Quadrupole moment of 19/2^- isomeric state in ¹³⁷La and 21/2^- isomeric state in ¹³¹La

The nuclei in the A ∼ 130 mass region are known to be soft with respect to the triaxial deformation, and thus are sensitive to the polarizing effect of specific quasiparticle configuration. This can lead to the coexistence of quadrupole structures which can be determined by the configuration of the valence quasiparticles. In this mass region, both protons and neutrons can occupy the unique-parity h_11/2 intruder orbitals which play an important role in driving the nuclear shape. The different deformation driving properties of neutrons and protons lead to either a prolate, oblate or triaxial shape depending on the configuration