2ND-HARMONIC AND SUM-FREQUENCY GENERATION IN AGGASE2 WITH TUNABLE WAVE-GUIDE CO2-LASERS

A tunable source is described, giving extensive coverage of a spectral region around 2000 cm(-1). A frequency self-calibration routine allows for the recording of Doppler-limited absorption profiles with an absolute accuracy of better than 10 MHz. The applicability of the source is demonstrated through measurements on the (CO)-C-12-O-16, (CO)-C-12-O-17 and (CO)-C-12-O-18 isotopomers. Collision-broadening parameters and line strengths are determined, some of the data showing evidence of motional narrowing. Sensitivity limits are determined for linear absorption measurements as well as for photoacoustic absorption, and the feasibility of monitoring all three isotopomers with ppm sensitivity is demonstrated.