Kr+ laser excitation of NH2 in atmospheric pressure flames

Fluorescence in the A 2A1−X 2B1 system of the NH2 radical has been excited in NH3/N2O/N2, H2/N2O/N2, and CH4/N2O/N2 flames using the 6471 A line of a krypton ion laser. Rotationally resolved fluorescence spectra indicate that the laser simultaneously pumps two rotational lines in the (0,11,0)–(0,2,0)∑ vibrational hot band of the radical. The placement of the laser line relative to the two molecular transitions has been inferred from intensities in the fluroescence spectrum. Rotational and vibrational energy transfer in the excited state were observed to be very slow in comparison to electronic quenching by the flame molecules. An NH2 density profile in a rich H2/N2O/N2 flame is given. Also, a method for the calculation of Einstein coefficients and oscillator strengths for nonperturbed, main‐branch transitions is presented.