There are two natural

isotopes Isotopes are two or more types of atoms that have the same atomic number (number of protons in their nuclei) and position in the periodic table (and hence belong to the same chemical element), and that differ in nucleon numbers ( mass numbers ...

iridium Iridium is a chemical element with the symbol Ir and atomic number 77. A very hard, brittle, silvery-white transition metal of the platinum group, it is considered the second-densest naturally occurring metal (after osmium) with a density o ...

(₇₇Ir), and 34

radioisotope A radionuclide (radioactive nuclide, radioisotope or radioactive isotope) is a nuclide that has excess nuclear energy, making it unstable. This excess energy can be used in one of three ways: emitted from the nucleus as gamma radiation; transferr ...

s, the most stable radioisotope being ¹⁹²Ir with a

half-life Half-life (symbol ) is the time required for a quantity (of substance) to reduce to half of its initial value. The term is commonly used in nuclear physics to describe how quickly unstable atoms undergo radioactive decay or how long stable ...

of 73.83 days, and many

nuclear isomer A nuclear isomer is a metastable state of an atomic nucleus, in which one or more nucleons (protons or neutrons) occupy higher energy levels than in the ground state of the same nucleus. "Metastable" describes nuclei whose excited states have ...

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. All isotopes of iridium are either radioactive or

observationally stable Stable nuclides are nuclides that are not radioactive and so (unlike radionuclides) do not spontaneously undergo radioactive decay. When such nuclides are referred to in relation to specific elements, they are usually termed stable isotopes. Th ...

, meaning that they are predicted to be radioactive but no actual decay has been observed.

List of isotopes

, - , ¹⁶⁴Ir , style="text-align:right" , 77 , style="text-align:right" , 87 , 163.99220(44)# , 1# ms , , , 2−# , , , - , style="text-indent:1em" , ^164mIr , colspan="3" style="text-indent:2em" , 270(110)# keV , 94(27) µs , , , 9+# , , , - , rowspan=2, ¹⁶⁵Ir , rowspan=2 style="text-align:right" , 77 , rowspan=2 style="text-align:right" , 88 , rowspan=2, 164.98752(23)# , rowspan=2, 50# ns (<1 µs) , p , ¹⁶⁴Os , rowspan=2, 1/2+# , rowspan=2, , rowspan=2, , - , α (rare) , ¹⁶¹Re , - , rowspan=2 style="text-indent:1em" , ^165mIr , rowspan=2 colspan="3" style="text-indent:2em" , 180(50)# keV , rowspan=2, 300(60) µs , p (87%) , ¹⁶⁴Os , rowspan=2, 11/2− , rowspan=2, , rowspan=2, , - , α (13%) , ¹⁶¹Re , - , rowspan=2, ¹⁶⁶Ir , rowspan=2 style="text-align:right" , 77 , rowspan=2 style="text-align:right" , 89 , rowspan=2, 165.98582(22)# , rowspan=2, 10.5(22) ms , α (93%) , ¹⁶²Re , rowspan=2, (2−) , rowspan=2, , rowspan=2, , - , p (7%) , ¹⁶⁵Os , - , rowspan=2 style="text-indent:1em" , ^166mIr , rowspan=2 colspan="3" style="text-indent:2em" , 172(6) keV , rowspan=2, 15.1(9) ms , α (98.2%) , ¹⁶²Re , rowspan=2, (9+) , rowspan=2, , rowspan=2, , - , p (1.8%) , ¹⁶⁵Os , - , rowspan=3, ¹⁶⁷Ir , rowspan=3 style="text-align:right" , 77 , rowspan=3 style="text-align:right" , 90 , rowspan=3, 166.981665(20) , rowspan=3, 35.2(20) ms , α (48%) , ¹⁶³Re , rowspan=3, 1/2+ , rowspan=3, , rowspan=3, , - , p (32%) , ¹⁶⁶Os , - , β⁺ (20%) , ¹⁶⁷Os , - , rowspan=3 style="text-indent:1em" , ^167mIr , rowspan=3 colspan="3" style="text-indent:2em" , 175.3(22) keV , rowspan=3, 30.0(6) ms , α (80%) , ¹⁶³Re , rowspan=3, 11/2− , rowspan=3, , rowspan=3, , - , β⁺ (20%) , ¹⁶⁷Os , - , p (.4%) , ¹⁶⁶Os , - , rowspan=2, ¹⁶⁸Ir , rowspan=2 style="text-align:right" , 77 , rowspan=2 style="text-align:right" , 91 , rowspan=2, 167.97988(16)# , rowspan=2, 161(21) ms , α , ¹⁶⁴Re , rowspan=2, (2-) , rowspan=2, , rowspan=2, , - , β⁺ (rare) , ¹⁶⁸Os , - , style="text-indent:1em" , ^168mIr , colspan="3" style="text-indent:2em" , 50(100)# keV , 125(40) ms , α , ¹⁶⁴Re , (9+) , , , - , rowspan=2, ¹⁶⁹Ir , rowspan=2 style="text-align:right" , 77 , rowspan=2 style="text-align:right" , 92 , rowspan=2, 168.976295(28) , rowspan=2, 780(360) ms
.64(+46−24) s, α , ¹⁶⁵Re , rowspan=2, (1/2+) , rowspan=2, , rowspan=2, , - , β⁺ (rare) , ¹⁶⁹Os , - , rowspan=2 style="text-indent:1em" , ^169mIr , rowspan=2 colspan="3" style="text-indent:2em" , 154(24) keV , rowspan=2, 308(22) ms , α (72%) , ¹⁶⁵Re , rowspan=2, (11/2−) , rowspan=2, , rowspan=2, , - , β⁺ (28%) , ¹⁶⁹Os , - , rowspan=2, ¹⁷⁰Ir , rowspan=2 style="text-align:right" , 77 , rowspan=2 style="text-align:right" , 93 , rowspan=2, 169.97497(11)# , rowspan=2, 910(150) ms
.87(+18−12) s, β⁺ (64%) , ¹⁷⁰Os , rowspan=2, low# , rowspan=2, , rowspan=2, , - , α (36%) , ¹⁶⁶Re , - , rowspan=3 style="text-indent:1em" , ^170mIr , rowspan=3 colspan="3" style="text-indent:2em" , 160(50)# keV , rowspan=3, 440(60) ms , α (36%) , ¹⁶⁶Re , rowspan=3, (8+) , rowspan=3, , rowspan=3, , - , β⁺ , ¹⁷⁰Os , - , IT , ¹⁷⁰Ir , - , rowspan=2, ¹⁷¹Ir , rowspan=2 style="text-align:right" , 77 , rowspan=2 style="text-align:right" , 94 , rowspan=2, 170.97163(4) , rowspan=2, 3.6(10) s
.2(+13−7) s, α (58%) , ¹⁶⁷Re , rowspan=2, 1/2+ , rowspan=2, , rowspan=2, , - , β⁺ (42%) , ¹⁷¹Os , - , style="text-indent:1em" , ^171mIr , colspan="3" style="text-indent:2em" , 180(30)# keV , 1.40(10) s , , , (11/2−) , , , - , rowspan=2, ¹⁷²Ir , rowspan=2 style="text-align:right" , 77 , rowspan=2 style="text-align:right" , 95 , rowspan=2, 171.970610(30) , rowspan=2, 4.4(3) s , β⁺ (98%) , ¹⁷²Os , rowspan=2, (3+) , rowspan=2, , rowspan=2, , - , α (2%) , ¹⁶⁸Re , - , rowspan=2 style="text-indent:1em" , ^172mIr , rowspan=2 colspan="3" style="text-indent:2em" , 280(100)# keV , rowspan=2, 2.0(1) s , β⁺ (77%) , ¹⁷²Os , rowspan=2, (7+) , rowspan=2, , rowspan=2, , - , α (23%) , ¹⁶⁸Re , - , rowspan=2, ¹⁷³Ir , rowspan=2 style="text-align:right" , 77 , rowspan=2 style="text-align:right" , 96 , rowspan=2, 172.967502(15) , rowspan=2, 9.0(8) s , β⁺ (93%) , ¹⁷³Os , rowspan=2, (3/2+,5/2+) , rowspan=2, , rowspan=2, , - , α (7%) , ¹⁶⁹Re , - , rowspan=2 style="text-indent:1em" , ^173mIr , rowspan=2 colspan="3" style="text-indent:2em" , 253(27) keV , rowspan=2, 2.20(5) s , β⁺ (88%) , ¹⁷³Os , rowspan=2, (11/2−) , rowspan=2, , rowspan=2, , - , α (12%) , ¹⁶⁹Re , - , rowspan=2, ¹⁷⁴Ir , rowspan=2 style="text-align:right" , 77 , rowspan=2 style="text-align:right" , 97 , rowspan=2, 173.966861(30) , rowspan=2, 7.9(6) s , β⁺ (99.5%) , ¹⁷⁴Os , rowspan=2, (3+) , rowspan=2, , rowspan=2, , - , α (.5%) , ¹⁷⁰Re , - , rowspan=2 style="text-indent:1em" , ^174mIr , rowspan=2 colspan="3" style="text-indent:2em" , 193(11) keV , rowspan=2, 4.9(3) s , β⁺ (99.53%) , ¹⁷⁴Os , rowspan=2, (7+) , rowspan=2, , rowspan=2, , - , α (.47%) , ¹⁷⁰Re , - , rowspan=2, ¹⁷⁵Ir , rowspan=2 style="text-align:right" , 77 , rowspan=2 style="text-align:right" , 98 , rowspan=2, 174.964113(21) , rowspan=2, 9(2) s , β⁺ (99.15%) , ¹⁷⁵Os , rowspan=2, (5/2−) , rowspan=2, , rowspan=2, , - , α (.85%) , ¹⁷¹Re , - , rowspan=2, ¹⁷⁶Ir , rowspan=2 style="text-align:right" , 77 , rowspan=2 style="text-align:right" , 99 , rowspan=2, 175.963649(22) , rowspan=2, 8.3(6) s , β⁺ (97.9%) , ¹⁷⁶Os , rowspan=2, , rowspan=2, , rowspan=2, , - , α (2.1%) , ¹⁷²Re , - , rowspan=2, ¹⁷⁷Ir , rowspan=2 style="text-align:right" , 77 , rowspan=2 style="text-align:right" , 100 , rowspan=2, 176.961302(21) , rowspan=2, 30(2) s , β⁺ (99.94%) , ¹⁷⁷Os , rowspan=2, 5/2− , rowspan=2, , rowspan=2, , - , α (.06%) , ¹⁷³Re , - , ¹⁷⁸Ir , style="text-align:right" , 77 , style="text-align:right" , 101 , 177.961082(21) , 12(2) s , β⁺ , ¹⁷⁸Os , , , , - , ¹⁷⁹Ir , style="text-align:right" , 77 , style="text-align:right" , 102 , 178.959122(12) , 79(1) s , β⁺ , ¹⁷⁹Os , (5/2)− , , , - , ¹⁸⁰Ir , style="text-align:right" , 77 , style="text-align:right" , 103 , 179.959229(23) , 1.5(1) min , β⁺ , ¹⁸⁰Os , (4,5)(+#) , , , - , ¹⁸¹Ir , style="text-align:right" , 77 , style="text-align:right" , 104 , 180.957625(28) , 4.90(15) min , β⁺ , ¹⁸¹Os , (5/2)− , , , - , ¹⁸²Ir , style="text-align:right" , 77 , style="text-align:right" , 105 , 181.958076(23) , 15(1) min , β⁺ , ¹⁸²Os , (3+) , , , - , rowspan=2, ¹⁸³Ir , rowspan=2 style="text-align:right" , 77 , rowspan=2 style="text-align:right" , 106 , rowspan=2, 182.956846(27) , rowspan=2, 57(4) min , β⁺ ( 99.95%) , ¹⁸³Os , rowspan=2, 5/2− , rowspan=2, , rowspan=2, , - , α (.05%) , ¹⁷⁹Re , - , ¹⁸⁴Ir , style="text-align:right" , 77 , style="text-align:right" , 107 , 183.95748(3) , 3.09(3) h , β⁺ , ''¹⁸⁴Os'' , 5− , , , - , style="text-indent:1em" , ^184m1Ir , colspan="3" style="text-indent:2em" , 225.65(11) keV , 470(30) µs , , , 3+ , , , - , style="text-indent:1em" , ^184m2Ir , colspan="3" style="text-indent:2em" , 328.40(24) keV , 350(90) ns , , , (7)+ , , , - , ¹⁸⁵Ir , style="text-align:right" , 77 , style="text-align:right" , 108 , 184.95670(3) , 14.4(1) h , β⁺ , ¹⁸⁵Os , 5/2− , , , - , ¹⁸⁶Ir , style="text-align:right" , 77 , style="text-align:right" , 109 , 185.957946(18) , 16.64(3) h , β⁺ , ''¹⁸⁶Os'' , 5+ , , , - , rowspan=2 style="text-indent:1em" , ^186mIr , rowspan=2 colspan="3" style="text-indent:2em" , 0.8(4) keV , rowspan=2, 1.92(5) h , β⁺ , ''¹⁸⁶Os'' , rowspan=2, 2− , rowspan=2, , rowspan=2, , - , IT (rare) , ¹⁸⁶Ir , - , ¹⁸⁷Ir , style="text-align:right" , 77 , style="text-align:right" , 110 , 186.957363(7) , 10.5(3) h , β⁺ , ¹⁸⁷Os , 3/2+ , , , - , style="text-indent:1em" , ^187m1Ir , colspan="3" style="text-indent:2em" , 186.15(4) keV , 30.3(6) ms , IT , ¹⁸⁷Ir , 9/2− , , , - , style="text-indent:1em" , ^187m2Ir , colspan="3" style="text-indent:2em" , 433.81(9) keV , 152(12) ns , , , 11/2− , , , - , ¹⁸⁸Ir , style="text-align:right" , 77 , style="text-align:right" , 111 , 187.958853(8) , 41.5(5) h , β⁺ , ¹⁸⁸Os , 1− , , , - , rowspan=2 style="text-indent:1em" , ^188mIr , rowspan=2 colspan="3" style="text-indent:2em" , 970(30) keV , rowspan=2, 4.2(2) ms , IT , ¹⁸⁸Ir , rowspan=2, 7+# , rowspan=2, , rowspan=2, , - , β⁺ (rare) , ¹⁸⁸Os , - , ¹⁸⁹Ir , style="text-align:right" , 77 , style="text-align:right" , 112 , 188.958719(14) , 13.2(1) d , EC , ¹⁸⁹Os , 3/2+ , , , - , style="text-indent:1em" , ^189m1Ir , colspan="3" style="text-indent:2em" , 372.18(4) keV , 13.3(3) ms , IT , ¹⁸⁹Ir , 11/2− , , , - , style="text-indent:1em" , ^189m2Ir , colspan="3" style="text-indent:2em" , 2333.3(4) keV , 3.7(2) ms , , , (25/2)+ , , , - , ¹⁹⁰Ir , style="text-align:right" , 77 , style="text-align:right" , 113 , 189.9605460(18) , 11.78(10) d , β⁺ , ¹⁹⁰Os , 4− , , , - , style="text-indent:1em" , ^190m1Ir , colspan="3" style="text-indent:2em" , 26.1(1) keV , 1.120(3) h , IT , ¹⁹⁰Ir , (1−) , , , - , style="text-indent:1em" , ^190m2Ir , colspan="3" style="text-indent:2em" , 36.154(25) keV , >2 µs , , , (4)+ , , , - , style="text-indent:1em" , ^190m3Ir , colspan="3" style="text-indent:2em" , 376.4(1) keV , 3.087(12) h , , , (11)− , , , - , ¹⁹¹Ir , style="text-align:right" , 77 , style="text-align:right" , 114 , 190.9605940(18) , colspan=3 align=center,

Observationally Stable Stable nuclides are nuclides that are not radioactive and so (unlike radionuclides) do not spontaneously undergo radioactive decay. When such nuclides are referred to in relation to specific elements, they are usually termed stable isotopes. Th ...

Believed to undergo α decay to ''¹⁸⁷Re'' , 3/2+ , 0.373(2) , , - , style="text-indent:1em" , ^191m1Ir , colspan="3" style="text-indent:2em" , 171.24(5) keV , 4.94(3) s , IT , ¹⁹¹Ir , 11/2− , , , - , style="text-indent:1em" , ^191m2Ir , colspan="3" style="text-indent:2em" , 2120(40) keV , 5.5(7) s , , , , , , - , rowspan=2, ¹⁹²Ir , rowspan=2 style="text-align:right" , 77 , rowspan=2 style="text-align:right" , 115 , rowspan=2, 191.9626050(18) , rowspan=2, 73.827(13) d , β⁻ (95.24%) , ¹⁹²Pt , rowspan=2, 4+ , rowspan=2, , rowspan=2, , - , EC (4.76%) , ¹⁹²Os , - , style="text-indent:1em" , ^192m1Ir , colspan="3" style="text-indent:2em" , 56.720(5) keV , 1.45(5) min , , , 1− , , , - , style="text-indent:1em" , ^192m2Ir , colspan="3" style="text-indent:2em" , 168.14(12) keV , 241(9) y , , , (11−) , , , - , ¹⁹³Ir , style="text-align:right" , 77 , style="text-align:right" , 116 , 192.9629264(18) , colspan=3 align=center, Observationally StableBelieved to undergo α decay to ¹⁸⁹Re , 3/2+ , 0.627(2) , , - , style="text-indent:1em" , ^193mIr , colspan="3" style="text-indent:2em" , 80.240(6) keV , 10.53(4) d , IT , ¹⁹³Ir , 11/2− , , , - , ¹⁹⁴Ir , style="text-align:right" , 77 , style="text-align:right" , 117 , 193.9650784(18) , 19.28(13) h , β⁻ , ¹⁹⁴Pt , 1− , , , - , style="text-indent:1em" , ^194m1Ir , colspan="3" style="text-indent:2em" , 147.078(5) keV , 31.85(24) ms , IT , ¹⁹⁴Ir , (4+) , , , - , style="text-indent:1em" , ^194m2Ir , colspan="3" style="text-indent:2em" , 370(70) keV , 171(11) d , , , (10,11)(−#) , , , - , ¹⁹⁵Ir , style="text-align:right" , 77 , style="text-align:right" , 118 , 194.9659796(18) , 2.5(2) h , β⁻ , ¹⁹⁵Pt , 3/2+ , , , - , rowspan=2 style="text-indent:1em" , ^195mIr , rowspan=2 colspan="3" style="text-indent:2em" , 100(5) keV , rowspan=2, 3.8(2) h , β⁻ (95%) , ¹⁹⁵Pt , rowspan=2, 11/2− , rowspan=2, , rowspan=2, , - , IT (5%) , ¹⁹⁵Ir , - , ¹⁹⁶Ir , style="text-align:right" , 77 , style="text-align:right" , 119 , 195.96840(4) , 52(1) s , β⁻ , ¹⁹⁶Pt , (0−) , , , - , rowspan=2 style="text-indent:1em" , ^196mIr , rowspan=2 colspan="3" style="text-indent:2em" , 210(40) keV , rowspan=2, 1.40(2) h , β⁻ (99.7%) , ¹⁹⁶Pt , rowspan=2, (10,11−) , rowspan=2, , rowspan=2, , - , IT , ¹⁹⁶Ir , - , ¹⁹⁷Ir , style="text-align:right" , 77 , style="text-align:right" , 120 , 196.969653(22) , 5.8(5) min , β⁻ , ¹⁹⁷Pt , 3/2+ , , , - , rowspan=2 style="text-indent:1em" , ^197mIr , rowspan=2 colspan="3" style="text-indent:2em" , 115(5) keV , rowspan=2, 8.9(3) min , β⁻ (99.75%) , ¹⁹⁷Pt , rowspan=2, 11/2− , rowspan=2, , rowspan=2, , - , IT (.25%) , ¹⁹⁷Ir , - , ¹⁹⁸Ir , style="text-align:right" , 77 , style="text-align:right" , 121 , 197.97228(21)# , 8(1) s , β⁻ , ¹⁹⁸Pt , , , , - , ¹⁹⁹Ir , style="text-align:right" , 77 , style="text-align:right" , 122 , 198.97380(4) , 7(5) s , β⁻ , ¹⁹⁹Pt , 3/2+# , , , - , style="text-indent:1em" , ^199mIr , colspan="3" style="text-indent:2em" , 130(40)# keV , 235(90) ns , IT , ¹⁹⁹Ir , 11/2−# , , , - , ²⁰⁰Ir , style="text-align:right" , 77 , style="text-align:right" , 123 , 199.976800(210)# , 43(6) s , β⁻ , ²⁰⁰Pt , (2-, 3-) , , , - , ²⁰¹Ir , style="text-align:right" , 77 , style="text-align:right" , 124 , 200.978640(210)# , 21(5) s , β⁻ , ²⁰¹Pt , (3/2+) , , , - , ²⁰²Ir , style="text-align:right" , 77 , style="text-align:right" , 125 , 201.981990(320)# , 11(3) s , β⁻ , ²⁰²Pt , (2-) , , , - , style="text-indent:1em" , ^202mIr , colspan="3" style="text-indent:2em" , 2000(1000)# keV , 3.4(0.6) µs , IT , ²⁰²Ir , , ,

Iridium-192

Iridium-192 (symbol ¹⁹²Ir) is a radioactive

isotope Isotopes are two or more types of atoms that have the same atomic number (number of protons in their nuclei) and position in the periodic table (and hence belong to the same chemical element), and that differ in nucleon numbers ( mass num ...

, with a

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. Some of the β particles are 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 normally produced by neutron activation of natural-abundance iridium metal. Iridium-192 is a very strong

gamma ray A gamma ray, also known as gamma radiation (symbol γ or \gamma), is a penetrating form of electromagnetic radiation arising from the radioactive decay of atomic nuclei. It consists of the shortest wavelength electromagnetic waves, typically ...

emitter, with a gamma dose-constant of approximately 1.54 μSv·h⁻¹·

MBq ''MBQ'' is an original English-language manga created by Tokyopop's Rising Stars of Manga second-place winner Felipe Smith. ''MBQ'' is an expansion of his second-place winning entry in the third Rising Stars competition. It is the story of a y ...

⁻¹ at 30 cm, and a specific activity of 341 TBq·g⁻¹ (9.22 kCi·g⁻¹). 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 is a modality of non-destructive testing that uses ionizing radiation to inspect materials and components with the objective of locating and quantifying defects and degradation in material properties that would lead to the ...

to locate flaws in metal components. It is also used in

radiotherapy Radiation therapy or radiotherapy, often abbreviated RT, RTx, or XRT, is a therapy using ionizing radiation, generally provided as part of cancer treatment to control or kill malignant cells and normally delivered by a linear accelerator. Rad ...

as a radiation source, in particular in

brachytherapy Brachytherapy is a form of radiation therapy where a sealed radiation source is placed inside or next to the area requiring treatment. ''Brachy'' is Greek for short. Brachytherapy is commonly used as an effective treatment for cervical, pro ...

. Iridium-192 has accounted for the majority of cases tracked by the U.S

Nuclear Regulatory Commission The Nuclear Regulatory Commission (NRC) is an independent agency of the United States government tasked with protecting public health and safety related to nuclear energy. Established by the Energy Reorganization Act of 1974, the NRC began opera ...

in which radioactive materials have gone missing in quantities large enough to make a

dirty bomb A dirty bomb or radiological dispersal device is a radiological weapon that combines radioactive material with conventional explosives. The purpose of the weapon is to contaminate the area around the dispersal agent/conventional explosion with ...

. The ^192m2Ir isomer is unusual, both for its long half-life for an isomer, and that said half-life greatly exceeds that of the ground state of the same isotope.

References

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

External links

NLM Hazardous Substances Databank – Iridium, Radioactive
(referring to iridium-192) {{Navbox element isotopes Iridium

Iridium Iridium is a chemical element with the symbol Ir and atomic number 77. A very hard, brittle, silvery-white transition metal of the platinum group, it is considered the second-densest naturally occurring metal (after osmium) with a density o ...