Transient electric birefringence dynamics

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... 

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. 

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 usefulness of electrical response measurements of solutions is not limited to effects linear in applied field. Transient birefringence induced by polarizing electric fields (the transient or dynamic Kerr effect) has given valuable information about biopolymers in solution the effect must by symmetry be an even function of E(t), beginning with terms in E (t). In both cases, a response theory treatment of transient behavior meets with difficulties not encountered in linear problems, but recent progress in deriving correlation function expressions for such effects is described in III. 

This electro-optical effect, commonly observed as transient changes in optical birefringence of a solution following application, removal, or reversal of a biasing electric field E(t), has been used extensively as a probe of dynamics of blopolymer solutions, notably by O Konski, and is a valuable tool because it gives information different in form, but related to, results from conventional dielectric relaxation measurements. The state of the subject to 1975 has been comprehensively presented in two review volumes edited by O Konski (25). The discussion here is confined to an outline of a response theory treatment, to be published in more detail elsewhere, of the quadratic effect. The results are more general than earlier ones obtained from rotational diffusion models and should be a useful basis for further theoretical and experimental developments. 

Since 1875, thanks to Kerr s discovery [ 1], it is known that a static electric field can induce a modification of the optical properties of a liquid. Many years later researchers found out that also an optical electromagnetic field was capable of producing a measurable modification of the dielectric properties, inducing a hirefiringence effect the first experimental observation of the optical Ken-effect (OKE) was reported in 1963 [2]. After few years, with the introduction of the first pulsed lasers, spectroscopists discovered the chance to induce in a material a transient birefringence and to measure its relaxation toward the equiUhrium [3]. They also realized that this could be a relevant new spectroscopic tool able to collect new information on the dynamical processes present in the material. The spectroscopic research, worked out in the following years, confirmed this forecast beyond the expectations. Two important experimental improvements of this spectroscopic technique have been made. On one hand, the pulsed laser sources have become able to produce very short pulses of high... 

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