Associative detachment in collisions between negative halogen ions and hydrogen atoms

The associative detachment reaction is studied theoretically in the thermal energy range for Cl - and F - ions colliding with hydrogen atoms. The interaction of the outer low-energy electron with the hydrogen halide molecule is described in the zero-range-potential approximation, which allows an exact treatment of the collision process. In the case of F - projectiles, the molecular data needed are taken from the ab initio calculations of Segal and Wolf (1981); for the Cl - projectile, these molecular data are partly fitted to reproduce the experimental data. The relative population of the final levels, or equivalently the sharing of the exothermicity of the reaction between the various degrees of freedom, is thoroughly investigated; it appears that most of the available energy goes into the vibration of the final molecule. Comparison with the experimental data of McFarland et al. (1975) and Zwier et al. (1980) is presented.