In situ neutron scattering studies of ice under high pressure

The amplitude-weighted phonon densities of states G(E) of ices Ih, III and II obtained in situ under high pressure by inelastic incoherent neutron scattering are presented. With increasing density for different ice phases, the first maximum of the translational phonon band shifts to higher energies, while the low-energy cutoff of the librational band shifts to lower energies. The compression of ice II shows the shift of the low-energy cutoff for the librational band to higher energies. The observed shift of the librational band to lower/higher energies correlates with the increase/decrease in the nearest neighbour distances between oxygen-oxygen atoms.