Radiations fromIr192m

The photon and electron spectra of ${\mathrm{Ir}}^{192m}$ (1.42 min) have been thoroughly investigated. Study of the photon spectrum with scintillation spectrometers and an aluminum-lined proportional counter spectrometer revealed the presence of a quantum continuum, iridium $L$ x-rays, and a 58-kev gamma ray. The quantum continuum was shown to be bremsstrahlung engendered by conversion electrons from the isomeric transition. Previous to this study, the quantum continuum had been interpreted as possibly caused by "two-quantum" emission. A high-resolution, 180° permanent magnet spectrograph was employed for the examination of the conversion electron spectrum. The energy of the isomeric transition was found to be 58.0±0.4 kev from the conversion electron studies. Lifetime-energy considerations and the observed $L$-subshell conversion ratios show that the 58.0-kev gamma ray is $E3\mathrm{}$. The $L$-shell conversion coefficient was determined from scintillation spectrometer data to be ≥ 870.