Density of vibrational states and light-scattering coupling coefficient in the structural glass and glassy crystal of ethanol

Abstract

The density of vibrational states in the terahertz regime of ethanol in both the structural glass and the glassy crystal has been extracted from low-temperature specific heat data published previously via the Tikhonov regulation method. In addition, low-frequency light-scattering (LS) spectra (boson peak) have been measured for these two phases at low temperature (11 K) applying a tandem Fabry-Pérot interferometer. By comparing the LS data and the density of states, the light-vibration coupling coefficient is extracted. It is shown that the coupling coefficient is essentially the same for both disordered phases, obeying a linear frequency dependence down to 200 GHz.

Vibrational and structural properties of amorphous n-butanol: A complementary Raman spectroscopy and X-ray diffraction study

“…20,21 Also found was a universal linear behavior 22 C(ω) ∝ (ω / ω BP + B) near the boson peak (BP) maximum, with two groups of glasses corresponding to B = 0 and 0.5. In the case of ethanol, it was found 23 that B = 0.5, indicating that χ (ω) is not linearly proportional to G(ω). However, low-frequency dynamics in the fragile molecular glass former triphenyl phosphite 24 by coupled Raman and inelastic neutron scattering have shown that χ (ω) could be considered as representative of G(ω), with a spectrum resolution significantly higher than that obtained by inelastic neutron scattering.…”

Suppression of fast relaxation and the Raman coupling coefficient in densified silica

“…However, some interesting and important experimental information concerning the terahertz dynamics of densified silica is still lacking-to our knowledge, for densified silica there are no studies of the fast relaxation and of the behaviour of the Raman coupling coefficient, which relates the density of vibrational states to the Raman intensity [8]. The importance of studying the Raman coupling coefficient is argued in [9], with a short introduction.…”

Low-frequency vibrational excitations in a niobium–phosphate glass for Raman gain applications

“…A linear frequency dependence has been reported for a wide range of amorphous systems [24,25]. The linear increase of the coupling coefficient C(n) with frequency suggests that the origin of the Boson peak is not purely due to localized vibrations, but includes diffusional modes [26]. It remains a challenge for the theory to go beyond the Shuker-Gammon expression for the Raman scattered intensity in amorphous systems and to include correlations over distances longer than the wavelength of light and phonon eigenstates.…”