Improved pressure calibration system using the ruby R1 fluorescence

Abstract

When measuring pressures in the diamond anvil cell, undersirable line broadening and wavelength shifts result if small ruby crystals are used in a calibration system designed for large ones. These effects can be eliminated through the proper choice of objective lens, condensing lens, and slit system. Using such a system, we obtained excellent results with samples as small as 30 μm. In addition, we describe the use of the spectrum from a neon light to provide an internal wavelength standard during the measurement of the ruby spectrum. This eliminates the stripchart ‐ wavelength drive synchronization error, a potential source of large errors. A calculation of the estimated error associated with a typical pressure measurement indicates that, for small ruby samples, the pressure can be determined with a precision of ±0.5 kbar.