Oscillator strengths and integral cross-sections of the valence-shell excitations of CH3Cl studied by fast electron scattering

Abstract

The generalized oscillator strengths (GOSs) of the valence-shell excitations of CH3Cl have been determined at an incident electron energy of 1500 eV and an energy resolution of about 70 meV. The momentum transfer dependence behaviors of the GOSs of the valence-shell excitations have been carefully analyzed, and the A band shows a strong dipole-forbidden characteristic. By extrapolating the GOSs to the limit of a zero squared momentum transfer, the optical oscillator strengths have been obtained, which provide an independent cross-check for the previous experimental and theoretical results. The BE-scaled integral cross sections (where B is the binding energy and E is the excitation energy) of the valence-shell excitations of CH3Cl have been derived systematically from the threshold to 5000 eV with the aid of a BE-scaling method. The results provide the fundamental spectroscopic data of CH3Cl and have important applications in photochemical modeling for atmospheric physics.