On the Dielectric Dispersion of Polyelectrolytes, with Application to DNA

摘要

It has been reported in the literature that dielectric relaxation times measured in a DNA solution are orders of magnitude too large to be consistent with a Maxwellmdash;Wagner mechanism. It has thus been concluded that the dielectric dispersion is associated with the rotation of molecules. It is shown in this paper that this conclusion is based on the use of an expression for the relaxation time which is not applicable to the case of highly elongated molecules. An expression is given which is appropriate to the case of a Maxwellmdash;Wagner mechanism for highly elongated polyelectrolyte molecules. It yields a value for the relaxation time which compares well with the experimental results reported in literature.Results of experiments on the anisotropy of the relaxation times in a flowing solution of DNA are reported. These results indicate clearly that the dielectric dispersion is indeed due to a Maxwellmdash;Wagner mechanism.