Temperature dependent Raman spectroscopy of a nematic liquid crystal compound 6CHBT

Abstract

In this study, we have chosen a room temperature nematic liquid crystal (NLC) compound namely, 6CHBT [(trans-4′-n-hexylcyclohexyl) isothiocyanatobenzene] having clearing temperature at 42.8 °C. This particular liquid crystal (LC) exhibits a broad nematic phase from 13 °C to 42.8 °C. Among all the available spectroscopy techniques, Raman spectroscopy is one of the most convenient techniques to understand the various phase transitions of a LC compound. In order to understand the phase change and the change of the molecular orientations along with their change in the chemical bond, the temperature dependent Raman study has been conducted for the LC compound 6CHBT. The transition temperatures of various phases obtained from the linewidth peak positions of Raman spectra agrees well with the literature data. From the Raman spectra, the change in chemical bonds is observed which is due to the increase in the molecular orientation of the alkyl chain in the LC compound. The bond assignment of the experimental value agrees well with the Raman assignment obtained from literature.