Iridium: isotope data

Iridium has two isotopes, Ir-191 and Ir-193 and both are used in the production of radioactive material. Ir-191 is used for the production of radioactive Ir-192. This Ir-192 is used as a radiation source in gamma cameras that are used for non-destructive testing. Ir-192 sources are also used in so-called brachytherapy procedures whereby radioactive materials are placed in close contact with the tissue being treated. Although Ir-192 can be produced from natural Ir, the use of enriched Ir-191 gives a much higher specific activity and allows the use of smaller sources. The use of Ir-193 has been suggested for the production of the therapeutic radioisotope Pt-195m.

Naturally occurring isotopes

This table shows information about naturally occuring isotopes, their atomic masses, their natural abundances, their nuclear spins, and their magnetic moments. Further data for radioisotopes (radioactive isotopes) of iridium are listed (including any which occur naturally) below.
Isotope Mass / Da Natural abundance (atom %) Nuclear spin (I) Magnetic moment (μ/μN)
191Ir 190.960584 (4) 37.3 (2) 3/2 0.1462
193Ir 192.962917 (4) 62.7 (2) 3/2 0.1592

In the above, the most intense ion is set to 100% since this corresponds best to the output from a mass spectrometer. This is not to be confused with the relative percentage isotope abundances which totals 100% for all the naturally occurring isotopes.

Radiosotope data

Further data for naturally occuring isotopes of iridium are listed above. This table gives information about some radiosotopes of iridium, their masses, their half-lives, their modes of decay, their nuclear spins, and their nuclear magnetic moments.
Isotope Mass / Da Half-life Mode of decay Nuclear spin Nuclear magnetic moment
188Ir 187.95885 1.72 d EC to 188Os 2 0.30
189Ir 188.95872 13.2 d EC to 189Os 3/2 0.13
190Ir 189.9606 11.8 d EC to 190Os 4 0.04
192Ir 191.962602 73.83 d β- to 192Pt 4 1.92

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  1. Naturally occurring isotope abundances: Commission on Atomic Weights and Isotopic Abundances report for the International Union of Pure and Applied Chemistry in Isotopic Compositions of the Elements 1989, Pure and Applied Chemistry, 1998, 70, 217. [Copyright 1998 IUPAC]
  2. For further information about radioisotopes see Jonghwa Chang's (Korea Atomic Energy Research Institute) Table of the Nuclides
  3. Masses, nuclear spins, and magnetic moments: I. Mills, T. Cvitas, K. Homann, N. Kallay, and K. Kuchitsu in Quantities, Units and Symbols in Physical Chemistry, Blackwell Scientific Publications, Oxford, UK, 1988. [Copyright 1988 IUPAC]

NMR Properties of iridium

Common reference compound: no defined reference.

Table of NMR-active nucleus propeties of iridium
  Isotope 1 Isotope 2 Isotope 3
Isotope 191Ir 193Ir
Natural abundance /% 37.3 62.7
Spin (I) 3/2 3/2
Frequency relative to 1H = 100 (MHz) 1.719500 1.872500
Receptivity, DP, relative to 1H = 1.00 0.0000109 0.0000234
Receptivity, DC, relative to 13C = 1.00 0.0620 0.134
Magnetogyric ratio, γ (107 rad T‑1 s-1) 0.4812 0.5227
Magnetic moment, μ (μN) 0.1946 0.2113
Nuclear quadrupole moment, Q/millibarn +816(9) +751(9)
Line width factor, 1056 l (m4) 0.89 0.75


  1. R.K. Harris in Encyclopedia of Nuclear Magnetic Resonance, D.M. Granty and R.K. Harris, (eds.), vol. 5, John Wiley & Sons, Chichester, UK, 1996. I am grateful to Professor Robin Harris (University of Durham, UK) who provided much of the NMR data, which are copyright 1996 IUPAC, adapted from his contribution contained within this reference.
  2. J. Mason in Multinuclear NMR, Plenum Press, New York, USA, 1987. Where given, data for certain radioactive nuclei are from this reference.
  3. P. Pyykkö, Mol. Phys., 2008, 106, 1965-1974.
  4. P. Pyykkö, Mol. Phys., 2001, 99, 1617-1629.
  5. P. Pyykkö, Z. Naturforsch., 1992, 47a, 189. I am grateful to Professor Pekka Pyykkö (University of Helsinki, Finland) who provided the nuclear quadrupole moment data in this and the following two references.
  6. D.R. Lide, (ed.), CRC Handbook of Chemistry and Physics 1999-2000 : A Ready-Reference Book of Chemical and Physical Data (CRC Handbook of Chemistry and Physics, CRC Press, Boca Raton, Florida, USA, 79th edition, 1998.
  7. P. Pyykkö, personal communication, 1998, 204, 2008, 2010.

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