Temperature dependence of the dielectric relaxation of liquid dimethyl- and diethylsulfoxides

Dielectric loss spectra of pure liquid dimethylsulfoxide (DMSO) and diethylsulfoxide, (DESO) have been measured from 0.3 to 72 GHz at 40 and 60 degreesC. Considering also a previous result for 20 degreesC it turns out that in the whole temperature range the DMSO spectrum is practically of Debye type whereas the DESO spectrum is slightly broadened towards the high frequency side, formally to be described by a Cole-Davidson function. Besides spectral parameters, also activation energies as calculated from relaxation times and Kirkwood correlation factors are reported. (C) 2003 Elsevier B.V. All rights reserved.