Formation of gaseous negative ions of fluoro and trifluoromethyl derivatives of C60 fullerene studied by Knudsen-cell mass spectrometry

Experimental procedures are described for producing negative ions of fluoro and trifluoromethyl derivatives of C-60 in the vapor phase and characterizing them by Knudsen-cell mass spectrometry. Some common aspects of the formation of such ions are established, and the associated ion-molecule equilibria are investigated. Electron affinity data are presented for C-60(CF3)(2n) molecules. It is shown that, upon ionization, the fluorofullerenes tend to loose one or several fluorine atoms.