Vibrational Spectroscopy of Liquid Crystals: IV. Infrared and Far Infrared Spectra of the MBBA and EBBA Liquid Crystals

Infrared spectra have been recorded for N(p-methoxy) benzylidene- (p-n-butyl) aniline (MBBA) and its ethoxy analog in the crystalline, mesomorphic and isotropic phases. From the spectra obtained for a homeotropic layer in the nematic phase and for an isotropic layer, assignments of the bands are given which are supported by a previous normal coordinate analysis for benzylidene-aniline. Far infrared spectra have also been investigated for these compounds. The observed bands mostly consist of internal vibrations except the presence of a 120 cm −1 band assigned to a librational mode about the long axis of the molecule.