Low-energy total electron scattering in the methyl halides CH3Cl, CH3Br and CH3I

Absolute integral and backward total scattering cross-sections are reported for the polar molecules CH3Cl, CH3Br and CH3I at electron energies from ∼10 meV to 0.7 eV for backward scattering and 20 meV to 9.5 eV for integral scattering. Below 1–2 eV, the present integral cross-sections are significantly higher than data in the literature. The Born point-dipole cross-sections for rotationally inelastic scattering have been calculated and are compared with the experimental total scattering cross-sections. Discrepancies give a measure of pure elastic scattering at very low energy. Data for CH3I demonstrate the presence of strong resonant elastic scattering and dissociative attachment at low energy.