Low energy electron collisions on OCS: differential vibrational cross sections and S− production around 1 eV Original Research Article

The low energy vibrational excitation in OCS has been re-examined. The angular dependences of the vibrational cross sections in the 2Π resonance region are shown to be proportional to 2 - cos2θ for π vibrational modes, and to 1 + 7 cos2θ for σ modes. The threshold spectrum (Eresidual = 0 eV) reveals that, in the bending series below 0.5 eV, the vibrational modes of σ symmetry are more excited than the π modes. Indeed the vibrational excitation cross sections recorded for a few vibrational modes, show a peak at threshold for the σ modes but not for the π ones. We have also observed a new structure in the S−/OCS dissociative attachment cross section.