title: Optical study of H2O ice to 120 GPa: dielectric function, molecular polarizability, and equation of state.
abstract: The refractive index of H2O ice has been measured to 120 GPa at room temperature using reflectivity methods. The refractive index increases significantly with pressure on initial compression and exhibits small changes with pressure at previously identified phase transitions. Pressure dependencies of the molecular polarizability show changing slopes in different pressure regions. A general molar refractivity analysis of this change in slope reveals features at 60 GPa due to the onset of the ice VII-X transition. Band gap closure in H2O ice is constrained by the dispersion data using a single oscillator dielectric model. Sample thickness measurements obtained from interference patterns yield pressure-volume relations in excellent agreement with those measured by x-ray diffraction.
authors.affiliation: Cornell High Energy Synchrotron Source, Wilson Laboratory, Cornell University, Ithaca, New York 14853, USA.
authors.forename: Chang-Sheng
authors.initials: CS
authors.lastname: Zha
authors.forename: Russell J
authors.initials: RJ
authors.lastname: Hemley
authors.forename: Stephen A
authors.initials: SA
authors.lastname: Gramsch
authors.forename: Ho-kwang
authors.initials: HK
authors.lastname: Mao
authors.forename: William A
authors.initials: WA
authors.lastname: Bassett
mesh_terms: D004563:Electrochemistry; D008956:Models, Chemical; D044367:Phase Transition; D011312:Pressure; D013223:Statistics as Topic; D013816:Thermodynamics; D014867:Water / Q000737:chemistry*; D014961:X-Ray Diffraction
chemical_list: D014867:Water