TIME-RESOLVED LIF OF OH IN THE FLAME FRONT OF PREMIXED AND DIFFUSION FLAMES AT ATMOSPHERIC-PRESSURE

Time-resolved fluorescence measurements are reported for the OH radica l, in the flame fronts of laminar atmospheric pressure flames. Effecti ve (collision-limited) lifetimes were determined following excitation of the A(2) Sigma(+), upsilon' = 0 state of OH using a picosecond dye- laser system based on the distributed-feedback principle. Measurements were made in a premixed knife-edge burner for rich CH4/N2O/N-2 and CH 4/air flames and in a counterflow diffusion burner for a CH4/air flame . In the accessible range, results indicate a net dependence of lifeti me on temperature intermediate between T and T-0.5 for these flames.