The $\gamma$-ray energies and intensities in the decay of iridium-189 have been measured with Ge(Li) and Si(Li) detectors, and the internal-conversion coefficients of 15 lines have been estimated. The mean life of the 276-keV state was found to be less than 0.4 nsec by electronic means. Limits were established for the mean life of the 95.3-keV state by the Mössbauer effect (greater than 0.2 nsec) and by electronic means (less than 0.4 nsec). The mean life of the 69.6-keV level was found to be 2.35±0.06 nsec, and a single line of corresponding width was observed in the Mössbauer effect. The nuclear Zeeman effect gave the magnetic moment of the 69.6-keV state as 0.965±0.020 ${\mathrm{\mu }}_{\mathit{N}}$ with $\frac{E2\mathrm{}}{M1\mathrm{}}=0.57\mathrm{}\pm 0.21$ and an internal magnetic field of 1.085±0.052 MG acting on the osmium nucleus in a dilute iron alloy. The electromagnetic properties of the 69.6-keV level are completely consistent with its pure rotational character.

• Received 21 October 1968

DOI:https://doi.org/10.1103/PhysRev.180.1158