Comparison of Raman spectra of (a) and (b). The two Raman active modes are identified for the two structures. Differences are observed and can be used as a fingerprint.
Diamond anvil cell experiments with (a) and (b). These graphs show several spectra performed at different pressures in the diamond anvil cell: no load, 2, 10, 20, and , and the spectrum performed after the opening at the end of the test. Comparisons of the shift of the for two structures are made.
Static Hertzian contact experiment with (a) and (b), detail of the mode shift. The spectra were performed at different loads in the contact: pristine powder, closed contact, 1, 5, and , and load released.
Contact pressures determined from Raman shift observed on the Raman spectra during contact static experiments with (a) and (b). These pressures are compared to those calculated from the Hertz theory (contact mechanics).
Electron micrographs of . (a) Pristine material. We can observe that are partially faceted. (b) Damaged . The arrow shows the presence of exfoliated sheets.
Fullerenes' behavior inside the two kinds of experiments. In the diamond anvil cell (a), fullerenes are submitted to hydrostatic pressure and no structural modifications occur. Inside an Hertzian contact (b), fullerenes are exposed to anisotropic pressure and external sheets are exfoliated.
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