We have measured the dielectric susceptibility of several glass-forming liquids over 13 decades of frequency. The primary relaxation for all the liquids, over the entire frequency and temperature range studied, can be collapsed onto a single scaling curve with only two parameters, peak position and width. This curve is different from any of the theoretical forms suggested in the literature. The relaxation evolves smoothly from Debye behavior at high temperature.

• Received 7 May 1990

DOI:https://doi.org/10.1103/PhysRevLett.65.1108