Electron attachement to CF$_2$ and preliminary results for C$_2$F$_5$

Experiments have been performed to investigate electron attachment to highly reactive molecular fragments CF$_2$ and C$_2$F$_5$. CF$_2$ was generated in a plasma discharge of C$_3$F$_6$ (perfluoropropene) and by reaction of hydrogen atoms with CF$_3$I. The C$_2$F$_5$ radical was generated by reaction of C$_2$F$_5$I with hydrogen atoms. Electron attachment experiments were made with ERIC, which includes a low energy pulsed trochoidal electron gun and a small linear time-of-flight mass spectrometer (Field et al., J. Phys. B 38 (2005) 255). In the case of CF$_2$ no electron attachment was observed, despite theoretical prediction of a significant dissociative electron attachment cross section (Rozum et al., J. Phys. Chem. Ref. Data 35 (2006) 267). An upper limit for the dissociative electron attachment cross section of CF$_2$ has been estimated as 5$\times$10$^{-4}$ \AA$^2$ at 1.8 eV, which is the thermodynamic threshold for F$^-$ formation from CF$_2$. In the case of C$_2$F$_5$ the data are under analysis and results will be presented at the meeting.