AI Article Synopsis
- A rate-equation model has been created to simulate laser-induced fluorescence of carbon monoxide (CO) in a specific wavelength band, with results compared to experimental data from various laser pulse types.
- The model showed that at low laser power, CO fluorescence signals are quadratically related to laser intensity, but change to sublinear relationships at higher intensities due to photoionization effects.
- Additionally, simulations indicate that the most effective CO signal occurs with a transform-limited femtosecond pulse that can adequately cover the necessary absorption spectrum, making this model useful for studying other combustion species as well.
Article Abstract
A model based on rate-equation analysis has been developed for simulation of two-photon-excited laser-induced fluorescence of carbon monoxide (CO) in the Hopfield-Birge band at 230 nm. The model has been compared with experimental fluorescence profiles measured along focused beams provided by lasers emitting nano-, pico-, and femtosecond pulses. Good quantitative agreement was obtained between simulations and experimental data obtained in premixed CH/CH-air flames. For excitation with femtosecond pulses, experimental and simulated fluorescence signals showed quadratic dependence on laser power under conditions of low laser irradiance, whereas different sublinear dependencies were obtained at higher irradiances due to photoionization. Simulations of CO signal versus femtosecond laser linewidth suggest the strongest signal for a transform-limited pulse, which is sufficiently broad spectrally to cover the CO Q-branch absorption spectrum. Altogether, the developed rate-equation model allows for analysis of two-photon excitation fluorescence to arrange suitable diagnostic configurations and retrieve quantitative data for CO as well as other species in combustion, such as atomic oxygen and hydrogen.
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| http://dx.doi.org/10.1364/OE.27.025656 | DOI Listing |
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