dissociative recombination

Dissociative recombination is a process where electrons attach to positively charged molecular ions, forming unstable neutral molecules. These molecules then break down, converting their internal energy into kinetic energy of the fragments. This process is crucial for removing electrons in certain regions of the Earth's atmosphere, such as the D, E, and F1 layers of the ionosphere.1

The most significant reactions involve the recombination of O₂⁺ and NO⁺ ions with electrons, resulting in the formation of neutral oxygen and nitrogen atoms. Some of the energy released can excite these atoms, leading to the emission of visible light, which contributes to the phenomenon of airglow. While other forms of recombination exist, such as radiative recombination of atomic ions, they are generally less efficient than dissociative recombination in removing electrons from the ionosphere.1