Resolution of a discrepancy between low-energy differential cross section measurements for elastic electron scattering from O-2

There is a quite serious discrepancy in the literature, in the electron energy (E-0) range 5-10 eV, between the most recent O-2 elastic differential cross' section (DCS) measurements of Woeste et al and Sullivan et al, particularly for electron scattering angles of less than 60 degrees. This disagreement is reflected in both the shape and magnitude of the respective DCSs. In order to investigate this further we have developed an apparatus which allowed us to apply the relative flow technique, for absolute elastic DCS determination, to, in this case, the e(-) + O-2 scattering system. We found that at each of the three energies we investigated, E-0 = 5, 7 and 10 eV, the present DCS results were in excellent agreement, to within the uncertainties on the measured data, with those of Sullivan et al.