HIGH-TEMPERATURE DYNAMICS IN GLASS-FORMING LIQUIDS

The light scattering spectra of several recently investigated glass-fo rming 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 qualita tive scenario suggested by the mode-coupling theory (MCT) of the liqui d-glass transition. However, significant quantitative deviations from MCT predictions occur. They are small for fragile and large for nonfra gile systems. Moreover, from the analysis a dynamic crossover temperat ure clearly appears as a universal feature and in all cases it is clos e to the critical temperature reported within standard MCT analyses.