Merging of α and slow β relaxation in supercooled liquids -: art. no. 031503

Dielectric relaxation spectroscopy (1 Hz - 20 GHz) has been performed on supercooled glass-formers from the temperature of glass transition (T-g) up to that of melting. Precise measurements particularly in the frequencies of MHz order have revealed that the temperature dependences of secondary beta relaxation times in well above T-g deviate from the Arrhenius relation below T-g: the beta process does not merge with the alpha process around the dynamical crossover temperature in contradiction to previously speculated extrapolations.