Low-energy electron scattering from the X 2Π state of the OH molecule

The R-matrix method has been used to study low-energy electron impact on the X 2Π ground state of the OH molecule. We find that the X 1Σ+ ground state and first 3Π excited state of the OH- anion are bound at all geometries studied, although in the latter case the binding is very weak. The first 1Π state of the negative ion is also weakly bound for bond lengths greater than 2.5 a0. In the low-energy range studied, the vibrationally inelastic cross sections are dominated by the overall Π symmetries. The vibrational levels of the Π anion states appear as sharp resonances in the scattering. No structure was observed in the 1Σ+ symmetry, but this can be attributed to the the long lifetimes and unfavourable Franck-Condon factors of the states involved. We also present both elastic and vibrationally inelastic differential cross sections for selected scattering energies.