Isotopes of iron
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Standard atomic weight Ar°(Fe) | ||||||||||||||||||||||||||||||||||||||||||||||
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Naturally occurring iron (26Fe) consists of four stable isotopes: 5.845% of 54Fe (possibly radioactive with a half-life over 4.4×1020 years),[4] 91.754% of 56Fe, 2.119% of 57Fe and 0.286% of 58Fe. There are 24 known radioactive isotopes, the most stable of which are 60Fe (half-life 2.6 million years) and 55Fe (half-life 2.7 years).
Much of the past work on measuring the isotopic composition of Fe has centered on determining 60Fe variations due to processes accompanying nucleosynthesis (i.e., meteorite studies) and ore formation. In the last decade however, advances in mass spectrometry technology have allowed the detection and quantification of minute, naturally occurring variations in the ratios of the stable isotopes of iron. Much of this work has been driven by the Earth and planetary science communities, although applications to biological and industrial systems are beginning to emerge.[5]
List of isotopes
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 | Normal proportion | Range of variation | |||||||||||||||||
45Fe | 26 | 19 | 45.01458(24)# | 1.89(49) ms | β+ (30%) | 45Mn | 3/2+# | ||||||||||||
2p (70%) | 43Cr | ||||||||||||||||||
46Fe | 26 | 20 | 46.00081(38)# | 9(4) ms [12(+4-3) ms] |
β+ (>99.9%) | 46Mn | 0+ | ||||||||||||
β+, p (<.1%) | 45Cr | ||||||||||||||||||
47Fe | 26 | 21 | 46.99289(28)# | 21.8(7) ms | β+ (>99.9%) | 47Mn | 7/2−# | ||||||||||||
β+, p (<.1%) | 46Cr | ||||||||||||||||||
48Fe | 26 | 22 | 47.98050(8)# | 44(7) ms | β+ (96.41%) | 48Mn | 0+ | ||||||||||||
β+, p (3.59%) | 47Cr | ||||||||||||||||||
49Fe | 26 | 23 | 48.97361(16)# | 70(3) ms | β+, p (52%) | 48Cr | (7/2−) | ||||||||||||
β+ (48%) | 49Mn | ||||||||||||||||||
50Fe | 26 | 24 | 49.96299(6) | 155(11) ms | β+ (>99.9%) | 50Mn | 0+ | ||||||||||||
β+, p (<.1%) | 49Cr | ||||||||||||||||||
51Fe | 26 | 25 | 50.956820(16) | 305(5) ms | β+ | 51Mn | 5/2− | ||||||||||||
52Fe | 26 | 26 | 51.948114(7) | 8.275(8) h | β+ | 52mMn | 0+ | ||||||||||||
52mFe | 6.81(13) MeV | 45.9(6) s | β+ | 52Mn | (12+)# | ||||||||||||||
53Fe | 26 | 27 | 52.9453079(19) | 8.51(2) min | β+ | 53Mn | 7/2− | ||||||||||||
53mFe | 3040.4(3) keV | 2.526(24) min | IT | 53Fe | 19/2− | ||||||||||||||
54Fe | 26 | 28 | 53.9396090(5) | Observationally Stable[n 8] | 0+ | 0.05845(35) | 0.05837–0.05861 | ||||||||||||
54mFe | 6526.9(6) keV | 364(7) ns | 10+ | ||||||||||||||||
55Fe | 26 | 29 | 54.9382934(7) | 2.737(11) y | EC | 55Mn | 3/2− | ||||||||||||
56Fe[n 9] | 26 | 30 | 55.9349363(5) | 101014 y [hyperstable] | 0+ | 0.91754(36) | 0.91742–0.91760 | ||||||||||||
57Fe | 26 | 31 | 56.9353928(5) | Stable | 1/2− | 0.02119(10) | 0.02116–0.02121 | ||||||||||||
58Fe | 26 | 32 | 57.9332744(5) | Stable | 0+ | 0.00282(4) | 0.00281–0.00282 | ||||||||||||
59Fe | 26 | 33 | 58.9348755(8) | 44.495(9) d | β− | 59Co | 3/2− | ||||||||||||
60Fe | 26 | 34 | 59.934072(4) | 2.6×106 y | β− | 60Co | 0+ | trace | |||||||||||
61Fe | 26 | 35 | 60.936745(21) | 5.98(6) min | β− | 61Co | 3/2−,5/2− | ||||||||||||
61mFe | 861(3) keV | 250(10) ns | 9/2+# | ||||||||||||||||
62Fe | 26 | 36 | 61.936767(16) | 68(2) s | β− | 62Co | 0+ | ||||||||||||
63Fe | 26 | 37 | 62.94037(18) | 6.1(6) s | β− | 63Co | (5/2)− | ||||||||||||
64Fe | 26 | 38 | 63.9412(3) | 2.0(2) s | β− | 64Co | 0+ | ||||||||||||
65Fe | 26 | 39 | 64.94538(26) | 1.3(3) s | β− | 65Co | 1/2−# | ||||||||||||
65mFe | 364(3) keV | 430(130) ns | (5/2−) | ||||||||||||||||
66Fe | 26 | 40 | 65.94678(32) | 440(40) ms | β− (>99.9%) | 66Co | 0+ | ||||||||||||
β−, n (<.1%) | 65Co | ||||||||||||||||||
67Fe | 26 | 41 | 66.95095(45) | 394(9) ms | β− (>99.9%) | 67Co | 1/2−# | ||||||||||||
β−, n (<.1%) | 66Co | ||||||||||||||||||
67mFe | 367(3) keV | 64(17) µs | (5/2−) | ||||||||||||||||
68Fe | 26 | 42 | 67.95370(75) | 187(6) ms | β− (>99.9%) | 68Co | 0+ | ||||||||||||
β−, n | 67Co | ||||||||||||||||||
69Fe | 26 | 43 | 68.95878(54)# | 109(9) ms | β− (>99.9%) | 69Co | 1/2−# | ||||||||||||
β−, n (<.1%) | 68Co | ||||||||||||||||||
70Fe | 26 | 44 | 69.96146(64)# | 94(17) ms | 0+ | ||||||||||||||
71Fe | 26 | 45 | 70.96672(86)# | 30# ms [>300 ns] |
7/2+# | ||||||||||||||
72Fe | 26 | 46 | 71.96962(86)# | 10# ms [>300 ns] |
0+ | ||||||||||||||
This table header & footer: |
- ^ mFe – Excited nuclear isomer.
- ^ ( ) – Uncertainty (1σ) is given in concise form in parentheses after the corresponding last digits.
- ^ # – Atomic mass marked #: value and uncertainty derived not from purely experimental data, but at least partly from trends from the Mass Surface (TMS).
- ^ a b # – Values marked # are not purely derived from experimental data, but at least partly from trends of neighboring nuclides (TNN).
- ^
Modes of decay:
EC: Electron capture IT: Isomeric transition n: Neutron emission p: Proton emission - ^ Bold symbol as daughter – Daughter product is stable.
- ^ ( ) spin value – Indicates spin with weak assignment arguments.
- ^ Believed to decay by β+β+ to 54Cr with a half-life of over 4.4×1020 a[4]
- ^ Lowest mass per nucleon of all nuclides; End product of stellar nucleosynthesis
- Atomic masses of the stable nuclides (54Fe, 56Fe, 57Fe, and 58Fe) are given by the AME2012 atomic mass evaluation. The one standard deviation errors are given in parentheses after the corresponding last digits.[6]
Iron-54
54Fe is observationally stable, but theoretically can decay to 54Cr, with a half-life of more than 4.4×1020 years via double electron capture (εε).[4]
Iron-56
The isotope 56Fe is the isotope with the lowest mass per nucleon, 930.412 MeV/c2, though not the isotope with the highest nuclear binding energy per nucleon, which is nickel-62.[7] However, because of the details of how nucleosynthesis works, 56Fe is a more common endpoint of fusion chains inside extremely massive stars and is therefore more common in the universe, relative to other metals, including 62Ni, 58Fe and 60Ni, all of which have a very high binding energy.
Iron-57
The isotope 57Fe is widely used in Mössbauer spectroscopy and the related nuclear resonance vibrational spectroscopy due to the low natural variation in energy of the 14.4 keV nuclear transition.[8] The transition was famously used to make the first definitive measurement of gravitational redshift, in the 1960 Pound–Rebka experiment.[9]
Iron-58
Iron-58 is a stable isotope of iron. It can be used to combat anemia and low iron absorption, to metabolically track iron-controlling human genes, and for tracing elements in nature.[10][11] Iron-58 is also an assisting reagent in the synthesis of superheavy elements.[11]
Iron-60
Iron-60 is an iron isotope with a half-life of 2.6 million years,[12][13] but was thought until 2009 to have a half-life of 1.5 million years. It undergoes beta decay to cobalt-60, which then decays with a half-life of about 5 years to stable nickel-60. Traces of iron-60 have been found in lunar samples.
In phases of the meteorites Semarkona and Chervony Kut, a correlation between the concentration of 60Ni, the granddaughter isotope of 60Fe, and the abundance of the stable iron isotopes could be found, which is evidence for the existence of 60Fe at the time of formation of the Solar System. Possibly the energy released by the decay of 60Fe contributed, together with the energy released by decay of the radionuclide 26Al, to the remelting and differentiation of asteroids after their formation 4.6 billion years ago. The abundance of 60Ni present in extraterrestrial material may also provide further insight into the origin of the Solar System and its early history.
Iron-60 found in fossilised bacteria in sea floor sediments suggest there was a supernova in the vicinity of the Solar System approximately 2 million years ago.[14][15] Iron-60 is also found in sediments from 8 million years ago.[16]
In 2019, researchers found interstellar 60Fe in Antarctica, which they relate to the Local Interstellar Cloud.[17]
References
- ^ 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.
- ^ "Standard Atomic Weights: Iron". CIAAW. 1993.
- ^ 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.
- ^ a b c Bikit, I.; Krmar, M.; Slivka, J.; Vesković, M.; Čonkić, Lj.; Aničin, I. (1998). "New results on the double β decay of iron". Physical Review C. 58 (4): 2566–2567. Bibcode:1998PhRvC..58.2566B. doi:10.1103/PhysRevC.58.2566.
- ^ N. Dauphas; O. Rouxel (2006). "Mass spectrometry and natural variations of iron isotopes". Mass Spectrometry Reviews. 25 (4): 515–550. Bibcode:2006MSRv...25..515D. doi:10.1002/mas.20078. PMID 16463281.
- ^ Wang, M.; Audi, G.; Wapstra, A.H.; Kondev, F.G.; MacCormick, M.; Xu, X.; Pfeiffer, B. (2012). "The Ame2012 atomic mass evaluation". Chinese Physics C. 36 (12): 1603–2014. Bibcode:2012ChPhC..36....3M. doi:10.1088/1674-1137/36/12/003. hdl:11858/00-001M-0000-0010-23E8-5. S2CID 250839471.
- ^ Fewell, M. P. (1995). "The atomic nuclide with the highest mean binding energy". American Journal of Physics. 63 (7): 653. Bibcode:1995AmJPh..63..653F. doi:10.1119/1.17828.
- ^ R. Nave. "Mossbauer Effect in Iron-57". HyperPhysics. Georgia State University. Retrieved 2009-10-13.
- ^ Pound, R. V.; Rebka Jr. G. A. (April 1, 1960). "Apparent weight of photons". Physical Review Letters. 4 (7): 337–341. Bibcode:1960PhRvL...4..337P. doi:10.1103/PhysRevLett.4.337.
- ^ "Iron-58 Metal Isotope". American Elements. Retrieved 2023-06-28.
- ^ a b Vasiliev, Petr. "Iron-58, Iron-58 Isotope, Enriched Iron-58, Iron-58 Metal". www.buyisotope.com. Retrieved 2023-06-28.
- ^ Rugel, G.; Faestermann, T.; Knie, K.; Korschinek, G.; Poutivtsev, M.; Schumann, D.; Kivel, N.; Günther-Leopold, I.; Weinreich, R.; Wohlmuther, M. (2009). "New Measurement of the 60Fe Half-Life". Physical Review Letters. 103 (7): 72502. Bibcode:2009PhRvL.103g2502R. doi:10.1103/PhysRevLett.103.072502. PMID 19792637.
- ^ "Eisen mit langem Atem". scienceticker. 27 August 2009. Archived from the original on 3 February 2018. Retrieved 22 May 2010.
- ^ Belinda Smith (Aug 9, 2016). "Ancient bacteria store signs of supernova smattering". Cosmos.
- ^ Peter Ludwig; et al. (Aug 16, 2016). "Time-resolved 2-million-year-old supernova activity discovered in Earth's microfossil record". PNAS. 113 (33): 9232–9237. arXiv:1710.09573. Bibcode:2016PNAS..113.9232L. doi:10.1073/pnas.1601040113. PMC 4995991. PMID 27503888.
- ^ Colin Barras (Oct 14, 2017). "Fires may have given our evolution a kick-start". New Scientist. 236 (3147): 7. Bibcode:2017NewSc.236....7B. doi:10.1016/S0262-4079(17)31997-8.
- ^ Koll, Dominik; et., al. (2019). "Interstellar 60Fe in Antarctica". Physical Review Letters. 123 (7): 072701. Bibcode:2019PhRvL.123g2701K. doi:10.1103/PhysRevLett.123.072701. hdl:1885/298253. PMID 31491090. S2CID 201868513.
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:
- 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.
Further reading
- J. M. Nielsen (1960). The Radiochemistry of Iron (PDF). National Academy of Sciences/National Research Council.