Electric Polarization of Onsager Fluids. I. Dipole Polarization. 1. Electric Moments of Free Molecules

Abstract

An attempt was made to modify the model Onsager theory. A polarizable molecular dipole enclosed in a spherical cavity is substituted for a rigid one submerged in the polarizable medium which fills the cavity. The local dielectric permittivity of the Heaviside type is replaced for the oscillating, rapidly damping function of the Fresnel integral. The analytical expressions deduced allow to estimate dipoles of free molecules, starting from the results of dielectrometry of polar fluids. The obtained values are as close as possible to the experimental data on a great variety of pure organic liquids.

Electric Polarization of Onsager Fluids. II. Birefringence. 1. Kerr Constants of Pure Substances

“…Mutual orientations of {σ} and {i} are determined by guiding cosines cos[i, σ ] = (i, σ), related to Euler's angles {r} = (φ, ψ, θ) by known expressions. Then, molecular polarization contributions along the external field can be rewritten according to (1) as…”

“…The paper presents the outcomes of theoretical description of the Kerr effect in liquids according to Langevin-Born employing the local field model that we have (797) worked out in the previous publications [1]. Experimental part of it comprises the comparison of the EB constants computed by the expressions derived with the observed ones measured for liquid organic media.…”

Electric Polarization of Onsager Fluids. 1. Dipole Polarization. 2. Binary Solutions of Organic Compounds

“…In particular, the modified Onsager theory presented in our previous report [1] The factors g, t and their derivatives with respect to the dissolved substance concentration x2 arc specified by the manner of description of internal field in condensed dielectrics. The Onsager body radii ai in the term which defines ai and ti are taken in accordance with [2] in the form a3 = (0.86 T 0.03) r3 , where r are the Van der Waals radii of molecules of solution components.…”

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Set forth in the previous report [1], the continual theory of dipole polarization of molecular fluids, which suggests substitution of the rigid Onsager sphere for the polarizable body and takes into consideration electric induction of this body and its nearest surroundings, is extended in this paper to binary solutions with diverse polarities. Dipole moments of free molecules of dissolved substances were calculated from experimental data of dielectrometry of a large number of extremely diluted organic substances and are close to the corresponding gaseous phase values.

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