A diode laser sensor has been applied to monitor CO, CO<sub>2</sub>, and CH<sub>4</sub> in combustion gases with absorption spectroscopy and fast extraction-sampling techniques. Survey spectra of the CO 3ν band (R branch) and the 2ν<sub>1</sub> + 2ν<sub>2</sub><sup>0</sup> + ν<sub>3</sub> CO<sub>2</sub> band (R branch) near 6350 cm<sup>−1</sup> and H<sub>2</sub>O lines from the ν<sub>1</sub> + 2ν<sub>2</sub> and 2ν<sub>2</sub> + ν<sub>3</sub> bands in the spectral region from 6345 to 6660 cm<sup>−1</sup> were recorded and compared with calculated spectra (from the HITRAN 96 database) to select optimum transitions for species detection. Species concentrations above a laminar, premixed, methane–air flame were determined from measured absorption in a fast-flow multipass absorption cell containing probe-sampled combustion gases; good agreement was found with calculated chemical equilibrium values.
© 1997 Optical Society of America
Radu M. Mihalcea, Douglas S. Baer, and Ronald K. Hanson, "Diode laser sensor for measurements of CO, CO2, and CH4 in combustion flows," Appl. Opt. 36, 8745-8752 (1997)