Diffusing-wave spectroscopy: The technique and some applications

D. A. Weitz, Hu Gang, D. J. Pine, J. X. Zhu, D. J. Durian

Research output: Contribution to journalArticle

Abstract

We discuss the en tension of dynamic light scattering to very strongly scat­tering media, where the propagation of light is described by the diffusion approximation, allowing the distribution of the light paths to be deter­mined. The temporal evolution of the length of each of these paths, due to the dynamics of the scattering medium, is calculated, and an expression for the temporal autocorrelation function of the intensity fluctuations of the scattered light is obtained. This relates the measured decay of the autocor­relation function to the dynamics of the medium. This technique is called diffusing wave spectroscopy (DWS). To extend its utility, we consider the consequences of interactions between the scattering particles on the light scattering. To illustrate its applications, we consider several examples of new physics that can be investigated using DWS. We study the transient nature of hydrodynamic interactions between a particle and the surround­ing fluid. We are able to probe the decay of the velocity correlation func­tion of the particles, and we demonstrate its algebraic decay, with a t-3/2time dependence. We also show that the time-dependent self diffusion coef­ficient exhibits an unexpected scaling behavior, whereby all the data, from samples of different volume fractions, can be scaled onto a single curve. Finally, we discuss the applications of DWS to the study of the dynamics of foams, and show how it can be used to probe the rearrangement of the bubbles within the foam as they coarsen.

Original languageEnglish (US)
Pages (from-to)610-621
Number of pages12
JournalPhysica Scripta
Volume1993
Issue numberT49B
DOIs
StatePublished - Jan 1 1993

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics
  • Mathematical Physics
  • Condensed Matter Physics

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