Comments on the Relaxation Process in the Cholesteric-Nematic Transition
The relaxation process by which a field-aligned nematic state returns to a helicoidal structure has been the subject of several studies. In this paper, we report some new transient optical and capacitive measurements which emphasize the dependence of the relaxation on sample boundary conditions. Homeotropic samples exhibit a delay time after field removal, followed by nucleation of the decay sequence about isolated points. During the decay, the capacitance decreases monotonically, but the light-scattering transient is structured even in the absence of polarizing optics. A spiral domain structure is observed for these samples. For samples with parallel boundary conditions, the transient capacitance data exhibit a minimum which supports earlier inferences of a tilted-Grandjean-planar structure.
KeywordsRelaxation Process Effective Dielectric Constant Director Distribution Capacitive Measurement Domain Texture
Unable to display preview. Download preview PDF.
- 5.The dynamics of the transition in samples with one free boundary have been studied by J. Prost and H. Gasporoux, Mol. Cryst. Liq. Cryst., to be published.Google Scholar
- 6.J.J. Wysocki, J. Adams, and D.J. Olechna, “Liquid Crystals and Ordered Fluids,” ed. J.F. Johnson and R.S. Porter, (Plenum Press, Inc., New York, 1970), p. 419.Google Scholar
- 9.R.A. Kashnow and H.S. Cole, Fourth International Liquid Crystal Conference, Kent, Ohio, 1972; Mol. Cryst. Liq. Cryst., to be published.Google Scholar
- 13.C.J. Gerritsma and P. Van Zanten, Phys. Lett. 37A, 47 (1971).Google Scholar
- 18.E. Jakeman and E.P. Raynes, Phys. Lett. 39A, 69 (1972) report very short decay times which may characterize the slope of the initial change in light transmission.Google Scholar
- 21.M. Klernan and J. Friedel, J. de Phys. 30C, 4 (1969).Google Scholar