Spatially resolved vibrational temperature profiles in flames from molecular absorption spectroscopy

A highly collimated laser beam is used to observe molecular absorption in a premixed air-acetylene flame by providing a two-dimensional image on a vidicon camera. Spatially resolved molecular concentrations can thus be obtained in 1/60 second. By measurement of the relative intensities of absorption from different vibrational levels in the ground state of the molecules, a vibrational temperature can be derived for each of the spatial regions in the flame. This information is directly relevant to the understanding of dissociation in flames