High-Pressure Diamond-Anvil-Cell Micro-Raman Spectra of Mercuric Cyanide, Hg(CN)2, and Cesium Dodecahydroborate, Cs2[B12H12]

The development of the diamond-anvil cell (DAC) has had a major impact on the field of high-pressure Raman spectroscopy. Despite its success, the DAC still has one drawback, however, in that it requires care and precision in the optical alignment of the cell and other components in the scattering chamber of the Raman spectrometer. The use of the DAC together with a micro-Raman spectrometer should overcome this limitation. Additional advantages of the micro-Raman technique lie in the high collection efficiency of the microscope optics, so that very low laser powers can be used. Low laser powers are necessary to avoid local heating and decomposition of thermally sensitive compounds. Recently, Sharma et al. have used a DAC and microscope combination to examine the stress induced in the diamond anvils under pressure, but, to our knowledge, the method has not been used to study phase transitions in solids.