Additivity Rule for Electron--Molecule Total Cross Section Calculations at 50--5000eV: A Geometrical Approach
Additivity Rule for Electron-Molecule Total Cross Section Calculations at 50-5000 eV： A Geometrical Approach

To quantify the changes of the geometric shielding effect in a molecule as the incident electron energy varies, we present an empirical fraction, which represents the total cross section (TCS) contributions of shielded atoms in a molecule at different energies. Using this empirical fraction, a new formulation of the additivity rule is proposed. Using this new additivity rule, the TCSs for electron scattering by CO2, C2H2, C6H12 (cyclo-hexane) and C8H16 (cyclo-octane) are calculated in the range 50--5000eV. Here the atomic cross sections are derived from the experimental TCS results of simple molecules (H2, O2, CO). The quantitative TCSs are compared with those obtained by experiments and other theories, and good agreement is attained over a wide energy range.