Fluorescence emission from high purity synthetic diamond anvil to 370 GPa

We report laser excited fluorescence in high purity synthetic diamond anvil to pressures of 370 GPa in a diamond anvil cell device. The nitrogen impurity level in this diamond is extremely low, and it allows us to study the stress effects on the optical transitions in diamond without interference from impurities. Pressure in the diamond anvil cell was measured by x-ray diffraction using the platinum standard. Pressure dependence of the fluorescence peak was measured between 270 and 370 GPa in the visible spectral range. The variation of excitation laser wavelength shows clear cutoff in the excitation threshold in the 514-633 nm range at 370 GPa. (C) 1996 America Institute of Physics.