Dielectric relaxation phenomena of rigid polar liquid molecules under giga hertz electric field

• Published in: Pramāṇa 2001-10, Vol.57 (4), p.775-793
• Main Authors: Dutta, K, Sit, SK, Acharyya, S
• Format: Article
• Language: English
• Subjects: Aliphatic compounds; Benzene; Chloral; Dielectric relaxation; Dipole moments; Electric fields; Heptanes; Hexanes; Skewed distributions; Solvents
• ISSN: 0304-4289; 0973-7111
• DOI: 10.1007/s12043-001-0028-6

The dielectric relaxation phenomena of rigid polar liquid molecules chloral and ethyltrichloroacetate (j) in benzene, n-hexane and n-heptane (i) under 4.2, 9.8 and 24.6 GHz electric fields at 30°C are studied to show the possible existence of double relaxation times τ2 and τ1 for rotations of the whole and the flexible parts of molecules. The probability of showing double relaxation is more in aliphatic solvents indicating their nonrigidity. The symmetric and asymmetric distribution parameters γ and δ are obtained from Xij′/X0ij and Xij″/X0ij and wj→0 where Xij′ and Xij″ are real and imaginary parts of the complex orientational susceptibility Xi* and X0ij is the low frequency susceptibility which is real. Xij’s are involved with the measured dielectric relative permittivities εij′, εin″, ε0ij and ε∞ij of solutions. The theoretical weighted contributions c1 and c2 towards dielectric dispersions by Fröhlich’s method are compared with the experimental ones obtained from the graphical variation of Xij′/X0ij and Xij″/X0ij with weight fractions wj’s at wj → 0. The measured dipole moments μ2 and μ1 of the whole and the flexible part of a polar molecule in terms of the linear coefficients β’s of Xij′’s with wj’s and the estimated τ2 and τ1 reveal their associations with aliphatic solvents. The theoretical dipole moments μtheo’s from the available bond angles and bond moments of the substituent polar groups of the molecules with the estimated μ’s suggest the mesomeric, inductive and electromeric effects in them under GHz electric field.