R-Matrix Calculation of Electron Collisions with Molecular Oxygen in Its Electronically Excited States

Low-energy electron collisions with the X3 Sigma g- ground state and a1 Delta g and b1 Sigma g+, the Herzberg states (c1 Sigma u-, A ' 3 Delta u, and A3 Sigma u+), and B3 Sigma u-excited states of the O2 molecules are studied using the fixed-nucleus R-matrix method. Integral elastic scattering and electronic excitation cross sections from the X3 Sigma g- ground state overall agree well with the available experimental and theoretical results. The electronic (de-)excitation cross sections for the electron impact with the Herzberg states and the B3 Sigma u-state are reported. The value of elastic cross sections for the six excited states decreases with the increment of electron energy, except for the resonance peaks. As the case of excitation from the X3 Sigma g- ground state, the O2- 2 Pi u resonance makes a dominant contribution to the (de-)excitation cross sections from the a1 Delta g, b1 Sigma g+, and the Herzberg states. The magnitude of the de-excitation cross sections at the location of the 2 Pi u resonance from the Herzberg states to the ground state is about 2 to 8 times those of the excitation cross sections for the corresponding excitation transitions. These results should be significant for models of oxygen plasma and the dynamics of the Herzberg states of molecular oxygen in the earth's atmosphere.

Automated summary

Low-energy electron collisions with O2 molecules at different energy levels were studied using the fixed-nucleus R-matrix method, showing that the elastic cross sections for various excited states decrease with increasing electron energy, except for resonance peaks.