Interplay between single-particle and collective degrees of freedom in the excitation of the low-lying states in ${}_{}{}^{140}{}_{}{}^{}\mathrm{Ce}$

Differential cross sections for electron scattering from ${}_{}{}^{140}{}_{}{}^{}\mathrm{Ce}$ have been measured for excitation energies less than 3.3 MeV over a range of effective momentum transfer of 0.4 to 3.1 ${\mathrm{fm}}^{\mathrm{-}1}$. The data have been analyzed to extract transition charge densities. These densities are interpreted in terms of a quasiparticle-phonon model and self-consistent finite Fermi system theory to disentangle the collective and noncollective modes of excitation.