Generalized oscillator strengths and integral cross sections for the valence shell excitations of trichlorofluoromethane studied by fast electron impact

Abstract

Oscillator strengths and cross sections of the valence-shell excitations in trichlorofluoromethane CFCl\(_{3}\) are of great importance in plasma etching and monitoring the greenhouse effect. In this work, the valence-shell excitations of CFCl\(_{3}\) have been studied by an angle-resolved electron energy loss spectrometer operated at a collision energy of 1.5 keV with an energy resolution of about 80 meV. Generalized oscillator strengths of the electronically excited states have been determined at an absolute scale by applying the crossed-beam based on the relative flow technique. The behaviors of generalized oscillator strengths of the valence shell excitations of CFCl\(_{3}\) have been analyzed. By extrapolating the generalized oscillator strengths to the zero limit of squared momentum transfer, the optical oscillator strengths have been obtained. The BE-scaled integral cross sections of the valence-shell excitations of CFCl\(_{3}\) have been derived from the excitation thresholds to 5000 eV with the help of BE-scaling method. The present oscillator strengths and cross sections supplement the fundamental database of CFCl\(_{3}\).

Left panel: a schematic diagram of electron energy loss spectrometer. Right panel: the typical electron-energy-loss-spectra of the valence-shell excitations of CFCl\(_3\) at an incident electron energy of 1500 eV and the scattering angles of (a) 1.5\(\circ \) and (b) 4.5\(\circ \). The valence excitations and Rydberg transitions are marked as vertical bars. (c) A 2-dimensional map of the GOS density of CFCl\(_3\) vs. the energy-loss and squared momentum transfer.