Born Wave Calculation of Atom-Atom Inelastic Cross Sections: Description of Target Atoms by Elastic and Inelastic X-Ray Form Factors

Abstract

Total electron-loss cross sections for H atoms in collision with He, Ne, Ar, Kr, C, N, and O over the range of incident energy 1 keV-100 MeV and total ($1s\ensuremath{-}2l$) excitation cross sections for H atoms in collision with He, Ne, Ar, and Kr over the range of incident energy 0.1 keV-10 MeV are calculated by using the first Born wave approximation and assuming closure. The relevant matrix elements for the target atoms are expressed in terms of elastic and inelastic x-ray form factors. The calculations agree, within experimental error, with high-energy measurements for He, N, and O targets. Good agreement between theoretical and experimental excitation cross sections is found at energies as low as 5 keV for He, Ne, and Kr targets when the Ne and Kr calculations are scaled with a velocity-dependent parameter calculated by matching theoretical and experimental ionization data. An explanation for the velocity-dependent scaling of the theoretical cross sections for many electron target atoms at energies up to 1 MeV is presented and discussed.