title: New Raman measurements for H2O ice VII in the range of 300 cm-1to 4000 cm-1at pressures up to 120 GPa.
abstract: Raman spectroscopic measurements for H2O ice VII have been conducted to 120 GPa at 300 K in the spectroscopic range of 300-4000 cm-1. Both moissanite and diamond anvils were used for the experiments. This overcomes the problems of overlapping spectra between the diamond anvil and sample, which had prevented the observation of the stretching modes at pressures higher than ∼23 GPa in all previous measurements. The new results reveal many bands which have not been reported before. The pressure dependences of the Raman modes show anomalous changes at 13-15, ∼27, ∼44, ∼60, and 90 GPa, implying possible structural changes at these pressures. The new results demonstrate that the predicted symmetric hydrogen bond phase X transition does not occur below 120 GPa.
authors: Geophysical Laboratory, Carnegie Institution of Washington, 5251 Broad Branch Rd. N.W., Washington, DC 20015, USA.
authors: Chang-Sheng
authors: CS
authors: Zha
authors: Department of Physics, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5B2, Canada.
authors: John S
authors: JS
authors: Tse
authors: Department of Earth and Atmospheric Sciences, Cornell University, Ithaca, New York 14853, USA.
authors: William A
authors: WA
authors: Bassett