Dynamic Light Scattering from Nematic Liquid Crystals

Dynamic Light Scattering from Nematic Liquid Crystals... 

Benmouna, F. Peng, B. Gapinski, J. Patkowski. A. Ruhe. J. Johannsmann, D. Dynamic light scattering from liquid crystal polymer brushes swollen in a nematic solvent. Liq. Cry St. 2001, 2S, 1353- 1360. 

C. Deutsch and P. N. Keating, Scattering of Coherent Light from Nematic Liquid Crystals In the Dynamic Scattering Mode, J. Appl. Rhys., 40, p. 4049 (1969). 

Three of the experiments are completely new, and all make use of optical measurements. One involves a temperature study of the birefringence in a liquid crystal to determine the evolution of nematic order as one approaches the transition to an isotropic phase. The second uses dynamic laser light scattering from an aqueous dispersion of polystyrene spheres to determine the autocorrelation function that characterizes the size of these particles. The third is a study of the absorption and fluorescence spectra of CdSe nanocrystals (quantum dots) and involves modeling of these in terms of simple quantum mechanical concepts. 

The Orsay Liquid Crystal Group [28] determined a model of director modes of fluctuation based on the hydrodynamic description of nematic phases by Leslie [29] and Ericksen [30]. This approach developed the subject of dynamic light scattering in liquid crystals, and allows viscoelastic ratios to be deduced from light scattering data. For singly scattered light from a material, the time... 

Fig. 4.5 Measured autocorrelation function of dynamically scattered light by orientational fluctuations in nematic liquid crystal 5CB. The circles represent the measured data and the solid line the stretched exponential lit to the data with the relaxation time r = 7.86 0.05 s and stretching exponent s = 0.84 zb 0.03. Reprinted with permission from [8]. Copyright by the American Physical Society...

---