Figure 4. Raman spectra and SEM images of the recovered samples and starting HOPG at ambient conditions.

(a) Raman spectra of graphite samples quenched from various high pressures. For comparison, Raman spectra of diamond, bulk HOPG starting material, and powdered graphite are also shown. The D, G, D' and D* bands are labeled. (b) SEM image of bulk HOPG starting material. (c) SEM image of sample recovered from cold-compression to 50 GPa. The scale bars represent 2 μm.