Dissociative and non-dissociative electron attachment processes studied using Rydberg atom techniques
Finch, Carla D.
Dunning, F. B.
Doctor of Philosophy
Dissociative and non-dissociative electron attachment processes are investigated via electron transfer in collisions between velocity selected Rydberg atoms and target molecules. Measurements of the velocity distribution of the reaction products and of the decay of product negative ions during passage to the detector provide information about the energetics of the interactions and about the lifetime of the intermediate negative ion formed. Collisions with CBrCl 3 result in a dissociative process producing Br- and Cl- as products. Br- production occurs through two reaction channels. The intermediate negative ion dissociates immediately in one channel, but the second channel involves a long-lived intermediate having a lifetime of ∼5 ps. A single reaction channel produces Cl -, but it is uncertain if the process is immediate or if it occurs after a few vibrational periods of the intermediate ion. Non-dissociative electron attachment occurs with C7F14 and with C 6F6. Collisions with C7F14 lead to the production of free electrons and of long-lived (tau > 100 mus) C 7F14-- ions. The free electrons, which result from autodetachment, are all created within a very short time period (tau ≲ 15 ps) following initial electron capture. Collisions with C6F6 result in the formation of C6F 6-* ions that have a broad range of lifetimes against autodetachment. Data analysis and model calculations are discussed in addition to possible theoretical models explaining the results. Future experimental studies are also proposed.
Molecular physics; Atomic physics