O ++C 60· C 60O + production and decomposition, charge transfer, and formation of C 59O +. Dopeyball or [CO@C 58+
The reaction of O + with C 60 has been studied over a collision energy range from 2 to 77 eV. At collision energies below 10 eV, we observe formation of the metastable C 60O + adduct, as well as charge transfer and chemically driven fragmentation processes. As energy increases, the adduct decomposes to form C +60, C +59 and C +58. At higher collision energies, in addition to the expected series of C +60-2 n fragments, we observe odd-sized fullerene oxides, C 69-2 nO +, n=0-4. These could be either O-substituted fullerenes (dopeyballs) or endohedral CO complexes of the form [CO@C 58-2 n] +. Our evidence is most consistent with the endohedral CO structure, which would be the first example of a molecule collisionally trapped inside a fullerene. We also examined collisions of CO + with C 60, however only C +60-2 n fragment ion production is observed.