Gas-phase ion-molecule reactions of doubly charged fullerenes with oxygen

The gas-phase ion-molecule chemistry of doubly charged fullerene cations (C_n²⁺ where n = 46, 48, ..., 60 and 70) with neutral oxygen molecules were investigated using a triple quadrupole mass spectrometer. In this paper, we report additions to the fullerene cage structure which result in the formation of C_nO²⁺, C_nO₂²⁺, and C_nO₃²⁺ product ions from the C_n²⁺ reagent ion. In addition, we also report charge-transfer reactions resulting in the production of C_n⁺ and O₂⁺ ions, as well as reactive charge-transfer reactions generating C_nO⁺ and O₃⁺. All of these processes are a result of low energy ion-molecule collisions (0.1-49 eV_lab). The normalized intensity of the fullerene products exhibit little dependence on size of fullerene clusters examined. However, the reactivities of the fullerenes are found to be highly dependent on the collision energy and the oxygen pressure within the collision cell.