Download or read book Experimental Study of Oxygen Isotopic Fractionation in the Oxidation of Silicon Monoxide written by Qingwei Dong and published by . This book was released on 1993 with total page 390 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Oxygen Isotope Fractionation in the Vacuum Ultraviolet Photodissociation of Carbon Monoxide written by and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Several absorption bands exist in the VUV region of Carbon monoxide (CO). Emission spectra indicate that these bands are all predissociative. An experimental investigation of CO photodissociation by vacuum ultraviolet photons (90 to 108 nm; 1̃3 to 11 eV) from the Advanced Light Source Synchrotron and direct measurement of the associated oxygen isotopic composition of the products are presented here. A wavelength dependency of the oxygen isotopic composition in the photodissociation product was observed. Slope values (?'18O/?'17O) ranging from 0.76 to 1.32 were observed in oxygen three-isotope space (?'18O vs.?'17O) which correlated with increasing synchrotron photon energy, and indicate a dependency of the upper electronic state specific dissociation dynamics (e.g., perturbation and coupling associated with a particular state). An unprecedented magnitude in isotope separation was observed for photodissociation at the 105 and 107 nm synchrotron bands and are found to be associated with accidental predissociation of the vibrational states (? = 0 and 1) of the upper electronic state E1?. For each synchrotron band, a large (few hundred per mil) extent of isotopic fractionation was observed and the range of fractionation is a combination of column density and exposure time. A significant temperature dependency in oxygen isotopic fractionation was observed, indicating a rotational level dependency in the predissociation process.
Download or read book Experimental Studies of Oxygen Isotope Fractionation in the Carbonic Acid System at 15 25 and 40 C written by William Cory Beck and published by . This book was released on 2004 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: In light of recent studies that show oxygen isotope fractionation in carbonate minerals to be a function of HCO3 and CO32- concentrations, the oxygen isotope fractionation and exchange between water and components of the carbonic acid system (HCO3-, CO3 2-, and CO2(aq)) were investigated at 15°, 25°, and 40°C. To investigate oxygen isotope exchange between HCO3-, CO3 2-, and H2O, NaHCO3 solutions were prepared and the pH was adjusted over a range of 2 to 12 by the addition of small amounts of HCl or NaOH. After thermal, chemical, and isotopic equilibrium was attained, BaCl2 was added to the NaHCO3 solutions. This resulted in immediate BaCO3 precipitation; thus, recording the isotopic composition of the dissolved inorganic carbon. Data from experiments at 15°, 25°, and 40°C (1 atm) show that the oxygen isotope fractionation between HCO3- and H2O as a function of temperature is governed by the equation:1000 ;HCO3--H2O = 2.66 + 0.05(106T-2) + 1.18 + 0.52.where is the fractionation factor and T is in kelvins. The temperature dependence of oxygen isotope fractionation between CO32- and H2O is 1000 CO32--H2O = 2.28 + 0.03(106T-2) - 1.50 + 0.29. The oxygen isotope fractionation between CO2(aq) and H2O was investigated by acid stripping CO2(aq) from low pH solutions; these data yield the following equation:1000 CO2(aq)-H2O = 2.52 + 0.03(106T-2) + 12.12 + 0.33. The kinetics of oxygen isotope exchange were also investigated. The half-times for exchange between HCO3- and H2O were 3.6, 1.4, and 0.25 h at 15°, 25°, and 40°C, respectively. The half-times for exchange between CO2 and H2O were 1200, 170, and 41 h at 15, 25, and 40 (degrees) C, respectively. These results show that the 18O of the total dissolved inorganic carbon species can vary as much as 17% at a constant temperature. This could result in temperature independent variations in the 18O of precipitated carbonate minerals, especially in systems that are not chemically buffered.
Download or read book The Production and Characterisation of High Purity Ozone and Experimental and Modelling Studies of Anomalous Oxygen Isotope Effects in the Formation of Carbon Dioxide from Irradiated Mixtures of Carbon Monoxide and Ozone Or Oxygen written by Daniela Simone and published by . This book was released on 2014 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The ozone formation reaction O+O2+M→O3+M is a unique example of a chemical reaction that leads to an anomalous isotopic composition of the products, most likely due to symmetry - breaking effects. So far, results on other chemical systems that might show similar effects are spurious, even though such claims concerning reactions other than the formation of ozone have been made repeatedly.This applies in particular to the spin forbidden O+CO+M→CO2+M reaction, where two studies report a mass-independent fractionation of about 8%. Nevertheless, the presence of ozone in these experiments raises questions as to the validity of this assertion. We thus make a new attempt to study the O+CO+M reaction in the photoreactor at CCAR (University of Copenhagen) where reagents and contaminants are monitored on-line by FTIR spectroscopy. This study combined with the analysis of the spectral distribution of the employed lamps and isotope kinetic modeling lead to a complete re-interpretation of previous experiments. We conclude that available measurements are more compatible with the hypothesis that there is no mass-independent isotope fractionation in the O+CO reaction. We propose that all observations can be completely explained by an isotope transfer from ozone, involving photolytic production of O(1D) that in turn leads to OH radicals, which then rapidly form CO2 from reaction with CO. We also present a method to produce pure ozone samples and derive an upper limit on nitrogen oxide contaminations based on mass spectrometer measurements. These values will serve as benchmarks values for future studies of ozone absorption cross sections in the IR and UV.
Download or read book Dissertation Abstracts International written by and published by . This book was released on 1994 with total page 758 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Experimental Calibration of Silicon and Oxygen Isotope Fractionations Between Quartz and Water at 250 C by in Situ Microanalysis of Experimental Products and Application to Zoned Low delta 30Si Quartz Overgrowths written by and published by . This book was released on 2015 with total page 16 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Oxygen and Hydrogen Isotopic Fractionation Factors Determined in Experimental Clay water Systems written by Jean Bryna Kulla and published by . This book was released on 1984 with total page 120 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Oxygen Isotope Fractionation Studies in Mineral Systems written by James R. O'Neil and published by . This book was released on 1963 with total page 208 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Mass Independent Isotopic Fractionation in Solid Phase written by Xianping Xu and published by . This book was released on 1998 with total page 334 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Fundamental Aspects of Silicon Oxidation written by Yves J. Chabal and published by Springer. This book was released on 2012-10-05 with total page 262 pages. Available in PDF, EPUB and Kindle. Book excerpt: Discusses silicon oxidation in a tutorial fashion from both experimental and theoretical viewpoints. The authors report on the state of the art both at Lucent Technology and in academic research. The book will appeal to researchers and advanced students.
Download or read book Experimental Determination of Oxygen Isotopic Fractionation Between Water Hydrous Silicate Melts written by Don Landis Shettel and published by . This book was released on 1978 with total page 232 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Isotope Geochemistry written by William M. White and published by John Wiley & Sons. This book was released on 2015-01-27 with total page 502 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book provides a comprehensive introduction to radiogenic and stable isotope geochemistry. Beginning with a brief overview of nuclear physics and nuclear origins, it then reviews radioactive decay schemes and their use in geochronology. A following chapter covers the closely related techniques such as fission-track and carbon-14 dating. Subsequent chapters cover nucleosynthetic anomalies in meteorites and early solar system chronology and the use of radiogenic isotopes in understanding the evolution of the Earth’s mantle, crust, and oceans. Attention then turns to stable isotopes and after reviewing the basic principles involved, the book explores their use in topics as diverse as mantle evolution, archeology and paleontology, ore formation, and, particularly, paleoclimatology. A following chapter explores recent developments including unconventional stable isotopes, mass-independent fractionation, and isotopic ‘clumping’. The final chapter reviews the isotopic variation in the noble gases, which result from both radioactive decay and chemical fractionations.
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1995 with total page 456 pages. Available in PDF, EPUB and Kindle. Book excerpt: Lists citations with abstracts for aerospace related reports obtained from world wide sources and announces documents that have recently been entered into the NASA Scientific and Technical Information Database.
Download or read book 18O Isotopic Tracer Studies of Silicon Oxidation in Dry Oxygen written by Chien-Jih Han and published by . This book was released on 1986 with total page 200 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Oxygen Isotopic Fractionation in CO2 laser Microprobes written by Timothy Whipple Johnson and published by . This book was released on 2001 with total page 214 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Kinetic Study of Non mass dependent Oxygen Isotope Effects in Gas Phase Reactions and Applications for Nature written by Junshan Wen and published by . This book was released on 1991 with total page 512 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Stable Isotope Geochemistry written by John W. Valley and published by Walter de Gruyter GmbH & Co KG. This book was released on 2018-12-17 with total page 676 pages. Available in PDF, EPUB and Kindle. Book excerpt: Volume 43 of Reviews in Mineralogy and Geochemistry follows the 1986 Reviews in Mineralogy (Vol. 16) in approach but reflects significant changes in the field of Stable Isotope Geochemistry. In terms of new technology, new sub-disciplines, and numbers of researchers, the field has changed more in the past decade than in any other since that of its birth. Unlike the 1986 volume, which was restricted to high temperature fields, this book covers a wider range of disciplines. However, it would not be possible to fit a comprehensive review into a single volume. Our goal is to provide state-of-the-art reviews in chosen subjects that have emerged or advanced greatly since 1986. This volume was prepared for Short Course on Stable Isotope Geochemistry presented November 2-4, 2001 in conjunction with the annual meetings of the Geological Society of America in Boston, Massachusetts.
