- Isotopes of cobalt
-
Naturally occurring cobalt (Co) is composed of 1 stable isotope, 59Co. 28 radioisotopes have been characterized with the most stable being 60Co with a half-life of 5.2714 years, 57Co with a half-life of 271.79 days, 56Co with a half-life of 77.27 days, and 58Co with a half-life of 70.86 days. All of the remaining radioactive isotopes have half-lives that are less than 18 hours and the majority of these have half-lives that are less than 1 second. This element also has 11 meta states, all of which have half-lives less than 15 minutes.
The isotopes of cobalt range in atomic weight from 47Co to 75Co. The primary decay mode for isotopes with atomic mass unit values less than that of the most abundant stable isotope, 59Co, is electron capture and the primary mode of decay for those of greater than 59 atomic mass units is beta decay. The primary decay products before 59Co are iron isotopes and the primary products after are nickel isotopes.
Standard atomic mass: 58.933195(5) u
Contents
Use of cobalt radioisotopes in medicine
Cobalt-60 (Co-60 or 60Co) is a radioactive metal that 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 a 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.
Cobalt-57 (Co-57 or 57Co) is a radioactive metal that is used in medical tests; it is used as a radiolabel for vitamin B12 uptake. It is useful for the Schilling test.[1]
Industrial uses for radioactive isotopes
Cobalt-60 (Co-60 or 60Co) is useful as a gamma ray source because it can be produced—in predictable quantity, and high activity—by simply exposing natural cobalt to neutrons in a reactor for a given time. It is used for
- sterilization of medical supplies, and medical waste;
- radiation treatment of foods for sterilization (cold pasteurization);
- industrial radiography (e.g., weld integrity radiographs);
- density measurements (e.g., concrete density measurements); and
- tank fill height switches.
Table
nuclide
symbolZ(p) N(n)
isotopic mass (u)
half-life decay
mode(s)[2][n 1]daughter
isotope(s)[n 2]nuclear
spinrepresentative
isotopic
composition
(mole fraction)range of natural
variation
(mole fraction)excitation energy 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) 5.2713(8) a β- 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-# - ^ Abbreviations:
EC: Electron capture
IT: Isomeric transition - ^ Bold for stable isotopes
Notes
- Values marked # are not purely derived from experimental data, but at least partly from systematic trends. Spins with weak assignment arguments are enclosed in parentheses.
- Uncertainties are given in concise form in parentheses after the corresponding last digits. Uncertainty values denote one standard deviation, except isotopic composition and standard atomic mass from IUPAC which use expanded uncertainties.
References
- ^ L. E. Diaz. "Cobalt-57: Uses". JPNM Physics Isotopes. University of Harvard. http://www.med.harvard.edu/JPNM/physics/isotopes/Co/Co57/uses.html. Retrieved 2010-09-13.
- ^ http://www.nucleonica.net/unc.aspx
- Isotope masses from:
- G. Audi, A. H. Wapstra, C. Thibault, J. Blachot and O. Bersillon (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. http://www.nndc.bnl.gov/amdc/nubase/Nubase2003.pdf.
- Isotopic compositions and standard atomic masses from:
- J. R. de Laeter, J. K. Böhlke, P. De Bièvre, H. Hidaka, H. S. Peiser, K. J. R. Rosman and P. D. P. Taylor (2003). "Atomic weights of the elements. Review 2000 (IUPAC Technical Report)". Pure and Applied Chemistry 75 (6): 683–800. doi:10.1351/pac200375060683. http://www.iupac.org/publications/pac/75/6/0683/pdf/.
- M. E. Wieser (2006). "Atomic weights of the elements 2005 (IUPAC Technical Report)". Pure and Applied Chemistry 78 (11): 2051–2066. doi:10.1351/pac200678112051. http://iupac.org/publications/pac/78/11/2051/pdf/. Lay summary.
- Half-life, spin, and isomer data selected from the following sources. See editing notes on this article's talk page.
- G. Audi, A. H. Wapstra, C. Thibault, J. Blachot and O. Bersillon (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. http://www.nndc.bnl.gov/amdc/nubase/Nubase2003.pdf.
- National Nuclear Data Center. "NuDat 2.1 database". Brookhaven National Laboratory. http://www.nndc.bnl.gov/nudat2/. Retrieved September 2005.
- David R. Lide (ed.), orman E. Holden in CRC Handbook of Chemistry and Physics, 85th Edition, online version. CRC Press. Boca Raton, Florida (2005). Section 11, Table of the Isotopes.
Isotopes of iron Isotopes of cobalt Isotopes of nickel Index to isotope pages · Table of nuclides Categories:- Isotopes of cobalt
- Lists of isotopes by element
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