Raman scattering study of glass crystallization kinetics.

Laser induced glass-crystalline transition is studied by light scattering. Three significant effects are observed depending on the incident laser energy density: i) Spectral band narrowing indicating cluster enlargement constitutes a precursor effect, ii) an intensity increase effect indicates a rapid rise of the density of clusters attaining microcrystallite size and iii) a dynamical reversal effect indicative of glass-crystalline instability. Cluster volume growth and crystallization appear as separate but related threshold phenomena.