The α-cluster structure of the ${}_{}{}^{18}{}_{}{}^{}\mathrm{O}$ nucleus is investigated by studying the properties of a global optical model potential which describes ${}_{}{}^{14}{}_{}{}^{}\mathrm{C}$(α,α) elastic scattering at 28, 40, and 54 MeV on the whole angular range. This calculation does not support the existence of the negative-parity molecular dipole states which have been proposed to coexist with the positive-parity four-particle–two-hole (4p-2h) deformed band built on the ${\mathit{J}}^{\mathrm{\pi }}$=$0^{+}$, ${\mathit{E}}_{\mathit{x}}$=3.63 MeV state. It suggests that the broad ${\mathit{J}}^{\mathrm{\pi }}$=$1^{\mathrm{-}}$ state recently seen around ${\mathit{E}}_{\mathit{x}}$=9 MeV in the β-delayed α-particle spectrum from ${}_{}{}^{18}{}_{}{}^{}\mathrm{N}$ is the bandhead of the negative-parity inversion-doublet partner band of the 4p-2h band.

• Received 28 January 1993

DOI:https://doi.org/10.1103/PhysRevC.47.R1846