HR: 1340h
AN: MR23A-1022    [Abstracts]
TI: Investigation of the High P-T Behavior of Binary Hydrogen-Helium Mixtures
AU: * King, S L
EM: slking@purdue.edu
AF: Purdue University, 550 Stadium Mall Dr., West Lafayette, IN 47907, United States
AU: Goncharov, A F
EM: goncharov@gl.ciw.edu
AF: Carnegie Institution of Washington, 5251 Broad Branch Road NW, Washington, DC 20015, United States
AB: The gas giant planets are currently thought to be composed primarily of hydrogen-helium mixtures, with the interiors of these planets potentially composed of metallic hydrogen. The phase diagram for one such binary H₂-He mixture (70% He and 30% H₂) was investigated in the pressure-temperature region of 300- 500 K and 2-10 GPa with the goal of developing a satisfactory experimental methodology for mapping the temperature-pressure-composition space of the H₂-He system. The gas mixture was loaded into a diamond anvil cell, with both resistance laser heating methods employed to access high temperatures. Raman spectroscopy was then used to monitor the temperature and pressure dependence of the H₂ vibron. We find that the H₂ vibron frequency of the H₂-He mixture (4305 cm^-1) is significantly higher than that of pure H₂ (4200 cm^-1) at 6 GPa, indicating that He dilutes H₂ and disrupts the intermolecular coupling. Preliminary studies of the data at higher temperatures (> 370 K) indicate that the vibron frequencies tend to follow the same general trend with pressure as observed at lower temperature. The results of this study agree well with similar studies carried out in different pressure and temperature regimes.
DE: 3924 High-pressure behavior
DE: 3934 Optical, infrared, and Raman spectroscopy
DE: 5724 Interiors (8147)
DE: 6220 Jupiter
SC: Mineral and Rock Physics [MR]
MN: 2007 Fall Meeting