Rotational and Vibrational Excitation of H2 by Slow Electron Impact

Abstract

Abstract In a beam experiment the processes of elastic scattering, pure rotational excitation and deexcitation, pure vibrational excitation, and simultaneous rotational-vibrational excitation have been investigated for e-H2 scattering in the energy range from 0.3 eV to about 15 eV. Differential and integral cross sections have been determined in arbitrary units and calibrated on an absolute scale by normalization to absolute total cross sections. The results are discussed in terms of super-position of direct scattering, shape resonance and Feshbach resonance scattering and are compared with recent theoretical investigations. The cross sections for rotational and vibrational excitation, which are generally small for direct scattering, are greatly enhanced by a broad shape resonance near 3 eV and by Feshbach resonances around 12 eV. Characteristic differences in the excitation mechanisms are discussed.