Differential cross sections for electron impact excitation of the Herzberg pseudocontinuum of molecular oxygen

We report differential cross sections (DCSs) for electron impact excitation of the sum (c (1) Sigma(u)(-) +A' (3) Delta(u) +A (3) Sigma(u)(+)) of the three states that constitute the Herzberg pseudocontinuum in O(2). These DCSs were measured at seven incident electron energies in the range 9-20 eV and over the scattered electron angular range 10-90degrees. We note that this represents a far more detailed study than has hitherto previously been reported. In their review on electron-diatomic molecule scattering systems, Brunger and Buckman (Brunger M J and Buckman S J 2002 Phys. Rep. 357 215) clearly identified gaps in our knowledge for electron impact, excitation of the Herzberg electronic states. The present study rectifies this situation and, additionally, seeks to stimulate theoreticians to extend their existing integral cross section calculations, for the c (1) Sigma(u)(-), A' (3) Delta(u) and A (3) Sigma(u)(+) states, to the DCS-level.