ION RECOMBINATION RATES IN RARE-GAS CATION HALIDE ANION SYSTEMS .2. KRF-STAR AND XECL-STAR

The emission spectroscopy/pulse radiolysis method of determining three-body ionic recombination rate constants in rare-gas-halogen source gas mixtures has been extended to systems where the emission is produced by both ionic and nonionic pathways. This has enabled recombination coefficient measurements to be done over a large pressure range for irradiated Kr/SF6 and Xe/CFCl3 gas mixtures. The rate constants measured for both these systems show the typical pressure dependence of an increase to a maximum value of approximately 2.5 x 10(15) M-1 s-1 (approximately 4 x 10(-6) cm3 s-1), before the onset of the diffusion-controlled reaction. These values have been compared to the predictions of the Langevin-Harper diffusion-controlled and the Bates termolecular recombination models. The large discrepancies between theory and experiment have shown that other recombination processes dominate the ionic recombination.