Electrooptic Measurements

Electrooptic Measurements. The final characterization method to be discussed is the measurement of the electrooptic coefficient. The electrooptic effect is derived from... 

Chen, A., V. Chuyanov, S. Garner, W.H. Steier, and L.R. Dalton, 1997. Modified attenuated total reflection for the fast and routine electrooptic measurements of nonlinear optical polymer thin films. In Organic thin films for photonic applications, Vol. 14, OSA Technical Digest Series, 158-159. Washington, D.C. Optical Society of America [In 2001, the chromium coating on the prism of the use ATR setup was changed to ITO for measurements at 1.3 microns (where chromium is too lossy)]. 

Fig. 11.20 A typical set-up for electrooptic measurements of liquid crystal physical parameters...

In the Ising model, all the molecules are in the tilt plane but, despite such a severe simplification, the electrooptic measurements and resonant X-ray scattering [29] have confirmed the sequence of ferro- ferri- and antiferroelectric phases. However, the same X-ray experiments clearly showed that the tilt planes in different layers are not at all parallel. Moreover, in frameworks of the Ising models the structure of the SmC o, phase could not be understood. Therefore, another approach has been developed. 

The authors wish to thank Robert Burmeister and Robert Archer for their continued support of this work and George LaBelle for performing the electrooptical measurements. 

Today the electrooptical properties of liquid crystals form well-developed branches both in the physics and technology of liquid crystals. In addition, electrooptical measurements are the basis of a number of precise methods for determining the physical parameters of a material, such as its elastic and viscosity coefficients, optical anisotropy, spontaneous polarization, flexoelectric coefficients, anchoring energies at interfaces, etc. 

D. Pbrschke, K. Tovar, and J. Antosiewicz, Biochemistry, TTl, 4674 (1988). Structure of Tet Repressor and Tet Repressor-Operator Complexes in Solution from Electrooptical Measurements and Hydrodynamic Simulations. 

D. Pbrschke, Biophys. Chem., 40,169 (1991). Persistence Length and Bending Dynamics of DNA from Electrooptical Measurements at High Salt Concentrations. 

Electrooptical Measurements Demonstrate a Large Permanent Dipole Moment Associated with Acetylcholinesterase. 

Figure 69. (a) The experimental setup for electrooptic measurements. The sample is placed between crossed polarizers, (b) The RC-cir-cuit used in the switching experiments. The current response from the sample is measured across the resistor R (from Hermann [136]). 

A last point should not be forget in the comparison of dielectric and electrooptic measurements of the polarisability. The latter one measures in fact the anisotropy of polarisability (Xy — We have considered our result as giving ay and compared it to theories which neglect any transversal displacement of the counter-ions. While this is reasonable it doesn t means that transversal movements or end effects do not play a role in the value of the dielectric constant and its dispersion. 

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