Morphology And Optical Properties Of Aerosol Particles

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Morphology and Optical Properties of Aerosol Particles

Author : Daniel Veghte
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (915 download)

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Book Synopsis Morphology and Optical Properties of Aerosol Particles by : Daniel Veghte

Download or read book Morphology and Optical Properties of Aerosol Particles written by Daniel Veghte and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Major factors that affect climate change depend on gas and particulate phase components in the atmosphere. Gas phase species have been studied in great detail and are well understood, causing a warming effect on the atmosphere. The less understood major contributing factor in the atmosphere are aerosol particles, which range in size from nanometers up to microns. Aerosol particles can directly scatter and absorb light and also have secondary effects such as acting as a surface for gas phase reactions to occur or seed particles for cloud formation. Aerosol particles can cause health problems ranging from serious cardiovascular to respiratory effects. All Climate and health effects of aerosol particles are dependent on particle composition, morphology, concentration, and size. Since a large variety of particulate types exist in the atmosphere, we have focused on understanding the effect of mineral dust composition and morphology. Mineral dust is important because it is the second largest emission by mass. In order to study the optical properties of aerosol particles, we built a cavity ring-down spectrometer and developed methods to interpret the excinction cross section results for particles with a varied shape. We have studied the major components of mineral dust that include calcium carbonate, hematite, quartz, aluminosilicate clay minerals, and feldspars, along with a heterogeneous dust sample. We have found that non-absorbing species that have surface roughness and an aspect ratio close to one (such as calcite, quartz and feldspar) can be treated as spheres. Aerosol particles that are absorbing (hematite) that have an aspect ratio near one with a roughened surface need to be treated with more complex models; otherwise the extinction cross section will be underrepresented. For aerosol particles that are non-absorbing but have a high aspect ratio (aluminosilicate clay minerals), additional modeling parameters are also needed that will account for shape and orientation. We have used Arizona Test Dust to determine if the models we have developed can be used to model the optical properties of a heterogeneous mixture. We have shown that the extinction cross section of the Arizona Test Dust can be modeled as long as individual components are treated independently and significant error would be introduces if all species were treated as spheres.Organic aerosol particles are chemically complex species that originate from primary or secondary emissions. We have described mixed organic/ammonium sulfate particles in the submicron regime using TEM to understand phase separation. When the organic component has a high aqueous solubility, all particles exhibit a homogeneous morphology while at low aqueous solubility all particles exhibit a phase separated structure. Intermediate solubility organics show a size dependent morphology. For pimelic and succinic acid, small particles (under approximately 200 nm) have a homogeneous structure while the larger particles exhibit phase separated structures. We have studied samples collected in Ulaanbaatar, Mongolia to better understand the types of particles and the effect of aging on these particles in an urban environment. The majority of the particles are soot, small spheres, or mineral dust. When we compared the monthly particle composition, we saw that there was an increased aging of the particles during the winter months due to pollution and a lower boundary layer leading to reduced atmospheric mixing. By understanding the particle composition present in areas and modeling the optical properties of individual particle types, better models can be created to give insight into aerosol particles affects on the atmosphere.

Morphology and Optical Properties of Aerosol Particles Coated with Palmitic Acid

Author : Joshua Haines
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (915 download)

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Book Synopsis Morphology and Optical Properties of Aerosol Particles Coated with Palmitic Acid by : Joshua Haines

Download or read book Morphology and Optical Properties of Aerosol Particles Coated with Palmitic Acid written by Joshua Haines and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The morphology of aerosol particles influences the reactions that occur during atmospheric aging, as well as altering their contributions to the direct and indirect effects. In order to study the morphology of aerosol particles coated with organic compounds, we have condensed palmitic acid onto ammonium sulfate, quartz, and kaolinite particles with a coating oven. Using transmission electron microscopy, we have determined that the coated particles consist of a core particle with palmitic acid non-uniformly surrounding this core. This particle morphology matches atmospherically relevant particles. However, to our knowledge, particles with this morphology have not been created through the use of a coating oven. The optical properties of the coated particles are characterized through cavity ring-down spectroscopy and compared to Mie scattering calculations. For thick coatings, Mie scattering theory is effective at predicting the extinction cross section of the observed particles. We discuss the atmospheric relevance of the observed particles and their impact on climate-aerosol interactions.

Morphology Dependent Optical Properties of Mixed Organic/Inorganic Aerosol Particles

Author : Kristin Di Monte
Publisher :
ISBN 13 :
Total Pages : 0 pages
Book Rating : 4.:/5 (133 download)

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Book Synopsis Morphology Dependent Optical Properties of Mixed Organic/Inorganic Aerosol Particles by : Kristin Di Monte

Download or read book Morphology Dependent Optical Properties of Mixed Organic/Inorganic Aerosol Particles written by Kristin Di Monte and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Light extinction by atmospheric aerosol particles and their interactions with water are heavily dependent on their chemical composition, morphology, and mixing state. Both properties are crucial for determining the impact aerosol particles have on our climate. Since light extinction directly impacts visibility as well as climate, measurements of the extinction at varying relative humidities (RH) are needed in order to improve climate models. In this work we have measured the relative humidity dependence of aerosol light extinction and water uptake at 643 nm for particles of varying ammonium sulfate/organic compositions. Internal as well as external mixtures of levoglucosan, sucrose, and adipic acid with ammonium sulfate are investigated using cavity ring-down spectroscopy (CRDS). Optical growth factor (fRH) and hygroscopicity parameters ([kappa]) are reported for each aerosol system.

Optical Effects Associated with Small Particles

Author : Peter W. Barber
Publisher : World Scientific
ISBN 13 : 9789971504625
Total Pages : 362 pages
Book Rating : 4.5/5 (46 download)

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Book Synopsis Optical Effects Associated with Small Particles by : Peter W. Barber

Download or read book Optical Effects Associated with Small Particles written by Peter W. Barber and published by World Scientific. This book was released on 1988 with total page 362 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume is a collection of review articles by scientists who have pioneered many of the recent advances in studies of the optical effects of small particles. The book begins with a review of the multitude of sharp dielectric resonances which exist in all optical spectra as a result of particle size and shape. Latest advances in absorption and fluorescence spectroscopy of a single particle and/or an ensemble of particles are also discussed, as well as advances in the energy transfer mechanisms for molecules embedded in the particle. The effects of laser-induced heating on a single particle are reviewed in terms of the hydrodynamics and thermodynamics of the liquid droplet and its ambient gas surrounding. The limits of applying bulk optical constants to small particles which lie between the bulk substance and the quantum-sized substance are also presented.

Measurements of the Chemical, Physical, and Optical Properties of Single Aerosol Particles

Author : Ryan Christopher Moffet
Publisher :
ISBN 13 :
Total Pages : 340 pages
Book Rating : 4.:/5 (758 download)

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Book Synopsis Measurements of the Chemical, Physical, and Optical Properties of Single Aerosol Particles by : Ryan Christopher Moffet

Download or read book Measurements of the Chemical, Physical, and Optical Properties of Single Aerosol Particles written by Ryan Christopher Moffet and published by . This book was released on 2007 with total page 340 pages. Available in PDF, EPUB and Kindle. Book excerpt: Knowledge of aerosol physical, chemical, optical properties is essential for judging the effect that particulates have on human health, climate and visibility. The aerosol time-of-flight mass spectrometer (ATOFMS) is capable of measuring, in real-time, the size and chemical composition of atmospheric aerosols. This was exemplified by the recent deployments of the ATOFMS to Mexico City and Riverside. The ATOFMS provided rapid information about the major particle types present in the atmosphere. Industrial sources of particles, such as fine mode particles containing lead, zinc and chloride were detected in Mexico City. The rapid time response of the ATOFMS was also exploited to characterize a coarse particle concentrator used in human health effects studies. The ATOFMS showed the ability to detect changes in particle composition with a time resolution of 15 min during short 2 hour human exposure studies.

Atmospheric Aerosols: Their Optical Properties and Effects

Author :
Publisher :
ISBN 13 :
Total Pages : 348 pages
Book Rating : 4.:/5 (317 download)

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Book Synopsis Atmospheric Aerosols: Their Optical Properties and Effects by :

Download or read book Atmospheric Aerosols: Their Optical Properties and Effects written by and published by . This book was released on 1976 with total page 348 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Size Dependent Morphology of Organic Aerosol

Author : Muhammad Altaf
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (992 download)

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Book Synopsis Size Dependent Morphology of Organic Aerosol by : Muhammad Altaf

Download or read book Size Dependent Morphology of Organic Aerosol written by Muhammad Altaf and published by . This book was released on 2017 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The Earths atmosphere is composed of a wide variety of gas phase species and particulate matter that have a large impact on our climate. Though our understanding of the climate system has improved significantly over the past few decades, the impact of aerosol particles remains uncertain. Aerosol particles can affect climate through the absorption and scattering of radiation (aerosol direct effect) and by serving as cloud condensation nuclei (aerosol indirect effect). It is known that aerosol particles cause a net cooling effect on the planet, but the magnitude of cooling is unclear and remains under investigation. A large part of this uncertainty is due to an incomplete understanding of the complex physical and chemical properties of aerosol particles such as composition, morphology, and phase state.In this dissertation, we focus on investigating the role of particle size and composition in determining morphology. We have discovered that for some organic aerosol systems, particle morphology depends on size, where small particles are homogeneous and large particles are phase separated. To explore the origins of this size dependent behavior, we have worked with a model organic aerosol system, poly(ethylene glycol)-400 mixed with ammonium sulfate. We have used cryogenic-transmission electron microscopy to probe the effect of phase separation mechanism on particle morphology by varying the organic aerosol composition. Our results suggest that a size dependent morphology occurs due to an activated process, where the presence or absence of an activation barrier to phase separation controls the resulting morphology.We have also explored the kinetics and thermodynamics of the phase separation process that results in a size dependent morphology by varying the experimental drying rates. Drying rates that span over four orders of magnitude were investigated. We have observed that at the fastest drying rates, the size of the transition region where both phase separated and homogeneous morphologies exist is on the order of ~100 nm. At the slowest drying rates, the transition region shifts to smaller diameters and the width narrows to ~3 nm. Our results suggest that a size dependent morphology persists to the slowest drying rates. Thus, we conclude that an underlying thermodynamic effect results in this size dependent behavior, rather than solely a kinetic phenomenon.To determine the atmospheric implications of a size dependent morphology, we have used a cloud condensation nuclei counter to probe the effect of a homogeneous vs. a phase separated morphology on cloud condensation nuclei (CCN) activity. We have found that the activation diameters differ for particles which have the same composition, but varying morphology. Since aerosol optical properties are a sensitive measure of particle structure, we have studied the morphology-resolved optical properties of organic aerosol using cavity ring-down spectroscopy. Our spectroscopy data indicate that the optical properties of core-shell and partially engulfed particles are approximately equal, but different than the prediction for homogeneous particles. By accurately parametrizing aerosol particle morphology, optical properties, and CCN activity we will be able to better predict heterogeneous chemistry in the atmosphere, in addition to the aerosol direct and aerosol indirect effects which play a critical role in constraining climate forcing.

Variation in Morphology, Hygroscopicity, and Optical Properties of Soot Particles Coated by Dicarboxylic Acids

Author : Huaxin Xue
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (66 download)

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Book Synopsis Variation in Morphology, Hygroscopicity, and Optical Properties of Soot Particles Coated by Dicarboxylic Acids by : Huaxin Xue

Download or read book Variation in Morphology, Hygroscopicity, and Optical Properties of Soot Particles Coated by Dicarboxylic Acids written by Huaxin Xue and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Soot aerosols are well known to be atmospheric constituents, but the hydrophobic nature of fresh soot likely prohibits them from encouraging cloud development. Soot aged through contact with oxygenated organic compounds may become hydrophilic enough to promote water uptake. In this study, the tandem differential mobility analyzer (TDMA) and differential mobility analyzer-aerosol particle mass analyzer (DMA-APM) were employed to measure the changes in morphology and hygroscopicity of soot aerosol particles upon coating with succinic and glutaric acids. The effective densities, fractal dimensions and dynamic shape factors of fresh and coated soot aerosol particles have been determined. Significant size-dependent increases of soot particle mobility diameter, mass, and effective density ([rho]eff) were observed upon coating of aggregates with succinic acid. These properties were restored back to their initial states once the acid was removed by heating, suggesting no restructuring of the soot core had occurred. Coating of soot with glutaric acid, on the other hand, leads to a strong size shrinking with a diameter growth factor ~0.60, even after the acid has been removed by heating suggesting the strong restructuring of the soot agglomerate. The additional 90% RH cycle can evidently enhance the restructuring process. The extinction and scattering properties at 532 nm of soot particles internally mixed with dicarboxylic acids were investigated experimentally using a cavity ring-down spectrometer and an integrating nephelometer, respectively, and the absorption is derived as the difference between extinction and scattering. It was found that the organic coatings significantly affect the optical and microphysical properties of the soot aggregates. The size-dependent amplification factors of light scattering were as much as 3.8 and 1.7 with glutaric and succinic acids coatings, respectively. Additional measurements with soot particles that are first coated with glutaric acid and then heated to remove the coating show that both scattering and absorption are enhanced by irreversible restructuring of soot aggregates to more compact globules. These results reveal the microphysical state of soot aerosol with incomplete restructuring in the atmosphere, and advance the treatment of atmospheric aged soot aerosol in the Mie theory shell-and-core model.

Models for the Aerosols of the Lower Atmosphere and the Effects of Humidity Variations on Their Optical Properties

Author : Eric P. Shettle
Publisher :
ISBN 13 :
Total Pages : 100 pages
Book Rating : 4.3/5 (91 download)

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Book Synopsis Models for the Aerosols of the Lower Atmosphere and the Effects of Humidity Variations on Their Optical Properties by : Eric P. Shettle

Download or read book Models for the Aerosols of the Lower Atmosphere and the Effects of Humidity Variations on Their Optical Properties written by Eric P. Shettle and published by . This book was released on 1979 with total page 100 pages. Available in PDF, EPUB and Kindle. Book excerpt: Aerosol models have been developed for the lower atmosphere. These models are representative of conditions found in rural, urban, and maritime air masses. The changes in the aerosol properties with variations in the relative humidity are discussed. To describe the aerosol optical properties in the extreme of 100 percent relative humidity, several fog models are presented. For each model the coefficients for extinction, scattering, and absorption, the angular scattering distribution, and other optical parameters have been computed for wavelengths between 0.2 and 40 microns. These aerosol models are presented together with a review of their experimental basis. The optical properties of these models are discussed and some comparisons of the model with experimental measurements are presented.

Aerosol Optics

Author : Alexander A. Kokhanovsky
Publisher : Springer Science & Business Media
ISBN 13 : 3540499091
Total Pages : 154 pages
Book Rating : 4.5/5 (44 download)

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Book Synopsis Aerosol Optics by : Alexander A. Kokhanovsky

Download or read book Aerosol Optics written by Alexander A. Kokhanovsky and published by Springer Science & Business Media. This book was released on 2008-03-18 with total page 154 pages. Available in PDF, EPUB and Kindle. Book excerpt: This new text offers experienced students a comprehensive review of available techniques for the remote sensing of aerosols. These small particles influence both atmospheric visibility and the thermodynamics of the atmosphere. They are also of great importance in any consideration of climate change problems. Aerosols may also be responsible for the loss of harvests, human health problems and ecological disasters. Thus, this detailed study of aerosol properties on a global scale could not be more timely.

The Effects of Aerosol Acidity on the Morphology and Ice Nucleation of Aerosol Particles

Author : Delanie Losey
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (12 download)

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Book Synopsis The Effects of Aerosol Acidity on the Morphology and Ice Nucleation of Aerosol Particles by : Delanie Losey

Download or read book The Effects of Aerosol Acidity on the Morphology and Ice Nucleation of Aerosol Particles written by Delanie Losey and published by . This book was released on 2017 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Aerosol particle morphology can influence the water uptake, heterogeneous chemistry, and optical properties of the particle. This morphology is known to be dependent on the composition of the particle as well as relative humidity. Recent studies have pointed out the importance of pH in aerosol particles. The pH of systems being investigated during phase transition studies have not investigated the role of pH, which could lead to the deprotonation of the organic component and would affect phase transitions. To investigate the influence of high pH and therefore deprotonation on the phase transitions of 3-methylglutaric acid:ammonium sulfate, sodium hydroxide was used to make solutions with pHs below the pKa1, between the pKa1 and pKa2, and above pKa2 of 3-methylglutaric acid. Using optical microscopy and an environmental chamber, the separation relative humidity (SRH), mixing relative humidity (MRH), efflorescence relative humidity (ERH) and deliquescence relative humidity (DRH) were recorded for each system. As the pH of the system was increased, the SRH decreased. This was attributed to the increased solubility of the organic component in water when it was deprotonated. The ERH also changed to higher values with added sodium hydroxide. The MRH and DRH values, however, remained constant over all pH. A previously unobserved hysteresis was found between SRH and MRH and the atmospheric implications are discussed. The influence of low pH was also explored in a similar manner, but through addition of concentrated sulfuric acid. Stoichiometric amounts of sulfuric acid was added to six different organic:ammonium sulfate systems to change the salt identity to letovicite, (NH4)3H(SO4)2, and ammonium bisulfate, NH4HSO4. An experiment at low pH was also conducted for each system. In every case, the addition of sulfuric acid led to an overall decrease in SRH, as expected with changing salt identity. Furthermore, at the lowest pH studied the SRH of four of the six systems were so low that phase separation would not occur in atmospherically relevant conditions. Also, phase separation could occur with no inorganic salt present at all. The ERH and DRH for each system also were affected. These results could affect mass transfer and water uptake for systems at low pH, and can be further explored by investigating the role of pH in particle viscosity and submicron aerosol morphology. Fly ash can undergo aging in the atmosphere through interactions with sulfuric acid and water. These reactions can lead to physical and chemical changes caused by reaction products or chemical leaching. These changes could influence the amount of soluble material on the particle as well as the ability of the particle to nucleate ice. Both of these affect the fly ash particles ability to serve as a cloud nucleus. The extent of these changes is expected to be linked to the chemical composition of the fly ash so three fly ash types were investigated. The effect of water- and acid-treatment were assessed using X-ray diffraction, attenuated total reflectance infrared spectroscopy, transmission electron microscopy with selected area electron diffraction and energy dispersive spectroscopy, inductively coupled plasma-atomic emission spectroscopy, Brunauer-Emmett-Teller surface area analysis, and immersion freezing. The results show the presence of soluble material on fly ash and indicate that sulfuric-acid treatment has major physical and chemical effects on fly ash. These effects are dependent on composition of the fly ash. Acid-treatment results in gypsum being created and a variety of metals to be leached, and these changes did affect the immersion ice nucleation activity of the samples. Further studies of these effects on deposition mode freezing are expected for the future.

Aerosol Technology

Author : William C. Hinds
Publisher : John Wiley & Sons
ISBN 13 : 1119494044
Total Pages : 452 pages
Book Rating : 4.1/5 (194 download)

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Book Synopsis Aerosol Technology by : William C. Hinds

Download or read book Aerosol Technology written by William C. Hinds and published by John Wiley & Sons. This book was released on 2022-05-24 with total page 452 pages. Available in PDF, EPUB and Kindle. Book excerpt: AEROSOL TECHNOLOGY An in-depth and accessible treatment of aerosol theory and its applications The Third Edition of Aerosol Technology: Properties, Behavior, and Measurement of Airborne Particles delivers a thorough and authoritative exploration of modern aerosol theory and its applications. The book offers readers a working knowledge of the topic that reflects the numerous advances that have been made across a broad spectrum of aerosol-related application areas. New updates to the popular text include treatments of nanoparticles, the health effects of atmospheric aerosols, remote sensing, bioaerosols, and low-cost sensors. Additionally, readers will benefit from insightful new discussions of modern instruments. The authors maintain a strong focus on the fundamentals of the discipline, while providing a robust overview of real-world applications of aerosol theory. New exercise problems and examples populate the book, which also includes: Thorough introductions to aerosol technology, key definitions, particle size, shape, density, and concentration, as well as the properties of gases Comprehensive explorations of uniform particle motion, particle size statistics, and straight-line acceleration and curvilinear particle motion Practical discussions of particle adhesion, Brownian motion and diffusion, thermal and radiometric forces, and filtration In-depth examinations of sampling and measurement of concentration, respiratory deposition, coagulation, condensation, evaporation, and atmospheric aerosols Perfect for senior undergraduate and junior graduate students of science and technology, Aerosol Technology: Properties, Behavior, and Measurement of Airborne Particles will also earn a place in the libraries of professionals working in industrial hygiene, air pollution control, climate science, radiation protection, and environmental science.

Aerosol Hygroscopic Properties

Author : Danielle El Hajj
Publisher :
ISBN 13 :
Total Pages : 0 pages
Book Rating : 4.:/5 (113 download)

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Book Synopsis Aerosol Hygroscopic Properties by : Danielle El Hajj

Download or read book Aerosol Hygroscopic Properties written by Danielle El Hajj and published by . This book was released on 2019 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Aerosols play vital roles in energy balance of the Earth and also have a significant impact on human health. The last assessment report by the Intergovernmental Panel on Climate Change (IPCC), states that the uncertainty in the total radiative forcing is mainly dominated by the high uncertainty in the aerosol radiative forcing. This is mainly caused by the poorly understood and quantified aerosol effects. Indeed, high relative humidity (RH), promotes water uptake by atmospheric aerosol particles, which modifies their size, morphology and chemical composition and therefore their optical properties. In-situ measurements of aerosols properties (scattering and absorption coefficients, size distribution) are usually performed at dry conditions (RH

Fundamentals and Applications in Aerosol Spectroscopy

Author : Ruth Signorell
Publisher : CRC Press
ISBN 13 : 142008562X
Total Pages : 513 pages
Book Rating : 4.4/5 (2 download)

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Book Synopsis Fundamentals and Applications in Aerosol Spectroscopy by : Ruth Signorell

Download or read book Fundamentals and Applications in Aerosol Spectroscopy written by Ruth Signorell and published by CRC Press. This book was released on 2010-12-20 with total page 513 pages. Available in PDF, EPUB and Kindle. Book excerpt: Helping you better understand the processes, instruments, and methods of aerosol spectroscopy, Fundamentals and Applications in Aerosol Spectroscopy provides an overview of the state of the art in this rapidly developing field. It covers fundamental aspects of aerosol spectroscopy, applications to atmospherically and astronomically relevant problem

MORPHOLOGY AND MIXING STATE OF SOOT AND TAR BALLS

Author :
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (114 download)

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Book Synopsis MORPHOLOGY AND MIXING STATE OF SOOT AND TAR BALLS by :

Download or read book MORPHOLOGY AND MIXING STATE OF SOOT AND TAR BALLS written by and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract : Soot particles form during incomplete combustion of carbonaceous materials. These particles strongly absorb light and directly affect Earth's climate by warming our atmosphere. When freshly emitted, soot particles have a fractal-like morphology consisting of aggregates of carbon spherules. During atmospheric processing, soot aggregates interact with other materials present in our atmosphere (i.e., other aerosol or condensable vapors) and these interactions can result in the formation of coated, mixed or compacted soot particles with different morphologies. Any process that alters the morphology (shape, size and internal structure) and mixing state of soot also affects its optical properties, which in turn affect the soot radiative forcing in the atmosphere. The complex morphology and internal mixing state of soot makes it difficult to estimate the soot's radiative properties. A detailed investigation of soot at the single particle level using electron microscopy, thus, becomes essential to provide accurate information for climate models, which generally assumes simple spherical morphologies. Tar balls are another type of carbonaceous aerosol, in the brown carbon family, commonly formed during smoldering combustion of biomass materials. Like soot, tar balls can also form aggregates. Tar balls aggregates have different optical properties from those of individual tar balls. During my doctorate studies, I made extensive use of electron microscopy and image analysis tools to investigate the morphology and mixing state of soot and tar balls collected during different laboratory and field studies. In one of my research projects, I explored the morphology of cloud processed soot. For this, I investigated the morphology of soot particles collected from the Po Valley in Italy where fog often forms, especially in winter. Our investigation showed that soot particles became compacted after fog processing. The compaction of soot was further corroborated by a laboratory study, in which cloud processing was carried out within the Michigan Technological University cloud chamber. In another research project, I studied the effects of thermodenuding on the morphology of soot. I investigated the morphology of five sets of soot samples of different sizes before xiii and after themodenuding. Our investigation showed no significant change in the morphology of soot by thermodenuding, a result that is important for those who attempt to measure the optical properties of internally mixed coated particles. In a third study, I used T-Matrix and Lorenz-Mie models to calculate the optical properties and then estimate the radiative forcing of tar ball aggregates and individual tar balls. In fact, in a recent publication, we reported a significant fraction of tar ball aggregates from different locations on Earth. My numerical calculations showed that the optical properties of tar ball aggregates are different from those of individual tar balls and are not always well approximated by Lorentz-Mie calculations. These findings highlight the necessity to account for the aggregation of tar balls in global models. My doctorate research provides detailed information on the morphology and mixing state of soot and tar ball aggregates. This information can be used to improve global climate models and reduce uncertainties in the radiative forcing of these aerosol particles.

Optical Properties of Mineral Dust Aerosol Including Analysis of Particle Size, Composition, and Shape Effects, and the Impact of Physical and Chemical Processing

Download Optical Properties of Mineral Dust Aerosol Including Analysis of Particle Size, Composition, and Shape Effects, and the Impact of Physical and Chemical Processing PDF Online Free

Author : Jennifer Mary Alexander
Publisher :
ISBN 13 :
Total Pages : 195 pages
Book Rating : 4.:/5 (925 download)

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Book Synopsis Optical Properties of Mineral Dust Aerosol Including Analysis of Particle Size, Composition, and Shape Effects, and the Impact of Physical and Chemical Processing by : Jennifer Mary Alexander

Download or read book Optical Properties of Mineral Dust Aerosol Including Analysis of Particle Size, Composition, and Shape Effects, and the Impact of Physical and Chemical Processing written by Jennifer Mary Alexander and published by . This book was released on 2015 with total page 195 pages. Available in PDF, EPUB and Kindle. Book excerpt: Atmospheric mineral dust has a large impact on the earth's radiation balance and climate. The radiative effects of mineral dust depend on factors including, particle size, shape, and composition which can all be extremely complex. Mineral dust particles are typically irregular in shape and can include sharp edges, voids, and fine scale surface roughness. Particle shape can also depend on the type of mineral and can vary as a function of particle size. In addition, atmospheric mineral dust is a complex mixture of different minerals as well as other, possibly organic, components that have been mixed in while these particles are suspended in the atmosphere. Aerosol optical properties are investigated in this work, including studies of the effect of particle size, shape, and composition on the infrared (IR) extinction and visible scattering properties in order to achieve more accurate modeling methods. Studies of particle shape effects on dust optical properties for single component mineral samples of silicate clay and diatomaceous earth are carried out here first. Experimental measurements are modeled using T-matrix theory in a uniform spheroid approximation. Previous efforts to simulate the measured optical properties of silicate clay, using models that assumed particle shape was independent of particle size, have achieved only limited success. However, a model which accounts for a correlation between particle size and shape for the silicate clays offers a large improvement over earlier modeling approaches. Diatomaceous earth is also studied as an example of a single component mineral dust aerosol with extreme particle shapes. A particle shape distribution, determined by fitting the experimental IR extinction data, used as a basis for modeling the visible light scattering properties.

Light Scattering From Micrometric Mineral Dust and Aggregate Particles

Author : Llorenç Cremonesi
Publisher : Springer Nature
ISBN 13 : 3030567877
Total Pages : 148 pages
Book Rating : 4.0/5 (35 download)

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Book Synopsis Light Scattering From Micrometric Mineral Dust and Aggregate Particles by : Llorenç Cremonesi

Download or read book Light Scattering From Micrometric Mineral Dust and Aggregate Particles written by Llorenç Cremonesi and published by Springer Nature. This book was released on 2020-09-24 with total page 148 pages. Available in PDF, EPUB and Kindle. Book excerpt: Light scattering from particles in the nanometric and micrometric size range is relevant in several research fields, such as aerosol science and nanotechnology. In many applications, the description of the optical properties of non-spherical, inhomogeneous particles is still inadequate or requires demanding numerical calculations. Lorenz–Mie scattering and effective medium approximations represent currently the main theoretical tools to model such particles, but their effectiveness has been recently called into question. This work examines how the morphology of a particle affects its scattering parameters from an experimental standpoint, supporting findings with extensive simulations. The dust content of Antarctic, Greenlandic, and Alpine ice cores is analysed with a particle-by-particle approach. Moreover, a study on colloidal aggregates shows that correlations among the fields radiated by primary particles are responsible for the poor agreement of effective medium approximations with experimental results. On the theoretical side, an interpretation in terms of the structure factor is given, which satisfactorily describes the data. The insights of this thesis are relevant for quantifying the contribution of mineral dust to the radiative energy balance of the Earth.