Electrically light scattering from

Light scattering from macromolecules is used routinely to obtain molecular weights, radii of gyration and polymer-solvent and polymer-polymer interaction parameters. A closely related technique, electric field induced light scattering (EFLS) (13,14) has received less attention, but is also potentially useful for polymer characterization. 

Provided that fluid motion is uniform in the illuminated region of the suspension, then similar information may also be extracted by analysis of laser light scattering from particles undergoing electrophoretic motion, that is migratory motion in an electric field, superimposed on that motion. 

Phenomenon consequent upon the electric vectors of the incident and scattered beams being non-coplanar, such that light scattered from a vertically (horizontally) polarized incident beam contains a horizontal (vertical) component. 

The intensity I of the light scattered from a dilute macromolecular or supra-molecular solution is a fluctuating quantity due to the Brownian motion of the scattering particles. These fluctuations can be analysed in terms of the normalised autocorrelation function y1 ( t ) of the scattered electrical field Es, which contains information about the structure and the dynamics of the scattering particles [80]. 

FIG. 6 Frequency dependence of electric birefringence Kic from NaCMC solution, , and electric light scattering a from 8-FeOOH suspension, stabilized by addition... 

Figures 7 and 8 show variations in the electric light scattering effect from suspension, stabilized by NaPSS adsorption, with increasing concentration of salts of divalent (Mg2+) and trivalent (Al3+) counterions [18], One observes a steep decrease of the LF effect and some increase of the HF effect at concentration 2.5 X 10 M MgCl2 and 1.6 x 10 5 M A1C13, respectively. These amounts of low molecular salts are sufficient for Na+ to be fully replaced by Mg2+ and Al3+ from the polyion surface. The electro-optical effects vary in a different way when MgCl2 is added to the suspension with no NaPSS adsorbed on the particle surface—Figure 9. This by no means...

Recent development of laser-based instrumentation for electrophoretic mobility determination has made it possible to determine zeta potential of particles suspended in liquid media for systems that were difficult or impossible to study by classical techniques. These instruments measure electrophoretic mobilities by making direct velocity measurements of particles moving in an applied electric field by analyzing the Doppler shift of laser light scattered from the moving particles. Electrophoretic mobilities can then be converted into zeta potentials by use of standard equations 48-50),... 

R. A. M. Hikmet, Electrically induced light scattering from anisotropic gels with negative dielectric... 

Dyson-type equations have been used extensively in quantum electrodynamics, quantum field theory, statistical mechanics, hydrodynamic instability and turbulent diffusion studies, and in investigations of electromagnetic wave propagation in a medium having a random refractive index (Tatarski, 1961). Also, this technique has recently been employed to study laser light scattering from a macromolecular solution in an electric field. 

F. M. Leslie, C. M. Waters, Light scattering from nematic liquid crystal in the presence of an electric field. Mol. Cryst. Liq. Cryst. 1985, 123, 101-117. 

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