Download or read book Unimolecular Decay Dynamics of Atmospherically Important Criegee Intermediates written by Yi Fang and published by . This book was released on 2017 with total page 602 pages. Available in PDF, EPUB and Kindle. Book excerpt: In the atmosphere, the gas-phase reactions of ozone with biogenic and anthropogenic alkenes are significant sources of hydroxyl (OH) radicals, which are often termed the atmosphere's detergent. Alkene ozonolysis proceeds through energized carbonyl oxide species, known as Criegee intermediates, that can undergo unimolecular decay to OH radical products. Jet-cooled stabilized Criegee intermediates are investigated to obtain their unimolecular decay dynamics upon ultraviolet (UV) and infrared (IR) excitation in a collision-free environment. The UV dissociation dynamics of CH2OO and syn-CH3CHOO are investigated using the velocity map imaging technique to characterize the velocity and angular distributions of the oxygen-atom products. IR activation of prototypical alky-substituted Criegee intermediates (syn-CH3CHOO, (CH3) 2COO and CH3CH2CHOO) is used to drive hydrogen atom transfer from the methyl group (or -CH2-) to the terminal oxygen, followed by unimolecular decay to OH radicals, which are detected by UV laser-induced fluorescence. The OH appearance time profiles are obtained by varying the IR pump--UV probe time delay. Unimolecular decay rates are measured upon vibrationally activation of syn-CH 3CHOO, (CH3)2COO and CH3CH2CHOO in the vicinity of the transition state (TS) barriers. In addition, the unimolecular decay of syn-CH3CHOO and (CH3) 2COO to OH products is shown to occur at energies significantly below the TS barriers. Initiation of the hydrogen transfer process at these lower energies provides a stringent test of quantum mechanical tunneling effects in the unimolecular decay rates. The measured experimental rates for syn-CH3CHOO and (CH3)2COO in this deep tunneling regime are approximately 100 times slower than those in the vicinity of the TS barriers. The experimental results are in very good accord with statistical Rice-Ramsperger-Kassel-Marcus calculations of the microcanonical decay rates with tunneling through the TS barrier. Thermal unimolecular decay rates for alkyl-substituted Criegee intermediates are predicted from energy-dependent microcanonical decay rates, and are found to have significant contribution from energies that are much below the TS barrier.

Download or read book Photo induced Dissociation Dynamics of Atmospherically Significant Criegee Intermediates written by Hongwei Li and published by . This book was released on 2016 with total page 462 pages. Available in PDF, EPUB and Kindle. Book excerpt: Alkene ozonolysis, which proceeds through energized carbonyl oxide species also known as Criegee intermediates, is an important oxidation process for atmospheric alkenes and a significant source of hydroxyl (OH) radicals in the troposphere. Criegee intermediates (CH2OO, CH3CHOO, (CH3)2COO) are synthesized by the reaction of iodoalkyl radicals with molecular oxygen in a quartz capillary reactor, cooled in a free jet expansion, and characterized through ultraviolet (UV) and/or infrared (IR) induced dynamical studies. The dissociation dynamics of CH2I2 is investigated using velocity map imaging (VMI) to obtain the velocity distribution of the iodine atom products. The corresponding high internal excitation of the CH2I co-fragments provides insight into the internal excitation of newly formed CH2OO in the subsequent thermo-neutral CH2I + O2 reaction. UV excitation of CH2OO and CH3CHOO on a very strong pi* → pi transition localized in the carbonyl oxide group is shown to result in O-O bond breakage. Both ground O 3P and excited O 1D state products are characterized using VMI to obtain the angular and velocity distributions of the O-atom products. Anisotropic angular distributions of the O-atom products show the rapid nature of the UV photodissociation dynamics. The total kinetic energy distributions reveal the energy required for dissociation into two spin-allowed channels as well as the high degree of internal excitation of the co-fragments. Finally, IR activation of syn-CH3CHOO and (CH3)2COO is utilized to access the barrier to 1,4-hydrogen transfer, which initiates unimolecular decay to OH radical products. The OH fragments are examined using a novel implementation of VMI based on UV+VUV ionization. IR excitation of syn-CH3CHOO and (CH3)2COO in the CH stretch overtone region results in an isotropic angular distribution of OH fragments, indicating that dissociation occurs more slowly than the rotational period of Criegee intermediates. The OH products are released with little internal excitation, while the total kinetic energy release demonstrates that most of the available energy flows into internal excitation of the vinoxy or 1-methlvinoxy co-fragments. The experimental results are compared with quasi-classical trajectory calculations initiated at critical configurations along the reaction pathway and statistical Prior distributions.

Download or read book Tableaux Objets d art et de bel ameublement Bijoux Orf vrerie ancienne written by and published by . This book was released on 1970 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Unimolecular Reaction Dynamics written by Tomas Baer and published by Oxford University Press. This book was released on 1996-06-27 with total page 447 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book provides a penetrating and comprehensive description of energy selected reactions from a theoretical as well as experimental view. Three major aspects of unimolecular reactions involving the preparation of the reactants in selected energy states, the rate of dissociation of the activated molecule, and the partitioning of the excess energy among the final products, are fully discussed with the aid of 175 illustrations and over 1,000 references, most from the recent literature. Examples of both neutral and ionic reactions are presented. Many of the difficult topics are discussed at several levels of sophistication to allow access by novices as well as experts. Among the topics covered for the first time in monograph form is a discussion of highly excited vibrational/rotational states and intramolecular vibrational energy redistribution. Problems associated with the application of RRKM theory are discussed with the aid of experimental examples. Detailed comparisons are also made between different statistical models of unimolecular decomposition. Both quantum and classical models not based on statistical assumptions are described. Finally, a chapter devoted to the theory of product energy distribution includes the application of phase space theory to the dissociation of small and large clusters. The work will be welcomed as a valuable resource by practicing researchers and graduate students in physical chemistry, and those involved in the study of chemical reaction dynamics.

Download or read book Mechanisms of Atmospheric Oxidation of the Alkanes written by Jack G Calvert and published by Oxford University Press. This book was released on 2008-09-15 with total page 1005 pages. Available in PDF, EPUB and Kindle. Book excerpt: An international team of eminent atmospheric scientists have prepared Mechanisms of Atmospheric Oxidation of the Alkanes as an authoritative source of information on the role of alkanes in the chemistry of the atmosphere. The book includes the properties of the alkanes and haloalkanes, as well as a comprehensive review and evaluation of the existing literature on the atmospheric chemistry of the alkanes and their major atmospheric oxidation products, and the various approaches now used to model the alkane atmospheric chemistry. Comprehensive coverage is given of both the unsubstituted alkanes and the many haloalkanes. All the existing quality measurements of the rate coefficients for the reactions of OH, Cl, O(3P), NO3, and O3 with the alkanes, the haloalkanes, and their major oxidation products have been reviewed and evaluated. The expert authors then give recommendations of the most reliable kinetic data. They also review the extensive literature on the mechanisms and rates and modes of photodecomposition of the haloalkanes and the products of atmospheric oxidation of the alkanes and the haloalkanes, and make recommendations for future use by atmospheric scientists. The evaluations presented allow an extrapolation of the existing kinetic and photochemical data to those alkanes and haloalkanes that are as yet unstudied. The current book should be of special interest and value to the modelers of atmospheric chemistry as a useful input for development of realistic modules designed to simulate the atmospheric chemistry of the alkanes, their major oxidation products, and their influence on ozone and other trace gases within the troposphere.

Download or read book Air Pollution the Automobile and Public Health written by Sponsored by The Health Effects Institute and published by National Academies Press. This book was released on 1988-01-01 with total page 703 pages. Available in PDF, EPUB and Kindle. Book excerpt: "The combination of scientific and institutional integrity represented by this book is unusual. It should be a model for future endeavors to help quantify environmental risk as a basis for good decisionmaking." â€"William D. Ruckelshaus, from the foreword. This volume, prepared under the auspices of the Health Effects Institute, an independent research organization created and funded jointly by the Environmental Protection Agency and the automobile industry, brings together experts on atmospheric exposure and on the biological effects of toxic substances to examine what is knownâ€"and not knownâ€"about the human health risks of automotive emissions.

Download or read book Spectroscopy and Kinetics written by James S. Mattson and published by Marcel Dekker. This book was released on 1973 with total page 364 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Multiconfigurational Quantum Chemistry written by Björn O. Roos and published by John Wiley & Sons. This book was released on 2016-08-08 with total page 240 pages. Available in PDF, EPUB and Kindle. Book excerpt: The first book to aid in the understanding of multiconfigurational quantum chemistry, Multiconfigurational Quantum Chemistry demystifies a subject that has historically been considered difficult to learn. Accessible to any reader with a background in quantum mechanics and quantum chemistry, the book contains illustrative examples showing how these methods can be used in various areas of chemistry, such as chemical reactions in ground and excited states, transition metal and other heavy element systems. The authors detail the drawbacks and limitations of DFT and coupled-cluster based methods and offer alternative, wavefunction-based methods more suitable for smaller molecules.

Download or read book Theory of Unimolecular Reactions written by Wendell Forst and published by Elsevier. This book was released on 2012-12-02 with total page 464 pages. Available in PDF, EPUB and Kindle. Book excerpt: Theory of Unimolecular Reactions provides a comprehensive analysis of the theory of unimolecular reactions, also known to kineticists as the Rice-Marcus or the Rice-Ramsperger-Kassel-Marcus theory, and to those working in mass spectrometry and related fields as the quasi-equilibrium theory or the theory of mass spectra. This book demonstrates how theoretical parameters are related to experimental observables and describes the methods that are used to obtain useful numerical answers. This monograph consists of 11 chapters and begins by explaining the derivation of the expression for the basic rate k(E), with emphasis on the unimolecular rate constant, intramolecular energy transfer, and potential energy surfaces in unimolecular reactions. The statistical calculation of unimolecular rate under vibrational potential is also given, along with pertinent degrees of freedom. The remaining chapters explore the energy distribution functions appropriate to each system, the averaging of k(E), and the relations between theoretical and experimental parameters. Thermal reactions, chemical activation systems, and the theory of mass spectra are examined. The last chapter is devoted to the transition state and its ambiguities. This text will be of interest to gas kineticists, mass spectrometrists, and students and researchers working in the field of physical chemistry.

Download or read book Active Oxygen in Chemistry written by Christopher S. Foote and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 355 pages. Available in PDF, EPUB and Kindle. Book excerpt: Taking an interdisciplinary approach, this book and its counterpart, Active Oxygen in Biochemistry, explore the active research area of the chemistry and biochemistry of oxygen. Complementary but independent, the two volumes integrate subject areas including medicine, biology, chemistry, engineering, and environmental studies.

Download or read book Atmospheric Chemistry and Physics written by John H. Seinfeld and published by John Wiley & Sons. This book was released on 2012-12-18 with total page 1249 pages. Available in PDF, EPUB and Kindle. Book excerpt: Thoroughly restructured and updated with new findings and new features The Second Edition of this internationally acclaimed text presents the latest developments in atmospheric science. It continues to be the premier text for both a rigorous and a complete treatment of the chemistry of the atmosphere, covering such pivotal topics as: * Chemistry of the stratosphere and troposphere * Formation, growth, dynamics, and properties of aerosols * Meteorology of air pollution * Transport, diffusion, and removal of species in the atmosphere * Formation and chemistry of clouds * Interaction of atmospheric chemistry and climate * Radiative and climatic effects of gases and particles * Formulation of mathematical chemical/transport models of the atmosphere All chapters develop results based on fundamental principles, enabling the reader to build a solid understanding of the science underlying atmospheric processes. Among the new material are three new chapters: Atmospheric Radiation and Photochemistry, General Circulation of the Atmosphere, and Global Cycles. In addition, the chapters Stratospheric Chemistry, Tropospheric Chemistry, and Organic Atmospheric Aerosols have been rewritten to reflect the latest findings. Readers familiar with the First Edition will discover a text with new structures and new features that greatly aid learning. Many examples are set off in the text to help readers work through the application of concepts. Advanced material has been moved to appendices. Finally, many new problems, coded by degree of difficulty, have been added. A solutions manual is available. Thoroughly updated and restructured, the Second Edition of Atmospheric Chemistry and Physics is an ideal textbook for upper-level undergraduate and graduate students, as well as a reference for researchers in environmental engineering, meteorology, chemistry, and the atmospheric sciences. Click here to Download the Solutions Manual for Academic Adopters: http://www.wiley.com/WileyCDA/Section/id-292291.html

Download or read book Surface Water Photochemistry written by Paola Calza and published by Royal Society of Chemistry. This book was released on 2015-11-20 with total page 310 pages. Available in PDF, EPUB and Kindle. Book excerpt: Borne out of the current widespread interest in the pollution of water bodies, this book explores the latest research concerning the photochemical fate of organic pollutants in surface water. The main objective is to give insight into both the functioning of ecosystems and the behaviour of emerging pollutants in those ecosystems. Particular importance is dedicated to techniques that can be used in the field and in the laboratory for the detection of pollutants and of their transformation intermediates. The inclusion of photochemical processes that have not gained previous coverage will afford the reader novel insights, whilst the focus on modelling and transformation intermediates will ensure the title's relevance to academics, the chemical manufacturing industries and environmental assessment experts alike.

Download or read book Organic Peroxy Radicals written by P. D. Lightfoot and published by . This book was released on 1992 with total page 5 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book The Ozone Layer written by Guy Brasseur and published by . This book was released on 2020 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: From the discovery of ozone in the eighteenth century, through the late twentieth-century international agreements to protect humanity from the destruction of ozone in the stratosphere, Guy P. Brasseur traces the evolution of our scientific knowledge on air quality issues and stratospheric chemistry and dynamics. The history of ozone research is marked by typical examples of the scientific method at work, perfectly illustrating how knowledge progresses. Hypotheses are contested and then eventually accepted or rejected; truths once believed to be universal and permanent can be called into question; and debates and disagreements between scientists are settled by information from laboratory and field experiments. Of course, the scientific method can also lead to new observations--in this case, the discovery of the ozone hole. This finding took researchers by surprise, leading to new investigations and research programs. This first complete study of ozone research demonstrates the key role fundamental research plays in solving global environmental, climate, and human health problems. More importantly, it shows that the scientific method works. Convincing decision makers of research results that do not correspond to their values, or to the interests of certain business groups, stands to be the highest hurdle in using science to benefit humanity. Students, early-career scientists, and even specialists who do not know much about the history of their field will benefit from this big picture view, offered by a researcher who has played leadership roles in stewarding this science through decades of discovery.

Download or read book Advances in Chemical Engineering written by John H Seinfeld and published by Academic Press. This book was released on 1992-02-03 with total page 373 pages. Available in PDF, EPUB and Kindle. Book excerpt: Advances in Chemical Engineering

Download or read book Chemistry of the Upper and Lower Atmosphere written by Barbara J. Finlayson-Pitts and published by Elsevier. This book was released on 1999-11-17 with total page 993 pages. Available in PDF, EPUB and Kindle. Book excerpt: Here is the most comprehensive and up-to-date treatment of one of the hottest areas of chemical research. The treatment of fundamental kinetics and photochemistry will be highly useful to chemistry students and their instructors at the graduate level, as well as postdoctoral fellows entering this new, exciting, and well-funded field with a Ph.D. in a related discipline (e.g., analytical, organic, or physical chemistry, chemical physics, etc.). Chemistry of the Upper and Lower Atmosphere provides postgraduate researchers and teachers with a uniquely detailed, comprehensive, and authoritative resource. The text bridges the "gap" between the fundamental chemistry of the earth's atmosphere and "real world" examples of its application to the development of sound scientific risk assessments and associated risk management control strategies for both tropospheric and stratospheric pollutants. - Serves as a graduate textbook and "must have" reference for all atmospheric scientists - Provides more than 5000 references to the literature through the end of 1998 - Presents tables of new actinic flux data for the troposphere and stratospher (0-40km) - Summarizes kinetic and photochemical date for the troposphere and stratosphere - Features problems at the end of most chapters to enhance the book's use in teaching - Includes applications of the OZIPR box model with comprehensive chemistry for student use

Download or read book Atmospheric Multiphase Chemistry written by Hajime Akimoto and published by John Wiley & Sons. This book was released on 2020-06-02 with total page 539 pages. Available in PDF, EPUB and Kindle. Book excerpt: An important guide that highlights the multiphase chemical processes for students and professionals who want to learn more about aerosol chemistry Atmospheric Multiphase Reaction Chemistry provides the information and knowledge of multiphase chemical processes and offers a review of the fundamentals on gas-liquid equilibrium, gas phase reactions, bulk aqueous phase reactions, and gas-particle interface reactions related to formation of secondary aerosols. The authors—noted experts on the topic—also describe new particle formation, and cloud condensation nuclei activity. In addition, the text includes descriptions of field observations on secondary aerosols and PM2.5. Atmospheric aerosols play a critical role in air quality and climate change. There is growing evidence that the multiphase reactions involving heterogeneous reactions on the air-particle interface and the reactions in the bulk liquid phase of wet aerosol and cloud/fog droplets are important processes forming secondary aerosols in addition to gas-phase oxidation reactions to form low-volatile compounds. Comprehensive in scope, the book offers an understanding of the topic by providing a historical overview of secondary aerosols, the fundamentals of multiphase reactions, gas-phase reactions of volatile organic compounds, aqueous phase and air-particle interface reactions of organic compound. This important text: Provides knowledge on multiphase chemical processes for graduate students and research scientists Includes fundamentals on gas-liquid equilibrium, gas phase reactions, bulk aqueous phase reactions, and gas-particle interface reactions related to formation of secondary aerosols Covers in detail reaction chemistry of secondary organic aerosols Written for students and research scientists in atmospheric chemistry and aerosol science of environmental engineering, Atmospheric Multiphase Reaction Chemistry offers an essential guide to the fundamentals of multiphase chemical processes.