Velocity of Sound and Equations of State for Methanol and Ethanol in a Diamond-Anvil Cell
J. M. BROWN 1,
L. J. SLUTSKY 2,
K. A. NELSON 3, and
L. -T. CHENG 3
1 Geophysics Program, Department of Chemistry, University of Washington, Seattle, WA 98195.
2 Department of Chemistry, University of Washington, Seattle, WA 98195.
3 Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139.
The adaptability of laser-induced phonon spectroscopy to the determination of acoustic velocity and the equation of state in the diamond-anvil high-pressure cell is demonstrated. The technique provides a robust method for measurements at high pressure in both solids and liquids so that important problems in high-pressure elasticity and the earth sciences are now tractable. The velocity of sound and the density of methanol at 25°C have been measured up to a pressure of 6.8 gigapascals. These results imply a higher density (by approximately 5 percent) for liquid methanol above 2.5 gigapascals than that given in existing compilations. The adiabatic bulk modulus increases by a factor of 50 at a maximum compression of 1.8. The thermodynamic Grüneisen parameters of methanol and ethanol both increase with increasing pressure, in contrast to the behavior of most solids.
Submitted on March 22, 1988
Accepted on May 24, 1988
