Vibration properties of low-fraction hydrogen in deuterium ices

Inelastic incoherent neutron scattering spectra of D₂O high-density amorphous (hda) ice, ice-VIII and ice-II mixed with small amount of H₂O (<5%) have been measured recently on high-energy transfer spectrometer at Rutherford Appleton Laboratory (UK). The hydrogen atom on D₂O ice lattices has three distinguished vibrational modes, two bending at low frequencies and one stretching at high frequencies, and their frequencies are slightly different for different phases of ice. It was found that the lower one of the bending modes is located at ~95meV for hda-ice, at ~95meV for ice-VIII and at ~96meV for ice-II and they are all lower than the value of 104meV for ice-Ih. It was also measured that the O-D and O-H covalent bond stretching modes of ice-VIII are at ~315 and ~425meV, ice-II at 307 and ~415meV, hda-ice at 312 and ~418meV, respectively. They are significantly higher than the values of ice-Ih at ~299 and ~406meV, respectively.