LOW-TEMPERATURE SPECIFIC-HEAT AND GLASSY DYNAMICS OF A POLYMORPHIC MOLECULAR-SOLID

The low-frequency dynamics of different solid phases of ethanol (fully ordered crystal, orientational glass, and tore structural glass) is i nvestigated by measurements of low-temperature specific heat as well a s determination of the vibrational densities of states by inelastic ne utron scattering. Such polymorphism provides a unique benchmark to stu dy the relative importance of different kinds of disorder on glass-dyn amics properties. The measurements are carried out both for hydrogenou s and fully-deuterated samples. Large isotopic effects are found for t he excess contributions (i.e., non-Debye) to the: specific heat of the disordered solids, which have clear correlates in the low-frequency s pectra. [S0163-1829(98)05626-4].