Negative Ion Resonance Electron Scattering from Oriented, Physisorbed O2
The physisorption of diatomic molecules on a crystalline solid surface at low temperature provides a means of orientating the molecular axis and thus studying low energy electron scattering from an oriented molecule. The cross-section for vibrational excitation of one monolayer of O2 on graphite at 25K has a peak near 9eV electron energy. The angular distribution of vibrationally inelastic electrons has been measured; comparison with calculated distributions, which include interference effects arising from multiple elastic electron scattering within the molecular layer, allows us to determine the orientation of the O2 molecule on the surface and to identify the partial wave content of the resonance. The dominant partial wave (pπ) is consistent with the 2Πu compound state but not the 4Σu.
KeywordsAngular Distribution Partial Wave Vibrational Excitation Molecular Axis Electron Energy Loss Spectrum
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