Download or read book Spectroscopy and Chemical Kinetics of Formaldehyde Oxide CH2OO Using Time resolved Broadband Cavity enhanced Absorption Spectroscopy written by and published by . This book was released on 2013 with total page 1 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Direct Spectroscopic and Kinetic Studies of the Simplest Criegee Intermediate written by Elizabeth Stack Foreman and published by . This book was released on 2017 with total page 167 pages. Available in PDF, EPUB and Kindle. Book excerpt: Atmospheric chemistry is driven largely by free radical species whose reactions determine both the composition and oxidative capacity of the atmosphere. Carbonyl oxides, or Criegee Intermediates, formed in the ozonolysis of alkenes in the troposphere are highly reactive biradicals/zwitterions that are implicated in the production of secondary organic aerosol and particulate matter. This thesis will focus on the following aspects of the spectroscopy and kinetics related to the simplest Criegee Intermediate, formaldehyde oxide: (1) kinetics of IO radical formation from the CH2I + O2 reaction, (2) spectroscopy and dynamics of electronically excited states of CH 2OO, (3) the kinetics of reactions of CH2OO with trace atmospheric pollutants. The spectroscopic and kinetic study of IO radicals formed as minor products in the laboratory synthesis of Criegee Intermediates is performed using cavity ring-down spectroscopy (CRDS). We observe experimentally that IO radicals exhibit vibrational state specific formation kinetics and suggest that this is due to a product branching ratio controlled by the degree of internal excitation in the reactants. IO and CH2OO are produced simultaneously in the reaction of CH2I with O2 and exhibit overlapping absorption bands in the near-ultraviolet/visible. This poses a challenge for direct detection of CH2OO using a linear absorption technique. The measured rate constant for the formation of IO is used to deconvolute the total observed absorption spectrum into individual molecular components. Both CRDS and single-pass broadband transient absorption spectroscopy (BBTAS) are used to independently measure the absolute absorption cross sections for the second electronically excited state of CH2OO in the near-ultraviolet/visible. We show that the absorption spectra do not exhibit fine structure, even at the lowest excitation energies, and that the observed broad lineshapes cannot be attributed hot bands. This suggests that the photolysis quantum yield is “1 and the observed structure in the electronic absorption spectrum, that is absent from the action spectrum, is the result of relaxation via nonradiative population transfer to a long-lived state or fluorescence. BBTAS is subsequently used to probe the kinetics of the reactions of CH2OO with two inorganic acids: HCl and HNO3. We find that these reactions occur at or near the collision limit and that nitric acid in particular may be locally competitive with water vapor, which is widely accepted as the dominant sink for Criegee Intermediates in the atmosphere. Taken together these studies provide a deeper understanding of the role Criegee Intermediates play in tropospheric chemistry.
Download or read book Reaction Kinetics of a Prototypical Criegee Intermediate Formaldehyde Oxide CH2OO with Isoprene written by and published by . This book was released on 2015 with total page 1 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book High Resolution Studies of the 1A2 X 1A1Electronic Transition of Formaldehyde written by Cheryl Tatum Ernest and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Formaldehyde (HCHO) plays a primary role in tropospheric chemistry. Its photochemical activity is an important source of radical species such as HCO, H, and subsequently HO2 as well as molecular hydrogen and carbon monoxide. As a source of hydrogen radicals (HOx = OH + HO2), HCHO plays a significant role in the oxidative capacity of the atmosphere, and an important part in the interrelated chemistries of ozone and the HOx and NOx (NO + NO2) cycles. Accurate atmospheric photolysis rates of HCHO are thus required in order to properly model tropospheric chemistry. Despite extensive studies HCHO's spectroscopy and photochemistry remains to be well characterized. Absolute room temperature absorption cross sections for the A1A2 -- X1A1 electronic transition of formaldehyde have been measured over the spectral range 30285 -- 32890 cm-1 (304 -- 330 nm) using ultraviolet (UV) laser absorption spectroscopy. Absorption cross sections were obtained at an instrumental resolution better than 0.09 cm-1 which is slightly broader than the Doppler width of a rotational line of HCHO at 300K (~0.07 cm-1) and so we were able to resolve all but the most closely spaced lines. Qualitative comparisons with spectral simulations show varying agreement depending on vibronic band. Refined state origins and transition dipole moments for each vibronic band have been reported. There is evidence of areas of perturbation and the need to optimize higher order spectral constants. Pressure broadening parameters have been measured and increase with the strength of intermolecular interaction between formaldehyde and the collision partner. Comparisons between the available high-resolution studies and spectral simulations indicate that the HCHO absorption cross section is still not well characterized. The relative quantum yield for the production of radical products, H+HCO, from the UV photolysis of formaldehyde (HCHO) has been measured directly using a Pulsed Laser Photolysis -- Pulsed Laser Induced Fluorescence (PLP -- PLIF) technique across the same spectral region. Relative yields were normalized to a value of 0.69 at 31750 cm-1 based on the current NASA-JPL recommendation. The resulting absolute radical quantum yields agree well with previous experimental studies and show more wavelength dependent behavior than the recommendation. This provides support for the complicated competition among the various HCHO dissociation pathways.
Download or read book Time resolved Four wave Mixing Spectroscopy of Gaseous Formaldehyde written by Andreas Markus Walser and published by . This book was released on 2008 with total page 135 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book High resolution Spectroscopy of Formaldehyde written by Martin Zeppenfeld and published by . This book was released on 2006 with total page 75 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Advances in Spectroscopic Monitoring of the Atmosphere written by Weidong Chen and published by Elsevier. This book was released on 2021-06-09 with total page 634 pages. Available in PDF, EPUB and Kindle. Book excerpt: Advances in Spectroscopic Monitoring of the Atmosphere provides a comprehensive overview of cutting-edge technologies and monitoring applications. Concepts are illustrated by numerous examples with information on spectroscopic techniques and applications widely distributed throughout the text. This information is important for researchers to gain an overview of recent developments in the field and make informed selections among the most suitable techniques. This volume also provides information that will allow researchers to explore implementing and developing new diagnostic tools or new approaches for trace gas and aerosol sensing themselves. Advances in Spectroscopic Monitoring of the Atmosphere covers advanced and newly emerging spectroscopic techniques for optical metrology of gases and particles in the atmosphere. This book will be a valuable reference for atmospheric scientists, including those whose focus is applying the methods to atmospheric studies, and those who develop instrumentation. It will also serve as a useful introduction to researchers entering the field and provide relevant examples to researchers and students developing and applying optical sensors for a variety of other scientific, technical, and industrial uses. - Overview of new applications including remote sensing by UAV, laser heterodyne radiometry, dual comb spectroscopy, and more - Features in-situ observations and measurements for real-world data - Includes content on leading edge optical sensors
Download or read book Energy Dissipation in Molecular Systems written by André Tramer and published by Springer Science & Business Media. This book was released on 2005-03-29 with total page 220 pages. Available in PDF, EPUB and Kindle. Book excerpt: Only a basic knowledge of quantum mechanics and spectroscopy is required of the reader and calculations are reduced to a strict minimum, making the book accessible to students."--Jacket.
Download or read book Spectral Line Formation written by John T. Jefferies and published by . This book was released on 1968 with total page 328 pages. Available in PDF, EPUB and Kindle. Book excerpt: The purpose of this book is to discuss certain aspects of the theory of the formation and analysis of the line spectrum of a hot gas. The underlying motivation for most of the studies discussed here lies in a desire to develop a physically sound procedure for interpreting the line spectrum of a stellar atmosphere ; correspondingly, the major emphasis is given to problems encountered in astrophysics.
Download or read book Molecular Structure and Dynamics written by W. H. Flygare and published by Prentice Hall. This book was released on 1978 with total page 728 pages. Available in PDF, EPUB and Kindle. Book excerpt: Good,No Highlights,No Markup,all pages are intact, Slight Shelfwear,may have the corners slightly dented, may have slight color changes/slightly damaged spine.
Download or read book Dorland s Dictionary of Medical Acronyms and Abbreviations written by Dorland and published by Elsevier Health Sciences. This book was released on 2015-07-24 with total page 481 pages. Available in PDF, EPUB and Kindle. Book excerpt: Medical acronyms and abbreviations offer convenience, but those countless shortcuts can often be confusing. Now a part of the popular Dorland's suite of products, this reference features thousands of terms from across various medical specialties. Its alphabetical arrangement makes for quick reference, and expanded coverage of symbols ensures they are easier to find. Effective communication plays an important role in all medical settings, so turn to this trusted volume for nearly any medical abbreviation you might encounter. - Symbols section makes it easier to locate unusual or seldom-used symbols. - Convenient alphabetical format allows you to find the entry you need more intuitively. - More than 90,000 entries and definitions. - Many new and updated entries including terminology in expanding specialties, such as Nursing; Physical, Occupational, and Speech Therapies; Transcription and Coding; Computer and Technical Fields. - New section on abbreviations to avoid, including Joint Commission abbreviations that are not to be used. - Incorporates updates suggested by the Institute for Safe Medication Practices (ISMP).
Download or read book Cleaner Combustion written by Frédérique Battin-Leclerc and published by Springer Science & Business Media. This book was released on 2013-09-06 with total page 657 pages. Available in PDF, EPUB and Kindle. Book excerpt: This overview compiles the on-going research in Europe to enlarge and deepen the understanding of the reaction mechanisms and pathways associated with the combustion of an increased range of fuels. Focus is given to the formation of a large number of hazardous minor pollutants and the inability of current combustion models to predict the formation of minor products such as alkenes, dienes, aromatics, aldehydes and soot nano-particles which have a deleterious impact on both the environment and on human health. Cleaner Combustion describes, at a fundamental level, the reactive chemistry of minor pollutants within extensively validated detailed mechanisms for traditional fuels, but also innovative surrogates, describing the complex chemistry of new environmentally important bio-fuels. Divided into five sections, a broad yet detailed coverage of related research is provided. Beginning with the development of detailed kinetic mechanisms, chapters go on to explore techniques to obtain reliable experimental data, soot and polycyclic aromatic hydrocarbons, mechanism reduction and uncertainty analysis, and elementary reactions. This comprehensive coverage of current research provides a solid foundation for researchers, managers, policy makers and industry operators working in or developing this innovative and globally relevant field.
Download or read book Nano Antimicrobials written by Nicola Cioffi and published by Springer Science & Business Media. This book was released on 2012-02-26 with total page 563 pages. Available in PDF, EPUB and Kindle. Book excerpt: There is a high demand for antimicrobials for the treatment of new and emerging microbial diseases. In particular, microbes developing multidrug resistance have created a pressing need to search for a new generation of antimicrobial agents, which are effective, safe and can be used for the cure of multidrug-resistant microbial infections. Nano-antimicrobials offer effective solutions for these challenges; the details of these new technologies are presented here. The book includes chapters by an international team of experts. Chemical, physical, electrochemical, photochemical and mechanical methods of synthesis are covered. Moreover, biological synthesis using microbes, an option that is both eco-friendly and economically viable, is presented. The antimicrobial potential of different nanoparticles is also covered, bioactivity mechanisms are elaborated on, and several applications are reviewed in separate sections. Lastly, the toxicology of nano-antimicrobials is briefly assessed.
Download or read book Microbial Bioremediation Biodegradation written by Maulin P. Shah and published by Springer Nature. This book was released on 2020-04-30 with total page 547 pages. Available in PDF, EPUB and Kindle. Book excerpt: Microbial or biological degradation has long been the subject of active concern, and the rapid expansion and growing sophistication of various industries in the last century has significantly increased the volume and complexity of toxic residues of wastes. These can be remediated by plants and microbes, either natural origin or adapted for a specific purpose, in a process known as bioremediation. The interest in microbial biodegradation of pollutants has intensified in recent years in an attempt to find sustainable ways to clean contaminated environments. These bioremediation and biotransformation methods take advantage of the tremendous microbial catabolic diversity to degrade, transform or accumulate a variety of compounds, such as hydrocarbons, polychlorinated biphenyls, polaromatic hydrocarbons pharmaceutical substances, radionuclides and metals. Unlike conventional methods, bioremediation does not physically disturb the site. This book describes the basic principles of biodegradation and shows how these principles are related to bioremediation. Authored by leading, international environmental microbiologists, it discusses topics such as aerobic biodegradation, microbial degradation of pollutants, and microbial community dynamics. It provides valuable insights into how biodegration processes work and can be utilised for pollution abatement, and as such appeals to researchers and postgraduate students as well as experts in the field of bioremediation.
Download or read book Photoacoustic and Photothermal Phenomena written by Peter Hess and published by Springer. This book was released on 2014-03-12 with total page 575 pages. Available in PDF, EPUB and Kindle. Book excerpt: photoacoustic and Photothermal Phenomena contains reviews and a large numberof selected contributed papers reporting progress in the application of new photoacoustic and photo- thermal techniques in physics, chemistry, biology, medicine and materials science. Theoretical and experimental work is presented on spectroscopy, kinetics and relaxation, trace analysis, mass and heat transport, surfaces and thin films, nondestructive evaluation,ultrasonics and semiconductors.
Download or read book Traditional Herbal Medicine Research Methods written by Willow J.H. Liu and published by John Wiley & Sons. This book was released on 2011-03-29 with total page 393 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book introduces the methodology for collection and identification of herbal materials, extraction and isolation of compounds from herbs, in vitro bioassay, in vivo animal test, toxicology, and clinical trials of herbal research. To fully understand and make the best use of herbal medicines requires the close combination of chemistry, biochemistry, biology, pharmacology, and clinical science. Although there are many books about traditional medicines research, they mostly focus on either chemical or pharmacological study results of certain plants. This book, however, covers the systematic study and analysis of herbal medicines in general – including chemical isolation and identification, bioassay and mechanism study, pharmacological experiment, and quality control of the raw plant material and end products.
Download or read book Design of Advanced Photocatalytic Materials for Energy and Environmental Applications written by Juan M. Coronado and published by Springer Science & Business Media. This book was released on 2013-05-27 with total page 352 pages. Available in PDF, EPUB and Kindle. Book excerpt: Research for the development of more efficient photocatalysts has experienced an almost exponential growth since its popularization in early 1970’s. Despite the advantages of the widely used TiO2, the yield of the conversion of sun power into chemical energy that can be achieved with this material is limited prompting the research and development of a number of structural, morphological and chemical modifications of TiO2 , as well as a number of novel photocatalysts with very different composition. Design of Advanced Photocatalytic Materials for Energy and Environmental Applications provides a systematic account of the current understanding of the relationships between the physicochemical properties of the catalysts and photoactivity. The already long list of photocatalysts phases and their modifications is increasing day by day. By approaching this field from a material sciences angle, an integrated view allows readers to consider the diversity of photocatalysts globally and in connection with other technologies. Design of Advanced Photocatalytic Materials for Energy and Environmental Applications provides a valuable road-map, outlining the common principles lying behind the diversity of materials, but also delimiting the imprecise border between the contrasted results and the most speculative studies. This broad approach makes it ideal for specialist but also for engineers, researchers and students in related fields.
