Abstract
The very neutron deficient Z = N + 1 nuelei 7739Y, 7940Zr, and 8342Mo have been observed for the first time following the fragmentation of a 92Mo beam. In contrast, no evidence was found for the existence of 8141Nb and 8543Tc. The observation of 7739Y is of particular interest in light of the instability of the odd-proton, Z = N + 1 systems, 6935Br, 7337Rb, 8141Nb, and 8543Tc, and may be explained as a consequence of the shape polarizing effect of the highly deformed, prolate Z = N = 38 core. The experimental results are discussed within the framework of the shell-correction model, which together with proton-decay calculations allow an estimate of the proton separation energies of these highly exotic systems to be calculated.