High-resolution studies of electron scattering by molecular oxygen

In a new experimental system synchrotron radiation from the SRS (Daresbury, UK) has been used to photoionise Ar at threshold and to produce an electron beam with an energy resolution of about 3.5 meV (FWHM). The authors have observed the variation of the total scattering cross section of O2 in a supersonic beam over the energy range 0.1-1.3 eV. Rotational effects are strongly apparent and the results suggest that there are important contributions to the scattering from the higher partial waves l=4 and 6 as well as l=2. This apparatus shows the potential to open up the field of electron-molecule scattering at rovibrational resolution to a large variety of molecules.