:Isotopes of cobalt

Naturally occurring cobalt, Co, consists of a single stable isotope, {{sup|59}}Co (thus, cobalt is a mononuclidic element). Twenty-eight radioisotopes have been characterized; the most stable are Cobalt-60 with a half-life of 5.2714 years, {{sup|57}}Co (271.811 days), {{sup|56}}Co (77.236 days), and {{sup|58}}Co (70.844 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 19 meta states, of which the most stable is ^58m1Co with a half-life of 8.853 h.

The isotopes of cobalt range in atomic weight from {{sup|50}}Co to {{sup|78}}Co. The main decay mode for isotopes with atomic mass less than that of the stable isotope, {{sup|59}}Co, 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 {{sup|59}}Co are iron isotopes and the main products after are nickel isotopes.

Radioisotopes can be produced by various nuclear reactions. For example, {{sup|57}}Co is produced by cyclotron irradiation of iron. The main reaction is the (d,n) reaction {{sup|56}}Fe + deuterium → n + {{sup|57}}Co.{{cite web

|first1=L. E.

|last1=Diaz

|url=http://www.med.harvard.edu/JPNM/physics/isotopes/Co/Co57/prod.html

|title=Cobalt-57: Production

|work=JPNM Physics Isotopes

|publisher=University of Harvard

|access-date=2013-11-15

|archive-date=2000-10-31

|archive-url=https://web.archive.org/web/20001031195522/http://www.med.harvard.edu/JPNM/physics/isotopes/Co/Co57/prod.html

|url-status=dead

}}

List of isotopes

{{Isotopes table

|symbol=Co

|refs=NUBASE2020, AME2020 II

|notes=m, unc(), hl#, mass#, exen#, spin(), spin#, daughter-st, p, n, IT, EC

}}

|-id=Cobalt-50

| rowspan=3|{{sup|50}}Co

| rowspan=3 style="text-align:right" | 27

| rowspan=3 style="text-align:right" | 23

| rowspan=3|49.98112(14)

| rowspan=3|38.8(2) ms

| β{{sup|+}}, p (70.5%)

| {{sup|49}}Mn

| rowspan=3|(6+)

| rowspan=3|

| β{{sup|+}} (29.5%)

| {{sup|50}}Fe

| β{{sup|+}}, 2p?

| {{sup|48}}Cr

|-id=Cobalt-51

| rowspan=2|{{sup|51}}Co

| rowspan=2 style="text-align:right" | 27

| rowspan=2 style="text-align:right" | 24

| rowspan=2|50.970647(52)

| rowspan=2|68.8(19) ms

| β{{sup|+}} (96.2%)

| {{sup|51}}Fe

| rowspan=2|7/2−

| rowspan=2|

| β{{sup|+}}, p (<3.8%)

| {{sup|50}}Mn

|-id=Cobalt-52

| rowspan=2|{{sup|52}}Co

| rowspan=2 style="text-align:right" | 27

| rowspan=2 style="text-align:right" | 25

| rowspan=2|51.9631302(57)

| rowspan=2|111.7(21) ms

| β{{sup|+}}

| {{sup|52}}Fe

| rowspan=2|6+

| rowspan=2|

| β{{sup|+}}, p?

| {{sup|51}}Mn

|-id=Cobalt-52m

| rowspan=3 style="text-indent:1em" | {{sup|52m}}Co

| rowspan=3 colspan="3" style="text-indent:2em" | 376(9) keV

| rowspan=3|102(5) ms

| β{{sup|+}}

| {{sup|52}}Fe

| rowspan=3|2+

| rowspan=3|

| IT?

| {{sup|52}}Co

| β{{sup|+}}, p?

| {{sup|51}}Mn

|-id=Cobalt-53

| {{sup|53}}Co

| style="text-align:right" | 27

| style="text-align:right" | 26

| 52.9542033(19)

| 244.6(28) ms

| β{{sup|+}}

| {{sup|53}}Fe

| 7/2−#

|-id=Cobalt-53m

| rowspan=2 style="text-indent:1em" | {{sup|53m}}Co

| rowspan=2 colspan="3" style="text-indent:2em" | 3174.3(9) keV

| rowspan=2|250(10) ms

| β{{sup|+}}? (~98.5%)

| {{sup|53}}Fe

| rowspan=2|(19/2−)

| rowspan=2|

| p (~1.5%)

| {{sup|52}}Fe

|-id=Cobalt-54

| {{sup|54}}Co

| style="text-align:right" | 27

| 53.94845908(38)

| 193.27(6) ms

| β{{sup|+}}

| {{sup|54}}Fe

| 0+

|-id=Cobalt-54m

| style="text-indent:1em" | {{sup|54m}}Co

| colspan="3" style="text-indent:2em" | 197.57(10) keV

| 1.48(2) min

| β{{sup|+}}

| {{sup|54}}Fe

| 7+

|-id=Cobalt-55

| {{sup|55}}Co

| style="text-align:right" | 27

| style="text-align:right" | 28

| 54.94199642(43)

| 17.53(3) h

| β{{sup|+}}

| {{sup|55}}Fe

| 7/2−

|-id=Cobalt-56

| {{sup|56}}Co

| style="text-align:right" | 27

| style="text-align:right" | 29

| 55.93983803(51)

| 77.236(26) d

| β{{sup|+}}

| {{sup|56}}Fe

| 4+

| {{sup|57}}Co

| style="text-align:right" | 27

| style="text-align:right" | 30

| 56.93628982(55)

| 271.811(32) d

| EC

| {{sup|57}}Fe

| 7/2−

|-id=Cobalt-58

| rowspan=2|{{sup|58}}Co

| rowspan=2 style="text-align:right" | 27

| rowspan=2 style="text-align:right" | 31

| rowspan=2|57.9357513(12)

| rowspan=2|70.844(20) d

| EC (85.21%)

| {{sup|58}}Fe

| rowspan=2|2+

| rowspan=2|

| β{{sup|+}} (14.79%)

| {{sup|58}}Fe

|-id=Cobalt-58m1

| rowspan=2 style="text-indent:1em" | {{sup|58m1}}Co

| rowspan=2 colspan="3" style="text-indent:2em" | 24.95(6) keV

| rowspan=2|8.853(23) h

| IT

| {{sup|58}}Co

| rowspan=2|5+

| rowspan=2|

| EC (0.00120%)

| {{sup|58}}Fe

|-id=Cobalt-58m2

| style="text-indent:1em" | {{sup|58m2}}Co

| colspan="3" style="text-indent:2em" | 53.15(7) keV

| 10.5(3) μs

| IT

| {{sup|58}}Co

| 4+

|-id=Cobalt-59

| {{sup|59}}Co

| style="text-align:right" | 27

| style="text-align:right" | 32

| 58.93319352(43)

| colspan="3" style="text-align:center;"|Stable

| 7/2−

| 1.0000

| Cobalt-60

| style="text-align:right" | 27

| style="text-align:right" | 33

| 59.93381554(43)

| 5.2714(6) y

| β{{sup|−}}

| {{sup|60}}Ni

| 5+

|-id=Cobalt-60m

| rowspan=2 style="text-indent:1em" | {{sup|60m}}Co

| rowspan=2 colspan="3" style="text-indent:2em" | 58.59(1) keV

| rowspan=2|10.467(6) min

| IT (99.75%)

| {{sup|60}}Co

| rowspan=2|2+

| rowspan=2|

| β{{sup|−}} (0.25%)

| {{sup|60}}Ni

|-id=Cobalt-61

| {{sup|61}}Co

| style="text-align:right" | 27

| style="text-align:right" | 34

| 60.93247603(90)

| 1.649(5) h

| β{{sup|−}}

| {{sup|61}}Ni

| 7/2−

|-id=Cobalt-62

| {{sup|62}}Co

| style="text-align:right" | 27

| style="text-align:right" | 35

| 61.934058(20)

| 1.54(10) min

| β{{sup|−}}

| {{sup|62}}Ni

| (2)+

|-id=Cobalt-62m

| rowspan=2 style="text-indent:1em" | {{sup|62m}}Co

| rowspan=2 colspan="3" style="text-indent:2em" | 22(5) keV

| rowspan=2|13.86(9) min

| β{{sup|−}} (>99.5%)

| {{sup|62}}Ni

| rowspan=2|(5)+

| rowspan=2|

| IT (<0.5%)

| {{sup|62}}Co

|-id=Cobalt-63

| {{sup|63}}Co

| style="text-align:right" | 27

| style="text-align:right" | 36

| 62.933600(20)

| 26.9(4) s

| β{{sup|−}}

| {{sup|63}}Ni

| 7/2−

|-id=Cobalt-64

| {{sup|64}}Co

| style="text-align:right" | 27

| style="text-align:right" | 37

| 63.935810(21)

| 300(30) ms

| β{{sup|−}}

| {{sup|64}}Ni

| 1+

|-id=Cobalt-64m

| rowspan=2 style="text-indent:1em" | {{sup|64m}}Co

| rowspan=2 colspan="3" style="text-indent:2em" | 107(20) keV

| rowspan=2|300# ms

| β{{sup|−}}?

| {{sup|64}}Ni

| rowspan=2|5+#

| rowspan=2|

| IT?

| {{sup|64}}Co

|-id=Cobalt-65

| {{sup|65}}Co

| style="text-align:right" | 27

| style="text-align:right" | 38

| 64.9364621(22)

| 1.16(3) s

| β{{sup|−}}

| {{sup|65}}Ni

| (7/2)−

|-id=Cobalt-66

| rowspan=2|{{sup|66}}Co

| rowspan=2 style="text-align:right" | 27

| rowspan=2 style="text-align:right" | 39

| rowspan=2|65.939443(15)

| rowspan=2|194(17) ms

| β{{sup|−}}

| {{sup|66}}Ni

| rowspan=2|(1+)

| rowspan=2|

| β{{sup|−}}, n?

| {{sup|65}}Ni

|-id=Cobalt-66m1

| style="text-indent:1em" | {{sup|66m1}}Co

| colspan="3" style="text-indent:2em" | 175.1(3) keV

| 824(22) ns

| IT

| ⁶⁶Co

| (3+)

|-id=Cobalt-66m2

| style="text-indent:1em" | {{sup|66m2}}Co

| colspan="3" style="text-indent:2em" | 642(5) keV

| >100 μs

| IT

| ⁶⁶Co

| (8−)

|-id=Cobalt-67

| rowspan=2|{{sup|67}}Co

| rowspan=2 style="text-align:right" | 27

| rowspan=2 style="text-align:right" | 40

| rowspan=2|66.9406096(69)

| rowspan=2|329(28) ms

| β{{sup|−}}

| {{sup|67}}Ni

| rowspan=2|(7/2−)

| rowspan=2|

| β{{sup|−}}, n?

| {{sup|66}}Ni

|-id=Cobalt-67m

| rowspan=2 style="text-indent:1em" | {{sup|67m}}Co

| rowspan=2 colspan="3" style="text-indent:2em" | 491.55(11) keV

| rowspan=2|496(33) ms

| IT (>80%)

| ⁶⁷Co

| rowspan=2|(1/2−)

| rowspan=2|

| β{{sup|−}}

| ⁶⁷Ni

|-id=Cobalt-68

| rowspan=2|{{sup|68}}Co

| rowspan=2 style="text-align:right" | 27

| rowspan=2 style="text-align:right" | 41

| rowspan=2|67.9445594(41)

| rowspan=2|200(20) ms

| β{{sup|−}}

| {{sup|68}}Ni

| rowspan=2|(7−)

| rowspan=2|

| β{{sup|−}}, n?

| {{sup|67}}Ni

|-id=Cobalt-68m1

| rowspan=2 style="text-indent:1em" | {{sup|68m1}}CoOrder of ground state and isomer is uncertain.

| rowspan=2 colspan="3" style="text-indent:2em" | 150(150)# keV

| rowspan=2|1.6(3) s

| β{{sup|−}}

| {{sup|68}}Ni

| rowspan=2|(2−)

| rowspan=2|

| β{{sup|−}}, n (>2.6%)

| {{sup|67}}Ni

|-id=Cobalt-68m2

| style="text-indent:1em" | {{sup|68m2}}Co

| colspan="3" style="text-indent:2em" | 195(150)# keV

| 101(10) ns

| IT

| ⁶⁸Co

| (1)

|-id=Cobalt-69

| rowspan=2|{{sup|69}}Co

| rowspan=2 style="text-align:right" | 27

| rowspan=2 style="text-align:right" | 42

| rowspan=2|68.945909(92)

| rowspan=2|180(20) ms

| β{{sup|−}}

| {{sup|69}}Ni

| rowspan=2|(7/2−)

| rowspan=2|

| β{{sup|−}}, n?

| {{sup|68}}Ni

|-id=Cobalt-69m

| style="text-indent:1em" | {{sup|69m}}Co

| colspan="3" style="text-indent:2em" | 170(90) keV

| 750(250) ms

| β{{sup|−}}

| {{sup|69}}Ni

| 1/2−#

|-id=Cobalt-70

| rowspan=3|{{sup|70}}Co

| rowspan=3 style="text-align:right" | 27

| rowspan=3 style="text-align:right" | 43

| rowspan=3|69.950053(12)

| rowspan=3|508(7) ms

| β{{sup|−}}

| {{sup|70}}Ni

| rowspan=3|(1+)

| rowspan=3|

| β{{sup|−}}, n?

| {{sup|69}}Ni

| β{{sup|−}}, 2n?

| {{sup|68}}Ni

|-id=Cobalt-70m

| rowspan=4 style="text-indent:1em" | {{sup|70m}}Co

| rowspan=4 colspan="3" style="text-indent:2em" | 200(200)# keV

| rowspan=4|112(7) ms

| β{{sup|−}}

| {{sup|70}}Ni

| rowspan=4|(7−)

| rowspan=4|

| IT?

| {{sup|70}}Co

| β{{sup|−}}, n?

| {{sup|69}}Ni

| β{{sup|−}}, 2n?

| {{sup|68}}Ni

|-id=Cobalt-71

| rowspan=2|{{sup|71}}Co

| rowspan=2 style="text-align:right" | 27

| rowspan=2 style="text-align:right" | 44

| rowspan=2|70.95237(50)

| rowspan=2|80(3) ms

| β{{sup|−}} (97%)

| {{sup|71}}Ni

| rowspan=2|(7/2−)

| rowspan=2|

| β{{sup|−}}, n (3%)

| {{sup|70}}Ni

|-id=Cobalt-72

| rowspan=3|{{sup|72}}Co

| rowspan=3 style="text-align:right" | 27

| rowspan=3 style="text-align:right" | 45

| rowspan=3|71.95674(32)#

| rowspan=3|51.5(3) ms

| β{{sup|−}} (<96%)

| {{sup|72}}Ni

| rowspan=3|(6−,7−)

| rowspan=3|

| β{{sup|−}}, n (>4%)

| {{sup|71}}Ni

| β{{sup|−}}, 2n?

| {{sup|70}}Ni

|-id=Cobalt-72m

| style="text-indent:1em" | {{sup|72m}}Co

| colspan="3" style="text-indent:2em" | 200(200)# keV

| 47.8(5) ms

| β{{sup|−}}

| {{sup|72}}Ni

| (0+,1+)

|-id=Cobalt-73

| rowspan=3|{{sup|73}}Co

| rowspan=3 style="text-align:right" | 27

| rowspan=3 style="text-align:right" | 46

| rowspan=3|72.95924(32)#

| rowspan=3|42.0(8) ms

| β{{sup|−}} (94%)

| {{sup|73}}Ni

| rowspan=3|(7/2−)

| rowspan=3|

| β{{sup|−}}, n (6%)

| {{sup|72}}Ni

| β{{sup|−}}, 2n?

| {{sup|71}}Ni

|-id=Cobalt-74

| rowspan=3|{{sup|74}}Co

| rowspan=3 style="text-align:right" | 27

| rowspan=3 style="text-align:right" | 47

| rowspan=3|73.96399(43)#

| rowspan=3|31.3(13) ms

| β{{sup|−}} (82%)

| {{sup|74}}Ni

| rowspan=3|7−#

| rowspan=3|

| β{{sup|−}}, n (18%)

| {{sup|73}}Ni

| β{{sup|−}}, 2n?

| {{sup|72}}Ni

|-id=Cobalt-75

| rowspan=3|{{sup|75}}Co

| rowspan=3 style="text-align:right" | 27

| rowspan=3 style="text-align:right" | 48

| rowspan=3|74.96719(43)#

| rowspan=3|26.5(12) ms

| β{{sup|−}} (>84%)

| {{sup|75}}Ni

| rowspan=3|7/2−#

| rowspan=3|

| β{{sup|−}}, n (<16%)

| {{sup|74}}Ni

| β{{sup|−}}, 2n?

| {{sup|73}}Ni

|-id=Cobalt-76

| rowspan=3|{{sup|76}}Co

| rowspan=3 style="text-align:right" | 27

| rowspan=3 style="text-align:right" | 49

| rowspan=3|75.97245(54)#

| rowspan=3|23(6) ms

| β{{sup|−}}

| {{sup|76}}Ni

| rowspan=3|(8−)

| rowspan=3|

| β{{sup|−}}, n?

| {{sup|75}}Ni

| β{{sup|−}}, 2n?

| {{sup|74}}Ni

|-id=Cobalt-76m1

| style="text-indent:1em" | {{sup|76m1}}Co

| colspan="3" style="text-indent:2em" | 100(100)# keV

| 16(4) ms

| β{{sup|−}}

| {{sup|76}}Ni

| (1−)

|-id=Cobalt-76m2

| style="text-indent:1em" | {{sup|76m2}}Co

| colspan="3" style="text-indent:2em" | 740(100)# keV

| 2.99(27) μs

| IT

| {{sup|76}}Co

| (3+)

|-id=Cobalt-77

| rowspan=4|{{sup|77}}Co

| rowspan=4 style="text-align:right" | 27

| rowspan=4 style="text-align:right" | 50

| rowspan=4|76.97648(64)#

| rowspan=4|15(6) ms

| β{{sup|−}}

| {{sup|77}}Ni

| rowspan=4|7/2−#

| rowspan=4|

| β{{sup|−}}, n?

| {{sup|76}}Ni

| β{{sup|−}}, 2n?

| {{sup|75}}Ni

| β{{sup|−}}, 3n?

| {{sup|74}}Ni

|-id=Cobalt-78

| {{sup|78}}Co

| style="text-align:right" | 27

| style="text-align:right" | 51

| 77.983 55(75)#

| 11# ms
[>410 ns]

| β{{sup|−}}?

| {{sup|78}}Ni

Stellar nucleosynthesis of cobalt-56

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 τ_1/2 = 68.6 days to τ_1/2 = 69.6 days.{{Cite journal |last1=Bouchet |first1=P. |last2=Danziger |first2=I.J. |last3=Lucy |first3=L.B. |date=September 1991 |title=Bolometric Light Curve of SN 1987A: Results from Day 616 to 1316 After Outburst |url=https://doi.org/10.1086/115939 |journal=The Astronomical Journal |volume=102 |issue=3 |pages=1135–1146 |doi=10.1086/115939 |via=Astrophysics Data System}} The rate at which the luminosity decreased closely matched the exponential decay of ⁵⁶Co with a half-life of τ_1/2 = 77.233 days.

Use of cobalt radioisotopes in medicine<span class="anchor" id="Cobalt-57"></span><span class="anchor" id="Cobalt-60"></span>

Cobalt-57 ({{sup|57}}Co or Co-57) is used in medical tests; it is used as a radiolabel for vitamin B{{sub|12}} uptake. It is useful for the Schilling test.{{cite web

|first1=L. E.

|last1=Diaz

|url=http://www.med.harvard.edu/JPNM/physics/isotopes/Co/Co57/uses.html

|title=Cobalt-57: Uses

|work=JPNM Physics Isotopes

|publisher=University of Harvard

|access-date=2010-09-13

|archive-date=2011-06-11

|archive-url=https://web.archive.org/web/20110611162615/http://www.med.harvard.edu/JPNM/physics/isotopes/Co/Co57/uses.html

|url-status=dead

}}

Cobalt-60 ({{sup|60}}Co or Co-60) is used in radiotherapy. It produces two gamma rays with energies of 1.17 MeV and 1.33 MeV. The {{sup|60}}Co 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 {{sup|60}}Co 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

Cobalt-60 ({{sup|60}}Co) 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.{{Cite web |title=Properties of Cobalt-60 |url=http://radioactiveisotopes.weebly.com/properties-of-cobalt-60.html |access-date=2022-12-09 |website=Radioactive Isotopes}} The uses for industrial cobalt include:

Sterilization of medical supplies and medical waste
Radiation treatment of foods for sterilization (cold pasteurization){{Cite web |title=Beneficial Uses of Cobalt-60 |url=https://iiaglobal.com/publications/beneficial-uses-of-cobalt-60-2/ |access-date=2022-12-09 |website=INTERNATIONAL IRRADIATION ASSOCIATION |language=en-US}}
Industrial radiography (e.g., weld integrity radiographs)
Density measurements (e.g., concrete density measurements)
Tank fill height switches

{{sup|57}}Co is used as a source in Mössbauer spectroscopy of iron-containing samples. Electron capture by {{sup|57}}Co forms an excited state of the {{sup|57}}Fe 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

Isotope masses from:
{{NUBASE 2003}}
Half-life, spin, and isomer data selected from the following sources.
{{NUBASE 2003}}
{{NNDC}}
{{CRC85|chapter=11}}

Category:Cobalt

Cobalt