BRILLOUIN-SCATTERING STUDY OF GLASS-FORMING PROPYLENE-GLYCOL

Brillouin scattering of hypersonic sound waves by fragile glass-formin g propylene glycol has been studied using a (3+3)-pass vernier tandem Fabry-Perot interferometer at temperatures between 364 K and 140 K. Th e velocity dispersion has been analyzed using the Cole-Davidson model (beta(CD) = 0.45) The relaxation time was found to obey the Arrhenius law, and we have obtained Delta E = 0.28 eV and tau(0) = 1.26 x 10(-15 ) s. The relaxation strength (or the Debye-Waller factor in the mode c oupling theory (MCT)) was found to obey the (T-c - T)(1/2) law below T -c = 314 K, as predicted by the MCT. However the crossover temperature T-c was much higher than our previous result of T-c = 227 +/- 5 K whi ch was obtained from the broadband susceptibility spectra.