S N Helambe
Articles written in Pramana – Journal of Physics
Volume 44 Issue 5 May 1995 pp 405-410
Time domain reflectometry method has been used in the frequency range of 10 MHz to 10 GHz to determine dielectric properties of aqueous solutions of acetonitrile in temperature range of 0°C to 40°C. The calibration method based on the least squares fit method has been used. The excess permittivity, activation energy, Kirkwood correlation factor and activation energy of acetonitrile-water system have also been determined. The dielectric data show that acetonitrile molecules interact such that the dipoles have a tendency to remain antiparallel.
Volume 45 Issue 1 July 1995 pp 19-24
Dielectric properties of nitriles have been studied using time domain reflectometry in the frequency range of 10 MHz to 10 GHz over the temperature range of 0°C to 45°C. The calculated dielectric relaxation parameters are compared with values for the corresponding n-alcohols. The dielectric behaviour in n-nitrile systems is quite different from the corresponding behaviour in n-alcohols. The dipoles in n-nitrile systems show a tendency to remain antiparallel, unlike in alcohol systems. The activation energy decreases with the increase of molecular size, whereas in hydrogen bonded liquid it increases.
Volume 46 Issue 2 February 1996 pp 91-98
The complex permittivity, static dielectric constant and relaxation time for tetrahydrofuran-water and acetone-water mixtures have been determined at 0°, 10°, 25° and 35°C using time domain reflectometry technique (TDR). The behaviour of relaxation time of the mixture shows a maxima for the mixture with 30% of water by volume. This suggests that the tendency to form cluster between water and solute molecule is maximum for this mixture. The excess permittivity for both tetrahydrofuran-water mixture and acetone-water mixtures, are found to be negative. The Kirkwood correlation factor has been determined at various concentrations of water. Static dielectric constant for the mixtures have been fitted well with the modified Bruggeman model. The values of the Bruggeman parameter
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