Quasi-linear least squares and computer code for numerical evaluation of relaxation time distribution from broadband dielectric spectra

Abstract

We present a new fitting procedure and computer code for numerical evaluation of dielec. relaxation time distribution functions. The technique is based on linear least squares minimization and aims primarily at the anal. of compd. exptl. spectra of complex dielec. permittivity. It is fast, robust, and easy to use. No prior knowledge about the no. of relaxation modes, their characteristic times, relaxation strengths, or the functional form of the underlying relaxation time distribution function is required, the procedure dets. these parameters instead. The method is tested by both synthetic spectra with well-defined parameters of dielec. relaxation and exptl. wide-band dielec. spectra of different types. We believe that this new fitting instrument, which allows an unbiased approach to the formal description of dielec. spectra, may be of interest in many areas of dielec. spectroscopy.