STRUCTURAL FLUCTUATIONS IN GLASS-FORMING LIQUIDS - MOSSBAUER-SPECTROSCOPY ON IRON IN GLYCEROL

Mossbauer absorption spectra of Fe-57(2+) dissolved in a glycerol-water mixture have been measured over a wide temperature range (80-275 K). In the supercooled liquid state the shapes of the spectra depend strongly on temperature. The Mossbauer spectra can be fit with jump diffusion with a Cole-Davidson distribution of fluctuation times. The results are in agreement with those obtained from dielectric and ultrasonic volume relaxations, proving that the alpha-relaxation of viscous liquids is responsible for the line broadening of the spectra. From the temperature dependence of the integrated area of the Mossbauer spectrum a second dynamic process is inferred. Its activation energy of 31.4 kJ/mol is typical for the beta-relaxation.