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

1. Ir – Excited nuclear isomer.
2. ( ) – Uncertainty (1σ) is given in concise form in parentheses after the corresponding last digits.
3. # – Atomic mass marked #: value and uncertainty derived not from purely experimental data, but at least partly from trends from the Mass Surface (TMS).
4. ^ # – Values marked # are not purely derived from experimental data, but at least partly from trends of neighboring nuclides (TNN).
5. Modes of decay:

   EC:	Electron capture
   IT:	Isomeric transition
   p:	Proton emission

6. Bold italics symbol as daughter – Daughter product is nearly stable.
7. Bold symbol as daughter – Daughter product is stable.
8. ( ) spin value – Indicates spin with weak assignment arguments.
9. Believed to undergo α decay to Re
10. Believed to undergo α decay to Re

Iridium-192

Iridium-192 (symbol 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 Ir decays occur via emission of β and γ radiation, leading to Pt. Some of the β particles are captured by other Ir nuclei, which are then converted to Os. Electron capture is responsible for the remaining 4% of 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·MBq at 30 cm, and a specific activity of 341 TBq·g (9.22 kCi·g). There are seven principal energy packets produced during its disintegration process ranging from just over 0.2 to about 0.6 MeV.

The 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.

References

1. Kondev, F. G.; Wang, M.; Huang, W. J.; Naimi, S.; Audi, G. (2021). "The NUBASE2020 evaluation of nuclear properties" (PDF). Chinese Physics C. 45 (3): 030001. doi:10.1088/1674-1137/abddae.
2. "Standard Atomic Weights: Iridium". CIAAW. 2017.
3. Prohaska, Thomas; Irrgeher, Johanna; Benefield, Jacqueline; Böhlke, John K.; Chesson, Lesley A.; Coplen, Tyler B.; Ding, Tiping; Dunn, Philip J. H.; Gröning, Manfred; Holden, Norman E.; Meijer, Harro A. J. (2022-05-04). "Standard atomic weights of the elements 2021 (IUPAC Technical Report)". Pure and Applied Chemistry. doi:10.1515/pac-2019-0603. ISSN 1365-3075.
4. Belli, P.; Bernabei, R.; Danevich, F. A.; et al. (2019). "Experimental searches for rare alpha and beta decays". European Physical Journal A. 55 (8): 140–1–140–7. arXiv:1908.11458. Bibcode:2019EPJA...55..140B. doi:10.1140/epja/i2019-12823-2. ISSN 1434-601X. S2CID 201664098.
5. Half-life, decay mode, nuclear spin, and isotopic composition is sourced in:
   Audi, G.; Kondev, F. G.; Wang, M.; Huang, W. J.; Naimi, S. (2017). "The NUBASE2016 evaluation of nuclear properties" (PDF). Chinese Physics C. 41 (3): 030001. Bibcode:2017ChPhC..41c0001A. doi:10.1088/1674-1137/41/3/030001.
6. Wang, M.; Audi, G.; Kondev, F. G.; Huang, W. J.; Naimi, S.; Xu, X. (2017). "The AME2016 atomic mass evaluation (II). Tables, graphs, and references" (PDF). Chinese Physics C. 41 (3): 030003-1–030003-442. doi:10.1088/1674-1137/41/3/030003.
7. Drummond, M. C.; O'Donnell, D.; Page, R. D.; Joss, D. T.; Capponi, L.; Cox, D. M.; Darby, I. G.; Donosa, L.; Filmer, F.; Grahn, T.; Greenlees, P. T.; Hauschild, K.; Herzan, A.; Jakobsson, U.; Jones, P. M.; Julin, R.; Juutinen, S.; Ketelhut, S.; Leino, M.; Lopez-Martens, A.; Mistry, A. K.; Nieminen, P.; Peura, P.; Rahkila, P.; Rinta-Antila, S.; Ruotsalainen, P.; Sandzelius, M.; Sarén, J.; Sayğı, B.; Scholey, C.; Simpson, J.; Sorri, J.; Thornthwaite, A.; Uusitalo, J. (16 June 2014). "α decay of the π h 11 / 2 isomer in Ir 164". Physical Review C. 89 (6): 064309. Bibcode:2014PhRvC..89f4309D. doi:10.1103/PhysRevC.89.064309. ISSN 0556-2813. Retrieved 21 June 2023.
8. Hilton, Joshua Ben. "Decays of new nuclides 169Au, 170Hg, 165Pt and the ground state of 165Ir discovered using MARA". University of Liverpool. ProQuest 2448649087. Retrieved 21 June 2023.
9. Drummond, M. C.; O'Donnell, D.; Page, R. D.; Joss, D. T.; Capponi, L.; Cox, D. M.; Darby, I. G.; Donosa, L.; Filmer, F.; Grahn, T.; Greenlees, P. T.; Hauschild, K.; Herzan, A.; Jakobsson, U.; Jones, P. M.; Julin, R.; Juutinen, S.; Ketelhut, S.; Leino, M.; Lopez-Martens, A.; Mistry, A. K.; Nieminen, P.; Peura, P.; Rahkila, P.; Rinta-Antila, S.; Ruotsalainen, P.; Sandzelius, M.; Sarén, J.; Sayğı, B.; Scholey, C.; Simpson, J.; Sorri, J.; Thornthwaite, A.; Uusitalo, J. (16 June 2014). "α decay of the π h 11 / 2 isomer in Ir 164". Physical Review C. 89 (6): 064309. Bibcode:2014PhRvC..89f4309D. doi:10.1103/PhysRevC.89.064309. ISSN 0556-2813. Retrieved 21 June 2023.
10. ^ Janiak, Ł.; Gierlik, M.; Kosinski, T.; Matusiak, M.; Madejowski, G.; Wronka, S.; Rzadkiewicz, J. (2024). "Half-life of Ir". Physical Review C. 110 (014306). doi:10.1103/PhysRevC.110.014306.
11. "Radioisotope Brief: Iridium-192 (Ir-192)". Retrieved 20 March 2012.
12. Baggerly, Leo L. (1956). The radioactive decay of Iridium-192 (PDF) (Ph.D. thesis). Pasadena, Calif.: California Institute of Technology. pp. 1, 2, 7. doi:10.7907/26VA-RB25.
13. "Isotope Supplier: Stable Isotopes and Radioisotopes from ISOFLEX - Iridium-192". www.isoflex.com. Retrieved 2017-10-11.
14. Delacroix, D; Guerre, J P; Leblanc, P; Hickman, C (2002). Radionuclide and Radiation Protection Data Handbook (PDF). Radiation Protection Dosimetry. Vol. 98, no. 1 (2nd ed.). Ashford, Kent: Nuclear Technology Publishing. pp. 9–168. doi:10.1093/OXFORDJOURNALS.RPD.A006705. ISBN 1870965876. PMID 11916063. S2CID 123447679. Archived from the original (PDF) on 2019-08-22.
15. Unger, L M; Trubey, D K (May 1982). Specific Gamma-Ray Dose Constants for Nuclides Important to Dosimetry and Radiological Assessment (PDF) (Report). Oak Ridge National Laboratory. Archived from the original (PDF) on 22 March 2018.

• Isotope masses from:
  • Audi, Georges; Bersillon, Olivier; Blachot, Jean; Wapstra, Aaldert Hendrik (2003), "The NUBASE evaluation of nuclear and decay properties", Nuclear Physics A, 729: 3–128, Bibcode:2003NuPhA.729....3A, doi:10.1016/j.nuclphysa.2003.11.001
• Isotopic compositions and standard atomic masses from:
  • de Laeter, John Robert; Böhlke, John Karl; De Bièvre, Paul; Hidaka, Hiroshi; Peiser, H. Steffen; Rosman, Kevin J. R.; Taylor, Philip D. P. (2003). "Atomic weights of the elements. Review 2000 (IUPAC Technical Report)". Pure and Applied Chemistry. 75 (6): 683–800. doi:10.1351/pac200375060683.
  • Wieser, Michael E. (2006). "Atomic weights of the elements 2005 (IUPAC Technical Report)". Pure and Applied Chemistry. 78 (11): 2051–2066. doi:10.1351/pac200678112051.
• "News & Notices: Standard Atomic Weights Revised". International Union of Pure and Applied Chemistry. 19 October 2005.
• Half-life, spin, and isomer data selected from the following sources.
  • Audi, Georges; Bersillon, Olivier; Blachot, Jean; Wapstra, Aaldert Hendrik (2003), "The NUBASE evaluation of nuclear and decay properties", Nuclear Physics A, 729: 3–128, Bibcode:2003NuPhA.729....3A, doi:10.1016/j.nuclphysa.2003.11.001
  • National Nuclear Data Center. "NuDat 2.x database". Brookhaven National Laboratory.
  • Holden, Norman E. (2004). "11. Table of the Isotopes". In Lide, David R. (ed.). CRC Handbook of Chemistry and Physics (85th ed.). Boca Raton, Florida: CRC Press. ISBN 978-0-8493-0485-9.

External links

• NLM Hazardous Substances Databank – Iridium, Radioactive (referring to iridium-192)

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Table of nuclides Categories: Isotopes Tables of nuclides Metastable isotopes Isotopes by element

• Isotopes of iridium
• Iridium
• Lists of isotopes by element