Positron scattering from O2

We report on recent cross section results for positron scattering from molecular oxygen (O-2). Total cross sections (TCSs) were measured with a positron spectrometer in the energy range from 0.1 to 50 eV and with an energy resolution of the positron beam of similar to 0.25 eV. In addition, TCSs as well as elastic and inelastic integral cross sections were computed within the independent atom model and screening corrected additivity rule approach, with both dipole and dipole plus quadrupole polarization potentials, between 1 and 1000 eV impact energy. An overall fair level of accord is found between the experimental TCS and that calculated with the model that includes the quadrupole term. Comparison to earlier measurements shows very good agreement with the present measured TCS and fair agreement with the TCS computed with our most physical model above similar to 8 eV. Conversely, we find only a marginal level of accord when comparing our experimental TCS with previous computations, while the present TCS calculated with the dipole plus quadrupole potentials appears to agree reasonably well with most of the existing theoretical results above similar to 100 eV.