Low-temperature specific heat and glassy dynamics of a polymorphic molecular solid

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Abstract
The low-frequency dynamics of different solid phases of ethanol (fully ordered crystal, orientational glass, and true structural glass) is investigated by measurements of low-temperature specific heat as well as determination of the vibrational densities of states by inelastic neutron scattering. Such polymorphism provides a unique benchmark to study the relative importance of different kinds of disorder on glass-dynamics properties. The measurements are carried out both for hydrogenous and fully-deuterated samples. Large isotopic effects are found for the excess contributions (i.e., non-Debye) to the specific heat of the disordered solids, which have clear correlates in the low-frequency spectra.