A flash-photolysis/laser induced fluorescence spectroscopic study of Rb(5(2)S(1/2)) with CH3Cl and CFCl3 at elevated temperatures

The rate constants for chlorine-atom abstraction reactions of Rb(5(2)S(1/2) ) With CH3Cl (k(1)) and CFCl3 (k(2)) were measured at elevated temperatures (780-830 K) by laser induced fluorescence (LIF) detection of Rb(5(2)S(1/2) ) via the resolved Rydberg transition at lambda = 420.2 nm [Rb(6p(2)P(3/2)) --> Rb(5s(2)S(1/2))]. Rb atoms were generated by pulsed photolysis of RbCl using a customised high pressure Xe flash lamp. The high temperature value s of k(1) and k(2), expressed with an uncertainty of +/- 2 sigma, were (1.2 +/- 0.4) x 10(-12) and (1.6 +/- 0.5) x 10(-12) cm(3) molecule(-1) s(-1), r espectively. The rate constant for the reaction of Rb and CFCl3 constitutes the first value obtained employing LIF as a detection method, as the previ ous measurement reported in the literature, with which it was compared, was performed using atomic resonance absorption spectroscopy. In contrast, the rate constant for Rb + CH3Cl reaction was compared with the foregoing data obtained by FP/LIF technique via the D-line transition [Rb(5p(2)P(3/2)) -- > Rb(5s(2)S(1/2))] at 780 nm and by atomic resonance absorption spectroscop y at 420.2 nm. (C) 1999 Elsevier Science B.V. All rights reserved.