Measurement of radical species concentrations and polycyclic aromatic hydrocarbons in flames by fluorescence and absorption using a tunable dye laser

The development of quantitative laser fluorescence methods for measuring the concentrations of radical species and polycyclic aromatic hydrocarbons (PAH's) in flames was studied. Quantitative laser-saturated fluorescence (LSF) measurements of OH concentration in hydrogen/oxygen/argon flames over wide ranges of flame pressure and stoichiometry were demonstrated. The following measures were undertaken: (1) extent the OH analysis to atmospheric pressure methane-air flames under both clean and sooting conditions; (2) conducted LSF measurements of NH in a subatmospheric methane-nitrous oxide flame; (3) improved the calibration procedure used to obtain number densities from the fluorescence measurements; (4) investigated the effects of nonuniform laser illumination on LSF measurements; (5) detected hydrogen atom fluorescence in a flame using laser-induced two-photon absorption; (6) developed a technique for measuring the concentrations of PAH's in vapor state mixtures; and (7) initiated the application of LSF to measurements of CN.