First observation of excited states in

The technique of recoil-decay tagging has been employed in order to observe excited yrast states in the neutron-deficient nucleus , for the first time. Interleaved bands of positive- and negative-parity states suggest the octupole nature of this nucleus, and the behaviour of the difference in aligned angular momentum between the negative- and positive-parity states with rotational frequency is consistent with that expected of a rotating reflection-asymmetric shape. This represents an extension of the known octupole-deformed nuclei to Z = 92. The interleaved bands of alternating parity are connected by strong electric dipole transitions, and values of , extracted from -ray branching ratios, suggest that possesses one of the largest E1 moments near to the ground state of the nuclei in this region.