Interplay between Single-Particle and Collective Effects in the Odd-<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>A</mml:mi></mml:math>Cu Isotopes beyond<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>N</mml:mi><mml:mo>=</mml:mo><mml:mn>40</mml:mn></mml:math>

Collective properties of the low-lying levels in the odd-$A$ $^{67--73}\mathrm{Cu}$ were investigated by Coulomb excitation with radioactive beams. The beams were produced at ISOLDE and postaccelerated by REX-ISOLDE up to $2.99\text{ }\text{ }\mathrm{MeV}/\mathrm{u}$. In $^{67,69}\mathrm{Cu}$, low-lying $1/{2}^{\ensuremath{-}}$, $5/{2}^{\ensuremath{-}}$, and $7/{2}^{\ensuremath{-}}$ states were populated. In $^{71,73}\mathrm{Cu}$, besides the known transitions deexciting the single-particle-like $5/{2}^{\ensuremath{-}}$ and core-coupled $7/{2}^{\ensuremath{-}}$ levels, $\ensuremath{\gamma}$ rays of 454 and 135 keV, respectively, were observed for the first time. Based on a reanalysis of $\ensuremath{\beta}$-decay work and comparison with the systematics, a spin $1/{2}^{\ensuremath{-}}$ is suggested for these excited states. Three $B(E2)$ values were determined in each of the four isotopes. The results indicate a significant change in the structure of the odd-$A$ Cu isotopes beyond $N=40$ where single-particle-like and collective levels are suggested to coexist at very low excitation energies.

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