Exclusion of DC conductivity effect from dielectric loss spectrum using Kramers–Kronig relations for evaluation of slow dynamics of water molecules

Abstract

In the dielectric spectroscopy of aqueous systems containing ions, the dielectric loss spectrum is affected by the contribution of the direct current (DC) conductivity σ, which sometimes significantly overlaps the dielectric relaxations related to the slow dynamics of water molecules distributing in sub-GHz frequency range. We have demonstrated a practical procedure based on the Kramers–Kronig (KK) relations to exclude the contribution of DC conductivity from the experimentally obtained dielectric spectrum. Examples of the KK transform for the spectrum of ultrapure water and aqueous solution of protein (lysozyme) showed the feasibility of our method.