Interprétation des Profils d'Excitation Obtenus par Raman de Résonance des Modes de Vibration de la Diéthylcyanine

The excitation profiles of several vibrational Raman bands of diethylcyanine are examined where the exictation is applied to the first electronic transition. In order to analyse these profiles, firstly, a study of the electronic spectrum is carried out: the symmetry of the first electronic state is determined from an experimental approach (polarization of vibrational and electronic spectra) and from a theoretical approach (Hartree‐Fock semiempirical calculations); secondly, the vibration excitation profile located at 1368 cm −1 is analysed. The parameters of this vibration (1368 cm −1 ) and the mechanism of the scattering are obtained with the help of Raman and absorption spectra. A comparison between the scattered intensity and the 1368 cm −1 vibration intensity allows the studies of excitation profiles of the other vibrations.