Chandra, Amalendu ; Bagchi, Biman (2000) Frequency dependence of ionic conductivity of electrolyte solutions Journal of Chemical Physics, 112 (4). pp. 18761886. ISSN 00219606

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Official URL: http://link.aip.org/link/?JCPSA6/112/1876/1
Related URL: http://dx.doi.org/10.1063/1.480751
Abstract
A theory for the frequency dependence of ionic conductivity of an electrolyte solution is presented. In this theory contributions to the conductivity from both the ion atmosphere relaxation and the electrophoretic effects are included in a selfconsistent fashion. Mode coupling theory, combined with timedependent density functional theory of ion atmosphere fluctuations, leads to expressions for these two contributions at finite frequencies. These expressions need to be solved selfconsistently for the frequency dependence of the electrolyte friction and the ion conductivity at varying ion concentrations. In the limit of low concentration, the present theory reduces exactly to the wellknown DebyeFalkenhagen (DF) expression of the frequencydependent electrolyte friction when the nonMarkovian effects in the ion atmosphere relaxation are ignored and in addition the ions are considered to be pointlike. The present theory also reproduces the expressions of the frequencydependent conductivity derived by Chandra, Wei, and Patey when appropriate limiting situations are considered. We have carried out detailed numerical solutions of the selfconsistent equations for concentrated solutions of a 1:1 electrolyte by using the expressions of pair correlation functions given by Attard. Numerical results reveal that the frequency dependence of the electrolyte friction at finite concentration can be quite different from that given by the DF expression. With the increase of ion concentration, the dispersion of the friction is found to occur at a higher frequency because of faster relaxation of the ion atmosphere. At low frequency, the real part of the conductivity shows a small increase with frequency which can be attributed to the wellknown DebyeFalkenhagen effect. At high frequency, the conductivity decreases as expected. The extensions of the present theory to treat frequencydependent diffusivities of charged colloid suspensions and conductivity of a dilute polyelectrolyte solution are discussed.
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ID Code:  4240 
Deposited On:  13 Oct 2010 09:09 
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