Vibrational excitation of polar molecules by electron impact. II. Direct and resonant excitation in H2O

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Abstract
For pt.I see ibid., vol.9, no.14, p.2521 (1976). Differential scattering experiments with the crossed-beam method have been performed to study vibrational excitation of H2O by electron impact for collision energies from threshold to 10 eV. Differential and integral cross sections for the excitation of the (100, 001) and 010 modes are given in absolute units. Two distinct resonance regions are observed which are superimposed on a background of direct excitation: strong and sharp threshold resonances and a broad resonance region centred around 6-8 eV. The broad enhancement of the cross sections around 6 eV is attributed to a very short-lived 2A1 state of H2O-. The threshold resonances are interpreted as quasi-bound states in the dipole field of H2O. They are expected to be of general importance in electron-polar-molecule interactions.