Oxygen ions are generated in electronically and vibrationally excited states by electron impact; the quenching of these excited states is examined by measuring collision-induced translational energy changes in the center-of-mass reference frame. The resulting center-of-mass scattering contour diagrams exhibit predominantly backward scattering asymmetry characteristic of impulsive mechanisms with some scattering symmetry indicative that a second type of mechanism proceeds via an intermediate complex which survives at least a rotational period prior to decomposing into inelastically scattered O 2 + and CH 4 . Two superelastic scattering mechanisms have been characterized for O 2 + (a 4 Π u , v=0) deexcitation, one in which all the excitation energy is released as translational energy and one in which Franck-Condon-like transitions are favored