A light Scattering Technique for Studying Brownian Motion
Technical rept. Sep 1970-May 1971
EDGEWOOD ARSENAL ABERDEEN PROVING GROUND MD
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The purpose of the work was to study the light scattered from a simple statistical medium that consisted of a monodispersed ensemble of spherical, Brownian particles. The light from a helium-neon laser operating at a wavelength of 632.8 nm was scattered from a dilute water suspension of the particles, which are polystyrene spheres of diameter 0.557 micrometers. The spectrum of the scattered light is a very narrow Lorentzian whose half width at half height is related to the diffusion constant of the particles. An experiment that employs the technique of pulse interval analysis to analyze the scattered light spectrum is described in detail. The results of this experiment yielded a spectral linewidth that is caused not only by the diffusive motion, but also by the convective motion of the particles.
- Physical Chemistry