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Kohli RK, Davies JF. Measuring the Chemical Evolution of Levitated Particles: A Study on the Evaporation of Multicomponent Organic Aerosol. Anal Chem 2021; 93:12472-12479. [PMID: 34455787 DOI: 10.1021/acs.analchem.1c02890] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Single-particle levitation methods provide an effective platform for probing the physical properties of atmospheric aerosol via micrometer-sized particles. Until recently, chemical composition measurements on levitated particles were limited to spectroscopy, yielding only basic chemical information. Here, we describe, benchmark, and discuss the applications of an approach for probing the physical properties and chemical composition of single levitated particles using high-resolution mass spectrometry (MS). Using a linear quadrupole electrodynamic balance (LQ-EDB) coupled to paper spray mass spectrometry, we report accurate measurements of the evolving size within 5 nm (using broadband light scattering) and relative composition (using MS) of evaporating multicomponent levitated particles in real time. Measurements of the evaporation dynamics of semivolatile organic particles containing a range of n-ethylene glycols (n = 3, 4, and 6) in various binary and ternary mixtures were made under dry conditions and compared with predictions from a gas-phase diffusion evaporation model. Under assumptions of ideal mixing, excellent agreement for both size and composition evolution between measurements and models were obtained for these mixtures. At increased relative humidity, the presence of water in particles causes the assumption of ideality to break down, and the evaporative mass flux becomes a function of the mole fraction and activity coefficient. Through compositionally resolved evaporation measurements and thermodynamic models, we characterize the activity of organic components in multicomponent particles. Our results demonstrate that the LQ-EDB-MS platform can identify time-dependent size and compositional changes with high precision and reproducibility, yielding an effective methodology for future studies on chemical aging and gas-particle partitioning in suspended particles.
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Affiliation(s)
- Ravleen Kaur Kohli
- Department of Chemistry, University of California, Riverside, California 92521, United States
| | - James F Davies
- Department of Chemistry, University of California, Riverside, California 92521, United States
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2
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Boyer HC, Gorkowski K, Sullivan RC. In Situ pH Measurements of Individual Levitated Microdroplets Using Aerosol Optical Tweezers. Anal Chem 2020; 92:1089-1096. [PMID: 31760745 DOI: 10.1021/acs.analchem.9b04152] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
The pH of microscale reaction environments controls numerous physicochemical processes, requiring a real-time pH microprobe. We present highly accurate real-time pH measurements of microdroplets using aerosol optical tweezers (AOT) and analysis of the whispering gallery modes (WGMs) contained in the cavity-enhanced Raman spectra. Uncertainties ranging from ±0.03 to 0.06 in pH for picoliter droplets are obtained through averaging Raman frames acquired at 0.5 Hz over 3.3 min. The high accuracy in pH determination is achieved by combining two independent measurements uniquely provided by the AOT approach: the anion concentration ratio from the spontaneous Raman spectra, and the total solute concentration from the refractive index retrieved from WGM analysis of the stimulated cavity-enhanced Raman spectra. pH can be determined over a range of -0.36 to 0.76 using the aqueous sodium bisulfate system. This technique enables direct measurements of pH-dependent chemical and physical changes experienced by individual microparticles and exploration of the role of pH in the chemical behavior of confined microenvironments.
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Affiliation(s)
- Hallie C Boyer
- Center for Atmospheric Particle Studies , Carnegie Mellon University , Pittsburgh , Pennsylvania 15213 , United States
| | - Kyle Gorkowski
- Department of Atmospheric and Oceanic Sciences , McGill University , Montreal , Quebec H3A 0B9 , Canada
| | - Ryan C Sullivan
- Center for Atmospheric Particle Studies , Carnegie Mellon University , Pittsburgh , Pennsylvania 15213 , United States
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3
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Bzdek BR, Reid JP. Perspective: Aerosol microphysics: From molecules to the chemical physics of aerosols. J Chem Phys 2017; 147:220901. [DOI: 10.1063/1.5002641] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Affiliation(s)
- Bryan R. Bzdek
- 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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4
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Bzdek BR, Collard L, Sprittles JE, Hudson AJ, Reid JP. Dynamic measurements and simulations of airborne picolitre-droplet coalescence in holographic optical tweezers. J Chem Phys 2017; 145:054502. [PMID: 27497560 DOI: 10.1063/1.4959901] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
We report studies of the coalescence of pairs of picolitre aerosol droplets manipulated with holographic optical tweezers, probing the shape relaxation dynamics following coalescence by simultaneously monitoring the intensity of elastic backscattered light (EBL) from the trapping laser beam (time resolution on the order of 100 ns) while recording high frame rate camera images (time resolution <10 μs). The goals of this work are to: resolve the dynamics of droplet coalescence in holographic optical traps; assign the origin of key features in the time-dependent EBL intensity; and validate the use of the EBL alone to precisely determine droplet surface tension and viscosity. For low viscosity droplets, two sequential processes are evident: binary coalescence first results from the overlap of the optical traps on the time scale of microseconds followed by the recapture of the composite droplet in an optical trap on the time scale of milliseconds. As droplet viscosity increases, the relaxation in droplet shape eventually occurs on the same time scale as recapture, resulting in a convoluted evolution of the EBL intensity that inhibits quantitative determination of the relaxation time scale. Droplet coalescence was simulated using a computational framework to validate both experimental approaches. The results indicate that time-dependent monitoring of droplet shape from the EBL intensity allows for robust determination of properties such as surface tension and viscosity. Finally, the potential of high frame rate imaging to examine the coalescence of dissimilar viscosity droplets is discussed.
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Affiliation(s)
- Bryan R Bzdek
- School of Chemistry, University of Bristol, Bristol BS8 1TS, United Kingdom
| | - Liam Collard
- Department of Mathematics, University of Leicester, Leicester LE1 7RH, United Kingdom
| | - James E Sprittles
- Mathematics Institute, University of Warwick, Coventry CV4 7AL, United Kingdom
| | - Andrew J Hudson
- Department of Chemistry, University of Leicester, Leicester LE1 7RH, United Kingdom
| | - Jonathan P Reid
- School of Chemistry, University of Bristol, Bristol BS8 1TS, United Kingdom
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Boyer HC, Bzdek BR, Reid JP, Dutcher CS. Statistical Thermodynamic Model for Surface Tension of Organic and Inorganic Aqueous Mixtures. J Phys Chem A 2016; 121:198-205. [DOI: 10.1021/acs.jpca.6b10057] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Hallie C. Boyer
- Department
of Mechanical Engineering, University of Minnesota, Twin Cities, Minneapolis, Minnesota 55455, United States
| | - Bryan R. Bzdek
- 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
| | - Cari S. Dutcher
- Department
of Mechanical Engineering, University of Minnesota, Twin Cities, Minneapolis, Minnesota 55455, United States
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6
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Park H, LeBrun TW. Contact Electrification of Individual Dielectric Microparticles Measured by Optical Tweezers in Air. ACS APPLIED MATERIALS & INTERFACES 2016; 8:34904-34913. [PMID: 27936542 DOI: 10.1021/acsami.6b12603] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
We measure charging of single dielectric microparticles after interaction with a glass substrate using optical tweezers to control the particle, measure its charge with a sensitivity of a few electrons, and precisely contact the particle with the substrate. Polystyrene (PS) microparticles adhered to the substrate can be selected based on size, shape, or optical properties and repeatedly loaded into the optical trap using a piezoelectric (PZT) transducer. Separation from the substrate leads to charge transfer through contact electrification. The charge on the trapped microparticles is measured from the response of the particle motion to a step excitation of a uniform electric field. The particle is then placed onto a target location of the substrate in a controlled manner. Thus, the triboelectric charging profile of the selected PS microparticle can be measured and controlled through repeated cycles of trap loading followed by charge measurement. Reversible optical trap loading and manipulation of the selected particle leads to new capabilities to study and control successive and small changes in surface interactions.
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Affiliation(s)
- Haesung Park
- Physical Measurement Laboratory, National Institute of Standards and Technology , Gaithersburg, Maryland 20899, United States
| | - Thomas W LeBrun
- Physical Measurement Laboratory, National Institute of Standards and Technology , Gaithersburg, Maryland 20899, United States
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Tang M, Cziczo DJ, Grassian VH. Interactions of Water with Mineral Dust Aerosol: Water Adsorption, Hygroscopicity, Cloud Condensation, and Ice Nucleation. Chem Rev 2016; 116:4205-59. [DOI: 10.1021/acs.chemrev.5b00529] [Citation(s) in RCA: 228] [Impact Index Per Article: 28.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Mingjin Tang
- Department
of Chemistry, University of Iowa, Iowa City, Iowa 52242, United States
| | - Daniel J. Cziczo
- Department
of Earth, Atmospheric and Planetary Sciences and Civil and Environmental
Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Vicki H. Grassian
- Department
of Chemistry, University of Iowa, Iowa City, Iowa 52242, United States
- Departments
of Chemistry and Biochemistry, Nanoengineering and Scripps Institution
of Oceanography, University of California San Diego, La Jolla, California 92093, United States
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8
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Bzdek BR, Power RM, Simpson SH, Reid JP, Royall CP. Precise, contactless measurements of the surface tension of picolitre aerosol droplets. Chem Sci 2015; 7:274-285. [PMID: 28758004 PMCID: PMC5515047 DOI: 10.1039/c5sc03184b] [Citation(s) in RCA: 71] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2015] [Accepted: 10/02/2015] [Indexed: 01/25/2023] Open
Abstract
Precise measurements of the surface tension and viscosity of airborne picolitre droplets can be accomplished using holographic optical tweezers.
The surface composition and surface tension of aqueous droplets can influence key aerosol characteristics and processes including the critical supersaturation required for activation to form cloud droplets in the atmosphere. Despite its fundamental importance, surface tension measurements on droplets represent a considerable challenge owing to their small volumes. In this work, we utilize holographic optical tweezers to study the damped surface oscillations of a suspended droplet (<10 μm radius) following the controlled coalescence of a pair of droplets and report the first contactless measurements of the surface tension and viscosity of droplets containing only 1–4 pL of material. An advantage of performing the measurement in aerosol is that supersaturated solute states (common in atmospheric aerosol) may be accessed. For pairs of droplets starting at their equilibrium surface composition, surface tensions and viscosities are consistent with bulk equilibrium values, indicating that droplet surfaces respond to changes in surface area on microsecond timescales and suggesting that equilibrium values can be assumed for growing atmospheric droplets. Furthermore, droplet surfaces are shown to be rapidly modified by trace species thereby altering their surface tension. This equilibration of droplet surface tension to the local environmental conditions is illustrated for unknown contaminants in laboratory air and also for droplets exposed to gas passing through a water–ethanol solution. This approach enables precise measurements of surface tension and viscosity over long time periods, properties that currently are poorly constrained.
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Affiliation(s)
- Bryan R Bzdek
- School of Chemistry , University of Bristol , Bristol , BS8 1TS , UK .
| | - Rory M Power
- School of Chemistry , University of Bristol , Bristol , BS8 1TS , UK . .,Max Planck Institute of Molecular Cell Biology and Genetics , Dresden , 01307 , Germany
| | - Stephen H Simpson
- School of Chemistry , University of Bristol , Bristol , BS8 1TS , UK . .,Institute of Scientific Instruments of the ASCR. v.v.i. , Krávolopolská 147 , 612 64 , Brno , Czech Republic
| | - Jonathan P Reid
- School of Chemistry , University of Bristol , Bristol , BS8 1TS , UK .
| | - C Patrick Royall
- School of Chemistry , University of Bristol , Bristol , BS8 1TS , UK . .,H. H. Wills Physics Laboratory , University of Bristol , Bristol , BS8 1TL , UK.,Centre for Nanoscience and Quantum Information , University of Bristol , BS8 1FD , UK
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David G, Esat K, Hartweg S, Cremer J, Chasovskikh E, Signorell R. Stability of aerosol droplets in Bessel beam optical traps under constant and pulsed external forces. J Chem Phys 2015; 142:154506. [DOI: 10.1063/1.4917202] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Grégory David
- Laboratory of Physical Chemistry, ETH Zürich, Vladimir-Prelog-Weg 2, CH-8093 Zürich, Switzerland
| | - Kıvanç Esat
- Laboratory of Physical Chemistry, ETH Zürich, Vladimir-Prelog-Weg 2, CH-8093 Zürich, Switzerland
| | - Sebastian Hartweg
- Laboratory of Physical Chemistry, ETH Zürich, Vladimir-Prelog-Weg 2, CH-8093 Zürich, Switzerland
| | - Johannes Cremer
- Laboratory of Physical Chemistry, ETH Zürich, Vladimir-Prelog-Weg 2, CH-8093 Zürich, Switzerland
| | - Egor Chasovskikh
- Laboratory of Physical Chemistry, ETH Zürich, Vladimir-Prelog-Weg 2, CH-8093 Zürich, Switzerland
| | - Ruth Signorell
- Laboratory of Physical Chemistry, ETH Zürich, Vladimir-Prelog-Weg 2, CH-8093 Zürich, Switzerland
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