High-frequency dielectric spectroscopy on glycerol

Lunkenheimer, P.; Pimenov, A.; Schiener, B.; Böhmer, Roland; Loidl, A.

doi:10.1209/epl/i1996-00387-4

Cited by 102 publications

(101 citation statements)

References 17 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This alignment seems to be considerably reduced, with the net effect that the relaxation spectra of iso-amyl bromide in 2-methaylpentane becomes like that of an amorphous polymer with a broad distribution of relaxation times 27 and a variety of other molecular liquids. 5,8,9 As mentioned earlier here, a variety of studies on supercooled liquid glycerol 21 have found that its relaxation spectra is more appropriately described by the H-N equation or by a nonexponential relaxation function, [17][18][19][20] and not by the Davidson-Cole relaxation function. 16 In view of the fact that the dielectric data on supercooled liquid glycerol had led originally to the discovery of a new relaxation function, it may be worthwhile to re-examine the new data in order to determine whether or not its relatively high dc conductivity and the consequent interfacial polarization ͑which can be substantial when the surface to volume ratio of the liquid is large͒ has not contributed significantly to the low-frequency wing of the spectra.…”

Section: A the Spectral Shape And The Effects Of The Solventmentioning

confidence: 73%

“…The latter relationship is a combination of the Cole-Cole relaxation 14,15 and Davidson-Cole relaxation 16 functions. In recent studies, [17][18][19][20][21] of dielectric relaxation in supercooled liquids, the dielectric spectra of glycerol, which was originally found to have an asymmetric shape and had led to the formalism of the Davidson-Cole relaxation function, 16 have been described in terms of the stretched exponential, and H-N ͑Ref. 13͒ equations.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Molecular dynamics of iso-amyl bromide by dielectric spectroscopy, and the effects of a nonpolar solvent, 2-methylpentane, on the spectral features

Kalinovskaya

Vij

1999

The Journal of Chemical Physics

View full text Add to dashboard Cite

To gain insight into the effects of the weakening of the electrostatic interactions on molecular dynamics when polar molecules are dissolved in a nonpolar solvent, the dielectric polarization and relaxation behaviors of iso-amylbromide and its 50 mol % solution in 2-methylpentane have been studied in detail over the frequency range, 1 mHz-1 MHz, and a temperature range approaching their liquid to glass transition. Features of the ͑i͒ ␣-relaxation spectrum, ͑ii͒ the Johari-Goldstein relaxation process in the liquid state at low temperatures, with an asymmetric spectral shape, and ͑iii͒ the temperature dependence of the relaxation dynamics have been determined and the effects of weakening of the electrostatic interaction on these features examined. The high-frequency wing of the loss spectrum of the ␣-relaxation is proportional to Ϫ␤ . The dynamics of its ␣-relaxation follows the Arrhenius equation initially at high temperatures and thereafter the Vogel-FulcherTamman equation. Alternative equations for the change in the relaxation rate have been discussed. A decrease in the dipole-dipole interaction and reduction in the internal field in a solution with a nonpolar solvent leads to a remarkable change in the shape of the relaxation spectra at high frequencies such that the dielectric loss for the ␣-relaxation becomes proportional to Ϫ␣␤ , with ␣, ␤Ͻ1. The relaxation spectra of iso-amyl bromide dissolved in 2-methylpentane follows the H-N function and therefore behaves similar to a polymer, whereas for pure iso-amyl bromide follows the Davidson-Cole behavior.

show abstract

Section: A the Spectral Shape And The Effects Of The Solventmentioning

confidence: 73%

Section: Introductionmentioning

confidence: 99%

Molecular dynamics of iso-amyl bromide by dielectric spectroscopy, and the effects of a nonpolar solvent, 2-methylpentane, on the spectral features

Kalinovskaya

Vij

1999

The Journal of Chemical Physics

View full text Add to dashboard Cite

show abstract

“…16) to calculate the static dielectric constant, for the force fields showing a better performance in the prediction of the dielectric spectrum in every case (water SPC, ethanol TraPPE.UA, ethylene glycol OPLS, propylene glycol GAFF, glycerol OPLS and MEA OPLS). Black circles represent experimental values obtained from different sources for the following systems: water [9.12], ethanol [16.18, 97], ethylene glycol [98], propylene glycol [99], glycerol [95,96,100,101] 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 …”

Section: Discussionmentioning

confidence: 99%

Molecular dynamics simulations for the prediction of the dielectric spectra of alcohols, glycols and monoethanolamine

Cardona

Fartaria

Sweatman

et al. 2015

Molecular Simulation

View full text Add to dashboard Cite

This version is available at https://strathprints.strath.ac.uk/54062/ Strathprints is designed to allow users to access the research output of the University of Strathclyde. Unless otherwise explicitly stated on the manuscript, Copyright © and Moral Rights for the papers on this site are retained by the individual authors and/or other copyright owners. Please check the manuscript for details of any other licences that may have been applied. You may not engage in further distribution of the material for any profitmaking activities or any commercial gain. You may freely distribute both the url (https://strathprints.strath.ac.uk/) and the content of this paper for research or private study, educational, or not-for-profit purposes without prior permission or charge.Any correspondence concerning this service should be sent to the The response of molecular systems to electromagnetic radiation in the microwave region (0.3-300 GHz) has been principally studied experimentally, using broadband dielectric spectroscopy. However, relaxation times corresponding to reorganisation of molecular dipoles due to their interaction with electromagnetic radiation at microwave frequencies are within the scope of modern molecular simulations. In this work, fluctuations of the total dipole moment of a molecular system, obtained through molecular dynamics simulations, are used to determine the dielectric spectra of water, a series of alcohols and glycols, and monoethanolamine. Although the force fields employed in this study have principally been developed to describe thermodynamic properties, most them give fairly good predictions of this dynamical property for these systems. However, the inaccuracy of some models and the long simulation times required for the accurate estimation of the static dielectric constant can sometimes be problematic. We show that the use of the experimental value for the static dielectric constant in the calculations, instead of the one predicted by the different models, yields satisfactory results for the dielectric spectra, and hence the heat absorbed from microwaves, avoiding the need for extraordinarily long simulations or re-calibration of molecular models.

show abstract

“…The plot follows the equation, ␥Ϸa(TϪT 0 ), with aϭ0.0179 and T 0 ϭ78.1 K. This in turn will lead to the VFT dependence of the dielectric relaxation time as suggested by Nagel and Dixon. 29 Lunkenheimer et al 30 have found a similar behavior of the stretched exponent with temperature for glycerol, though they did not show any fitting of the data. It may be remarked that T 0 agrees with that using the mode-coupling theory better than the VFT, however this need to be investigated in detail in future.…”

Section: ͑17͒mentioning

confidence: 93%

Nonexponential dielectric relaxation dynamics in supercooled liquid and glassy states of isoamyl bromide and 2-methylpentane mixtures

Kalinovskaya

Vij

2001

The Journal of Chemical Physics

View full text Add to dashboard Cite

The dielectric spectra of mixtures of the polar solute isoamyl bromide in 2-methylpentane have been investigated in the frequency range 1 mHz to 1 MHz and in the temperature range approaching the glass transition temperature. The results obtained from the spectra are compared with those obtained recently ͓J. Chem. Phys. 111, 10979 ͑1999͔͒ on pure isoamyl bromide. It is found that on increasing dilution with the nonpolar solvent, the width of the curves of the dielectric spectra increase significantly, and this is reflected in the increase in the nonexponential nature of the relaxation dynamics. This is found to be a consequence of the decrease in the cooperativity of the relaxation dynamics and or an increase in the heterogeneity of the solution. The data are found to fit the Havriliak-Negami equation extremely well. The data at low and high frequencies also fits the ''universal law,'' since the latter is a low and high frequencies limiting case of the HavriliakNegami equation. The scaling parameters of this law are calculated for the 25 mol % solution of isoamyl bromide in 2-methylpentane, and these are shown to experimentally relate to the H-N parameters. The stretched exponential parameter, ␥, is estimated as a function of the temperature and is shown to follow the equation ␥Ϸa(TϪT 0 ). Vogel-Fulcher-Tammann equation fits the data of the relaxation peak frequency as a function of the inverse of absolute temperature for the various mixtures quite well, this being possibly a consequence of the temperature dependence of the stretched exponential parameter. The predictions from the mode coupling theory and those by Bertrand and Souletie are verified with the exception that the exponent is found to be much greater than predicted by these theories. The relative predominance of the Johari-Goldstein process in isoamyl bromide increases initially with dilution with 2-methylpentane and then disappears as the number density of the independent relaxors increases with further dilution.

show abstract

High-frequency dielectric spectroscopy on glycerol

Cited by 102 publications

References 17 publications

Molecular dynamics of iso-amyl bromide by dielectric spectroscopy, and the effects of a nonpolar solvent, 2-methylpentane, on the spectral features

Molecular dynamics of iso-amyl bromide by dielectric spectroscopy, and the effects of a nonpolar solvent, 2-methylpentane, on the spectral features

Molecular dynamics simulations for the prediction of the dielectric spectra of alcohols, glycols and monoethanolamine

Nonexponential dielectric relaxation dynamics in supercooled liquid and glassy states of isoamyl bromide and 2-methylpentane mixtures

Contact Info

Product

Resources

About