New routes in the formation of positively charged fragments upon electron attachment

Electron-driven reactions of CF₃CH₂F have been studied focusing on the formation of the parent cation, CF3+ and CH₂F⁺ (C–C bond cleavage) fragments as a function of the electron energy. For the three referred cations, an unpredicted shoulder structure is observed in the ion yield between 12 and 20 eV, indicating a resonant process (electron attachment). Viewing the observations as the result of a competition between the expected dissociative electron ionization and a dissociative electron attachment, we propose a new route where the formation of the transient anion, under two autodetachments, ultimately triggers the formation of positively charged fragments. The reaction e^-+ AB → AB ^{- ∗}→ AB ^∗+ e^-→ A ⁺+ B + 2 e^- is supported by both experimental data and scattering calculations. Graphical abstract: [Figure not available: see fulltext.]