The Elastic Scattering of Electrons in Molecular Hydrogen

The distribution-in-angle of electrons scattered elastically by molecular hydrogen has been investigated throughout the angular range 5^∘{} to 150^∘{} with incident electron energies varying from 30 to 912 volts. At low energies (30 to 100 volts) a single minimum occurs at about 90^∘{}. At the higher energies (200 to 912 volts) the curves all fall monotonically with angle. The experimental results are compared with theory. At low velocities of impact the agreement is excellent up to 100^∘{} when the Born formula is altered to take into account polarization. At the higher velocities the Born formula gives quite accurately the scattering up to about 60^∘{}. Beyond 60^∘{} the experimental points all fall consistently above the theoretical curves. A comparison of the theoretical atomic and molecular curves with the 100 volt experimental values is made. The curve for the molecule agrees best with the experimental data. In an attempt to detect the diffraction pattern in the experimental H₂ curves, the experimental molecular scattering coefficients were divided by the theoretical atomic scattering coefficients; this ratio was then plotted as a function of 2πmva₀sin1/2θh and compared with the predicted curve. Agreement is good to about 70^∘{} for 912 volt incident electrons.