RUI: Forced Rayleigh scattering on heterogeneous liquid crystals: Directional solidification at forced wavevectors

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Dr. Daniel R. Spiegel of Trinity University is funded for his research on forced Rayleigh scattering (FRS) on heterogeneous liquid crystals by the Physical Chemistry Program of the Chemistry Division. The interfacial modulation accompanying an impurity-diffusion-driven instability during nematic-directional solidification can be stimulated and probed by FRS techniques. Non-homogeneous perturbations at selected wavelengths (frequencies) of such transforming systems will be used to experimentally probe the nonlinear reaction-diffusion modeling and pattern formation of such liquid-crystal systems. FRS pump-beam interference fringes will be used to effect modulation of the nematic-isotropic interface of a directionally solidified liquid crystal. The temporal evolution of specific Fourier component amplitudes will be tracked using diffracted FRS probe beams. Fundamentally important dispersion relations relevant to the basic linear instability will be mapped experimentally.Nonlinear dynamical systems, including those that produce non-equilibrium pattern formation, are becoming increasingly upbiquitous in research and in chemcial industry. The analysis and modeling of such systems is important for developing quantitative methods for controlling such phenomena. The FRS experiments at Trinity University should provide definite means for improving our experimental approaches to developing such models, and for testing our understanding of such models. Furthermore, invaluable state-of-the-art training will be afforded the undergraduates participating in this research program.