Charge transfer in collision of N²⁺ and He

Abstract

Charge transfer cross-sections in the collision of a doubly-charged nitrogen ion and a helium atom are evaluated with a close-coupling formalism. The charge transfer produces N⁺(³P), N⁺(¹D) and He⁺ ions via the ²Σ⁺ and ²π molecular states of NHe²⁺. We describe a method for obtaining a particular diabatic representation from a set of adiabatic dipole moments. Comparison with Landau-Zener model calculations is made and the importance of inner couplings for the production of charge transfer states is demonstrated. Collisional rate coefficients are also obtained. At 10⁴ K, the rate coefficient for charge transfer into the ground N⁺(³P) state is about 1·3 × 10⁻¹⁰ cm³ s⁻¹ and for charge transfer into the metastable N⁺(¹D) state 1·8 × 10⁻¹¹ em³ s⁻¹.