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Evidence of clustering in an aqueous electrolyte solution: a small-angle X-ray scattering study

Jacob, J and Kumar, A and Asokan, S and Sen, D and Chitra, R and Mazumder, S (1999) Evidence of clustering in an aqueous electrolyte solution: a small-angle X-ray scattering study. In: Chemical Physics Letters, 304 (3-4). pp. 180-186.

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The work reported hen was motivated by a desire to verify the existence of structure - specifically MP-rich clusters induced by sodium bromide (NaBr) in the ternary liquid mixture 3-methylpyridine (Mf) + water(W) + NaBr. We present small-angle X-ray scattering (SAXS) measurements in this mixture. These measurements were obtained at room temperature (similar to 298 K) in the one-phase region (below the relevant lower consolute points, T(L)s) at different values of X (i.e., X = 0.02 - 0.17), where X is the weight fraction of NaBr in the mixture. Cluster-size distribution, estimated on the assumption that the clusters are spherical, shows systematic behaviour in that the peak of the distribution shifts rewards larger values of cluster radius as X increases. The largest spatial extent of the clusters (similar to 4.5 nm) is seen at X = 0.17. Data analysis assuming arbitrary shapes and sizes of clusters gives a limiting value of cluster size (- 4.5 nm) that is not very sensitive to X. It is suggested that the cluster size determined may not be the same as the usual critical-point fluctuations far removed from the critical point (T-L). The influence of the additional length scale due to clustering is discussed from the standpoint of crossover from Ising to mean-field critical behaviour, when moving away from the T-L.

Item Type: Journal Article
Publication: Chemical Physics Letters
Publisher: Elsevier Science
Additional Information: Copyright of this article belongs to Elsevier Science.
Department/Centre: Division of Physical & Mathematical Sciences > Instrumentation Appiled Physics
Division of Physical & Mathematical Sciences > Physics
Date Deposited: 17 Jul 2009 10:37
Last Modified: 19 Sep 2010 05:27
URI: http://eprints.iisc.ac.in/id/eprint/19313

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