Sub-Excitation Electron Interactions in Rare Gases: I. Evidence for the Time Evolution of the sub-Excitation Spectrum

摘要

The production of the '2p' electronic excited states of the rare gases neon, argon, krypton and xenon has been studied using picosecond pulse radiolysis techniques. At pressures below about 5 torr, the emission from these excited states shows a pressure dependent growth-decay pattern. Kinetic analysis of the growth-decay curves reveal formation rate constants which are all greater than 10 sup 12 M/sup /minus/1/sec/sup /minus/1/. These observations preclude atom-atom collisional processes and support an excitation mechanism involving collisional energy loss from electrons. It is thus concluded that the secondary electron spectrum in pure rare gases at pressures below a few torr takes a few nanoseconds to degrade to energies below that of the lowest excited state. This time scale therefore (by definition) corresponds to the time needed to form subexcitation electrons. In 1 atmosphere of rare gas the time taken would be of the order of 20--30 picoseconds. 5 refs., 4 figs., 1 tab. (ERA citation 14:020928)