Naturally occurring

nickel Nickel is a chemical element; it has symbol Ni and atomic number 28. It is a silvery-white lustrous metal with a slight golden tinge. Nickel is a hard and ductile transition metal. Pure nickel is chemically reactive, but large pieces are slo ...

(Ni) consists of five stable

isotope Isotopes are distinct nuclear species (or ''nuclides'') of the same chemical element. They have the same atomic number (number of protons in their Atomic nucleus, nuclei) and position in the periodic table (and hence belong to the same chemica ...

s; Ni, Ni, Ni, Ni and Ni; Ni is the most abundant (68.077%

natural abundance In physics, natural abundance (NA) refers to the abundance of isotopes of a chemical element as naturally found on a planet. The relative atomic mass (a weighted average, weighted by mole-fraction abundance figures) of these isotopes is the ato ...

). 26

radioisotope A radionuclide (radioactive nuclide, radioisotope or radioactive isotope) is a nuclide that has excess numbers of either neutrons or protons, giving it excess nuclear energy, and making it unstable. This excess energy can be used in one of three ...

s have been characterized; the most stable are Ni with a

half-life Half-life is a mathematical and scientific description of exponential or gradual decay. Half-life, half life or halflife may also refer to: Film * Half-Life (film), ''Half-Life'' (film), a 2008 independent film by Jennifer Phang * ''Half Life: ...

of 81,000 years, Ni with a half-life of 100.1 years, and Ni (6.077 days). All the other

radioactive Radioactive decay (also known as nuclear decay, radioactivity, radioactive disintegration, or nuclear disintegration) is the process by which an unstable atomic nucleus loses energy by radiation. A material containing unstable nuclei is conside ...

isotopes have half-lives of less than 60 hours and most of these have half-lives of less than 30 seconds. This element also has 8

meta state A nuclear isomer is a metastable state of an atomic nucleus, in which one or more nucleons (protons or neutrons) occupy excited state levels (higher energy levels). "Metastable" describes nuclei whose excited states have half-lives of 10−9 s ...

List of isotopes

, - , rowspan=3, , rowspan=3 style="text-align:right" , 28 , rowspan=3 style="text-align:right" , 20 , rowspan=3, 48.01952(46)# , rowspan=3, 2.8(8) ms , 2 p (70%) , , rowspan=3, 0+ , rowspan=3, , rowspan=3, , - , β⁺ (30%) , , - , β⁺, p? , , -id=Nickel-49 , rowspan=2, , rowspan=2 style="text-align:right" , 28 , rowspan=2 style="text-align:right" , 21 , rowspan=2, 49.00916(64)# , rowspan=2, 7.5(10) ms , β⁺, p (83%) , , rowspan=2, 7/2−# , rowspan=2, , rowspan=2, , - , β⁺ (17%) , , -id=Nickel-50 , rowspan=3, , rowspan=3 style="text-align:right" , 28 , rowspan=3 style="text-align:right" , 22 , rowspan=3, 49.99629(54)# , rowspan=3, 18.5(12) ms , β⁺, p (73%) , , rowspan=3, 0+ , rowspan=3, , rowspan=3, , - , β⁺, 2p (14%) , , - , β⁺ (13%) , , -id=Nickel-51 , rowspan=3, , rowspan=3 style="text-align:right" , 28 , rowspan=3 style="text-align:right" , 23 , rowspan=3, 50.98749(54)# , rowspan=3, 23.8(2) ms , β⁺, p (87.2%) , , rowspan=3, 7/2−# , rowspan=3, , rowspan=3, , - , β⁺ (12.3%) , , - , β⁺, 2p (0.5%) , , -id=Nickel-52 , rowspan=2, , rowspan=2 style="text-align:right" , 28 , rowspan=2 style="text-align:right" , 24 , rowspan=2, 51.975781(89) , rowspan=2, 41.8(10) ms , β⁺ (68.9%) , , rowspan=2, 0+ , rowspan=2, , rowspan=2, , - , β⁺, p (31.1%) , , -id=Nickel-53 , rowspan=2, , rowspan=2 style="text-align:right" , 28 , rowspan=2 style="text-align:right" , 25 , rowspan=2, 52.968190(27) , rowspan=2, 55.2(7) ms , β⁺ (77.3%) , , rowspan=2, (7/2−) , rowspan=2, , rowspan=2, , - , β⁺, p (22.7%) , , -id=Nickel-54 , rowspan=2, , rowspan=2 style="text-align:right" , 28 , rowspan=2 style="text-align:right" , 26 , rowspan=2, 53.9578330(50) , rowspan=2, 114.1(3) ms , β⁺ , , rowspan=2, 0+ , rowspan=2, , rowspan=2, , - , β⁺, p? , , -id=Nickel-54m , rowspan=2 style="text-indent:1em" , , rowspan=2 colspan="3" style="text-indent:2em" , 6457.4(9) keV , rowspan=2, 152(4) ns , IT (64%) , , rowspan=2, 10+ , rowspan=2, , rowspan=2, , - , p (36%) , , -id=Nickel-55 , , style="text-align:right" , 28 , style="text-align:right" , 27 , 54.95132985(76) , 203.9(13) ms , β⁺ , , 7/2− , , , - , rowspan=2, , rowspan=2 style="text-align:right" , 28 , rowspan=2 style="text-align:right" , 28 , rowspan=2, 55.94212776(43) , rowspan=2, 6.075(10) d , EC , , rowspan=2, 0+ , rowspan=2, , rowspan=2, , - , β⁺ (<%) , , -id=Nickel-57 , , style="text-align:right" , 28 , style="text-align:right" , 29 , 56.93979139(61) , 35.60(6) h , β⁺ , , 3/2− , , , - , , style="text-align:right" , 28 , style="text-align:right" , 30 , 57.93534165(37) , colspan=3 align=center,

Observationally stable Stable nuclides are isotopes of a chemical element whose nucleons are in a configuration that does not permit them the surplus energy required to produce a radioactive emission. The nuclei of such isotopes are not radioactive and unlike radionuc ...

Believed to decay by β⁺β⁺ to with a half-life over 7×10²⁰ years , 0+ , 0.680769(190) , , - , rowspan=2 , , rowspan=2 style="text-align:right" , 28 , rowspan=2 style="text-align:right" , 31 , rowspan=2 , 58.93434544(38) , rowspan=2 , 8.1(5)×10⁴ y , EC (99%) , rowspan=2 , , rowspan=2 , 3/2− , rowspan=2 , , rowspan=2 , , - , β⁺ (1.5%) , - , , style="text-align:right" , 28 , style="text-align:right" , 32 , 59.93078513(38) , colspan=3 align=center, Stable , 0+ , 0.262231(150) , , -id=Nickel-61 , , style="text-align:right" , 28 , style="text-align:right" , 33 , 60.93105482(38) , colspan=3 align=center, Stable , 3/2− , 0.011399(13) , , - , Highest

binding energy In physics and chemistry, binding energy is the smallest amount of energy required to remove a particle from a system of particles or to disassemble a system of particles into individual parts. In the former meaning the term is predominantly use ...

per

nucleon In physics and chemistry, a nucleon is either a proton or a neutron, considered in its role as a component of an atomic nucleus. The number of nucleons in a nucleus defines the atom's mass number. Until the 1960s, nucleons were thought to be ele ...

of all nuclides , style="text-align:right" , 28 , style="text-align:right" , 34 , 61.92834475(46) , colspan=3 align=center, Stable , 0+ , 0.036345(40) , , - , , style="text-align:right" , 28 , style="text-align:right" , 35 , 62.92966902(46) , 101.2(15) y , β⁻ , , 1/2− , , , -id=Nickel-63m , style="text-indent:1em" , , colspan="3" style="text-indent:2em" , 87.15(11) keV , 1.67(3) μs , IT , ⁶³Ni , 5/2− , , , - , , style="text-align:right" , 28 , style="text-align:right" , 36 , 63.92796623(50) , colspan=3 align=center, Stable , 0+ , 0.009256(19) , , -id=Nickel-65 , , style="text-align:right" , 28 , style="text-align:right" , 37 , 64.93008459(52) , 2.5175(5) h , β⁻ , , 5/2− , , , -id=Nickel-65m , style="text-indent:1em" , , colspan="3" style="text-indent:2em" , 63.37(5) keV , 69(3) μs , IT , ⁶⁵Ni , 1/2− , , , -id=Nickel-66 , , style="text-align:right" , 28 , style="text-align:right" , 38 , 65.9291393(15) , 54.6(3) h , β⁻ , , 0+ , , , -id=Nickel-67 , , style="text-align:right" , 28 , style="text-align:right" , 39 , 66.9315694(31) , 21(1) s , β⁻ , , 1/2− , , , -id=Nickel-67m , rowspan=2 style="text-indent:1em" , , rowspan=2 colspan="3" style="text-indent:2em" , 1006.6(2) keV , rowspan=2, 13.34(19) μs , IT , , rowspan=2, 9/2+ , rowspan=2, , rowspan=2, , - , IT , , -id=Nickel-68 , , style="text-align:right" , 28 , style="text-align:right" , 40 , 67.9318688(32) , 29(2) s , β⁻ , , 0+ , , , -id=Nickel-68m1 , style="text-indent:1em" , , colspan="3" style="text-indent:2em" , 1603.51(28) keV , 270(5) ns , IT , ⁶⁸Ni , 0+ , , , -id=Nickel-68m2 , style="text-indent:1em" , , colspan="3" style="text-indent:2em" , 2849.1(3) keV , 850(30) μs , IT , ⁶⁸Ni , 5− , , , -id=Nickel-69 , , style="text-align:right" , 28 , style="text-align:right" , 41 , 68.9356103(40) , 11.4(3) s , β⁻ , , (9/2+) , , , -id=Nickel-69m1 , rowspan=2 style="text-indent:1em" , , rowspan=2 colspan="3" style="text-indent:2em" , 321(2) keV , rowspan=2, 3.5(4) s , β⁻ , , rowspan=2, (1/2−) , rowspan=2, , rowspan=2, , - , IT (<0.01%) , , -id=Nickel-69m2 , style="text-indent:1em" , , colspan="3" style="text-indent:2em" , 2700.0(10) keV , 439(3) ns , IT , ⁶⁹Ni , (17/2−) , , , -id=Nickel-70 , , style="text-align:right" , 28 , style="text-align:right" , 42 , 69.9364313(23) , 6.0(3) s , β⁻ , , 0+ , , , -id=Nickel-70m , style="text-indent:1em" , , colspan="3" style="text-indent:2em" , 2860.91(8) keV , 232(1) ns , IT , ⁷⁰Ni , 8+ , , , -id=Nickel-71 , , style="text-align:right" , 28 , style="text-align:right" , 43 , 70.9405190(24) , 2.56(3) s , β⁻ , , (9/2+) , , , -id=Nickel-71m , style="text-indent:1em" , , colspan="3" style="text-indent:2em" , 499(5) keV , 2.3(3) s , β⁻ , ⁷¹Cu , (1/2−) , , , -id=Nickel-72 , rowspan=2, , rowspan=2 style="text-align:right" , 28 , rowspan=2 style="text-align:right" , 44 , rowspan=2, 71.9417859(24) , rowspan=2, 1.57(5) s , β⁻ , , rowspan=2, 0+ , rowspan=2, , rowspan=2, , - , β⁻, n? , , -id=Nickel-73 , rowspan=2, , rowspan=2 style="text-align:right" , 28 , rowspan=2 style="text-align:right" , 45 , rowspan=2, 72.9462067(26) , rowspan=2, 840(30) ms , β⁻ , , rowspan=2, (9/2+) , rowspan=2, , rowspan=2, , - , β⁻, n? , , -id=Nickel-74 , rowspan=2, , rowspan=2 style="text-align:right" , 28 , rowspan=2 style="text-align:right" , 46 , rowspan=2, 73.9479853(38) , rowspan=2, 507.7(46) ms , β⁻ , , rowspan=2, 0+ , rowspan=2, , rowspan=2, , - , β⁻, n? , , -id=Nickel-75 , rowspan=2, , rowspan=2 style="text-align:right" , 28 , rowspan=2 style="text-align:right" , 47 , rowspan=2, 74.952704(16) , rowspan=2, 331.6(32) ms , β⁻ (90.0%) , , rowspan=2, 9/2+# , rowspan=2, , rowspan=2, , - , β⁻, n (10.0%) , , -id=Nickel-76 , rowspan=2, , rowspan=2 style="text-align:right" , 28 , rowspan=2 style="text-align:right" , 48 , rowspan=2, 75.95471(32)# , rowspan=2, 234.6(27) ms , β⁻ (86.0%) , , rowspan=2, 0+ , rowspan=2, , rowspan=2, , - , β⁻, n (14.0%) , , -id=Nickel-76m , style="text-indent:1em" , , colspan="3" style="text-indent:2em" , 2418.0(5) keV , 547.8(33) ns , IT , ⁷⁶Ni , (8+) , , , -id=Nickel-77 , rowspan=3, , rowspan=3 style="text-align:right" , 28 , rowspan=3 style="text-align:right" , 49 , rowspan=3, 76.95990(43)# , rowspan=3, 158.9(42) ms , β⁻ (74%) , , rowspan=3, 9/2+# , rowspan=3, , rowspan=3, , - , β⁻, n (26%) , , - , β⁻, 2n? , , - , rowspan=3, , rowspan=3 style="text-align:right" , 28 , rowspan=3 style="text-align:right" , 50 , rowspan=3, 77.96256(43)# , rowspan=3, 122.2(51) ms , β⁻ , , rowspan=3, 0+ , rowspan=3, , rowspan=3, , - , β⁻, n? , , - , β⁻, 2n? , , -id=Nickel-79 , rowspan=3, , rowspan=3 style="text-align:right" , 28 , rowspan=3 style="text-align:right" , 51 , rowspan=3, 78.96977(54)# , rowspan=3, 44(8) ms , β⁻ , , rowspan=3, 5/2+# , rowspan=3, , rowspan=3, , - , β⁻, n? , , - , β⁻, 2n? , , -id=Nickel-80 , rowspan=3, , rowspan=3 style="text-align:right" , 28 , rowspan=3 style="text-align:right" , 52 , rowspan=3, 79.97505(64)# , rowspan=3, 30(22) ms , β⁻ , , rowspan=3, 0+ , rowspan=3, , rowspan=3, , - , β⁻, n? , , - , β⁻, 2n? , , -id=Nickel-81 , , style="text-align:right" , 28 , style="text-align:right" , 53 , 80.98273(75)# , 30# ms
410 ns, β⁻? , , 3/2+# , , , -id=Nickel-82 , , style="text-align:right" , 28 , style="text-align:right" , 54 , 81.98849(86)# , 16# ms
410 ns, β⁻? , , 0+ , ,

Notable isotopes

The known isotopes of nickel range in

mass number The mass number (symbol ''A'', from the German word: ''Atomgewicht'', "atomic weight"), also called atomic mass number or nucleon number, is the total number of protons and neutrons (together known as nucleons) in an atomic nucleus. It is appro ...

from Ni to Ni, and include: Nickel-48, discovered in 1999, is the most neutron-poor nickel isotope known. With 28

proton A proton is a stable subatomic particle, symbol , Hydron (chemistry), H+, or 1H+ with a positive electric charge of +1 ''e'' (elementary charge). Its mass is slightly less than the mass of a neutron and approximately times the mass of an e ...

s and 20

neutron The neutron is a subatomic particle, symbol or , that has no electric charge, and a mass slightly greater than that of a proton. The Discovery of the neutron, neutron was discovered by James Chadwick in 1932, leading to the discovery of nucle ...

s Ni is " doubly magic" (like ) and therefore much more stable (with a lower limit of its half-life-time of .5 μs) than would be expected from its position in the chart of nuclides. It has the highest ratio of protons to neutrons (proton excess) of any known doubly magic nuclide. Nickel-56 is produced in large quantities in

supernova A supernova (: supernovae or supernovas) is a powerful and luminous explosion of a star. A supernova occurs during the last stellar evolution, evolutionary stages of a massive star, or when a white dwarf is triggered into runaway nuclear fusion ...

e. In the last phases of

stellar evolution Stellar evolution is the process by which a star changes over the course of time. Depending on the mass of the star, its lifetime can range from a few million years for the most massive to trillions of years for the least massive, which is consi ...

of very large stars, fusion of lighter elements like hydrogen and helium comes to an end. Later in the star's life cycle, elements including magnesium, silicon, and sulfur are fused to form heavier elements. Once the last nuclear fusion reactions cease, the star collapses to produce a

. During the supernova, silicon burning produces Ni. This isotope of nickel is favored because it has an equal number of neutrons and protons, making it readily produced by fusing two Si atoms. Ni is the last element that can be formed in the

alpha process The alpha process, also known as alpha capture or the alpha ladder, is one of two classes of nuclear fusion reactions by which stars convert helium into heavier elements. The other class is a cycle of reactions called the triple-alpha process, w ...

. Past Ni, nuclear reactions are endoergic and energetically unfavorable. Ni decays to Co and then Fe by

β+ decay In nuclear physics, beta decay (β-decay) is a type of radioactive decay in which an atomic nucleus emits a beta particle (fast energetic electron or positron), transforming into an isobar (nuclide), isobar of that nuclide. For example, beta dec ...

. The

radioactive decay Radioactive decay (also known as nuclear decay, radioactivity, radioactive disintegration, or nuclear disintegration) is the process by which an unstable atomic nucleus loses energy by radiation. A material containing unstable nuclei is conside ...

of Ni and Co supplies much of the energy for the light curves observed for stellar supernovae. The shape of the

light curve In astronomy, a light curve is a graph (discrete mathematics), graph of the Radiance, light intensity of a celestial object or region as a function of time, typically with the magnitude (astronomy), magnitude of light received on the ''y''-axis ...

of these supernovae display characteristic timescales corresponding to the decay of Ni to Co and then to Fe. Nickel-58 is the most abundant isotope of nickel, making up 68.077% of the

. Possible sources include

electron capture Electron capture (K-electron capture, also K-capture, or L-electron capture, L-capture) is a process in which the proton-rich nucleus of an electrically neutral atom absorbs an inner atomic electron, usually from the K or L electron shells. Th ...

(EC) from copper-58, and EC + p from

zinc-59 Naturally occurring zinc (30Zn) is composed of the 5 stable isotopes 64Zn, 66Zn, 67Zn, 68Zn, and 70Zn with 64Zn being the most abundant (48.6% natural abundance). Twenty-eight radioisotopes have been characterised with the most stable being 65Zn ...

. Nickel-59 is a long-lived

cosmogenic Cosmogenic nuclides (or cosmogenic isotopes) are rare nuclides (isotopes) created when a high-energy cosmic ray interacts with the nucleus of an ''in situ'' Solar System atom, causing nucleons (protons and neutrons) to be expelled from the atom ( ...

radionuclide A radionuclide (radioactive nuclide, radioisotope or radioactive isotope) is a nuclide that has excess numbers of either neutrons or protons, giving it excess nuclear energy, and making it unstable. This excess energy can be used in one of three ...

with a half-life of 81,000 years. Ni has found many applications in

isotope geology Isotope geochemistry is an aspect of geology based upon the study of natural variations in the relative abundances of isotopes of various elements. Variations in isotopic abundance are measured by isotope-ratio mass spectrometry, and can reveal ...

. Ni has been used to date the terrestrial age of

meteorite A meteorite is a rock (geology), rock that originated in outer space and has fallen to the surface of a planet or Natural satellite, moon. When the original object enters the atmosphere, various factors such as friction, pressure, and chemical ...

s and to determine abundances of extraterrestrial dust in ice and

sediment Sediment is a solid material that is transported to a new location where it is deposited. It occurs naturally and, through the processes of weathering and erosion, is broken down and subsequently sediment transport, transported by the action of ...

. Nickel-60 is the daughter product of the

extinct radionuclide An extinct radionuclide is a radionuclide that was formed by nucleosynthesis before the formation of the Solar System, about 4.6 billion years ago, but has since decayed to virtually zero abundance and is no longer detectable as a primordial nu ...

(half-life 2.6 My). Because Fe has such a long half-life, its persistence in materials in the

Solar System The Solar SystemCapitalization of the name varies. The International Astronomical Union, the authoritative body regarding astronomical nomenclature, specifies capitalizing the names of all individual astronomical objects but uses mixed "Sola ...

at high enough concentrations may have generated observable variations in the isotopic composition of Ni. Therefore, the abundance of Ni in extraterrestrial material may provide insight into the origin of the Solar System and its early history/very early history. Unfortunately, nickel isotopes appear to have been heterogeneously distributed in the early Solar System. Therefore, so far, no actual age information has been attained from Ni excesses. Ni is also the stable end-product of the decay of Zn, the product of the final rung of the alpha ladder. Other sources may also include

beta decay In nuclear physics, beta decay (β-decay) is a type of radioactive decay in which an atomic nucleus emits a beta particle (fast energetic electron or positron), transforming into an isobar of that nuclide. For example, beta decay of a neutron ...

from

cobalt-60 Cobalt-60 (Co) is a synthetic radioactive isotope of cobalt with a half-life of 5.2714 years. It is produced artificially in nuclear reactors. Deliberate industrial production depends on neutron activation of bulk samples of the monoisotop ...

and electron capture from copper-60. Nickel-61 is the only stable isotope of nickel with a nuclear spin (''I'' = 3/2), which makes it useful for studies by EPR spectroscopy.

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 (8.7945 MeV). It is often stated that 56Fe is the "most stable nucleus", but only beca ...

has the highest

per nucleon of any isotope for any element, when including the electron shell in the calculation. More energy is released forming this isotope than any other, though fusion can form heavier isotopes. For instance, two Ca atoms can fuse to form Kr plus 4 positrons (plus 4 neutrinos), liberating 77 keV per nucleon, but reactions leading to the iron/nickel region are more probable as they release more energy per baryon. Nickel-63 has two main uses: Detection of explosives traces, and in certain kinds of electronic devices, such as gas discharge tubes used as

surge protector A surge protector, spike suppressor, surge suppressor, surge diverter, surge protection device (SPD), transient voltage suppressor (TVS) or transient voltage surge suppressor (TVSS) is an appliance or device intended to protect Electronics, ele ...

s. A surge protector is a device that protects sensitive electronic equipment like computers from sudden changes in the electric current flowing into them. It is also used in

Electron capture detector An electron capture detector (ECD) is a device for detecting atoms and molecules in a gas through the attachment of electrons via electron capture ionization. The device was invented in 1957 by James Lovelock and is used in gas chromatography to ...

gas chromatography Gas chromatography (GC) is a common type of chromatography used in analytical chemistry for Separation process, separating and analyzing compounds that can be vaporized without Chemical decomposition, decomposition. Typical uses of GC include t ...

for the detection mainly of halogens. It is proposed to be used for miniature betavoltaic generators for pacemakers. Nickel-64 is another stable isotope of nickel. Possible sources include

from cobalt-64, and electron capture from

copper-64 Copper-64 (Cu) is a positron and beta emitting isotope of copper, with applications for molecular radiotherapy and positron emission tomography. Its unusually long half-life (12.7-hours) for a positron-emitting isotope makes it increasingly usef ...

. Nickel-78 is one of the element's heaviest known isotopes. With 28 protons and 50 neutrons, nickel-78 is doubly magic, resulting in much greater

nuclear binding energy Nuclear binding energy in experimental physics is the minimum energy that is required to disassemble the nucleus of an atom into its constituent protons and neutrons, known collectively as nucleons. The binding energy for stable nuclei is alwa ...

and stability despite a lopsided neutron-proton ratio. Its half-life is milliseconds. Due to its magic neutron number, Ni is believed to have an important role in

supernova nucleosynthesis Supernova nucleosynthesis is the nucleosynthesis of chemical elements in supernova explosions. In sufficiently massive stars, the nucleosynthesis by fusion of lighter elements into heavier ones occurs during sequential hydrostatic burning process ...

of elements heavier than iron. Ni, along with ''N'' = 50 isotones Cu and Zn, are thought to constitute a waiting point in the ''r''-process, where further

neutron capture Neutron capture is a nuclear reaction in which an atomic nucleus and one or more neutrons collide and merge to form a heavier nucleus. Since neutrons have no electric charge, they can enter a nucleus more easily than positively charged protons, wh ...

is delayed by the shell gap and a buildup of isotopes around ''A'' = 80 results.

References

* Isotope masses from: ** * Isotopic compositions and standard atomic masses from: ** ** * Half-life, spin, and isomer data selected from the following sources. ** ** ** ** {{Navbox element isotopes Nickel

Nickel Nickel is a chemical element; it has symbol Ni and atomic number 28. It is a silvery-white lustrous metal with a slight golden tinge. Nickel is a hard and ductile transition metal. Pure nickel is chemically reactive, but large pieces are slo ...

List of isotopes

Notable isotopes

See also

References