On the investigation of field-induced director dynamics: a novel ESR experiment

Becker, J., Dunmur, D.A., Dunn, C.J., Luckhurst, G.R., Marchant-Lane, S.E. and Timimi, B.A. (2003) On the investigation of field-induced director dynamics: a novel ESR experiment. Molecular Crystals and Liquid Crystals, 394 (1), 45-61.

Abstract

The rotational viscosity coefficient of a nematic liquid crystal with a positive diamagnetic susceptibility anisotropy can be determined by monitoring the time dependence of the director orientation as it is rotated by a field from a non-equilibrium to the equilibrium state parallel to the field. A variety of techniques is available using different properties to monitor the director orientation as a function of time. Normally these experiments are designed so that the property used to determine the director orientation does not change during the time taken for its measurement. Here using ESR spectroscopy, we explore the benefits of exploiting exactly the opposite situation. That is during the time taken to record the ESR spectrum the director orientation is allowed to change. We have developed both semi-quantitative and quantitative models to allow us to simulate how the form of the spectrum depends on experimental conditions such as the field scan rate. These models have also proved to be valuable in designing the experiment and in analysing the spectra. It seems that this novel ESR experiment provides a valuable route to the field-induced relaxation time and hence to the rotational viscosity coefficient.

This record has no associated files available for download.

Contributors

Download statistics