The use of mid-infrared polarization spectroscopy (PS) for the detection of CO2 has been demonstrated. The P(13) and P(14) resonances of the (0 00 0)→(1 00 1) transition of CO2 were probed using a single-mode optical parametric generator system to produce a high-intensity laser beam at approximately 2.7 μm. The experiments were performed in an atmospheric pressure CO2 jet and also in a sub-atmospheric pressure gas cell. The experimental results were compared with the results of the time-dependent density-matrix equations using direct numerical integration. The Zeeman-state structure of the upper and lower energy levels was included in the multi-state formulation of the density-matrix equations. Fifty-eight Zeeman states and two bath levels were included in the numerical analysis of the P(14) transition. The measured and calculated PS line shapes were in good agreement, and the absolute experimental signal level agreed with the theoretical calculation to within a factor of five.
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