Low-Energy Elastic Scattering of Electrons by Oxygen and Nitrogen

Abstract

The elastic scattering of slow electrons by O and N is calculated by the method of phase shifts. The Hartree potential gives a cross section (2×10−15 cm2) for O on the order of magnitude needed to agree with the experiments of Lamb and Lin in air. Since the Hartree potential is known to be too weak as it neglects exchange and polarization, this agreement is considered fortuitous. Exchange forces are introduced by a new approximation based on a suggestion of Slater for bound atomic states. The exchange approximation is adjusted to fit the more elaborate calculation of Bates and Massey for zero energy and zero polarization. The addition of a reasonable polarization force results in an acceptable potential and closer agreement with experiment. A similar calculation is made for nitrogen. In this case the Hartree potential alone gives a cross section which is too large. The inclusion of exchange and polarization leads to better agreement with the measurements in air.