Identification of excited structures in proton unbound nuclei 173,175,177Au:: shape co-existence and intruder bands

Excited states in the proton-unbound Au-173,Au-175,Au-177 nuclei were identified for the first time. Level structures associated with three different shapes were observed in Au-175. While the yrast lines of Au-175 and Au-177 consist of a prolate band built upon the intruder 1/2(+) [660] (i(13/2)) proton orbital, no sign of collectivity was observed in the lighter Au-173 isotope, Implications for the deformation associated with these structures are discussed with a focus on shape co-existence in the vicinity of the proton-drip line. (C) 2001 Published by Elsevier Science B.V.