STIMULATED-EMISSION PUMPING OF OH AND NH IN FLAMES BY USING 2-COLOR RESONANT 4-WAVE-MIXING

In this work we examine the analytical potential of two-color resonant four-wave mixing for the determination and characterization of trace elements in a combustion environment. Experimental results for NH and OH in flames at atmospheric pressure are presented. The selectivity of the technique is used to simplify the Q-branch region of the (0-0) A( 3)II-X (3) Sigma(-) vibronic transition of NH. Furthermore, substantia l signal-to-noise ratios in the (0-0) A(2) Sigma(+)-X(2)II system of O H are achieved. The high sensitivity is applied to perform stimulated emission pumping involving the weak (0-1) vibrational band. In additio n, we demonstrate that the technique is sensitive to state changing co llisions.