The structure of the nucleus 96 39Y57 is discussed in the framework of the parabolic rule for the splitting of members of proton-neutron coupled configurations and of the interacting boson-fermion-fermion model (IBFFM). A good description of the available experimental data including the existence of the /~-decaying 8 + isomer with a half-life of 10 s has been obtained which demonstrates the influence of the subshell closures in the neighbourhood of 96Zr56.

An overview of the calculations in IBFM and IBFFM for nuclei in the A .. 100 region is presented. The application to these nuclei with a complex structure including the rapid transition from spherical to deformed nuclear shapes provides a stringent test for the capacities of this theoretical approach. From the result of the studies of the heavy Yttrium isotopes and the N=59 isotones it is concluded that it can account for the basic structure and the phase transition in these nuclei.

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An 8 + state has been identified at 4390 keY in the doubly semi-magic nucleus 96Zr through the study of angular correlations among the y radiation which is emitted in the B-decay of the 10 s isomer of 96y. This state probably has the configuration ~g~.~ and is populated through a GT decay from ~h~ 8~6member of the [~g^,^(~)vg~,~]

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