Ion Velocity Map Imaging Study of the Reactive Collisions between Carbon Dioxide and Helium Ion

The reactive collision between He⁺ and CO₂ plays an important role in substance evolutions of the planetary CO₂-rich atmosphere. Using a three-dimensional ion velocity map imaging technique, we investigate the low-energy ion-molecule reactions He⁺ + CO₂ → He + CO₂⁺/He + CO⁺ + O/He + CO + O⁺. The velocity images of the products CO⁺ and O⁺ of dissociative charge-exchange reactions are distinctly different from those of charge-exchange product CO₂⁺. The remarkable features of stereodynamics are observed in the dissociative charge-exchange reaction and are attributed to the spatial alignment of the initially random target CO₂ during the He⁺ approach. Branching ratios of different channels of dissociative charge exchange are further obtained with the Doppler kinematics model, indicating a high preference for the energy-resonant channel.