Partial conservation of seniority and its unexpected influence on E2 transitions in g9/2 nuclei

There exist two uniquely defined v=4 states in systems within a j=9/2 subshell, which automatically conserve seniority and do not mix with other states. Here I show that the partial conservation of seniority plays an essential role in our understanding of the electric quadrupole transitions of the semimagic nuclei involving j=9/2 subshells, including the long-lived 8+ isomer in 94Ru. The effects of configuration mixing from neighboring subshells on the structure of those unique states are analyzed. It is shown that a sharp transition from pure seniority coupling to a significant mixture between the v=2 and v=4 states may be induced by the cross-orbital non-diagonal interaction matrix elements. Such strong mixture is essential to explain the observed E2 transition properties of N=50 isotones 96Pd and 94Ru.