The Elastic Scattering of Electrons by the Excited 2s and 2p States of Atomic Hydrogen

Abstract

The elastic scattering of electrons by H2s and H2p has been evaluated in the electron energy range 3-100 eV, the approximate method of Langer being used for large scattering phase-shifts and Born's approximation for the small phases corresponding to large values of the orbital angular momentum l. The total elastic cross sections for H2s and H2p are much larger than for the ground state H1s even at the lowest energy considered, the interpretation being that the long tails of the H2s and H2p potentials make the partial cross sections for waves of higher orbital angular momentum l very important compared with the partial S cross section. The effect of electron exchange is small even at 3 electron volts energy, an increase in cross section of 8% resulting from its inclusion, so that its effect has been neglected at higher energies.