1
|
Freedman MA, Huang Q, Pitta KR. Phase Transitions in Organic and Organic/Inorganic Aerosol Particles. Annu Rev Phys Chem 2024; 75:257-281. [PMID: 38382569 DOI: 10.1146/annurev-physchem-083122-115909] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/23/2024]
Abstract
The phase state of aerosol particles can impact numerous atmospheric processes, including new particle growth, heterogeneous chemistry, cloud condensation nucleus formation, and ice nucleation. In this article, the phase transitions of inorganic, organic, and organic/inorganic aerosol particles are discussed, with particular focus on liquid-liquid phase separation (LLPS). The physical chemistry that determines whether LLPS occurs, at what relative humidity it occurs, and the resultant particle morphology is explained using both theoretical and experimental methods. The known impacts of LLPS on aerosol processes in the atmosphere are discussed. Finally, potential evidence for LLPS from field and chamber studies is presented. By understanding the physical chemistry of the phase transitions of aerosol particles, we will acquire a better understanding of aerosol processes, which in turn impact human health and climate.
Collapse
Affiliation(s)
- Miriam Arak Freedman
- Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania, USA; ,
- Department of Meteorology and Atmospheric Science, The Pennsylvania State University, University Park, Pennsylvania, USA
| | - Qishen Huang
- Institute of Chemical Physics, School of Chemistry and Chemical Engineering, Beijing Institute of Technology, Beijing, China;
| | - Kiran R Pitta
- Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania, USA; ,
| |
Collapse
|
2
|
Manca M, Zhang C, Scheffold F, Salentinig S. Optical tweezer platform for the characterization of pH-triggered colloidal transformations in the oleic acid/water system. J Colloid Interface Sci 2022; 627:610-620. [PMID: 35872418 DOI: 10.1016/j.jcis.2022.07.028] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2022] [Revised: 06/30/2022] [Accepted: 07/04/2022] [Indexed: 10/17/2022]
Abstract
HYPOTHESIS Soft colloidal particles that respond to their environment have innovative potential for many fields ranging from food and health to biotechnology and oil recovery. The in situ characterisation of colloidal transformations that triggers the functional response remain a challenge. EXPERIMENTS This study demonstrates the combination of an optical micromanipulation platform, polarized optical video microscopy and microfluidics in a comprehensive approach for the analysis of pH-driven structural transformations in emulsions. The new platform, together with synchrotron small angle X-ray scattering, was then applied to research the food-relevant, pH-responsive, oleic acid in water system. FINDINGS The experiments demonstrate structural transformations in individual oleic acid particles from micron-sized onion-type multilamellar oleic acid vesicles at pH 8.6, to nanostructured emulsions at pH < 8.0, and eventually oil droplets at pH < 6.5. The smooth particle-water interface of the onion-type vesicles at pH 8.6 was transformed into a rough particle surface at pH below 7.5. The pH-triggered changes of the interfacial tension at the droplet-water interface together with mass transport owing to structural transformations induced a self-propelled motion of the particle. The results of this study contribute to the fundamental understanding of the structure-property relationship in pH-responsive emulsions for nutrient and drug delivery applications.
Collapse
Affiliation(s)
- Marco Manca
- Department of Chemistry, University of Fribourg, Chemin du Musée 9, 1700 Fribourg, Switzerland
| | - Chi Zhang
- Department of Physics, University of Fribourg, Chemin du Musée 3, 1700 Fribourg, Switzerland
| | - Frank Scheffold
- Department of Physics, University of Fribourg, Chemin du Musée 3, 1700 Fribourg, Switzerland.
| | - Stefan Salentinig
- Department of Chemistry, University of Fribourg, Chemin du Musée 9, 1700 Fribourg, Switzerland.
| |
Collapse
|
3
|
Chang YP, Devi Y, Chen CH. Micro-droplet Trapping and Manipulation: Understanding Aerosol Better for a Healthier Environment. Chem Asian J 2021; 16:1644-1660. [PMID: 33999498 DOI: 10.1002/asia.202100516] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2021] [Indexed: 11/09/2022]
Abstract
Understanding the physicochemical properties and heterogeneous processes of aerosols is key not only to elucidate the impacts of aerosols on the atmosphere and humans but also to exploit their further applications, especially for a healthier environment. Experiments that allow for spatially control of single aerosol particles and investigations on the fundamental properties and heterogeneous chemistry at the single-particle level have flourished during the last few decades, and significant breakthroughs in recent years promise better control and novel applications aimed at resolving key issues in aerosol science. Here we propose graphene oxide (GO) aerosols as prototype aerosols containing polycyclic aromatic hydrocarbons, and GO can behave as two-dimensional surfactants which could modify the interfacial properties of aerosols. We describe the techniques of trapping single particles and furthermore the current status of the optical spectroscopy and chemistry of GO. The current applications of these single-particle trapping techniques are summarized and interesting future applications of GO aerosols are discussed.
Collapse
Affiliation(s)
- Yuan-Pin Chang
- Department of Chemistry, National Sun Yat-sen University, No. 70 Lien-hai Rd., Kaohsiung, 80424, Taiwan.,Aerosol Science Research Center, National Sun Yat-sen University, No. 70 Lien-hai Rd., Kaohsiung, 80424, Taiwan
| | - Yanita Devi
- Department of Chemistry, National Sun Yat-sen University, No. 70 Lien-hai Rd., Kaohsiung, 80424, Taiwan
| | - Chun-Hu Chen
- Department of Chemistry, National Sun Yat-sen University, No. 70 Lien-hai Rd., Kaohsiung, 80424, Taiwan
| |
Collapse
|
4
|
Chang YP, Wu SJ, Lin MS, Chiang CY, Huang GG. Ionic-strength and pH dependent reactivities of ascorbic acid toward ozone in aqueous micro-droplets studied using aerosol optical tweezers. Phys Chem Chem Phys 2021; 23:10108-10117. [PMID: 33876156 DOI: 10.1039/d0cp06493a] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The heterogeneous oxidation reaction of single aqueous ascorbic acid (AH2) aerosol particles with gas-phase ozone was investigated in this study utilizing aerosol optical tweezers with Raman spectroscopy. The measured liquid-phase bimolecular rate coefficients of the AH2 + O3 reaction exhibit a significant pH dependence, and the corresponding values at ionic strength 0.2 M are (3.1 ± 2.0) × 105 M-1 s-1 and (1.2 ± 0.6) × 107 M-1 s-1 for pH ≈ 2 and 6, respectively. These results measured in micron-sized droplets are in agreement with those from previous bulk measurements, indicating that the observed aerosol reaction kinetics can be solely explained by liquid phase diffusion and AH2 + O3 reaction. Furthermore, the results indicate that high ionic strengths could enhance the liquid-phase rate coefficients of the AH2 + O3 reaction. The results also exhibit a negative ozone pressure dependence that can be rationalized in terms of a Langmuir-Hinshelwood type mechanism for the heterogeneous oxidation of AH2 aerosol particles by gas-phase ozone. The results of the present work imply that in acidified airway-lining fluids the antioxidant ability of AH2 against atmospheric ozone will be significantly suppressed.
Collapse
Affiliation(s)
- Yuan-Pin Chang
- Department of Chemistry, National Sun Yat-sen University, Kaohsiung 80424, Taiwan.
| | | | | | | | | |
Collapse
|
5
|
Kalume A, Wang C, Pan YL. Optical-Trapping Laser Techniques for Characterizing Airborne Aerosol Particles and Its Application in Chemical Aerosol Study. MICROMACHINES 2021; 12:466. [PMID: 33924223 PMCID: PMC8074619 DOI: 10.3390/mi12040466] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/31/2021] [Revised: 04/16/2021] [Accepted: 04/16/2021] [Indexed: 11/23/2022]
Abstract
We present a broad assessment on the studies of optically-trapped single airborne aerosol particles, particularly chemical aerosol particles, using laser technologies. To date, extensive works have been conducted on ensembles of aerosols as well as on their analogous bulk samples, and a decent general description of airborne particles has been drawn and accepted. However, substantial discrepancies between observed and expected aerosols behavior have been reported. To fill this gap, single-particle investigation has proved to be a unique intersection leading to a clear representation of microproperties and size-dependent comportment affecting the overall aerosol behavior, under various environmental conditions. In order to achieve this objective, optical-trapping technologies allow holding and manipulating a single aerosol particle, while offering significant advantages such as contactless handling, free from sample collection and preparation, prevention of contamination, versatility to any type of aerosol, and flexibility to accommodation of various analytical systems. We review spectroscopic methods that are based on the light-particle interaction, including elastic light scattering, light absorption (cavity ring-down and photoacoustic spectroscopies), inelastic light scattering and emission (Raman, laser-induced breakdown, and laser-induced fluorescence spectroscopies), and digital holography. Laser technologies offer several benefits such as high speed, high selectivity, high accuracy, and the ability to perform in real-time, in situ. This review, in particular, discusses each method, highlights the advantages and limitations, early breakthroughs, and recent progresses that have contributed to a better understanding of single particles and particle ensembles in general.
Collapse
Affiliation(s)
- Aimable Kalume
- CCDC-US Army Research Laboratory, Adelphi, MD 20783, USA;
| | - Chuji Wang
- Department of Physics and Astronomy, Mississippi State University, Starkville, MS 39759, USA;
| | - Yong-Le Pan
- CCDC-US Army Research Laboratory, Adelphi, MD 20783, USA;
| |
Collapse
|
6
|
Willis MD, Rovelli G, Wilson KR. Combining Mass Spectrometry of Picoliter Samples with a Multicompartment Electrodynamic Trap for Probing the Chemistry of Droplet Arrays. Anal Chem 2020; 92:11943-11952. [PMID: 32786501 DOI: 10.1021/acs.analchem.0c02343] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Single droplet levitation provides contactless access to the microphysical and chemical properties of micrometer-sized samples. Most applications of droplet levitation to chemical and biological systems use nondestructive optical techniques to probe droplet properties. To provide improved chemical specificity, we coupled a multicompartment quadrupole electrodynamic trap (QET) with single droplet mass spectrometry. Our QET continuously traps a monodisperse droplet population (tens to hundreds of droplets) and allows for the simultaneous sizing of a single droplet using its Mie scattering pattern. Single droplets are subsequently ejected into the ionization region of an ambient pressure inlet mass spectrometer. We optimized two complementary soft ionization techniques for picoliter aqueous droplets: (1) paper spray (PS) ionization and (2) thermal desorption glow discharge (TDGD) ionization. Both techniques detect oxygenated organic acids in single droplets, with signal-to-noise ratios >100 and detection limits on the order of 10 pg. Sensitivity and reproducibility across single droplets are driven by the droplet deposition location and spray stability in PS-MS and the ionization region humidity and analyte evaporation rate in TDGD-MS. Importantly, the analyte evaporation rate can control the TDGD-MS quantitative capability because high evaporation rates result in significant ion suppression. This effect is mitigated by optimizing the vaporization temperature, droplet size range, and analyte volatility. We demonstrate quantitative and reproducible measurements with a droplet internal standard (<10% RSD) and compare the sensitivity of PS-MS and TDGD-MS. Finally, we demonstrate the application of QET-MS to the study of heterogeneous chemical kinetics with the reaction of gas phase O3 and aqueous maleic acid droplets.
Collapse
Affiliation(s)
- Megan D Willis
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94720, United States
| | - Grazia Rovelli
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94720, United States
| | - Kevin R Wilson
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94720, United States
| |
Collapse
|
7
|
de Souza Lima R, Braeuer A, Arlabosse P, Ré MI. In situ Raman composition profiling in drying droplets. POWDER TECHNOL 2020. [DOI: 10.1016/j.powtec.2020.05.109] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
|
8
|
Ishizaka S, Guo F, Tian X, Seng S, Tobon YA, Sobanska S. In Situ Observation of Efflorescence and Deliquescence Phase Transitions of Single NaCl and NaNO3 Mixture Particles in Air Using a Laser Trapping Technique. BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN 2020. [DOI: 10.1246/bcsj.20190285] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Shoji Ishizaka
- Department of Chemistry, Graduate School of Science, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8526, Japan
| | - Fangqin Guo
- Department of Chemistry, Graduate School of Science, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8526, Japan
| | - Xiaomeng Tian
- Department of Chemistry, Graduate School of Science, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8526, Japan
| | - Samantha Seng
- Univ. Lille, CNRS, UMR 8516 - LASIR - Laboratoire de Spectrochimie Infrarouge et Raman, F-59000 Lille, France
| | - Yeny A. Tobon
- Univ. Lille, CNRS, UMR 8516 - LASIR - Laboratoire de Spectrochimie Infrarouge et Raman, F-59000 Lille, France
| | - Sophie Sobanska
- Institut des Sciences Moléculaires, CNRS UMR 5255, Université de Bordeaux, 351 Cours de la Libération, 33405 Talence Cedex, France
| |
Collapse
|
9
|
Gorkowski K, Donahue NM, Sullivan RC. Aerosol Optical Tweezers Constrain the Morphology Evolution of Liquid-Liquid Phase-Separated Atmospheric Particles. Chem 2020. [DOI: 10.1016/j.chempr.2019.10.018] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
|
10
|
Enhancing Double-Beam Laser Tweezers Raman Spectroscopy (LTRS) for the Photochemical Study of Individual Airborne Microdroplets. Molecules 2019; 24:molecules24183325. [PMID: 31547361 PMCID: PMC6766935 DOI: 10.3390/molecules24183325] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2019] [Revised: 09/03/2019] [Accepted: 09/05/2019] [Indexed: 11/23/2022] Open
Abstract
A new device and methodology for vertically coupling confocal Raman microscopy with optical tweezers for the in situ physico- and photochemical studies of individual microdroplets (Ø ≤ 10 µm) levitated in air is presented. The coupling expands the spectrum of studies performed with individual particles using laser tweezers Raman spectroscopy (LTRS) to photochemical processes and spatially resolved Raman microspectroscopy on airborne aerosols. This is the first study to demonstrate photochemical studies and Raman mapping on optically levitated droplets. By using this configuration, photochemical reactions in aerosols of atmospheric interest can be studied on a laboratory scale under realistic conditions of gas-phase composition and relative humidity. Likewise, the distribution of photoproducts within the drop can also be observed with this setup. The applicability of the coupling system was tested by studying the photochemical behavior of microdroplets (5 µm < Ø < 8 µm) containing an aqueous solution of sodium nitrate levitated in air and exposed to narrowed UV radiation (254 ± 25 nm). Photolysis of the levitated NaNO3 microdroplets presented photochemical kinetic differences in comparison with larger NaNO3 droplets (40 µm < Ø < 80 µm), previously photolyzed using acoustic traps, and heterogeneity in the distribution of the photoproducts within the drop.
Collapse
|
11
|
Gorkowski K, Donahue NM, Sullivan RC. Emerging investigator series: determination of biphasic core-shell droplet properties using aerosol optical tweezers. ENVIRONMENTAL SCIENCE. PROCESSES & IMPACTS 2018; 20:1512-1523. [PMID: 29897369 DOI: 10.1039/c8em00166a] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
We present a new algorithm for the analysis of whispering gallery modes (WGMs) found in the cavity enhanced Raman spectra retrieved from optically tweezed droplets. Our algorithm improves the computational scaling when analyzing core-shell droplets (i.e. phase-separated or biphasic droplets) in the aerosol optical tweezers (AOT), making it computationally practical to analyze spectra collected at a few Hz over hours-long experiments. This enables the determination of the size and refractive index of both the core and shell phases with high accuracy, at 0.5 Hz time resolution. Phase-separated core-shell droplets are common morphologies in a wide variety of biophysical, colloidal, and aerosolized chemical systems, and have recently become a major focus in understanding the atmospheric chemistry of particulate matter. Our new approach reduces the number of parameters directly searched for, decreasing computational demands. We assess the accuracy of the diameters and refractive indices retrieved from a homogeneous or core-shell droplet. We demonstrate the performance of the new algorithm using experimental data from a droplet of aqueous glycerol coated by squalane. We demonstrate that a shell formation causes adjacent WGMs to split from each other in their wavenumber position through the addition of a secondary organic aerosol shell around a NaCl(aq) droplet. Our new algorithm paves the way for more in-depth physiochemical experiments into liquid-liquid phase separation and their consequences for interfacial chemistry-a topic with growing experimental needs for understanding the dynamics and chemistry of atmospheric aerosol particles, and in biochemical systems.
Collapse
Affiliation(s)
- Kyle Gorkowski
- Center for Atmospheric Particle Studies, Carnegie Mellon University, Pittsburgh, PA, USA.
| | | | | |
Collapse
|
12
|
Lv XJ, Wang Y, Cai C, Pang SF, Ma JB, Zhang YH. Investigation of gel formation and volatilization of acetate acid in magnesium acetate droplets by the optical tweezers. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2018; 200:179-185. [PMID: 29680496 DOI: 10.1016/j.saa.2018.04.027] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/07/2018] [Revised: 04/06/2018] [Accepted: 04/13/2018] [Indexed: 06/08/2023]
Abstract
Hygroscopicity and volatility of single magnesium acetate (MgAc2) aerosol particles at various relative humidities (RHs) are studied by a single-beam optical tweezers, and refractive indices (RIs) and morphology are characterized by cavity enhanced Raman spectroscopy. Gel formation and volatilization of acetate acid (HAc) in MgAc2 droplets are observed. Due to the formation of amorphous gel structure, water transposition in droplets at RH < 50% is significantly impeded on a time scale of 140,000 s. Different phase transition at RH < 10% is proposed to explain the distinct water loss after the gel formation. To compare volatilization of HAc in different systems, MgAc2 and sodium acetate (NaAc) droplets are maintained at several different stable RHs during up to 86,000 s. At RH ≈ 74%, magnesium hydroxide (Mg(OH)2) inclusions are formed in MgAc2 droplets due to the volatilization of HAc, and whispering gallery modes (WGMs) of MgAc2 droplets in the Raman spectrum quench after 50,000 s. In sharp contrast, after 86,000 s at RH ≈ 70%, NaAc droplets are in well-mixed liquid states, containing soluble sodium hydroxide (NaOH). At this state, the RI of NaAc droplet is increased, and the quenching of WGMs is not observable.
Collapse
Affiliation(s)
- Xi-Juan Lv
- The Institute of Chemical Physics, School of Chemistry and Chemical Engineering, Beijing Institute of Technology, Beijing 100081, People's Republic of China
| | - Yang Wang
- The Institute of Chemical Physics, School of Chemistry and Chemical Engineering, Beijing Institute of Technology, Beijing 100081, People's Republic of China
| | - Chen Cai
- The Institute of Chemical Physics, School of Chemistry and Chemical Engineering, Beijing Institute of Technology, Beijing 100081, People's Republic of China
| | - Shu-Feng Pang
- The Institute of Chemical Physics, School of Chemistry and Chemical Engineering, Beijing Institute of Technology, Beijing 100081, People's Republic of China
| | - Jia-Bi Ma
- The Institute of Chemical Physics, School of Chemistry and Chemical Engineering, Beijing Institute of Technology, Beijing 100081, People's Republic of China.
| | - Yun-Hong Zhang
- The Institute of Chemical Physics, School of Chemistry and Chemical Engineering, Beijing Institute of Technology, Beijing 100081, People's Republic of China.
| |
Collapse
|
13
|
Gorkowski K, Donahue NM, Sullivan RC. Emulsified and Liquid-Liquid Phase-Separated States of α-Pinene Secondary Organic Aerosol Determined Using Aerosol Optical Tweezers. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2017; 51:12154-12163. [PMID: 28985066 DOI: 10.1021/acs.est.7b03250] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
We demonstrate the first capture and analysis of secondary organic aerosol (SOA) on a droplet suspended in an aerosol optical tweezers (AOT). We examine three initial chemical systems of aqueous NaCl, aqueous glycerol, and squalane at ∼75% relative humidity. For each system we added α-pinene SOA-generated directly in the AOT chamber-to the trapped droplet. The resulting morphology was always observed to be a core of the original droplet phase surrounded by a shell of the added SOA. We also observed a stable emulsion of SOA particles when added to an aqueous NaCl core phase, in addition to the shell of SOA. The persistence of the emulsified SOA particles suspended in the aqueous core suggests that this metastable state may persist for a significant fraction of the aerosol lifecycle for mixed SOA/aqueous particle systems. We conclude that the α-pinene SOA shell creates no major diffusion limitations for water, glycerol, and squalane core phases under humid conditions. These experimental results support the current prompt-partitioning framework used to describe organic aerosol in most atmospheric chemical transport models and highlight the prominence of core-shell morphologies for SOA on a range of core chemical phases.
Collapse
Affiliation(s)
- Kyle Gorkowski
- Center for Atmospheric Particle Studies, Carnegie Mellon University , Pittsburgh, Pennsylvania 15213, United States
| | - Neil M Donahue
- Center for Atmospheric Particle Studies, Carnegie Mellon University , Pittsburgh, Pennsylvania 15213, United States
| | - Ryan C Sullivan
- Center for Atmospheric Particle Studies, Carnegie Mellon University , Pittsburgh, Pennsylvania 15213, United States
| |
Collapse
|
14
|
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.
Collapse
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
| |
Collapse
|
15
|
Woods E, Hull AW, Tigue ML. Uptake of Pyrene onto Fatty Acid Coated NaCl Aerosol Particles. J Phys Chem A 2016; 120:10160-10168. [PMID: 27991789 DOI: 10.1021/acs.jpca.6b11023] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Photoelectric charging experiments monitor the uptake of pyrene onto NaCl aerosol particles coated with either oleic acid or myristic acid. In both cases, thin coatings produce a small net decrease in pyrene uptake. In the larger coverage limit, the uptake of the myristic acid coated particles remains nearly constant whereas the oleic acid coated particles exhibit greater uptake rates than the bare NaCl particles. Fitting the results with a multilayer kinetic model yields uptake rate coefficients as well as parameters that describe the distribution of organic molecules on the aerosol particle surface. The model accounts for the decrease in uptake associated with thin coatings of oleic acid through a concomitant reduction in surface area. The adsorption rate constants for the myristic and oleic acid coated surfaces are 50 and 80 times faster, respectively, than for NaCl. The desorption rates for pyrene on the fatty acid surfaces are faster, as well. For myristic acid coatings, the fast desorption (over 400 times the rate of desorption from NaCl) results in slower net adsorption, whereas for oleic acid (approximately 12 times the desorption rate from NaCl), the net uptake rate increases with coverage. The results also suggest that both myristic acid and oleic acid spread incompletely on the aerosol surfaces under the conditions of these experiments. In the optimized kinetic model, the fatty acids cover approximately 50% of the surface when the nominal coating thickness is approximately 6 nm. The surface is over 90% covered with a nominal coating thickness of 20 nm, which is approximately 10% of particle diameter in these experiments. Very thin oleic acid coatings reduce the surface area of particles consistent with the preferential coverage of highly corrugated or porous regions.
Collapse
Affiliation(s)
- Ephraim Woods
- Department of Chemistry, Colgate University , Hamilton, New York 13346, United States
| | - Alexander W Hull
- Department of Chemistry, Colgate University , Hamilton, New York 13346, United States
| | - Megan L Tigue
- Department of Chemistry, Colgate University , Hamilton, New York 13346, United States
| |
Collapse
|
16
|
Lovrić J, Duflot D, Monnerville M, Toubin C, Briquez S. Water-Induced Organization of Palmitic Acid at the Surface of a Model Sea Salt Particle: A Molecular Dynamics Study. J Phys Chem A 2016; 120:10141-10149. [DOI: 10.1021/acs.jpca.6b07792] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Josip Lovrić
- Laboratoire de
Physique des Lasers, Atomes et Molécules (PhLAM) CNRS, UMR
8523, Univ. Lille, F-59000 Lille, France
| | - Denis Duflot
- Laboratoire de
Physique des Lasers, Atomes et Molécules (PhLAM) CNRS, UMR
8523, Univ. Lille, F-59000 Lille, France
| | - Maurice Monnerville
- Laboratoire de
Physique des Lasers, Atomes et Molécules (PhLAM) CNRS, UMR
8523, Univ. Lille, F-59000 Lille, France
| | - Céline Toubin
- Laboratoire de
Physique des Lasers, Atomes et Molécules (PhLAM) CNRS, UMR
8523, Univ. Lille, F-59000 Lille, France
| | - Stéphane Briquez
- Laboratoire de
Physique des Lasers, Atomes et Molécules (PhLAM) CNRS, UMR
8523, Univ. Lille, F-59000 Lille, France
| |
Collapse
|
17
|
Chapleski RC, Zhang Y, Troya D, Morris JR. Heterogeneous chemistry and reaction dynamics of the atmospheric oxidants, O3, NO3, and OH, on organic surfaces. Chem Soc Rev 2016; 45:3731-46. [DOI: 10.1039/c5cs00375j] [Citation(s) in RCA: 75] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Heterogeneous chemistry of the most important atmospheric oxidants, O3, NO3, and OH, plays a central role in regulating atmospheric gas concentrations, processing aerosols, and aging materials.
Collapse
Affiliation(s)
| | - Yafen Zhang
- Department of Chemistry
- Virginia Tech
- Blacksburg
- USA
| | - Diego Troya
- Department of Chemistry
- Virginia Tech
- Blacksburg
- USA
| | | |
Collapse
|
18
|
Hygroscopicity of Mixed Glycerol/Mg(NO3)2/Water Droplets Affected by the Interaction between Magnesium Ions and Glycerol Molecules. J Phys Chem B 2015; 119:5558-66. [PMID: 25860879 DOI: 10.1021/acs.jpcb.5b00458] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Tropospheric aerosols are usually complex mixtures of inorganic and organic components, which can influence the hygroscopicities of each other. In this research, we applied confocal Raman technology combined with optical microscopy to investigate the relationship between the hygroscopic behavior and the molecular interactions of mixed glycerol/Mg(NO3)2/water droplets. Raman spectra provide detailed structural information about the interactions between glycerol molecules and Mg(2+) ions, as well as information about the interactions between glycerol and NO3(-) ions through electrostatic interaction and hydrogen bonding. The change of the CH2 stretching band of glycerol molecules in mixed droplets suggests that the backbone structures of glycerol mainly transform from αα to γγ in the dehumidifying process, and the additional Mg(2+) ions strongly influence the structure of glycerol molecules. Because the existence of glycerol suppresses the crystallization of Mg(NO3)2·6H2O in the dehumidifying process, Mg(NO3)2 molecules in mixed droplets form an amorphous state rather than forming crystals of Mg(NO3)2·6H2O when the relative humidity is lower than 17.8%. Moreover, in mixed droplets, the molar ratio of NO3(-) to glycerol is higher in the center than in the outer region.
Collapse
|
19
|
Jones SH, King MD, Ward AD. Atmospherically relevant core–shell aerosol studied using optical trapping and Mie scattering. Chem Commun (Camb) 2015; 51:4914-7. [DOI: 10.1039/c4cc09835h] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Solid core–liquid shell aerosols have been trapped in a counter-propagating optical trap confirming potential core–shell morphology in the atmosphere.
Collapse
Affiliation(s)
- S. H. Jones
- Central Laser Facility
- Research Complex at Harwell
- Rutherford Appleton Laboratory
- Didcot
- UK
| | - M. D. King
- Department of Earth Sciences
- Royal Holloway University of London
- Egham
- UK
| | - A. D. Ward
- Central Laser Facility
- Research Complex at Harwell
- Rutherford Appleton Laboratory
- Didcot
- UK
| |
Collapse
|
20
|
Mendez M, Visez N, Gosselin S, Crenn V, Riffault V, Petitprez D. Reactive and Nonreactive Ozone Uptake during Aging of Oleic Acid Particles. J Phys Chem A 2014; 118:9471-81. [DOI: 10.1021/jp503572c] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Maxence Mendez
- Physicochimie
des Processus de Combustion et de l’Atmosphère PC2A, UMR 8522 CNRS/Lille 1, Villeneuve d’Ascq, F-59655, France
| | - Nicolas Visez
- Physicochimie
des Processus de Combustion et de l’Atmosphère PC2A, UMR 8522 CNRS/Lille 1, Villeneuve d’Ascq, F-59655, France
| | - Sylvie Gosselin
- Physicochimie
des Processus de Combustion et de l’Atmosphère PC2A, UMR 8522 CNRS/Lille 1, Villeneuve d’Ascq, F-59655, France
| | - Vincent Crenn
- Sciences
de l’Atmosphère et Génie de l’Environnement, Ecole Nationale Supérieure des Mines de Douai, Douai, F-59508, France
| | - Veronique Riffault
- Sciences
de l’Atmosphère et Génie de l’Environnement, Ecole Nationale Supérieure des Mines de Douai, Douai, F-59508, France
| | - Denis Petitprez
- Physicochimie
des Processus de Combustion et de l’Atmosphère PC2A, UMR 8522 CNRS/Lille 1, Villeneuve d’Ascq, F-59655, France
| |
Collapse
|
21
|
Lu JW, Isenor M, Chasovskikh E, Stapfer D, Signorell R. Low-temperature Bessel beam trap for single submicrometer aerosol particle studies. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2014; 85:095107. [PMID: 25273772 DOI: 10.1063/1.4895118] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2014] [Accepted: 08/27/2014] [Indexed: 06/03/2023]
Abstract
We report on a new instrument for single aerosol particle studies at low temperatures that combines an optical trap consisting of two counter-propagating Bessel beams (CPBBs) and temperature control down to 223 K (-50 °C). The apparatus is capable of capturing and stably trapping individual submicrometer- to micrometer-sized aerosol particles for up to several hours. First results from studies of hexadecane, dodecane, and water aerosols reveal that we can trap and freeze supercooled droplets ranging in size from ~450 nm to 5500 nm (radius). We have conducted homogeneous and heterogeneous freezing experiments, freezing-melting cycles, and evaporation studies. To our knowledge, this is the first reported observation of the freezing process for levitated single submicrometer-sized droplets in air using optical trapping techniques. These results show that a temperature-controlled CPBB trap is an attractive new method for studying phase transitions of individual submicrometer aerosol particles.
Collapse
Affiliation(s)
- Jessica W Lu
- Laboratory of Physical Chemistry, ETH Zürich, Vladimir-Prelog-Weg 2, CH-8093 Zürich, Switzerland
| | - Merrill Isenor
- 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
| | - David Stapfer
- 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
| |
Collapse
|
22
|
Dennis-Smither BJ, Marshall FH, Miles REH, Preston TC, Reid JP. Volatility and Oxidative Aging of Aqueous Maleic Acid Aerosol Droplets and the Dependence on Relative Humidity. J Phys Chem A 2014; 118:5680-91. [DOI: 10.1021/jp504823j] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Affiliation(s)
| | | | | | | | - Jonathan P. Reid
- School of Chemistry, University of Bristol, Bristol BS8 1TS, U.K
| |
Collapse
|
23
|
Power RM, Reid JP. Probing the micro-rheological properties of aerosol particles using optical tweezers. REPORTS ON PROGRESS IN PHYSICS. PHYSICAL SOCIETY (GREAT BRITAIN) 2014; 77:074601. [PMID: 24994710 DOI: 10.1088/0034-4885/77/7/074601] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
The use of optical trapping techniques to manipulate probe particles for performing micro-rheological measurements on a surrounding fluid is well-established. Here, we review recent advances made in the use of optical trapping to probe the rheological properties of trapped particles themselves. In particular, we review observations of the continuous transition from liquid to solid-like viscosity of sub-picolitre supersaturated solution aerosol droplets using optical trapping techniques. Direct measurements of the viscosity of the particle bulk are derived from the damped oscillations in shape following coalescence of two particles, a consequence of the interplay between viscous and surface forces and the capillary driven relaxation of the approximately spheroidal composite particle. Holographic optical tweezers provide a facile method for the manipulation of arrays of particles allowing coalescence to be controllably induced between two micron-sized aerosol particles. The optical forces, while sufficiently strong to confine the composite particle, are several orders of magnitude weaker than the capillary forces driving relaxation. Light, elastically back-scattered by the particle, is recorded with sub-100 ns resolution allowing measurements of fast relaxation (low viscosity) dynamics, while the brightfield image can be used to monitor the shape relaxation extending to times in excess of 1000 s. For the slowest relaxation dynamics studied (particles with the highest viscosity) the presence and line shape of whispering gallery modes in the cavity enhanced Raman spectrum can be used to infer the relaxation time while serving the dual purpose of allowing the droplet size and refractive index to be measured with accuracies of ±0.025% and ±0.1%, respectively. The time constant for the damped relaxation can be used to infer the bulk viscosity, spanning from the dilute solution limit to a value approaching that of a glass, typically considered to be >10(12) Pa s, whilst the frequencies of the normal modes of the oscillations of the particle can be used to infer surface properties. We will review the use of optical tweezers for studying the viscosity of aerosol particles and discuss the potential use of this micro-rheological tool for probing the fundamental concepts of phase, thermodynamic equilibrium and metastability.
Collapse
Affiliation(s)
- Rory M Power
- School of Chemistry, University of Bristol, Bristol, BS8 1TS, UK
| | | |
Collapse
|
24
|
Zhou Q, Pang SF, Wang Y, Ma JB, Zhang YH. Confocal Raman Studies of the Evolution of the Physical State of Mixed Phthalic Acid/Ammonium Sulfate Aerosol Droplets and the Effect of Substrates. J Phys Chem B 2014; 118:6198-205. [DOI: 10.1021/jp5004598] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Qiang Zhou
- The Institute of Chemical
Physics, Key Laboratory of Cluster Science, School of Chemistry, Beijing Institute of Technology, Beijing 100081, People’s Republic of China
| | - Shu-Feng Pang
- The Institute of Chemical
Physics, Key Laboratory of Cluster Science, School of Chemistry, Beijing Institute of Technology, Beijing 100081, People’s Republic of China
| | - Yang Wang
- The Institute of Chemical
Physics, Key Laboratory of Cluster Science, School of Chemistry, Beijing Institute of Technology, Beijing 100081, People’s Republic of China
| | - Jia-Bi Ma
- The Institute of Chemical
Physics, Key Laboratory of Cluster Science, School of Chemistry, Beijing Institute of Technology, Beijing 100081, People’s Republic of China
| | - Yun-Hong Zhang
- The Institute of Chemical
Physics, Key Laboratory of Cluster Science, School of Chemistry, Beijing Institute of Technology, Beijing 100081, People’s Republic of China
| |
Collapse
|
25
|
Cotterell MI, Mason BJ, Carruthers AE, Walker JS, Orr-Ewing AJ, Reid JP. Measurements of the evaporation and hygroscopic response of single fine-mode aerosol particles using a Bessel beam optical trap. Phys Chem Chem Phys 2014; 16:2118-28. [DOI: 10.1039/c3cp54368d] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
|
26
|
Rickards AMJ, Miles REH, Davies JF, Marshall FH, Reid JP. Measurements of the Sensitivity of Aerosol Hygroscopicity and the κ Parameter to the O/C Ratio. J Phys Chem A 2013; 117:14120-31. [DOI: 10.1021/jp407991n] [Citation(s) in RCA: 78] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Affiliation(s)
| | | | - James F. Davies
- 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
| |
Collapse
|
27
|
Robinson CB, Schill GP, Zarzana KJ, Tolbert MA. Impact of organic coating on optical growth of ammonium sulfate particles. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2013; 47:13339-13346. [PMID: 24144443 DOI: 10.1021/es4023128] [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
Light extinction by particles in Earth's atmosphere is strongly dependent on particle size, chemical composition, hygroscopic growth properties, and particle mixing state. Here, the influence of an organic coating on particle optical growth was studied. The particle optical growth factor, fRHext, was measured using cavity ring-down aerosol extinction spectroscopy at 532 nm. The particles were composed of ammonium sulfate (AS), 1,2,6-hexanetriol, and mixed particles containing a wet or dry ammonium sulfate core and a 1,2,6-hexanetriol coating. Dry, coated particles were generated by atomization followed by drying. Wet, coated particles were formed via liquid-liquid phase separation (LLPS). LLPS was achieved by deliquescing and then drying the particles to a relative humidity (RH) between the phase separation RH and the efflorescence RH. For the LLPS particles, the fRHext at each RH was between the fRHext of ammonium sulfate and that of 1,2,6-hexanetriol. In contrast, for the mixed dry, coated particles, the fRHext was the same as 1,2,6-hexanetriol particles. At room temperature, the water uptake properties of AS coated with 1,2,6-hexanetriol are largely dictated by the phase of the AS. Thus, the total water uptake depends on the RH history of the particle and the resulting phase of AS.
Collapse
Affiliation(s)
- Carly B Robinson
- Department of Chemistry and Biochemistry and ‡Cooperative Institute for Research in Environmental Sciences (CIRES), University of Colorado at Boulder , Boulder, Colorado 80309-0216, United States
| | | | | | | |
Collapse
|
28
|
Haddrell AE, Hargreaves G, Davies JF, Reid JP. Control over hygroscopic growth of saline aqueous aerosol using Pluronic polymer additives. Int J Pharm 2013; 443:183-92. [PMID: 23333755 DOI: 10.1016/j.ijpharm.2012.12.039] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2012] [Revised: 12/19/2012] [Accepted: 12/20/2012] [Indexed: 11/30/2022]
Abstract
The hygroscopic properties of an aerosol originating from a nebulizer solution can affect the extent of peripheral deposition within the respiratory tract, which in turn affects drug efficacy of drugs delivered to the lungs. Thus, the ability to tailor the degree and rate of hygroscopic growth of an aerosol produced by a nebulizer through modification of the formulation would serve to improve drug efficacy through targeted lung deposition. In this study, the kinetic and thermodynamic hygroscopic properties of sodium chloride aerosol mixed with commercially available Pluronic polymers, specifically F77 and F127, are reported using three complementary single aerosol analysis techniques, specifically aerosol optical tweezers, a double ring electrodynamic balance and a concentric cylinder electrodynamic balance. The F77 polymer is shown to have a predictable effect on the hygroscopic properties of the aerosol: the ability of the droplet to uptake water from the air depends on the solute weight percent of sodium chloride present in a linear dose dependant manner. Unlike the smaller F77, a non-linear relationship was observed for the larger molecular weight F127 polymer, with significant suppression of hygroscopic growth (>50% by mass) for solution aerosol containing even only 1 wt% of the polymer and 99 wt% sodium chloride. The suppression of growth is shown to be consistent with the formation of mixed phase aerosol particles containing hydrophilic inorganic rich domains and hydrophobic polymer rich domains that sequester some of the inorganic component, with the two phases responding to changes in relative humidity independently. This independence of coupling with the gas phase is apparent in both the equilibrium state and the kinetics of water evaporation/condensation. By starting with a saline nebulizer solution with a concentration of F127 ∼10(-2)mM, a 12% reduction in the radius of all aerosol produced at a relative humidity (RH) of 84% is possible. The difference in diameter is RH dependent, and may be much greater at higher humidities. These findings suggest that the addition of μM concentrations of larger Pluronic polymers to nebulizer formulations may greatly reduce the size of aerosols produced.
Collapse
|
29
|
Dilbeck CW, Finlayson-Pitts BJ. Heterogeneous oxidation of a phosphocholine on synthetic sea salt by ozone at room temperature. Phys Chem Chem Phys 2012; 15:1990-2002. [PMID: 23258195 DOI: 10.1039/c2cp43665e] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
The ozonolysis of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) adsorbed on salt mixtures as models for sea-salt particles was studied in real time using diffuse reflection infrared Fourier transform spectrometry (DRIFTS) at room temperature with and without added water vapor. The salt substrates were a mixture of MgCl(2)·6H(2)O with NaCl or a commercially available synthetic sea salt. Ozone concentrations ranged from (0.25 to 3.9) × 10(13) molecules cm(-3) (0.1-1.6 ppm). The major products identified by FTIR and confirmed using matrix-assisted laser desorption/ionization (MALDI) mass spectrometry were the secondary ozonide (SOZ) and a phospholipid aldehyde and carboxylic acid formed by scission of the double bond. The reaction probabilities for the two substrates were similar, γ = (6-7) × 10(-7), with an estimated overall uncertainty of a factor of two. The presence of water vapor decreased the yield of SOZ relative to the products formed by C[double bond, length as m-dash]C scission, but also increased the availability of the double bond for reaction, particularly on the less hygroscopic commercial sea-salt substrate. Thus, water not only affects the mechanisms and products, but also the structure of the phospholipid on the salt in a manner that affects its reactivity. The results of these studies suggest that the reactivity and products of oxidation of unsaturated phospholipids on sea-salt particles in air will be very sensitive to the nature and phase of the substrate, the amount of water present, and whether there is phase separation between the organics and the inorganic salt mixture.
Collapse
Affiliation(s)
- Christopher W Dilbeck
- Department of Chemistry, University of California Irvine, Irvine, CA 92697-2025, USA
| | | |
Collapse
|
30
|
Dennis-Smither BJ, Miles REH, Reid JP. Oxidative aging of mixed oleic acid/sodium chloride aerosol particles. ACTA ACUST UNITED AC 2012. [DOI: 10.1029/2012jd018163] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
|