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 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.

scholarly journals Validation of a new cavity ring-down spectrometer for measuring tropospheric gaseous hydrogen chloride

2021 ◽  
Author(s):  
Teles C. Furlani ◽  
Patrick R. Veres ◽  
Kathryn E. R. Dawe ◽  
J. Andrew Neuman ◽  
Steven S. Brown ◽  
...  
Keyword(s):  
Response Time ◽  
Hydrogen Chloride ◽  
Limit Of Detection ◽  
Optical Cavity ◽  
Ambient Air ◽  
Detection Methods ◽  
Ambient Atmosphere ◽  
Integration Interval ◽  
Mixing Ratios ◽  
Cavity Ring Down

Abstract. Reliable, sensitive, and widely available hydrogen chloride (HCl) measurements are important for understanding oxidation in many regions of the troposphere. We configured a commercial HCl cavity ring-down spectrometer (CRDS) for sampling HCl in the ambient atmosphere and developed calibration and validation techniques to characterize the measurement uncertainties. The CRDS makes fast, sensitive, and robust measurements of HCl in a high finesse optical cavity coupled to a laser centered at 5739 cm−1. The accuracy was determined to reside between 5–10 %, calculated from laboratory calibrations and an ambient air intercomparison with annular denuders. The precision and limit of detection (3σ) in the 0.5 Hz measurement were below 6 pptv and 18 pptv, respectively for a 30 second integration interval in zero air. The response time of this method is primarily characterized by fitting decay curves to a double exponential equation and is impacted by inlet adsorption/desorption, with these surface effects increasing with RH and decreasing with decreasing HCl mixing ratios. The response time for the tested inlet was 2–6 minutes under the most and least optimal conditions, respectively. An intercomparison with the EPA compendium method for quantification of acidic atmospheric gases showed good agreement, yielding a linear relationship statistically equivalent to unity (slope of 0.97 ± 0.15). The CRDS from this study can detect HCl at atmospherically relevant mixing ratios, often performing comparable or better in sensitivity, selectivity, and response-time from previously reported HCl detection methods.

scholarly journals Validation of a new cavity ring-down spectrometer for measuring tropospheric gaseous hydrogen chloride

2021 ◽  
Vol 14 (8) ◽  
pp. 5859-5871
Author(s):  
Teles C. Furlani ◽  
Patrick R. Veres ◽  
Kathryn E. R. Dawe ◽  
J. Andrew Neuman ◽  
Steven S. Brown ◽  
...  
Keyword(s):  
Response Time ◽  
Hydrogen Chloride ◽  
Limit Of Detection ◽  
Optical Cavity ◽  
Ambient Air ◽  
Detection Methods ◽  
Ambient Atmosphere ◽  
Integration Interval ◽  
Mixing Ratios ◽  
Cavity Ring Down

Abstract. Reliable, sensitive, and widely available hydrogen chloride (HCl) measurements are important for understanding oxidation in many regions of the troposphere. We configured a commercial HCl cavity ring-down spectrometer (CRDS) for sampling HCl in the ambient atmosphere and developed validation techniques to characterize the measurement uncertainties. The CRDS makes fast, sensitive, and robust measurements of HCl in a high-finesse optical cavity coupled to a laser centred at 5739 cm−1. The accuracy was determined to reside between 5 %–10 %, calculated from laboratory and ambient air intercomparisons with annular denuders. The precision and limit of detection (3σ) in the 0.5 Hz measurement were below 6 and 18 pptv, respectively, for a 30 s integration interval in zero air. The response time of this method is primarily characterized by fitting decay curves to a double exponential equation and is impacted by inlet adsorption/desorption, with these surface effects increasing with relative humidity and decreasing with decreasing HCl mixing ratios. The minimum 90 % response time was 10 s and the equilibrated response time for the tested inlet was 2–6 min under the most and least optimal conditions, respectively. An intercomparison with the EPA compendium method for quantification of acidic atmospheric gases showed good agreement, yielding a linear relationship statistically equivalent to unity (slope of 0.97 ± 0.15). The CRDS from this study can detect HCl at atmospherically relevant mixing ratios, often performing comparably or better in sensitivity, selectivity, and response time than previously reported HCl detection methods.

Measurements of Extinction by Aerosol Particles in the Near-Infrared Using Continuous Wave Cavity Ring-Down Spectroscopy

2011 ◽  
Vol 115 (5) ◽  
pp. 774-783 ◽  
Author(s):  
Daniel Mellon ◽  
Simon J. King ◽  
Jin Kim ◽  
Jonathan P. Reid ◽  
Andrew J. Orr-Ewing
Keyword(s):  
Near Infrared ◽  
Continuous Wave ◽  
Aerosol Particles ◽  
Cavity Ring Down Spectroscopy ◽  
Cavity Ring Down

scholarly journals An intercomparison of HO<sub>2</sub> measurements by Fluorescence Assay by Gas Expansion and Cavity Ring–Down Spectroscopy within HIRAC (Highly Instrumented Reactor for Atmospheric Chemistry)

2017 ◽  
Author(s):  
Lavinia Onel ◽  
Alexander Brennan ◽  
Michele Gianella ◽  
Grace Ronnie ◽  
Ana Lawry Aguila ◽  
...  
Keyword(s):  
Water Vapour ◽  
Atmospheric Chemistry ◽  
Total Pressure ◽  
Limit Of Detection ◽  
Fluorescence Assay ◽  
Fluorescence Signal ◽  
Cavity Ring Down Spectroscopy ◽  
Gas Expansion ◽  
Good Agreement ◽  
Cavity Ring Down

Abstract. The HO2 radical was monitored simultaneously using two independent techniques in the Leeds HIRAC atmospheric simulation chamber at room temperature and total pressures of 150 mbar and 1000 mbar of synthetic air. In the first method, HO2 was measured indirectly following sampling through a pinhole expansion to 3 mbar when sampling from 1000 mbar and 1 mbar when sampling from 150 mbar, with subsequent addition of NO to convert it to OH which was detected via laser-induced fluorescence spectroscopy using the FAGE (fluorescence assay by gas expansion) technique. The FAGE method is used widely to measure HO2 concentrations in the field, and was calibrated using the 185 nm photolysis of water vapour in synthetic air with a limit of detection at 1000 mbar of 1.6 × 106 molecule cm−3 for an averaging time of 30 s. In the second method, HO2 was measured directly and absolutely without the need for a calibration using Cavity Ring Down Spectroscopy (CRDS) with the optical path across the entire ~ 1.4 m width of the chamber, with excitation of the first O-H overtone at 1506.43 nm using a diode laser, and with a sensitivity determined from an Allan deviation plot of 3.0 × 108 and 1.5 x 109 molecule cm−3 at 150 mbar and 1000 mbar, respectively, for an averaging period of 30 s. HO2 was generated in HIRAC by the photolysis of Cl2 using black lamps in the presence of methanol in synthetic air and was monitored by FAGE and CRDS for ~ 5–10 minute periods with the lamps on and also during the HO2 decay after the lamps were switched off. At 1000 mbar total pressure the correlation plot of [HO2]FAGE versus [HO2]CRDS gave a gradient of 0.836 ± 0.004 for HO2 concentrations in the range ~ 4–100 × 109 molecule  cm−3 while at 150 mbar total pressure the corresponding gradient was 0.903 ± 0.002 for HO2 concentrations in the range ~ 6–750 × 108 molecule cm−3. For the period after the lamps were switched off, the second-order decay of the HO2 FAGE signal via its self-reaction was used to calculate the FAGE calibration constant for both 150 and 1000 mbar total pressure. This enabled a calibration of the FAGE method at 150 mbar, an independent measurement of the FAGE calibration at 1000 mbar, and an independent determination of the HO2 cross section at 1506.43 nm, σHO2, at both pressures. For CRDS, the HO2 concentration obtained using σHO2 determined using previous reported spectral data for HO2 and the kinetic decay of HO2 method agreed to within 20 and 12 % at 150 and 1000 mbar, respectively. For the FAGE method a very good agreement (difference within 8 %) has been obtained at 1000 mbar between the water vapour calibration method and the kinetic decay of the HO2 fluorescence signal method. This is the first intercomparison for HO2 between FAGE and CRDS methods, and the good agreement between HO2 concentrations measured using the indirect FAGE method and the direct CRDS method provides a validation for the FAGE method, which is used widely for field measurements of HO2 in the atmosphere.

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

&lt;p&gt;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&lt;sub&gt;4, &lt;/sub&gt;CO, SO&lt;sub&gt;2&lt;/sub&gt;, etc) [1]. Due to its very short lifetime (~1 s or less) and very low concentration in the atmosphere (in the order of 10&lt;sup&gt;6&lt;/sup&gt; cm&lt;sup&gt;-&lt;/sup&gt;&lt;sup&gt;3&lt;/sup&gt;), in situ and direct measurement of OH concentration in the atmosphere is challenging [2].&lt;/p&gt;&lt;p&gt;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&lt;sup&gt;12&lt;/sup&gt; OH radicals/cm&lt;sup&gt;3&lt;/sup&gt; 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 &amp;#181;m was employed for probing the Q (1.5e) and Q (1.5f) double-line transitions of the &lt;sup&gt;2&lt;/sup&gt;&amp;#928;&lt;sub&gt;3/2&lt;/sub&gt;&lt;sub&gt;&lt;/sub&gt;state at 3568.52382 and 3568.41693 cm&lt;sup&gt;-&lt;/sup&gt;&lt;sup&gt;1&lt;/sup&gt;, respectively. A 1s detection limit of ~2.7&amp;#215;10&lt;sup&gt;10&lt;/sup&gt; cm&lt;sup&gt;-3&lt;/sup&gt; &amp;#160;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.&lt;/p&gt;&lt;p&gt;The experimental detail and the preliminary results will be presented and discussed.&lt;/p&gt;&lt;p&gt;&lt;strong&gt;&amp;#160;&lt;/strong&gt;&lt;strong&gt;Acknowledgments. &lt;/strong&gt;The authors thank the financial supports from the CPER CLIMIBIO program and the Labex CaPPA project (ANR-10-LABX005).&lt;/p&gt;&lt;p&gt;&lt;strong&gt;References&lt;/strong&gt;&lt;/p&gt;&lt;p&gt;[1]&amp;#160; U. Platt, M. Rateike, W. Junkermann, J. Rudolph, and D. H. Ehhalt, New tropospheric OH measurements, J. Geophys. Res. &lt;strong&gt;93&lt;/strong&gt; (1988) 5159-5166.&lt;/p&gt;&lt;p&gt;[2]&amp;#160; D. E. Heard and M. J. Pilling, Measurement of OH and HO&lt;sub&gt;2&lt;/sub&gt; in the Troposphere, Chem. Rev. &lt;strong&gt;103&lt;/strong&gt; (2003) 5163-5198.&lt;/p&gt;&lt;p&gt;[3]&amp;#160; 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.&lt;/p&gt;&lt;p&gt;[4]&amp;#160; W. Chen, A. A. Kosterev, F. K. Tittel, X. Gao, W. Zhao, &quot;H&lt;sub&gt;2&lt;/sub&gt;S trace concentration measurements using Off-Axis Integrated Cavity Output Spectroscopy in the near-infrared&quot;, Appl. Phys. B 90 (2008) 311-315&lt;/p&gt;&lt;p&gt;[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&lt;/p&gt;

scholarly journals Quantification of peroxynitric acid and peroxyacyl nitrates using an ethane-based thermal dissociation peroxy radical chemical amplification cavity ring-down spectrometer

2018 ◽  
Vol 11 (7) ◽  
pp. 4109-4127
Author(s):  
Youssef M. Taha ◽  
Matthew T. Saowapon ◽  
Faisal V. Assad ◽  
Connie Z. Ye ◽  
Xining Chen ◽  
...  
Keyword(s):  
Limit Of Detection ◽  
Thermal Dissociation ◽  
Peroxy Radical ◽  
Ambient Air ◽  
Oh Radicals ◽  
Ionization Mass ◽  
Chemical Amplification ◽  
Peroxynitric Acid ◽  
Peroxyacyl Nitrates ◽  
Cavity Ring Down

Abstract. Peroxy and peroxyacyl nitrates (PNs and PANs) are important trace gas constituents of the troposphere which are challenging to quantify by differential thermal dissociation with NO2 detection in polluted (i.e., high-NOx) environments. In this paper, a thermal dissociation peroxy radical chemical amplification cavity ring-down spectrometer (TD-PERCA-CRDS) for sensitive and selective quantification of total peroxynitrates (ΣPN  =  ΣRO2NO2) and of total peroxyacyl nitrates (ΣPAN  =  ΣRC(O)O2NO2) is described. The instrument features multiple detection channels to monitor the NO2 background and the ROx ( =  HO2 + RO2 + ΣRO2) radicals generated by TD of ΣPN and/or ΣPAN. Chemical amplification is achieved through the addition of 0.6 ppm NO and 1.6 % C2H6 to the inlet. The instrument's performance was evaluated using peroxynitric acid (PNA) and peroxyacetic or peroxypropionic nitric anhydride (PAN or PPN) as representative examples of ΣPN and ΣPAN, respectively, whose abundances were verified by iodide chemical ionization mass spectrometry (CIMS). The amplification factor or chain length increases with temperature up to 69 ± 5 and decreases with analyte concentration and relative humidity (RH). At inlet temperatures above 120 and 250 °C, respectively, PNA and ΣPAN fully dissociated, though their TD profiles partially overlap. Furthermore, interference from ozone (O3) was observed at temperatures above 150 °C, rationalized by its partial dissociation to O atoms which react with C2H6 to form C2H5 and OH radicals. Quantification of PNA and ΣPAN in laboratory-generated mixtures containing O3 was achieved by simultaneously monitoring the TD-PERCA responses in multiple parallel CRDS channels set to different temperatures in the 60 to 130 °C range. The (1 s, 2σ) limit of detection (LOD) of TD-PERCA-CRDS is 6.8 pptv for PNA and 2.6 pptv for ΣPAN and significantly lower than TD-CRDS without chemical amplification. The feasibility of TD-PERCA-CRDS for ambient air measurements is discussed.

scholarly journals Absorption detection using optical waveguide cavities

2010 ◽  
Vol 88 (5) ◽  
pp. 401-410 ◽  
Author(s):  
Hans-Peter Loock ◽  
Jack A. Barnes ◽  
Gianluca Gagliardi ◽  
Runkai Li ◽  
Richard D. Oleschuk ◽  
...  
Keyword(s):  
Optical Cavity ◽  
Spectroscopic Method ◽  
Optical Loss ◽  
Wavelength Shift ◽  
Cavity Ring Down Spectroscopy ◽  
Mode Spectrum ◽  
Waveguide Cavities ◽  
High Finesse ◽  
Absorption Measurements ◽  
Cavity Ring Down

Cavity ring-down spectroscopy is a spectroscopic method that uses a high quality optical cavity to amplify the optical loss due to the light absorption by a sample. In this presentation we highlight two applications of phase-shift cavity ring-down spectroscopy that are suited for absorption measurements in the condensed phase and make use of waveguide cavities. In the first application, a fiber loop is used as an optical cavity and the sample is introduced in a gap in the loop to allow absorption measurements of nanoliters of solution at the micromolar level. A second application involves silica microspheres as high finesse cavities. Information on the refractive index and absorption of a thin film of ethylene diamine on the surface of the microresonator is obtained simultaneously by the measurements of the wavelength shift of the cavity mode spectrum and the change in optical decay time, respectively.

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