There are two natural isotopes of iridium (₇₇Ir), and 34 radioisotopes, the most stable radioisotope being ¹⁹²Ir with a half-life of 73.83 days, and many nuclear isomers, 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, 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 StableBelieved 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 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. 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 emitter, with a gamma dose-constant of approximately 1.54 μSv·h⁻¹· MBq⁻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 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. Radia ...

as a radiation source, in particular in brachytherapy. 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 operat ...

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