Nonlinear dielectric effect

When a strong static electric field is applied across a medium, its dielectric and optical properties become anisotropic. When a low frequency analyzing electric field is used to probe the anisotropy, it is called the nonlinear dielectric effect (NLDE) or dielectric saturation (17). It is the low frequency analogue of the Kerr effect. The interactions which cause the NLDE are similar to those of EFLS. For a single flexible polar molecule, the external field will influence the molecule in two ways firstly, it will interact with the total dipole moment and orient it, secondly, it will perturb the equilibrium conformation of the molecule to favor the conformations with the larger dipole moment. Thus, the orientation by the field will cause a decrease while the polarization of the molecule will cause an... 

Figure 2. Nonlinear dielectric effect constant ( 10 scm7SC 2moF ) of Br(CH2)n, Br at 25 °C. Points represent the experimental results of Chelkowski (19, 20). The solid and dashed lines are calculated with 4>s, = 120 ° and +80 °, respectively, for thefirst and last C-C bonds. (Reproduced with permission from Ref 6. Copyright 1981, American...

What is of interest here is the description of nonlinear dielectric effects with a linear procedure. Nonlinear dielectrics were introduced in the theory of liquids by Dogonatze and Kornyshev in the 1970s [21] the reformulation of the theory in more recent years by Basilevsky [22] permits its insertion in the whole machinery of the PCM version of the CS method. The reader is also referred to the contribution of Basilevsky and Chuev dedicated to non-local dielectric solvation models. 

The most pronounced evidence of the critical-like behavior in these compounds can be found by using the nonlinear dielectric effect (NDE). NDE is coupled via the 4-point correlation to multimolecular heterogeneities -fluctuations. It was shown in refs. that ... 

Figure 6. The temperature evolution of nonlinear dielectric effect in nitrobenzene. The red solid...

Drozd-Rzoska, A., Rzoska, S. J., andZiolo, J. (2008) Anomalous temperature behavior of nonlinear dielectric effect in supercooled nitrobenzene, Phys. Rev. Ell, 041501... 

Rzoska, S. J. (1993) Kerr effect and nonlinear dielectric effect on approaching the critical consolute point, Phys. Rev. E 48, 1136-1143... 

Rzoska, S. J., Chrapec, J., and Ziolo J. (1987) Fisher s renormalization for the nonlinear dielectric effect from isothermal measurements, Phys. Rev. A 36, 2885-2889... 

The motive for the present investigation is the question whether high fields promote proton jiomping in acid-base adducts and whether the reaction partners can be regarded as tautomers. According to conventional dielectric measurements by Polish authors such an equilibrium would be well-poised for the title compounds. Malecki analyzed the nonlinear dielectric effects in this system without concern for relaxation. ... 

Typical results are shown in Fig. 2. The most striking feature is chemical relaxation of the nonlinear dielectric effect. The loss data include a contribution... 

M. De Maeyer, R. Nackaerts, R. Ooms and L. Hellemans, "The Nonlinear Dielectric Effect and Chemical Relaxation a Happy Marriage",in Nonlinear Behaviour of Molecules, Atoms and Ions in Electric, Magnetic or Electromagnetic Fields, L. Neel ed., Elsevier, Amsterdam (in press). ... 

The nonlinear dielectric effect (NLDE) is then characterized by the quantity... 

Table 6 The Nonlinear Dielectric Effect in Nonpolar Liquids at 293 K...

The radii of organic ions are typically R = 4 A (see Section 4.2), which yields P = 0.925 eV. On a molecular scale, the ion is seen to be surrounded by shells of polarized solvent molecules (see Figure 20). Under the assumption that is independent of the electric field strength and that Rj n = Rsoivent/ can estimate the contribution of each shell to the total polarization energy by means of Equation 93. In the first shell 0.62 eV is expended, in the second shell 0.12 eV, and in the third shell 0.05 eV, or, in other words, 86% of the polarization energy is located within the first three layers of polarized molecules around the ionic core. If the nonlinear dielectric effect is taken into account (see Section 1.6), increases near the ionic core and an even greater fraction of the total polarization energy is concentrated in the first few solvation shells. 

Application of Born s equation to photoconductivity data implies that only electronic polarization processes occur. On a longer time scale, electrostriction leads to an increase of density and subsequently to an increase of the dielectric constant around the ion. Furthermore, for the first few shells of atoms or molecules around the charge, nonlinear dielectric effects must be considered (see Section 1.6). The Bom equation is derived under the assumption of a continuum model of the dielectric. A more adequate approach would take into account the positions of the atoms or molecules around the ion. Such attempts have been made for organic solids (Sato et al., 1981) and rare gas solids (Lyons and Sceats, 1970). 

The permittivity of liquids at very high fields is given by the nonlinear dielectric effect ... 

Another quantity that should be considered in this context is the electric field dependence of the permittivity of the solvent, noting the huge electrical fields exerted by ions in their vicinity. This topic was already briefly brought up in Section 2.3, but deserves fuller attention. The following expression [25] relates the permittivity of the solvent to the electric field strength in terms of the nonlinear dielectric effect ... 

F. Nonlinear Dielectric Effect Studies V. Concluding Remarks References... 

The nonlinear dielectric effect (NDE) is an important tool for studying the properties of the isotropic-nematic transition. The NDE is the measure of changes in electric permittivity due to the application of a strong electric field E Ae = - e, where and e... 

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