Dynamics of phase transitions in a liquid crystalline compound (TBDA) probed by Raman spectroscopy

Abstract

The precise value of linewidths obtained after correcting for the slitwidth effect for five Raman bands associated with the core of a liquid crystalline compound, terepthal-bis-decyl aniline (TBDA), have been studied in the temperature range of 12 - 472 K. The variation of the linewidth with temperature confirms two already reported phase transitions at 346 and 427 K. However, the phase transition at 427 K is not purely first order as reported earlier, but of mixed order in nature. From the measured linewidths of the and modes below room temperature, the estimated activation energy for rotation along the bond closely matches with the phase transition temperature suggesting that the rotation about the bond is closely linked with this transition.