Effect of Bond Formation on Electron Scattering Cross Sections for Molecules

Abstract

Total differential scattering cross sections were obtained experimentally for molecular hydrogen, nitrogen, and oxygen. The cross section for helium was also measured and compared with a calculated cross section to calibrate the apparatus. The calculation of the binding energy from the data was carried out and compared with previous results. It was found that the scattering method with presently available experimental and theoretical techniques cannot give values comparable in accuracy to other methods for obtaining the binding energy itself but it is useful as a test of scattering theory. The binding energy obtained for hydrogen was in good agreement with the spectroscopic value. The binding energies which were obtained for nitrogen and oxygen were considerably higher than the accepted values. The experimental uncertainties were quite large but even so the results suggest that there may be significant deviations from the simple theory. Information about the molecular densities was obtained which may serve as a useful check of theoretically calculated wavefunctions. The data were not sufficiently accurate and numerical methods have not been developed to a point where quantitative calculations of the electron densities could be made from the experimental data. The relevant theoretical quantities needed for comparison with experiment are not yet available. Qualitative arguments indicate the observed intensities are consistent with what is known about the effect of binding on molecules.