Semidecoupled Band and Shape Driving Effect of the π1/2^-541 Orbital in ¹⁷⁰Ta

High spin states in ¹⁷⁰Ta have been studied via ¹⁵⁹Tb(¹⁶O, 5nγ )¹⁷⁰Ta reaction at 105MeV beam energy. Three rotational bands have been observed among which one coupled band and an unfavored ΔI = 2 transition sequence of the semidecoupled band are identified in this work. The effects of the π1/2^-541 proton intruder orbital are qualitatively discussed.