The isomeric pentane system, as well as other systems, was studied as a function of pressure via Brillouin scattering. Room temperature experiments were carried out at different scattering angles in a Merrill-Bassett diamond anvil cell. The scattered light was analyzed using a nine-pass tandem Fabry-Perot interferometer. Isopentane and mixtures such as 1:1 pentane/isopentane vitrify at 7.4 GPa as determined by a change in the slope of the sound velocity vs. pressure curve, and in some cases by the onset of shear modes. From the sound velocity data and thermodynamic considerations, one can extend the equations of state for these systems to high pressure. When the acoustic shear mode is measureable, it is possible to calculate the high frequency shear modulus from the data. These calculations combined with the measured viscosity allow the determination of the shear relaxation time over a broad range of pressures.
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Ceramics and Composites
- Condensed Matter Physics
- Materials Chemistry