Transient electric birefringence

A dilute suspension of electrically and optically anisotropic colloidal particles becomes birefringent when subjected to an electric field. In random orientation the suspension is optically isotropic but when the grains align with a uniform electric field the suspension becomes anisotropic in particular the effective refractive index of the ordered suspension parallel to the field direction differs from its refractive index 

Experimentally, a colloidal system, in random orientation, is illuminated with polarized light. The system is subjected to an electric field that aligns the particles due to the interaction between the field and any permanent dipole or electrical polarizability of the particles. The birefringence grows as the particles align when the field is removed the birefringence decays as the particles revert to random orientation. 

For a monodisperse suspension the decay rate can be described by a first order rate equation. For a polydisperse suspension the decay rate is a sum of exponentials. Measurement of the decay rate permits computation of particle size [338]. 

Haseler and Hinds used this procedure to determine the size distribution of anisometric silver halide ciystals using an instrument that they developed called an electric field birefringece. They found that the technique was capable of good accuracy and high precision [339]. 

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Figure 4.1. Time scales for rotational motions of long DNAs that contribute to the relaxation of the optical anisotropy r(t). Experimental methods used to study these motions in different time ranges are also indicated along with the authors and dates of some early work in each case. FPA, Fluorescence polarization anisotropy (Refs. 15, 18-20, and 87) TPD, transient photodichroism (Refs. 28 and 62) TEB, transient electric birefringence (Refs. 26 and 27) DDLS, depolarized dynamic light scattering (Ref. 116) TED, transient electric dichroism (Refs. 25, 115, and 130) Microscopy, time-resolved fluorescent microscopy (Ref. 176).

Dynamic Light Scattering and Transient Electric Birefringence Study of Poly(vinyI chloride) Micrc els... 

In this study, has been investigated by means of quasi-elastic light scattering and transient electric birefringence the effect of the quenching concentration on the structure of the PVC aggregates as well as the thermal stability of these aggregates. 

Table I. Transient electric birefringence parameters for PVC solutions at C = 10 g cm...

A (1.6). The filled symbols correspond to the Dq values calculated from the transient electric birefringence results (cf. text). 

We have also reported on the ordinate axis of Fig.3 the values of the translational diffusion coefficient calculated from radius values measured by transient electric birefringence, using ... 

D.F. Nicoli, J.G. Elias and D. Eden, Transient electric birefringence study of CTAB micelles implications for rodlike growth, J. Phys. Chem. 85 (1981) 2866-2869. 

Colloidal dispersions suspensions and aggregates Viscosity and transient electric birefringence study of clay colloidal aggregation. Physical Review E 65, 21407-21500... 

It is necessary to mention that Eqs. (4.375)-(4.377) are close analogs of the expressions derived by O Konski et al. while studying transient electric birefringence in solutions. The only difference between our Eqs. (4.376) and (4.377) and those of Ref. 149 is in the representation of the self-similar argument in Ref. 149 it is )tjxg, since that paper deals with a transient process. 

Photon Correlation Spectroscopy, Transient Electric Birefringence, and Characterization of Particle Size Distributions in Colloidal Suspensions... 

In colloidal suspensions of anisotropic particles, the static structure factor plays a prominent role in particle size analysis. We have used transient electric birefringence (TEB) and electron microscopy, in addition to laser light scattering, to correlate our analysis of particle size distributions of bentonite suspensions. The complementary nature of TEB and photon correlation spectroscopy (PCS) in particle size analysis will be discussed. 

Quasi-elastic Light Scattering Conversion3 Transient Electric Birefringence Viscosity Corrected to w, 20°C Sense of Biref. 

D and D are the weight- and z-averaged diffusion coefficients, respectively. Weight averaging is obtained directly by transient electric birefringence. 

The behavior of water in oil microemulsions has been studied using different techniques light scattering, electrical conductivity, viscosity, transient electrical birefringence, ultrasonic absorption. All these experiments lead us to propose a picture of the microemulsions structure which assignes an important role to the fluidity of the interfacial region. 

Wesenberg GE, Vaughan WE. Theory of the transient electric birefringence of rod-like polyions coupling of rotational and counterion dynamics. J Chem Phys 1987 87 4240-4241. 

Submicrosecond components in transient electric birefringence Depends on length 87... 

Figure 1 Block diagram of a typical electrical birefringence apparatus using either square-pulse (for transient electrical birefringence) or oscillating field (for dynamic electrical birefringence) perturbations. P, polarizer A, analyzer A/4, quarter-wave retardation plate P.S., power supply P.M.T., photomultiplier tube HP-214A, wave-form generator. (Reprinted with permission from Ref. 41. Copyright 1994 American Chemical Society.)...

The block diagram of a typical transient electrical birefringence apparatus is shown in Fig. 1. The sample solution is located between the two electrodes (3 mm apart) of the Kerr cell, which is equipped with windows and has an optical path length 1 — 5 cm. The high voltage (up to a few kilovolts) square pulse is produced by a pulse generator (Cober 605P), with the rise and fall times of the pulse < 50 ns. 

Figure 3 Typical oscilloscope traces of the light intensity signal (top trace scale 80 mV/1 ms) due to transient electrical birefringence and of the attenuated perturbation square pulse (bottom trace scale 400 mV/1 ms). Note that in this example the forward and reverse relaxation signals are not symmetrical.

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