Knowledge Bank

Temperature measurements have been made in the burnt gas region of $CH4/N2O$ flames by four spectroscopic techniques. First, laser excited fluorescence (LEF) measurements in the $A2\Sigma +\to x2\pi (1,1)$ band of $OH1$ were obtained by scanning a frequency doubled flashlamp pumped by laser Over the $R1$ and $R2$ branches. Fluorescence was detected by a monochromator set for 33 {\AA} bandpass centered at 3175 {\AA}. The temperature is derived from the rotational distribution in the v=1 State of $X2\pi$. The next two technique incorporated a slot burner placed inside a cw argon ion laser Cavity. A double monochromator with associated electronics was used to obtain Raman spectra of $N2$ in the flame. Both the Stokes Q branch ro-vib spectra and the anti-Stokes pure rotational Spectra were recorded. From these measurements vibration and rotational temperatures were Determined. The forth method used was line reversal applied to the R branch of the OH (0,0) band at 3064 {\AA}. The LEF, vibrational Raman, and Oh banc reversal measurements are in excellent Agreement at 2200k for the stoichiometric $CH4/N2O$ flame. The rotational Raman temperature is lower, but within error limits. Comparisons of the techniques will be presented.