Electron Removal in Krypton Afterglows

Abstract

The decay of the electrodeless microwave discharge in samples of Kr at 0.5- to 25-mm Hg was studied by the recently developed techniques of electron-concentration, optical spectrographic, and optical photometric measurements as a function of time after termination of the exciting fields out to a maximum of 15 msec. The Kr samples unavoidably contained traces of Xe estimated to be of the order of 0.01 to 0.1 mole percent, and such quantities of Xe were found to enter importantly into the afterglow processes of recombination and radiation in the pressure range 6 to 25 mm Hg. The observations are interpreted in terms of dissociative recombination of the molecular ions $\mathrm{Kr}_2^{}{}_{}{}^{+}$ or ${\mathrm{}\left(\mathrm{MXe}\right)\mathrm{}}^{+}$ (where M is an undertermined atom, either Kr or Xe) with subsequent atomic radiation by an excited dissociation product. For Kr, one quantum from various $2p$ to $1s$ transitions appears to be associated with each recombination event. Recombination coefficients of approximately 0.6×${10}^{-6\mathrm{}}$ and 2×${10}^{-6\mathrm{}}$ ${\mathrm{cm}}^3$/electron-sec are obtained for the Kr and Xe recombination process, respectively. These values do not appear to be pressure-dependent. Results of ambipolar diffusion measurements are also stated.