Isomer of 130I

The existence of the isomer 130Im (9.2 min) has been established by the growth of the gamma‐ray spectrum of the 130I ground state following neutron irradiation of 129I, and also by the incorporation of 130I into organic combination as a result of the isomeric transition of I2(130Im) dissolved in n‐hexane. The isomer decays to the ground state by a highly converted isomeric transition with a 0.77 probability and to the 0.54‐MeV level of 130Xe by beta emission with 0.23 probability. The cross‐section ratio, σ(130Im)/σ(130I), for production of the isomers from 129I by pile neutrons is about 2.0. The fraction of the isomeric transition events which result in organic incorporation of the 130I daughter in solutions of I2(130Im) in n‐hexane, or in solutions of RI(130Im) in ethyl iodide, is about 0.40.