DETECTION OF HF USING INFRARED DEGENERATE 4-WAVE-MIXING

Resonant degenerate four-wave mixing is demonstrated for the detection of HF using both the (1-0) and (3-0) vibrational transitions near 4000 and 11500 cm-1, respectively. The use of rovibrational transitions in DFWM potentially allows the sensitive detection of molecules with otherwise inaccessible electronic states. In addition, high temporal and spatial resolution is obtained by using a pulsed laser with a crossed-beam geometry. High detection sensitivities of > 10(10) molecule/cm3 were achieved using the HF (1-0) transition for resonance enhancement. Detection using the HF (3-0) transition was only possible at pressures greater than almost-equal-to 1 Torr, where the DFWM interaction is dominated by a thermal grating mechanism.