Diffusing wave spectroscopy of dense colloids: Liquid, crystal and glassy states

Sanyal, Subrata and Sood, Ajay K (1995) Diffusing wave spectroscopy of dense colloids: Liquid, crystal and glassy states. In: Pramana - Journal of Physics, 45 (1). pp. 1-17.

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Abstract

Using intensity autocorrelation of multiply scattered light, we show that the increase in interparticle interaction in dense, binary colloidal fluid mixtures of particle diameters 0.115µm and 0.089µm results in freezing into a crystalline phase at volume fraction? of 0.1 and into a glassy state at?=0.2. The functional form of the field autocorrelation functiong (1)(t) for the binary fluid phase is fitted to exp[??(6k 0 2 D eff t)1/2] wherek 0 is the magnitude of the incident light wavevector and? is a parameter inversely proportional to the photon transport mean free pathl*. TheD eff is thel* weighted average of the individual diffusion coefficients of the pure species. Thel* used in calculatingD eff was computed using the Mie theory. In the solid (crystal or glass) phase, theg (1)(t) is fitted (only with a moderate success) to exp[??(6k 0 2 W(t))1/2] where the mean-squared displacementW(t) is evaluated for a harmonically bound overdamped Brownian oscillator. It is found that the fitted parameter? for both the binary and monodisperse suspensions decreases significantly with the increase of interparticle interactions. This has been justified by showing that the calculated values ofl* in a monodisperse suspension using Mie theory increase very significantly with the interactions incorporated inl* via the static structure factor.

Item Type:	Journal Article
Publication:	Pramana - Journal of Physics
Publisher:	Indian Academy of Sciences
Additional Information:	Copyright of this article belongs to Indian Academy of Sciences.
Keywords:	Colloids;dynamic light scattering;crystal and glass transitions
Department/Centre:	Division of Physical & Mathematical Sciences > Physics
Date Deposited:	15 Jun 2011 08:43
Last Modified:	15 Jun 2011 08:43
URI:	http://eprints.iisc.ac.in/id/eprint/37551

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