Temperature and Pressure Scaling of theαRelaxation Process in Fragile Glass Formers: A Dynamic Light Scattering Study

The dynamics of two fragile glass forming liquids was studied as a function of temperature and pressure using dynamic light scattering. On the basis of measured data we evaluated the pressure and temperature scaling of the $\alpha$ relaxation. All the isotherms can be superimposed and form a master curve when the reduced relaxation times are plotted versus reduced pressure. The Kohlrausch-Williams-Watts stretching parameter ${\beta }_{\mathrm{KWW}}$ is increasing with increasing temperature and decreasing pressure and plotted versus $\log 〈{\tau }_{\mathrm{KWW}}〉$ follows a master curve at all temperatures and pressures studied.