Anomalies in the scaling of the α-relaxation studied by dielectric spectroscopy

Correlation of temperature dependence of quasielastic-light-scattering intensity and α-relaxation time

“…We compared our experimental results for the intensity of the quasielastic light scattering in propylene glycol with the literature data on the temperature dependence of the ␣-relaxation time obtained by the dielectric measurements. 18,19 The value of T 0 found by fitting the QLS data is in good agreement with that found from the temperature dependence of ␣ (T).…”

“…There are different estimations of T c in propylene glycol. Scaling study of dielectric ␣ relaxation by Schönhals et al 18 predicts T c ϭ251.3 K, while a recent study of the glass transition dynamics by fluorescence measurement of doped chromophores 19 reported T c ϭ211.3 K. We also used the fit of high-temperature data for propylene glycol by the MCT formula ␣ (T)ϰ(TϪT c ) Ϫ␥ to find T c . Our fit of the ␣ (T) data of Ref.…”

“…Taking into account these results, we use the low-temperature value of T 0 found using data between T g and, roughly, 220-240 K. The fit of the literature data 19 for ␣ gives T 0 ϭ110 K. In Ref. 18 it was found that T 0 ϭ117 K. The linear fit of the QLS data for g(T) in the abovementioned temperature interval gives a value of T 0 in good agreement with these predictions ͑Fig. 3͒.…”

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

“…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.…”

“…8,9 The relaxation spectra are currently analyzed [1][2][3][4][5][6][7][8][9] in terms of a set of equations that are approximately equivalent to the variation of the dielectric loss with frequency according to a ''fractional power-law'' at both the low-frequency and high frequency sides of the relaxation peak. These equations are the stretched exponential relaxation function [10][11][12] in the time domain, Havriliak-Negami or H-N equation 13 in the frequency domain.…”