ABSTRACT
After a brief survey of recent advances in gas-phase collision dynamics studies using pulse radiolysis methods, the following two topics in our research programs are presented with emphasis on the superior advantages of the pulse radiolysis methods over the various other methods of gas-phase collision dynamics, such as beam methods, swarm methods, and flow methods. One of the topics is electron attachment to van der Waals (vdW) molecules. The attachment rates of thermal electrons to O2 and to other molecules in dense gases, measured in wide ranges of both gas temperatures and pressures, present experimental evidence for electron attachment to van der Waals molecules. The results are compared with theories and discussed in terms of the effect of van der Waals interaction on the electron attachment resonance. The conclusions obtained are related with investigations of electron attachment, solvation, and localization in the condensed phase. Another topic is Penning ionization and its related processes. The rate constants for the de-excitation of He(23S), He(21p), Ne(3po), Ne(3p1), Ne(3p2), Ar(lp1), and Ar(3p1), by atoms and molecules measured in the temperature range from 100 to 300 K, provide the collisional energy dependence of the de-excitation cross sections. The results are compared in detail with theories classified according to the excited rare gas atoms in the metastable and resonant states, which present a systematic understanding of the de-excitation processes of excited rare gas atoms. For typical examples, the de-excitation process of metastable atoms, the de-excitation process of resonant atoms, and the de-excitation process by molecules containing a group IV element are discussed.
