Intruder πh _{9 2} and πi _{13 2} bands in Re and Ir nuclei

Experimental aligned angular momenta, band-crossing frequencies, and relative transition rates are systematically analyzed for a series of Re and Ir isotopes. Configuration-dependent nuclear shapes associated with the occupation of the πi _{13 2}, πh _{9 2}, πh _{11 2}, and πd _{5 2} configurations are especially emphasized in the discussion. It is found that the πi _{13 2} orbit has a strong, positive-β₂ driving effect on the nuclear shape, while the driving force of the πh _{9 2} orbit is minimized when the Fermi level is close to this orbit. The gradual alignment gains observed in bands built on the πh _{11 2} and πd _{5 2} configurations could be associated with νi _{13 2} crossings brought low in rotational frequency by smaller β₂ and/or more negative γ values.