Temperature-Compensated High-Resolution Infrared Absorption Spectroscopy: Application to Carbon Monoxide

The analytic basis of an optical absorption technique suitable for a single line-of-sight determination of average gaseous species number densities in the presence of concentration, pressure and temperature gradients, and particulate loading is presented and applied to carbon monoxide CO. Applying the technique involves using the power of very high-resolution infrared IR spectroscopy, now made available by tunable diode lasers. The method requires the construction of functions of molecular line strengths that are nearly temperature independent. A method of constructing these functions is described and applied to the case of CO. Possible applications to practical combustion systems are also outlined.