Faculté des sciences

Vibrational structures in electron–CO₂ scattering below the ² Πu shape resonance

Allan, Michael

In: Journal of Physics B: Atomic, Molecular and Optical Physics, 2002, vol. 35, no. 17, p. L387-L395

Structures of vibrational origin were discovered in vibrationally inelastic electron–CO₂ cross sections in the energy range 0.4–0.9 eV, well below the ² Πu shape resonance. They appear in the excitation of higher vibrational levels, in particular the highest members of the Fermi polyads of the type (n, 2m, 0) with n + m = 2–4. The lowest two... Plus

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    Summary
    Structures of vibrational origin were discovered in vibrationally inelastic electron–CO₂ cross sections in the energy range 0.4–0.9 eV, well below the ² Πu shape resonance. They appear in the excitation of higher vibrational levels, in particular the highest members of the Fermi polyads of the type (n, 2m, 0) with n + m = 2–4. The lowest two structures, at 0.445 and 0.525 eV, are narrow; higher-lying structures are broader and boomerang-like. The structures are absent when the antisymmetric stretch is co-excited. The structures are interpreted in terms of a wavepacket of the nuclei reflected from a potential surface of the CO₂⁻ anion in a bent and stretched geometry. A state emerging from the virtual state upon bending and stretching and the state resulting from bending the ² Πu shape resonance are discussed as possibly being responsible for the structures.