Some anomalies in the regularities of the SER spectra of benzene and hexafluorobenzene

The paper is devoted to qualitative explanation of some anomalies in the SER spectra of benzene adsorbed on lithium and hexafluorobenzene absorbed on silver in the framework of the dipole-quadrupole SERS theory. These anomalies manifest in the most enhancement of the bands which do not belong to the breathing vibrations of symmetrical molecules. We consider, that these anomalies are associated with large influence of the totality of coefficients which characterize excitation of excited states of the molecule by separate vibrations. On the base of this assumption a conclusion is made about possible lower influence of electromagnetic factor and specific influence of electron structure of molecules in the considered systems.