Tai Lieu Chat Luong Fundamentals and Applications in Aerosol Spectroscopy Fundamentals and Applications in Aerosol Spectroscopy Edited by Ruth Signorell ■ Jonathan P. Reid MATLAB® is a trademark of The MathWorks, Inc. and is used with permission. The MathWorks does not warrant the accuracy of the text or exercises in this book.
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Trademark Notice: Product or corporate names may be trademarks or registered trademarks, and are used only for identification and explanation without intent to infringe. Visit the Taylor & Francis Web site at http://www.com and the CRC Press Web site at http://www.com Contents Preface. xv Section I Infrared Spectroscopy Chapter 1 Infrared Spectroscopy of Aerosol Particles.3 Thomas Leisner and Robert Wagner Chapter 2 Vibrational Excitons: A Molecular Model to Analyze Infrared Spectra of Aerosols. 25 George Firanescu, Thomas C.
Wang, and Ruth Signorell Chapter 3 Aerosol Nanocrystals of Water Ice: Structure, Proton Activity, Adsorbate Effects, and H-Bond Chemistry. Paul Devlin Chapter 4 Infrared Extinction and Size Distribution Measurements of Mineral Dust Aerosol. Kleiber, and Vicki H. Grassian Chapter 5 Infrared Spectroscopy of Dust Particles in Aerosols for Astronomical Application.
101 Akemi Tamanai and Harald Mutschke Section II Raman Spectroscopy Chapter 6 Linear and Nonlinear Raman Spectroscopy of Single Aerosol Particles. Kwamena and Jonathan P. Reid Chapter 7 Raman Spectroscopy of Single Particles Levitated by an Electrodynamic Balance for Atmospheric Studies. Lee and Chak K.
Chan v vi Contents Chapter 8 Micro-Raman Spectroscopy for the Analysis of Environmental Particles. 193 Sanja Potgieter-Vermaak, Anna Worobiec, Larysa Darchuk, and Rene Van Grieken Chapter 9 Raman Lidar for the Characterization of Atmospheric Particulate Pollution.209 Detlef Müller Section III VIS/UV Spectroscopy, Fluorescence, and Scattering Chapter 10 UV and Visible Light Scattering and Absorption Measurements on Aerosols in the Laboratory. 243 Zbigniew Ulanowski and Martin Schnaiter Chapter 11 Progress in the Investigation of Aerosols’ Optical Properties Using Cavity Ring-Down Spectroscopy: Theory and Methodology. 269 Ali Abo Riziq and Yinon Rudich Chapter 12 Laser-Induced Fluorescence Spectra and Angular Elastic Scattering Patterns of Single Atmospheric Aerosol Particles.
Chang Chapter 13 Femtosecond Spectroscopy and Detection of Bioaerosols. 321 Luigi Bonacina and Jean-Pierre Wolf Chapter 14 Light Scattering by Fractal Aggregates. Sorensen Section IV UV, X-ray, and Electron Beam Studies Chapter 15 Aerosol Photoemission. Wilson, Hendrik Bluhm, and Musahid Ahmed Chapter 16 Elastic Scattering of Soft X-rays from Free Size-Selected Nanoparticles.
401 Harald Bresch, Bernhard Wassermann, Burkhard Langer, Christina Graf, and Eckart Rühl Contents vii Chapter 17 Scanning Transmission X-ray Microscopy: Applications in Atmospheric Aerosol Research. Tivanski, and Mary K. Gilles Chapter 18 Electron Beam Analysis and Microscopy of Individual Particles. 463 Alexander Laskin Index.
493 Preface This book is intended to provide an introduction to aerosol spectroscopy and an overview of the state-of-the-art of this rapidly developing field. It includes fundamental aspects of aerosol spectro scopy as well as applications to atmospherically and astronomically relevant problems. Basic knowl- edge is the prerequisite for any application. However, in aerosol spectroscopy, as in many other fields, there remain crucial gaps in our understanding of the fundamental processes.
Filling this gap can only be a first step, with the challenge then remaining to develop instruments and methods based on those fundamental insights, instruments that can easily be used to study aerosols in plan- etary atmospheres as well as in space. With this in mind, this book also touches upon some of the aspects that need further research and development. As a guideline, the chapters in this book are arranged in the order of decreasing wavelength of light/electrons, starting with infrared spectros- copy and concluding with x-ray and electron beam studies. Infrared spectroscopy is one of the most important aerosol characterization methods in labora- tory studies, for field measurements, for remote sensing, and in space missions.
It provides a wealth of information about aerosol particles ranging from properties such as particle size and shape to information on their composition and chemical reactivity. The analysis of spectral information, however, is still a challenge. In Chapter 1, Leisner and Wagner provide a detailed description of the most widely used method to analyze infrared extinction spectra, namely classical scattering theory in combination with continuum models of the optical properties of aerosol particles. The authors explain how information such as number concentration, size distribution, chemical composition, and shape can be retrieved from infrared spectra, and outline where pitfalls could occur.
Theoretical considerations are illustrated with experiments performed in the large cloud chamber, aerosol inter- action and dynamics in the atmosphere (AIDA). Classical scattering theory and continuum models for optical properties are not always suitable for a detailed analysis of particle properties. Available optical data are often not accurate enough, and for small particles, where the molecular structure becomes important, these methods fail alto- gether. In Chapter 2, Firanescu, Preston, Wang, and Signorell discuss a molecular model that allows a detailed analysis of particle properties on the basis of the band shapes observed in infrared extinc- tion spectra.
In particular, this approach explains why and when infrared spectra of molecular aerosols are determined by particle properties such as shape, size, or architecture. After a descrip- tion of the approach, the authors illustrate its application by means of a variety of examples. Water and ice are the most important components of aerosols in our Earth’s atmosphere. They play a crucial role in many atmospheric processes.
Water ice is also ubiquitous beyond our planet and solar system. In Chapter 3, Devlin uses infrared spectroscopy to characterize this important type of particle and shows how the structural properties of pure and mixed ice nanocrystals can be unraveled by this technique. Special consideration is given to the nature of the surface of these particles, the role it plays, and how it is influenced by adsorbates. The formation and transformation of numerous naturally occurring hydrates are discussed.
These studies reveal the exceptional prop- erties of water ice surfaces. Chapters 4 and 5 are devoted to the infrared spectroscopy of dust particles. The infrared radia- tive effects of mineral dust aerosols in the Earth’s atmosphere are investigated by Hudson, Young, Kleiber, and Grassian in Chapter 4. Remote sensing studies using infrared data from satellites pro- vide the source of information to determine the radiative effects of these particles.
Such data are commonly analyzed using Mie theory, which treats all particles as spheres. The authors discuss the errors associated with this assumption and demonstrate that the proper treatment of particle ix x Preface shape is crucial in retrieving reliable information about the radiative effect of mineral dust particles from remote sensing. The properties of dust grains occurring in astrophysical environments are the subject of Chapter 5 by Tamanai and Mutschke. Dust grains of different composition with sizes in the micrometer range are widely distributed throughout space.
Ground-based as well as satellite- based telescopes are used for infrared studies of these dust particles. Tamanai and Mutschke dis- cuss infrared laboratory studies of astrophysically relevant dust grains and their application to the interpretation of astronomical spectra. While the wide variety of dust properties makes spectral analysis a difficult task, the authors demonstrate that important information can be obtained from such measurements about the conditions under which dust grains exist and evolve in astronomical environments. Raman spectroscopy has proved to be a versatile tool for examining aerosol particles in con- trolled laboratory measurements, allowing the unambiguous identification of chemical species, the determination of particle composition, and even the determination of particle size and temperature.
Although Raman scattering is inherently a weak process, measurements have been routinely per- formed on droplet trains using pulsed laser and continuous-wave laser techniques, on aerosol parti- cles isolated in optical or electrodynamic traps, and on particles deposited on substrates. Section II begins with a general introduction to the fundamentals of both linear and nonlinear Raman scatter- ing from aerosol particles. In particular, Kwamena and Reid highlight the considerable accuracy (<1 nm) that can be achieved in the determination of droplet size from the unique fingerprint of enhanced Raman scattering that occurs at discrete wavelengths commensurate with whispering gal- lery modes, also referred to as morphology-dependent resonances. Before reviewing some recent applications of Raman spectroscopy for characterizing aerosol, they introduce some of the key experimental considerations that must be remembered when designing a Raman instrument for aerosol studies.
Lee and Chan describe the coupling of Raman spectroscopy with an electrody- namic balance in Chapter 7, outlining how information gained from Raman measurements can complement that from other methods, including light scattering for probing particle size and mor- phology, or tracking evolving particle mass. In particular, they review recent studies of hygroscopic- ity and heterogeneous chemistry. They demonstrate that resolving Raman line shapes can provide important insights into intermolecular interactions between solvent and solute molecules within the condensed aerosol phase, particularly important for understanding the properties of metastable supersaturated states accessed at high solute concentrations. Raman analysis can provide an important tool for characterizing particulate matter of atmo- spheric origin as well as for probing particles in controlled laboratory measurements.
Potgieter- Vermaak, Worobiec, Darchuk, and Van Grieken review the application of micro-Raman spectroscopy for the analysis of environmental particles in Chapter 8. They begin by reviewing the methods avail- able for ambient sampling and the importance of choosing suitable substrates, before discussing the advantages and challenges of utilizing the technique on a stand-alone basis. The practicalities of coupling micro-Raman measurements with other techniques, such as scanning electron microscopy coupled with energy-dispersive x-ray spectrometric detection, are also described and assessed. Key uncertainties remain in the direct and indirect impact of aerosols on climate, and coordi- nated monitoring of the temporal variability of global aerosol distribution is a basic requirement of climate research.
In Chapter 9, Müller describes the application of Raman LIDAR (light detec- tion and ranging) in the characterization of atmospheric pollution. After a description of the basic principles of Raman LIDAR, methods for deriving the optical and microphysical properties of particulate pollution are introduced. This is followed by an illustration of the potential of modern Raman LIDARs, particularly when measurements are made with a network of systems on a con- tinental scale.