A. Lavergne

Hydrostatic optical cell with glass windows for 25 kilobar

An optical cell with three glass windows for hydrostatic pressures up to 25 kilobar has been made. Its collecting angle is 13°, and it has been used mainly for Raman spectroscopy. The fundamental Raman spectrum of diamond has been recorded.

Modified unsupported‐area hydraulic seal for pressures of 50 kilobar

An unsupported‐area static or dynamic seal for sealing hydraulic pressures up to 50 kilobar in cylindrical pressure vessels is described.

Steel pressure vessels for hydrostatic pressures to 50 kilobars

Cylindrical steel pressure vessels are described that can be used for hydrostatic pressures up to 50 kilobars. Monoblock vessels of 350 maraging steel can be used to 40 kilobars and compound vessels with an inner vessel of 350 maraging steel and an outer vessel of 300 maraging steel to 50 kilobars. Neither requires the cylinder to be end loaded, and so they are much easier to use than the more usual compound vessels with a tungsten carbide inner and steel outer vessel.

Glass windows for hydrostatic pressures of 45 kbar

Unprotected glass windows can be used at hydrostatic pressures up to at least 45 kbar on a 0.5-mm-diam aperture, and up to 40 kbar on a 0.8-mm-diam aperture.

The cracking of rubber O‐rings by hydraulic fluids at high pressures

Stretched rubber O‐rings frequently crack when pressurized by low molecular weight fluids. This appears to be due to solvent induced crazing above the glass transition.

Chemical kinetics at very high pressures. I. Two experimental techniques

Two methods of following chemical reaction rates at very high pressures by means of the electrical conductivity are described. In the first, opposed circular tungsten‐carbide anvils are used, with 12‐μm sheets of platinum silver soldered to them if the solution is too corrosive for unprotected carbide or if electrode polarization is too high, and the sample is confined by a gasket of epoxy resin and fiberglass. It can be used at pressures up to ∼100 kbar. In the second, a conductance cell was built into a hydraulic piston–cylinder apparatus, and the hydraulic fluid was pressurized by a piston. Measurements were made to 27 kbar and could be made to 45 or 50 kbar if a pressure vessel having a greater ratio of outside to inside diameter were used.

An Air‐Driven Oil Pump, a Valve, and a Connector for 20 Kilobars

A mechanical pump for 20 kilobars that is driven by a 7 kg·cm−2 air supply is described. In a test, in which it pumped fluid into a constant pressure of 20 kilobars or more at the rate of 30 strokes per minute, it made well over 300 strokes before the seal failed. A valve that will operate with 20 kilobars on either side of the stem is described. An O‐ring seal is used to seal the shaft. The torque required to close the valve is reduced by taking the thrust of the pressure on the stem by a ball thrust bearing, and is only 0.5 m·kg at full pressure. Finally, a connector for joining pieces of apparatus together without the necessity of an intermediate piece of tubing is described.

Measurement of infrared absorptivities and line shapes and the distortion of anvils in diamond‐anvil cells

The infrared transmission of diamond and other transparent anvil apparatuses that contain absorbing samples, has been calculated as a function of frequency for planar anvils that are inclined to one another or that are distorted into parabolic shapes. At frequencies where the samples are completely transparent, the height of the interference fringes decreases with increase of frequency at nearly the same rate for both parabolically distorted and inclined anvils for which the maximum difference in optical path length of the sample is the same. Hence, the distortion of anvils in a typical experimental configuration have been measured up to a mean pressure on the anvil faces of 60 kbar. They are consistent with the predictions of elasticity theory that distortions occur at the rate of about 20 μm in 500 kbar. The predicted effect of such distortions on the absorbance, integrated area, and time autocorrelation function of the dipole moment is insignificant in a well‐designed experiment, and so all these prope...