Laser productions of fullerene ions promoted by additive compounds in carbon targets

By doping various compounds, which can dissociate free radicals covalently bonding with carbon clusters, into the carbon target, C-60(+) and other ful lerene ions were produced from direct laser vaporization. The compounds do not provide the carbon atoms, and to exhibit the promotion effect, only ver y small amounts of the species need to be doped, so the free radicals disso ciated from the compounds behaved as catalysts in the formation process of the fullerenes. Among the various free radicals, free chlorine atom was fou nd to be most effective in promoting fullerene formation. After doping the compounds, fullerene ions can be created from different forms of carbons, s uch as amorphous carbon, glassy carbon, graphite, and even diamond. Based o n the experimental results, the catalysis mechanism of the free radicals an d the formation process of fullerenes are suggested.