Electron–Atom and Electron–Molecule Collisions

Abstract

Electron–atom and electron–molecule collision processes play a prominent role in a variety of physical systems such as electrical discharges, electron-beam lasers, plasma processing, and fusion devices. They are also significant in various environments, such as planetary atmospheres and astrophysical and solar plasmas. Early studies of these interactions contributed significantly to the understanding of the quantum nature of matter. Experimental activities in this field, initiated by Franck and Hertz 1 , flourished in the 1930s and, after a dormant period of about a quarter of a century, had a renaissance in the latter half of the century. More recently, sophisticated developments in experimental and theoretical techniques have led to increased physical insight and data production. When electrons collide with atomic or molecular targets, a large variety of reactions can take place (Sect. 67.1.1). We limit our discussion to electron collisions with neutral atoms and molecules, where single collision conditions prevail. Furthermore, we discuss only low-energy (threshold to few hundred eV) impact processes where the interaction between the valence-shell electrons of the target and the free electron dominates. Comprehensive discussions on electron–atom (molecule) collision physics can be found in the books of Massey et al. 2 , McDaniel 3 , and the volumes of Advances in Atomic and Molecular (since 1990 Atomic, Molecular and Optical) Physics. The latest developments are usually published in Physical Review Letters, Physical Review A, Journal of Physics B, Journal of Chemical Physics, European Physics Journal D and Journal of Physical and Chemical Reference Data, and are presented at the biannual International Conference on Photonic, Electronic and Atomic Collisions (ICPEAC).