Raman spectra of the O–H and O–D stretching vibrations of ices II and IX to 25 °K at atmospheric pressure

Abstract

The Raman scattering by the stretching modes of H2O and D2O in the ordered phases ice II and ice IX is reported for temperatures between 100 and 25 °K. The observed features are assigned to k=0 modes with the aid of polarization data from oriented crystals of D2O ice II and the normal coordinate calculations which have previously explained the infrared spectra [J. E. Bertie and F. E. Bates, J. Chem. Phys. 67, 1511 (1977)]. It is shown that normal coordinate, bond moment, and bond polarizability, calculations satisfactorily explain the frequencies and relative intensities in both the infrared and Raman bands due to the D2O stretching modes in these phases. These Raman bands are nearly insensitive to the order or disorder of the water molecules in phases of ice. The O–D stretching modes of ice IX that have large infrared intensities have weak Raman intensities, and no longitudinal optic modes can be clearly identified in the Raman spectra. The frequencies of the LO modes have been estimated for ices II and IX. The magnitudes of the LO–TO splittings suggest that the infrared transmission spectra may be broadened by reflection effects resulting from the dispersion of the refractive index, and the sharpness of the Raman bands suggests that the breadth of the infrared bands is not primarily due to Fermi resonance with high-order overtone and combination levels, as was previously proposed.

Vibrational frequencies of (H2O)nand (D2O)nclusters forn= 2 and 8: possible relevance to inelastic neutron scattering of ice

“…We note here that Tsai and Jordan [2] already recorded that all HF frequencies are real for the two cubic octamers with symmetries D 2d and S 4 but they recorded no numerical results. Out main interest here, as already mentioned, is to compare (H 2 O) 8 Table II at the HF/6-31G** level. Comparison with the inelastic neutron scattering results given in Table I of Li et al [4] gives frequencies in the range $3780-4350 cm À1 and especially the high-frequency end appears to be reflected in the results of the present theoretical study, the normal modes with the highest frequencies lying at $4220 cm À1 .…”

“…Firstly, to gain orientation as to vibrational modes, we report briefly in Section 2 the normal mode frequencies associated with the dimers (H 2 O) 2 and (D 2 O) 2 . Then in Section 3, where our major vibrational studies are reported, the cubic octamers (H 2 O) 8 and (D 2 O) 8 are both investigated. The two structures already referred to above, namely D 2d and S 4 , provide the focus.…”

“…These workers [4] also bring their findings into direct contact with both infrared [5,6] and Raman experiments [7] of ice Ih (H 2 O). Our motivation in including here studies of (D 2 O) n clusters (with n ¼ 2 and 8) is afforded by the Raman scattering by the stretching modes of both H 2 O and D 2 O in the phases ice II and IX [8].…”

“…Two other studies have also influenced us in reopening the question of hydrogen bonding in (H 2 O) 8 and (D 2 O) 8 . One is the Monte Carlo study of (H 2 O) 8 …”

“…In work about a quarter of century ago, Stillinger and David [1] had already carried out a geometry search to locate the global energy minimum for (H 2 O) 8 . They noted that (i) the general importance of hydrogen bonding in clusters had 'clearly emerged' and (ii) the relevance of water-molecule clusters to condensed-phase phenomena was 'also obvious since the peculiar properties of solid and liquid water owe their explanations to the energetic and geometric characteristics of hydrogen bonds'.…”