A study on the validity of the first Born approximation for high-energy electron scattering with nitrogen molecules

Abstract

The first Born approximation is one of the most extensively used principles to deal with scattering processes, especially for fast projectiles. In the case of fast electron scattering, an empirical criterion has been proposed and widely accepted that a good match among the fast electron scattering results with higher and higher incident electron energies is enough to demonstrate the validity of the first Born approximation. However, it is found that the mutually agreed experimental generalized oscillator strength of our electron scattering measurement and the cited ones of the and states of nitrogen at a wide range of incident electron energies is obviously smaller than the generalized oscillator strength obtained by our vibronically resolved inelastic x-ray scattering experiment, in which the first Born approximation is always satisfied. Such a phenomenon indicates that the empirical criterion is not strict, and our understanding of electron scattering with multi-electron system is far from complete.