The possibility of electron attachment to the valence $^{ 3}\Pi$ state of CO is examined using an { \it ab initio} bound-state multireference configuration interaction approach. The resulting resonance has $^{ 4}\Sigma^{ -}$ symmetry; the higher vibrational levels of this resonance state coincide with, or are nearly coincident with, levels of the parent $a^{ 3}\Pi$ state. Collisional relaxation to the lowest vibrational levels in hot plasma situations might yield the possibility of a long-lived CO$^-$ state.
Categories: physics.atom-ph physics.chem-ph