Vibrational Spectra of Liquid Crystals. II. The Raman Spectrum of p-Azoxyanisole in Crystal, Nematic, and Isotropic Phases, 10–100-cm−1 Region

The Raman spectrum of p-azoxyanisole has been observed in the crystal, nematic, and isotropic phases between 10 and 100 cm−1. The spectrum of an oriented single crystal at − 90°C shows that all 12 predicted lattice modes are found. In the polycrystalline sample, a soft mode is observed as the crystal–nematic transition is approached. The liquid crystal exhibits pseudolattice modes, which disappear in the isotropic melt. Assignments for the observed bands are discussed.