LOW-ENERGY ELECTRON-SCATTERING FROM HALOMETHANES .4. E-CF2CL2

Differential cross sections are presented for vibrationally elastic and inelastic e-CF2Cl2 scattering in the energy range 0.5-10 eV. All four low-lying sigma* valence type resonances are observed in the measurements. The hitherto unidentified B1 (C-F sigma*) resonance has been located at 5.0-5.5 eV. A quite selective excitation of CF2 and CCl2 stretching modes is observed corresponding to the respective valence character of the resonance and in agreement with the symmetry selection rules. Resonance-enhanced vibrational excitation is found to be most pronounced in the totally symmetric resonances of symmetry type A1. The results are discussed in comparison with dissociative attachment experiments. Below 1 eV, similar to the other molecules in this series (CF4, CF3Cl), direct scattering leads to strong excitation of stretching modes according to their IR activity.