Low-frequency modes in amorphous ice

Abstract The vibrational spectra of high density amorphous (hda) ice and hexagonal crystalline ice (ice Ih) have been determined for frequencies -0.10 ≤ ν ≤ 3.66THz by means of high resolution incoherent inelastic neutron scattering measurements on H 2 O samples at 11 and 80 K. The measurements at 11 K clearly reveal an excess of low-frequency modes for the amorphous phase.