Pressure-broadening and narrowing coefficients and temperature dependence measurements of CO2 at 2.68 μm by laser diode absorption spectroscopy for atmospheric applications

Abstract By using a tunable diode laser absorption spectrometer in conjunction with a cryogenically cooled multipath cell, we have revisited the air-induced pressure-broadening coefficients and the narrowing coefficients related to the Dicke effect, as well as the temperature dependences, for the R(18) and R(20) lines of the (1 0° 1) I  ← (0 0° 0) vibrational band at 2.68 μm of carbon dioxide. The selected transitions are used to probe in situ CO 2 in the troposphere and the lower stratosphere by using balloon-borne laser sensors. The achieved measurements are thoroughly compared to existing former determinations. The impact of processing the in situ atmospheric CO 2 spectra with this new set of molecular data is reported.