Susceptibility functions for disordered materials: the full width at half maximum for different frequency and time representations

We here propose relations that provide a convenient way to obtain, from cur ve-fit parameters, the full width at half maximum (FWHM), which is one of t he fundamental parameters in the scaling procedure for relaxations in disor dered materials proposed by Dixon et al. We derive an analytical expression for the FWHM for symmetric loss peaks using a newly proposed response func tion. Since the response function contains e.g. the Cole-Cole and the Fouss -Kirkwood expressions as special cases, exact analytical expressions of the FWHM is also obtained for these functions. For asymmetric loss peaks, appr oximations are introduced and we show that the errors for the obtained func tions are less than 6%. Furthermore, we propose an approximate relation bet ween the stretching parameter, beta, of the Kohlrausch-Williams-Watts funct ion and the FWHM. (C) 2001 Elsevier Science B.V. All rights reserved.