Proton order-disorder transition of ice investigated by far-infrared spectroscopy under high pressure

Citation
M. Kobayashi et al., Proton order-disorder transition of ice investigated by far-infrared spectroscopy under high pressure, J PHYS-COND, 10(49), 1998, pp. 11551-11555
Citations number
7
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Apllied Physucs/Condensed Matter/Materiales Science
Journal title
JOURNAL OF PHYSICS-CONDENSED MATTER
ISSN journal
0953-8984 → ACNP
Volume
10
Issue
49
Year of publication
1998
Pages
11551 - 11555
Database
ISI
SICI code
0953-8984(199812)10:49<11551:POTOII>2.0.ZU;2-L
Abstract
In situ high-pressure measurements of the far-infrared absorption spectra i n ice VII and VIII covering the region of translational lattice modes are m ade by utilizing an infrared beam line of synchrotron radiation at the Inst itute for Molecular Science (Okazaki). Although the lattice dynamics are al most same for both the phases, large spectral changes are observed on the o ccasion of the proton order-disorder transition. In the proton disordered p hase (ice VII), absorption spectra reflecting a density of states of lattic e modes are obtained. The proton ordered phase (ice VIII) gives rise to an absorption peak due to the optical phonon at the Gamma point. The anomalous pressure dependence of the phonon energy in ice VIII indicates the occurre nce of a lattice instability below 2.7 Cpa with decreasing pressure, which is supported by the recent neutron inelastic scattering experiments by Bess on et al.