Stimulated emission pumping of OH and NH in flames by using two-color resonant four-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, substantial signal-to-noise ratios in the (0-0) A(2) Sigma(+)-X(2)II system of OH are achieved. The high sensitivity is applied to perform stimulated emission pumping involving the weak (0-1) vibrational band. In addition, we demonstrate that the technique is sensitive to state changing collisions.