Applications to Aeronomy of Velocity Distributions in Dissociative Recombination

Dissociative recombination (DR) of ions is important in aeronomy as a loss process for ionization, as a production mechanism for excited species, as a source of neutral heat, for the production of hot atom coronas, and for the escape of species from small bodies. The velocity distributions of the neutral fragments produced in dissociative recombination are determined by the internal energy states of the ion and the product fragments, and by the kinetic temperatures of the ions and electrons. We have computed the velocity distributions produced in O ₂ ⁺ , NO ⁺ , N ₂ ⁺ , and CO ⁺ DR near the exobases of the terrestrial planets, and discuss the implications for the hot O coronas of the earth, Mars, and Venus, the hot N and C corona of Mars, the escape of oxygen and nitrogen from Mars, and the isotope differentiation that ensues.