Raman spectroscopy is an important tool to understand the structural and molecular behaviour of the liquid crystals when they undergo through different temperatures. It also helps to understand the different phase changes of the liquid crystal material as temperature changes. In this work, the structural properties of two nematic liquid crystals having relatively high clearing temperature namely 4 butylcyclohexyl-3, 5-difluoro-4- isothiocyanato biphenyl and 4-pentylcyclohexyl-3, 5-difluoro-4-isothiocyanato biphenyl are studied. The study is done using temperature dependent Raman spectroscopy. From the studies of the two compounds it has been found that the experimental values are agree well with the various functional groups and different bond assignments recorded in literature. This agreement validates the presence of different functional groups and different stretching bonds in the two studied liquid crystal compounds. Deformations of some of the peak positions of the two liquid crystal compounds have been observed with the change in phase at different temperature. Also to understand the behaviour of the Raman peak near the clearing temperatures of the liquid crystal compounds the linewidth of the different peak values at different temperature have also been studied. From the line width study, the various phase transition temperatures of the two liquid crystalline compounds can be confirmed.

Department of Physics NIT Agartala Tripura 799046 India

Institute of Organic Chemistry and Biochemistry Czech Academy of Sciences Flemingovo náměstí 2 16610 Prague 6 Czech Republic

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