Formation and collision-induced dissociation behaviour of doubly charged gas-phase fullerene anions C,C and higher homologues. Collision-induced electron-stripping process

Doubly charged molecular anions M^2? of fullerenes are formed in the gas phase under chemical ionization conditions with isobutane as the reagent gas. The efficiency of double electron attachment increases with increasing size of the fullerenes: the C ion is the most abundant doubly charged anion in the negative-ion CI mass spectrum, although the concentration of C₇₀ was about 12% in the fullerene mixture examined. Under low-energy collision-induced dissociation conditions an electron is ejected from the doubly charged C ion resulting in the singly charged molecular anion C˙. This process appears to be the first report of the ejection of an electron (electron stripping) from a doubly charged anion in the gas phase: .