Total electron-scattering cross sections for CHF3, C2F6, C3F8, and c-C4F8

The total electron-scattering cross section has been measured for 0–20 eV electrons incident upon CHF3, C2F6, C3F8, and cyclo-C4F8. The cross sections all have a broad maximum for electron energies near 9 eV, with more or less sharper peaks attributed to temporary-negative ion resonances at lower energies. For the linear molecules a resonance in the 3–6 eV range is associated with electron capture into the lowest unoccupied orbital. The shape of the cross section for the cyclic compound implies a stable ground-state negative ion.