Toroidal quadrupole transitions associated to collective rotational-vibrational motions of the nucleus

. In the frame of the collective model one computes the longitudinal, transverse and toroidal multipoles corresponding to the excitations of low-lying levels in the ground state band of several even-even nuclei by inelastic electron scattering ( e, e ′ ). In connection with this transitions a new quantity, which accounts for the deviations from the Siegert theorem, is introduced in the frame of the Riemann Rotational Model with non-vanishing vorticity. Inelastic differential cross-sections calculated at backscattering angles shows the dominancy of toroidal form-factors over a broad range of momentum transfer