Kinetic measurements of fluorine, bromine and iodine atom-abstraction reactions at elevated temperatures by ground-state atomic rubidium, Rb(5 2S 1/2), studied by time-resolved laser-induced fluorescence

Abstract

The kinetics of a range of halogen atom-abstraction reactions undergone by atomic rubidium in its electronic ground state, Rb(5 2S 1/2), have been investigated by time-resolved laser-induced fluorescence at elevated temperatures. Rb(5 2S 1/2) was generated in an excess of halogenated reactant and He buffer gas by pulsed photolysis of rubidium halide vapours. Two separate experimental systems were employed operating at the Rydberg transition at λ=420.2 nm {Rb[6p( 2P 3/2)]→Rb[5s( 2S 1/2)]} and at the shorter wavelength component of the spin-orbit resolved D-line doublet transition at λ=780.0 nm {Rb[5s5p( 2P 3/2)]→Rb[5s( 2S 1/2)]}. Second-order rate constants k RX for various F, Br and I abstraction reactions have been measured for essentially single-temperature conditions. These rate constants, which represent a new body of absolute rate data for Rb( 2S 1/2), are compared with the values reported hitherto by time-resolved atomic resonance absorption spectroscopy and with those previously obtained for other alkali metal atoms using time-resolved techniques.