Measurements of Differential Cross Sections of Low-Energy Electrons Elastically Scattered by Gas Molecules. II. Scattering of 200–500 eV Electrons by Molecular Oxygen

Elastic scattering cross sections of electrons by O 2 were measured by a cross-beam method at incident energies between 200 and 500 eV and at scattering angles, θ, from 4° to 150°. The relative cross sections at 500 eV were normalized to the absolute ones measured by Bromberg at 2–40°. The absolute values at 200–400 eV were estimated by taking the ratio of the relative cross section at 90° to that measured at 500 eV and 90° with fluxes of electrons and gas molecules unaltered; they were in good agreement with those reported by Bromberg in the overlapping region (at 300, 400 eV and at 4–40°) within experimental uncertainties of about 10% for θ≤30° and 5% for θ>30°. Calculations based on the independent-atom model in which the effect of intramolecular multiple scattering was included were found to account for the measured cross sections.