Interaction induced light scattering spectra of amorphous solid and liquid NaOD heavy water solutions

Abstract

Low frequency translational spectra of 15 M NaOD heavy water solutions are analyzed in both liquid and amorphous phases. Confirming the results of previous findings in KOH water solutions, the analysis suggests that the spectra reflect in both phases the translational density of the states of the system. In agreement with inelastic neutron scattering experiments, these can be thought of as propagating quasi-phonon excitations. A polarization analysis of the spectra based on the results of a model recently developed for orientationally disordered crystals, allows a separation between acoustic-like and optic-like modes and clearly shows the presence of a low frequency relaxation process. The presence of this feature is also related to radiation coupling coefficients of the acoustic-like modes.