Low-energy elastic electron scattering from ethylene: Elastic scattering and vibrational excitation

Normalized experimental differential and integral cross sections for elastic and vibrationally inelastic scattering of low-energy electrons from ethylene (C2H4) have been measured over a large number of incident electron energies and angles. The differential cross sections are measured at incident energies from 0.5 to 100 eV and scattering angles from 5 degrees to 130 degrees. These measurements are made to monitor the role of the B-2(2g) (approximate to 1.8 eV) and the higher B-2(2u) + B-2(1u) + Ag-2 (approximate to 7.5 eV) resonances in the scattering dynamics. Our differential cross section measurements are in very good to excellent agreement with past measurements, and in reasonable agreement with theory as regards forward scattering. A feature in the elastic cross section at 90. scattering angle at approximate to 3.5 eV is tentatively associated with the onset of excitation of the similar to a B-3(1u) triplet electronic state. Differential cross sections for vibrational excitation of four composite energy features in ethylene are also presented from incident energies of 1.25-15 eV. These results are compared to previous measurements with satisfactory results regarding resonant behavior of these features also concerning the role of the B-2(2g) (approximate to 1.8 eV) and the higher B-2(2u) + B-2(1u) + Ag-2 (approximate to 7.5 eV) resonances in the scattering dynamics.