Isotopes of iridium
Encyclopedia
There are two natural isotope
s of iridium
(Ir), and 34 radioisotopes, the most stable radioisotope being 192Ir with a half-life
of 73.83 days, and many nuclear isomer
s, the most stable of which is 192m2Ir with a half-life of 241 years, all other isomers have half-lives under a year, most under a day.
Standard atomic mass: 192.217(3) u
of iridium
, with a half-life
of 73.83 days. It decays by emitting beta (β) particles and gamma (γ) radiation. About 96% of 192Ir decays occur via emission of β and γ radiation, leading to 192Pt-192. Some of the β particles is captured by other 192Ir nuclei, which are then converted to 192Os. Electron capture is responsible for the remaining 4% of 192Ir decays.
Iridium-192 is also a strong gamma ray emitter. There are seven principal energy packets produced during its disintegration process ranging from just over 0.2 to about 0.6 MeV. Iridium-192 is commonly used as a gamma ray source in industrial radiography
to locate flaws in metal components. It is also used in radiotherapy as a radiation source.
Iridium-192 has accounted for the majority of cases tracked by the US Nuclear Regulatory Commission
in which radioactive materials have gone missing in quantities large enough to make a dirty bomb
.
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 of iridium
Iridium
Iridium is the chemical element with atomic number 77, and is represented by the symbol Ir. A very hard, brittle, silvery-white transition metal of the platinum family, iridium is the second-densest element and is the most corrosion-resistant metal, even at temperatures as high as 2000 °C...
(Ir), and 34 radioisotopes, the most stable radioisotope being 192Ir with a half-life
Half-life
Half-life, abbreviated t½, is the period of time it takes for the amount of a substance undergoing decay to decrease by half. The name was originally used to describe a characteristic of unstable atoms , but it may apply to any quantity which follows a set-rate decay.The original term, dating to...
of 73.83 days, and many nuclear isomer
Nuclear isomer
A nuclear isomer is a metastable state of an atomic nucleus caused by the excitation of one or more of its nucleons . "Metastable" refers to the fact that these excited states have half-lives more than 100 to 1000 times the half-lives of the other possible excited nuclear states...
s, the most stable of which is 192m2Ir with a half-life of 241 years, all other isomers have half-lives under a year, most under a day.
Standard atomic mass: 192.217(3) u
Iridium-192
Iridium-192 (symbol 192Ir) is a radioactive isotopeIsotope
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...
of iridium
Iridium
Iridium is the chemical element with atomic number 77, and is represented by the symbol Ir. A very hard, brittle, silvery-white transition metal of the platinum family, iridium is the second-densest element and is the most corrosion-resistant metal, even at temperatures as high as 2000 °C...
, with a half-life
Half-life
Half-life, abbreviated t½, is the period of time it takes for the amount of a substance undergoing decay to decrease by half. The name was originally used to describe a characteristic of unstable atoms , but it may apply to any quantity which follows a set-rate decay.The original term, dating to...
of 73.83 days. It decays by emitting beta (β) particles and gamma (γ) radiation. About 96% of 192Ir decays occur via emission of β and γ radiation, leading to 192Pt-192. Some of the β particles is captured by other 192Ir nuclei, which are then converted to 192Os. Electron capture is responsible for the remaining 4% of 192Ir decays.
Iridium-192 is also a strong gamma ray emitter. There are seven principal energy packets produced during its disintegration process ranging from just over 0.2 to about 0.6 MeV. Iridium-192 is commonly used as a gamma ray source in industrial radiography
Industrial radiography
Industrial Radiography is the use of ionizing radiation to view objects in a way that cannot be seen otherwise. It is not to be confused with the use of ionizing radiation to change or modify objects; radiography's purpose is strictly viewing. Industrial radiography has grown out of engineering,...
to locate flaws in metal components. It is also used in radiotherapy as a radiation source.
Iridium-192 has accounted for the majority of cases tracked by the US Nuclear Regulatory Commission
Nuclear Regulatory Commission
The Nuclear Regulatory Commission is an independent agency of the United States government that was established by the Energy Reorganization Act of 1974 from the United States Atomic Energy Commission, and was first opened January 19, 1975...
in which radioactive materials have gone missing in quantities large enough to make a dirty bomb
Dirty bomb
A dirty bomb is a speculative radiological weapon that combines radioactive material with conventional explosives. The purpose of the weapon is to contaminate the area around the explosion with radioactive material, hence the attribute "dirty"....
.
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, bold italics for nearly-stable isotopes (half-life longer than the age of the universe Age of the universe The age of the universe is the time elapsed since the Big Bang posited by the most widely accepted scientific model of cosmology. The best current estimate of the age of the universe is 13.75 ± 0.13 billion years within the Lambda-CDM concordance model... ) |
nuclear spin |
representative isotopic composition (mole fraction) |
range of natural variation (mole fraction) |
|---|---|---|---|---|---|---|---|---|---|
| excitation energy | |||||||||
| 164Ir | 77 | 87 | 163.99220(44)# | 1# ms | 2-# | ||||
| 164mIr | 270(110)# keV | 94(27) µs | 9+# | ||||||
| 165Ir | 77 | 88 | 164.98752(23)# | <1# µs | p Proton emission Proton emission is a type of radioactive decay in which a proton is ejected from a nucleus. Proton emission can occur from high-lying excited states in a nucleus following a beta decay, in which case the process is known as beta-delayed proton emission, or can occur from the ground state of very... |
164Os | 1/2+# | ||
| α Alpha decay Alpha decay is a type of radioactive decay in which an atomic nucleus emits an alpha particle and thereby transforms into an atom with a mass number 4 less and atomic number 2 less... (rare) |
161Re | ||||||||
| 165mIr | 180(50)# keV | 300(60) µs | p (87%) | 164Os | 11/2- | ||||
| α (13%) | 161Re | ||||||||
| 166Ir | 77 | 89 | 165.98582(22)# | 10.5(22) ms | α (93%) | 162Re | (2-) | ||
| p (7%) | 165Os | ||||||||
| 166mIr | 172(6) keV | 15.1(9) ms | α (98.2%) | 162Re | (9+) | ||||
| p (1.8%) | 165Os | ||||||||
| 167Ir | 77 | 90 | 166.981665(20) | 35.2(20) ms | α (48%) | 163Re | 1/2+ | ||
| p (32%) | 166Os | ||||||||
| 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... (20%) |
167Os | ||||||||
| 167mIr | 175.3(22) keV | 30.0(6) ms | α (80%) | 163Re | 11/2- | ||||
| β+ (20%) | 167Os | ||||||||
| p (.4%) | 166Os | ||||||||
| 168Ir | 77 | 91 | 167.97988(16)# | 161(21) ms | α | 164Re | high | ||
| β+ (rare) | 168Os | ||||||||
| 168mIr | 50(100)# keV | 125(40) ms | α | 164Re | low | ||||
| 169Ir | 77 | 92 | 168.976295(28) | 780(360) ms [0.64(+46-24) s] |
α | 165Re | 1/2+# | ||
| β+ (rare) | 169Os | ||||||||
| 169mIr | 154(24) keV | 308(22) ms | α (72%) | 165Re | 11/2-# | ||||
| β+ (28%) | 169Os | ||||||||
| 170Ir | 77 | 93 | 169.97497(11)# | 910(150) ms [0.87(+18-12) s] |
β+ (64%) | 170Os | low# | ||
| α (36%) | 166Re | ||||||||
| 170mIr | 270(70)# keV | 440(60) ms | high# | ||||||
| 171Ir | 77 | 94 | 170.97163(4) | 3.6(10) s [3.2(+13-7) s] |
α (58%) | 167Re | 1/2+# | ||
| β+ (42%) | 171Os | ||||||||
| 171mIr | 180(30)# keV | 1.40(10) s | (11/2-) | ||||||
| 172Ir | 77 | 95 | 171.97046(11)# | 4.4(3) s | β+ (98%) | 172Os | (3+) | ||
| α (2%) | 168Re | ||||||||
| 172mIr | 280(100)# keV | 2.0(1) s | β+ (77%) | 172Os | (7+) | ||||
| α (23%) | 168Re | ||||||||
| 173Ir | 77 | 96 | 172.967502(15) | 9.0(8) s | β+ (93%) | 173Os | (3/2+,5/2+) | ||
| α (7%) | 169Re | ||||||||
| 173mIr | 253(27) keV | 2.20(5) s | β+ (88%) | 173Os | (11/2-) | ||||
| α (12%) | 169Re | ||||||||
| 174Ir | 77 | 97 | 173.966861(30) | 7.9(6) s | β+ (99.5%) | 174Os | (3+) | ||
| α (.5%) | 170Re | ||||||||
| 174mIr | 193(11) keV | 4.9(3) s | β+ (99.53%) | 174Os | (7+) | ||||
| α (.47%) | 170Re | ||||||||
| 175Ir | 77 | 98 | 174.964113(21) | 9(2) s | β+ (99.15%) | 175Os | (5/2-) | ||
| α (.85%) | 171Re | ||||||||
| 176Ir | 77 | 99 | 175.963649(22) | 8.3(6) s | β+ (97.9%) | 176Os | |||
| α (2.1%) | 172Re | ||||||||
| 177Ir | 77 | 100 | 176.961302(21) | 30(2) s | β+ (99.94%) | 177Os | 5/2- | ||
| α (.06%) | 173Re | ||||||||
| 178Ir | 77 | 101 | 177.961082(21) | 12(2) s | β+ | 178Os | |||
| 179Ir | 77 | 102 | 178.959122(12) | 79(1) s | β+ | 179Os | (5/2)- | ||
| 180Ir | 77 | 103 | 179.959229(23) | 1.5(1) min | β+ | 180Os | (4,5)(+#) | ||
| 181Ir | 77 | 104 | 180.957625(28) | 4.90(15) min | β+ | 181Os | (5/2)- | ||
| 182Ir | 77 | 105 | 181.958076(23) | 15(1) min | β+ | 182Os | (3+) | ||
| 183Ir | 77 | 106 | 182.956846(27) | 57(4) min | β+ ( 99.95%) | 183Os | 5/2- | ||
| α (.05%) | 179Re | ||||||||
| 184Ir | 77 | 107 | 183.95748(3) | 3.09(3) h | β+ | 184Os | 5- | ||
| 184m1Ir | 225.65(11) keV | 470(30) µs | 3+ | ||||||
| 184m2Ir | 328.40(24) keV | 350(90) ns | (7)+ | ||||||
| 185Ir | 77 | 108 | 184.95670(3) | 14.4(1) h | β+ | 185Os | 5/2- | ||
| 186Ir | 77 | 109 | 185.957946(18) | 16.64(3) h | β+ | 186Os | 5+ | ||
| 186mIr | 0.8(4) keV | 1.92(5) h | β+ | 186Os | 2- | ||||
| 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.... (rare) |
186Ir | ||||||||
| 187Ir | 77 | 110 | 186.957363(7) | 10.5(3) h | β+ | 187Os | 3/2+ | ||
| 187m1Ir | 186.15(4) keV | 30.3(6) ms | IT | 187Ir | 9/2- | ||||
| 187m2Ir | 433.81(9) keV | 152(12) ns | 11/2- | ||||||
| 188Ir | 77 | 111 | 187.958853(8) | 41.5(5) h | β+ | 188Os | 1- | ||
| 188mIr | 970(30) keV | 4.2(2) ms | IT | 188Ir | 7+# | ||||
| β+ (rare) | 188Os | ||||||||
| 189Ir | 77 | 112 | 188.958719(14) | 13.2(1) d | EC Electron capture Electron capture is a process in which a proton-rich nuclide absorbs an inner atomic electron and simultaneously emits a neutrino... |
189Os | 3/2+ | ||
| 189m1Ir | 372.18(4) keV | 13.3(3) ms | IT | 189Ir | 11/2- | ||||
| 189m2Ir | 2333.3(4) keV | 3.7(2) ms | (25/2)+ | ||||||
| 190Ir | 77 | 113 | 189.9605460(18) | 11.78(10) d | β+ | 190Os | 4- | ||
| 190m1Ir | 26.1(1) keV | 1.120(3) h | IT | 190Ir | (1-) | ||||
| 190m2Ir | 36.154(25) keV | >2 µs | (4)+ | ||||||
| 190m3Ir | 376.4(1) keV | 3.087(12) h | (11)- | ||||||
| 191Ir | 77 | 114 | 190.9605940(18) | Observationally StableBelieved to undergo α decay to 187Re | 3/2+ | 0.373(2) | |||
| 191m1Ir | 171.24(5) keV | 4.94(3) s | IT | 191Ir | 11/2- | ||||
| 191m2Ir | 2120(40) keV | 5.5(7) s | |||||||
| 192Ir | 77 | 115 | 191.9626050(18) | 73.827(13) d | β- (95.24%) | 192Pt | 4+ | ||
| EC (4.76%) | 192Os | ||||||||
| 192m1Ir | 56.720(5) keV | 1.45(5) min | 1- | ||||||
| 192m2Ir | 168.14(12) keV | 241(9) a | (11-) | ||||||
| 193Ir | 77 | 116 | 192.9629264(18) | Observationally StableBelieved to undergo α decay to 189Re | 3/2+ | 0.627(2) | |||
| 193mIr | 80.240(6) keV | 10.53(4) d | IT | 193Ir | 11/2- | ||||
| 194Ir | 77 | 117 | 193.9650784(18) | 19.28(13) h | β- | 194Pt | 1- | ||
| 194m1Ir | 147.078(5) keV | 31.85(24) ms | IT | 194Ir | (4+) | ||||
| 194m2Ir | 370(70) keV | 171(11) d | (10,11)(-#) | ||||||
| 195Ir | 77 | 118 | 194.9659796(18) | 2.5(2) h | β- | 195Pt | 3/2+ | ||
| 195mIr | 100(5) keV | 3.8(2) h | β- (95%) | 195Pt | 11/2- | ||||
| IT (5%) | 195Ir | ||||||||
| 196Ir | 77 | 119 | 195.96840(4) | 52(1) s | β- | 196Pt | (0-) | ||
| 196mIr | 210(40) keV | 1.40(2) h | β- (99.7%) | 196Pt | (10,11-) | ||||
| IT | 196Ir | ||||||||
| 197Ir | 77 | 120 | 196.969653(22) | 5.8(5) min | β- | 197Pt | 3/2+ | ||
| 197mIr | 115(5) keV | 8.9(3) min | β- (99.75%) | 197Pt | 11/2- | ||||
| IT (.25%) | 197Ir | ||||||||
| 198Ir | 77 | 121 | 197.97228(21)# | 8(1) s | β- | 198Pt | |||
| 199Ir | 77 | 122 | 198.97380(4) | 20# s | β- | 199Pt | 3/2+# | ||
External links
- NLM Hazardous Substances Databank – Iridium, Radioactive (referring to iridium-192)