The dielectric relaxation of some diols in p-dioxane solution

1978 ◽  
Vol 56 (3) ◽  
pp. 352-354 ◽  
Author(s):  
J. Crossley
Keyword(s):  
Dielectric Constant ◽  
Dielectric Relaxation ◽  
Relaxation Process ◽  
Alkyl Group ◽  
Relaxation Times ◽  
Dielectric Dispersion ◽  
Dioxane Solution ◽  
Microwave Frequencies ◽  
Dielectric Absorption ◽  
Dielectric Constant And Loss

Dielectric constant and loss data at up to nine microwave frequencies have been obtained for 1-butanol, 1,4-butanediol, 1,7-heptanediol, 1,8-octanediol, 1,10-decanediol, and 1,12-do-decanediol at 25 °C, and for 1,6-hexanediol at 15, 25, 40, and 55 °C, in p-dioxane. In each case the dielectric dispersion is adequately described by a Cole-Cole distribution. The relaxation times for the diols are almost independent of the length of the alkyl group. An intramolecular relaxation process appears to be primarily responsible for the dielectric absorption.

Dielectric studies. Part XXV. Methoxy group rotation in anisole and three para-substituted anisoles

1969 ◽  
Vol 47 (24) ◽  
pp. 4645-4650 ◽  
Author(s):  
D. B. Farmer ◽  
S. Walker
Keyword(s):  
Relaxation Process ◽  
Methoxy Group ◽  
Relaxation Times ◽  
Pure Liquid ◽  
Relaxation Processes ◽  
Molecular Relaxation ◽  
Microwave Frequencies ◽  
Dielectric Absorption ◽  
Weight Factors ◽  
Group Rotation

The dielectric absorption at several microwave frequencies of anisole, p-methylanisole, and p-bromoanisole in the solvent p-xylene, and p-dimethoxybenzene in the solvent cyclohexane has been investigated at 4 to 6 temperatures. Anisole, p-methylanisole, and p-dimethoxybenzene were all found to relax mainly by methoxy group rotation, whereas the relaxation process in p-bromoanisole was very largely molecular relaxation. In the literature, considerable divergence exists for the analyses of the dielectric data of anisole and substituted anisoles into contributions from two relaxation times and the magnitude of the weight factors governing each relaxation process. Such divergencies have been explored and justifiable analyses established for these systems where the weight factors governing the relaxation processes are shown to be roughly of the same order as those estimated from group moment data. The weight factor for molecular relaxation in the pure liquid appears considerably greater than that for a dilute solution of it in a non-polar solvent.

Dielectric Relaxation of Bromoalkanes in Cyclohexane Solution

1972 ◽  
Vol 50 (13) ◽  
pp. 2031-2034 ◽  
Author(s):  
Sing Pin Tay ◽  
John Crossley
Keyword(s):  
Dielectric Constant ◽  
Dielectric Relaxation ◽  
Dipole Moments ◽  
Relaxation Times ◽  
Dielectric Constant And Loss ◽  
Distribution Parameters

Mean relaxation times, Cole–Cole distribution parameters and apparent dipole moments, obtained from dielectric constant and loss measurements at 2 MHz and 1.5, 2.0, 2.5, 9.3, 16, 24, 35, 70, and 145 GHz, are reported for 1-, 2-, and 4-bromooctane, 1-bromodecane, 1-bromododecane, 1-bromohexadecane, 1-bromooctadecane, and 1,10-dibromodecane in cyclohexane solution at 25 °C.

A Cavity Perturbation Technique for Measuring Complex Dielectric Permittivities of Liquids at Microwave Frequencies

1974 ◽  
Vol 52 (23) ◽  
pp. 2365-2369 ◽  
Author(s):  
Abhai Mansingh ◽  
D. B. McLay ◽  
K. O. Lim
Keyword(s):  
Dielectric Constant ◽  
Benzene Solution ◽  
Dipole Moments ◽  
Perturbation Technique ◽  
Relaxation Times ◽  
Microwave Frequencies ◽  
Dielectric Constant And Loss ◽  
End Caps ◽  
Good Agreement

A microwave technique for measuring the complex dielectric permittivity of liquids by using a cylindrical cavity oscillating in the TM010 mode is described. The liquid is placed in a cylindrical teflon cell and the dielectric constant and loss of the liquid are evaluated by measuring accurately the changes in the resonant frequency and Q of the cavity for the composite sample and for the teflon alone. This technique has been used to measure the dielectric constant and loss at 2.4 GHz of some pure liquids and solutions in benzene of ortho and meta isomers of difluoro-, dichloro-, dibromo-, and diiodo-benzene. The measured values for the pure liquids are in good agreement with the literature values. The dielectric relaxation times and dipole moments of the dihalobenzenes in benzene solution evaluated by assuming a simple Debye type dispersion show good agreement with the earlier calculated values derived from Cole–Cole plots based on measurements at several microwave frequencies. This technique, by virtue of the use of a teflon cell and of gold plated end caps, allows the determination of the dielectric properties of corrosive liquids at microwave frequencies and another advantage is that very small liquid samples are required.

Dielectric Relaxation Studies of Silver Nanoparticles dispersed Liquid Crystal

2015 ◽  
Vol 8 (3) ◽  
pp. 2176-2188 ◽  
Author(s):  
Keisham Nanao Singh
Keyword(s):  
Activation Energy ◽  
Silver Nanoparticles ◽  
Liquid Crystal ◽  
Dielectric Relaxation ◽  
Relaxation Process ◽  
Relaxation Times ◽  
Low Frequency ◽  
Bulk Liquid ◽  
Molecular Rearrangement ◽  
Relaxation Studies

This article reports on the Dielectric Relaxation Studies of two Liquid Crystalline compounds - 7O.4 and 7O.6 - doped with dodecanethiol capped Silver Nanoparticles. The liquid crystal molecules are aligned homeotropically using CTAB. The low frequency relaxation process occurring above 1 MHz is fitted to Cole-Cole formula using the software Dielectric Spectra fit. The effect of the Silver Nanoparticles on the molecular dipole dynamics are discussed in terms of the fitted relaxation times, Cole-Cole distribution parameter and activation energy. The study indicate a local molecular rearrangement of the liquid crystal molecules without affecting the order of the bulk liquid crystal molecules but these local molecules surrounding the Silver Nanoparticles do not contribute to the relaxation process in the studied frequency range. The observed effect on activation energy suggests a change in interaction between the nanoparticles/liquid crystal molecules.

Determination of dielectric constant and loss of high-K thin films in the microwave frequencies

Measurement ◽  
2010 ◽  
Vol 43 (4) ◽  
pp. 556-562 ◽  
Author(s):  
K. Sudheendran ◽  
D. Pamu ◽  
M. Ghanashyam Krishna ◽  
K.C. James Raju
Keyword(s):  
Thin Films ◽  
Dielectric Constant ◽  
Microwave Frequencies ◽  
Dielectric Constant And Loss ◽  
High K

Dielectric studies. Part XX. Molecular relaxation of some heterocyclic amines in dilute solution

1968 ◽  
Vol 46 (14) ◽  
pp. 2369-2372 ◽  
Author(s):  
J. Crossley ◽  
S. Walker
Keyword(s):  
Relaxation Time ◽  
Dipole Moments ◽  
Relaxation Times ◽  
Lone Pair ◽  
Intermolecular Forces ◽  
Dilute Solution ◽  
Microwave Frequencies ◽  
Heterocyclic Molecules ◽  
Dielectric Constant And Loss ◽  
The Difference

Dielectric constant and loss data have been obtained at microwave frequencies for acridine, 4-methyl-pyridine, phthalazine, quinoline, and isoquinoline in both cyclohexane and p-xylene solution. The data have been used to calculate relaxation times and apparent dipole moments. For phthalazine, quinoline, and isoquinoline in cyclohexane at 50 °C the distribution coefficient is zero and their relaxation times are very similar. Although the axes about which these three molecules may relax lead to different volumes being swept out, no variation in relaxation behavior has been detected, and each system can be characterized by one relaxation time. The relaxation times for all the heterocyclic molecules except quinoline and acridine in p-xylene are appreciably longer than in cyclohexane. Relaxation time values appear a sensitive means of detecting the weak molecular interaction between the amine and the p-xylene. The difference in behavior between the quinoline and acridine as opposed to isoquinoline could be attributed to a more appreciable steric effect in the former two, hindering the approach of the π-electrons of the p-xylene molecules to the hybridized lone pair on the nitrogen atom. No interaction is, in fact, detectable in the case of quinoline and acridine. The importance of allowing for weak intermolecular forces, even in dilute solution, when relaxation values are being anticipated, is emphasized.

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