THE EFFECTS OF COLLISIONAL QUENCHING ON DEGENERATE 4-WAVE-MIXING

We report a theoretical and experimental investigation of the effects of collisional quenching on resonant degenerate four-wave mixing (DFWM ). Using single-mode laser radiation, peak signal intensity measuremen ts were performed on an isolated line in the A-X transition of NO. By using appropriate mixtures of N2 and CO2 as buffer gases, we varied th e collisional quenching rate over several orders of magnitude while ma intaining a fixed total collisional dephasing rate. The mixtures had a pproximately 100 Torr total pressure and were at room temperature. For I/I(sat) approximately equal to 0.02, DFWM intensities were found to be less affected by variations in quench rate than were laser-induced fluorescence (LIF) intensities (I and I(sat) are the pump laser and on e-photon saturation intensities, respectively). Moreover, for I/I(sat) roughly equal to 0.5, DFWM intensities were observed to be nearly ind ependent of quench rate. The results are compared to two theoretical p redictions, with good agreement observed. Both theories indicate that the minimum sensitivity of DFWM to quenching occurs near I/I(sat) almo st-equal-to 1.