Effect of pressure on infrared‐spectra of ice VII

The effect of pressure on the infrared spectra of H 2 O and D 2 O ice VII has been studied at room temperature and pressures between 2 and 15 GPa with a Fourier transform infrared spectrometer and a diamond anvil high‐pressure cell. Two librational modes (ν R E u 2 and ν R E u 3 ), one bending mode ν 2 A 2u 1 ), and various overtone bands are well resolved. The stretching modes, ν 1 and ν 3 , are poorly resolved due to overlap with diamond window absorption. Although ν R E u 3 shows a very strong shift to higher frequency with pressure, ν 1 and ν 3 shift to lower frequencies, and all other lines vary only slightly with pressure. Differences between the spectra of H 2 O and D 2 O are discussed.