Spectral Shape of the α-Process in Supercooled Liquids Revisited

The scaling form presented by Nagel and coworkers for the α-process in supercooled liquids is re-examinated in the light of new dielectric relaxation data. Several data sets are compared in order to check quantitative relationships implied by the scaling and to examine the reliability of dielectric measurements. The analysis shows that no master curve can be obtained by the procedure suggested. Furthermore, we find that the scaling may obscure peculiarities in the dielectric response, e.g., for the glass formers salol and tricresyl phosphate additional relaxation processes are suppressed. We conclude that the spectral shape of the α-process remains an open question.