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.

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.

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.

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.

Temperaturabhängigkeit der statischen Dielektrizitätskonstante und des optischen Brechungsindexes von Flüssigkeiten

1975 ◽  
Vol 30 (3) ◽  
pp. 287-291 ◽  
Author(s):  
I. Gryczyński ◽  
A. Kawski
Keyword(s):  
Dielectric Constant ◽  
Refractive Index ◽  
Dipole Moment ◽  
Dipole Moments ◽  
Mixed Solvents ◽  
Temperature Changes ◽  
Temperature Dependences ◽  
Solvent Shifts ◽  
Pure And Mixed Solvents ◽  
Good Agreement

A variation of the temperature changes the static dielectric constant (ε) and the refractive index (n) of solvents and, in conjunction with the measurement of solvent shifts of absorption and fluorescence maxima, allows the investigation of dipole moment changes of solutes in the excited state. For this purpose, investigations of the temperature dependences of ε and n of some pure and mixed solvents of different polarities have been made. It is found that the excited dipole moments of indole, 1,2-dimethylindole, 2,3-dimethylindole and tryptophan obtained from the shifts of the fluorescence maxima in mixed solvents at high temperatures are in good agreement with those obtained in other ways.

scholarly journals Single-sided NMR for the measurement of the degree of cross-linking and curing

2018 ◽  
Vol 7 (1) ◽  
pp. 21-30 ◽  
Author(s):  
Norbert Halmen ◽  
Christoph Kugler ◽  
Eduard Kraus ◽  
Benjamin Baudrit ◽  
Thomas Hochrein ◽  
...  
Keyword(s):  
Relaxation Times ◽  
Curing Kinetics ◽  
Cross Linking ◽  
Scanning Calorimetry ◽  
First Results ◽  
Non Destructive ◽  
Kinetics Of ◽  
Good Agreement

Abstract. The degree of cross-linking and curing is one of the most important values concerning the quality of cross-linked polyethylene (PE-X) and the functionality of adhesives and resin-based components. Up to now, the measurement of this property has mostly been time-consuming and usually destructive. Within the shown work the feasibility of single-sided nuclear magnetic resonance (NMR) for the non-destructive determination of the degree of cross-linking and curing as process monitoring was investigated. First results indicate the possibility of distinguishing between PE-X samples with different degrees of cross-linking. The homogeneity of the samples and the curing kinetics of adhesives can also be monitored. The measurements show good agreement with reference tests (wet chemical analysis, differential scanning calorimetry, dielectric analysis). Furthermore, the influence of sample temperature on the characteristic relaxation times can be observed.

Appareil pour la mesure de moments dipolaires

1970 ◽  
Vol 48 (11) ◽  
pp. 1698-1702 ◽  
Author(s):  
C. Barbeau ◽  
L. Ricard ◽  
J. Turcotte
Keyword(s):  
Dielectric Constant ◽  
Dipole Moments ◽  
Guggenheim Method

A system is described which enables the determination of dipole moments of magnitude 1.0 D from as little as 10−4 mole of substance. The dielectric constant can be measured with a precision of ± 0.000008 unit. Only one weighing is necessary. A modified Guggenheim method, in which only the values of the dielectric constant are required, is used to calculate the dipole moments.

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