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Author: Prakash Gautam
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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Book Description
We investigated light scattering due to irregularly shaped aerosol particles with diverse shapes, sizes, and complex refractive indices. We have designed and developed a light scattering setup based on a novel optical scheme that can detect light from 0.32° and 177.6°, from an extreme forward to the backscattering regime, involving 46 angles. Our setup was able to measure all six independent scattering matrix elements; however, we focused on measuring the scattering intensity and the linear depolarization ratio for different dust particles. Given the extremely small and large angles, the data obtained for our setup are plotted on both: versus scattering angle, [theta] linearly, and scattering wave vector, q or qR with R the radius of a particle, on a log-log scale, called [theta] and Q-space respectively. The Q- space analysis best represents the data at the extreme forward scattering regime; however, it compresses the data at the large scattering angles, [theta] , where useful data also reside. At large scattering angles, the scattered intensity is best viewed by [theta]-space analysis. We scattered the light from different aerosol particles viz; silicon dioxide (SiO2), aluminum abrasive (Al2O3), a highly refractive molybdenum disulfide (MoS2), a highly absorptive hematite particle ([alpha]--Fe2O3), arizona road dust and Soot particles. The measured scattered intensity was interpreted by applying both analysis methods. Light scattering for all particle types was compared to theoretical Mie scattering calculations using size distributions determined by an Aerodynamic Particle Sizer (APS 3321), an aerosol measuring instrument. The compared results between the experimentally measured data and Mie calculations showed a close agreement at the forward scattering regime and poorly at the side and backscattering regimes. Effects of the intensity-weighted size distribution were discussed. We applied Guinier analysis on light scattering measured data to compare light scattering inferred size to the intensity-weighted mean sizes for all shape particles. The light scattering sizes were consistent with the intensity-weighted mean sizes of reasonable accuracy for any shape and refractive index. This result has demonstrated the importance of intensity weighting of the size distribution in light scattering. We measured and studied the linear depolarization ratio for different dust particles. They all displayed a common pattern. The measured values were negligibly small at the forward scattering regime. They increased with increasing the scattering angle and reached a maximum at the side scattering regime that generally droped off at the backscattering regime. The effects of particle asphericity, size, and refractive index on the linear depolarization ratio were investigated. We further investigate the light scattering from fractal soot and non-fractal hematite aggregates. The results showed an enhancement in the backscattering despite a large imaginary refractive index. We found that enhancement backscattering for the non-fractal aggregate is due to internal multiple scattering between the grains within the aggregate. In contrast, enhancement backscattering is yet to be understood for fractal soot aggregates. Furthermore, the results presented in this work showed the sensitive of light backscattering with the change in particles' shapes, sizes, and refractive indices and warn the experimentalist to use the backscattering measured data with great caution.
Author: Prakash Gautam
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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Book Description
We investigated light scattering due to irregularly shaped aerosol particles with diverse shapes, sizes, and complex refractive indices. We have designed and developed a light scattering setup based on a novel optical scheme that can detect light from 0.32° and 177.6°, from an extreme forward to the backscattering regime, involving 46 angles. Our setup was able to measure all six independent scattering matrix elements; however, we focused on measuring the scattering intensity and the linear depolarization ratio for different dust particles. Given the extremely small and large angles, the data obtained for our setup are plotted on both: versus scattering angle, [theta] linearly, and scattering wave vector, q or qR with R the radius of a particle, on a log-log scale, called [theta] and Q-space respectively. The Q- space analysis best represents the data at the extreme forward scattering regime; however, it compresses the data at the large scattering angles, [theta] , where useful data also reside. At large scattering angles, the scattered intensity is best viewed by [theta]-space analysis. We scattered the light from different aerosol particles viz; silicon dioxide (SiO2), aluminum abrasive (Al2O3), a highly refractive molybdenum disulfide (MoS2), a highly absorptive hematite particle ([alpha]--Fe2O3), arizona road dust and Soot particles. The measured scattered intensity was interpreted by applying both analysis methods. Light scattering for all particle types was compared to theoretical Mie scattering calculations using size distributions determined by an Aerodynamic Particle Sizer (APS 3321), an aerosol measuring instrument. The compared results between the experimentally measured data and Mie calculations showed a close agreement at the forward scattering regime and poorly at the side and backscattering regimes. Effects of the intensity-weighted size distribution were discussed. We applied Guinier analysis on light scattering measured data to compare light scattering inferred size to the intensity-weighted mean sizes for all shape particles. The light scattering sizes were consistent with the intensity-weighted mean sizes of reasonable accuracy for any shape and refractive index. This result has demonstrated the importance of intensity weighting of the size distribution in light scattering. We measured and studied the linear depolarization ratio for different dust particles. They all displayed a common pattern. The measured values were negligibly small at the forward scattering regime. They increased with increasing the scattering angle and reached a maximum at the side scattering regime that generally droped off at the backscattering regime. The effects of particle asphericity, size, and refractive index on the linear depolarization ratio were investigated. We further investigate the light scattering from fractal soot and non-fractal hematite aggregates. The results showed an enhancement in the backscattering despite a large imaginary refractive index. We found that enhancement backscattering for the non-fractal aggregate is due to internal multiple scattering between the grains within the aggregate. In contrast, enhancement backscattering is yet to be understood for fractal soot aggregates. Furthermore, the results presented in this work showed the sensitive of light backscattering with the change in particles' shapes, sizes, and refractive indices and warn the experimentalist to use the backscattering measured data with great caution.
Author: Schuerman
Publisher: Springer Science & Business Media
ISBN: 1468437046
Category : Technology & Engineering
Languages : en
Pages : 335
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Book Description
This volume contains most of the invited papers presented at the International Workshop on Light Scattering by Irregularly Shaped Particles held on June 5-7, 1979. at the State University of New York at Albany (SUNYA). Over seventy participants representing many dis ciplines convened to define some of the ever-increasing number of resonant light-scattering problems associated with particle shape and to relate their most recent investigations in this field. It is obvious from the two introductory papers that an investi gator's primary discipline determines his/her approach to the light scattering problem. The meteorologist, Diran Deirmendjian, advocates an empirical methodology: to model the scattering by atmospheric aerosols, using equivalent spheres as standards, in the most effi cient and simplest manner that is consistent with remote sensing, in situ, and laboratory· data. Because of the almost infinite variety of particle shapes, he questions not only the possibility but even the usefulness of the exact solution of scattering by a totally arbitrary particle. The astrophysicist, J. Mayo Greenberg, is primarily concerned with the information content carried by the scattered light because this radiation is the sole clue to under standing the nature of interstellar dust. What measurements (polar ization, color dependence, etc ••• ) should be made to best determine a given particle characteristic (size, surface roughness, refractive index, etc ••• )? Thus, he considers the physics of the scattering process to be of paramount interest.
Author: Miroslaw Jonasz
Publisher: Elsevier
ISBN: 0080548679
Category : Science
Languages : en
Pages : 715
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Book Description
Light scattering-based methods are used to characterize small particles suspended in water in a wide range of disciplines ranging from oceanography, through medicine, to industry. The scope and accuracy of these methods steadily increases with the progress in light scattering research. This book focuses on the theoretical and experimental foundations of the study and modeling of light scattering by particles in water and critically evaluates the key constraints of light scattering models. It begins with a brief review of the relevant theoretical fundamentals of the interaction of light with condensed matter, followed by an extended discussion of the basic optical properties of pure water and seawater and the physical principles that explain them. The book continues with a discussion of key optical features of the pure water/seawater and the most common components of natural waters. In order to clarify and put in focus some of the basic physical principles and most important features of the experimental data on light scattering by particles in water, the authors employ simple models. The book concludes with extensive critical reviews of the experimental constraints of light scattering models: results of measurements of light scattering and of the key properties of the particles: size distribution, refractive index (composition), structure, and shape. These reviews guide the reader through literature scattered among more than 210 scientific journals and periodicals which represent a wide range of disciplines. A special emphasis is put on the methods of measuring both light scattering and the relevant properties of the particles, because principles of these methods may affect interpretation and applicability of the results. The book includes extensive guides to literature on light scattering data and instrumentation design, as well as on the data for size distributions, refractive indices, and shapes typical of particles in natural waters. It also features a comprehensive index, numerous cross-references, and a reference list with over 1370 entries. An errata sheet for this work can be found at: http://www.tpdsci.com/Ref/Jonasz_M_2007_LightScatE.php *Extensive reference section provides handy compilations of knowledge on the designs of light scattering meters, sources of experimental data, and more *Worked exercises and examples throughout
Author: Alexander Kokhanovsky
Publisher: Springer Nature
ISBN: 3031102983
Category : Science
Languages : en
Pages : 201
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Book Description
This book is aimed at description of recent progress in studies of multiple and single light scattering in turbid media. Light scattering and radiative transfer research community will greatly benefit from the publication of this book.
Author: Fernando Moreno
Publisher: Springer
ISBN: 3540466142
Category : Technology & Engineering
Languages : en
Pages : 293
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Book Description
The classical phenomenon of light scattering is one of the most studied t- ics in light-matter interaction and, even today, involves some controversial issues. A present focus of interest for many researchers is the possibility of obtaining information about microstructures, for example surface roughness, and the size, shape and optical properties of particles by means of a n- invasive technique such as the illumination of these objects with light. One of their main tasks is to extract the relevant information from a detailed study of the scattered radiation. This includes: measurement of the light intensity in di erent directions, analysis of its polarization, determination of its stat- tics,etc. Contributionstoresolvingthisproblemareimportantnotonlyfrom the point of view of increasing basic knowledge but also in their applications to several elds of industry and technology. Consider, for example, the pos- bility of distinguishing between di erent types of atmospheric contaminants, biological contaminants in our blood, the detection of microdefects in the manufacturing of semiconductors, magnetic discs and optical components, or the development of biological sensors. During the period September 11-13, 1998, we brought together a group of international experts on light scattering at the Summer School of Laredo at the University of Cantabria. In a series of one-hour lectures, they discussed currentaspectsoflightscatteringfrommicrostructureswithspecialemphasis on recent applications. The present book condenses those lectures into ve parts.
Author: Alexander Kokhanovsky
Publisher: Springer Nature
ISBN: 3030876837
Category : Science
Languages : en
Pages : 165
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Book Description
The book aims to the description of recent progress in studies of light absorption and scattering in turbid media. In particular, light scattering/oceanic optics/snow optics research community will greatly benefit from the publication of this book.
Author: Craig F. Bohren
Publisher: John Wiley & Sons
ISBN: 3527618163
Category : Science
Languages : en
Pages : 544
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Book Description
Absorption and Scattering of Light by Small Particles Treating absorption and scattering in equal measure, this self-contained, interdisciplinary study examines and illustrates how small particles absorb and scatter light. The authors emphasize that any discussion of the optical behavior of small particles is inseparable from a full understanding of the optical behavior of the parent material-bulk matter. To divorce one concept from the other is to render any study on scattering theory seriously incomplete. Special features and important topics covered in this book include: * Classical theories of optical properties based on idealized models * Measurements for three representative materials: magnesium oxide, aluminum, and water * An extensive discussion of electromagnetic theory * Numerous exact and approximate solutions to various scattering problems * Examples and applications from physics, astrophysics, atmospheric physics, and biophysics * Some 500 references emphasizing work done since Kerker's 1969 work on scattering theory * Computer programs for calculating scattering by spheres, coated spheres, and infinite cylinders
Author: Toru Yoshizawa
Publisher: CRC Press
ISBN: 1420019511
Category : Science
Languages : en
Pages : 746
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Book Description
The field of optical metrology offers a wealth of both practical and theoretical accomplishments, and can cite any number of academic papers recording such. However, while several books covering specific areas of optical metrology do exist, until the pages herein were researched, written, and compiled, the field lacked for a comprehensive handbook, one providing an overview of optical metrology that covers practical applications as well as fundamentals. Carefully designed to make information accessible to beginners without sacrificing academic rigor, the Handbook of Optical Metrology: Principles and Applications discusses fundamental principles and techniques before exploring practical applications. With contributions from veterans in the field, as well as from up-and-coming researchers, the Handbook offers 30 substantial and well-referenced chapters. In addition to the introductory matter, forward-thinking descriptions are included in every chapter that make this a valuable reference for all those involved with optical metrology.
Author: Llorenç Cremonesi
Publisher: Springer Nature
ISBN: 3030567877
Category : Science
Languages : en
Pages : 148
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Book Description
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.
Author: Ferdinando Borghese
Publisher: Springer Science & Business Media
ISBN: 3540374140
Category : Science
Languages : en
Pages : 358
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Book Description
This book provides the first coherent account of a well-known approach to the problem of light scattering by small anisotropic particles. In this extended second edition the authors have encompassed all the new topics arising from their recent studies of cosmic dust grains. Thus many chapters were deeply revised and new chapters were added. The book addresses a wide spectrum of applications.
