Theory of light scattering from a system of interacting Brownian particles
Starting from a N-particle diffusion equation for a system of N interacting spherical Brownian particles, a non-linear transport equation for concentration fluctuations δc(r, t) of the particles is derived. This dynamic equation is transformed into a hierarchy of equations for retarded propagators of increasing numbers of concentration fluctuations. A cluster expansion to lowest order in the average concentration results in a set of two coupled equations. The spectrum of light scattered by the interacting particles is in general not a Lorentzian, due to the non-linear term in the transport equation. For small scattering wave vectors k the width is D(ω)k2, where ω is the transferred frequency. It is shown that D(0) = De, the effective diffusion coefficient. For a hardcore interaction potential the spectrum is Lorentzian and it is found that De = D0(1 + φ), where D0 is the diffusion constant for independent particles and φ the volume concentration of Brownian particles.
Year of publication: |
1976
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Authors: | Hess, W. ; Klein, R. |
Published in: |
Physica A: Statistical Mechanics and its Applications. - Elsevier, ISSN 0378-4371. - Vol. 85.1976, 3, p. 509-527
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Publisher: |
Elsevier |
Saved in:
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