The possibility of electron attachment to the valence 3Π state of CO
is examined using an {\it ab initio} bound-state multireference configuration
interaction approach. The resulting resonance has 4Σ− symmetry;
the higher vibrational levels of this resonance state coincide with, or are
nearly coincident with, levels of the parent a3Π state. Collisional
relaxation to the lowest vibrational levels in hot plasma situations might
yield the possibility of a long-lived CO− state.Comment: Revtex file + postscript file for one figur