Acoustic velocity and refractive index of fluid hydrogen and deuterium at high pressures

Abstract

Using Brillouin scattering we have measured the pressure dependence of the accoustic velocity and refractive index of fluid hydrogen and deuterium at room temperature in a diamond anvil cell up to solidification at 55 kbars. We find good agreement between our velocities and those calculated from an equation of state given by Liebenberg et al. The refractive indices are fit by a Lorenz-Lorentz relation yielding a polarizability of 8.17±0.l×10−25 cm.3

In situ determination of mechanical properties for poly(ether ether ketone) film under extreme conditions

“…As g is known to vary between 1 and 1.2 for polymers, the ratio rapidly approaches 1 at higher pressures and independent of pressure. 10,[26][27][28] So, g is taken to be approximately 1 in this research. The isothermal variation of density with pressure is presented in Fig.…”

Equation of state and intermolecular interactions in fluid hydrogen from Brillouin scattering at high pressures and temperatures

“…The sound velocity calculated from the EOS obtained in this work fits the experimental data very well, while the extrapolation of the EOS by Mills et al 20 deviates significantly from the data at high pressures. The power low dependence, Uϭ2.25P 0.317 , given by Brody et al, 21 significantly underestimates the sound velocity. Both the extrapolation of the EOS by Mills et al 20 and the data from Pratesi et al 22 give lower density than the EOS of the present study ͑Fig.…”

“…The EOS of the fluid was subsequently examined by Brillouin scattering measurements of the sound velocity as a function of pressure to 5.35 GPa. 21,22 A significant deviation between the extrapolated Mills et al roomtemperature EOS was found. 21 The accuracy of the Brillouin data was subsequently questioned because of possible reactions of the gasket material with fluid hydrogen.…”

“…21,22 A significant deviation between the extrapolated Mills et al roomtemperature EOS was found. 21 The accuracy of the Brillouin data was subsequently questioned because of possible reactions of the gasket material with fluid hydrogen. 23 Additional Brillouin measurements were reported by Pratesi et al, 22 who derived a different functional form for the fluid hydrogen density up to 5.35 GPa at room temperature.…”

Laser Techniques in High-Pressure Geophysics

“…These measurements are important for the calculation of high-pressure equations of state used in planetary modeling studies (2). Room-temperature Brillouin scattering spectra have been obtained for normal (para and ortho) fluid H2 and D2 pressurized to the freezing point at 5.4 GPa and for the solid phases from 5.4 to 20 GPa (25,26). These data yielded the pressure dependence of the longitudinal and transverse sound velocities, from which the bulk modulus as a function of pressure and the pressure-volume equation of state were calculated.…”