The properties of the α${+}^{16}$O interaction in the vicinity of the Coulomb barrier are investigated by constructing (real, energy-independent) potentials which reproduce—when resonant nonpotential contributions are added to the potential background—all available ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$(α,α) elastic scattering angular distributions and excitation functions between 3.5 and 9 MeV incident energies. These low energy potentials, which are constructed for angular momenta ranging from 0 to 5, are in line with the global potential extracted from the analysis of the higher energy data (20≤${\mathit{E}}_{\mathrm{\alpha }}$≤150 MeV), but a slight angular momentum dependence, and an increase of the barrier height of about 1 MeV, are found necessary to reproduce the low energy data; this effect is qualitatively similar to that predicted by calculations taking into account antisymmetrization or dispersion relation effects. These potentials reproduce the properties of the first three members of the ${}_{}{}^{20}{}_{}{}^{}\mathrm{Ne}$ ${\mathit{K}}^{\mathrm{\pi }}$=$0_4^{+}$ ‘‘higher nodal’’ rotational band, which dominate the scattering in the investigated energy range, and of the ${\mathit{J}}^{\mathrm{\pi }}$=$5^{\mathrm{-}}$ member of the ${\mathit{K}}^{\mathrm{\pi }}$=$0^{\mathrm{-}}$ ‘‘inversion doublet’’ band. By taking into account the energy dependence of the interaction at lower energy, these potentials also give a nice account of the properties of the ${\mathit{J}}^{\mathrm{\pi }}$=$1^{\mathrm{-}}$ and $3^{\mathrm{-}}$ members of the same band, and are found to be compatible with the properties of the first three members of the ${}_{}{}^{20}{}_{}{}^{}\mathrm{Ne}$ ground state band.

• Received 2 February 1995

DOI:https://doi.org/10.1103/PhysRevC.51.3290