Elastic and inelastic cross sections for positron scattering from molecular oxygen

Elastic, vibrational and rotational cross sections for positron scattering from molecular oxygen are reported within the close-coupling formalism, using a three-dimensional positron-target potential energy surface. The present elastic values show good agreement with a recently reported theoretical prediction and helps to better understand the observed discrepancies between theory and experiment for energies below 1 eV. For energies up to the opening of the positronium channel, details of the elastic cross section are also discussed. The cross section for excitation of the fundamental vibrational mode shows a sharp onset at threshold followed by a peak, similar to the observed in our previous work for the N-2 target, although roughly three times greater than the last one. The rotational excitation cross sections for positron scattering from O-2 are reported.