Raman Study of Para-Azoxydianisole at the Phase Transitions

Raman scattering was used to probe the phase transitions of the nematic liquid-crystalline material, $p$-azoxydianisole. The intensities of several Raman modes were shown to change abruptly at the phase transitions, but no detectable frequency shift of any mode was observed. Our results suggest that the Raman spectrum of $p$-axoxydianisole is only affected by short-range ordering. Qualitative interpretation of the results is given.