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Wang L, Wang Y, Yang G, Li Y, Liu Y, Lu Y, Yao L, Wang L. Measurements of Atmospheric HO 2 Radicals Using Br-CIMS with Elimination of Potential Interferences from Ambient Peroxynitric Acid. Anal Chem 2024. [PMID: 39151028 DOI: 10.1021/acs.analchem.4c01184] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/18/2024]
Abstract
As a promising direct measurement method of atmospheric hydroperoxyl radicals (HO2), bromide chemical ionization mass spectrometry (Br-CIMS) has been first demonstrated by Sanchez et al. (Atmos. Meas. Tech. 2016, 9, 3851-3861). However, field application of this method is currently still sparse, and there is still a gap between measured HO2 concentrations and calculated ones derived from the atmospheric equilibrium between HO2 and peroxynitric acid (HO2NO2). In this work, we constructed an improved Br-CIMS with optimizations of custom-built front-end devices, chamber pressures, and instrumental voltages to achieve a 3σ detection limit of 0.5 ppt at an integration time of 60 s and a sensitivity of 1-3 cps ppt-1 under a total reagent ion signal of 0.2 MHz for HO2 detection. HO2NO2, a product from atmospheric reactions between HO2 and NO2, can also be detected by Br-CIMS, whose interference on the HO2 measurement was found but nearly eliminated by regulating key CIMS voltages to minimize the decomposition of (BrHO2NO2)- ions in the MS. In addition, a 2 week field campaign was carried out in urban Shanghai, demonstrating that the interference of HO2 from ambient HO2NO2 was less than 10% of the true HO2 signal under our optimized CIMS voltage setting. Our study suggests that Br-CIMS is a reliable technique for atmospheric HO2 measurements.
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Affiliation(s)
- Lihong Wang
- Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention (LAP3), Department of Environmental Science & Engineering, Jiangwan Campus, Fudan University, Shanghai 200438, China
| | - Yuwei Wang
- Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention (LAP3), Department of Environmental Science & Engineering, Jiangwan Campus, Fudan University, Shanghai 200438, China
| | - Gan Yang
- Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention (LAP3), Department of Environmental Science & Engineering, Jiangwan Campus, Fudan University, Shanghai 200438, China
| | - Yueyang Li
- Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention (LAP3), Department of Environmental Science & Engineering, Jiangwan Campus, Fudan University, Shanghai 200438, China
| | - Yiliang Liu
- Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention (LAP3), Department of Environmental Science & Engineering, Jiangwan Campus, Fudan University, Shanghai 200438, China
| | - Yiqun Lu
- Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention (LAP3), Department of Environmental Science & Engineering, Jiangwan Campus, Fudan University, Shanghai 200438, China
| | - Lei Yao
- Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention (LAP3), Department of Environmental Science & Engineering, Jiangwan Campus, Fudan University, Shanghai 200438, China
- Shanghai Institute of Pollution Control and Ecological Security, Shanghai 200092, China
- National Observations and Research Station for Wetland Ecosystems of the Yangtze Estuary, Shanghai 200438, China
| | - Lin Wang
- Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention (LAP3), Department of Environmental Science & Engineering, Jiangwan Campus, Fudan University, Shanghai 200438, China
- Shanghai Institute of Pollution Control and Ecological Security, Shanghai 200092, China
- National Observations and Research Station for Wetland Ecosystems of the Yangtze Estuary, Shanghai 200438, China
- Collaborative Innovation Center of Climate Change, Nanjing 210023, China
- IRDR International Center of Excellence on Risk Interconnectivity and Governance on Weather/Climate Extremes Impact and Public Health, Fudan University, Shanghai 200438, China
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2
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Pasik D, Iyer S, Myllys N. Cost-effective approach for atmospheric accretion reactions: a case of peroxy radical addition to isoprene. Phys Chem Chem Phys 2024; 26:2560-2567. [PMID: 38170853 DOI: 10.1039/d3cp04308h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2024]
Abstract
We present an accurate and cost-effective method for investigating the accretion reactions between unsaturated hydrocarbons and oxidized organic radicals. We use accretion between isoprene and primary, secondary and tertiary alkyl peroxy radicals as model reactions. We show that a systematic semiempirical transition state search can lead to better transition state structures than relaxed scanning with density functional theory with a significant gain in computational efficiency. Additionally, we suggest accurate and effective quantum chemical methods to study accretion reactions between large unsaturated hydrocarbons and oxidized organic radicals. Furthermore, we examine the atmospheric relevance of these types of reactions by calculating the bimolecular reaction rate coefficients and formation rates under atmospheric conditions from the quantum chemical reaction energy barriers.
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Affiliation(s)
- Dominika Pasik
- Department of Chemistry, University of Helsinki, Helsinki 00014, Finland.
- Institute for Atmospheric and Earth System Research, University of Helsinki, Helsinki 00014, Finland
| | - Siddharth Iyer
- Aerosol Physics Laboratory, Tampere University, Tampere FI-3720, Finland
| | - Nanna Myllys
- Department of Chemistry, University of Helsinki, Helsinki 00014, Finland.
- Institute for Atmospheric and Earth System Research, University of Helsinki, Helsinki 00014, Finland
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3
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Zhou J, Zhao W, Zhang Y, Fang B, Cheng F, Xu X, Ni S, Zhang W, Ye C, Chen W, Venables DS. Amplitude-Modulated Cavity-Enhanced Absorption Spectroscopy with Phase-Sensitive Detection: A New Approach Applied to the Fast and Sensitive Detection of NO 2. Anal Chem 2022; 94:3368-3375. [PMID: 35143171 DOI: 10.1021/acs.analchem.1c05484] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Accurate and sensitive measurements of NO2 play an extremely important role in atmospheric studies. Increasingly, studies require NO2 measurements with parts per trillion by volume (pptv-level) detection limits. Other desirable instrument attributes include ease of use, long-term stability, and low maintenance. In this work, we report the development of an amplitude-modulated multimode-diode-laser-based cavity-enhanced absorption spectroscopy (AM-CEAS) system operating at 406 nm that uses phase-sensitive detection for extremely sensitive NO2 detection. The laser was TTL-modulated at 35 kHz. The mirror reflectivity was determined to be 99.985% based on the ring-down time measurement. The cavity base length was 47.5 cm, giving an effective absorption pathlength of ∼3.26 km. AM-CEAS achieved a 1σ detection precision of 35 pptv in a 1 s data acquisition time (4.98 × 10-10 cm-1), over 4 times lower than that attained using a ring-down approach and the same optical system. The AM-CEAS precision improved to 8 pptv over a data acquisition time of 30 s (1.14 × 10-10 cm-1). The AM-CEAS method with the multimode diode laser integrates the advantages of high light injection efficiency like on-axis alignment cavity ring-down spectroscopy, low cavity-mode noise like off-axis alignment CEAS, and narrow-bandwidth high-sensitivity weak signal detection of modulation spectroscopy, providing a powerful, straightforward, and general method for ultrasensitive absorption and extinction measurements.
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Affiliation(s)
- Jiacheng Zhou
- Laboratory of Atmospheric Physico-Chemistry, Anhui Institute of Optics and Fine Mechanics, HFIPS, Chinese Academy of Sciences, Hefei, 230031 Anhui, China.,University of Science and Technology of China, Hefei, 230026 Anhui, China
| | - Weixiong Zhao
- Laboratory of Atmospheric Physico-Chemistry, Anhui Institute of Optics and Fine Mechanics, HFIPS, Chinese Academy of Sciences, Hefei, 230031 Anhui, China
| | - Yang Zhang
- Laboratory of Atmospheric Physico-Chemistry, Anhui Institute of Optics and Fine Mechanics, HFIPS, Chinese Academy of Sciences, Hefei, 230031 Anhui, China
| | - Bo Fang
- Laboratory of Atmospheric Physico-Chemistry, Anhui Institute of Optics and Fine Mechanics, HFIPS, Chinese Academy of Sciences, Hefei, 230031 Anhui, China
| | - Feihu Cheng
- Laboratory of Atmospheric Physico-Chemistry, Anhui Institute of Optics and Fine Mechanics, HFIPS, Chinese Academy of Sciences, Hefei, 230031 Anhui, China
| | - Xuezhe Xu
- Laboratory of Atmospheric Physico-Chemistry, Anhui Institute of Optics and Fine Mechanics, HFIPS, Chinese Academy of Sciences, Hefei, 230031 Anhui, China
| | - Shichuan Ni
- Laboratory of Atmospheric Physico-Chemistry, Anhui Institute of Optics and Fine Mechanics, HFIPS, Chinese Academy of Sciences, Hefei, 230031 Anhui, China.,University of Science and Technology of China, Hefei, 230026 Anhui, China
| | - Weijun Zhang
- Laboratory of Atmospheric Physico-Chemistry, Anhui Institute of Optics and Fine Mechanics, HFIPS, Chinese Academy of Sciences, Hefei, 230031 Anhui, China.,University of Science and Technology of China, Hefei, 230026 Anhui, China
| | - Chunxiang Ye
- College of Environmental Sciences and Engineering, Peking University, 100871 Beijing, China
| | - Weidong Chen
- Laboratoire de Physicochimie de l'Atmosphère, Université du Littoral Côte d'Opale, 59140 Dunkerque, France
| | - Dean S Venables
- School of Chemistry and Environmental Research Institute, University College Cork, T23 XE10 Cork, Ireland
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Gianella M, Press SA, Manfred KM, Norman HC, Islam M, Ritchie GAD. Sensitive detection of HO radicals produced in an atmospheric pressure plasma using Faraday rotation cavity ring-down spectroscopy. J Chem Phys 2019; 151:124202. [PMID: 31575168 DOI: 10.1063/1.5119191] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Cavity ring-down spectroscopy (CRDS) is a well-established, highly sensitive absorption technique whose sensitivity and selectivity for trace radical sensing can be further enhanced by measuring the polarization rotation of the intracavity light by the paramagnetic samples in the presence of a magnetic field. In this paper, we highlight the use of this Faraday rotation cavity ring-down spectroscopy (FR-CRDS) for the detection of HO2 radicals. In particular, we use a cold atmospheric pressure plasma jet as a highly efficient source of HO2 radicals and show that FR-CRDS in the near-infrared spectral region (1506 nm) has the potential to be a useful tool for studying radical chemistry. By simultaneously measuring ring-down times of orthogonal linearly polarized light, measurements of Faraday effect-induced rotation angles (θ) and absorption coefficients (α) are retrieved from the same data set. The Faraday rotation measurement exhibits better long-term stability and enhanced sensitivity due to its differential nature, whereby highly correlated noise between the two channels and slow drifts cancel out. The bandwidth-normalized sensitivities are αmin=2.2×10-11 cm-1 Hz-1/2 and θmin=0.62 nrad Hz-1/2. The latter corresponds to a minimum detectable (circular) birefringence of Δnmin=5×10-16 Hz-1/2. Using the overlapping qQ3(N = 4-9) transitions of HO2, we estimate limits of detection of 3.1 × 108 cm-3 based on traditional (absorption) CRDS methods and 6.7 × 107 cm-3 using FR-CRDS detection, where each point of the spectrum was acquired during 2 s. In addition, Verdet constants for pertinent carrier (He, Ar) and bulk (N2, O2) gases were recorded in this spectral region for the first time. These show good agreement with recent measurements of air and values extrapolated from reported Verdet constants at shorter wavelengths, demonstrating the potential of FR-CRDS for measurements of very weak Faraday effects and providing a quantitative validation to the computed rotation angles.
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Affiliation(s)
- Michele Gianella
- Department of Chemistry, Physical and Theoretical Chemistry Laboratory, University of Oxford, South Parks Rd., Oxford OX1 3QZ, United Kingdom
| | - Sioned A Press
- Department of Chemistry, Physical and Theoretical Chemistry Laboratory, University of Oxford, South Parks Rd., Oxford OX1 3QZ, United Kingdom
| | - Katherine M Manfred
- Department of Chemistry, Physical and Theoretical Chemistry Laboratory, University of Oxford, South Parks Rd., Oxford OX1 3QZ, United Kingdom
| | - Helen C Norman
- Department of Chemistry, Physical and Theoretical Chemistry Laboratory, University of Oxford, South Parks Rd., Oxford OX1 3QZ, United Kingdom
| | - Meez Islam
- School of Science, Engineering and Design, Teesside University, Borough Road, Middlesbrough TS1 3BA, United Kingdom
| | - Grant A D Ritchie
- Department of Chemistry, Physical and Theoretical Chemistry Laboratory, University of Oxford, South Parks Rd., Oxford OX1 3QZ, United Kingdom
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5
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Campos-Pineda M, Zhang J. Product yields of stabilized Criegee intermediates in the ozonolysis reactions of cis-2-butene, 2-methyl-2-butene, cyclopentene, and cyclohexene. Sci China Chem 2018. [DOI: 10.1007/s11426-017-9229-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/16/2022]
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6
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Yang C, Zhao W, Fang B, Xu X, Zhang Y, Gai Y, Zhang W, Venables DS, Chen W. Removing Water Vapor Interference in Peroxy Radical Chemical Amplification with a Large Diameter Nafion Dryer. Anal Chem 2018; 90:3307-3312. [DOI: 10.1021/acs.analchem.7b04830] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Chengqiang Yang
- Laboratory of Atmospheric Physico-Chemistry, Anhui Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Hefei 230031, Anhui, China
- School of Environmental Science and Optoelectronic Technology, University of Science and Technology of China, Hefei 230026, Anhui, China
| | - Weixiong Zhao
- Laboratory of Atmospheric Physico-Chemistry, Anhui Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Hefei 230031, Anhui, China
| | - Bo Fang
- Laboratory of Atmospheric Physico-Chemistry, Anhui Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Hefei 230031, Anhui, China
| | - Xuezhe Xu
- Laboratory of Atmospheric Physico-Chemistry, Anhui Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Hefei 230031, Anhui, China
| | - Yang Zhang
- Laboratory of Atmospheric Physico-Chemistry, Anhui Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Hefei 230031, Anhui, China
| | - Yanbo Gai
- Laboratory of Atmospheric Physico-Chemistry, Anhui Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Hefei 230031, Anhui, China
| | - Weijun Zhang
- Laboratory of Atmospheric Physico-Chemistry, Anhui Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Hefei 230031, Anhui, China
- School of Environmental Science and Optoelectronic Technology, University of Science and Technology of China, Hefei 230026, Anhui, China
| | - Dean S. Venables
- School of Chemistry and Environmental Research Institute, University College Cork, Cork T23 XE10, Ireland
| | - Weidong Chen
- Laboratoire de Physicochimie de l’Atmosphère, Université du Littoral Côte d’Opale, 59140 Dunkerque, France
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7
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Chen Y, Yang C, Zhao W, Fang B, Xu X, Gai Y, Lin X, Chen W, Zhang W. Ultra-sensitive measurement of peroxy radicals by chemical amplification broadband cavity-enhanced spectroscopy. Analyst 2016; 141:5870-5878. [DOI: 10.1039/c6an01038e] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The chemical amplification method is combined with the incoherent broadband cavity-enhanced absorption spectroscopy for peroxy radical measurements.
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Affiliation(s)
- Yang Chen
- Laboratory of Atmospheric Physico-Chemistry
- Anhui Institute of Optics and Fine Mechanics
- Chinese Academy of Sciences
- Hefei
- China
| | - Chengqiang Yang
- Laboratory of Atmospheric Physico-Chemistry
- Anhui Institute of Optics and Fine Mechanics
- Chinese Academy of Sciences
- Hefei
- China
| | - Weixiong Zhao
- Laboratory of Atmospheric Physico-Chemistry
- Anhui Institute of Optics and Fine Mechanics
- Chinese Academy of Sciences
- Hefei
- China
| | - Bo Fang
- Laboratory of Atmospheric Physico-Chemistry
- Anhui Institute of Optics and Fine Mechanics
- Chinese Academy of Sciences
- Hefei
- China
| | - Xuezhe Xu
- Laboratory of Atmospheric Physico-Chemistry
- Anhui Institute of Optics and Fine Mechanics
- Chinese Academy of Sciences
- Hefei
- China
| | - Yanbo Gai
- Laboratory of Atmospheric Physico-Chemistry
- Anhui Institute of Optics and Fine Mechanics
- Chinese Academy of Sciences
- Hefei
- China
| | - Xiaoxiao Lin
- Laboratory of Atmospheric Physico-Chemistry
- Anhui Institute of Optics and Fine Mechanics
- Chinese Academy of Sciences
- Hefei
- China
| | - Weidong Chen
- Laboratoire de Physicochimie de l'Atmosphère
- Université du Littoral Côte d'Opale
- 59140 Dunkerque
- France
| | - Weijun Zhang
- Laboratory of Atmospheric Physico-Chemistry
- Anhui Institute of Optics and Fine Mechanics
- Chinese Academy of Sciences
- Hefei
- China
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8
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Liu Y, Zhang J. Atmospheric Peroxy Radical Measurements Using Dual-Channel Chemical Amplification Cavity Ringdown Spectroscopy. Anal Chem 2014; 86:5391-8. [DOI: 10.1021/ac5004689] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Affiliation(s)
- Yingdi Liu
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California 91109, United States
| | - Jingsong Zhang
- Department of Chemistry and
Air Pollution Research Center, University of California, Riverside, California 92521, United States
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9
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Kim S, Guenther A, Apel E. Quantitative and qualitative sensing techniques for biogenic volatile organic compounds and their oxidation products. ENVIRONMENTAL SCIENCE. PROCESSES & IMPACTS 2013; 15:1301-1314. [PMID: 23748571 DOI: 10.1039/c3em00040k] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
The physiological production mechanisms of some of the organics in plants, commonly known as biogenic volatile organic compounds (BVOCs), have been known for more than a century. Some BVOCs are emitted to the atmosphere and play a significant role in tropospheric photochemistry especially in ozone and secondary organic aerosol (SOA) productions as a result of interplays between BVOCs and atmospheric radicals such as hydroxyl radical (OH), ozone (O3) and NOX (NO + NO2). These findings have been drawn from comprehensive analysis of numerous field and laboratory studies that have characterized the ambient distribution of BVOCs and their oxidation products, and reaction kinetics between BVOCs and atmospheric oxidants. These investigations are limited by the capacity for identifying and quantifying these compounds. This review highlights the major analytical techniques that have been used to observe BVOCs and their oxidation products such as gas chromatography, mass spectrometry with hard and soft ionization methods, and optical techniques from laser induced fluorescence (LIF) to remote sensing. In addition, we discuss how new analytical techniques can advance our understanding of BVOC photochemical processes. The principles, advantages, and drawbacks of the analytical techniques are discussed along with specific examples of how the techniques were applied in field and laboratory measurements. Since a number of thorough review papers for each specific analytical technique are available, readers are referred to these publications rather than providing thorough descriptions of each technique. Therefore, the aim of this review is for readers to grasp the advantages and disadvantages of various sensing techniques for BVOCs and their oxidation products and to provide guidance for choosing the optimal technique for a specific research task.
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Affiliation(s)
- Saewung Kim
- Department of Earth System Science, School of Physical Sciences, University of California, Irvine, Irvine, CA 92697, USA.
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10
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Measurement of aerosol optical extinction using diode laser cavity ringdown spectroscopy. CHINESE SCIENCE BULLETIN-CHINESE 2013. [DOI: 10.1007/s11434-013-5825-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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11
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Bell CL, van Helden JPH, Blaikie TPJ, Hancock G, van Leeuwen NJ, Peverall R, Ritchie GAD. Noise-Immune Cavity-Enhanced Optical Heterodyne Detection of HO2 in the Near-Infrared Range. J Phys Chem A 2012; 116:5090-9. [DOI: 10.1021/jp301038r] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Affiliation(s)
- Claire L Bell
- Physical & Theoretical Chemistry Laboratory, Department of Chemistry, University of Oxford, South Parks Road, Oxford OX1 3QZ, UK
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12
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Alecu IM, Truhlar DG. Computational Study of the Reactions of Methanol with the Hydroperoxyl and Methyl Radicals. 2. Accurate Thermal Rate Constants. J Phys Chem A 2011; 115:14599-611. [DOI: 10.1021/jp209029p] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Affiliation(s)
- I. M. Alecu
- Department of Chemistry and Supercomputing Institute, University of Minnesota, Minneapolis, Minnesota 55455-0431, United States
| | - Donald G. Truhlar
- Department of Chemistry and Supercomputing Institute, University of Minnesota, Minneapolis, Minnesota 55455-0431, United States
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13
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Affiliation(s)
- Thorsten Hoffmann
- Institute of Inorganic and Analytical Chemistry, Johannes Gutenberg-University, Mainz, Germany
| | - Ru-Jin Huang
- Institute of Inorganic and Analytical Chemistry, Johannes Gutenberg-University, Mainz, Germany
| | - Markus Kalberer
- Department of Chemistry, University of Cambridge, Cambridge, United Kingdom
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14
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Washenfelder RA, Wagner NL, Dube WP, Brown SS. Measurement of atmospheric ozone by cavity ring-down spectroscopy. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2011; 45:2938-2944. [PMID: 21366216 DOI: 10.1021/es103340u] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Ozone plays a key role in both the Earth's radiative budget and photochemistry. Accurate, robust analytical techniques for measuring its atmospheric abundance are of critical importance. Cavity ring-down spectroscopy has been successfully used for sensitive and accurate measurements of many atmospheric species. However, this technique has not been used for atmospheric measurements of ozone, because the strongest ozone absorption bands occur in the ultraviolet spectral region, where Rayleigh and Mie scattering cause significant cavity losses and dielectric mirror reflectivities are limited. Here, we describe a compact instrument that measures O3 by chemical conversion to NO2 in excess NO, with subsequent detection by cavity ring-down spectroscopy. This method provides a simple, accurate, and high-precision measurement of atmospheric ozone. The instrument consists of two channels. The sum of NO2 and converted O3 (defined as Ox) is measured in the first channel, while NO2 alone is measured in the second channel. NO2 is directly detected in each channel by cavity ring-down spectroscopy with a laser diode light source at 404 nm. The limit of detection for O3 is 26 pptv (2 sigma precision) at 1 s time resolution. The accuracy of the measurement is ±2.2%, with the largest uncertainty being the effective NO2 absorption cross-section. The linear dynamic range of the instrument has been verified from the detection limit to above 200 ppbv (r2>99.99%). The observed precision on signal (2 sigma) with 41 ppbv O3 is 130 pptv in 1 s. Comparison of this instrument to UV absorbance instruments for ambient O3 concentrations shows linear agreement (r2=99.1%) with slope of 1.012±0.002.
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Affiliation(s)
- R A Washenfelder
- Cooperative Institute for Research in Environmental Sciences, 216 UCB, University of Colorado, Boulder, Colorado 80309, United States.
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