Experimental Techniques

The Raman experiments were performed in a backscattering geometry at room temperature using 514.5 nm (2.41 eV), 496.8 nm (2.496 eV), and 488 nm (2.541 eV) lines from an argon-ion laser and the 632.8 nm (1.96 eV) line from a He-Ne laser. The Raman spectra were analyzed using a JY T64000 micro-Raman system with a liquid nitrogen cooled CCD detector. The pressure-dependent measurements were carried out using a diamond anvil cell (DAC) with a 4:1 mixture of methanol and ethanol as the pressure-transmitting medium. Figure 12.2 shows a schematic diagram of the high-pressure experimental setup. A small sample with dimensions of ~100 x 100 x 30 |j.m3 was prepared by mechanical polishing and cutting before

Figure 12.2. A schematic diagram of the high-pressure Raman experimental setup.

loading into the gasket of the DAC. The applied pressure was measured by the shift of the ruby R1 line [21]. Because the frequency of the first-order Si Raman peak shows a blue shift with a pressure coefficient of 0.52 cm-1/kbar [22], we can use it as an internal pressure calibration. The signal collected from DAC is at least an order of magnitude weaker than that obtained outside the DAC.

Was this article helpful?

0 0
Solar Power

Solar Power

Start Saving On Your Electricity Bills Using The Power of the Sun And Other Natural Resources!

Get My Free Ebook


Post a comment