OPTIMIZATION OF A MIDINFRARED HIGH-RESOLUTION DIFFERENCE-FREQUENCY LASER SPECTROMETER

Improved performance of a continuous-wave (cw) laser spectrometer for Doppler-limited infrared spectroscopy of molecules based on difference-frequency generation (DFG) in AgGaS2 has been achieved. The spectrometer was configured to generate continuous scans of up to 1 cm-1 from 1550 to 2100 cm-1. An absolute precision of approximately 6 x 10(-3) cm-1 with a resolution of better than 1.0 MHz (3.3 x 10(-5) cm-1) was achieved. Infrared powers of approximately 20 muW were obtained by employing 90-degrees Type I phase matching in a 45-mm-long AgGaS2 crystal. The high-resolution characteristics of the DFG spectrometer were evaluated by using H2O and N2O spectra. Preliminary infrared kinetic spectroscopy results involving the detection of transient CO radicals from 193-nm acetone photodissociation are also reported.