Observations of Dicke narrowing and speed dependence in air-broadened CO2 lineshape near 2.06 um
Thinh Q. Bui, David Long, Agata Cygan, Vincent T. Sironneau, Daniel Hogan, Priyanka M. Rapusinghe, Mitchio Okumura
Frequency-stabilized cavity ring-down spectroscopy (FS-CRDS) was used to study CO2 lineshapes in the (20013)←(00001) band centered near 2.06 um. Two rovibrational transitions were chosen for this study to measure non-Voigt collisional effects for air-broadened lines over the pressure range of 7-27 kPa. Lineshape analysis for both lines revealed evidence of simultaneous Dicke (collisional) narrowing and speed-dependent effects, which if not incorporated in the modeling of CO2 lineshapes, introduces biases exceeding 5% in the retrieved air-broadening parameters. As a result, it was observed that the most appropriate line profile for modeling CO2 lineshapes near 2.06 um was the speed-dependent Nelkin-Ghatak profile, which includes both collisional narrowing and speed-dependent effects.
, Long, D.
, Cygan, A.
, Sironneau, V.
, Hogan, D.
, Rapusinghe, P.
and Okumura, M.
Observations of Dicke narrowing and speed dependence in air-broadened CO2 lineshape near 2.06 um, Journal of Chemical Physics, [online], https://doi.org/10.1063/1.4900502
(Accessed December 1, 2023)