Download or read book Polycyclic Aromatic Hydrocarbons and Astrophysics written by A. Léger and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 405 pages. Available in PDF, EPUB and Kindle. Book excerpt: The near Infra-Red emission of the Interstellar Medium is a very puzzling subject. In the brightest regions, where spectroscopic observa tions are possible from the ground, several bands (3.3 - 3.4 - 6.2 - 7.7 - 8.6 - 11.3 ~m) have been observed since 1973. The absence of satisfying explanation was so obvious that they were called "Unidenti fied IR Emission Bands". The puzzle still increased when were known the first results of the general IR sky survey made by the satellite IRAS. On a large scale, the near IR emission of the Interstellar medium was expected to be very small but it was observed to be about one third of the total IR emission for our own galaxy ..• The situation has moved in 1984 when it was suggested that a class of stable organic molecules, the Polycyclic Aromatic Hydrocarbons (PAH's) could be at the origin of this near IR emission. Initially based on the required refractory character of particules that should be heated to high temperature without subliming, this hypothesis leads to a sugges tive spectroscopic similarity with the observed astronomical bands. This hypothesis is attractive and it has many implications, for ins tance, the PAHs would be the most abundant organic molecules in the universe. However, many points have to be clarified and the different consequences of this suggestion should be explored.
Download or read book The Physics and Chemistry of the Interstellar Medium written by A. G. G. M. Tielens and published by Cambridge University Press. This book was released on 2005-08-25 with total page 520 pages. Available in PDF, EPUB and Kindle. Book excerpt: Publisher Description
Download or read book PAHs and the Universe written by Christine Joblin and published by . This book was released on 2021 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Driven by ground-based, airborne, and IRAS observations, the PAH hypothesis was first formulated in the mid-eighties : the widespreas emission features in the 3-13 μm range are due to UV-pumped, IR fluorescence by large Polycyclic Aromatic Hydrocarbon molecules. These molecules are a ubiquitous component of the insterstellar medium both in local galaxies as well as out to redshifts of ~3 and probably beyond, play an important role in its physical and chemical characteristics, and form a key link between small hydrocarbon species and large carbonaceous grains. This book gathers contributions that reflect the evolution of the field over the last 25 years, taking advantage of IR space missions - ISO, Spitzer and AKARI - and of dedicated experimental and quantum-chemical studies. We have now reached a stage where we can develop these mid-infrared features as diagnostic tools to study star formation processes, protoplanetary disks as well as galaxy assemblage in the early Universe. The current Herschel/Planck area opens the possibility to better characterize the mid-IR carriers through their contribution to the far-IR and mm emissions. Still, much effort is required before we will fully understand the formation and nature of interstellar PAHs and their role in the Universe. Physical chemists can play an important role in driving this field. This book aims at discussing the state-of-the-art of the PAH hypothesis and to chart the future in this interdisciplinary field. It highlights the various aspects of interstellar PAHs: - Rich IR spectra of interstellar PAHs - PAHs and star formation in the near and far Universe - The lifecycle of PAHs in space - PAHs in regions of planet formation - PAHs and carbonaceous grains & Solar system materials.
Download or read book Evolution of Polycyclic Aromatic Hydrocarbons in the Interstellar Space written by Andrew Joseph and published by . This book was released on 2018-05-27 with total page 202 pages. Available in PDF, EPUB and Kindle. Book excerpt: The space between stars within galaxies is not empty; it is filled with gas and dust. Polycyclic aromatic hydrocarbons (PAHs) are one of the most complex organic species found in space. Over the past 20 years it has become increasingly clear that we live in a molecular universe: Molecules are directly interwoven into the fabric of the universe.Multiple formation mechanisms are discussed for interstellar PAHs, both in and ex situ. These pertain to molecular clouds and stellar ejecta, for which physical parameters vary largely. In the stellar ejecta of carbon-rich Asymptotic Giant Branch stars, terrestrial-combustion-like chemical reactions are more likely to take place, of which the products can be transported to the interstellar medium (ISM) by interstellar wind.One of the aims of this book is also to extensively discuss PAHs impact on the environment and the magnitude of the human health risks posed by such substances. It also contains important information on concentrations, burdens and fate of polycyclic aromatic hydrocarbons (PAHs) in the atmosphere.This book is designed for students of Astrophysics, Environmental Science, Environmental chemistry, Astronomy enthusiast, Health and safety professional and other professionals who wants to increase or update their knowledge in the area of polycyclic aromatic hydrocarbons and the interstellar space.
Download or read book The Diffuse Interstellar Bands written by A.G.G.M. Tielens and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 402 pages. Available in PDF, EPUB and Kindle. Book excerpt: The mystery of the diffuse interstellar bands has been variously a curiosity, a co nundrum, and a nuisance for astronomers in the seven decades since the features were first noticed, but recently they have become a forefront issue in astrophysics. Ever since Paul Merrill, in a series of papers starting in 1934, pointed out the interstellar and unidentified nature of the bands, a Who's Who of twentieth century astronomers have tried their hands at solving the problem of identifying the carriers. Henry Norris Russell, Pol Swings, Otto Struve, Paul Ledoux, W. W. Morgan, Walter Adams, Jesse Greenstein, Lawrence Aller, and Gerhard Herzberg all briefly entered the stage, only to move on quickly to other problems where the chances for progress appeared more realistic. In more recent times a number of equally prominent scientists have pursued the bands, but generally only as a sideline to their real astronomical research. But in the past decade, and particularly in the past three years, the view of the search for the diffuse band absorbers as an interesting but perhaps quixotic quest has changed. Today there are several astronomers, as well as laboratory chemists, who are devoting substantial research time and resources to the problem and, as perhaps the most reliable indicator of the newly elevated status of research in this field, some research grants have now been awarded for the study of the bands.
Download or read book Fourier Transform Ion Cyclotron Resonance Mass Spectrometry Investigation of the Photolysis of Polycyclic Aromatic Hydrocarbons written by Mark J. Dibben and published by . This book was released on 2001-01-01 with total page 160 pages. Available in PDF, EPUB and Kindle. Book excerpt: Of the many problems currently being tackled by astrophysicists, two are of particular interest to spectroscopists and molecular physicists. These are emission observed from numerous objects in the infrared region in the interstellar medium and the absorption seen in the near infrared and visible regions. It is generally accepted that the species giving rise to these spectral features are gaseous molecules (or radical or ions), and not dust particles or grains. Polycyclic aromatic hydrocarbons (PAHs) are one class of molecules which have been proposed as carriers of these features. In this dissertation, the effect of visible/UV irradiation on several PAHs is studied in detail. FT-ICR mass spectrometry was used to determine the photolysis products of the ionized PAHs fluorene, naphthalene and 1,2-benzanthracene in the vapor phase by irradiation with a xenon arc lamp. Products of ion-molecule reactions were also characterized for all three PAHs. Broad-band visible and ultraviolet irradiation of ionized fluorene for relatively short times (^0.5s) is shown to lead predominantly to sequential hydrogen atom loss, with one to five hydrogens lost. Rate constants and branching ratios for the photodecomposition of the fluorene parent ion and its dehydrogenated partners have been determined. Longer irradiation times lead to various products resulting from multiple C-C bond cleavages. Density functional calculations are used to show dehydrogenation first occurs from the sp(sup 3) carbon on the five-membered ring and then from only one of the six membered rings. Possible geometries have been calculated for all of the photoproducts. Aggregates are shown to form from the fluorene fragments reacting with neutral molecules. These aggregates are fairly stable except for dehydrogenation and slight acetylene fragmentation. Irradiation of the naphthalene ion for short times resulted in a maximum loss of two hydrogens.
Download or read book Aromatic Polycyclic Hydrocarbons Advances in Research and Application 2012 Edition written by and published by ScholarlyEditions. This book was released on 2012-12-26 with total page 413 pages. Available in PDF, EPUB and Kindle. Book excerpt: Aromatic Polycyclic Hydrocarbons—Advances in Research and Application: 2012 Edition is a ScholarlyEditions™ eBook that delivers timely, authoritative, and comprehensive information about Aromatic Polycyclic Hydrocarbons. The editors have built Aromatic Polycyclic Hydrocarbons—Advances in Research and Application: 2012 Edition on the vast information databases of ScholarlyNews.™ You can expect the information about Aromatic Polycyclic Hydrocarbons in this eBook to be deeper than what you can access anywhere else, as well as consistently reliable, authoritative, informed, and relevant. The content of Aromatic Polycyclic Hydrocarbons—Advances in Research and Application: 2012 Edition has been produced by the world’s leading scientists, engineers, analysts, research institutions, and companies. All of the content is from peer-reviewed sources, and all of it is written, assembled, and edited by the editors at ScholarlyEditions™ and available exclusively from us. You now have a source you can cite with authority, confidence, and credibility. More information is available at http://www.ScholarlyEditions.com/.
Download or read book Investigating the Formation Mechanism of Polycyclic Aromatic Hydrocarbons and Adapting Particle Swarm Optimization Techniques to Search Large Data Sets written by Daniel P. Caputo and published by . This book was released on 2010 with total page 86 pages. Available in PDF, EPUB and Kindle. Book excerpt: The unidentified infrared bands (UIBs) have been attributed to emission from polycyclic aromatic hydrocarbons (PAHs). The UIBs at 3.3 and 11.3 [mu]m, among others, are seen in many astrophysical environments, with the notable exception of carbon-rich AGB stars (C stars). PAHs are expected to form around C stars, yet only a few show the UIBs and all of these have hot companions. This makes C stars with hot companions an ideal environment to study the conditions associated with PAH formation and processing. We present new observations, taken using the Gemini North telescope, of several C stars with hot companions in order to understand the distribution of PAHs responsible for the emerging UIB emission. As the size of data and model sets continue to increase, more efficient ways are needed to sift through the available information. We also present a computational method which will efficiently search large parameter spaces to either map the space or find individual data/models of interest. This is done through a heavily modified Particle Swarm Optimization algorithm.
Download or read book Bioaccumulation in Marine Organisms written by J.M. Neff and published by Elsevier. This book was released on 2002-04-16 with total page 469 pages. Available in PDF, EPUB and Kindle. Book excerpt: Large volumes of produced water are generated and discharged to the coastal and ocean waters worldwide from offshore oil and gas production facilities. There is concern that the chemicals in the produced water may harm marine ecosystems. This book summarizes the bioavailability and marine ecotoxicology of metal and organic contaminants that may occur in oil well produced water at concentrations significantly higher than those in ambient seawater. The contaminants of concern include arsenic, barium, cadmium, chromium, copper, lead, mercury, radium isotopes, zinc, monocyclic aromatic hydrocarbons, polycyclic aromatic hydrocarbons, phenols, and bis(2-ethylhexyl)phthalate.The first part of the book is a detailed discussion of the chemical composition of produced water from offshore oil wells worldwide and its fates following discharge to the ocean. The remaining chapters of the book summarize the current scientific literature on the sources and distributions in the ocean of each of the contaminants of concern and their bioaccumulation and toxicity to marine organisms.This book will be of value to: environmental scientists in the oil and gas industry; marine toxicologists and ecological risk assessors in academia, government, and industry; government regulatory agencies concerned with marine environmental protection.The book advances the concept that bioavailability evaluation must be included in all ecological risk assessments and other environmental assessments of chemical contaminants in marine and freshwater ecosystems.
Download or read book Theory and Applications of Computational Chemistry written by Clifford Dykstra and published by Elsevier. This book was released on 2011-10-13 with total page 1336 pages. Available in PDF, EPUB and Kindle. Book excerpt: Computational chemistry is a means of applying theoretical ideas using computers and a set of techniques for investigating chemical problems within which common questions vary from molecular geometry to the physical properties of substances. Theory and Applications of Computational Chemistry: The First Forty Years is a collection of articles on the emergence of computational chemistry. It shows the enormous breadth of theoretical and computational chemistry today and establishes how theory and computation have become increasingly linked as methodologies and technologies have advanced. Written by the pioneers in the field, the book presents historical perspectives and insights into the subject, and addresses new and current methods, as well as problems and applications in theoretical and computational chemistry. Easy to read and packed with personal insights, technical and classical information, this book provides the perfect introduction for graduate students beginning research in this area. It also provides very readable and useful reviews for theoretical chemists. * Written by well-known leading experts * Combines history, personal accounts, and theory to explain much of the field of theoretical and compuational chemistry * Is the perfect introduction to the field
Download or read book Astrophysics of Dust written by Adolf N. Witt and published by . This book was released on 2004 with total page 880 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Laboratory Astrophysics written by Guillermo M. Muñoz Caro and published by Springer. This book was released on 2018-10-11 with total page 237 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book focuses on the most recent, relevant, comprehensive and significant aspects in the well-established multidisciplinary field Laboratory Astrophysics. It focuses on astrophysical environments, which include asteroids, comets, the interstellar medium, and circumstellar and circumplanetary regions. Its scope lies between physics and chemistry, since it explores physical properties of the gas, ice, and dust present in those systems, as well as chemical reactions occurring in the gas phase, the bare dust surface, or in the ice bulk and its surface. Each chapter provides the necessary mathematical background to understand the subject, followed by a case study of the corresponding system. The book provides adequate material to help interpret the observations, or the computer models of astrophysical environments. It introduces and describes the use of spectroscopic tools for laboratory astrophysics. This book is mainly addressed to PhD graduates working in this field or observers and modelers searching for information on ice and dust processes.
Download or read book Laboratory Spectra of Polycyclic Aromatic Hydrocarbon Cations in the Vacuum Ultraviolet written by Michael S. Robinson and published by . This book was released on 1996 with total page 246 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Advances in Food and Nutrition Research written by and published by Academic Press. This book was released on 2017-03-17 with total page 332 pages. Available in PDF, EPUB and Kindle. Book excerpt: Approx.318 pagesApprox.318 pages
Download or read book Soot Formation in Combustion written by Henning Bockhorn and published by Springer Science & Business Media. This book was released on 2013-03-08 with total page 595 pages. Available in PDF, EPUB and Kindle. Book excerpt: Soot Formation in Combustion represents an up-to-date overview. The contributions trace back to the 1991 Heidelberg symposium entitled "Mechanism and Models of Soot Formation" and have all been reedited by Prof. Bockhorn in close contact with the original authors. The book gives an easy introduction to the field for newcomers, and provides detailed treatments for the specialists. The following list of contents illustrates the topics under review:
Download or read book Astrochemistry written by Andrew M. Shaw and published by John Wiley & Sons. This book was released on 2007-01-11 with total page 352 pages. Available in PDF, EPUB and Kindle. Book excerpt: The dynamic field of astrochemistry brings together ideas of physics, astrophysics, biology and chemistry to the study of molecules between stars, around stars and on planets. Astrochemistry: from Astronomy to Astrobiology provides a clear and concise introduction to this rapidly evolving multidisciplinary subject. Starting with the Molecular Universe, the text covers the formation of the elements, simple models of stars and their classification. It then moves on to draw on the theme of the Origins of Life to study interstellar chemistry, meteorite and comet chemistry as well as the chemistry of planets. Prebiotic chemistry and astrobiology are explored by examining the extremes of the biosphere on Earth, seeing how this may be applied to life in other solar systems. Astrochemsitry assumes a basic familiarity with principles of physical and organic chemistry but no prior knowledge of biology or astrophysics. This innovative text incorporates results from the latest research and ground and space missions, with key images enhanced by a colour plate section. includes latest research and results from ground and space missions colour plate section summary of concepts and calculations at the end of each chapter accompanying website www.wiley.co/go/shawastrochemistry This book will be an ideal text for an undergraduate course in Astrochemistry and an essential tool for postgraduates entering the field.
Download or read book Radiative Processes in Astrophysics written by George B. Rybicki and published by John Wiley & Sons. This book was released on 2008-09-26 with total page 400 pages. Available in PDF, EPUB and Kindle. Book excerpt: Radiative Processes in Astrophysics: This clear, straightforward, and fundamental introduction is designed to present-from a physicist's point of view-radiation processes and their applications to astrophysical phenomena and space science. It covers such topics as radiative transfer theory, relativistic covariance and kinematics, bremsstrahlung radiation, synchrotron radiation, Compton scattering, some plasma effects, and radiative transitions in atoms. Discussion begins with first principles, physically motivating and deriving all results rather than merely presenting finished formulae. However, a reasonably good physics background (introductory quantum mechanics, intermediate electromagnetic theory, special relativity, and some statistical mechanics) is required. Much of this prerequisite material is provided by brief reviews, making the book a self-contained reference for workers in the field as well as the ideal text for senior or first-year graduate students of astronomy, astrophysics, and related physics courses. Radiative Processes in Astrophysics also contains about 75 problems, with solutions, illustrating applications of the material and methods for calculating results. This important and integral section emphasizes physical intuition by presenting important results that are used throughout the main text; it is here that most of the practical astrophysical applications become apparent.
