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

Abstract

Raman spectra of TB10A were recorded in the regions, 925± 1000 and 1140± 1220 cm Õ 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~1195 cm Õ 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 975 cm Õ 1 owing to strong intermolecular interaction due to close molecular packing in the low temperature phase. The spectral anomaly of the 975 cm Õ 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 modi® cation in TB10A.