Chapter 4. Dielectric relaxation in solutions

9 Dielectric relaxation in solutions

“…155,157 In previous studies the extracted fast relaxation time, t 3 , was at the short-time limit of the accessible time window. 1 Therefore, it is not surprising that recent measurements on methanol, ethanol, and propan-1-ol in the terahertz range yield smaller values, t 3 ≈ 0.2 ps. 74 However, the triple-Debye relaxation of the three alcohols is corroborated, although the amplitudes and relaxation times of the lowfrequency processes are affected by the limited frequency range of 0.06 @ n/THz @ 1.5.…”

“…However, the distinction between the dipolar aprotic solvents DMA and DMF, the chain-forming NMF, and the networkforming FA is far more important, 5 corroborating previous investigations. 1,293 For DMA and DMF, as well as for acetonitrile, 288 N-methyl-2-pyrrolidone, tetramethylurea, and ethyl acetate, 294 the increase of t s with concentration parallels the increase of solution viscosity. The deduced effective volume of rotation for the solvent molecule is generally very small, which indicates that the effect of the solvated ions on the dynamics of the bulk solvent is limited.…”

“…For conducting systems, such as electrolyte solutions, an additional contribution must be considered due to diffusive charge transport which is expressed by the complex conductivity k(n) = kA(n) 2 ikB(n). 1,23 Only ĥ(n) is accessible by experiment. The dielectric and conductivity contributions are linked by the relations…”

“…Generally, the fluctuation of the induced polarization, P a (t), determined by the intra-molecular polarizability, is a very rapid phenomenon compared to the changes of the orientational polarization, P m (t), which arise from molecular motions connected with the reorientation of permanent molecular dipole moments mi . 1,23 Therefore it is convenient to express P a (t) by the 'infinite frequency' permittivity e H , allowing one to write the total permittivity of a sample as ê(n) = (e 2 e H ) F(n) + e H…”

Dielectric properties of liquid ethanol. A computer simulation study

“…In the case of monohydric alcohols, experimental data are usually analyzed by considering an empirical model which consists of three Debye-type processes. 33 With this assumption, ⑀͑ ͒ can be separated into the real and imaginary parts…”