C 60 and C 70 fullerene isomers generated in flames. Detection and verification by liquid chromatography/mass spectrometry analyses

Fullerenes C 60 and C 70 , generated by combustion, have been shown previously to be produced in controlled laminar flames accompanied by other compounds having fullerene‐like characteristics. Analysis of these additional compounds by hith‐performance liquid chromatography, coupled on‐line with mass spectrometry has identified them as isomers of the C 60 and C 70 fullerenes. The newly observed isomers have characteristic UV spectra and are thermally unstable, undergoing conversion to the more stable fullerenes with a half‐life of about 1 h in boiling toluene (111°C). Isomers of C 60 and C 70 fullerenes previously have been studied theoretically, but not observed experimentally. The flame‐generated material also contains C 60 O and C 70 O compounds, as well as C 76 and higher carbon clusters.