Open-path trace gas detection of ammonia based on cavity-enhanced absorption spectroscopy

Abstract. Cavity enhanced methods in absorption spectroscopy have seen a considerable increase in popularity during the past decade. Especially Cavity Enhanced Absorption Spectroscopy (CEAS) established itself in atmospheric trace gas detection by providing tens of kilometers of effective light path length using a cavity as short as 1 m. In this paper we report on the construction and testing of a compact and power efficient light emitting diode based broadband Cavity Enhanced Differential Optical Absorption Spectrometer (CE-DOAS) for in situ field observation of atmospheric NO3. This device combines the small size of the cavity with the enormous advantages of the DOAS approach in terms of sensitivity and specificity. In particular, no selective removal of the analyte (here NO3) is necessary, thus the CE-DOAS technique can – in principle – measure any gas detectable by DOAS. We will discuss the advantages of using a light emitting diode (LED) as light source particularly the precautions which have to be satisfied for the use of LEDs. The instrument was tested in the lab by detecting NO3 in a mixture of NO2 and O3 in air. It was then compared to other trace gas detection techniques in an intercomparison campaign in the atmosphere simulation chamber SAPHIR at NO3 concentrations as low as 6.3 ppt.

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Comparison of nitrous acid detection using open-path incoherent broadband cavity-enhanced absorption spectroscopy and extractive long-path absorption photometry

10.5194/amt-2021-291 ◽

2021 ◽

Author(s):

Sophie Dixneuf ◽

Albert A. Ruth ◽

Rolf Häseler ◽

Theo Brauers ◽

Franz Rohrer ◽

...

Keyword(s):

Absorption Spectroscopy ◽

Nitrous Acid ◽

Hot Spot ◽

Integration Time ◽

Mixing Ratios ◽

Enhanced Absorption ◽

Cavity Enhanced Absorption Spectroscopy ◽

Open Path ◽

Ccd Detector ◽

No2 Detection

Abstract. An instrument based on 20 m open-path incoherent broadband cavity-enhanced absorption spectroscopy (IBBCEAS) was established at the Jülich SAPHIR chamber in Spring 2011. The setup was optimized for the detection of HONO and NO2 in the near UV region 352–386 nm, utilizing a bright hot-spot Xe-arc lamp and a UV-enhanced CCD detector. A 2σ detection limit of 26 pptv for HONO and 76 pptv for NO2 was achieved for an integration time of 1 min. Methacrolein has also been detected at mixing ratios below 5 ppbv. The IBBCEAS instrument’s performance for HONO and NO2 detection was compared to that of extractive wet techniques, long-path absorption photometry (LOPAP) and chemiluminescence spectrometry (CLS) NOx detection, respectively.

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Mobile system for open-path trace gas detection in the mid-infrared using a Raman-shifted Cr:LiSAF source

10.1117/12.366427 ◽

1999 ◽

Author(s):

Paula R. Wamsley ◽

Carl S. Weimer ◽

Jeffrey T. Applegate ◽

Stuart P. Beaton ◽

Brian S. Beyer

Keyword(s):

Gas Detection ◽

Trace Gas ◽

Mobile System ◽

Trace Gas Detection ◽

Mid Infrared ◽

Open Path

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Monitoring Ambient Nitrate Radical by Open Path Cavity Enhanced Absorption Spectroscopy

10.5194/egusphere-egu2020-18725 ◽

2020 ◽

Author(s):

Haichao Wang ◽

Keding Lu

Keyword(s):

Absorption Spectroscopy ◽

Field Application ◽

Nitrate Radical ◽

Absorption Length ◽

Enhanced Absorption ◽

Cavity Enhanced Absorption Spectroscopy ◽

Open Path ◽

Sampling Line ◽

Forest Region ◽

Reactive Trace Gases

We described an open-path cavity enhanced absorption spectroscopy (OP-CEAS) technique for ambient measurement of nitrate radical (NO3) near 662 nm. Compared with the close type CEAS system with a sampling line, the OP-CEAS is featured with high accuracy due to free of quantifying NO3 loss in the sampling line and cavity. Based on a 0.84 m long open path cavity, the effective absorption length of ~5 kilometers is achieved by a coupled high reflectivity mirrors with the reflectivity of 0.99985 at 662 nm. The detection limit of OP-CEAS for NO3 measurement is 3.0 pptv (2&#963;) in 30 seconds. The uncertainty is 11.2% and dominated by the cross section of NO3. The instrument was successfully applied in a field measurement at low particulate matter (PM) loading condition. As the sensitive would be decreased due to the strong PM extinctions under heavy PM pollution condition, we highlight the feasibility of this OP-CEAS configuration in the field application under the low PM condition, such as the forest region affected by anthropogenic emissions. This technique also appropriates to be expended in the field detection of other reactive trace gases in future studies.

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Mid-Infrared Tunable Laser-Based Broadband Fingerprint Absorption Spectroscopy for Trace Gas Sensing: A Review

Applied Sciences ◽

10.3390/app9020338 ◽

2019 ◽

Vol 9 (2) ◽

pp. 338 ◽

Cited By ~ 16

Author(s):

Zhenhui Du ◽

Shuai Zhang ◽

Jinyi Li ◽

Nan Gao ◽

Kebin Tong

Keyword(s):

Absorption Spectroscopy ◽

Gas Sensing ◽

Tunable Laser ◽

Gas Detection ◽

Trace Gas ◽

Spectroscopic Techniques ◽

Trace Gas Detection ◽

Absorption Bands ◽

Mid Infrared ◽

Broadband Absorption

The vast majority of gaseous chemical substances exhibit fundamental rovibrational absorption bands in the mid-infrared spectral region (2.5–25 μm), and the absorption of light by these fundamental bands provides a nearly universal means for their detection. A main feature of optical techniques is the non-intrusive in situ detection of trace gases. We reviewed primarily mid-infrared tunable laser-based broadband absorption spectroscopy for trace gas detection, focusing on 2008–2018. The scope of this paper is to discuss recent developments of system configuration, tunable lasers, detectors, broadband spectroscopic techniques, and their applications for sensitive, selective, and quantitative trace gas detection.

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