For detachment to the 1 g X + ∑  state of NiO2, selection rules for molecular photodetachment prohibit detachment of l = 0 electrons, and p-wave detachment dominates. Conversely, transitions terminating in odd quanta along the v2 normal coordinate do so in a neutral level with contribution from an excited state of u ∏ symmetry, for which detachment can proceed via l = 0 (s-wave) transitions.