Molecular and Intramolecular Motions in Dual-Frequency Nematic Liquid Crystal, at Extra Low Temperatures, Observed by Means of Dielectric Spectroscopy

Abstract

New dual frequency nematic liquid crystal mixture has been prepared and investigated by means of dielectric spectroscopy in a wide temperature range (from 120°C to −100°C). The molecular structures of compounds used to prepare the final mixture and mixture's composition influence its dielectric properties. Wide temperature investigations show how molecular and intramolecular motions change with temperature. It is possible at low temperatures to slow down intramolecular motions so much that they are visible in dielectric spectroscopy. At −80°C molecular motions disappear from dielectric response. At −100°C all thermally activated motions are too slow to be detected by means of dielectric spectroscopy.

Keywords:

• dual frequency nematic
• relaxation frequency
• Havriliak-Negami model
• molecular modes
• S-mode
• L-mode
• intramolecular modes