REORIENTATIONAL RELAXATION TIME AT THE ONSET OF INTERMOLECULAR COOPERATIVITY

摘要

For three liquids, salol, propylene carbonate, and o-terphenyl, we show that the relaxation time or the viscosity at the onset of Arrhenius behavior is a material constant. Thus, while the temperature of this transition can be caltered by the application of pressure, the time scale of the dynamics retains a haracteristic, pressure-independent value. Since the onset of an Arrhenius mperature-dependence and the related Debye relaxation behavior signify the loss of intermolecular constraints on the dynamics, our result indicates that intermolecular cooperativity effects are governed by the time scale for structural relaxation.