LOW-ENERGY-ELECTRON COLLISIONS ON OCS - DIFFERENTIAL VIBRATIONAL CROSS-SECTIONS AND S-PRODUCTION AROUND 1-EV

The low energy vibrational excitation in OCS has been re-examined. The angular dependences of the vibrational cross sections in the 2PI reso nance region are shown to be proportional to 2 - cos2theta for pi vibr ational modes, and to 1 + 7 cos2theta for sigma modes. The threshold s pectrum (E(residual) = 0 eV) reveals that, in the bending series below 0.5 eV, the vibrational modes of sigma symmetry are more excited than the pi modes. Indeed the vibrational excitation cross sections record ed for a few vibrational modes, show a peak at threshold for the sigma but not for the pi ones. We have also observed a new structure in the S-/OCS dissociative attachment cross section.