Diffusion of Small Solute Particles in Viscous Liquids: Cage Diffusion, a Result of Decoupling of Solute鈥揝olvent Dynamics, Leads to Amplification of Solute Diffusion

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• 作者：Sayantan Acharya ; Manoj K. Nandi ; Arkajit Mandal ; Sucharita Sarkar ; Sarika Maitra Bhattacharyya
• 刊名：Journal of Physical Chemistry B
• 出版年：2015
• 出版时间：August 27, 2015
• 年：2015
• 卷：119
• 期：34
• 页码：11169-11175
• 全文大小：398K
• ISSN：1520-5207

文摘

We study the diffusion of small solute particles through solvent by keeping the solute鈥搒olvent interaction repulsive and varying the solvent properties. The study involves computer simulations, development of a new model to describe diffusion of small solutes in a solvent, and also mode coupling theory (MCT) calculations. In a viscous solvent, a small solute diffuses via coupling to the solvent hydrodynamic modes and also through the transient cages formed by the solvent. The model developed can estimate the independent contributions from these two different channels of diffusion. Although the solute diffusion in all the systems shows an amplification, the degree of it increases with solvent viscosity. The model correctly predicts that when the solvent viscosity is high, the solute primarily diffuses by exploiting the solvent cages. In such a scenario the MCT diffusion performed for a static solvent provides a correct estimation of the cage diffusion.