Form-factor measurements in the momentum-transfer range 0.6≤q≤2.7 ${\mathrm{fm}}^{\mathrm{-}1}$ are presented for the $1^{\mathrm{-}}$ levels in ${}_{}{}^{18}{}_{}{}^{}\mathrm{O}$ at 4.46, 6.20, 7.62, and 8.04 MeV, the $3^{\mathrm{-}}$ levels at 5.10, 6.40, and 8.29 MeV, and the $5^{\mathrm{-}}$ levels at 7.86 and 8.13 MeV. These are the first measurements of the $5^{\mathrm{-}}$ states by inelastic scattering and the first electron-scattering measurements of the higher $1^{\mathrm{-}}$ and $3^{\mathrm{-}}$ states. A Rosenbluth separation of the longitudinal and transverse form factors was performed by fitting the data with a phenomenological polynomial-times-Gaussian parametrization motivated by the form of theoretical form factors when harmonic-oscillator wave functions are used. Comparisons are made with structure models. The Coulomb form factors of several levels indicate the significance of small admixtures of 3ħω components in the negative-parity wave functions.

• Received 1 November 1990

DOI:https://doi.org/10.1103/PhysRevC.43.2147