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

We report integral cross sections (ICSs) 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 ICSs were measured at seven incident electron energies in-the range 9-20 eV in order to investigate for the existence of the strong resonance feature predicted by earlier R-matrix calculations. No such structure was observed in this letter.