The relaxation of the nonlinear dielectric effect

• Published in: Journal of molecular structure Vol. 436; pp. 595 - 604
• Main Author: Maz.xl;lecki, Jerzy
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 15.12.1997
• Subjects: Chemical relaxation; Langevin effect; Non-linear dielectric effect; Non-linear dielectric effect; Langevin effect; Chemical relaxation
• ISSN: 0022-2860; 1872-8014
• DOI: 10.1016/S0022-2860(97)00118-X

The nonlinear dielectric effect of polar liquid contains of two main contributions—the negative change ( Δε L < 0) in electric permittivity related to orientation—the Langevin effect, and positive one ( Δε CH > 0) related to shift in molecular equilibria present in the sample—the chemical effect. Both contributions reveal specific relaxations observed usually in well separated frequency regions. Relaxation of Langevin effect takes place close to orientation relaxation time ( τ or) and is described by the specific relaxation functions. In this case the third harmonic contribution to relaxation can also be observed. Relaxation related to the chemical reaction, e.g. to equilibria leading to formation of very labile molecular complexes, intramolecular conformations and so on, is observed in two separate bands. The first region of chemical relaxation is described by pure Debye model and is associated to the rate of a given chemical reaction. The experimentally determined relaxation time τ CH can be used to calculate the rate constants of fast molecular equilibria. The second relaxation band of chemical effect occurs in dielectric relaxation region and is similar to the relaxation of Langevin effect.