Rotational alignment in MnO*(A6Σ+) from the reaction Mn + O2

The collision energy dependence of chemiluminescence, and its polarization relative to the initial velocity vector k, has been determined for MnO*(A6Σ+) product from the Mn + O2 reaction in the range 0-1500 kJ mol-1. Analysis of the excitation function by the multiple line-of-centers approach indicates that three parallel processes, attributed to a4DJ,z8PJ (perhaps), and a6DJ atoms, contribute. All seem to involve a significant excess barrier and a forward transition state shift with increasing collision energy, suggesting that reaction proceeds via inner ionic-covalent curve crossings at short internuclear distances. The measured alignments are relatively modest, indicating a predominant contribution to MnO rotation from O-O recoil in a nonlinear Mn-O-O configuration.