Product-state-resolved study of the O^- + D₂ reaction: Anomalous vibrational-state distributions at low collision energies

We present a product vibration-state-resolved study of the reaction O^- + D₂ → OD^- + D over the collision energy range from 0.25 to 1.20 eV. At the upper end of this range, the OD^- products are primarily scattered forward, with substantial vibrational excitation. At 0.37 eV and below, the products show both forward and backward scattered contributions, primarily in the v′ = 1 state of OD^-. We argue that this anomalous behavior is inconsistent with statistical partitioning of energy in a long-lived complex and discuss these results in the context of theory and experiment on the isoelectronic F + H₂ system.