AN FT-IR STUDY OF PECULIARITIES IN THE POLARIZED VIBRATIONAL-SPECTRA OF SOME AROMATIC NITRO-COMPOUNDS

FT-IR polarization spectra of oriented nematic solutions of nitrobenzene showed an anomaly consisting in the equal polarization of both symmetric and antisymmetric stretching bands of the nitro group. In order to clarify the observed phenomenon the polarization spectra of the nematic solutions of a series of p-substituted aromatic nitro compounds was studied. The contribution of the ring pi-electrons to the vibrational transition moment of the antisymmetric -NO2 stretching vibration seems to explain this anomaly.