The feeding and decay patterns of isomers in odd-odd iodine nuclei, produced in heavy-ion fusion-evaporation reactions and separated by a recoil mass spectrometer, have been studied with the γ-ray spectroscopy technique. A new isomer in ${}_{}{}^{116}{}_{}{}^{}\mathrm{I}$, fed by a known collective band, was identified and its half-life was measured to be 3.27±0.16 μs. An isomer was confirmed to exist in ${}_{}{}^{122}{}_{}{}^{}\mathrm{I}$ with a measured half-life of 80±8 μs in agreement with two previous determinations. It is established from our study that these isomers serve as links between the high-spin and low-spin states in ${}_{}{}^{116,122}{}_{}{}^{}\mathrm{I}$. The characteristic properties of low excitation energy and high spin of these isomers are evident. As a by-product in the study of ${}_{}{}^{122}{}_{}{}^{}\mathrm{I}$, the half-life of a known high-spin isomer in ${}_{}{}^{121}{}_{}{}^{}\mathrm{I}$ was measured to be 16.0±1.4 μs, which disagrees with an early measurement of 9.0±1.5 μs. Its isomeric transition has an energy of 135 keV as suggested by our data in contrast to the value of 159 keV reported earlier.

• Received 20 October 1989

DOI:https://doi.org/10.1103/PhysRevC.41.1600