Isomeric states of fission fragments explored via Penning trap mass spectrometry at IGISOL

The masses of ⁸⁴Br, ¹⁰⁵Mo, 115,119,121Pd, ¹²²Ag, 127,129In, ¹³²Sb and their respective isomeric states have been measured with the JYFLTRAP Penning trap mass spectrometer using the phase-imaging ion-cyclotron-resonance technique. The excitation energies of the isomeric states in ¹³²Sb and ¹¹⁹Pd were experimentally determined for the first time, while for ⁸⁴Br, ¹¹⁵Pd and 127,129In, the precision of the mass values was substantially improved. In ¹⁰⁵Mo and ¹²¹Pd there were no signs of a long-lived isomeric state. The ground-state measurements of ¹¹⁹Pd and ¹²²Ag indicated that both are significantly more bound than the literature values. For ¹²²Ag, there was no indication of a proposed third long-lived state. The results for the $N=49$ nucleus ⁸⁴Br and isomers close to doubly magic ¹³²Sn have been compared to the shell-model and the microscopic quasiparticle-phonon model calculations.