Measurement of absolute differential cross section for the excitation of the lowest triplet state of ethene

Abstract

Absolute differential cross sections for collisions of low-energy electrons with ethene were measured. Presented are the energy dependence of the elastic cross section at 90° in the range 0.5–16 eV, the energy dependence of the cross section for the excitation of the 3B 1u lowest triplet state at 90° up to 20 eV and the angular dependence of the triplet excitation cross section at energies 1.5, 3.0 and 10 eV above threshold. The angular dependence of the cross section for excitation of the v 2 vibration at 1.95 eV is also given for reference. The electronic excitation data are compared with the results of recent ab initio scattering calculations of Rescigno and Schneider and Sun, Winstead, McKoy and Lima. The calculated cross sections are found to be about two times larger than experiment in absolute magnitude and to reproduce qualitatively correctly the main experimental features both in the energy and the angular dependence.