High-spin level scheme of doubly odd 128I

High-spin states in the odd-odd I-128 have been studied experimentally using the Sn-124(Li-7, 3n gamma) I-128 reaction at beam energies of 28 and 32 MeV. A level scheme built on the known T-1/2 = 175 ns, (6(-)) isomer has been established. The low-lying states in the level scheme have been proposed to be associated with the pi d(5/2) circle times nu h(11/2) and pi g(7/2) circle times nu h(11/2) two-quasiparticle excitations. The strongly populated negative-parity states, forming a bandlike structure, have been assigned to be based on the pi g(7/2) circle times nu h(11/2) configuration. The pi h(11/2) circle times nu h(11/2) multiplet 9(+), 10(+), and 11(+) members have been identified according to the systematics of the corresponding level structures observed in the lighter odd-odd iodine isotopes. The two-quasiparticle configuration assignments are supported by the nucleon pair approximation and empirical shell-model calculations.