Measurements of γ-ray singles and γγ-coincidence spectra, γ-ray angular distributions, and Doppler shift attenuation have been made, following the reaction ${}_{}{}^{63}{}_{}{}^{}\mathrm{Cu}$${(}^4$He,pn${)}^{65}$Zn at 30 MeV. The level scheme has been confirmed up to 5773 keV. The spins and parities of the three states at 3227.6, 3785.7, and 4938.0 keV, hitherto uncertain or unknown, are found to be 17/$2^{+}$, 17/$2^{+}$, and 21/$2^{+}$, respectively. The mean lives for these states, for which there is no information available in the literature, have been estimated, and the deduced B(E2) values for the 4938.0→3227.6 (21/$2^{+}$→17/$2^{+}$), 3227.6→2053.5 (17/$2^{+}$→13/$2^{+}$), and 3785.7→2053.5 (17/$2^{+}$→13/$2^{+}$)-keV transitions are all found to be strongly enhanced with respect to the Weisskopf single-particle estimates indicating collectivity in the structure of the concerned states. Evidence is presented in favor of the interpretation of the positive parity states in ${}_{}{}^{65}{}_{}{}^{}\mathrm{Zn}$ with ${\mathit{J}}^{\mathrm{\pi }}$ values 9/$2^{+}$ to 21/$2^{+}$, as arising from the weak coupling of a ${\mathit{g}}_{9/2}$ neutron to the quadrupole excitations of the ${}_{}{}^{64}{}_{}{}^{}\mathrm{Zn}$ core.

• Received 25 April 1994

DOI:https://doi.org/10.1103/PhysRevC.50.1813