HIGH-RESOLUTION ELECTRON-SCATTERING FROM CARBON-DIOXIDE

The energy dependencies of the elastic scattering cross section and of the electron impact excitation of the three fundamental vibrational modes of CO2 have been investigated in the energy region below 1 eV. The elastic scattering cross section shows a rapid increase with decreasing impact energy, and all three vibrational excitation functions show sharp threshold peaks. The onsets and the widths of these peaks are much sharper and narrower than previously reported. Comparison with theoretical models shows that the simple Born approximation does not adequately describe the excitation of the two infrared-active modes. The virtual state model in its present form also fails to reproduce our excitation functions.