Calculation of integral cross sections for vibrationally inelastic electron-methane scattering

Integral cross sections are presented for vibrationally inelastic electron-methane scattering. They were calculated by a method which is an extension of the single-centre expansion approach previously applied by us to elastic electron-molecule scattering. The scattering wavefunction is first calculated within the adiabatic nuclei approximation, and is then substituted once into the Lippmann-Schwinger equation in order to correct for non-adiabaticity. This yields inelastic cross sections in good overall agreement with experiment. Threshold peaks are found in the cross sections for excitation of the infrared active modes. The results show that our method is a promising approach with which to investigate the inelastic scattering of electrons from polyatomic molecules.