Parts Of Complex Dielectric Constant Research Articles

Dielectric relaxation of DNA solutions. II

AbstractReal and imaganiry parts of complex dielectric constant of dilute solutions of DNA in 10−3M NaCl with molecular weight ranging from 0.4 × 106 to 4 × 106 were measured at frequencies from 0.2 Hz to 30 kHz. Dielectric increments Δε were obtained from Cole‐Cole plots and relaxation times τD from the loss maximum frequency. The τD of all samples agrees well with twice of the maximum viscoelastic relexation time in the Zimm theory, indicating that the low‐frequency dielectric relaxiation should be ascribed to be the rotation of DNA. The rms dipole moment, which was obtained from Δε, agree well with that calculated from the counterion fluctuation theory. The dielectric increment was found to be greatly depressed in MgCl2, which is resonably interpreted in terms of a strong binding of Mg++ ions with DNA.