Comparison of two-photon excitation schemes for CO detection in flames

Abstract.

Two approaches for CO concentration measurement in premixed and non-premixed hydrocarbon/air flames based on two-photon laser excitation and subsequent detection of induced fluorescence are compared in detail. It is shown that excitation of the C¹ Σ??X¹ Σ ⁺ band of CO indicates significant advantages over the commonly used B¹ Σ??X¹ Σ ⁺ band of the Hopfield–Birge system with respect to crosstalk of simultaneously excited laser-induced fluorescence of C₂. The measurements demonstrate that both approaches give comparable signal intensities and are similarly influenced by multi-photon ionization.