Four $M4\mathrm{}$ transitions based on the stretched particle-hole excitation ${\left(1\mathrm{}{d}_{\frac{5}{2}}1p_{\frac{3}{2}}^{-1\mathrm{}}\right)}_{4^{-}}$ have been observed in ${}_{}{}^{14}{}_{}{}^{}\mathrm{N}$ by inelastic electron scattering, and their form factors have been measured over the range $q=0.8-2.8\mathrm{}$ ${\mathrm{fm}}^{-1\mathrm{}}$. The states are at 15.01 ($3^{-}$,$4^{-}$), 16.91 ($5^{-}$), 18.48 ($5^{-}$), and 20.11 MeV ($3^{-}$,$4^{-}$) and all have $T\approx 1$. The 16.91 and 18.48 MeV states together exhaust 61-84% of the possible $M4\mathrm{}$ strength for $J^{\pi }=5^{-}$, the higher percentage obtaining for a phenomenological ground-state wave function which fits the static electromagnetic moments. The 15.01 and 20.11 MeV transitions exhaust over 60% of the $M4\mathrm{}$ strength allowed for $J^{\pi }=3^{-}$, but the spins are still uncertain. Combined with recent ${}_{}{}^{14}{}_{}{}^{}\mathrm{N}(\pi ,{\pi }^{\prime })$ results, a triplet of $5^{-}$ states with $T=0,1,0\mathrm{}$ is apparent at 14.66, 16.91, and 17.46 MeV and a three-state isospin-mixing scheme is invoked to describe the $\frac{{\pi }^{+}}{{\pi }^{-}}$ asymmetries. Using the (e,e′) data as a calibration, and assuming a simplified ground-state wave function, the joint analysis indicates the $5^{-}$ triplet exhausts roughly 60% of the isovector $5^{-}$ strength but only about 35% of the isoscalar strength. Significant $C3\mathrm{}$ strength is found in a triplet of levels at 12.82 ($4^{-}$), 11.24 ($3^{-}$), and 13.17 MeV ($2^{-}$?). The form factors are interpreted in terms of a weak coupling of the valence nucleons to a $K=3\mathrm{}$ rotational excitation of a deformed core. Finally, an isovector $M2\mathrm{}$ transition is found at 14.72 MeV ($2^{-}$?) and is analyzed in terms of a phenomenological shell-model configuration.

• Received 27 June 1983

DOI:https://doi.org/10.1103/PhysRevC.29.1168