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|Title:||Double relaxation phenomena of di-substituted benzenes and anilines in non-polar aprotic solvents under high frequency electric field|
Dutta, (Mrs) L
Sit, S K
|Abstract:||The derived linear equation (χOij-χij’) / χij’ = ω(τ1+ τ2) χij’’/ χij’ -ω2τ1τ2 for different weight fractions wi of di-substituted benzenes and anilines (j) in aprotic and non-polar solvents. C6H6 and CCl4 under 9.945 GHz electric field are obtained from the available measured dielectric relative permittivities at 35°C. The double relaxation times τ1 and τ2 of the flexible part and the whole molecule are estimated from the slope and intercept of the above equation. χij’ and χij’’ are the real and imaginary parts of the high frequency complex orientational dielectric susceptibility χij*and χOij is the low frequency dielectric susceptibility, which is real. They are, however, related with the measured relative permittivities. Values of τi are calculated from the ratio of the individual slopes of the variation of χij’’ and χij’ with wi at wj→0, assuming single Debyelike dispersion and. compared with Murthy et al. [Indian J Phys, 63B (1989) 491] and Gopalakrishna [Trans Faraday Soc,53 (1957) 767. The weighted contributions c1 and c2 towards dielectric relaxations for τ1 and τ2 can, however, be obtained from Frohlich's theoretical formulations of χij’ / χOij and χij’’/ χ(Oij and compared with those from the experimentaly measured values of (χij’ / χOij)wj→0 and (χij’’/ χOij) wj→0 . The latter measured values are employed to get symmetric distribution parameter γ to yield symmetric relaxation time τs. The curve of (1/) log(cos ) against in degrees together with the values of(χij’ / χOij)wj→0 and (χij’’/ χ(Oij) wj→0 experimentally obtained, gives the asymmetric distribution parameter δ to get the characteristic relaxation time τcs. All these findings ultimately establish the different types of relaxation behaviour for such complex molecules. The dipole moments μ1 and μ2 for the flexible part and the whole molecule are ascertained from τ1 and τ2 and the linear coefficients β1 of χij’ versus wj and β2 of σij versus wj curves respectively, where σij is the hf conductivity. The values of μ are finally compared with the reported μ's and μtheo's derived from available bond angles and bond moments of the substituted polar groups of di-substituted anilines to conclude that a part of the molecule is rotating while the whole molecular rotation occurs for di -substituted benzenes. The slight disagreement between measured values of μ and μtheo can however, be interpreted by the inductive, mesomeric and electromeric effects of the polar groups of the parent molecules.|
|ISSN:||0975-1041 (Online); 0019-5596 (Print)|
|Appears in Collections:||IJPAP Vol.40(11) [November 2002]|
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