Mid-infrared spectra of deuterated ices at 10°K and interpretation of the OD stretching bands of ices II and IX

The infrared absorption bands due to the OD stretching vibrations of D2O and HDO, and to the D2O rotational vibrations, in the ordered forms of ice, ice II and ice IX, change little between 100 and 10°K. The frequencies and relative intensities of the zero-wave-vector OD stretching vibrations of these phases have been calculated in the harmonic and bond-moment approximations, and explain the main features of these bands. The features are less well resolved than is expected for an ordered molecular crystal, and this ’’hydrogen bonding effect’’ is attributed primarily to Fermi resonance between the fundamental states of the OD stretching vibrations and the isoenergetic continuum of high-order, overtone, and combination states of lower-frequency vibrations. The frequency of the OD stretching vibrations of HDO molecules isolated in H2O ice 1h at 10°K is 2413.5±1 cm−1.