Fine structure of proton-neutron mixed symmetry states in some N = 80 isotones

The recently measured low‐energy spectra of the N = 80 isotones 134Xe, 136Ba and 138Ce have been investigated in the quasiparticle‐phonon model. The energies and transition strengths are well reproduced. While the observed selection rules reflect the neutron‐proton symmetry and phonon content of the excited states involved in the transitions, the splitting of the M1 strength in 138Ce is shown to be linked to a subtle interplay between pairing and single particle levels across the proton subshell closure.