Elastic scattering of low-energy electrons by randomly oriented and aligned molecules - Influence of full non-spherical potentials

Elastic scattering of low (10-50 eV) kinetic energy electrons from free dia tomic molecules is studied using a single-center expansion of the full mole cular potential. Dynamic exchange and polarization are included in a local form. The calculated elastic differential scattering cross-sections (DCS) f or electron impact on CO and N-2 are in good agreement with available exper imental data. The importance of using the full molecular potential instead of a two-center potential approach is pointed out. These corrections are sm all for energies above 50 eV; but they become increasingly important at low er energies. When discussing the angular distributions of elastically-scatt ered electrons from oriented molecules (like surface adsorbates), we show t hat these corrections are particularly significant. The results have implic ations for other electron scattering problems such as those encountered in low-energy photoelectron diffraction from both core and valence levels. (C) 2001 Elsevier Science B.V. All rights reserved.