Isotopes of iron
Encyclopedia
Naturally occurring iron
(Fe) consists of four isotope
s: 5.845% of 54Fe (possibly radioactive with a half-life over 3.1×1022 years), 91.754% of 56Fe, 2.119% of 57Fe and 0.282% of 58Fe. There are 24 known radioactive isotopes and their half-lives are shown below. See Brookhaven National Laboratory Interactive Table of Nuclides for a more accurate reading.
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 isotope
s 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.
per nucleon, which is Nickel-62
. 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.
to cobalt-60
.
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 asteroid
s 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.
Standard atomic mass: 55.845(2) u
Iron
Iron is a chemical element with the symbol Fe and atomic number 26. It is a metal in the first transition series. It is the most common element forming the planet Earth as a whole, forming much of Earth's outer and inner core. It is the fourth most common element in the Earth's crust...
(Fe) consists of four isotope
Isotope
Isotopes are variants of atoms of a particular chemical element, which have differing numbers of neutrons. Atoms of a particular element by definition must contain the same number of protons but may have a distinct number of neutrons which differs from atom to atom, without changing the designation...
s: 5.845% of 54Fe (possibly radioactive with a half-life over 3.1×1022 years), 91.754% of 56Fe, 2.119% of 57Fe and 0.282% of 58Fe. There are 24 known radioactive isotopes and their half-lives are shown below. See Brookhaven National Laboratory Interactive Table of Nuclides for a more accurate reading.
Much of the past work on measuring the isotopic composition of Fe has centered on determining 60Fe variations due to processes accompanying nucleosynthesis
Nucleosynthesis
Nucleosynthesis is the process of creating new atomic nuclei from pre-existing nucleons . It is thought that the primordial nucleons themselves were formed from the quark–gluon plasma from the Big Bang as it cooled below two trillion degrees...
(i.e., meteorite
Meteorite
A meteorite is a natural object originating in outer space that survives impact with the Earth's surface. Meteorites can be big or small. Most meteorites derive from small astronomical objects called meteoroids, but they are also sometimes produced by impacts of asteroids...
studies) and ore formation. In the last decade however, advances in mass spectrometry
Mass spectrometry
Mass spectrometry is an analytical technique that measures the mass-to-charge ratio of charged particles.It is used for determining masses of particles, for determining the elemental composition of a sample or molecule, and for elucidating the chemical structures of molecules, such as peptides and...
technology have allowed the detection and quantification of minute, naturally occurring variations in the ratios of the stable isotope
Stable isotope
Stable isotopes are chemical isotopes that may or may not be radioactive, but if radioactive, have half-lives too long to be measured.Only 90 nuclides from the first 40 elements are energetically stable to any kind of decay save proton decay, in theory...
s of iron. Much of this work has been driven by the Earth
Earth science
Earth science is an all-embracing term for the sciences related to the planet Earth. It is arguably a special case in planetary science, the Earth being the only known life-bearing planet. There are both reductionist and holistic approaches to Earth sciences...
and planetary science
Planetary science
Planetary science is the scientific study of planets , moons, and planetary systems, in particular those of the Solar System and the processes that form them. It studies objects ranging in size from micrometeoroids to gas giants, aiming to determine their composition, dynamics, formation,...
communities, although applications to biological and industrial systems are beginning to emerge.
Iron-54
54Fe is observationally stable, with a branching theory that it decays to 54Cr, with a half-life of more than 3.1x1022 years via double electron capture (2β+). All other natural isotopes are known to be stable, which makes 54Fe seemingly strange.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 energyNuclear binding energy
Nuclear binding energy is the energy required to split a nucleus of an atom into its component parts. The component parts are neutrons and protons, which are collectively called nucleons...
per nucleon, which is Nickel-62
Nickel-62
Nickel-62 is an isotope of nickel having 28 protons and 34 neutrons.It is a stable isotope, with the highest binding energy per nucleon of any known nuclide . It is often stated that 56Fe is the "most stable nucleus", but actually 56Fe has the lowest mass per nucleon of all nuclides...
. 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
Metallicity
In astronomy and physical cosmology, the metallicity of an object is the proportion of its matter made up of chemical elements other than hydrogen and helium...
, 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 due to the low natural variation in energy of the 14.4keV nuclear transition.Iron-60
Iron-60 is another isotope. It 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 decayBeta decay
In nuclear physics, beta decay is a type of radioactive decay in which a beta particle is emitted from an atom. There are two types of beta decay: beta minus and beta plus. In the case of beta decay that produces an electron emission, it is referred to as beta minus , while in the case of a...
to cobalt-60
Cobalt-60
Cobalt-60, , is a synthetic radioactive isotope of cobalt. Due to its half-life of 5.27 years, is not found in nature. It is produced artificially by neutron activation of . decays by beta decay to the stable isotope nickel-60...
.
In phases of the meteorites Semarkona and Chervony Kut a correlation between the concentration of 60Ni
Nickel
Nickel is a chemical element with the chemical symbol Ni and atomic number 28. It is a silvery-white lustrous metal with a slight golden tinge. Nickel belongs to the transition metals and is hard and ductile...
, 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
Aluminium
Aluminium or aluminum is a silvery white member of the boron group of chemical elements. It has the symbol Al, and its atomic number is 13. It is not soluble in water under normal circumstances....
, to the remelting and differentiation
Planetary differentiation
In planetary science, planetary differentiation is the process of separating out different constituents of a planetary body as a consequence of their physical or chemical behaviour, where the body develops into compositionally distinct layers; the denser materials of a planet sink to the center,...
of asteroid
Asteroid
Asteroids are a class of small Solar System bodies in orbit around the Sun. They have also been called planetoids, especially the larger ones...
s after their formation 4.6 billion years ago. The abundance of 60Ni
Nickel
Nickel is a chemical element with the chemical symbol Ni and atomic number 28. It is a silvery-white lustrous metal with a slight golden tinge. Nickel belongs to the transition metals and is hard and ductile...
present in extraterrestrial material may also provide further insight into the origin of the solar system
Solar System
The Solar System consists of the Sun and the astronomical objects gravitationally bound in orbit around it, all of which formed from the collapse of a giant molecular cloud approximately 4.6 billion years ago. The vast majority of the system's mass is in the Sun...
and its early history.
Standard atomic mass: 55.845(2) u
Table
| nuclide symbol |
Z(p Proton The proton is a subatomic particle with the symbol or and a positive electric charge of 1 elementary charge. One or more protons are present in the nucleus of each atom, along with neutrons. The number of protons in each atom is its atomic number.... ) |
N(n Neutron The neutron is a subatomic hadron particle which has the symbol or , no net electric charge and a mass slightly larger than that of a proton. With the exception of hydrogen, nuclei of atoms consist of protons and neutrons, which are therefore collectively referred to as nucleons. The number of... ) |
isotopic mass (u) |
half-life | decay mode(s)Abbreviations: EC: Electron capture Electron capture Electron capture is a process in which a proton-rich nuclide absorbs an inner atomic electron and simultaneously emits a neutrino... IT: Isomeric transition Isomeric transition An isomeric transition is a radioactive decay process that involves emission of a gamma ray from an atom where the nucleus is in an excited metastable state, referred to in its excited state, as a nuclear isomer.... |
daughter isotope(s)Bold for stable isotopes |
nuclear spin |
representative isotopic composition (mole fraction) |
range of natural variation (mole fraction) |
|---|---|---|---|---|---|---|---|---|---|
| excitation energy | |||||||||
| 45Fe | 26 | 19 | 45.01458(24)# | 1.89(49) ms Second The second is a unit of measurement of time, and is the International System of Units base unit of time. It may be measured using a clock.... |
β+ Beta decay In nuclear physics, beta decay is a type of radioactive decay in which a beta particle is emitted from an atom. There are two types of beta decay: beta minus and beta plus. In the case of beta decay that produces an electron emission, it is referred to as beta minus , while in the case of a... (30%) |
45Mn | 3/2+# | ||
| 2p (70%) | 43Cr | ||||||||
| 46Fe | 26 | 20 | 46.00081(38)# | 9(4) ms [12(+4-3) ms] |
β+ Beta decay In nuclear physics, beta decay is a type of radioactive decay in which a beta particle is emitted from an atom. There are two types of beta decay: beta minus and beta plus. In the case of beta decay that produces an electron emission, it is referred to as beta minus , while in the case of a... (>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 Hour The hour is a unit of measurement of time. In modern usage, an hour comprises 60 minutes, or 3,600 seconds... |
β+ | 52Mn | 0+ | ||
| 52mFe | 6.81(13) MeV | 45.9(6) s | β+ | 52Mn | (12+)# | ||||
| 53Fe | 26 | 27 | 52.9453079(19) | 8.51(2) min Minute A minute is a unit of measurement of time or of angle. The minute is a unit of time equal to 1/60th of an hour or 60 seconds. In the UTC time scale, a minute on rare occasions has 59 or 61 seconds; see leap second. The minute is not an SI unit; however, it is accepted for use with SI units... |
β+ | 53Mn | 7/2- | ||
| 53mFe | 3040.4(3) keV | 2.526(24) min | IT Isomeric transition An isomeric transition is a radioactive decay process that involves emission of a gamma ray from an atom where the nucleus is in an excited metastable state, referred to in its excited state, as a nuclear isomer.... |
53Fe | 19/2- | ||||
| 54Fe | 26 | 28 | 53.9396105(7) | Observationally StableBelieved to decay by β+β+ to 54Cr with a half-life of over 3.1×1022 a | 0+ | 0.05845(35) | 0.05837-0.05861 | ||
| 54mFe | 6526.9(6) keV | 364(7) ns | 10+ | ||||||
| 55Fe Iron-55 Iron-55 or 55Fe is a radioactive isotope of iron with a nucleus containing 26 protons and 29 neutrons. It decays by electron capture to manganese-55 and this process has a half-life of 2.737 years. The emitted X-rays can be used as an X-ray source for various scientific analysis methods, such as... |
26 | 29 | 54.9382934(7) | 2.737(11) a | EC Electron capture Electron capture is a process in which a proton-rich nuclide absorbs an inner atomic electron and simultaneously emits a neutrino... |
55Mn | 3/2- | ||
| 56Fe Iron-56 Iron-56 is the most common isotope of iron. About 91.754% of all iron is iron-56.Of all isotopes, iron-56 has the lowest mass per nucleon. With 8.8 MeV binding energy per nucleon, iron-56 is one of the most tightly bound nuclei.... Lowest mass per nucleon of all nuclides; End product of stellar nucleosynthesis Nucleosynthesis Nucleosynthesis is the process of creating new atomic nuclei from pre-existing nucleons . It is thought that the primordial nucleons themselves were formed from the quark–gluon plasma from the Big Bang as it cooled below two trillion degrees... |
26 | 30 | 55.9349375(7) | Stable | 0+ | 0.91754(36) | 0.91742-0.91760 | ||
| 57Fe | 26 | 31 | 56.9353940(7) | Stable | 1/2- | 0.02119(10) | 0.02116-0.02121 | ||
| 58Fe | 26 | 32 | 57.9332756(8) | Stable | 0+ | 0.00282(4) | 0.00281-0.00282 | ||
| 59Fe | 26 | 33 | 58.9348755(8) | 44.495(9) d Day A day is a unit of time, commonly defined as an interval equal to 24 hours. It also can mean that portion of the full day during which a location is illuminated by the light of the sun... |
β- | 59Co | 3/2- | ||
| 60Fe | 26 | 34 | 59.934072(4) | 2.6×106 a | β- | 60Co | 0+ | trace Trace radioisotope A trace radioisotope is a radioisotope that occurs naturally in trace amounts . Generally speaking, trace radioisotopes have half-lives that are short in comparison to the age of the earth, since primordial nuclides tend to occur in larger than trace amounts... |
|
| 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 Neutron emission Neutron emission is a type of radioactive decay of atoms containing excess neutrons, in which a neutron is simply ejected from the nucleus. Two examples of isotopes which emit neutrons are helium-5 and beryllium-13... (<.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+ | ||||