Dynamics of electronically inelastic collisions from 3D Doppler measurements

Flux-velocity contour maps were obtained for the inelastic collision process Ba(¹{P}₁$)+${O}₂N₂{→}Ba(³{P}₂$)+${O}₂N₂ from Doppler scans of scattered Ba(³{P}₂$) taken over a range of probe laser directions in a crossed-beam experiment. Collision with ${O}₂$ resulted in sharply forward scattered Ba${(}³P₂), with efficient conversion of inital electronic energy into O₂ internal energy and little momentum transfer. Collision with N₂ was dominated by wide-angle scattering with most of the available electronic energy appearing in product translation. The results suggest the importance of large-impact-parameter collisions and a near-resonant energy transfer in the case of O₂, while for N₂ close collisions dominate despite the presence of an analogous near-resonant channel. The results represent the first direct experimental demonstration of a near-resonant quenching process.