On the non-exponentiality of the dielectric Debye-like relaxation of monoalcohols

Abstract

We have investigated the Debye-like relaxation in a series of monoalcohols (MAs) by broadband dielectric spectroscopy and thermally stimulated depolarization current techniques in order to get further insight on the time dispersion of this intriguing relaxation. Results indicate that the Debye-like relaxation of MAs is not always of exponential type and conforms well to a dispersion of Cole-Davidson type. Apart from the already reported non-exponentiality of the Debye-like relaxation in 2-hexyl-1-decanol and 2-butyl-1-octanol, a detailed analysis of the dielectric permittivity of 5-methyl-3-heptanol shows that this MA also presents some extent of dispersion on its Debye-like relaxation which strongly depends on the temperature. Results suggest that the non-exponential character of the Debye-like relaxation might be a general characteristic in the case of not so intense Debye-like relaxations relative to the α relaxation. Finally, we briefly discuss on the T-dependence and possible origin for the observed dispersion.

Supramolecular Self-Assembly of Monocarboxydecyl-Terminated Dimethylsiloxane Oligomer

“…All these characteristics, observed above 230 K, i.e., before any thermal transition occurs, allow attributing this dielectric relaxation of o-DMS-DCOOH as originated from the fluctuations of the H-bonds among carboxyl units. This assignment is supported by the fact that a Debye-like relaxation shape and a rapidly decreasing relaxation strength are typically found for the slowest dielectric relaxation of simple monoalcohols, a relaxation that is commonly attributed to the fluctuations of the H-bond network …”

“…This assignment is supported by the fact that a Debye-like relaxation shape and a rapidly decreasing relaxation strength are typically found for the slowest dielectric relaxation of simple monoalcohols, a relaxation that is commonly attributed to the fluctuations of the H-bond network. 25 Clear changes in the behavior of the three parameters occur below the transition range. The most dramatic one is a fast increase of the dielectric relaxation strength, the product TΔϵ reaching a plateau-like behavior below 190 K. The value of TΔϵ is a quantity directly related with both number-density and orientation-correlations of the molecular dipoles participating in the relaxation process.…”

Intermolecular Cross-Correlations in the Dielectric Response of Glycerol

“…Thus, the BDS spectra split into a broad self-correlation part and a more narrow cross-correlation part. Compared to monohydroxy alcohols the latter contribution is slightly more stretched, and it should be noted that in some monohydroxy alcohols the Debye-like relaxation also appears to be slightly broadened 43 , in particular when the latter is close to the α-relaxation indicating rather small supramolecular structures that comprise 3 The light scattering data from Fig. 1 were shifted with respect to the dielectric data with a common factor determined at 190K by overlapping the high-frequency wing of the α-relaxation in both methods.…”

Inflection point in the Debye relaxation time of 2-butyl-1-octanol

“…where ∆ D is the relaxation strength, ω = 2πf the angular frequency, and τ D the relaxation time. However, it should be mentioned that some recent reports indicate a slight broadening of the relaxation 3,4 , and promote fitting with either the empirical Havriliak-Negami (HN) (2) (where α and β are the symmetric and the asymmetric broadening parameters, respectively), or with the a) erik.thoms@smcebi.edu.pl b) marian.paluch@us.edu.pl closely related Cole-Davidson (CD) equation 6 (Eq. 2 with α = 1).…”