Observations of Dicke narrowing and speed dependence in air-broadened CO_2 lineshapes near 2.06 μm
Abstract
Frequency-stabilized cavity ring-down spectroscopy was used to study CO_2 lineshapes in the (20013) ← (00001) band centered near 2.06 μm. Two rovibrational transitions were chosen for this study to measure non-Voigt collisional effects for air-broadened lines over the pressure range of 7 kPa–28 kPa. Lineshape analysis for both lines revealed evidence of simultaneous Dicke (collisional) narrowing and speed-dependent effects that would introduce biases exceeding 2% in the retrieved air-broadening parameters if not incorporated in the modeling of CO_2 lineshapes. Additionally, correlations between velocity- and phase/state changing collisions greatly reduced the observed Dicke narrowing effect. As a result, it was concluded that the most appropriate line profile for modeling CO_2 lineshapes near 2.06 μm was the correlated speed-dependent Nelkin-Ghatak profile, which includes all of the physical effects mentioned above and leads to a consistent set of line shape parameters that are linear with gas pressure.
Additional Information
© 2014 AIP Publishing LLC. Received 11 August 2014. Accepted 15 October 2014. Published online 03 November 2014. This work was supported by the Orbiting Carbon Observatory-2 (OCO-2) project at the Jet Propulsion Laboratory under contract with the National Aeronautics and Space Administration (NASA) through the NASA grant NAS7-03001. T.Q.B. was supported by a NASA Earth and Space Sciences Fellowship and the NASA Mars Fundamental Research Grant NNX12AI01G. D.W.H. was supported by the Jack and Edith Roberts Summer Undergraduate Research Fellowship. Support for D.A.L. and V.T.S. was provided by the NIST Greenhouse Gas Measurements and Climate Research Program. A.C., D.L., and R.C. were partially supported by the Foundation for Polish Science TEAM Project co-financed by the EU European Regional Development Fund, the National Science Centre, Project Nos. DEC-2011/01/B/ST2/00491 and UMO-2013/11/D/ST2/02663, and is part of the program of the national laboratory FAMO in Toruń, Poland. A.C. was further supported by the Foundation for Polish Science START Project.Attached Files
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Additional details
- Alternative title
- Observations of Dicke narrowing and speed dependence in air-broadened CO2 lineshapes near 2.06 μm
- Eprint ID
- 51531
- Resolver ID
- CaltechAUTHORS:20141110-151611075
- NASA/JPL
- NAS7-03001
- NASA
- NNX12AI01G
- NASA
- Jack and Edith Roberts Summer Undergraduate Research Fellowship
- National Institute of Standards and Technology (NIST)
- Foundation for Polish Science
- DEC-2011/01/B/ST2/00491
- National Science Centre (Poland)
- UMO-2013/11/D/ST2/02663
- National Science Centre (Poland)
- European Regional Development Fund
- Caltech Summer Undergraduate Research Fellowship (SURF)
- Created
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2014-11-11Created from EPrint's datestamp field
- Updated
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2021-11-10Created from EPrint's last_modified field