Ubiquitous fullerenes: A detection of C60 and C70 under sonolysis of aqueous graphite colloidal suspensions

For the first time, the molecular bands of the C2 species were detected in the single-bubble sonoluminescence spectra of aqueous colloidal suspensions of graphite nanoparticles (<= 50 nm) obtained by ultrasonic dispergation upon multi-bubble sonolysis. The registration of these bands indicates that graphite nanoparticles enter the moving cavitation bubble together with solution microdroplets, where they are decomposed in the nonequilibrium plasma that occurs during ultrasonic vibrations into small fragments, including C2 radicals. Based on the conventional mechanism for the formation of fullerenes at the arc-discharge synthesis, starting from C2, under plasma conditions, we suggest that these framework molecules are synthesized in a cavitation bubble during single-bubble sonolysis of graphite nanoparticles. Indeed, the presence of the C60 and C70 fullerenes was registered in the accumulated sonolysis products of samples of suspensions of graphite nanoparticles with the chromatographic and mass-spectrometric techniques.