Abstract
Aims. Rate coefficients for spontaneous and stimulated radiative association of the He-2(+) molecular ion are presented as a function of temperature, considering the association with rotational-vibrational states of the ground X electronic state from the continuum states of the lowest three excited A, C, and E electronic states.
Methods. The rate coefficients are obtained from the cross sections for radiative association, which are calculated by solving the Schrodinger equation for bound and continuum states supported by the corresponding Born-Oppenheimer potential energy curves.
Results. The rate coefficients for the A -> X spontaneous process are in excellent agreement with previous calculations.
For temperatures up to about 10 000 K, the spontaneous C -> X and E -> X processes are dominant, exceeding the A -> X rate coefficient by several orders of magnitude. Stimulation of the radiative association by black-body radiation has significant influence only on the A -> X process at temperatures below 1000 K.
The black-body radiation temperature would have to be well above 50 000 K in order to have any noticeable effect on the C -> X and E -> X processes.