Collisions of fast alkali atoms with thermal meta-fluoro-iodo-benzene
molecules were performed using the crossed molecular beam technique. T
he negative ions are extracted from the interaction region by a pulsed
voltage and their mass selection is obtained by TOF. Apart from the p
arent ion C6H4IF-, the fragment ions C6H4F-, C4H3F-, C3H2F- and C2HF-
are formed in the electron transfer collision. From the TOF spectra it
is concluded that the fragmentation of the energy-rich ions follows t
wo paths. Either the I atom is expelled, leaving the ring intact, or t
he ring is opened followed in a second step by further fragmentation.