  We have performed a heavy ion radiative capture reaction between two light
heavy ions, $^{12}$C and $^{16}$O, leading to $^{28}$Si. The present experiment
has been performed below Coulomb barrier energies in order to reduce the phase
space and to try to shed light on structural effects. Obtained $\gamma$-spectra
display a previously unobserved strong feeding of intermediate states around 11
MeV at these energies. This new decay branch is not fully reproduced by
statistical nor semi-statistical decay scenarii and may imply structural
effects. Radiative capture cross-sections are extracted from the data.
