Method of cross section calculation for vibrational excitation of polyatomic molecules by slow electrons: Analysis of the role of Fermi resonance in the CO2 molecule

The method of calculation of the vibrational excitation of polyatomic molecules is formulated in terms of the local theory. The CO2 molecule is considered as an example. The influence of Fermi resonance between the symmetric stretching and bending modes on the vibrational-excitation cross section is considered. It is shown that, owing to Fermi resonance, the cross sections are markedly redistributed over the different nearly degenerate final vibrational states, whereas the fine structures of the energy-dependent cross sections are visibly smoothed out. Applications of the suggested algorithm to some other problems are also considered. 21 refs., 6 figs., 2 tabs