Near-infrared cavity ringdown spectroscopy of water vapor in an atmospheric flame

We have used cavity ringdown spectroscopy (CRDS) to measure near-infrared overtone transitions of water in atmospheric flames (propane premixed jet and laminar methane-air flat flame burner). The strong signal output with a well-defined laser beam direction and the insensitivity to strong background emission present in hostile environments make CRDS ideal for the study of combustion environments. We have obtained spectra of water vapor from within a flame and extracted a profile of the rotational temperature and concentration of water vapor as a function of distance from the plane burner surface.