PHOTOCHEMICAL EFFECT IN 2-PHOTON LASER-INDUCED FLUORESCENCE DETECTIONOF CARBON-MONOXIDE IN HYDROCARBON FLAMES

The CO formation as a result of the CO2 photodissociation at 230.08 mn was observed by using the two-photon laser-induced fluorescence (LIF) method. The measurements were performed in a propane-air combustion p roduct flow and in mixtures of CO2 and O-2. The temperature dependence of the fluorescence signal caused by CO molecules, produced in the ph otodissociation of CO2 molecules under the action of laser radiation a t a wavelength of 230.08 nm, was measured at temperatures ranging from 1300 to 2000 K. It is shown that consideration of CO2 photodissociati on under the action of the probing radiation is necessary when one app lies the two-photon LIF method for the measurement of small CO concent rations in high-temperature gas mixtures containing CO2. As an example , a correction is given of the CO concentration profiles measured by t he LIF method in the combustion product flow around a cooled metallic plate. (C) 1998 Optical Society of America. OCIS codes: 120.0120, 120. 1740, 260.5130, 300.2530.