Laboratory studies of electron attachment and detachment processes of aeronomic interest

Abstract

Techniques for the study of electron attachment and detachment are reviewed. The rate coefficients for the various processes of aeronomic interest are then discussed. The rates of three-body and dissociative attachment by thermal electrons have been successfully determined by swarm techniques and by high frequency studies of electrons produced by high energy particles and by photoionization. Collisional and associative detachment rates for thermal energy negative ions have been measured using the swarm and flowing afterglow techniques. Radiative attachment rates for some atmospheric negative ions have been calculated from measurements of photodetachment cross sections using crossed photon and ion beam techniques. Electron beam studies and measurements of ion kinetic energy have provided much useful information regarding the dissociative attachment process and the structure of molecular negative ions. Rate coefficients for low energy processes such as the three-body attachment to O₂, the radiative attachment to O, and the associative detachment of O⁻ in collisions with various atmospheric gases are reasonably well known. Other possibly important low energy processes, such as dissociative attachment to O₃, radiative attachment to O₂, and the associative detachment of O₂⁻ are less well known.