A Study of the Reaction Li + O2 + M (M = N2, He) over the Temperature Range 267-1100 K by Time-Resolved Laser-Induced Fluorescence of Li(22PJ-22S1/2)

Article abstract of DOI:10.1021/j100324a041

We present an investigation of the recombination reaction between lithium atoms and O2 in the presence of both N2 and He as bath gases.Lithium atoms were produced by the pulsed photolysis of either LiI, LiOH, or LiO2 molecules in the presence of an excess of O2 and the bath gas.The Li atom concentration was then monitored by laser-induced fluorescence of the metal atoms at λ = 670.7 nm using a pulsed nitrogen-pumped dye laser and boxcar integration of the fluorescence signal.Termolecular behavior was demontstrated in the case of both bath gases, and absolute third-order rate constants were obtained over the temperature range 267-1100 K.A fit of these data to the form AT^-n yields k(M = N2) = (4.30 +/- 1.36) * 10_-30(T/300 K)^{-(1.02 +/- 0.06)} cm⁶ molecule^-2 s^-1 and k(M = He) = (1.25 +/- 0.48) * 10^-30(T/300 K)^{-(0.38 +/- 0.08)} cm⁶ molecule^-2 s^-1.It is demontstrated that these measurements are essentially in the low-pressure limit; the rate coefficients are then extrapolated from the experimental temperature range to ambient mesospheric temperatures ( 140 K < T < 240 K) and to flame temperatures (1500 K < T < 2200 K) by means of a satisfactory fit to the Troe formalism.