Infrared Spectra of Ices Ih and Ic in the Range 4000 to 350 cm—1

Abstract

The infrared spectra of Ice Ih made from H₂O, D₂O, a mixture of 95% H₂O and 5% D₂O, and a mixture of 5% H₂O and 95% D₂O, and of Ice Ic made from H₂O, D₂O, and a mixture of 95% H₂O and 5% D₂O, have been recorded in the region 4000 to 350 cm^—1 using low‐temperature mulling techniques developed in these laboratories. The Ice Ic was made by transformation of Ices II and III, and was authenticated by its x‐ray diffraction powder pattern. The spectra of Ices Ih and Ic are identical within experimental error. The spectra of Ice Ih, while similar in their main features to those reported by earlier workers, differ significantly in detail, probably largely because much of the previous work, particularly on D₂O ice, has been done with partly vitreous ice. The usual interpretation of the bands in terms of the v₁, v₂, v₃, and v_R vibrations of isolated molecules is greatly oversimplified because intermolecular coupling is important. There are at least six (five infrared and one Raman) bands due to O—D stretching vibrations in the spectrum of D₂O Ice I, but the detailed origin is unknown. The breadth of the O–H and O—D stretching bands of HDO in dilute solution in D₂O and H₂O is interpreted as indicating a disarrangement of the oxygen positions due to the disorder of the hydrogen atoms.