Two-dimensional imaging of molecular hydrogen in H_2–air diffusion flames using two-photon laser-induced fluorescence

We report the use of a tunable ArF laser at 193.26 nm to record simultaneous single-laser-shot, planar images of molecular hydrogen and hot oxygen in a turbulent H(2)-air diffusion flame. Excitation spectra of fuel and oxidantrich flame zones confirm a partial overlap of the two-photon H(2) (6,0) Q(1) E, F ? X and single-photon O(2) (10,2) R(17) B ? X (Schumann-Runge) absorption bands. UV Rayleigh scattering images of flame structure and estimated detection limits for the H(2) two-photon imaging are also presented.