Nuclear structure in the vicinity of shell closures far from stability

The status of experimental approach to 100Sn and 78Ni is reviewed. Revised single particle energies for neutrons are deduced for the N=Z=50 shell closure and evidence for low lying Iπ=2+ and 3- states is presented. Moderate E2 polarization charges of 0.1 e and 0.6 e are found to reproduce the experimental data when core excitation of 100Sn is properly accounted for in the shell model. For the neutron rich Ni region no conclusive evidence for an N=40 subshell is found, whereas firm evidence for the persistence of the N=50 shell at 78Ni is inferred from the existence of seniority isomers. The disappearance of this isomerism in the mid νg9/2 shell is discussed. The spectroscopy of 216Th disproves the existence of a Z=92 shell gap as predicted by some recent mean field calculations. Inversion of the πh9/2 and f7/2 orbitals at Z=90 is ascribed to the coupling of the f7/2 (and i13/2) protons to the low-lying 3- state (ℎω3=1.69 MeV). (orig.)