High-temperature dynamics in glass-forming liquids

The light scattering spectra of several recently investigated glass-forming systems are reanalyzed. The analysis shows that for both fragile and nonfragile glass-forming liquids, there is some general scenario for the dynamics at high temperatures that seems to follow the qualitative scenario suggested by the mode-coupling theory (MCT) of the liquid-glass transition. However, significant quantitative deviations from MCT predictions occur. They are small for fragile and large for nonfragile systems. Moreover, from the analysis a dynamic crossover temperature clearly appears as a universal feature and in all cases it is close to the critical temperature reported within standard MCT analyses.