COALESCENCE REACTIONS OF FULLERENES

THE production of fullerene molecules typically involves extreme high-temperature conditions (electric arcs1, flames2 or resistive heating3), and the reactive processes involved are poorly understood. Once separated4,5, these molecules can undergo several important reactions, including formation of charge-transfer6,7 and adduct8,9 compounds, and the encapsulation of atoms10-12. Here we present evidence for coalescence reactions between fullerene molecules: mass spectrometric measurements on hot, dense vapours of small fullerenes (C60 and C70) reveal the formation of stable higher fullerenes which are multiples of the initial masses. The heat of coalescence is released through emission of small, even-numbered fragments which, in a very dense vapour, are efficiently captured by other coalesced fullerenes. These findings have implications for the mechanisms of fullerene formation and growth, and may open the way to new synthetic routes to selected higher fullerenes and encapsulation compounds.