Stereodynamics Observed in the Reactive Collisions of Low-Energy Ar+ with Randomly Oriented O2

Stereodynamics of the collisional reaction between mutually aligned or oriented reactants has been a striking topic of chemical dynamics for decades. However, the stereodynamic aspects are scarcely revealed for the low-energy collision with a randomly oriented target. Here in the dissociative charge-exchange reaction between randomly oriented O-2 and low-energy Ar+, we, using the three-dimensional ion velocity map imaging technique, clearly observe a linear alignment and a nearly isotropic distribution of the O+ yields along the collision axis. These observations are rationalized with the Doppler kinetic models in which the O-2 bond is assumed to be parallel or unparallel to the collision axis of the large impact parameter collision. The linearly aligned O+, as the predominant yield, is produced in the parallel collision, while a rotating O-2(+), as the intermediate in the unparallel collision, leads to the isotropic distribution of O+.

Automated summary

The study investigated the dissociative charge-exchange reaction between randomly oriented O-2 and low-energy Ar+ using the three-dimensional ion velocity map imaging technique. It found that the O+ yields are linearly aligned along the collision axis and exhibit a nearly isotropic distribution when the collision axis is assumed to be parallel or unparallel to the O-2 bond.