Determination of N-atom concentrations in low-pressure premixed H2/O2/N2 flames doped with NH3, HCN and (CN)2

Lawitzki A, Bittner J, Kohse-Höinghaus K. Determination of N-atom concentrations in low-pressure premixed H2/O2/N2 flames doped with NH3, HCN and (CN)2. Chemical Physics Letters. 1990;175(5):429-433.Spatially resolved N-atom concentration and temperature profiles were measured in several stoichiometric, flat, premixed, low-pressure H2/O2/N2 flames doped with small amounts of N-containing fuels. Temperature was obtained from OH (A 2[Sigma]+ -X 2[Pi], 1-0) excitation spectra. N atoms were detected by two-photon laser-induced fluorescence, exciting the 3p4 D o 7/2 state near 211nm and monitoring the (3p 4D o-3s4 P) transition near 870 nm. N-atom concentrations were determined with the aid of a calibration technique using known atom concentrations in a discharge flow reactor and previously determined quenching coefficients. In the flames, peak N-atom mole fractions ranged from about 3 to 90 ppm