Dielectric spectroscopy on aqueous electrolytic solutions

In this work, detailed dielectric measurements are presented on aqueous electrolytic solutions of NaCl and KCl in a broad frequency range, typical for modern telecommunication techniques. The complex dielectric permittivity or equivalently the complex conductivity are systematically studied as function of frequency (100 MHz-40 GHz), temperature (10-60 degrees C) and molar concentration (0.001-1 mol/l). By a detailed analysis of the dielectric results using an asymmetrically broadened Cole-Davidson distribution of relaxation times, in addition to dc conductivity, the dielectric response as function of frequency, temperature, and molar concentration was fully parameterized by a total of 13 parameters. This model ansatz and the 13 parameters include an enormous predictive power, allowing a reasonable estimation of the dielectric constant, loss, and the conductivity for any set of external variables frequency, temperature and concentration. The proposed method is not only useful for rather simple electrolytic solutions, but also for cell suspensions and biological matter, if additional processes, especially at low frequencies, are adequately taken into account.