Dynamics of glass-forming liquids at high temperatures: A general scenario

An analysis of light scattering spectra of different glass-forming liquids is presented. It is shown that at high temperatures one finds a scenario for the temperature variations of dynamic spectra at high frequencies which is common for strong and fragile liquids. This scenario breaks down at some crossover temperature T_x. One conclusion is that the difference between strong and fragile glass-forming liquids is the temperature range between T_x and T_g: it is small for fragile and large for strong glass-forming systems.