The role of nucleation in vitrification of supercooled liquids.

Low-frequency Raman and differential scanning calorimetry (DSC) investigations were carried out during a structural transformation of supercooled liquid salol (phenyl salicylate) in a wide temperature range. DSC experiments indicate that in the supercooled liquid salol at temperature ~40 K above the glass transition temperature metastable nuclei start to form. During subsequent cooling the nuclei become an important element of the glass structure, and thereby are considered as a measure of the intermediate range order in this glass. It was shown that the crystalline structure of the metastable nuclei differ from that of the stable nuclei. Low-frequency Raman spectra of the glassy salol show a broad band in the spectral range from 14.5 to 17.2 cm(-1); the so called 'Boson peak', which can be interpreted in terms of its relationship to the formation of structured clusters, with typical sizes in the nanometer range (critical radii).