Raman intensities of single crystal ice I h

Abstract

Raman intensities of single crystal H₂O, D₂O and HOD ice I_h were measured from −4 to −150°C. The cc, aa, ca, aa′ (c is the unique axis) polarizability components were measured from 20 to 4000 cm⁻¹. Shoulders are observed on the high frequency side of the ν_OH and ν_OD bands of HOD which we attribute to combination bands between ν_OH and ν_OD and lattice modes. Intensities in the OH stretching region are interpreted using bond polarizability theory. The ratio of anistropy to mean polarizability for the OH bond was found to be 1.81. The analysis of the intensities suggests that those hydrogen bonds that statistically parallel to the c axis are slightly more linear than those that are equatorial to the c axis. The effects of intermolecular coupling of OH stretching vibrations are very evident in the spectra. However, it appears that such coupling is not the principal cause of the breadth of the isotropic part of the symmetric OH stretch band at −4°C. Evidence is presented that indicates extensive coupling of librational modes. Comparisons are made between the spectra of ice at −4°C, liquid water, and amorphous ice.