Electron attachment to radicals and other reactive molecules

Electron attachment to highly reactive fluorocarbon species C$_2$F$_5$ and CF$_2$ has been studied experimentally with a TEM-TOF apparatus (TEM- Trochoidal Electron Monochrator; TOF - Time-of-Flight mass spectrometer; Field et al., J. Phys. B 38 (2005) 255). These reactive molecules have been generated {\it in situ} by fast atom reactions and by passing fluorocarbon precursors through a microwave discharge. In the case of C$_2$F$_5$ low energy electron attachment is observed with the formation of F$^-$ at close to zero electron energy, however, no electron attachment to CF$_2$ 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$_2$. (Graupner et al., New J. Phys. 12 (2010) 083035).\\[4pt] Work done in collaboration with Karola Graupner and Sean Haughey, Centre for Plasma Physics, Queens University, Belfast; Christopher Mayhew, Dept. Physics, University of Birmingham, UK; and Judith Langer, Institut fur Optik und Atomare Physik, TU Berlin, Germany.