Theory of Dielectric Relaxation in Polar Liquids

Abstract

The theory of dielectric relaxation in a model polar liquid is developed and applied to experimental data. The model is a spherical Onsager cavity, with a uniform dielectric background described by the high frequency limit ε∞ and containing a permanent point dipole. The dipole moment undergoes rotational Brownian motion in the cavity. Dielectric friction on the rotating dipole is taken into account and leads to a frequency-dependent relaxation time. Earlier theoretical results, obtained first by Klug, Kranbuehl, and Vaughn and by Fatuzzo and Mason, are rederived. When the rotational Brownian motion is spherically isotropic, approximate Debye relaxation is found. When the rotational Brownian motion of the dipole is restricted to a constant angle with respect to some fixed axis, approximate Davidson–Cole relaxation is found. Experimental data on glycerol and i-amylbromide are analyzed this way.

Surface-Assisted Transient Displacement Charge Technique. II. Effect of Gases on Photoinduced Charge Transfer in Self-Assembled Monolayers

“…The latter proceeds with the rate k q [O 2 ], according to reaction (17), while reaction (16) is not energetically feasible 10,11 since the S-T gap in coumarin is smaller than the excited state energy of . Figure 7 demonstrates the dipole signals of covalently bound coumarin SAM and physisorbed coumarin 460 on quartz substrates in air and in oxygen.…”

Rotational Dynamics of Nonpolar and Dipolar Molecules in Polar and Binary Solvent Mixtures

“…Initial investigations were closely intertwined with the theories of dielectric dispersion in pure solvents (Titulaer and Deutch, 1974;Bottcher and Bordewijk, 1978;Cole, 1984). Beginning with the first paper to relate the dielectric friction to rotational motion published by Nee and Zwanzig in 1970, a number of studies have made improvements to the Nee-Zwanzig approach (Tjai et al, 1974;Hubbard and Onsager, 1977;Hubbard and Wolynes, 1978;Bordewijk, 1980;McMahon, 1980;Brito and Bordewijk, 1980;Bossis, 1982;Madden and Kivelson, 1982;Felderhof, 1983;Nowak, 1983;van der Zwan and Hynes, 1985;Alavi et al, 1991a,b,c;Alavi and Waldeck, 1993). These have included the electrohydrodynamic treatment which explicitly considers the coupling between the hydrodynamic (viscous) damping and the dielectric friction components.…”

“…It is documented that the SED model correctly predicts the linear dependence of the rotational reorientation times on the solvent viscosity for polar and cationic dyes dissolved in polar and non polar solvents (Chuang and Eisenthal, 1971;Fleming et al, 1976;Porter et al, 1977;Moog et al, 1982;Spears and Cramer, 1978;Millar et al, 1979;von Jena and Lessing, 1979a, b;Rice and KenneyWallace, 1980;Waldeck and Fleming, 1981;Dutt et al, 1990;Alavi et al, 1991a, b, c;Krishnamurthy et al, 1993;Dutt et al, 1998) that have been interpreted using dielectric fiction theories. The dielectric friction can be modeled using continuum theories of NeeZwanzig (NZ) (Nee and Zwanzig, 1970), which treats the solute as a point dipole rotating in a spherical cavity, Alavi-Waldeck (AW) (Alavi and Waldeck, 1991b;1993) model which is an extension of the NZ theory where the solute is treated as a distribution of charges instead of point dipole and the semiempirical approach of van der Zwan and Hynes (vdZH) (van der Zwan and Hynes, 1985) in which fluorescence Stokes shift of the solute in a given solvent is related to dielectric friction. Conversely, the results of neutral and nonpolar solutes deviate significantly from the hydrodynamic predictions at higher viscosities (Waldeck et al, 1982;Canonica et al, 1985;Phillips et al, 1985;Courtney et al, 1986;Ben Amotz and Drake, 1988;Roy and Doraiswamy, 1993;Williams et al, 1994;Jiang and Blanchard, 1994;Anderton and Kauffman, 1994;Brocklehurst and Young, 1995;Benzler and Luther, 1997;Dutt et al, 1999;Ito et al, 2000;Inamdar et al, 2006).…”

Interconversion algorithm between mechanical and dielectric relaxation measurements for acetate ofcis- andtrans-2-phenyl-5-hydroxymethyl-1,3-dioxane

“…This value of a corresponds to the slope of the loss permittivity at lower frequency. The definition of rotational viscosity is according to that obtained by Nee and Zwanzig [15] based on the fluctuation-dissipation theorem with η * rot (ω) proportional to the dielectric friction. They considered a rotational spherical molecule in a molecular environment acted on by a definite torque produced by the external electric field.…”