High-spin states in 126Cs were populated in the reaction 116Cd(14N, 4n)at a beam energy of 65 MeV. About 50 new transitions were placed in a level scheme that consists of six rotational structures, three of which have been observed for the first time. The newly observed bands and a previously reported but uninterpreted band were assigned configurations based on their population, aligned angular momentum, energy signature splitting and B(M1)/B(E2)ratios (for the strongly coupled bands).

The excitation energy systematics of ph11/2⊗n h11/2 yrast bands of odd-odd isotopes 118-132Cs are studied, and as a result of this study we suggest that the spin values of lowest observed states of yrast bands of 118,122,124,126,128Cs be reassigned as 8, 9, 9, 9, and 10, respectively. These new spin assignments are also supported by the argument of alignment additivity.

According to the argument of excitation energy systematics, new spin values are assigned to the lowest observed states of the ph11/2⊗n h11/2 bands for doubly odd nuclei 124,126,130,132,134La, 130-134Pr, 136,138Pm, and 138Eu, and possible new spin values are discussed for doubly odd nuclei 120-130Cs. Based on these new spin assignments, two systematic features of the ph11/2⊗n h11/2 bands are revealed. First, the low spin signature of the ph11/2⊗n h11/2 band is inverted for all doubly odd nuclei discussed in the present work. Second, the observed inversion spin increases with increasing neutron number for Cs and La isotopes. These features are in agreement with the recent systematic calculations based on the particle-triaxial-rotor model, with the inclusion of zero-range residual interaction between unpaired proton and neutron of Semmes and Ragnarsson, performed by Tajima.