Highly Sensitive Tunable Diode Laser Absorption Spectroscopy of CO2 Around 1.31 μm

The absolute absorption spectrum intensities of carbon dioxide samples has been recorded with a tunable diode laser spectrometer in the spectral range 6350–6364 cm−1, which is suitable for the in-situ sensing of carbon dioxide in the lower stratosphere studied using a commercial telecommunication-type diode laser. It was found that the typical uncertainty of experimental line intensities is about 1% compared with the values listed in the HITRAN database, which are calculated by direct numerical diagonalization. The intensity of the weakest line we detected in this experiment is 1.116×10−26 cm−1/(molecule.cm−2) at the pressure of 0.5 Torr, and the corresponding absorption is 3.2×10−6 with SNR of 4.53.