Flow Light Scattering. I. Theoretical Principles of the Effect and Apparatus for Its Measurement

Abstract

A brief introduction is given into the theory of radiation scattering by rigid spheroids and deformable random coils dispersed or dissolved in a liquid medium subjected to flow at a well-defined velocity gradient. The theory is limited, in the former instance, to spheroids whose largest dimension does not exceed 13 of the wavelength of the incident radiation. It is shown that the radiation scattering increment produced by flow makes it possible to determine not only the axial ratio, as obtainable by streaming birefringence, but also the numerical values of semimajor and semiminor axis of a spheroid provided two orthogonal components of incident linearly polarized light are used. Essentials of the construction and operation of an apparatus designed for the study of hydrodynamic radiation scattering are described.

Picosecond polarized fluorescence studies of anisotropic fluid media. II. Experimental studies of molecular order and motion in jet aligned rhodamine 6G and resorufin solutions

“…Traditionally this has been achieved in two distinct ways, first, by the imposition of shear forces arising from confined fluid flow [3][4][5][6][7] and second by the use of an applied dc electric field on a polar or anisotropically polarizable molecular system. [8][9][10] The result of these approaches is to create an energy difference between differing molecular orientations ͑,͒ defined relative to a laboratory axis system, which for a system in thermal equilibrium with its surroundings gives rise to the well known expression for the orientational distribution function,…”

Structure and properties of macromolecules in shearflow

“…They allow the measurement of the scattering intensity distribution in a plane of flow (plane between the direction of flow and the direction of the velocity gradient) [2]. To make such measurements possible, during the past years a number of experimentors [3][4][5] have used visible light to investigate high molecular substances. If the wavelength of the incoming light is in the range of the dimensions of the scattering particles, destructive interference occurs, which provides additional information about the direct measurement of particle orientation and deformation.…”

“…Such measurements give us information about the dimensions of the scattering particles and their orientation and/or deformation by shear stress. The measuring apparatuses described so far are only able to register the scattered light in the plane of K 820 flow [5]., i. e. within the relatively small angular range of + 20 ~ around the direction of the shear gradient [3,4]. To make such measurements possible, during the past years a number of experimentors [3][4][5] have used visible light to investigate high molecular substances.…”

Recent trends in classical light scattering from polymer solutions

“…[31][32][33], but rather few investigations via L,S, have been reported (Ref. [34][35][36]. Heller et al (Ref.…”

“…Heller et al (Ref. 34,35) have constructed an elaborate apparatus with a laser light source, the disturbance in recorded scattering due to minute air bubbles being overcome by filling the cell slowly under gravity feed. Cottrell et al (Ref.…”