Attachment of Two Electrons toC60F48: Coulomb Barriers in Doubly Charged Anions

The highly fluorinated chiral $C_{3h}$ molecule ${\mathrm{C}}_{60}$ ${\mathrm{F}}_{48}$ was observed to sequentially attach two electrons in the gas phase to produce ${\mathrm{C}}_{60}$ ${\mathrm{F}}_{48}^{2-}$ and ${\mathrm{C}}_{60}$ ${\mathrm{F}}_{46}^{2-}$ + ${\mathrm{F}}_2$. The first electron affinity (EA) of ${\mathrm{C}}_{60}$ ${\mathrm{F}}_{48}$ was measured to be 4.06 ± 0.3 eV. The first and second EA were calculated to be E${\mathrm{A}}_1$ = 5.07 eV and E${\mathrm{A}}_2$ = 2.27 eV for the more symmetric $D_{3d}$ isomer. The dianion was found to be more stable with respect to electron detachment than the singly charged anion. This remarkable stability of the dianion is attributed to a potential barrier resulting from the long range Coulomb repulsion and short range electron-molecule binding.