Dynamics of a low temperature phase transition in liquid crystal TB10A probed by Raman spectroscopy

Raman spectra of TB10A were recorded in the regions, 925-1000 and 1140-1220cm-1 from room temperature down to 20 K, during cooling and heating cycles. The subtle changes in the spectral features of the bands at 975 and 1195cm-1 at 47 K were attributed to a hitherto unreported stable-metastable phase transition in TB10A. The dynamics of the new phase transition have been explained in terms of splitting of the non-planar mode at 975cm-1 owing to strong intermolecular interaction due to close molecular packing in the low temperature phase. The spectral anomaly of the 975cm-1 band, in terms of variation of relative intensity with respect to temperature, also shows the hysterisis linked with the process of stable-metastable-stable modification in TB10A.