Isotopes of cobalt

Nuclides with atomic number of 27 but with different mass numbers

Isotopes of cobalt (27Co) | Main isotopes[1] | Decay

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| abun­dance | half-life (t1/2) | mode | pro­duct
56Co  | synth | 77.236 d | β+ | 56Fe
57Co  | synth  | 271.811 d | ε | 57Fe
58Co  | synth  | 70.844 d | β+ | 58Fe
59Co  | 100%  | stable
60Co | trace | 5.2714 y | β−100% | 60Ni
Standard atomic weight Ar°(Co)

* 58.933194±0.000003[2]
* 58.933±0.001 (abridged)[3]

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Naturally occurring cobalt, Co, consists of a single stable isotope, 59Co (thus, cobalt is a mononuclidic element). Twenty-eight radioisotopes have been characterized; the most stable are 60Co with a half-life of 5.2714 years, 57Co (271.8 days), 56Co (77.27 days), and 58Co (70.86 days). All other isotopes have half-lives of less than 18 hours and most of these have half-lives of less than 1 second. This element also has 11 meta states, all of which have half-lives of less than 15 minutes.

The isotopes of cobalt range in atomic weight from 47Co to 75Co. The main decay mode for isotopes with atomic mass less than that of the stable isotope, 59Co, is electron capture and the main mode of decay for those of greater than 59 atomic mass units is beta decay. The main decay products before 59Co are iron isotopes and the main products after are nickel isotopes.

Radioisotopes can be produced by various nuclear reactions. For example, 57Co is produced by cyclotron irradiation of iron. The main reaction is the (d,n) reaction 56Fe + 2H → n + 57Co.[4]

## List of isotopes[edit]

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

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Excitation energy[n 4] | Normal proportion  | Range of variation
47Co  | 27  | 20  | 47.01149(54)#  |  |  |  | 7/2−#  |  |
48Co  | 27  | 21  | 48.00176(43)#  |  | p | 47Fe  | 6+#  |  |
49Co  | 27  | 22  | 48.98972(28)#  | <35 ns  | p (>99.9%)  | 48Fe  | 7/2−#  |  |
β+ (<.1%)  | 49Fe
50Co  | 27  | 23  | 49.98154(18)#  | 44(4) ms  | β+, p (54%)  | 49Mn  | (6+)  |  |
β+ (46%)  | 50Fe
51Co  | 27  | 24  | 50.97072(16)#  | 60# ms [>200 ns]  | β+ | 51Fe  | 7/2−#  |  |
52Co  | 27  | 25  | 51.96359(7)#  | 115(23) ms  | β+ | 52Fe  | (6+)  |  |
52mCo  | 380(100)# keV  | 104(11)# ms  | β+ | 52Fe  | 2+#  |  |
IT | 52Co
53Co  | 27  | 26  | 52.954219(19)  | 242(8) ms  | β+ | 53Fe  | 7/2−#  |  |
53mCo  | 3197(29) keV  | 247(12) ms  | β+ (98.5%)  | 53Fe  | (19/2−)  |  |
p (1.5%)  | 52Fe
54Co  | 27  | 27  | 53.9484596(8)  | 193.28(7) ms  | β+ | 54Fe | 0+  |  |
54mCo  | 197.4(5) keV  | 1.48(2) min  | β+ | 54Fe | (7)+  |  |
55Co  | 27  | 28  | 54.9419990(8)  | 17.53(3) h  | β+ | 55Fe  | 7/2−  |  |
56Co  | 27  | 29  | 55.9398393(23)  | 77.233(27) d  | β+ | 56Fe | 4+  |  |
57Co  | 27  | 30  | 56.9362914(8)  | 271.74(6) d  | EC | 57Fe | 7/2−  |  |
58Co  | 27  | 31  | 57.9357528(13)  | 70.86(6) d  | β+ | 58Fe | 2+  |  |
58m1Co  | 24.95(6) keV  | 9.04(11) h  | IT  | 58Co  | 5+  |  |
58m2Co  | 53.15(7) keV  | 10.4(3) μs  |  |  | 4+  |  |
59Co  | 27  | 32  | 58.9331950(7)  | Stable | 7/2−  | 1.0000  |
60Co | 27  | 33  | 59.9338171(7)  | 5.2714(6) y  | β−, γ  | 60Ni | 5+  |  |
60mCo  | 58.59(1) keV  | 10.467(6) min  | IT (99.76%)  | 60Co  | 2+  |  |
β− (.24%)  | 60Ni
61Co  | 27  | 34  | 60.9324758(10)  | 1.650(5) h  | β− | 61Ni | 7/2−  |  |
62Co  | 27  | 35  | 61.934051(21)  | 1.50(4) min  | β− | 62Ni | 2+  |  |
62mCo  | 22(5) keV  | 13.91(5) min  | β− (99%)  | 62Ni | 5+  |  |
IT (1%)  | 62Co
63Co  | 27  | 36  | 62.933612(21)  | 26.9(4) s  | β− | 63Ni  | 7/2−  |  |
64Co  | 27  | 37  | 63.935810(21)  | 0.30(3) s  | β− | 64Ni | 1+  |  |
65Co  | 27  | 38  | 64.936478(14)  | 1.20(6) s  | β− | 65Ni  | (7/2)−  |  |
66Co  | 27  | 39  | 65.93976(27)  | 0.18(1) s  | β− | 66Ni  | (3+)  |  |
66m1Co  | 175(3) keV  | 1.21(1) μs  |  |  | (5+)  |  |
66m2Co  | 642(5) keV  | >100 μs  |  |  | (8-)  |  |
67Co  | 27  | 40  | 66.94089(34)  | 0.425(20) s  | β− | 67Ni  | (7/2−)#  |  |
68Co  | 27  | 41  | 67.94487(34)  | 0.199(21) s  | β− | 68Ni  | (7-)  |  |
68mCo  | 150(150)# keV  | 1.6(3) s  |  |  | (3+)  |  |
69Co  | 27  | 42  | 68.94632(36)  | 227(13) ms  | β− (>99.9%)  | 69Ni  | 7/2−#  |  |
β−, n (<.1%)  | 68Ni
70Co  | 27  | 43  | 69.9510(9)  | 119(6) ms  | β− (>99.9%)  | 70Ni  | (6-)  |  |
β−, n (<.1%)  | 69Ni
70mCo  | 200(200)# keV  | 500(180) ms  |  |  | (3+)  |  |
71Co  | 27  | 44  | 70.9529(9)  | 97(2) ms  | β− (>99.9%)  | 71Ni  | 7/2−#  |  |
β−, n (<.1%)  | 70Ni
72Co  | 27  | 45  | 71.95781(64)#  | 62(3) ms  | β− (>99.9%)  | 72Ni  | (6- ,7-)  |  |
β−, n (<.1%)  | 71Ni
73Co  | 27  | 46  | 72.96024(75)#  | 41(4) ms  |  |  | 7/2−#  |  |
74Co  | 27  | 47  | 73.96538(86)#  | 50# ms [>300 ns]  |  |  | 0+  |  |
75Co  | 27  | 48  | 74.96833(86)#  | 40# ms [>300 ns]  |  |  | 7/2−#  |  |
This table header & footer:

* view

1. ^ mCo - 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. ^ a b c # - Values marked # are not purely derived from experimental data, but at least partly from trends of neighboring nuclides (TNN).
5. ^ Modes of decay:  EC: | Electron capture

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IT: | Isomeric transition
n: | Neutron emission
p: | Proton emission
6. ^ Bold symbol as daughter - Daughter product is stable.
7. ^ ( ) spin value - Indicates spin with weak assignment arguments.

## Stellar nucleosynthesis of cobalt-56[edit]

One of the terminal nuclear reactions in stars prior to supernova produces 56Ni. Following its production, 56Ni decays to 56Co, and then 56Co subsequently decays to 56Fe. These decay reactions power the luminosity displayed in light decay curves. Both the light decay and radioactive decay curves are expected to be exponential. Therefore, the light decay curve should give an indication of the nuclear reactions powering it. This has been confirmed by observation of bolometric light decay curves for SN 1987A. Between 600 and 800 days after SN1987A occurred, the bolometric light curve decreased at an exponential rate with half-life values from τ1/2 = 68.6 days to τ1/2 = 69.6 days.[5] The rate at which the luminosity decreased closely matched the exponential decay of 56Co with a half-life of τ1/2 = 77.233 days.

## Use of cobalt radioisotopes in medicine [edit]

Cobalt-57 (57Co or Co-57) is used in medical tests; it is used as a radiolabel for vitamin B12 uptake. It is useful for the Schilling test.[6]

Cobalt-60 (60Co or Co-60) is used in radiotherapy. It produces two gamma rays with energies of 1.17 MeV and 1.33 MeV. The 60Co source is about 2 cm in diameter and as a result produces a geometric penumbra, making the edge of the radiation field fuzzy. The metal has the unfortunate habit of producing fine dust, causing problems with radiation protection. The 60Co source is useful for about 5 years but even after this point is still very radioactive, and so cobalt machines have fallen from favor in the Western world where Linacs are common.

## Industrial uses for radioactive isotopes[edit]

Cobalt-60 (60Co) is useful as a gamma ray source because it can be produced in predictable quantities, and for its high radioactivity simply by exposing natural cobalt to neutrons in a reactor.[7] The uses for industrial cobalt include:

* Sterilization of medical supplies and medical waste
* Radiation treatment of foods for sterilization (cold pasteurization)[8]
* Industrial radiography (e.g., weld integrity radiographs)
* Density measurements (e.g., concrete density measurements)
* Tank fill height switches

57Co is used as a source in Mössbauer spectroscopy of iron-containing samples. Electron capture by 57Co forms an excited state of the 57Fe nucleus, which in turn decays to the ground state with the emission of a gamma ray. Measurement of the gamma-ray spectrum provides information about the chemical state of the iron atom in the sample.

## References[edit]

1. ^ 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. ^ "Standard Atomic Weights: Cobalt". CIAAW. 2017.
3. ^ 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.
4. ^ Diaz, L. E. "Cobalt-57: Production". JPNM Physics Isotopes. University of Harvard. Archived from the original on 2000-10-31. Retrieved 2013-11-15.
5. ^ Bouchet, P.; Danziger, I.J.; Lucy, L.B. (September 1991). "Bolometric Light Curve of SN 1987A: Results from Day 616 to 1316 After Outburst". The Astronomical Journal. 102 (3): 1135–1146 - via Astrophysics Data System.
6. ^ Diaz, L. E. "Cobalt-57: Uses". JPNM Physics Isotopes. University of Harvard. Archived from the original on 2011-06-11. Retrieved 2010-09-13.
7. ^ "Properties of Cobalt-60". Radioactive Isotopes. Retrieved 2022-12-09.
8. ^ "Beneficial Uses of Cobalt-60". INTERNATIONAL IRRADIATION ASSOCIATION. Retrieved 2022-12-09.

* Isotope masses from:
* Audi, Georges; Bersillon, Olivier; Blachot, Jean; Wapstra, Aaldert Hendrik (2003), "The NUBASE evaluation of nuclear and decay properties", 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:
* de Laeter, John Robert; Böhlke, John Karl; De Bièvre, Paul; Hidaka, Hiroshi; Peiser, H. Steffen; Rosman, Kevin J. R.; Taylor, Philip D. P. (2003). "Atomic weights of the elements. Review 2000 (IUPAC Technical Report)". Pure and Applied Chemistry. 75 (6): 683–800. doi:10.1351/pac200375060683.
* Wieser, Michael E. (2006). "Atomic weights of the elements 2005 (IUPAC Technical Report)". Pure and Applied Chemistry. 78 (11): 2051–2066. doi:10.1351/pac200678112051.
* "News & Notices: Standard Atomic Weights Revised". International Union of Pure and Applied Chemistry. 19 October 2005.
* Half-life, spin, and isomer data selected from the following sources.
* Audi, Georges; Bersillon, Olivier; Blachot, Jean; Wapstra, Aaldert Hendrik (2003), "The NUBASE evaluation of nuclear and decay properties", Nuclear Physics A, 729: 3–128, Bibcode:2003NuPhA.729....3A, doi:10.1016/j.nuclphysa.2003.11.001
* National Nuclear Data Center. "NuDat 2.x database". Brookhaven National Laboratory.
* Holden, Norman E. (2004). "11. Table of the Isotopes". In Lide, David R. (ed.). CRC Handbook of Chemistry and Physics (85th ed.). Boca Raton, Florida: CRC Press. ISBN 978-0-8493-0485-9.

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Isotopes of the chemical elements

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* Table of nuclides
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