ABSOLUTE FLUORESCENCE YIELDS FROM ELECTRON-IRRADIATED GASES .2. KRF-ASTERISK AND XEF-ASTERISK

Absolute total fluorescence yields for the KrF(B,C) and XeF*(B,C) sta tes have been determined from pulse-electron-irradiated Kr/SF6 and Xe/ SF6 gas mixtures. By application of established formation and quenchin g mechanisms and rate constants, the KrF yield has been resolved into its two constituent components, corresponding to exciplex formation b y excited-state reaction of Kr species and ionic recombination. The in itial yield of electronically excited krypton atoms that can react wit h SF6, Kr + SF6 --> KrF* + products, was determined to be G(0)* = 0.7 0 +/- 0.10, while the corresponding three-body ionic recombination rea ction, Kr-2(+) + SF6- + Kr --> KrF + products, gave G(0)(+) = 1.70 +/ - 0.10. Analogous studies of the XeF emission showed that ionic recom bination is essentially the only formation pathway, with a calculated initial fluorescence yield for the reaction Xe-2(+) + SF6- + Xe --> Xe F + products of G(0)(+) = 0.26 +/- 0.02. The experimental values are compared to the predictions of current theoretical models, and the imp ortance of alternative reaction pathways is discussed.