁻, n (.033%) , ⁹¹Rb , - , rowspan=2, ⁹³Kr , rowspan=2 style="text-align:right" , 36 , rowspan=2 style="text-align:right" , 57 , rowspan=2, 92.93127(11) , rowspan=2, 1.286(10) s , β⁻ (98.05%) , ⁹³Rb , rowspan=2, 1/2+ , rowspan=2, , rowspan=2, , - , β⁻, n (1.95%) , ⁹²Rb , - , rowspan=2, ⁹⁴Kr , rowspan=2 style="text-align:right" , 36 , rowspan=2 style="text-align:right" , 58 , rowspan=2, 93.93436(32)# , rowspan=2, 210(4) ms , β⁻ (94.3%) , ⁹⁴Rb , rowspan=2, 0+ , rowspan=2, , rowspan=2, , - , β⁻, n (5.7%) , ⁹³Rb , - , ⁹⁵Kr , style="text-align:right" , 36 , style="text-align:right" , 59 , 94.93984(43)# , 114(3) ms , β⁻ , ⁹⁵Rb , 1/2(+) , , , - , ⁹⁶Kr , style="text-align:right" , 36 , style="text-align:right" , 60 , 95.942998(62) , 80(7) ms , β⁻ , ⁹⁶Rb , 0+ , , , - , rowspan=2, ⁹⁷Kr , rowspan=2 style="text-align:right" , 36 , rowspan=2 style="text-align:right" , 61 , rowspan=2, 96.94856(54)# , rowspan=2, 63(4) ms , β⁻ , ⁹⁷Rb , rowspan=2, 3/2+# , rowspan=2, , rowspan=2, , - , β⁻, n , ⁹⁶Rb , - , ⁹⁸Kr , style="text-align:right" , 36 , style="text-align:right" , 62 , 97.95191(64)# , 46(8) ms , , , 0+ , , , - , ⁹⁹Kr , style="text-align:right" , 36 , style="text-align:right" , 63 , 98.95760(64)# , 40(11) ms , , , (3/2+)# , , , - , ¹⁰⁰Kr , style="text-align:right" , 36 , style="text-align:right" , 64 , 99.96114(54)# , 10# ms
300 ns, , , 0+ , , , - , rowspan=3 , ¹⁰¹Kr , rowspan=3 , 36 , rowspan=3 , 65 , rowspan=3 , unknown , rowspan=3 , >635 ns , β⁻, 2n , ⁹⁹Rb , rowspan=3 , unknown , rowspan=3 , , rowspan=3 , , - , β⁻, n , ¹⁰⁰Rb , - , β⁻ , ¹⁰¹Rb , - , ¹⁰²Kr , style="text-align:right" , 36 , style="text-align:right" , 66 , , , , , 0+ , , * The isotopic composition refers to that in air.

Notable isotopes

Krypton-81

Radioactive krypton-81 is the product of

spallation reaction Spallation is a process in which fragments of material (spall) are ejected from a body due to impact or stress. In the context of impact mechanics it describes ejection of material from a target during impact by a projectile. In planetary p ...

s with cosmic rays striking gases present in the Earth atmosphere, along with the six stable or nearly stable krypton isotopes. Krypton-81 has a half-life of about 229,000 years. Krypton-81 is used for dating ancient (50,000- to 800,000-year-old) groundwater and to determine their residence time in deep aquifers. One of the main technical limitation of the method is that it requires to sample very large volumes of water: several hundred liters or a few cubic meters of water. This is particularly challenging for dating pore water in deep clay aquitards with very low hydraulic conductivity.

Krypton-85

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 Nuclear fission is a reaction in which the nucleus of an atom splits into two or more smaller nuclei. The fission process often produces gamma photons, and releases a very large amount of energy even by the energetic standards of radio ...

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.

Atmospheric concentration

The atmospheric concentration of krypton-85 around the North Pole is about 30 percent higher than that at the

Amundsen–Scott South Pole Station The Amundsen–Scott South Pole Station is the United States scientific research station at the South Pole of the Earth. It is the southernmost point under the jurisdiction (not sovereignty) of the United States. The station is located on the ...

because nearly all of the world's nuclear reactors and all of its major nuclear reprocessing plants are located in the

northern hemisphere The Northern Hemisphere is the half of Earth that is north of the Equator. For other planets in the Solar System, north is defined as being in the same celestial hemisphere relative to the invariable plane of the solar system as Earth's Nort ...

, and also well-north of the

equator The equator is a circle of latitude, about in circumference, that divides Earth into the Northern and Southern hemispheres. It is an imaginary line located at 0 degrees latitude, halfway between the North and South poles. The term can als ...

. To be more specific, those

nuclear reprocessing Nuclear reprocessing is the chemical separation of fission products and actinides from spent nuclear fuel. Originally, reprocessing was used solely to extract plutonium for producing nuclear weapons. With commercialization of nuclear power, the ...

plants with significant capacities are located in the United States, the United Kingdom, the

French Republic France (), officially the French Republic ( ), is a country primarily located in Western Europe. It also comprises of overseas regions and territories in the Americas and the Atlantic, Pacific and Indian Oceans. Its metropolitan area ...

, the Russian Federation, Mainland China (PRC),

Japan Japan ( ja, 日本, or , and formally , ''Nihonkoku'') is an island country in East Asia. It is situated in the northwest Pacific Ocean, and is bordered on the west by the Sea of Japan, while extending from the Sea of Okhotsk in the north ...

, 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.

Others

All other radioisotopes of krypton have half-lives of less than one day, except for krypton-79, a positron emitter with a half-life of about 35.0 hours.

References

* Isotope masses from: ** * Isotopic compositions and standard atomic masses from: ** ** * Half-life, spin, and isomer data selected from the following sources. ** ** **

External links

Brookhaven National Laboratory: Krypton-101 information
{{Navbox element isotopes Krypton Krypton