Isotopes of cobalt

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Isotopes of cobalt  (27Co)
Main isotopes [1] Decay
Isotope abun­dance half-life (t1/2) mode pro­duct
56Co synth 77.24 d β+ 56Fe
57Cosynth271.81 d ε 57Fe
58Cosynth70.84 dβ+ 58Fe
59Co100% stable
60Co trace 5.2714 y β 60Ni
Standard atomic weight Ar°(Co)

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 (271.81 days), 56Co (77.24 days), and 58Co (70.84 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 8.85 hours.

Contents

The isotopes of cobalt range in atomic weight from 50Co to 78Co. The main decay mode for isotopes with atomic mass less than that of the stable isotope, 59Co, is electron capture to iron isotopes, and the main mode of decay for those with greater mass is beta decay to nickel isotopes.

List of isotopes


Nuclide
[n 1]
Z N Isotopic mass (Da) [4]
[n 2] [n 3]
Half-life [1]
[n 4]
Decay
mode
[1]
[n 5]
Daughter
isotope

[n 6]
Spin and
parity [1]
[n 7] [n 4]
Isotopic
abundance
Excitation energy [n 4]
48Co2721
50Co272349.98112(14)38.8(2) msβ+, p (70.5%)49Mn(6+)
β+ (29.5%)50Fe
β+, 2p?48Cr
51Co272450.970647(52)68.8(19) msβ+ (96.2%)51Fe7/2−
β+, p (<3.8%)50Mn
52Co272551.9631302(57)111.7(21) msβ+52Fe6+
β+, p?51Mn
52mCo376(9) keV102(5) msβ+52Fe2+
IT?52Co
β+, p?51Mn
53Co272652.9542033(19)244.6(28) msβ+53Fe7/2−#
53mCo3174.3(9) keV250(10) msβ+? (~98.5%)53Fe(19/2−)
p (~1.5%)52Fe
54Co272753.94845908(38)193.27(6) msβ+54Fe0+
54mCo197.57(10) keV1.48(2) minβ+54Fe7+
55Co272854.94199642(43)17.53(3) hβ+55Fe7/2−
56Co272955.93983803(51)77.236(26) dβ+56Fe4+
57Co273056.93628982(55)271.811(32) d EC 57Fe7/2−
58Co273157.9357513(12)70.844(20) dEC (85.21%)58Fe2+
β+ (14.79%)58Fe
58m1Co24.95(6) keV8.853(23) hIT (99.9988%)58Co5+
EC (0.00120%)58Fe
58m2Co53.15(7) keV10.5(3) μsIT58Co4+
59Co273258.93319352(43)Stable7/2−1.0000
60Co 273359.93381554(43)5.2714(6) yβ60Ni5+
60mCo58.59(1) keV10.467(6) minIT (99.75%)60Co2+
β (0.25%)60Ni
61Co273460.93247603(90)1.649(5) hβ61Ni7/2−
62Co273561.934058(20)1.54(10) minβ62Ni(2)+
62mCo22(5) keV13.86(9) minβ (>99.5%)62Ni(5)+
IT (<0.5%)62Co
63Co273662.933600(20)26.9(4) sβ63Ni7/2−
64Co273763.935810(21)300(30) msβ64Ni1+
64mCo107(20) keV300# msβ?64Ni5+#
IT?64Co
65Co273864.9364621(22)1.16(3) sβ65Ni(7/2)−
66Co273965.939443(15)194(17) msβ66Ni(1+)
β, n?65Ni
66m1Co175.1(3) keV824(22) nsIT66Co(3+)
66m2Co642(5) keV>100 μsIT66Co(8−)
67Co274066.9406096(69)329(28) msβ67Ni(7/2−)
β, n?66Ni
67mCo491.55(11) keV496(33) msIT (>80%)67Co(1/2−)
β67Ni
68Co274167.9445594(41)200(20) msβ68Ni(7−)
β, n?67Ni
68m1Co [n 8] 150(150)# keV1.6(3) sβ68Ni(2−)
β, n (>2.6%)67Ni
68m2Co195(150)# keV101(10) nsIT68Co(1)
69Co274268.945909(92)180(20) msβ69Ni(7/2−)
β, n?68Ni
69mCo [n 8] 170(90) keV750(250) msβ69Ni1/2−#
70Co274369.950053(12)508(7) msβ70Ni(1+)
β, n?69Ni
β, 2n?68Ni
70mCo [n 8] 200(200)# keV112(7) msβ70Ni(7−)
IT?70Co
β, n?69Ni
β, 2n?68Ni
71Co274470.95237(50)80(3) msβ (97%)71Ni(7/2−)
β, n (3%)70Ni
72Co274571.95674(32)#51.5(3) msβ (<96%)72Ni(6−,7−)
β, n (>4%)71Ni
β, 2n?70Ni
72mCo [n 8] 200(200)# keV47.8(5) msβ72Ni(0+,1+)
73Co274672.95924(32)#42.0(8) msβ (94%)73Ni(7/2−)
β, n (6%)72Ni
β, 2n?71Ni
74Co274773.96399(43)#31.3(13) msβ (82%)74Ni7−#
β, n (18%)73Ni
β, 2n?72Ni
75Co274874.96719(43)#26.5(12) msβ (>84%)75Ni7/2−#
β, n (<16%)74Ni
β, 2n?73Ni
76Co274975.97245(54)#23(6) msβ76Ni(8−)
β, n?75Ni
β, 2n?74Ni
76m1Co [n 8] 100(100)# keV16(4) msβ76Ni(1−)
76m2Co740(100)# keV2.99(27) μsIT76Co(3+)
77Co275076.97648(64)#15(6) msβ77Ni7/2−#
β, n?76Ni
β, 2n?75Ni
β, 3n?74Ni
78Co275177.983 55(75)#11# ms
[>410 ns]
β?78Ni
This table header & footer:
  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. 1 2 3 #  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
    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.
  8. 1 2 3 4 5 Order of ground state and isomer is uncertain.

Stellar nucleosynthesis of cobalt-56

One of the terminal nuclear reactions in stars prior to supernova produces 56Ni. 56Ni then decays to 56Co, which then decays to 56Fe. These decays 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 68.6 days to 69.6 days. [5] The rate at which the luminosity decreased closely matched that expected of exponential decay of 56Co.

Cobalt-57

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]

57Co is used as a source[ clarification needed ] 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.

Cobalt-60

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.[ citation needed ] 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 more usual.

Cobalt-60 (60Co) is useful as an industrial gamma ray source also: uses for industrial cobalt include

See also

Daughter products other than cobalt

References

  1. 1 2 3 4 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. 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.
  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. doi:10.1086/115939 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. "Beneficial Uses of Cobalt-60". INTERNATIONAL IRRADIATION ASSOCIATION. Retrieved 2022-12-09.