TIME-RESOLVED LASER-INDUCED FLUORESCENCE SPECTROSCOPIC STUDIES OF RB(5(2)S(1 2)) WITH N2O AT ELEVATED-TEMPERATURES/

We present a kinetic study of the oxidation reaction of Rb(5(2)S(1/2)) with N2O at elevated temperatures by the technique of pulsed photolys is of a Rb atom precursor, RbCl, followed by time-resolved laser-induc ed fluorescence spectroscopy of Rb atoms using the resolved Rydberg tr ansition at lambda = 420.2 nm (Rb(6(2)P(3/2)) --> Rb(5(2)S(1/2))) A va lue of the absolute second-order rate constant of (2.1 +/- 0.4) x 10(- 11) cm(3) molecule-1 s(-1) has been obtained at 830 K. This result is compared with the previously reported result obtained by atomic resona nce absorption spectroscopy. An estimate of the diffusion coefficient for rubidium in helium of D-12(Rb-He) = (0.27 +/- 0.03) cm(2) s(-1) at s.t.p. is reported. Finally, the result is considered briefly in term s of the potential surfaces involved in the reaction. Rb(5(2)S(1/2)) N2O(X-1 Sigma(+)) correlates directly with the ground state products RbO(X-2 Sigma(+)) + N-2(X-1 Sigma(+)g) via a (2)A' surface. We believe the present type of investigation to constitute the first study of th e present process by flash photolysis with laser-induced fluorescence (LIF). (C) 1997 Elsevier Science B.V.