Theoretical Study of Ionization and Electron Attachment Processes in Rydberg Atom Collisions.

摘要

Theoretical studies of collisional ionization and electron attachment mechanisms involving light elements (H, He, Li) are being carried out in support of particle beam sources and beam neutralization concepts. In particular, the electronic structure of stable anions, their resonance and metastable states, and radiative and collisional processes describing their formation and/or destruction are being investigated. The volume production of atomic anions via electron-molecule dissociative attachment has previously been examined, both experimentally and theoretically, for e + H2 and e + Li2 collisions. An alternate production route, involving ion-pair formation from Rydberg-Rydberg atom collisions, is currently being investigated. The possible mechanisms include: ionic-Rydberg molecule curve crossings, collisional radiative stabilization, formation of metastable or resonance anion states followed by radiative stabilization, and associative ionization followed by secondary electron-neutral attachment processes. Recent experiments indicate that associative ionization is highly favored over direct ion-pair production in the Li system. However, others report efficient ion-pair production in collisions between heavier (Na, Rb) alkali Rydberg atoms. Several possible reaction mechanisms have been examined for these systems. Reprints. (jhd)