Pulsed laser Raman spectroscopy in the laser-heated diamond anvil cell

We describe the design and operation of a spatially-filtered Raman/fluorescence spectrometer that incorporates a pulsed 532nm laser excitation source and a synchronized and electronically gated CCD detector. This system permits the suppression of undesired continuous radiation from various sources by a factor of up to 50 000 providing the possibility of acquiring Raman signals at temperatures exceeding 5000K. We present performance comparisons of this system with that of a state-of-the-art conventional CW system using a 458nm excitation source. We also demonstrate that the pulsed system is capable of suppressing an impurity-induced (single nitrogen defects) fluorescence in diamond, and further suggest that this capability can be used to suppress the stress-induced fluorescence in diamond that may appear at pressures near or above 150GPa. This work suggests that Raman spectroscopy under conditions of very high temperatures (to 5000K) and/or ultrahigh pressures (to 300GPa) is entirely viable.