The hypothesis that fullerenes grow in a carbon plasma by the addition of ${\mathrm{C}}_2$ units (the “fullerene road”) has been widely acclaimed as the most plausible mechanism for formation of larger fullerenes including ${\mathrm{C}}_{60}$ and ${\mathrm{C}}_{70}$. Calculations suggest that the association of ${\mathrm{C}}_2$ with fullerenes proceeds through two classes of intermediates, “sticks” and “handles.” Here we report the observation of these species using high-resolution ion-mobility measurements for ${\mathrm{C}}_n$ cations generated by laser vaporization of graphite and laser desorption of ${\mathrm{C}}_{60}$. Sticks with up to eight-atom chains have also been found.

• Received 5 August 1999

DOI:https://doi.org/10.1103/PhysRevLett.84.2421