ANHARMONIC DYNAMICS IN CRYSTALLINE, GLASSY, AND SUPERCOOLED-LIQUID GLYCEROL - A CASE-STUDY ON THE ONSET OF RELAXATIONAL BEHAVIOR

The temperature dependence of the spectral distributions of the glass, crystalline, and supercooled-liquid phases of glycerol is investigate d by means of neutron inelastic scattering. The importance of anharmon ic effects is quantified by the temperature dependence of reduced spec tral frequency moments. The onset of relaxational (i.e., stochastic, z ero-frequency) motions in the supercooled liquid state is monitored by neutron quasielastic scattering. A substantial deviation of the obser ved linewidths from the hydrodynamic prescription is observed and is i nterpreted at a microscopic level, by comparison with the crystalline phase.