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Anomalous orientational relaxation of solute probes in binary mixtures

Bhattacharyya, Sarika and Bagchi, Biman (2001) Anomalous orientational relaxation of solute probes in binary mixtures. In: Journal of Chemical Physics, 115 (19). pp. 9065-9071.


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The orientation of a solute probe in a binary mixture often exhibits multiple relaxation times at the same solvent viscosity but different compositions [Beddard et al., Nature (London) 294, 145 (1981)]. In order to understand this interesting observation, we have carried out (NPT) molecular dynamics simulation study of rotation of prolate ellipsoids in binary mixtures. The simulations show that for a broad range of model parameters the experimental behavior can be reproduced. The plot of orientational relaxation time versus the solvent viscosity, the latter changed by varying the composition, shows a nonmonotonic viscosity dependence. The nature of the plot is found to depend on the system parameters, especially on the solute solvent interactions. A mode coupling theoretical analysis of this complex dependence of the rotational relaxation time tR on the binary viscosity h is presented. The theory can qualitatively explain the origin of the multiple relaxation time at the same viscosity.

Item Type: Journal Article
Publication: Journal of Chemical Physics
Publisher: American Institute Of Physics
Additional Information: The DOI is currently only displayed. Copyright for this article belongs to American Institute of Physics (AIP)
Keywords: Binary Mixture;Orientational Relaxation
Department/Centre: Division of Chemical Sciences > Solid State & Structural Chemistry Unit
Date Deposited: 16 Sep 2004
Last Modified: 19 Sep 2010 04:12
URI: http://eprints.iisc.ac.in/id/eprint/347

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