1
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Cotterell MI, Knight JW, Reid JP, Orr-Ewing AJ. Accurate Measurement of the Optical Properties of Single Aerosol Particles Using Cavity Ring-Down Spectroscopy. J Phys Chem A 2022; 126:2619-2631. [PMID: 35467353 PMCID: PMC9082593 DOI: 10.1021/acs.jpca.2c01246] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2022] [Revised: 04/06/2022] [Indexed: 11/29/2022]
Abstract
New approaches for the sensitive and accurate quantification of aerosol optical properties are needed to improve the current understanding of the unique physical chemistry of airborne particles and to explore their roles in fields as diverse as chemical manufacturing, healthcare, and atmospheric science. We have pioneered the use of cavity ring-down spectroscopy (CRDS), with concurrent angularly resolved elastic light scattering measurements, to interrogate the optical properties of single aerosol particles levitated in optical and electrodynamic traps. This approach enables the robust quantification of optical properties such as extinction cross sections for individual particles of known size. Our measurements can now distinguish the scattering and absorption contributions to the overall light extinction, from which the real and imaginary components of the complex refractive indices can be retrieved and linked to chemical composition. In this Feature Article, we show that this innovative measurement platform enables accurate and precise optical measurements for spherical and nonspherical particles, whether nonabsorbing or absorbing at the CRDS probe wavelength. We discuss the current limitations of our approach and the key challenges in physical and atmospheric chemistry that can now be addressed by CRDS measurements for single aerosol particles levitated in controlled environments.
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Affiliation(s)
- M. I. Cotterell
- School
of Chemistry, University of Bristol, Cantock’s Close, Bristol BS8 1TS, U.K.
| | - J. W. Knight
- School
of Chemistry, University of Bristol, Cantock’s Close, Bristol BS8 1TS, U.K.
| | - J. P. Reid
- School
of Chemistry, University of Bristol, Cantock’s Close, Bristol BS8 1TS, U.K.
| | - A. J. Orr-Ewing
- School
of Chemistry, University of Bristol, Cantock’s Close, Bristol BS8 1TS, U.K.
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2
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Cheng C, Liu S, Qi H, Hu P, Ye P, Pan S. Optical-feedback cavity ring-down spectroscopy for NO 2 extinction coefficient measurement using a continuous wave laser diode. APPLIED OPTICS 2022; 61:2230-2236. [PMID: 35333238 DOI: 10.1364/ao.450874] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/08/2021] [Accepted: 02/11/2022] [Indexed: 06/14/2023]
Abstract
Optical-feedback (OF) cavity ring-down spectroscopy consisting of a linear cavity is developed by employing a continuous wave laser diode (LD) with multi-longitudinal modes. Due to the OF effect caused by the cavity output laser back into the LD, the laser frequency is locked, and the intracavity laser intensity is enhanced. We use different concentrations of NO2 gases to test the apparatus, and the results show good agreement with theoretical values. Owing to the compactness of the laser source and high detection accuracy, the device can be used for detection of low-concentration absorbent gases in the environmental monitoring field.
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3
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Ma G, He Y, Chen B, Deng H, Liu Y, Wang X, Zhao Z, Kan R. Quasi-Simultaneous Sensitive Detection of Two Gas Species by Cavity-Ringdown Spectroscopy with Two Lasers. SENSORS (BASEL, SWITZERLAND) 2021; 21:7622. [PMID: 34833699 PMCID: PMC8624139 DOI: 10.3390/s21227622] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/08/2021] [Revised: 10/28/2021] [Accepted: 11/03/2021] [Indexed: 11/26/2022]
Abstract
We developed a cavity ringdown spectrometer by utilizing a step-scanning and dithering method for matching laser wavelengths to optical resonances of an optical cavity. Our approach is capable of working with two and more lasers for quasi-simultaneous measurements of multiple gas species. The developed system was tested with two lasers operating around 1654 nm and 1658 nm for spectral detections of 12CH4 and its isotope 13CH4 in air, respectively. The ringdown time of the empty cavity was about 340 µs. The achieved high detection sensitivity of a noise-equivalent absorption coefficient was 2.8 × 10-11 cm-1 Hz-1/2 or 1 × 10-11 cm-1 by averaging for 30 s. The uncertainty of the high precision determination of δ13CH4 in air is about 1.3‰. Such a system will be useful for future applications such as environmental monitoring.
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Affiliation(s)
- Guosheng Ma
- Anhui Institute of Optics and Fine Mechanics, Hefei Institutes of Physical Sciences, Chinese Academy of Sciences, Hefei 230031, China; (G.M.); (Y.H.); (B.C.); (H.D.); (Y.L.)
- Graduate School of Science Island Branch, University of Science and Technology of China, Hefei 230026, China
| | - Yabai He
- Anhui Institute of Optics and Fine Mechanics, Hefei Institutes of Physical Sciences, Chinese Academy of Sciences, Hefei 230031, China; (G.M.); (Y.H.); (B.C.); (H.D.); (Y.L.)
| | - Bing Chen
- Anhui Institute of Optics and Fine Mechanics, Hefei Institutes of Physical Sciences, Chinese Academy of Sciences, Hefei 230031, China; (G.M.); (Y.H.); (B.C.); (H.D.); (Y.L.)
| | - Hao Deng
- Anhui Institute of Optics and Fine Mechanics, Hefei Institutes of Physical Sciences, Chinese Academy of Sciences, Hefei 230031, China; (G.M.); (Y.H.); (B.C.); (H.D.); (Y.L.)
| | - Ying Liu
- Anhui Institute of Optics and Fine Mechanics, Hefei Institutes of Physical Sciences, Chinese Academy of Sciences, Hefei 230031, China; (G.M.); (Y.H.); (B.C.); (H.D.); (Y.L.)
- Graduate School of Science Island Branch, University of Science and Technology of China, Hefei 230026, China
| | - Xingping Wang
- School of Engineering Science, University of Science and Technology of China, Hefei 230026, China;
| | - Zhihao Zhao
- College of Information Science and Engineering, Northeastern University, Shenyang 110819, China;
| | - Ruifeng Kan
- Anhui Institute of Optics and Fine Mechanics, Hefei Institutes of Physical Sciences, Chinese Academy of Sciences, Hefei 230031, China; (G.M.); (Y.H.); (B.C.); (H.D.); (Y.L.)
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4
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Gupta K, Shenoy MR. Compact setup to determine size and concentration of spherical particles in a turbid medium. APPLIED OPTICS 2021; 60:8174-8180. [PMID: 34613081 DOI: 10.1364/ao.435596] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Accepted: 08/12/2021] [Indexed: 06/13/2023]
Abstract
We propose a compact setup to determine the size and concentration of spherical particles in a turbid medium. A pair of plane mirrors is used to multifold the undeviated laser beam, and measure it at a detector placed close to the sample, to determine the interaction coefficient. The size of particles is uniquely determined by comparison of the scattered light from the medium, measured at two separate detectors placed at two different angular positions, with that from Monte Carlo simulations. The methodology is verified using measurements with turbid samples comprising polystyrene spheres.
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5
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Valenzuela A, Chu F, Haddrell AE, Cotterell MI, Walker JS, Orr-Ewing AJ, Reid JP. Optical Interrogation of Single Levitated Droplets in a Linear Quadrupole Trap by Cavity Ring-Down Spectroscopy. J Phys Chem A 2021; 125:394-405. [PMID: 33355458 DOI: 10.1021/acs.jpca.0c09213] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Optical trapping is a well-established technique to manipulate and levitate micro- and nanoscale particles and droplets. However, optical traps for single aerosol studies are most often limited to trapping spherical nonabsorbing droplets, and a universal optical trap for the stable confinement of particles regardless of their absorption strength and morphology is not established. Instead, new opportunities arise from levitating droplets using electrodynamic traps. Here, using a combined electrodynamic linear quadrupole trap and a cavity ring-down spectrometer, we demonstrate that it is possible to trap single droplets and simultaneously measure their extinction cross sections and elastic scattering phase functions over extended periods of time. To test the novel setup, we evaluated the evaporation of 1,2,6-hexanetriol under low-humidity conditions, and the evolution of aqueous (NH4)2SO4 and NaCl droplets experiencing changing environmental conditions. Our studies extended beyond spherical droplets and we measured particle extinction cross sections after the efflorescence (crystallization) of the inorganic salt particles. Comparison of measured cross sections for crystallized particles with light scattering model predictions (using Mie theory or the T-matrix/extended boundary-condition method (EBCM) implementations for random orientation, with either the spheroid or superellipsoid parameterizations) enables information on particle shape to be inferred. Specifically, we find that cross sections for dry (NH4)2SO4 particles are accounted for by Mie theory and, thus, particle shape is represented well by a sphere. Conversely, the cross sections for dry NaCl particles are only reconciled with light scattering models pertaining to nonspherical shapes. These results will have implications for accurate remote sensing retrievals of dry salt optical properties and for parameterizations implemented in radiative forcing calculations with changing humidity. Moreover, our new platform for precise and accurate measurement of optical properties of micron-scale and sub-micron particles has potential applications in a range of areas of atmospheric science, such as precise light scattering measurements for ice crystals and mineral dust. It represents a promising step toward accurate characterizations of optical properties for nonspherical and light-absorbing aerosols.
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Affiliation(s)
- Antonio Valenzuela
- Department of Applied Physics, University of Granada, Granada 18071, Spain.,Andalusian Institute for Earth System Research (IISTA-CEAMA), Granada 18006, Spain
| | - Fenghong Chu
- Shanghai University of Electric Power, Shanghai 200090, China
| | - Allen E Haddrell
- School of Chemistry, University of Bristol, Bristol BS8 1TS, U.K
| | | | - Jim S Walker
- School of Chemistry, University of Bristol, Bristol BS8 1TS, U.K
| | | | - Jonathan P Reid
- School of Chemistry, University of Bristol, Bristol BS8 1TS, U.K
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6
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Willoughby RE, Cotterell MI, Lin H, Orr-Ewing AJ, Reid JP. Measurements of the Imaginary Component of the Refractive Index of Weakly Absorbing Single Aerosol Particles. J Phys Chem A 2017; 121:5700-5710. [DOI: 10.1021/acs.jpca.7b05418] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Rose E. Willoughby
- School
of Chemistry, University of Bristol, Cantock’s Close, Bristol BS8 1TS, United Kingdom
| | - Michael I. Cotterell
- School
of Chemistry, University of Bristol, Cantock’s Close, Bristol BS8 1TS, United Kingdom
- College
for Engineering, Mathematics and Physical Sciences, University of Exeter, Exeter EX4 4QF, United Kingdom
- Aerosol
Observation Based Research, Met Office, Exeter EX1 3PB, United Kingdom
| | - Hongze Lin
- College
of Optical Science and Engineering, Zhejiang University, Hangzhou 310058, China
| | - Andrew J. Orr-Ewing
- School
of Chemistry, University of Bristol, Cantock’s Close, Bristol BS8 1TS, United Kingdom
| | - Jonathan P. Reid
- School
of Chemistry, University of Bristol, Cantock’s Close, Bristol BS8 1TS, United Kingdom
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7
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Gong Z, Pan YL, Wang C. Characterization of single airborne particle extinction using the tunable optical trap-cavity ringdown spectroscopy (OT-CRDS) in the UV. OPTICS EXPRESS 2017; 25:6732-6745. [PMID: 28381017 DOI: 10.1364/oe.25.006732] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
We integrated a rigid optical trap into a tunable pulsed cavity ringdown spectroscopy (OT-CRDS) system to characterize the extinction of single airborne particles in the UV spectral region (306-315 nm). Single solid particles from a multi-walled carbon nanotube (MWCNT), Bermuda grass smut spore, carbon microsphere, and blackened polyethylene microsphere were trapped in air based on the photophoretic force. The improved OT-CRDS system was highly sensitive and able to resolve extinctions of single particles from different materials and sizes at a given wavelength. Further, we successfully manipulated the number of particles, e.g., 1, 2 or more particles, in the trap and measured their distinguishable extinctions using the OT-CRDS. We also show that the particle size and extinction have a good linear correlation from the measurements of 24 single MWCNT particles. Material- and wavelength-dependent extinctions of the four types of airborne particles were also characterized. Results reveal that single airborne particles regardless of their differences in material and size, due to their heterogeneous morphology, have individual-particle dependent extinctions and that dependence can be resolved and characterized using the OT-CRDS technique.
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8
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McHale LE, Hecobian A, Yalin AP. Open-path cavity ring-down spectroscopy for trace gas measurements in ambient air. OPTICS EXPRESS 2016; 24:5523-5535. [PMID: 29092375 DOI: 10.1364/oe.24.005523] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
The present work used a near-infrared methane cavity ring-down spectroscopy (CRDS) sensor to examine performance and limitations of open-path CRDS for atmospheric measurements. A simple purge-enclosure was developed to maintain high mirror reflectivity and allowed >100 hours of operation with mirror reflectivity above 0.99996. We characterized effects of aerosols on ring-down decay signals and found the dominant effect to be fluctuations by large super-micron particles. Simple software filtering approaches were developed to combat these fluctuations allowing noise-equivalent sensitivity of ~6x10-10 cm-1HJ Hz-1/2 within a factor of ~3 of closed-path systems (based on stability of the absorption baseline). Sensor measurements were validated against known methane concentrations in a closed-path configuration, while open-path validation was performed by side-by-side comparison with a commercial closed-path system.
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9
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Mason BJ, Cotterell MI, Preston TC, Orr-Ewing AJ, Reid JP. Direct Measurements of the Optical Cross Sections and Refractive Indices of Individual Volatile and Hygroscopic Aerosol Particles. J Phys Chem A 2015; 119:5701-13. [DOI: 10.1021/acs.jpca.5b00435] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- B. J. Mason
- School
of Chemistry, University of Bristol, Bristol, BS8 1TS, U.K
| | - M. I. Cotterell
- School
of Chemistry, University of Bristol, Bristol, BS8 1TS, U.K
| | - T. C. Preston
- Department
of Atmospheric and Oceanic Sciences and Department of Chemistry, McGill University, 801 Sherbrooke West, Montreal, QC, Canada H3A 0B9
| | - A. J. Orr-Ewing
- School
of Chemistry, University of Bristol, Bristol, BS8 1TS, U.K
| | - J. P. Reid
- School
of Chemistry, University of Bristol, Bristol, BS8 1TS, U.K
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10
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Cotterell MI, Mason BJ, Preston TC, Orr-Ewing AJ, Reid JP. Optical extinction efficiency measurements on fine and accumulation mode aerosol using single particle cavity ring-down spectroscopy. Phys Chem Chem Phys 2015; 17:15843-56. [DOI: 10.1039/c5cp00252d] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
We report a new single aerosol particle approach using cavity ringdown spectroscopy to accurately determine optical extinction cross sections at multiple wavelengths.
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Affiliation(s)
| | | | - Thomas C. Preston
- Department of Atmospheric and Oceanic Sciences and Department of Chemistry
- McGill University
- Montreal
- Canada
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11
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Tang Y, Huang Y, Li L, Chen H, Chen J, Yang X, Gao S, Gross DS. Characterization of aerosol optical properties, chemical composition and mixing states in the winter season in Shanghai, China. J Environ Sci (China) 2014; 26:2412-2422. [PMID: 25499489 DOI: 10.1016/j.jes.2014.03.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2014] [Revised: 03/25/2014] [Accepted: 04/11/2014] [Indexed: 06/04/2023]
Abstract
Physical and chemical properties of ambient aerosols at the single particle level were studied in Shanghai from December 22 to 28, 2009. A Cavity-Ring-Down Aerosol Extinction Spectrometer (CRD-AES) and a nephelometer were deployed to measure aerosol light extinction and scattering properties, respectively. An Aerosol Time-of-Flight Mass Spectrometer (ATOFMS) was used to detect single particle sizes and chemical composition. Seven particle types were detected. Air parcels arrived at the sampling site from the vicinity of Shanghai until mid-day of December 25, when they started to originate from North China. The aerosol extinction, scattering, and absorption coefficients all dropped sharply when this cold, clean air arrived. Aerosol particles changed from a highly aged type before this meteorological shift to a relatively fresh type afterwards. The aerosol optical properties were dependent on the wind direction. Aerosols with high extinction coefficient and scattering Ångström exponent (SAE) were observed when the wind blew from the west and northwest, indicating that they were predominantly fine particles. Nitrate and ammonium correlated most strongly with the change in aerosol optical properties. In the elemental carbon/organic carbon (ECOC) particle type, the diurnal trends of single scattering albedo (SSA) and elemental carbon (EC) signal intensity had a negative correlation. We also found a negative correlation (r=-0.87) between high mass-OC particle number fraction and the SSA in a relatively clean period, suggesting that particulate aromatic components might play an important role in light absorption in urban areas.
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Affiliation(s)
- Yong Tang
- Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention, Department of Environmental Science and Engineering, Fudan University, Shanghai 200433, China
| | - Yuanlong Huang
- Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention, Department of Environmental Science and Engineering, Fudan University, Shanghai 200433, China
| | - Ling Li
- Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention, Department of Environmental Science and Engineering, Fudan University, Shanghai 200433, China
| | - Hong Chen
- Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention, Department of Environmental Science and Engineering, Fudan University, Shanghai 200433, China
| | - Jianmin Chen
- Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention, Department of Environmental Science and Engineering, Fudan University, Shanghai 200433, China; Fudan-Tyndall Center, Fudan University, Shanghai 200433, China
| | - Xin Yang
- Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention, Department of Environmental Science and Engineering, Fudan University, Shanghai 200433, China; Fudan-Tyndall Center, Fudan University, Shanghai 200433, China.
| | - Song Gao
- Division of Math, Science and Technology, Nova Southeastern University, Fort Lauderdale, FL 33314, USA
| | - Deborah S Gross
- Department of Chemistry, Carleton College, Northfield, MN 55057, USA
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12
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Mason BJ, Walker JS, Reid JP, Orr-Ewing AJ. Deviations from Plane-Wave Mie Scattering and Precise Retrieval of Refractive Index for a Single Spherical Particle in an Optical Cavity. J Phys Chem A 2014; 118:2083-8. [DOI: 10.1021/jp5014863] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Affiliation(s)
- Bernard J. Mason
- School of Chemistry, University of Bristol, Bristol BS8 1TS, U.K
| | - Jim S. Walker
- School of Chemistry, University of Bristol, Bristol BS8 1TS, U.K
| | - Jonathan P. Reid
- School of Chemistry, University of Bristol, Bristol BS8 1TS, U.K
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13
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Cavity Enhanced Absorption Spectroscopy with Optical Feedback. SPRINGER SERIES IN OPTICAL SCIENCES 2014. [DOI: 10.1007/978-3-642-40003-2_5] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
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14
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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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15
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Walker JS, Carruthers AE, Orr-Ewing AJ, Reid JP. Measurements of Light Extinction by Single Aerosol Particles. J Phys Chem Lett 2013; 4:1748-1752. [PMID: 26282989 DOI: 10.1021/jz4008068] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
A Bessel beam optical trap is combined with continuous wave cavity ringdown spectroscopy to measure the extinction cross section of individual aerosol particles. Particles, ∼1 μm in size, can be captured indefinitely and processes that transform size or refractive index studied. The measured light extinction induced by the particle is shown to depend on the position of the particle in the cavity, allowing accurate measurements of the mode structure of a high finesse optical cavity without significant perturbation. The variation in extinction efficiency of a sodium chloride droplet with relative humidity is shown to agree well with predictions from Mie scattering theory.
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Affiliation(s)
- Jim S Walker
- School of Chemistry, University of Bristol, Bristol, United Kingdom BS8 1TS
| | | | - Andrew J Orr-Ewing
- School of Chemistry, University of Bristol, Bristol, United Kingdom BS8 1TS
| | - Jonathan P Reid
- School of Chemistry, University of Bristol, Bristol, United Kingdom BS8 1TS
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16
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Tan Z, Long X. A developed optical-feedback cavity ring-down spectrometer and its application. APPLIED SPECTROSCOPY 2012; 66:492-495. [PMID: 22524954 DOI: 10.1366/11-06291] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
A developed spectrometer based on optical-feedback cavity ring-down spectroscopy (OF-CRDS) has been demonstrated with a distributed feedback laser diode and a V-shaped glass ceramic cavity. The laser is coupled to the V-shaped cavity, which creates an absorption path length greater than 2.8 km, and resonance between the laser frequency and the cavity modes is realized by modulating the cavity length instead of tuning the laser wavelength to obtain a higher resolution. A noise-equivalent absorption coefficient of ~2.6 × 10(-8) cm(-1)Hz(-1/2) (1σ) is determined with spectral resolution of ~0.003 cm(-1) and spectral range of 1.2 cm(-1). As an application example, the absorption spectrum measurement of water vapor in the spectral range of 6590.3~6591.5 cm(-1) is demonstrated with this spectrometer.
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Affiliation(s)
- Zhongqi Tan
- College of Opto-electric Science and Engineering, National University of Defense Technology, Changsha, Hunan 410073, China.
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17
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Smith GS. Estimate for the effect of forward scattering on the measurement of extinction for particles by cavity ringdown spectroscopy. APPLIED OPTICS 2011; 50:5422-5429. [PMID: 22016208 DOI: 10.1364/ao.50.005422] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
An analytical model is formulated for the extinction of light by particles in a cavity ringdown spectroscopy measurement. The electromagnetic field inside the cavity is assumed to be the lowest-order Gaussian beam, and the scattering by the particles is incorporated using van de Hulst's approximation for the scattering by a sphere. This model includes both coherent scattering in the forward direction and strong scattering in the forward direction for electrically large particles. The model is used to estimate the amount of energy scattered by the particles that is coupled back into the incident beam. The consequences of this coupling for the measurement of the extinction cross section of spherical particles are examined.
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Affiliation(s)
- Glenn S Smith
- School of Electrical and Computer Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332-0250, USA.
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18
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19
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Mellon D, King SJ, Kim J, Reid JP, Orr-Ewing AJ. Measurements of Extinction by Aerosol Particles in the Near-Infrared Using Continuous Wave Cavity Ring-Down Spectroscopy. J Phys Chem A 2011; 115:774-83. [DOI: 10.1021/jp109894x] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Daniel Mellon
- School of Chemistry, University of Bristol, Cantock’s Close, Bristol BS8 1TS, United Kingdom
| | - Simon J. King
- School of Chemistry, University of Bristol, Cantock’s Close, Bristol BS8 1TS, United Kingdom
| | - Jin Kim
- School of Chemistry, University of Bristol, Cantock’s Close, Bristol BS8 1TS, United Kingdom
| | - Jonathan P. Reid
- School of Chemistry, University of Bristol, Cantock’s Close, Bristol BS8 1TS, United Kingdom
| | - Andrew J. Orr-Ewing
- School of Chemistry, University of Bristol, Cantock’s Close, Bristol BS8 1TS, United Kingdom
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20
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Hippler M, Mohr C, Keen KA, McNaghten ED. Cavity-enhanced resonant photoacoustic spectroscopy with optical feedback cw diode lasers: A novel technique for ultratrace gas analysis and high-resolution spectroscopy. J Chem Phys 2010; 133:044308. [PMID: 20687651 DOI: 10.1063/1.3461061] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Cavity-enhanced resonant photoacoustic spectroscopy with optical feedback cw diode lasers (OF-CERPAS) is introduced as a novel technique for ultratrace gas analysis and high-resolution spectroscopy. In the scheme, a single-mode cw diode laser (3 mW, 635 nm) is coupled into a high-finesse linear cavity and stabilized to the cavity by optical feedback. Inside the cavity, a build-up of laser power to at least 2.5 W occurs. Absorbing gas phase species inside the cavity are detected with high sensitivity by the photoacoustic effect using a microphone embedded in the cavity. To increase sensitivity further, coupling into the cavity is modulated at a frequency corresponding to a longitudinal resonance of an organ pipe acoustic resonator (f=1.35 kHz and Q approximately 10). The technique has been characterized by measuring very weak water overtone transitions near 635 nm. Normalized noise-equivalent absorption coefficients are determined as alpha approximately 4.4x10(-9) cm(-1) s(1/2) (1 s integration time) and 2.6x10(-11) cm(-1) s(1/2) W (1 s integration time and 1 W laser power). These sensitivities compare favorably with existing state-of-the-art techniques. As an advantage, OF-CERPAS is a "zero-background" method which increases selectivity and sensitivity, and its sensitivity scales with laser power.
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Affiliation(s)
- Michael Hippler
- Department of Chemistry, University of Sheffield, Sheffield S3 7HF, United Kingdom.
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21
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Miles REH, Rudić S, Orr-Ewing AJ, Reid JP. Influence of Uncertainties in the Diameter and Refractive Index of Calibration Polystyrene Beads on the Retrieval of Aerosol Optical Properties Using Cavity Ring Down Spectroscopy. J Phys Chem A 2010; 114:7077-84. [DOI: 10.1021/jp103246t] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
| | - Svemir Rudić
- School of Chemistry, University of Bristol, Bristol BS8 1TS, United Kingdom
| | | | - Jonathan P. Reid
- School of Chemistry, University of Bristol, Bristol BS8 1TS, United Kingdom
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22
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Dial KD, Hiemstra S, Thompson JE. Simultaneous Measurement of Optical Scattering and Extinction on Dispersed Aerosol Samples. Anal Chem 2010; 82:7885-96. [DOI: 10.1021/ac100617j] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Kathy D. Dial
- Department of Chemistry & Biochemistry, MS1061, Texas Tech University, Lubbock, Texas 79409
| | - Scott Hiemstra
- Department of Chemistry & Biochemistry, MS1061, Texas Tech University, Lubbock, Texas 79409
| | - Jonathan E. Thompson
- Department of Chemistry & Biochemistry, MS1061, Texas Tech University, Lubbock, Texas 79409
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Lang-Yona N, Abo-Riziq A, Erlick C, Segre E, Trainic M, Rudich Y. Interaction of internally mixed aerosols with light. Phys Chem Chem Phys 2010; 12:21-31. [DOI: 10.1039/b913176k] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Fiddler MN, Begashaw I, Mickens MA, Collingwood MS, Assefa Z, Bililign S. Laser spectroscopy for atmospheric and environmental sensing. SENSORS 2009; 9:10447-512. [PMID: 22303184 PMCID: PMC3267232 DOI: 10.3390/s91210447] [Citation(s) in RCA: 80] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/18/2009] [Accepted: 12/02/2009] [Indexed: 12/12/2022]
Abstract
Lasers and laser spectroscopic techniques have been extensively used in several applications since their advent, and the subject has been reviewed extensively in the last several decades. This review is focused on three areas of laser spectroscopic applications in atmospheric and environmental sensing; namely laser-induced fluorescence (LIF), cavity ring-down spectroscopy (CRDS), and photoluminescence (PL) techniques used in the detection of solids, liquids, aerosols, trace gases, and volatile organic compounds (VOCs).
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Affiliation(s)
- Marc N. Fiddler
- NOAA-ISET Center, North Carolina A&T State University, 1601 E Market Street Greensboro, NC 27411, USA; E-Mail:
| | - Israel Begashaw
- Department of Physics, North Carolina A&T State University, Greensboro, 1601 E Market Street, Marteena Hall, Greensboro, NC 27411, USA; E-Mail:
| | - Matthew A. Mickens
- Department of Chemistry, North Carolina A&T State University, 1601 E Market Street, New Science Building, Greensboro, NC 27411, USA; E-Mail:
- Energy & Environmental Systems Program, North Carolina A&T State University, 1601 E Market Street, Greensboro, NC 27411, USA; E-Mail:
| | - Michael S. Collingwood
- Energy & Environmental Systems Program, North Carolina A&T State University, 1601 E Market Street, Greensboro, NC 27411, USA; E-Mail:
| | - Zerihun Assefa
- NOAA-ISET Center, North Carolina A&T State University, 1601 E Market Street Greensboro, NC 27411, USA; E-Mail:
- Department of Chemistry, North Carolina A&T State University, 1601 E Market Street, New Science Building, Greensboro, NC 27411, USA; E-Mail:
- Authors to whom correspondence should be addressed; E-Mails: (Z.A.); (S.B.); Tel.: +1-336-285-2328/2255; Fax: +1-336-256-2542/ 334-7124
| | - Solomon Bililign
- NOAA-ISET Center, North Carolina A&T State University, 1601 E Market Street Greensboro, NC 27411, USA; E-Mail:
- Department of Physics, North Carolina A&T State University, Greensboro, 1601 E Market Street, Marteena Hall, Greensboro, NC 27411, USA; E-Mail:
- Authors to whom correspondence should be addressed; E-Mails: (Z.A.); (S.B.); Tel.: +1-336-285-2328/2255; Fax: +1-336-256-2542/ 334-7124
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Butler TJA, Mellon D, Kim J, Litman J, Orr-Ewing AJ. Optical-feedback cavity ring-down spectroscopy measurements of extinction by aerosol particles. J Phys Chem A 2009; 113:3963-72. [PMID: 19249854 DOI: 10.1021/jp810310b] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Optical feedback cavity ring-down spectroscopy (OF-CRDS) using a continuous wave distributed feedback diode laser at 1650 nm has been used to measure extinction of light by samples of monodisperse spherical aerosol particles <1 mum in diameter. The OF-CRDS method allows measurements of low levels of extinction of incident light to be made at repetition rates of 1 kHz or greater. A statistical model is proposed to describe the linear relationship between the extinction coefficient (alpha) and its variance (Var(alpha)). Application of this model to experimental measurements of Var(alpha) for a range of alpha values typically below approximately 1 x 10(-6) cm(-1) allows extinction cross-sections for the aerosol particles to be obtained without need for knowledge of the particle number density. Samples of polystyrene spheres with diameters of 400, 500, 600, and 700 nm were used to test the model by comparing extinction cross-sections determined from the experiment with the predictions of Mie theory calculations. Fitting of ring-down decay traces exhibiting amplitude noise to extract cavity ring-down times introduces additional quadratic and higher order polynomial dependencies of the variance that become significant for larger particle number densities and thus extinction coefficients (typically for alpha > 1 x 10(-6) cm(-1) under our experimental conditions). Aggregation of particles at larger number densities is suggested as a further source of variance in the measurements. Extinction cross-sections are severely underestimated if the measurements are made too rapidly to sample uncorrelated distributions of particle numbers and positions.
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Affiliation(s)
- Timothy J A Butler
- School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, United Kingdom
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Lang-Yona N, Rudich Y, Segre E, Dinar E, Abo-Riziq A. Complex Refractive Indices of Aerosols Retrieved by Continuous Wave-Cavity Ring Down Aerosol Spectrometer. Anal Chem 2009; 81:1762-9. [DOI: 10.1021/ac8017789] [Citation(s) in RCA: 81] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- N. Lang-Yona
- Department of Environmental Sciences and Physics Services, Weizmann Institute, Rehovot 76100, Israel
| | - Y. Rudich
- Department of Environmental Sciences and Physics Services, Weizmann Institute, Rehovot 76100, Israel
| | - E. Segre
- Department of Environmental Sciences and Physics Services, Weizmann Institute, Rehovot 76100, Israel
| | - E. Dinar
- Department of Environmental Sciences and Physics Services, Weizmann Institute, Rehovot 76100, Israel
| | - A. Abo-Riziq
- Department of Environmental Sciences and Physics Services, Weizmann Institute, Rehovot 76100, Israel
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27
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Baran SG, Hancock G, Peverall R, Ritchie GAD, van Leeuwen NJ. Optical feedback cavity enhanced absorption spectroscopy with diode lasers. Analyst 2009; 134:243-9. [DOI: 10.1039/b811793d] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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28
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Everest MA, Atkinson DB. Discrete sums for the rapid determination of exponential decay constants. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2008; 79:023108. [PMID: 18315284 DOI: 10.1063/1.2839918] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Several computational methods are presented for the rapid extraction of decay time constants from discrete exponential data. Two methods are found to be comparably fast and highly accurate. They are corrected successive integration and a method involving the Fourier transform (FT) of the data and the application of an expression that does not assume continuous data. FT methods in the literature are found to introduce significant systematic error owing to the assumption that data are continuous. Corrected successive integration methods in the literature are correct, but we offer a more direct way of applying them which we call linear regression of the sum. We recommend the use of the latter over FT-based methods, as the FT methods are more affected by noise in the original data.
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Affiliation(s)
- Michael A Everest
- Department of Biology and Chemistry, George Fox University, 414 N Meridian St., Newberg, Oregon 97132, USA.
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Miller JL, Orr-Ewing AJ. Cavity ring-down spectroscopy measurement of single aerosol particle extinction. II. Extinction of light by an aerosol particle in an optical cavity excited by a cw laser. J Chem Phys 2007; 126:174303. [PMID: 17492859 DOI: 10.1063/1.2723736] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The authors present an analytical derivation of the scattered power from a spherical, homogeneous, nonabsorbing particle in a plane standing wave. The scattered power changes significantly with the position of the particle with respect to the peaks and nodes of the standing wave, even for particles whose diameters are many times the wavelength of the light. The analysis is applicable to continuous-wave cavity ring-down spectroscopy on aerosol particles, and the structure of the standing wave is expected to affect both the measured ring-down time and the shape of the ring-down trace. The dependence of the extinction on the phase of the standing wave at the location of the particle is captured in a parameter zeta which connects the current treatment to standard Mie scattering theory. Methods for calculating zeta are presented.
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Affiliation(s)
- Johanna L Miller
- School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, United Kingdom
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