An experimental technique is presented that both minimizes and accounts for the interference background when laser-induced-fluorescence (LIF) measurements are made of NO in lean, high-pressure, premixed, CH4/O2/N2 flames. Measurement interferences such as fluorescence and Raman scattering from secondary species become increasingly important for high-pressure LIF studies. O2 fluorescence interferences are particularly troublesome in lean premixed flames. An excitation–detection scheme that minimizes the effects of these interferences is identified. A procedure that corrects the resulting LIF signal so as to account for any remaining interference signal is then developed. This correction is found to vary from less than 10% of the overall NO signal at atmospheric pressure to over 40% of the overall signal at 14.6 atm for LIF measurements of NO in a series of worst-case flames (φ = 0.6, dilution ratio 2.2). The correction technique is further demonstrated to be portable over a useful range of flame conditions at each pressure.
© 1997 Optical Society of America
D. Douglas Thomsen, F. Frank Kuligowski, and Normand M. Laurendeau, "Background corrections for laser-induced-fluorescence measurements of nitric oxide in lean, high-pressure, premixed methane flames," Appl. Opt. 36, 3244-3252 (1997)