# Isotopes of iridium

There are two natural isotopes of iridium ($_{77}$Ir), and 37 radioisotopes, the most stable radioisotope being $^{192}$Ir with a half-life of 73.83 days, and many nuclear isomers, the most stable of which is $^{192m2}$Ir 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

| Nuclide | Z | N | Isotopic mass (Da) | Half-life | Decay mode | Daughter isotope | Spin and parity | Natural abundance (mole fraction) | Natural abundance (mole fraction) |
| Nuclide | Excitation energy | Excitation energy | Excitation energy | Half-life | Decay mode | Daughter isotope | Spin and parity | Normal proportion | Range of variation |
| $^{164}$Ir | 77 | 87 | 163.99220(44)# | <0.5 μs | p? | $^{163}$Os | 2−# | | |
| $^{164m}$Ir | 270(110)# keV | 270(110)# keV | 270(110)# keV | 70(10) μs | p (96%) | $^{163}$Os | 9+# | | |
| $^{164m}$Ir | 270(110)# keV | 270(110)# keV | 270(110)# keV | 70(10) μs | α (4%) | $^{160m}$Re | 9+# | | |
| $^{165}$Ir | 77 | 88 | 164.98752(23)# | 1.20+0.82 −0.74 μs | p | $^{164}$Os | (1/2+) | | |
| $^{165m}$Ir | ~255 keV | ~255 keV | ~255 keV | 340(40) μs | p (88%) | $^{164}$Os | (11/2−) | | |
| $^{165m}$Ir | ~255 keV | ~255 keV | ~255 keV | 340(40) μs | α (12%) | $^{161m}$Re | (11/2−) | | |
| $^{166}$Ir | 77 | 89 | 165.98582(22)# | 10.5(22) ms | α (93%) | $^{162}$Re | (2−) | | |
| $^{166}$Ir | 77 | 89 | 165.98582(22)# | 10.5(22) ms | p (7%) | $^{165}$Os | (2−) | | |
| $^{166m}$Ir | 172(6) keV | 172(6) keV | 172(6) keV | 15.1(9) ms | α (98.2%) | $^{162}$Re | (9+) | | |
| $^{166m}$Ir | 172(6) keV | 172(6) keV | 172(6) keV | 15.1(9) ms | p (1.8%) | $^{165}$Os | (9+) | | |
| $^{167}$Ir | 77 | 90 | 166.981665(20) | 35.2(20) ms | α (48%) | $^{163}$Re | 1/2+ | | |
| $^{167}$Ir | 77 | 90 | 166.981665(20) | 35.2(20) ms | p (32%) | $^{166}$Os | 1/2+ | | |
| $^{167}$Ir | 77 | 90 | 166.981665(20) | 35.2(20) ms | β$^+$ (20%) | $^{167}$Os | 1/2+ | | |
| $^{167m}$Ir | 175.3(22) keV | 175.3(22) keV | 175.3(22) keV | 30.0(6) ms | α (80%) | $^{163}$Re | 11/2− | | |
| $^{167m}$Ir | 175.3(22) keV | 175.3(22) keV | 175.3(22) keV | 30.0(6) ms | β$^+$ (20%) | $^{167}$Os | 11/2− | | |
| $^{167m}$Ir | 175.3(22) keV | 175.3(22) keV | 175.3(22) keV | 30.0(6) ms | p (.4%) | $^{166}$Os | 11/2− | | |
| $^{168}$Ir | 77 | 91 | 167.97988(16)# | 161(21) ms | α | $^{164}$Re | (2-) | | |
| $^{168}$Ir | 77 | 91 | 167.97988(16)# | 161(21) ms | β$^+$ (rare) | $^{168}$Os | (2-) | | |
| $^{168m}$Ir | 50(100)# keV | 50(100)# keV | 50(100)# keV | 125(40) ms | α | $^{164}$Re | (9+) | | |
| $^{169}$Ir | 77 | 92 | 168.976295(28) | 780(360) ms [640+460 −240 ms] | α | $^{165}$Re | (1/2+) | | |
| $^{169}$Ir | 77 | 92 | 168.976295(28) | 780(360) ms [640+460 −240 ms] | β$^+$ (rare) | $^{169}$Os | (1/2+) | | |
| $^{169m}$Ir | 154(24) keV | 154(24) keV | 154(24) keV | 308(22) ms | α (72%) | $^{165}$Re | (11/2−) | | |
| $^{169m}$Ir | 154(24) keV | 154(24) keV | 154(24) keV | 308(22) ms | β$^+$ (28%) | $^{169}$Os | (11/2−) | | |
| $^{170}$Ir | 77 | 93 | 169.97497(11)# | 910(150) ms [870+180 −120 ms] | β$^+$ (64%) | $^{170}$Os | low# | | |
| $^{170}$Ir | 77 | 93 | 169.97497(11)# | 910(150) ms [870+180 −120 ms] | α (36%) | $^{166}$Re | low# | | |
| $^{170m}$Ir | 160(50)# keV | 160(50)# keV | 160(50)# keV | 440(60) ms | α (36%) | $^{166}$Re | (8+) | | |
| $^{170m}$Ir | 160(50)# keV | 160(50)# keV | 160(50)# keV | 440(60) ms | β$^+$ | $^{170}$Os | (8+) | | |
| $^{170m}$Ir | 160(50)# keV | 160(50)# keV | 160(50)# keV | 440(60) ms | IT | $^{170}$Ir | (8+) | | |
| $^{171}$Ir | 77 | 94 | 170.97163(4) | 3.6(10) s [3.2+13 −7 s] | α (58%) | $^{167}$Re | 1/2+ | | |
| $^{171}$Ir | 77 | 94 | 170.97163(4) | 3.6(10) s [3.2+13 −7 s] | β$^+$ (42%) | $^{171}$Os | 1/2+ | | |
| $^{171m}$Ir | 180(30)# keV | 180(30)# keV | 180(30)# keV | 1.40(10) s | | | (11/2−) | | |
| $^{172}$Ir | 77 | 95 | 171.970610(30) | 4.4(3) s | β$^+$ (98%) | $^{172}$Os | (3+) | | |
| $^{172}$Ir | 77 | 95 | 171.970610(30) | 4.4(3) s | α (2%) | $^{168}$Re | (3+) | | |
| $^{172m}$Ir | 280(100)# keV | 280(100)# keV | 280(100)# keV | 2.0(1) s | β$^+$ (77%) | $^{172}$Os | (7+) | | |
| $^{172m}$Ir | 280(100)# keV | 280(100)# keV | 280(100)# keV | 2.0(1) s | α (23%) | $^{168}$Re | (7+) | | |
| $^{173}$Ir | 77 | 96 | 172.967502(15) | 9.0(8) s | β$^+$ (93%) | $^{173}$Os | (3/2+,5/2+) | | |
| $^{173}$Ir | 77 | 96 | 172.967502(15) | 9.0(8) s | α (7%) | $^{169}$Re | (3/2+,5/2+) | | |
| $^{173m}$Ir | 253(27) keV | 253(27) keV | 253(27) keV | 2.20(5) s | β$^+$ (88%) | $^{173}$Os | (11/2−) | | |
| $^{173m}$Ir | 253(27) keV | 253(27) keV | 253(27) keV | 2.20(5) s | α (12%) | $^{169}$Re | (11/2−) | | |
| $^{174}$Ir | 77 | 97 | 173.966861(30) | 7.9(6) s | β$^+$ (99.5%) | $^{174}$Os | (3+) | | |
| $^{174}$Ir | 77 | 97 | 173.966861(30) | 7.9(6) s | α (.5%) | $^{170}$Re | (3+) | | |
| $^{174m}$Ir | 193(11) keV | 193(11) keV | 193(11) keV | 4.9(3) s | β$^+$ (99.53%) | $^{174}$Os | (7+) | | |
| $^{174m}$Ir | 193(11) keV | 193(11) keV | 193(11) keV | 4.9(3) s | α (.47%) | $^{170}$Re | (7+) | | |
| $^{175}$Ir | 77 | 98 | 174.964113(21) | 9(2) s | β$^+$ (99.15%) | $^{175}$Os | (5/2−) | | |
| $^{175}$Ir | 77 | 98 | 174.964113(21) | 9(2) s | α (.85%) | $^{171}$Re | (5/2−) | | |
| $^{176}$Ir | 77 | 99 | 175.963649(22) | 8.3(6) s | β$^+$ (97.9%) | $^{176}$Os | | | |
| $^{176}$Ir | 77 | 99 | 175.963649(22) | 8.3(6) s | α (2.1%) | $^{172}$Re | | | |
| $^{177}$Ir | 77 | 100 | 176.961302(21) | 30(2) s | β$^+$ (99.94%) | $^{177}$Os | 5/2− | | |
| $^{177}$Ir | 77 | 100 | 176.961302(21) | 30(2) s | α (.06%) | $^{173}$Re | 5/2− | | |
| $^{178}$Ir | 77 | 101 | 177.961082(21) | 12(2) s | β$^+$ | $^{178}$Os | | | |
| $^{179}$Ir | 77 | 102 | 178.959122(12) | 79(1) s | β$^+$ | $^{179}$Os | (5/2)− | | |
| $^{180}$Ir | 77 | 103 | 179.959229(23) | 1.5(1) min | β$^+$ | $^{180}$Os | (4,5)(+#) | | |
| $^{181}$Ir | 77 | 104 | 180.957625(28) | 4.90(15) min | β$^+$ | $^{181}$Os | (5/2)− | | |
| $^{182}$Ir | 77 | 105 | 181.958076(23) | 15(1) min | β$^+$ | $^{182}$Os | (3+) | | |
| $^{183}$Ir | 77 | 106 | 182.956846(27) | 57(4) min | β$^+$ ( 99.95%) | $^{183}$Os | 5/2− | | |
| $^{183}$Ir | 77 | 106 | 182.956846(27) | 57(4) min | α (.05%) | $^{179}$Re | 5/2− | | |
| $^{184}$Ir | 77 | 107 | 183.95748(3) | 3.09(3) h | β$^+$ | $^{184}$Os | 5− | | |
| $^{184m1}$Ir | 225.65(11) keV | 225.65(11) keV | 225.65(11) keV | 470(30) μs | | | 3+ | | |
| $^{184m2}$Ir | 328.40(24) keV | 328.40(24) keV | 328.40(24) keV | 350(90) ns | | | (7)+ | | |
| $^{185}$Ir | 77 | 108 | 184.95670(3) | 14.4(1) h | β$^+$ | $^{185}$Os | 5/2− | | |
| $^{186}$Ir | 77 | 109 | 185.957946(18) | 16.64(3) h | β$^+$ | $^{186}$Os | 5+ | | |
| $^{186m}$Ir | 0.8(4) keV | 0.8(4) keV | 0.8(4) keV | 1.92(5) h | β$^+$ | $^{186}$Os | 2− | | |
| $^{186m}$Ir | 0.8(4) keV | 0.8(4) keV | 0.8(4) keV | 1.92(5) h | IT (rare) | $^{186}$Ir | 2− | | |
| $^{187}$Ir | 77 | 110 | 186.957363(7) | 10.5(3) h | β$^+$ | $^{187}$Os | 3/2+ | | |
| $^{187m1}$Ir | 186.15(4) keV | 186.15(4) keV | 186.15(4) keV | 30.3(6) ms | IT | $^{187}$Ir | 9/2− | | |
| $^{187m2}$Ir | 433.81(9) keV | 433.81(9) keV | 433.81(9) keV | 152(12) ns | | | 11/2− | | |
| $^{188}$Ir | 77 | 111 | 187.958853(8) | 41.5(5) h | β$^+$ | $^{188}$Os | 1− | | |
| $^{188m}$Ir | 970(30) keV | 970(30) keV | 970(30) keV | 4.2(2) ms | IT | $^{188}$Ir | 7+# | | |
| $^{188m}$Ir | 970(30) keV | 970(30) keV | 970(30) keV | 4.2(2) ms | β$^+$ (rare) | $^{188}$Os | 7+# | | |
| $^{189}$Ir | 77 | 112 | 188.958719(14) | 13.2(1) d | EC | $^{189}$Os | 3/2+ | | |
| $^{189m1}$Ir | 372.18(4) keV | 372.18(4) keV | 372.18(4) keV | 13.3(3) ms | IT | $^{189}$Ir | 11/2− | | |
| $^{189m2}$Ir | 2333.3(4) keV | 2333.3(4) keV | 2333.3(4) keV | 3.7(2) ms | | | (25/2)+ | | |
| $^{190}$Ir | 77 | 113 | 189.9605460(18) | 11.7511(20) d | EC | $^{190}$Os | 4− | |
| $^{190}$Ir | 77 | 113 | 189.9605460(18) | 11.7511(20) d | β$^+$ (<0.002%) | $^{190}$Os | 4− | |
| $^{190m1}$Ir | 26.1(1) keV | 26.1(1) keV | 26.1(1) keV | 1.120(3) h | IT | $^{190}$Ir | (1)− | | |
| $^{190m2}$Ir | 36.154(25) keV | 36.154(25) keV | 36.154(25) keV | >2 μs | | | (4)+ | | |
| $^{190m3}$Ir | 376.4(1) keV | 376.4(1) keV | 376.4(1) keV | 3.087(12) h | EC (91.4%) | $^{190}$Os | (11)− | | |
| $^{190m3}$Ir | 376.4(1) keV | 376.4(1) keV | 376.4(1) keV | 3.087(12) h | IT (8.6%) | $^{190}$Ir | (11)− | | |
| $^{191}$Ir | 77 | 114 | 190.9605940(18) | Observationally Stable | Observationally Stable | Observationally Stable | 3/2+ | 0.373(2) | |
| $^{191m1}$Ir | 171.24(5) keV | 171.24(5) keV | 171.24(5) keV | 4.94(3) s | IT | $^{191}$Ir | 11/2− | | |
| $^{191m2}$Ir | 2120(40) keV | 2120(40) keV | 2120(40) keV | 5.5(7) s | | | | | |
| $^{192}$Ir | 77 | 115 | 191.9626050(18) | 73.827(13) d | β$^−$ (95.24%) | $^{192}$Pt | 4+ | | |
| $^{192}$Ir | 77 | 115 | 191.9626050(18) | 73.827(13) d | EC (4.76%) | $^{192}$Os | 4+ | | |
| $^{192m1}$Ir | 56.720(5) keV | 56.720(5) keV | 56.720(5) keV | 1.45(5) min | IT (98.25%) | $^{192}$Ir | 1− | | |
| $^{192m1}$Ir | 56.720(5) keV | 56.720(5) keV | 56.720(5) keV | 1.45(5) min | β$^−$ (1.75%) | $^{192}$Pt | 1− | | |
| $^{192m2}$Ir | 168.14(12) keV | 168.14(12) keV | 168.14(12) keV | 241(9) y | IT | $^{192}$Ir | (11−) | | |
| $^{193}$Ir | 77 | 116 | 192.9629264(18) | Observationally Stable | Observationally Stable | Observationally Stable | 3/2+ | 0.627(2) | |
| $^{193m}$Ir | 80.240(6) keV | 80.240(6) keV | 80.240(6) keV | 10.53(4) d | IT | $^{193}$Ir | 11/2− | | |
| $^{194}$Ir | 77 | 117 | 193.9650784(18) | 19.28(13) h | β$^−$ | $^{194}$Pt | 1− | | |
| $^{194m1}$Ir | 147.078(5) keV | 147.078(5) keV | 147.078(5) keV | 31.85(24) ms | IT | $^{194}$Ir | (4+) | | |
| $^{194m2}$Ir | 370(70) keV | 370(70) keV | 370(70) keV | 171(11) d | | | (10,11)(−#) | | |
| $^{195}$Ir | 77 | 118 | 194.9659796(18) | 2.5(2) h | β$^−$ | $^{195}$Pt | 3/2+ | | |
| $^{195m}$Ir | 100(5) keV | 100(5) keV | 100(5) keV | 3.8(2) h | β$^−$ (95%) | $^{195}$Pt | 11/2− | | |
| $^{195m}$Ir | 100(5) keV | 100(5) keV | 100(5) keV | 3.8(2) h | IT (5%) | $^{195}$Ir | 11/2− | | |
| $^{196}$Ir | 77 | 119 | 195.96840(4) | 52(1) s | β$^−$ | $^{196}$Pt | (0−) | | |
| $^{196m}$Ir | 210(40) keV | 210(40) keV | 210(40) keV | 1.40(2) h | β$^−$ (99.7%) | $^{196}$Pt | (10,11−) | | |
| $^{196m}$Ir | 210(40) keV | 210(40) keV | 210(40) keV | 1.40(2) h | IT | $^{196}$Ir | (10,11−) | | |
| $^{197}$Ir | 77 | 120 | 196.969653(22) | 5.8(5) min | β$^−$ | $^{197}$Pt | 3/2+ | | |
| $^{197m}$Ir | 115(5) keV | 115(5) keV | 115(5) keV | 8.9(3) min | β$^−$ (99.75%) | $^{197}$Pt | 11/2− | | |
| $^{197m}$Ir | 115(5) keV | 115(5) keV | 115(5) keV | 8.9(3) min | IT (.25%) | $^{197}$Ir | 11/2− | | |
| $^{198}$Ir | 77 | 121 | 197.97228(21)# | 8(1) s | β$^−$ | $^{198}$Pt | | | |
| $^{199}$Ir | 77 | 122 | 198.97380(4) | 7(5) s | β$^−$ | $^{199}$Pt | 3/2+# | | |
| $^{199m}$Ir | 130(40)# keV | 130(40)# keV | 130(40)# keV | 235(90) ns | IT | $^{199}$Ir | 11/2−# | | |
| $^{200}$Ir | 77 | 123 | 199.976800(210)# | 43(6) s | β$^−$ | $^{200}$Pt | (2-, 3-) | | |
| $^{201}$Ir | 77 | 124 | 200.978640(210)# | 21(5) s | β$^−$ | $^{201}$Pt | (3/2+) | | |
| $^{202}$Ir | 77 | 125 | 201.981990(320)# | 11(3) s | β$^−$ | $^{202}$Pt | (2-) | | |
| $^{202m}$Ir | 2000(1000)# keV | 2000(1000)# keV | 2000(1000)# keV | 3.4(0.6) μs | IT | $^{202}$Ir | | | |
| This table header & footer: view ||||||||||
* ↑ $^m$Ir – Excited nuclear isomer.
* ↑ ( ) – Uncertainty (1σ) is given in concise form in parentheses after the corresponding last digits.
* ↑ # – Atomic mass marked #: value and uncertainty derived not from purely experimental data, but at least partly from trends from the Mass Surface (TMS).
* 1 2 3 # – Values marked # are not purely derived from experimental data, but at least partly from trends of neighboring nuclides (TNN).
* ↑ Modes of decay: EC:Electron capture IT:Isomeric transition p:Proton emission
* ↑ Bold italics symbol as daughter – Daughter product is nearly stable.
* ↑ Bold symbol as daughter – Daughter product is stable.
* ↑ ( ) spin value – Indicates spin with weak assignment arguments.
* ↑ Believed to undergo α decay to $^{187}$Re
* ↑ Believed to undergo α decay to $^{189}$Re

## Iridium-192

Iridium-192 (symbol $^{192}$Ir) 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 $^{192}$Ir decays occur via emission of β and γ radiation, leading to $^{192}$Pt. Some of the β particles are captured by other $^{192}$Ir nuclei, which are then converted to $^{192}$Os. Electron capture is responsible for the remaining 4% of $^{192}$Ir 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.
The $^{192m2}$Ir 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.