Reaction dynamics from orbital alignment dependence and angular distributions of ions produced in collision of Ba(1P) with NO2 and O3.

Angular distributions, orbital alignment dependence, and energy dependence of the relative cross sections of various ions produced in crossed beams collisions of electronically excited barium with O3 and NO2 were used to explore the dynamics of these reactions. The Ba+ product from both reactions showed strong dependence on alignment of the Ba(1P) p orbital with respect to the relative velocity vector. The Ba+ was generally forward or forward-sideways scattered, with the latter favored by the dominant perpendicular orbital alignment. Similar results for Ba+ from both O3 and NO2 suggest that electron transfer is favored for large impact parameter collisions in which the Ba p orbital is directed toward the molecule at the critical configuration, regardless of the symmetry of the available orbital in the isolated molecule. BaO+2 from the O3 reaction exhibited angular distributions and energy dependences which were reminiscent of the Ba+, albeit 2 orders of magnitude lower in intensity, indicating a close relationship between these two channels. Important differences in the dynamics for the BaO+ channel were suggested in the angular distributions, which show a substantial backscattered component, as well as the alignment effects and energy dependence. These indicate that the BaO+ probably derives from neutral BaO* which is sufficiently internally excited to undergo vibrational autoionization. [ABSTRACT FROM AUTHOR]