Double relaxation phenomena of di-substituted benzenes and anilines in non-polar aprotic solvents under high frequency electric field

• Published in: Indian journal of pure & applied physics 2002-11, Vol.40 (11), p.801-815
• Main Authors: Dutta, K, Karmakar, A, Dutta, L, Sit, S K, Acharyya, S
• Format: Article
• Language: English
• ISSN: 0019-5596

They are, however, related with the measured relative permittivities. Values of *tj are calculated from the ratio of the individual slopes of the variations of *yij'' and *yij' with wi at wjRT0, assuming single Debye-like 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 *t1 and *t2 can, however, be obtained-from Frohlich's theoretical formulations of *yij'/*yoij and *yij''/*yoij and compared with those from the experimentally measured values of (*yij'/*yoij)wjRT0 and (*yij''/*yoij)wjRT0. The latter measured values are employed to get symmetric distribution parameter *g to yield symmetric relaxation time *ts. The curve of (1/*q) log(cos *q) against *q in degrees together with the values of (*yij'/*yoij)wjRT0 and (*yij''/*yoij)wjRT0 experimentally obtained, gives the asymmetric distribution parameter *d to get the characteristic relaxation time *tcs. All these findings ultimately establish the different types of relaxation behaviour for such complex molecules. The dipole moments *m*I and *m2 for the flexible part and the whole molecule are ascertained from *t1 and *t2 and the linear coefficients *b1 of *yij' versus wj and *b2 of *sij versus wj curves respectively, where *sij, is the hf conductivity. The values of *m are finally compared with the reported *m's and *mtheo'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 *m and *mtheo can, however, be interpreted by the inductive, mesomeric and electromeric effects of the polar groups of the parent molecules.