Iron-57

Natural iron (Fe) consists of four stable isotopes: 5.845% Fe (possibly radioactive with half-life > years), 91.754% Fe, 2.119% Fe and 0.286% Fe. There are 28 known radioisotopes and 8 nuclear isomers, the most stable of which are Fe (half-life 2.6 million years) and Fe (half-life 2.7 years).

Much of the past work on measuring the isotopic composition of iron has centered on determining Fe 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, though applications to biological and industrial systems are beginning to emerge.

List of isotopes

, -id=Iron-45
, rowspan=4, ⁴⁵Fe
, rowspan=4 style="text-align:right" , 26
, rowspan=4 style="text-align:right" , 19
, rowspan=4, 45.01547(30)#
, rowspan=4, 2.5(2) ms
, 2 p (70%)
, ⁴³Cr
, rowspan=4, 3/2+#
, rowspan=4,
, rowspan=4,
, -
, β⁺, p (18.9%)
, ⁴⁴Cr
, -
, β⁺, 2p (7.8%)
, ⁴³V
, -
, β⁺ (3.3%)
, ⁴⁵Mn
, -id=Iron-46
, rowspan=3, ⁴⁶Fe
, rowspan=3 style="text-align:right" , 26
, rowspan=3 style="text-align:right" , 20
, rowspan=3, 46.00130(32)#
, rowspan=3, 13.0(20) ms
, β⁺, p (78.7%)
, ⁴⁵Cr
, rowspan=3, 0+
, rowspan=3,
, rowspan=3,
, -
, β⁺ (21.3%)
, ⁴⁶Mn
, -
, β⁺, 2p?
, ⁴⁴V
, -id=Iron-47
, rowspan=2, ⁴⁷Fe
, rowspan=2 style="text-align:right" , 26
, rowspan=2 style="text-align:right" , 21
, rowspan=2, 46.99235(54)#
, rowspan=2, 21.9(2) ms
, β⁺, p (88.4%)
, ⁴⁶Cr
, rowspan=2, 7/2−#
, rowspan=2,
, rowspan=2,
, -
, β⁺ (11.6%)
, ⁴⁷Mn
, -id=Iron-48
, rowspan=2, ⁴⁸Fe
, rowspan=2 style="text-align:right" , 26
, rowspan=2 style="text-align:right" , 22
, rowspan=2, 47.980667(99)
, rowspan=2, 45.3(6) ms
, β⁺ (84.7%)
, ⁴⁸Mn
, rowspan=2, 0+
, rowspan=2,
, rowspan=2,
, -
, β⁺, p (15.3%)
, ⁴⁷Cr
, -id=Iron-49
, rowspan=2, ⁴⁹Fe
, rowspan=2 style="text-align:right" , 26
, rowspan=2 style="text-align:right" , 23
, rowspan=2, 48.973429(26)
, rowspan=2, 64.7(3) ms
, β⁺, p (56.7%)
, ⁴⁸Cr
, rowspan=2, (7/2−)
, rowspan=2,
, rowspan=2,
, -
, β⁺ (43.3%)
, ⁴⁹Mn
, -id=Iron-50
, rowspan=2, ⁵⁰Fe
, rowspan=2 style="text-align:right" , 26
, rowspan=2 style="text-align:right" , 24
, rowspan=2, 49.9629880(90)
, rowspan=2, 152.0(6) ms
, β⁺
, ⁵⁰Mn
, rowspan=2, 0+
, rowspan=2,
, rowspan=2,
, -
, β⁺, p?
, ⁴⁹Cr
, -id=Iron-51
, ⁵¹Fe
, style="text-align:right" , 26
, style="text-align:right" , 25
, 50.9568551(15)
, 305.4(23) ms
, β⁺
, ⁵¹Mn
, 5/2−
,
,
, -id=Iron-52
, ⁵²Fe
, style="text-align:right" , 26
, style="text-align:right" , 26
, 51.94811336(19)
, 8.275(8) h
, β⁺
, ⁵²Mn
, 0+
,
,
, -id=Iron-52m
, rowspan=2 style="text-indent:1em" , ^52mFe
, rowspan=2 colspan="3" style="text-indent:2em" , 6960.7(3) keV
, rowspan=2, 45.9(6) s
, β⁺ (99.98%)
, ⁵²Mn
, rowspan=2, 12+
, rowspan=2,
, rowspan=2,
, -
, IT (0.021%)
, ⁵²Fe
, -id=Iron-53
, ⁵³Fe
, style="text-align:right" , 26
, style="text-align:right" , 27
, 52.9453056(18)
, 8.51(2) min
, β⁺
, ⁵³Mn
, 7/2−
,
,
, -id=Iron-53m
, style="text-indent:1em" , ^53mFe
, colspan="3" style="text-indent:2em" , 3040.4(3) keV
, 2.54(2) min
, IT
, ⁵³Fe
, 19/2−
,
,
, -
, ⁵⁴Fe
, style="text-align:right" , 26
, style="text-align:right" , 28
, 53.93960819(37)
, colspan=3 align=center, Observationally Stable
, 0+
, 0.05845(105)
,
, -id=Iron-54m
, style="text-indent:1em" , ^54mFe
, colspan="3" style="text-indent:2em" , 6527.1(11) keV
, 364(7) ns
, IT
, ⁵⁴Fe
, 10+
,
,
, -
, ⁵⁵Fe
, style="text-align:right" , 26
, style="text-align:right" , 29
, 54.93829116(33)
, 2.7562(4) y
, EC
, ⁵⁵Mn
, 3/2−
,
,
, -
, ⁵⁶FeLowest mass per nucleon of all nuclides; End product of stellar nucleosynthesis
, style="text-align:right" , 26
, style="text-align:right" , 30
, 55.93493554(29)
, colspan=3 align=center, Stable
, 0+
, 0.91754(106)
,
, -
, ⁵⁷Fe
, style="text-align:right" , 26
, style="text-align:right" , 31
, 56.93539195(29)
, colspan=3 align=center, Stable
, 1/2−
, 0.02119(29)
,
, -
, ⁵⁸Fe
, style="text-align:right" , 26
, style="text-align:right" , 32
, 57.93327358(34)
, colspan=3 align=center, Stable
, 0+
, 0.00282(12)
,
, -id=Iron-59
, ⁵⁹Fe
, style="text-align:right" , 26
, style="text-align:right" , 33
, 58.93487349(35)
, 44.500(12) d
, β⁻
, ⁵⁹Co
, 3/2−
,
,
, -
, ⁶⁰Fe
, style="text-align:right" , 26
, style="text-align:right" , 34
, 59.9340702(37)
, 2.62(4)×10⁶ y
, β⁻
, ⁶⁰Co
, 0+
, trace
,
, -id=Iron-61
, ⁶¹Fe
, style="text-align:right" , 26
, style="text-align:right" , 35
, 60.9367462(28)
, 5.98(6) min
, β⁻
, ⁶¹Co
, (3/2−)
,
,
, -id=Iron-61m
, style="text-indent:1em" , ^61mFe
, colspan="3" style="text-indent:2em" , 861.67(11) keV
, 238(5) ns
, IT
, ⁶¹Fe
, 9/2+
,
,
, -id=Iron-62
, ⁶²Fe
, style="text-align:right" , 26
, style="text-align:right" , 36
, 61.9367918(30)
, 68(2) s
, β⁻
, ⁶²Co
, 0+
,
,
, -id=Iron-63
, ⁶³Fe
, style="text-align:right" , 26
, style="text-align:right" , 37
, 62.9402727(46)
, 6.1(6) s
, β⁻
, ⁶³Co
, (5/2−)
,
,
, -id=Iron-64
, ⁶⁴Fe
, style="text-align:right" , 26
, style="text-align:right" , 38
, 63.9409878(54)
, 2.0(2) s
, β⁻
, ⁶⁴Co
, 0+
,
,
, -id=Iron-65
, rowspan=2, ⁶⁵Fe
, rowspan=2 style="text-align:right" , 26
, rowspan=2 style="text-align:right" , 39
, rowspan=2, 64.9450153(55)
, rowspan=2, 805(10) ms
, β⁻
, ⁶⁵Co
, rowspan=2, (1/2−)
, rowspan=2,
, rowspan=2,
, -
, β⁻, n?
, ⁶⁴Co
, -id=Iron-65m1
, style="text-indent:1em" , ^65m1Fe
, colspan="3" style="text-indent:2em" , 393.7(2) keV
, 1.12(15) s
, β⁻?
, ⁶⁵Co
, (9/2+)
,
,
, -id=Iron-65m2
, style="text-indent:1em" , ^65m2Fe
, colspan="3" style="text-indent:2em" , 397.6(2) keV
, 418(12) ns
, IT
, ⁶⁵Fe
, (5/2+)
,
,
, -id=Iron-66
, rowspan=2, ⁶⁶Fe
, rowspan=2 style="text-align:right" , 26
, rowspan=2 style="text-align:right" , 40
, rowspan=2, 65.9462500(44)
, rowspan=2, 467(29) ms
, β⁻
, ⁶⁶Co
, rowspan=2, 0+
, rowspan=2,
, rowspan=2,
, -
, β⁻, n?
, ⁶⁵Co
, -id=Iron-67
, rowspan=2, ⁶⁷Fe
, rowspan=2 style="text-align:right" , 26
, rowspan=2 style="text-align:right" , 41
, rowspan=2, 66.9509300(41)
, rowspan=2, 394(9) ms
, β⁻
, ⁶⁷Co
, rowspan=2, (1/2-)
, rowspan=2,
, rowspan=2,
, -
, β⁻, n?
, ⁶⁶Co
, -id=Iron-67m1
, style="text-indent:1em" , ^67m1Fe
, colspan="3" style="text-indent:2em" , 403(9) keV
, 64(17) μs
, IT
, ⁶⁷Fe
, (5/2+,7/2+)
,
,
, -id=Iron-67m2
, style="text-indent:1em" , ^67m2Fe
, colspan="3" style="text-indent:2em" , 450(100)# keV
, 75(21) μs
, IT
, ⁶⁷Fe
, (9/2+)
,
,
, -id=Iron-68
, rowspan=2, ⁶⁸Fe
, rowspan=2 style="text-align:right" , 26
, rowspan=2 style="text-align:right" , 42
, rowspan=2, 67.95288(21)#
, rowspan=2, 188(4) ms
, β⁻
, ⁶⁸Co
, rowspan=2, 0+
, rowspan=2,
, rowspan=2,
, -
, β⁻, n?
, ⁶⁷Co
, -id=Iron-69
, rowspan=3, ⁶⁹Fe
, rowspan=3 style="text-align:right" , 26
, rowspan=3 style="text-align:right" , 43
, rowspan=3, 68.95792(22)#
, rowspan=3, 162(7) ms
, β⁻
, ⁶⁹Co
, rowspan=3, 1/2−#
, rowspan=3,
, rowspan=3,
, -
, β⁻, n?
, ⁶⁸Co
, -
, β⁻, 2n?
, ⁶⁷Co
, -id=Iron-70
, rowspan=2, ⁷⁰Fe
, rowspan=2 style="text-align:right" , 26
, rowspan=2 style="text-align:right" , 44
, rowspan=2, 69.96040(32)#
, rowspan=2, 61.4(7) ms
, β⁻
, ⁷⁰Co
, rowspan=2, 0+
, rowspan=2,
, rowspan=2,
, -
, β⁻, n?
, ⁶⁹Co

, -id=Iron-71
, rowspan=3, ⁷¹Fe
, rowspan=3 style="text-align:right" , 26
, rowspan=3 style="text-align:right" , 45
, rowspan=3, 70.96572(43)#
, rowspan=3, 34.3(26) ms
, β⁻
, ⁷¹Co
, rowspan=3, 7/2+#
, rowspan=3,
, rowspan=3,
, -
, β⁻, n?
, ⁷⁰Co
, -
, β⁻, 2n?
, ⁶⁹Co
, -id=Iron-72
, rowspan=3, ⁷²Fe
, rowspan=3 style="text-align:right" , 26
, rowspan=3 style="text-align:right" , 46
, rowspan=3, 71.96860(54)#
, rowspan=3, 17.0(10) ms
, β⁻
, ⁷²Co
, rowspan=3, 0+
, rowspan=3,
, rowspan=3,
, -
, β⁻, n?
, ⁷¹Co
, -
, β⁻, 2n?
, ⁷⁰Co
, -id=Iron-73
, rowspan=3, ⁷³Fe
, rowspan=3 style="text-align:right" , 26
, rowspan=3 style="text-align:right" , 47
, rowspan=3, 72.97425(54)#
, rowspan=3, 12.9(16) ms
, β⁻
, ⁷³Co
, rowspan=3, 7/2+#
, rowspan=3,
, rowspan=3,
, -
, β⁻, n?
, ⁷²Co
, -
, β⁻, 2n?
, ⁷¹Co
, -id=Iron-74
, rowspan=3, ⁷⁴Fe
, rowspan=3 style="text-align:right" , 26
, rowspan=3 style="text-align:right" , 48
, rowspan=3, 73.97782(54)#
, rowspan=3, 5(5) ms
, β⁻
, ⁷⁴Co
, rowspan=3, 0+
, rowspan=3,
, rowspan=3,
, -
, β⁻, n?
, ⁷³Co
, -
, β⁻, 2n?
, ⁷²Co
, -id=Iron-75
, rowspan=3, ⁷⁵Fe
, rowspan=3 style="text-align:right" , 26
, rowspan=3 style="text-align:right" , 49
, rowspan=3, 74.98422(64)#
, rowspan=3, 9# ms
620 ns, β⁻?
, ⁷⁵Co
, rowspan=3, 9/2+#
, rowspan=3,
, rowspan=3,
, -
, β⁻, n?
, ⁷⁴Co
, -
, β⁻, 2n?
, ⁷³Co
, -id=Iron-76
, ⁷⁶Fe
, style="text-align:right" , 26
, style="text-align:right" , 50
, 75.98863(64)#
, 3# ms
410 ns, β⁻?
, ⁷⁶Co
, 0+
,
,

Iron-54

Fe is observationally stable, but theoretically can decay to Cr, with a half-life of more than years via double electron capture (εε).

Iron-56

Fe is the most abundant isotope of iron. It is also the isotope with the lowest mass per nucleon, 930.412 MeV/c, though not the isotope with the highest nuclear binding energy per nucleon, which is nickel-62. However, because of the details of how nucleosynthesis works, Fe is a more common endpoint of fusion chains inside supernovae, where it is mostly produced as Ni. Thus, Ni is more common in the universe, relative to other metals, including Ni, Fe and Ni, all of which have a very high binding energy.

The high nuclear binding energy of Fe represents the point where further nuclear reactions become energetically unfavorable. Therefore it is among the heaviest elements formed in stellar nucleosynthesis reactions in massive stars. These reactions fuse lighter elements like magnesium, silicon, and sulfur to form heavier elements. Among the heavier elements formed is Ni, which subsequently decays to Co and then Fe.

Iron-57

Fe 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.
The transition was famously used to make the first definitive measurement of gravitational redshift, in the 1960 Pound–Rebka experiment.

Iron-58

Iron-58 can be used to combat anemia and low iron absorption, to metabolically track iron-controlling human genes, and for tracing elements in nature. Iron-58 is also an assisting reagent in the synthesis of superheavy elements.

Iron-60

Iron-60 has a half-life of 2.6 million years, 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 Ni, the granddaughter isotope of Fe, and the abundance of the stable iron isotopes could be found, which is evidence for the existence of Fe at the time of formation of the Solar System. Possibly the energy from the decay of Fe contributed, together with the energy from the decay of the radionuclide Al, to the remelting and differentiation of asteroids after their formation 4.6 billion years ago. The abundance of Ni in extraterrestrial material may also provide further insight into the origin of the Solar System and its early history.

Iron-60 was first identified in deep sea sediments in 1999. These are deep sea ferromanganese crusts, which are constantly growing, aggregating iron, manganese, and other elements. Iron-60 found in fossilized bacteria in sea floor sediments. In 2019, researchers found interstellar Fe in Antarctica. Iron-60 shows two peaks in deep sea sediments, the first 1.7–3.2 million years ago and the second 6.5–8.7 million years ago. The peaks are relate to the passage of the Solar System through the Local Bubble and likely the Orion–Eridanus Superbubble. These superbubbles were created by multiple supernovae.

The distance to the supernova of origin can be estimated by relating the amount of iron-60 intercepted as Earth passes through the expanding supernova ejecta. Assuming that the material ejected in a supernova expands uniformly out from its origin as a sphere with surface area 4πr. The fraction of the material intercepted by the Earth is dependent on its cross-sectional area (πR) as it passes through the expanding debris. Where M is the mass of ejected material.$M_=\frac M_$Assuming the intercepted material is distributed uniformly across the surface of the Earth (4πR), the mass surface density (Σ) of the supernova ejecta on Earth is: $\Sigma_=\frac=\frac$The number of Fe atoms per unit area found on Earth can be estimated if the typical amount of Fe ejected from a supernova is known. This can be done by dividing the surface mass density (Σ) by the atomic mass of Fe. $N_=\left(\frac\right)$The equation for N can be rearranged to find the distance to the supernova.$r=\sqrt$An example calculation for the distance to the supernova point of origin is given below. This calculation uses speculative values for terrestrial Fe atom surface density (N ≈ 4 × 10 atoms/m) and a rough estimate of the mass of Fe ejected by a supernova (10 M). $r=\sqrt$$r=3 \times 10^ m=100 p c$More sophisticated analyses have been reported that take into consideration the flux and deposition of Fe as well as possible interfering background sources.

Cobalt-60, the decay product of iron-60, emits 1.173 MeV and 1.332 MeV as it decays. These gamma-ray lines have long been important targets for gamma-ray astronomy, and have been detected by the gamma-ray observatory INTEGRAL. The signal traces the Galactic plane, showing that Fe synthesis is ongoing in our Galaxy, and probing element production in massive stars.

See also

Daughter products other than iron
* Isotopes of cobalt
* Isotopes of manganese
* Isotopes of chromium
* Isotopes of vanadium

References

Isotope masses from:
*

Isotopic compositions and standard atomic masses from:
*
*

Half-life, spin, and isomer data selected from:
*
*
*

Further reading

*

{{Navbox element isotopes

Iron
Iron