21 November 1997 Polydispersities by dynamic light scattering
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Abstract
We study the detectional theory of polydispersities for dilute suspension of optical and size polydisperse spherical particles for which the Rayleigh-Gans-Debye approximation is valid. Tho develop the theory a concentric core-shell hard sphere model is adopted, in which particles possess a continuous variation in the core size and shell thickness. The thickness of shell is directly proportional to the radius of core, thus giving rise to a distribution in the particle refractive indices. We assume the shell thickness L equals (alpha) R, where (alpha) < 1 and is a constant. We extend the 'measured' dynamic structure factor to the general case where optical and size poly-dispersed are combination and a new 'measured' dynamic structure factor to the general case where optical and size poly-dispersed are combination and a new 'measured' static structure factor Sm (K) is derived. We analyze the dependence of the average scattered intensity I(q) and the effective diffusion coefficient De(q) which is obtained from the first cumulant measured by dynamic light scattering in the case of the refractive index of the solvent and the refractive index of the shell are matched, i.e., nm$ equals n(subscript s, on scattering vector q. Under favorable conditions it should be possible to measure small polydispersities.
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Yixin Zhang, Qiang Xu, Tuo Zhu, Xiaowu Ni, "Polydispersities by dynamic light scattering", Proc. SPIE 3172, Optical Technology in Fluid, Thermal, and Combustion Flow III, (21 November 1997); doi: 10.1117/12.279767; https://doi.org/10.1117/12.279767
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