ELECTRON-TRANSFER IN COLLISIONS OF POTASSIUM ATOM WITH META-FLUORO-IODO-BENZENE

Collisions of fast alkali atoms with thermal meta-fluoro-iodo-benzene molecules were performed using the crossed molecular beam technique. The negative ions are extracted from the interaction region by a pulsed voltage and their mass selection is obtained by TOF. Apart from the parent 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 two paths. Either the I atom is expelled, leaving the ring intact, or the ring is opened followed in a second step by further fragmentation.