High-resolution absorption measurements of CO<sub>2</sub> were made in a heated static cell and in the combustion region above a flat-flame burner for the development of an <i>in situ</i> CO<sub>2</sub> combustion diagnostic based on a distributed-feedback diode laser operating near 2.0 μm. Calculated absorption spectra of high-temperature H<sub>2</sub>O and CO<sub>2</sub> were used to find candidate transitions for CO<sub>2</sub> detection, and the <i>R</i>(50) transition at 1.997 μm (the ν<sub>1</sub> + 2ν<sub>2</sub> + ν<sub>3</sub> band) was selected on the basis of its line strength and its isolation from interfering high-temperature water absorption. Measurements of spectroscopic parameters such as the line strength, the self-broadening coefficient, and the line position were made for the <i>R</i>(50) transition, and an improved value for the line strength is reported. The combustion-product populations of CO<sub>2</sub> in the combustion region above a flat-flame burner were determined <i>in situ</i> to verify the measured spectroscopic parameters and to demonstrate the feasibility of the diode-laser sensor.
© 2001 Optical Society of America
Michael E. Webber, Suhong Kim, Scott T. Sanders, Douglas S. Baer, Ronald K. Hanson, and Yuji Ikeda, "In Situ Combustion Measurements of CO2 by Use of a Distributed-Feedback Diode-Laser Sensor Near 2.0 μm," Appl. Opt. 40, 821-828 (2001)