More Chemistry
All atomic nuclei of the chemical element iron are summarized under iron isotopes; these consist of an atomic nucleus with 26 protons and in the uncharged state of 26 electrons. The difference between the individual iron isotopes lies in the number of neutrons in the nucleus.
The 4 stable isotopes Fe-54, Fe-56, Fe-57 and Fe-58 occur in nature. In addition, 24 unstable radionuclides and several nuclear isomers are known.
| Atomic Mass ma | Quantity | Half-life | Spin | |
| Iron Isotopic mixture | 55,845 u | 100 % | ||
| Isotope 54Fe | 53,939609(3) u | 5,845(105) % | stable | 0+ |
| Isotope 56Fe | 55,934936(3) u | 91,754(106) % | stable | 0+ |
| Isotope 57Fe | 56,935393(3) u | 2,119(29) % | stable | 1/2- |
| Isotope 58Fe | 57,933274(3) u | 0,282(12) % | stable | 0+ |
The iron isotope 57 has particularly good properties in relation to Mössbauer spectroscopy. Co-60 sources are used for the measurements, from which 57Fe nuclei are formed by electron capture with a half-life of 280 days, which in turn gradually decay with loss of energy. The transition from a nuclear spin I = 3/2 to a ground state with the nuclear spin I = 1/2 and the transition energy of 14.4 keV is decisive for Mössbauer spectroscopy. In non-enriched, natural samples, the Fe-57 isotope is only contained at around 2%.
The half-life of the Fe-60 isotope was recalculated in 2009 at 2.6 million years; until then, the value was 1.5 million years [9, 10].
| Isotope Nuclide | E | N | Atomic Mass [Nuclear Mass] {Mass Excess} | Spin I (h/2π) | Parent |
|---|---|---|---|---|---|
| 1 | 2 | 3 | 4 | 5 | 6 |
| Iron-45 | 4526Fe | 19 | 45.01477(43) u [45.0005073 u] {13.75817 MeV} | (3/2+) | 46Co |
| Iron-46 | 4626Fe | 20 | 46.00098(54) u [45.9867173 u] {0.91286 MeV} | 0+ | 47Co |
| Iron-47 | 4726Fe | 21 | 46.99262(54) u [46.9783573 u] {-6.87443 MeV} | (7/2-) | 48Co |
| Iron-48 | 4826Fe | 22 | 47.98068(43) u [47.9664173 u] {-17.99646 MeV} | 0+ | 49Co |
| Iron-49 | 4926Fe | 23 | 48.973429(26) u [48.9591663 u] {-24.75073 MeV} | (7/2-) | |
| Iron-50 | 5026Fe | 24 | 49.962988(9) u [49.9487253 u] {-34.47646 MeV} | 0+ | 50Co |
| Iron-51 | 5126Fe | 25 | 50.956841(10) u [50.9425783 u] {-40.20235 MeV} | 5/2- | 51Co |
| Iron-52 | 5226Fe | 26 | 51.948115(5) u [51.9338523 u] {-48.33057 MeV} | 0+ | 52Co |
| Iron-52m | 52m26Fe | 26 | 51.948115(5) u [51.9338523 u] {-48.33057 MeV} | 12+ | |
| Iron-53 | 5326Fe | 27 | 52.9453056(18) u [52.9310429 u] {-50.94751 MeV} | 7/2- | 53Co |
| Iron-53m | 53m26Fe | 27 | 52.9453056(18) u [52.9310429 u] {-50.94751 MeV} | 19/2- | |
| Iron-54 | 5426Fe | 28 | 53.939609(3) u [53.9253463 u] {-56.25385 MeV} | 0+ | 54Co 54Mn |
| Iron-54m | 54m26Fe | 28 | 53.939609(3) u [53.9253463 u] {-56.25385 MeV} | 10+ | |
| Iron-55 | 5526Fe | 29 | 54.9382912(3) u [54.9240285 u] {-57.48138 MeV} | 3/2- | 55Co |
| Iron-56 | 5626Fe | 30 | 55.934936(3) u [55.9206733 u] {-60.60673 MeV} | 0+ | 56Co 56Mn |
| Iron-57 | 5726Fe | 31 | 56.935393(3) u [56.9211303 u] {-60.18103 MeV} | 1/2- | 57Co 57Mn |
| Iron-58 | 5826Fe | 32 | 57.933274(3) u [57.9190113 u] {-62.15487 MeV} | 0+ | 58Co 58Mn |
| Iron-59 | 5926Fe | 33 | 58.9348735(4) u [58.9206108 u] {-60.66494 MeV} | 3/2- | 59Mn |
| Iron-60 | 6026Fe | 34 | 59.934070(4) u [59.9198073 u] {-61.4134 MeV} | 0+ | 60Mn |
| Iron-61 | 6126Fe | 35 | 60.9367462(28) u [60.9224835 u] {-58.92054 MeV} | (3/2-) | 61Mn |
| Iron-61m | 61m26Fe | 35 | 60.9367462(28) u [60.9224835 u] {-58.92054 MeV} | (9/2+) | |
| Iron-62 | 6226Fe | 36 | 61.936792(3) u [61.9225293 u] {-58.87787 MeV} | 0+ | 62Mn |
| Iron-63 | 6326Fe | 37 | 62.940273(5) u [62.9260103 u] {-55.63534 MeV} | (5/2-) | 63Mn |
| Iron-64 | 6426Fe | 38 | 63.940988(5) u [63.9267253 u] {-54.96932 MeV} | 0+ | 64Mn |
| Iron-65 | 6526Fe | 39 | 64.945015(5) u [64.9307523 u] {-51.2182 MeV} | (1/2-) | 65Mn |
| Iron-65m1 | 65m126Fe | 39 | 64.94538(26) u [64.9311173 u] {-50.8782 MeV} | (3/2+) | |
| Iron-65m2 | 65m226Fe | 39 | 64.94538(26) u [64.9311173 u] {-50.8782 MeV} | (9/2+) | |
| Iron-66 | 6626Fe | 40 | 65.946250(4) u [65.9319873 u] {-50.0678 MeV} | 0+ | 66Mn |
| Iron-67 | 6726Fe | 41 | 66.95104(29) u [66.9367773 u] {-45.60595 MeV} | (5/2+) | 67Mn |
| Iron-67m | 67m26Fe | 41 | 66.95104(29) u [66.9367773 u] {-45.60595 MeV} | (1/2-) | |
| Iron-68 | 6826Fe | 42 | 67.95331(39) u [67.9390473 u] {-43.49145 MeV} | 0+ | 68Mn |
| Iron-69 | 6926Fe | 43 | 68.95810(43) u [68.9438373 u] {-39.0296 MeV} | 1/2-~ | 69Mn |
| Iron-70 | 7026Fe | 44 | 69.96080(43) u [69.9465373 u] {-36.51456 MeV} | 0+ | |
| Iron-71 | 7126Fe | 45 | 70.96626(43) u [70.9519973 u] {-31.42861 MeV} | 7/2+~ | |
| Iron-72 | 7226Fe | 46 | 71.96948(54) u [71.9552173 u] {-28.4292 MeV} | 0+ | |
| Iron-73 | 7326Fe | 47 | 72.97542(54) u [72.9611573 u] {-22.89612 MeV} | ||
| Iron-74 | 7426Fe | 48 | 73.97897(64) u [73.9647073 u] {-19.58932 MeV} | 0+ |
| Isotope | Radioactive Decay | Extern | |||
|---|---|---|---|---|---|
| Half-life | Decay Mode | Probability | Energy | ||
| 7 | 8 | 9 | 10 | 11 | 12 |
| Fe-45 | 1.89 ms | β+ → 45Mn p → 44Mn 2p → 43Cr | AL | ||
| Fe-46 | 13.0(20) ms | β+ → 46Mn EC, p → 45Cr | 21.3 % 78.7(38) % | 13.48(64) MeV | AL |
| Fe-47 | 21.8(7) ms | β+ → 47Mn β+, p → 46Cr β+, 2p → 45Cr | AL | ||
| Fe-48 | 44(7) ms | β+ → 48Mn EC, p → 47Cr | 96.4 % 3.6 % | 11.3(4) MeV | AL |
| Fe-49 | 64.7(3) ms | β+ → 49Mn β+, p → 48Cr | 43.3 % 56.7 % | 12.870(24) MeV | AL |
| Fe-50 | 152.0(6) ms | β+ → 50Mn β+, p → 49Cr | > 99.9 % < 0.01 % | 8.151(8) MeV | AL |
| Fe-51 | 305(2) ms | β+ → 51Mn | 100 % | 8.041(9) MeV | AL |
| Fe-52 | 8.275(8) h | β+ → 52Mn | 100 % | 2.377(5) MeV | AL |
| Fe-52m | 45.9(6) s | β+ → 53Mn Iso → 52Fe | AL | ||
| Fe-53 | 8.51(2) min | β+ → 54Mn | 100 % | 3.7426(17) MeV | AL |
| Fe-53m | 2.54(2) min | Iso → 53Fe | 100 % | AL | |
| Fe-54 | stable | AL | |||
| Fe-54m | 364(7) ns | AL | |||
| Fe-55 | 2.744(9) a | EC → 55Mn | 100 % | 0.2311(4) MeV | AL |
| Fe-56 | stable | AL | |||
| Fe-57 | stable | AL | |||
| Fe-58 | stable | AL | |||
| Fe-59 | 44.490(9) d | β- → 59Co | 100 % | 1.5649(4) MeV | AL |
| Fe-60 | 2.62(4) × 106 a | β- → 60Co | 100 % | 0.237(3) MeV | AL |
| Fe-61 | 5.98(6) min | β- → 61Co | 100 % | 3.9776(27) MeV | AL |
| Fe-61m | 0.238(5) μs | Iso → 61Fe | 100 % | AL | |
| Fe-62 | 68(2) s | β- → 62Co | 100 % | 2.546(19) MeV | AL |
| Fe-63 | 6.1(6) s | β- → 63Co | 100 % | 6.216(19) MeV | AL |
| Fe-64 | 2.0(2) s | β- → 64Co | 100 % | 4.823(21) MeV | AL |
| Fe-65 | 0.81(5) s | β- → 65Co | 100 % | 7.967(6) MeV | AL |
| Fe-65m1 | 0.43(13) μs | Iso → 65Fe | AL | ||
| Fe-65m2 | 1.12(5) s | β- → 65Co | 100 % | 100 % | |
| Fe-66 | 440(60) ms | β- → 66Co | 100 % | 6.341(15) MeV | AL |
| Fe-67 | 0.6 s | β- → 67Co | 100 % | 9.71(27) MeV | AL |
| Fe-67m | 75(21) μs | Iso → 67Fe | 100 % | AL | |
| Fe-68 | 188(4) ms | β- → 68Co β-, n → 67Co | 100 % ? | 8.44(41) MeV 3.76(37) MeV | AL |
| Fe-69 | 110(5) ms | β- → 69Co | 100 % | 11.25(42) MeV | AL |
| Fe-70 | 65(6) ms | β- → 70Co β-, n → 69Co | 100 % ? | 10.12(59) MeV 5.70(42) MeV | AL |
| Fe-71 | 28(5) ms | β- 71Co β-, n 70Co | 100 % | 12.94(61) MeV 7.13(50) MeV | AL |
| Fe-72 | 150 ns | β- 72Co β-, n 71Co | 11.77(64) MeV 7.87(68) MeV | AL | |
| Fe-73 | 12.9(16) ms | β- → 73Co β-, n → 72Co β-, 2n → 71Co | 100 % ? ? | 14.52(64) MeV 9.23(64) MeV | |
| Fe-74 | 8.2 ms | β- → 74Co β-, n → 73Co β-, 2n → 72Co | ? ? ? | 13.23(78) MeV 9.76(72) MeV | |
Notes (related to the columns):
1 - name of the nuclide, isotope.
2 - E: isotope symbol with mass number (superscript; number of nucleons) and Atomic number (subscript; number of protons).
3 - N: number of neutrons.
4 - relative atomic mass of the Iron isotope (isotopic mass including electrons) and the mass of the atomic nucleus in square brackets (nuclear mass, nuclide mass without electrons), each related to 12C = 12.00000 [2]. In addition, the mass excess is given in MeV.
5 - nuclear spin I, unit: h/2π.
6 - source nuclides: Possible, assumed or actual source nuclides (mother nuclides, parent nuclides). If applicable, the corresponding decay modes can be found in the data for the respective starting nuclide.
7 - isotope notation in short form.
8 - decay: half-live of the Iron isotope (a = years; ; d = days; h = hours; min = minutes; s = seconds).
9 - decay mode: type of decay into the respective daughter nuclides with n = neutron emission; p = proton emission; α = alpha decay; β- = beta minus decay with electron emission; EC = electron capture; β+ = positron emission; ε = β+ and/or EC; Iso = isomeric transition; CD = cluster decay; SF = spontaneous decay.
10 - decay probability in percent (%).
11 - decay energy; Particle energy related to decay type.
12 - other information and notes: AL = Adopted Levels (link to external data [1]).
Miscellaneous:
()- Numbers in brackets: uncertainty to represent the spread of the reported value.
~ - Theoretical values or systematic trends.
- unlisted-: Nuclides that have already been mentioned in the literature but for some reason can no longer be found in the current nuclide tables because their discovery e.g. has not confirmed.
| Nuclide quantity 1) spin | Nuclear magnetic moment μ/μN | Gyromagnetic ratio {Quadrupole moment} | Resonant frequency v0 bei 1 T | Relative sensitivity H0 = const. v0 = const. 3) |
|---|---|---|---|---|
| 57Fe 2,119(29) % 1/2- | +0,09064(7) | 0,8661 {+ 0,160} | 1,3816 | 0,00003 0,0324 |
1) Quantity Percentage of natural occurrence.
2) Gyromagnetic ratio: 107 rad T-1 s-1
Quadrupole moment: Q [barn] = [100 fm2]
3) Related to 1H = 1,000.
According to the Radiation Protection Ordinance (StrlSchV 2018, Germany), the following values (columns 1 to 7) apply to the handling of Iron radionuclides:
| Nuclide | Limit Value | HASS limit | SC | Daughter Nuclides | Half-life | |
|---|---|---|---|---|---|---|
| Fe-52+ | 106 Bq | 10 Bq/g | 0,02 TBq | 100 Bq cm-2 | 8.3 h | |
| Fe-55 | 106 Bq | 1000 Bq/g | 800 TBq | 100 Bq cm-2 | 2.7 a | |
| Fe-59 | 106 Bq | 1 Bq/g | 0,06 TBq | 1 Bq cm-2 | 44.5 d | |
| Fe-60+ | 105 Bq | 10 Bq/g | 0,06 TBq | Co-60m | 1500000 a | |
(HASS = High-Activity Sealed Radioactive Sources; SC = surface contamination)
Properties of the Iron nucleides
[1] - NuDat: National Nuclear Data Center, Brookhaven National Laboratory, based on ENSDF and the Nuclear Wallet Cards.
[2] - G. Audi et. al.: The NUBASE evaluation of nuclear and decay properties. Nuclear Physics, (2003), DOI 10.1016/j.nuclphysa.2003.11.001.
[3] - Live Chart of Nuclides. Nuclear structure and decay data.
Iron: NMR properties - 57Fe-NMR
[4] - N. J. Stone: Table of nuclear magnetic dipole and electric quadrupole moments. Atomic Data and Nuclear Data Tables, (2005), DOI 10.1016/j.adt.2005.04.001.
[5] - Pekka Pyykkö: Year-2008 nuclear quadrupole moments. Molecular Physics, (2008), DOI 10.1080/00268970802018367.
[6] - Pekka Pyykkö: Year-2017 nuclear quadrupole moments. Molecular Physics, (2018), DOI 10.1080/00268976.2018.1426131.
[7] - N. J. Stone: Table of recommended nuclear magnetic dipole moments. IAEA, (2019).
More sources:
[8] - Isotopic abundances, atomic weights and isotopic masses: see respective keyword.
[9] - NN:
Eisen-60 Isotop: Halbwertszeit von Eisen-60 überrascht Forscher.
In: Internetchemie News, (2009).
[10] - Rugel et al.:
New Measurement of the 60Fe Half-Life.
In: Physical Review Letters, (2009), DOI 10.1103/PhysRevLett.103.072502.
Last update: 2022-12-12
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