Measurement of OH radicals using off-axis integrated output spectroscopy (OA-ICOS) at 2.8 µm

2021 ◽  
Author(s):  
Minh N. Ngo ◽  
Tong N. Ba ◽  
Denis Petitprez ◽  
Fabrice Cazier ◽  
Weixiong Zhao ◽  
...  
Keyword(s):  
Atmospheric Chemistry ◽  
Near Infrared ◽  
Limit Of Detection ◽  
Optical Cavity ◽  
High Reactivity ◽  
Oh Radicals ◽  
Wavelength Modulation ◽  
Double Line ◽  
Trace Species ◽  
Cavity Output

<p>The hydroxyl (OH) free radical plays an important role in atmospheric chemistry due to its high reactivity with volatile organic compounds (VOCs) and trace species (CH<sub>4, </sub>CO, SO<sub>2</sub>, etc) [1]. Due to its very short lifetime (~1 s or less) and very low concentration in the atmosphere (in the order of 10<sup>6</sup> cm<sup>-</sup><sup>3</sup>), in situ and direct measurement of OH concentration in the atmosphere is challenging [2].</p><p>We report in this paper our recent work on developing a compact spectroscopic instrument based on off-axis integrated cavity output spectroscopy (OA-ICOS) [3] for optical monitoring of OH radicals. In the present work, OH radicals of ~10<sup>12</sup> OH radicals/cm<sup>3</sup> were generated from continue micro-wave discharge at 2.45 GHz of water vapor at low pressure (0.2-1 mbar), and were used as sample for validation of the developed OA-ICOS approaches. Two experimental approaches are designed for the measurements of OH radicals: (1) OA-ICOS [4] and wavelength modulation enhanced OA-ICOS (WM OA-ICOS) [5]. A distributed feedback (DFB) laser operating at 2.8 µm was employed for probing the Q (1.5e) and Q (1.5f) double-line transitions of the <sup>2</sup>Π<sub>3/2</sub><sub></sub>state at 3568.52382 and 3568.41693 cm<sup>-</sup><sup>1</sup>, respectively. A 1s detection limit of ~2.7×10<sup>10</sup> cm<sup>-3</sup>  was obtained for an averaging time of 125 s using a simple OA-ICOS scheme. This limit of detection is further improved by a factor of 3.4 using a WM OA-ICOS approach.</p><p>The experimental detail and the preliminary results will be presented and discussed.</p><p><strong> </strong><strong>Acknowledgments. </strong>The authors thank the financial supports from the CPER CLIMIBIO program and the Labex CaPPA project (ANR-10-LABX005).</p><p><strong>References</strong></p><p>[1]  U. Platt, M. Rateike, W. Junkermann, J. Rudolph, and D. H. Ehhalt, New tropospheric OH measurements, J. Geophys. Res. <strong>93</strong> (1988) 5159-5166.</p><p>[2]  D. E. Heard and M. J. Pilling, Measurement of OH and HO<sub>2</sub> in the Troposphere, Chem. Rev. <strong>103</strong> (2003) 5163-5198.</p><p>[3]  J. B. Paul, L. Lapson, J. G. Anderson, Ultrasensitive absorption spectroscopy with a high-finesse optical cavity and off-axis alignment, Appl. Opt. 40 (2001) 4904-4910.</p><p>[4]  W. Chen, A. A. Kosterev, F. K. Tittel, X. Gao, W. Zhao, "H<sub>2</sub>S trace concentration measurements using Off-Axis Integrated Cavity Output Spectroscopy in the near-infrared", Appl. Phys. B 90 (2008) 311-315</p><p>[5] W. Zhao, X. Gao, W. Chen, W. Zhang, T. Huang, T. Wu, H. Cha, Wavelength modulation off-axis integrated cavity output spectroscopy in the near infrared, Appl. Phys. B 86 (2007) 353-359</p>

scholarly journals A Dual-Laser Sensor Based on Off-Axis Integrated Cavity Output Spectroscopy and Time-Division Multiplexing Method

Sensors ◽  
2020 ◽  
Vol 20 (21) ◽  
pp. 6192
Author(s):  
Kunyang Wang ◽  
Ligang Shao ◽  
Jiajin Chen ◽  
Guishi Wang ◽  
Kun Liu ◽  
...  
Keyword(s):  
Limit Of Detection ◽  
Moving Average ◽  
Optical Cavity ◽  
Ambient Air ◽  
Laser Sensor ◽  
Time Division Multiplexing ◽  
Dual Channel ◽  
Cavity Output ◽  
Time Division ◽  
Dual Laser

In this article, a compact dual-laser sensor based on an off-axis integrated-cavity output spectroscopy and time-division multiplexing method is reported. A complete dual-channel optical structure is developed and integrated on an optical cavity, which allows two distributed feedback (DFB) lasers operating at wavelengths of 1603 nm and 1651 nm to measure the concentration of CO2 and CH4, simultaneously. Performances of the dual-laser sensor are experimentally evaluated by using standard air (with a mixture of CO2 and CH4). The limit of detection (LoD) is 0.271 ppm and 1.743 ppb at a 20 s for CO2 and CH4, respectively, and the noise equivalent absorption sensitivities are 2.68 × 10−10 cm−1 Hz−1/2 and 3.88 × 10−10 cm−1 Hz−1/2, respectively. Together with a commercial instrument, the dual-laser sensor is used to measure CO2 and CH4 concentration over 120 h and verify the regular operation of the sensor for the detection of ambient air. Furthermore, a first-order exponential moving average algorithm is implemented as an effective digital filtering method to estimate the gas concentration.

scholarly journals Cavity ring-down spectroscopy sensor for detection of hydrogen chloride

2013 ◽  
Vol 6 (4) ◽  
pp. 7217-7250
Author(s):  
C. L. Hagen ◽  
B. C. Lee ◽  
I. S. Franka ◽  
J. L. Rath ◽  
T. C. VandenBoer ◽  
...  
Keyword(s):  
Hydrogen Chloride ◽  
Near Infrared ◽  
Limit Of Detection ◽  
Optical Cavity ◽  
High Specificity ◽  
Ionization Mass ◽  
Cavity Ring Down Spectroscopy ◽  
Mist Chamber ◽  
Hcl Concentration ◽  
Cavity Ring Down

Abstract. A laser-based cavity ring-down spectroscopy (CRDS) sensor for measurement of hydrogen chloride (HCl) has been developed and characterized. The instrument uses light from a distributed-feedback diode laser at 1742 nm coupled to a high finesse optical cavity to make sensitive and quantifiable concentration measurements of HCl based on optical absorption. The instrument has a (1σ) limit of detection of < 20 pptv in 1 min and has high specificity to HCl. The measurement response time to changes in input HCl concentration is < 15 s. Validation studies with a previously calibrated permeation tube setup show an accuracy of better than 10%. The CRDS sensor was preliminarily tested in the field with two other HCl instruments (mist chamber and chemical ionization mass spectrometry), all of which were in broad agreement. The mist chamber and CRDS sensors both showed a 400 pptv plume within 50 pptv agreement. The sensor also allows simultaneous sensitive measurements of water and methane, and minimal hardware modification would allow detection of other near-infrared absorbers.

scholarly journals Development and Integration of a CO Detection System Based on Wavelength Modulation Spectroscopy Using Near-Infrared DFB Laser

2018 ◽  
Vol 2018 ◽  
pp. 1-8 ◽  
Author(s):  
Bin Li ◽  
Shuo-Cheng Zhang ◽  
Yao-Dan Chi
Keyword(s):  
Near Infrared ◽  
Limit Of Detection ◽  
Detection System ◽  
Wavelength Modulation Spectroscopy ◽  
Detection Accuracy ◽  
Wavelength Modulation ◽  
Modulation Spectroscopy ◽  
Measure Concentration ◽  
Dfb Laser ◽  
Co Detection

A wavelength modulation spectroscopy- (WMS-) based gas sensing system was established to measure concentration of carbon monoxide (CO) in the range 0–100%. The CO absorption line at 1563.06 nm was scanned with a tunable distributed feedback (DFB) laser, and two InGaAs photodiodes were applied to perform optic-electric conversion. Without using commercial instruments, essential electrical circuits were self-developed and integrated, including laser temperature controller, laser current driver, signal generator, and digital lock-in amplifier. The gas cell deployed in the system was fiber coupled with a total effective optical path length of 50 cm. The second-order harmonic signal was extracted, and experiments of gas detection were carried out to investigate the performance of the sensor, including detection repeatability, detection accuracy, response time, and limit of detection (LoD). Experiment results show that the sensor is reliable and has acceptable probing performance. The maximum relative detection error is less than 3.8%, suggesting good detection stability. Benefiting from the self-developed sensor, the whole CO detection system has small size, affordable expense, and application potential.

scholarly journals Cavity ring-down spectroscopy sensor for detection of hydrogen chloride

2014 ◽  
Vol 7 (2) ◽  
pp. 345-357 ◽  
Author(s):  
C. L. Hagen ◽  
B. C. Lee ◽  
I. S. Franka ◽  
J. L. Rath ◽  
T. C. VandenBoer ◽  
...  
Keyword(s):  
Hydrogen Chloride ◽  
Near Infrared ◽  
Limit Of Detection ◽  
Optical Cavity ◽  
High Specificity ◽  
Ionization Mass ◽  
Cavity Ring Down Spectroscopy ◽  
Mist Chamber ◽  
Hcl Concentration ◽  
Cavity Ring Down

Abstract. A laser-based cavity ring-down spectroscopy (CRDS) sensor for measurement of hydrogen chloride (HCl) has been developed and characterized. The instrument uses light from a distributed-feedback diode laser at 1742 nm coupled to a high finesse optical cavity to make sensitive and quantifiable concentration measurements of HCl based on optical absorption. The instrument has a (1σ) limit of detection of <20 pptv in 1 min and has high specificity to HCl. The measurement response time to changes in input HCl concentration is <15 s. Validation studies with a previously calibrated permeation tube setup show an accuracy of better than 10%. The CRDS sensor was preliminarily tested in the field with two other HCl instruments (mist chamber and chemical ionization mass spectrometry), all of which were in broad agreement. The mist chamber and CRDS sensors both showed a 400 pptv plume within 50 pptv agreement. The sensor also allows simultaneous sensitive measurements of water and methane, and minimal hardware modification would allow detection of other near-infrared absorbers.

A near-infrared C2H2/CH4 dual-gas sensor system combining off-axis integrated-cavity output spectroscopy and frequency-division-multiplexing-based wavelength modulation spectroscopy

The Analyst ◽  
2019 ◽  
Vol 144 (6) ◽  
pp. 2003-2010 ◽  
Author(s):  
Kaiyuan Zheng ◽  
Chuantao Zheng ◽  
Dan Yao ◽  
Lien Hu ◽  
Zidi Liu ◽  
...  
Keyword(s):  
Near Infrared ◽  
High Sensitivity ◽  
Dynamic Measurement ◽  
Wavelength Modulation Spectroscopy ◽  
Wavelength Modulation ◽  
Frequency Division ◽  
Modulation Spectroscopy ◽  
Cavity Output ◽  
High Finesse ◽  
High Finesse Cavity

A near-infrared C2H2/CH4 sensor was demonstrated utilizing a miniaturized high finesse cavity with high sensitivity and remarkable dynamic measurement performance.

scholarly journals Demonstration of a Label-Free and Low-Cost Optical Cavity-Based Biosensor Using Streptavidin and C-Reactive Protein

Biosensors ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 4
Author(s):  
Donggee Rho ◽  
Seunghyun Kim
Keyword(s):  
Limit Of Detection ◽  
Point Of Care ◽  
Low Cost ◽  
Optical Cavity ◽  
Sample Volume ◽  
Small Sample ◽  
Label Free ◽  
C Reactive Protein ◽  
Reactive Protein ◽  
Cavity Structure

An optical cavity-based biosensor (OCB) has been developed for point-of-care (POC) applications. This label-free biosensor employs low-cost components and simple fabrication processes to lower the overall cost while achieving high sensitivity using a differential detection method. To experimentally demonstrate its limit of detection (LOD), we conducted biosensing experiments with streptavidin and C-reactive protein (CRP). The optical cavity structure was optimized further for better sensitivity and easier fluid control. We utilized the polymer swelling property to fine-tune the optical cavity width, which significantly improved the success rate to produce measurable samples. Four different concentrations of streptavidin were tested in triplicate, and the LOD of the OCB was determined to be 1.35 nM. The OCB also successfully detected three different concentrations of human CRP using biotinylated CRP antibody. The LOD for CRP detection was 377 pM. All measurements were done using a small sample volume of 15 µL within 30 min. By reducing the sensing area, improving the functionalization and passivation processes, and increasing the sample volume, the LOD of the OCB are estimated to be reduced further to the femto-molar range. Overall, the demonstrated capability of the OCB in the present work shows great potential to be used as a promising POC biosensor.

Atmospheric Chemistry of CH3CH2OCH3: Kinetics and Mechanism of Reactions with Cl Atoms and OH Radicals

2016 ◽  
Vol 49 (1) ◽  
pp. 10-20 ◽  
Author(s):  
Mads P. Sulbaek Andersen ◽  
Sissel Bjørn Svendsen ◽  
Freja From Østerstrøm ◽  
Ole John Nielsen
Keyword(s):  
Atmospheric Chemistry ◽  
Kinetics And Mechanism ◽  
Oh Radicals ◽  
Cl Atoms

Near-Infrared Off-Axis Integrated Cavity Output Spectroscopic Gas Sensor for Real-Time, In Situ Atmospheric Methane Monitoring

2020 ◽  
pp. 1-1
Author(s):  
Kaiyuan Zheng ◽  
Chuantao Zheng ◽  
Haipeng Zhang ◽  
Junhao Li ◽  
Zidi Liu ◽  
...  
Keyword(s):  
Real Time ◽  
Gas Sensor ◽  
Near Infrared ◽  
Atmospheric Methane ◽  
Cavity Output

scholarly journals High Sensitivity Continuous Monitoring of Chloroform Gas by Using Wavelength Modulation Photoacoustic Spectroscopy in the Near-Infrared Range

2021 ◽  
Vol 11 (15) ◽  
pp. 6992
Author(s):  
Tie Zhang ◽  
Yuxin Xing ◽  
Gaoxuan Wang ◽  
Sailing He
Keyword(s):  
Photoacoustic Spectroscopy ◽  
Continuous Monitoring ◽  
Near Infrared ◽  
Resonant Cavity ◽  
High Sensitivity ◽  
Industrial Applications ◽  
Detection Sensitivity ◽  
Infrared Range ◽  
Wavelength Modulation ◽  
Linear Coefficient

An optical system for gaseous chloroform (CHCl3) detection based on wavelength modulation photoacoustic spectroscopy (WMPAS) is proposed for the first time by using a distributed feedback (DFB) laser with a center wavelength of 1683 nm where chloroform has strong and complex absorption peaks. The WMPAS sensor developed possesses the advantages of having a simple structure, high-sensitivity, and direct measurement. A resonant cavity made of stainless steel with a resonant frequency of 6390 Hz was utilized, and eight microphones were located at the middle of the resonator at uniform intervals to collect the sound signal. All of the devices were integrated into an instrument box for practical applications. The performance of the WMPAS sensor was experimentally demonstrated with the measurement of different concentrations of chloroform from 63 to 625 ppm. A linear coefficient R2 of 0.999 and a detection sensitivity of 0.28 ppm with a time period of 20 s were achieved at room temperature (around 20 °C) and atmosphere pressure. Long-time continuous monitoring for a fixed concentration of chloroform gas was carried out to demonstrate the excellent stability of the system. The performance of the system shows great practical value for the detection of chloroform gas in industrial applications.

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