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Isotopes of Iron

List, data and properties of all known isotopes of Iron as well as radioactive decay products and intermediate products.

 

Iron isotopes

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.

 

Naturally Occurring Iron Isotopes

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 maQuantityHalf-lifeSpin
Iron
Isotopic mixture
55,845 u100 %
Isotope 54Fe53,939609(3) u5,845(105) %stable0+
Isotope 56Fe55,934936(3) u91,754(106) %stable0+
Isotope 57Fe56,935393(3) u2,119(29) %stable1/2-
Isotope 58Fe57,933274(3) u0,282(12) %stable0+

 

 

Iron-57

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%.

 

Iron-60

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 Table: Iron

 

Atomic Properties

Isotope
Nuclide
ZANNameAtomic Mass
[Nuclear Mass]
{Mass Excess}
Spin I
(h/2π)
μParent
123456789
45Fe264519Iron-4545.01477(43) u
[45.0005073 u]
{13.75817 MeV}
(3/2+)46Co
46Fe264620Iron-4646.00098(54) u
[45.9867173 u]
{0.91286 MeV}
0+47Co
47Fe264721Iron-4746.99262(54) u
[46.9783573 u]
{-6.87443 MeV}
(7/2-)48Co
48Fe264822Iron-4847.98068(43) u
[47.9664173 u]
{-17.99646 MeV}
0+49Co
49Fe264923Iron-4948.973429(26) u
[48.9591663 u]
{-24.75073 MeV}
(7/2-)
50Fe265024Iron-5049.962988(9) u
[49.9487253 u]
{-34.47646 MeV}
0+50Co
51Fe265125Iron-5150.956841(10) u
[50.9425783 u]
{-40.20235 MeV}
5/2-51Co
52Fe265226Iron-5251.948115(5) u
[51.9338523 u]
{-48.33057 MeV}
0+52Co
52mFe265226Iron-52m51.948115(5) u
[51.9338523 u]
{-48.33057 MeV}
12+
53Fe265327Iron-5352.9453056(18) u
[52.9310429 u]
{-50.94751 MeV}
7/2--0.65(1)53Co
53mFe265327Iron-53m52.9453056(18) u
[52.9310429 u]
{-50.94751 MeV}
19/2-
54Fe265428Iron-5453.939609(3) u
[53.9253463 u]
{-56.25385 MeV}
0+54Co
54Mn
54mFe265428Iron-54m53.939609(3) u
[53.9253463 u]
{-56.25385 MeV}
10++7.281(10)
55Fe265529Iron-55549382913(4) u
[549382912.98574 u]
{511746835929.85 MeV}
3/2-55Co
56Fe265630Iron-5655.934936(3) u
[55.9206733 u]
{-60.60673 MeV}
0+56Co
56Mn
57Fe265731Iron-5756.935393(3) u
[56.9211303 u]
{-60.18103 MeV}
1/2-+0.09064(7)57Co
57Mn
58Fe265832Iron-5857.933274(3) u
[57.9190113 u]
{-62.15487 MeV}
0+58Co
58Mn
59Fe265933Iron-5958.9348736(4) u
[58.9206109 u]
{-60.66485 MeV}
3/2--0.3358(4)59Mn
60Fe266034Iron-6059.934070(4) u
[59.9198073 u]
{-61.4134 MeV}
0+60Mn
61Fe266135Iron-6160.9367462(28) u
[60.9224835 u]
{-58.92054 MeV}
(3/2-)61Mn
61mFe266135Iron-61m60.9367462(28) u
[60.9224835 u]
{-58.92054 MeV}
(9/2+)-1.031(9)
62Fe266236Iron-6261.936792(3) u
[61.9225293 u]
{-58.87787 MeV}
0+62Mn
63Fe266337Iron-6362.940273(5) u
[62.9260103 u]
{-55.63534 MeV}
(5/2-)63Mn
64Fe266438Iron-6463.940988(5) u
[63.9267253 u]
{-54.96932 MeV}
0+64Mn
65Fe266539Iron-6564.945015(5) u
[64.9307523 u]
{-51.2182 MeV}
(1/2-)65Mn
65m1Fe266539Iron-65m164.94538(26) u
[64.9311173 u]
{-50.8782 MeV}
(3/2+)
65m2Fe266539Iron-65m264.94538(26) u
[64.9311173 u]
{-50.8782 MeV}
(9/2+)
66Fe266640Iron-6665.946250(4) u
[65.9319873 u]
{-50.0678 MeV}
0+66Mn
67Fe266741Iron-6766.95104(29) u
[66.9367773 u]
{-45.60595 MeV}
(5/2+)67Mn
67mFe266741Iron-67m66.95104(29) u
[66.9367773 u]
{-45.60595 MeV}
(1/2-)
68Fe266842Iron-6867.95331(39) u
[67.9390473 u]
{-43.49145 MeV}
0+68Mn
69Fe266943Iron-6968.95810(43) u
[68.9438373 u]
{-39.0296 MeV}
1/2-~69Mn
70Fe267044Iron-7069.96080(43) u
[69.9465373 u]
{-36.51456 MeV}
0+
71Fe267145Iron-7170.96626(43) u
[70.9519973 u]
{-31.42861 MeV}
7/2+~
72Fe267246Iron-7271.96948(54) u
[71.9552173 u]
{-28.4292 MeV}
0+
73Fe267347Iron-7372.97542(54) u
[72.9611573 u]
{-22.89612 MeV}
74Fe267448Iron-7473.97897(64) u
[73.9647073 u]
{-19.58932 MeV}
0+

 

Radioactive Decay Properties

IsotopeRadioactive DecayAEExtern
Half-lifeDecay ModeProbabilityEnergy
1101112131415
Fe-451.89 msβ+45Mn
p → 44Mn
2p → 43Cr




AL
Fe-4613.0(20) msβ+46Mn
EC, p → 45Cr
21.3 %
78.7(38) %
13.48(64) MeV
AL
Fe-4721.8(7) msβ+47Mn
β+, p → 46Cr
β+, 2p → 45Cr




AL
Fe-4844(7) msβ+48Mn
EC, p → 47Cr
96.4 %
3.6 %
11.3(4) MeV
AL
Fe-4964.7(3) msβ+49Mn
β+, p → 48Cr
43.3 %
56.7 %
12.870(24) MeV
AL
Fe-50152.0(6) msβ+50Mn
β+, p → 49Cr
> 99.9 %
< 0.01 %
8.151(8) MeV
AL
Fe-51305(2) msβ+51Mn100 %8.041(9) MeVAL
Fe-528.275(8) hβ+52Mn100 %2.377(5) MeVAL
Fe-52m45.9(6) sβ+53Mn
Iso → 52Fe


6958.0(4) keVAL
Fe-538.51(2) minβ+54Mn100 %3.7426(17) MeVAL
Fe-53m2.54(2) minIso → 53Fe100 %3040.4(3) keVAL
Fe-54stableAL
Fe-54m364(7) ns6527.1(11) keVAL
Fe-552.744(9) aEC → 55Mn100 %0.2311(5) MeVAL
Fe-56stableAL
Fe-57stableAL
Fe-58stableAL
Fe-5944.490(9) dβ-59Co100 %1.5649(4) MeVAL
Fe-602.62(4) × 106 aβ-60Co100 %0.237(3) MeVAL
Fe-615.98(6) minβ-61Co100 %3.9776(27) MeVAL
Fe-61m0.238(5) μsIso → 61Fe100 %861.67(11) keVAL
Fe-6268(2) sβ-62Co100 %2.546(19) MeVAL
Fe-636.1(6) sβ-63Co100 %6.216(19) MeVAL
Fe-642.0(2) sβ-64Co100 %4.823(21) MeVAL
Fe-650.81(5) sβ-65Co100 %7.967(6) MeVAL
Fe-65m10.43(13) μsIso → 65Fe364 keVAL
Fe-65m21.12(5) sβ-65Co100 %100 %402(5) keV
Fe-66440(60) msβ-66Co100 %6.341(15) MeVAL
Fe-670.6 sβ-67Co100 %9.71(27) MeVAL
Fe-67m75(21) μsIso → 67Fe100 %387 keVAL
Fe-68188(4) msβ-68Co
β-, n → 67Co
100 %
?
8.44(41) MeV
3.76(37) MeV
AL
Fe-69110(5) msβ-69Co100 %11.25(42) MeVAL
Fe-7065(6) msβ-70Co
β-, n → 69Co
100 %
?
10.12(59) MeV
5.70(42) MeV
AL
Fe-7128(5) msβ- 71Co
β-, n 70Co
100 %
12.94(61) MeV
7.13(50) MeV
AL
Fe-72150 nsβ- 72Co
β-, n 71Co

11.77(64) MeV
7.87(68) MeV
AL
Fe-7312.9(16) msβ-73Co
β-, n → 72Co
β-, 2n → 71Co
100 %
?
?
14.52(64) MeV
9.23(64) MeV
Fe-748.2 msβ-74Co
β-, n → 73Co
β-, 2n → 72Co
?
?
?
13.23(78) MeV
9.76(72) MeV

 

Notes (related to the columns):

1 - nuclide, isotope symbol.
2 - Z = number of protons (atomic number).
3 - Mass number A.
4 - N = number of neutrons.
5 - Identification of the Iron isotope.
6 - 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.
7 - Nuclear spin I, unit: h/2π.
8 - Nuclear magnetic moment μmag.
9 - 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.
10 - Decay: Half-live of the Iron isotope (a = years; ; d = days; h = hours; min = minutes; s = seconds).
11 - Decay: 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.
12 - Decay percentage in percent (%).
13 - Decay energy; Particle energy related to decay type.
14 - AE = Excitation energy for metastable nuclei.
15 - 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.

 

NMR active Iron nuclides

Nuclide
quantity 1)
spin
Nuclear magnetic
moment
μ/μN
Gyromagnetic
ratio
107 rad T-1 s-1
Quadrupole
moment
Q fm-2
Resonant
frequency
v0 bei 1 T
Relative
sensitivity
H0 = const.
v0 = const. 2)
57Fe
2,119(29) %
1/2-
+0,09064(7)0,8661+ 16,01,38160,00003
0,0324

1) Quantity Percentage of natural occurrence.

2) Related to 1H = 1,000.

 

Radiation Protection

According to the Radiation Protection Ordinance (StrlSchV 2018, Germany), the following values (columns 1 to 7) apply to the handling of Iron radionuclides:

NuclideLimit ValueHASS limitSCDaughter NuclidesHalf-life
Fe-52+106 Bq10 Bq/g0,02 TBq100 Bq cm-28.3 h
Fe-55106 Bq1000 Bq/g800 TBq100 Bq cm-22.7 a
Fe-59106 Bq1 Bq/g0,06 TBq1 Bq cm-244.5 d
Fe-60+105 Bq10 Bq/g0,06 TBqCo-60m1500000 a

(HASS = High-Activity Sealed Radioactive Sources; SC = surface contamination)

 

Literature Sources and References

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), DOI https://www.internetchemie.info/news/2009/aug09/eisen-60-halbwertszeit.php.

[10] - Rugel et al.:
New Measurement of the 60Fe Half-Life.
In: Physical Review Letters, (2009), DOI 10.1103/PhysRevLett.103.072502.

 


Category: Isotopes

Last update: 05.07.2020



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