LOW-ENERGY ELECTRON-SCATTERING FROM HALOMETHANES .3. E-CF3CL

Differential cross sections for elastic scattering and vibrational excitation in low-energy (0.5-10 eV) e-CF3Cl collisions have been measured. The integral elastic and the total inelastic cross section are determined. In the domain of resonance-enhanced vibrational excitation, the C-Cl and C-F stretching modes are predominantly excited according to the character and the symmetry type of the respective resonance. The strongest excitation is observed for the symmetric C-Cl stretching mode in the energy region of the A1 (C-Cl sigma*) resonance at 2.0 eV. The E (C-F sigma*) and A1 (C-F sigma*) resonances have been assigned for the first time; they are found to be located at 5.5 eV and 8.5 eV, respectively, and lead to predominant excitation of CF3 stretching modes. More details of the observed mode-selective excitation are discussed in the paper. The excitation of the IR-active modes is compared with the Born dipole approximation. The relation with dissociative attachment results is briefly discussed.