S K Sit
Articles written in Pramana – Journal of Physics
Volume 61 Issue 4 October 2003 pp 759-772 Brief Reports
Relaxation phenomena of polar non-polar liquid mixtures under low and high frequency electric field
Simultaneous calculation of the dipole moment μ_{j} and the relaxation time τ_{j} of a certain number of non-spherical rigid aliphatic polar liquid molecules (j) in non-polar solvents (i) under 9.8 GHz electric field is possible from real ε′_{ij} and imaginary ε″_{ij} parts of the complex relative permittivity ε*_{ij}. The low frequency and infinite frequency permittivities ε_{0ij} and ε_{∞ij} measured by Purohit
Volume 70 Issue 3 March 2008 pp 543-552 Research Articles
Dielectric relaxation of binary polar liquid mixture measured in benzene at 10 GHz frequency
S Sahoo K Dutta S Acharyya S K Sit
The dielectric relaxation times $\tau_{jk}$'s and dipole moments $\mu_{jk}$'s of the binary ($j_{k}$) polar liquid mixture of N,N-dimethyl acetamide (DMA) and acetone (Ac) dissolved in benzene (i) are estimated from the measured real $\sigma_{ijk}^{'}$ and imaginary $\sigma_{ijk}^{''}$ parts of complex high frequency conductivity $\sigma_{ijk}^{*}$ of the solution for different weight fractions $w_{jk}$'s of 0.0, 0.3, 0.5, 0.7 and 1.0 mole fractions $x_{j}$ of Ac and temperatures (25, 30, 35 and 40°C) respectively under 9.88 GHz electric field. $\tau_{jk}$'s are obtained from the ratio of slopes of $\sigma_{ijk}^{''} - w_{jk}$ and $\sigma_{ijk}^{'} - w_{jk}$ curves at $w_{jk} \rightarrow 0$ as well as linear slope of $\sigma_{ijk}^{''} - \sigma_{ijk}^{'}$ curves of the existing method (Murthy
Volume 77 Issue 2 August 2011 pp 395-404
Structural and associational aspects of polar amides (𝑗) like formamide, acetamide, Nmethyl acetamide (NMA), N,N-dimethyl formamide (DMF), N,N-dimethyl acetamide (DMA) and acetanilide dissolved in the nonpolar solvent (𝑖) benzene or 1,4-dioxan have been estimated from the measured static relative permittivity $\varepsilon_{0ij}$ and high-frequency permittivity $\varepsilon_{\infty ij}$ at different weight fractions $w_j$s of polar solute at 35°C under static electric ﬁeld using Debye model of polar liquid molecule. The static dipole moments $\mu_s$s are compared with $\mu_j$s reported from conductivity method and theoretical $\mu_{\text{theo}$s to get exact $\mu_{\text{cal}} \cdot \mu_{\text{theo}$s of the molecules are predicted from the available bond angles and bond moments where difference in electron afﬁnity exists between two adjacent atoms of a polar group due to inductive, mesomeric and electromeric effects in them. Solute–solute molecular association for NMA in benzene and solute–solvent association for other amides are ascertained to arrive at their conformational structures.
Volume 83 Issue 4 October 2014 pp 579-595 Research Articles
Dielectric relaxation of ethanol and 𝑁-methyl acetamide polar mixture in C_{6}H_{6} at 9.90 GHz
Debye relaxation times $(\tau_{jk})$ and dipole moments $(\mu_{jk})$ of binary ($jk$) polar mixtures of ethanol (EtOH) and 𝑁-methyl acetamide (NMA) dissolved in benzene(i) are studied by studying conductivity of solution at 9.90 GHz for different temperatures, different mole fractions ($x_j$) of ethanol and different weight fractions $(w_{jk})$ of the mixtures, respectively. The variation of $\tau_{jk}−x_j$ from linear slope of imaginary ($\sigma''_{ijk}$) against real ($\sigma'_{ijk}$) part of total conductivity ($\sigma^{\ast}_{ijk}$) curve reveals solute–solute (dimer) or solute–solvent (monomer) molecular associations up to $x_j$ = 0.0−0.3 and thereafter, solute–solvent molecular associations. $\tau_{jk}$s from the ratio of slopes of $\sigma''_{ijk}$−w_{jk}$ and $\sigma'_{ijk}$−w_{jk}$ curves exhibit solute–solvent molecular association for all $x_j$s which are consistent with the $\mu_{jk}−x_j$ curves at all temperatures except at 35°C. This signifies the validity of both the proposed methods in estimating 𝜏 and 𝜇. The molecular dynamics of the polar mixture are ascertained from Eyring rate theory. Theoretical dipole moments from bond angles and bond moments ($\mu_{\text{theo}}$) are also calculated to predict associational aspects.
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