We report on the first low-energy Coulomb excitation measurements with radioactive I 6 ÿ beams of odd-odd nuclei 68;70 Cu. The beams were produced at ISOLDE, CERN and were post-accelerated by REX-ISOLDE to 2:83 MeV=nucleon. rays were detected with the MINIBALL spectrometer. The 6 ÿ beam was used to study the multiplet of states (3 ÿ , 4 ÿ , 5 ÿ , 6 ÿ ) arising from the 2p 3=2 1g 9=2 configuration. The 4 ÿ state of the multiplet was populated via Coulomb excitation and the BE2; 6 ÿ ! 4 ÿ value was determined in both nuclei. The results obtained illustrate the fragile stability of the Z 28 shell and N 40 subshell closures. A comparison with large-scale shell-model calculations using the 56 Ni core shows the importance of the proton excitations across the Z 28 shell gap to the understanding of the nuclear structure in the neutron-rich nuclei with N 40. Radioactive beams provide great opportunities for investigating the nuclear structure away from the stable nuclei. One of the regions of the nuclear chart that has attracted a considerable interest in the past years is the one close to 68 Ni [1][2][3][4][5][6][7][8]. Coulomb excitation experiments with radioactive beams of even-even isotopes showed that the coupling of a few extra particles to the 68 Ni core induces large polarization effects [2,3]. These effects were associated with a weakening of the Z 28 and N 40 gaps when neutrons start filling the 1g 9=2 orbital [2]. Beyond N 40, results of -decay measurements in the neutronrich [69][70][71][72][73] Cu isotopes revealed a dramatic and sudden lowering of the 1f 5=2 orbital with the increased occupancy of the 1g 9=2 orbital [4]. Referred to as monopole migration, this energy shift was interpreted as originating from the residual proton-neutron interaction and it is expected to have profound implications on the structure of the doubly magic nucleus 78 Ni [4,5].Shell-model calculations using different effective nucleon-nucleon interactions were used in order to understand the observed properties in the nuclei around 68 Ni and predict the evolution of the shell structure towards 78 Ni [5][6][7][8]. The calculations indicated that the values of the Z 28 and N 40, 50 energy gaps strongly depend on the effective interaction used. A consistent understanding of the evolution of the nuclear structure in these regions requires also experimental information such as excitation energies and transition rates in the odd-A and odd-odd nuclei.