Optical feedback cavity-enhanced absorption spectroscopy for in situ measurements of the ratio 13C:12C in CO2

Abstract. We present the first comparison of carbon monoxide (CO) measurements performed with a portable laser spectrometer that exploits the optical-feedback cavity-enhanced absorption spectroscopy (OF-CEAS) technique, against a high-performance automated gas chromatograph (GC) with a mercuric oxide reduction gas detector (RGD). First, measurements of atmospheric CO mole fraction were continuously collected in a Paris (France) suburb over 1 week. Both instruments showed an excellent agreement within typically 2 ppb (part per billion in volume), fulfilling the World Meteorological Organization (WMO) recommendation for CO inter-laboratory comparison. The compact size and robustness of the OF-CEAS instrument allowed its operation aboard a small aircraft employed for routine tropospheric air analysis over the French Orléans forest area. Direct OF-CEAS real-time CO measurements in tropospheric air were then compared with later analysis of flask samples by the gas chromatograph. Again, a very good agreement was observed. This work establishes that the OF-CEAS laser spectrometer can run unattended at a very high level of sensitivity ( <  1 ppb) and stability without any periodic calibration.

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Simultaneous Detection of C2H6, CH4 and δ13C-CH4 Using Optical Feedback Cavity Enhanced Absorption Spectroscopy in the Mid-Infrared Region: Towards Application for Dissolved Gas Measurements

10.5194/amt-2018-398-rc2 ◽

2019 ◽

Author(s):

Anonymous

Keyword(s):

Absorption Spectroscopy ◽

Optical Feedback ◽

Simultaneous Detection ◽

Infrared Region ◽

Dissolved Gas ◽

Mid Infrared ◽

Enhanced Absorption ◽

Cavity Enhanced Absorption Spectroscopy ◽

Gas Measurements

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Implementation of an incoherent broadband cavity-enhanced absorption spectroscopy technique in an atmospheric simulation chamber for in situ NO<sub>3</sub> monitoring: characterization and validation for kinetic studies

Atmospheric Measurement Techniques ◽

10.5194/amt-13-6311-2020 ◽

2020 ◽

Vol 13 (11) ◽

pp. 6311-6323 ◽

Cited By ~ 1

Author(s):

Axel Fouqueau ◽

Manuela Cirtog ◽

Mathieu Cazaunau ◽

Edouard Pangui ◽

Pascal Zapf ◽

...

Keyword(s):

Absorption Spectroscopy ◽

Rate Constants ◽

Optical Cavity ◽

In Situ Monitoring ◽

Effective Length ◽

Integration Time ◽

Enhanced Absorption ◽

Cavity Enhanced Absorption Spectroscopy ◽

Simulation Chamber

Abstract. An incoherent broadband cavity-enhanced absorption spectroscopy (IBBCEAS) technique has been developed for the in situ monitoring of NO3 radicals at the parts per trillion level in the CSA simulation chamber (at LISA). The technique couples an incoherent broadband light source centered at 662 nm with a high-finesse optical cavity made of two highly reflecting mirrors. The optical cavity which has an effective length of 82 cm allows for up to 3 km of effective absorption and a high sensitivity for NO3 detection (up to 6 ppt for an integration time of 10 s). This technique also allows for NO2 monitoring (up to 9 ppb for an integration time of 10 s). Here, we present the experimental setup as well as tests for its characterization and validation. The validation tests include an intercomparison with another independent technique (Fourier-transform infrared, FTIR) and the absolute rate determination for the reaction trans-2-butene + NO3, which is already well documented in the literature. The value of (4.13 ± 0.45) × 10−13 cm3 molecule−1 s−1 has been found, which is in good agreement with previous determinations. From these experiments, optimal operation conditions are proposed. The technique is now fully operational and can be used to determine rate constants for fast reactions involving complex volatile organic compounds (VOCs; with rate constants up to 10−10 cm3 molecule−1 s−1).

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