Radiative association of He(23P) with lithium cations: Π→Σ processes

- Radiative association of molecular ion HeLi+ is studied.
- Cross sections for radiative association are calculated for three processes.
- Rate coefficients are determined as functions of temperature.
- Process 1→b exhibits the largest rate coefficients up to 200 K.
- Over 200 K process 1→a exhibits the largest rate coefficients.

The radiative association processes originating in the 13Π continuum of the He (23P)+Li+ collisional system are investigated in this study. The calculations of the dynamic collision processes are based on highly accurate state-of-the-art ab initio calculations of the potential energy functions for the 13Π and the three lowest 3Σ states of HeLi+ and the associated transition dipole-moment functions. Cross-sections for the spontaneous and stimulated radiative association processes are calculated as functions of collision energy. The corresponding rate coefficients characterizing the efficiency of the formation of the molecular ion in its a3Σ+, b3Σ+, and c3Σ+ states from the initial 13Π state are obtained over a wide range of temperatures. At very low temperatures the 1→b process has a maximum rate-coefficient value of about 7.9×10−13cm3s−1, whereas process 1→a reaches its maximum value of 2.0×10−13cm3s−1 at a temperature of about 500 K. Altogether the three radiative association processes investigated here can be considered as the continuum-to-bound state radiative transition part of the total quenching of the initial collision channel.