Download or read book A Quantitative Raman and Density Functional Theory Investigation of Uranyl Sulfate Complexation and Liquid Liquid Phase Separation Under Hydrothermal Conditions written by Christopher Darrell Alcorn and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: State-of-the-art Raman spectroscopic techniques have been employed to quantitatively measure (i) the temperature-dependent Raman properties and thermal decomposition of several non-complexing anions in acidic and neutral solutions at temperatures up to 400 oC, (ii) the first and second formation constants of the uranyl sulfate system from 25 - 375 °C, and (iii) the speciation and concentrations of liquid-liquid phase separated mixtures of uranyl sulfate and sulfuric acid up to 425 °C. The results of the first study show the stability followed the order HSO4- (stable) > ReO4- > ClO4- > CF3SO3- in acidic solution, with half-lives over 7 h at 300 oC. In neutral solutions, the order was HSO4- (stable) > CF3SO3- > ReO4- > ClO4-, with half-lives over 8 h at 350 oC. Raman vibrational frequencies and relative Raman scattering coefficients of these anions were determined, providing temperature-dependent data for frequency calibration and for determining the efficiency of these anions to scatter Raman light. To our knowledge, this manuscript is the first of its kind to report quantitative values using this methodology. The first and second formation constants of the uranyl sulfate system were quantitatively determined for the first time at t > 75 °C up to supercritical conditions. A drastic increase in both constants is observed, compared to an extrapolation of literature values, owing to the formation of uranyl sulfate complexes at high temperature. At t > 375 °C, uranyl sulfate solutions separated into two immiscible liquids, rich and deficient in uranium, respectively. A solid, presumed to be UO3·H2O(s), formed in the rich phase of solutions without excess sulfuric acid. Analysis shows the uranyl ion is completely complexed in both phases, forming UO2SO40(aq) and minor amounts of UO2(SO4)22-(aq). The relative abundance of UO2SO40(aq) increases with temperature. At t ≥ 400 °C, excess HSO4-(aq) forms in the uranium rich phase. For the uranium deficient phase, no uranium or sulfur species are detectable at 400 °C. Concentrations in both phases were quantified by using the homogeneous phase spectra as an external standard, together with densities calculated using the Helgeson-Kirkham-Flowers equation of state, and a reasonable density estimation using apparent molar volumes.
Download or read book Time Resolved Resonance Raman and Density Functional Theory Investigation of the T1 Triplet States and Radical Cations of Substituted Biphenyl Compounds written by 李昌運 and published by Open Dissertation Press. This book was released on 2017-01-27 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation, "Time-resolved Resonance Raman and Density Functional Theory Investigation of the T1 Triplet States and Radical Cations of Substituted Biphenyl Compounds" by 李昌運, Cheong-wan, Lee, was obtained from The University of Hong Kong (Pokfulam, Hong Kong) and is being sold pursuant to Creative Commons: Attribution 3.0 Hong Kong License. The content of this dissertation has not been altered in any way. We have altered the formatting in order to facilitate the ease of printing and reading of the dissertation. All rights not granted by the above license are retained by the author. DOI: 10.5353/th_b3122462 Subjects: Radicals (Chemistry) Triplet state Biphenyl compounds - Spectra Cations Raman spectroscopy Density functionals
Download or read book The System Uranyl Sulfate water written by C. H. Secoy and published by . This book was released on 1949 with total page 10 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Time Resolved Resonance Raman and Density Functional Theory Investigations of Selected Isopolyhalomethanes Haloalkyl Radicals and Polyhalomethane Halogen Atom Molecular Complexes and Their Reactions written by Yunliang Li and published by . This book was released on 2017-01-27 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation, "Time-resolved resonance Raman and density functional theory investigations of selected isopolyhalomethanes, haloalkyl radicals and polyhalomethane/halogen atom molecular complexes and their reactions" by Yunliang, Li, 李運良, was obtained from The University of Hong Kong (Pokfulam, Hong Kong) and is being sold pursuant to Creative Commons: Attribution 3.0 Hong Kong License. The content of this dissertation has not been altered in any way. We have altered the formatting in order to facilitate the ease of printing and reading of the dissertation. All rights not granted by the above license are retained by the author. DOI: 10.5353/th_b3124571 Subjects: Raman effect, Resonance Density functionals Methane Halogen compounds
Download or read book The System Uranyl Sulfate water written by C. H. Secoy and published by . This book was released on 1948 with total page 8 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Raman Investigation of Nickel Chloride Complexation Under Hydrothermal Conditions written by Katherine Bissonette and published by . This book was released on with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Resonance Raman Time Resolved Resonance Raman and Density Functional Theory Study of Benzoin Diethyl Phosphate Selected P Hydroxy and P Methoxy Substituted Phenacyl Ester Phototrigger and Model Compounds written by Wing-Sum Chan and published by . This book was released on 2017-01-27 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation, "Resonance Raman, Time-resolved Resonance Raman and Density Functional Theory Study of Benzoin Diethyl Phosphate, Selected P-Hydroxy and P-methoxy Substituted Phenacyl Ester Phototrigger and Model Compounds" by Wing-sum, Chan, 陳穎心, was obtained from The University of Hong Kong (Pokfulam, Hong Kong) and is being sold pursuant to Creative Commons: Attribution 3.0 Hong Kong License. The content of this dissertation has not been altered in any way. We have altered the formatting in order to facilitate the ease of printing and reading of the dissertation. All rights not granted by the above license are retained by the author. Abstract: RESONANCE RAMAN, TIME-RESOLVED RESONANCE RAMAN AND DENSITY FUNCTIONAL THEORY STUDY OF BENZOIN DIETHYL PHOSPHATE, SELECTED P-HYDROXY AND P-METHOXY SUBSTITUTED PHENACYL ESTER PHOTOTRIGGER AND MODEL COMPOUNDS Submitted by Wing Sum CHAN for the degree of Doctor of Philosophy at The University of Hong Kong in August 2005 Resonance Raman (RR) spectroscopy and density functional theory (DFT) calculations were done to characterize the structure and dynamics of selected phototrigger and model compounds. Nanosecond time-resolved resonance Raman (ns-TR ) spectra of p-hydroxyphenacyl diethyl phosphate (HPDP), 4-methxoyphenacyl diethyl phosphate (MPDP) and its model compound 4''-methoxyacetophenone (MPA) in acetonitrile and in the water/acetonitrile mixed solvents are reported. The results from the DFT calculations and the ns-TR spectra indicate hydrogen-bonding leads to substantial modification of both the electronic properties and structural conformation of the triplet state MAP molecule. The free triplet MAP molecule was found to have a slightly twisted geometry with a delocalized ππ* character whereas the H-bonded MAP complex has a planar geometry with a significant ring localized biradical ππ nature. A strong solvent effect on the triplet quenching dynamics was observed for the HPDP molecule. This in conjunction with the leaving group dependence of the triplet decay observed in HPDP and related molecules are consistent with a solvent assisted triplet heterolytic cleavage pathway for the HPDP photodeprotection reaction. Intermolecular hydrogen-bonding of the HPDP molecule with the solvent water molecules appears to be essential to drive its cleavage or deprotection reaction. A spiroketone intermediate was proposed to be an intermediate after the deprotection reaction of HPDP and before the rearrangement process that results in the formation of the p-hydroxyphenylacetic acid (HPAA) final product. The results reported here provide important kinetics and structural data for the photodeprotection reactions of p-hydroxy and p-methoxy phenacyl ester phototriggers. This new data provides an improved understanding of the reaction mechanism occurring after photolysis of HPDP and related phototrigger compounds in various solvents. The RR spectra of benzoin diethyl phosphate (BDP) were obtained in acetonitrile solvent with excitation to its nπ* and ππ* excited states. DFT calculations were done to determine the structure and vibrational frequencies for the ground state and the excitation energies and molecular orbitals for the lower excited states of the BDP molecule. The DFT results were used to assign the observed RR bands and for comparison and interpretation of the resonance enhancement of the experimental RR spectra. It was found that Raman modes exhibiting strong enhancement are mainly related to the benzoinyl moiety for both excited states. The results for BDP indicate there is only a relatively small displacement between the nπ* excited state and the ground state but a larger displacement between the ππ* state and the ground state. The absence of RR bands in the RR spectra related to the cleavage motion of the diethyl phosphate group rules out any direct photodissociation pathway for the BDP photodeprotection
Download or read book Development of Methods to Simulate Resonance Raman Spectra Employing Density Functional Theory written by John Francis Gaff and published by . This book was released on 2011 with total page 162 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Density Functional Theory Investigation of the Uranium Oxides written by Nicholas Anthony Brincat and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Density Functional Theory Investigation of the Uranium Oxides written by Nick Brincat and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Surface enhanced Raman Spectroscopy and Computational Chemistry for Phytoestrogen Research written by Ryo Sekine and published by . This book was released on 2011 with total page 424 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis examines the vibrational structures of six phytoestrogen isoflavones, namely, daidzein, genistein and their methoxy derivatives: formononetin, biochanin A, prunetin and 4',7-dimethoxygenistein, with a particular focus on surface-enhanced Raman spectroscopy (SERS). The purpose of this work is to develop a fundamental understanding of some of the structural and vibrational aspects of isoflavones, thereby providing a foundation for applications of vibrational spectroscopy in future phytoestrogen research. Following the first 3 introductory chapters on phytoestrogens, vibrational spectroscopy and experimental techniques, the results are presented over Chapters 4-7, of which, Chapters 4-6 are based on published or accepted articles. Chapter 7, based on unpublished work, applies the knowledge acquired in the earlier chapters to the interpretation of SERS on alternative substrates. Theoretical density functional theory (DFT) calculations are also extensively applied in aiding the interpretation of all spectra explored in this thesis, demonstrating the benefits of computational chemistry in studying vibrational spectroscopy.In Chapter 4, infrared and Raman spectra were applied in the characterization of the structural and vibrational properties of the isoflavones. The analysis was performed through a combined approach, incorporating DFT calculations, vibrational mode correlations between the isoflavone derivatives and also between their sub-structural motifs: phenol and anisole. This provides the necessary background for understanding SERS of the isoflavones in the ensuing chapters.In Chapter 5, investigations of the SERS of daidzein, which has two hydroxyl groups (7-OH and 4'-OH), and its 4'-methoxy derivative, formononetin, on citrate-reduced silver colloids (cit-AgC) are reported. In SERS, the nature of the interaction between the analyte and the metal surface is critical for the effective enhancement of the Raman signals. Through pH dependence and comparative SERS analysis of the two isoflavones, it was revealed that the OH groups needed to be deprotonated in order to interact with the silver surface and become SERS active. Accordingly, the deprotonated 7-OH acts as the site of interaction with cit-AgC on both daidzein and formononetin, and also through 4'-OH deprotonation on daidzein. Bands near 1482 and 1493 cm-1 are identified as characteristic of the anionic interactions with silver via the 7-OH and 4'-OH groups, respectively.The study is extended in Chapter 6 to a series of 5-hydroxyisoflavones: genistein (Figure T1), biochanin A, prunetin and 4',7-dimethoxygenistein, to reveal a similar pH dependent, anionic interaction via the 7-OH and 4'-OH groups. However, the 5-OH group was found not to be strongly SERS active. Limited solubility in the finely controlled SERS conditions and steric hindrance are suggested as possible reasons for their lack of interaction.Finally, in Chapter 7, a selection of alternative SERS substrates is examined for their effectiveness in aiding isoflavone analysis. Three substrates were selected on the basis of commercial availability and partial reusability: sol-gel SERS substrates, oblique angle deposition (OAD) SERS substrates and Klarite® SERS Detection substrates. Different substrates can have distinct surface environments, which can consequently affect the analyte-metal interactions and the resultant SERS profile. On sol-gel and OAD substrates, which contain silver as the SERS active surface, the isoflavones were found to undergo similar interactions as on cit-AgC, as evidenced by similarities in the measured spectra and, in particular, a number of marker bands. In contrast, the isoflavones were found to adsorb in the neutral form on the gold surface of Klarite, being weakly physisorbed via 7-OH and [pi]-cloud of the chromone group. On all three substrates, the analysis is facilitated by the fundamental understanding acquired in the earlier chapters, thereby demonstrating the applicability of the vibrational characterisations in this work on alternative substrates, and in effect, different environments.
Download or read book Hydrothermal Vents and Processes written by Lindsay Murray Parson and published by Geological Society Publishing House. This book was released on 1995 with total page 430 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Chemical Thermodynamics of Neptunium and Plutonium written by Robert J. Lemire and published by Elsevier. This book was released on 2001-08-26 with total page 876 pages. Available in PDF, EPUB and Kindle. Book excerpt: Unlike earlier books in this series, this review describes the selection of chemical thermodynamic data for species of two elements, neptunium and plutonium. Although this came about more by circumstance than design, it has allowed for a more consistent approach to chemical interpretation than might have occurred in two separate treatments. It has also drawn attention to cases where the available data do not show expected parallels, and where further work may be useful to confirm or refute apparent differences in the behaviour of neptunium and plutonium.
Download or read book Stable Isotope Geochemistry written by Jochen Hoefs and published by Springer Science & Business Media. This book was released on 2013-04-17 with total page 333 pages. Available in PDF, EPUB and Kindle. Book excerpt: Stable Isotope Geochemistry is an introduction to the use of stable isotopes in the fields of geoscience. It is subdivided into three parts: - theoretical and experimental principles; - fractionation mechanisms of light elements; - the natural variations of geologically important reservoirs. In this updated 4th edition many of the chapters have been expanded, especially those on techniques and environmental aspects. The main focus is on recent results and new developments. For students and scientists alike the book will be a primary reference with regard to how and where stable isotopes can be used to solve geological problems.
Download or read book Activity Coefficients in Electrolyte Solutions written by Kenneth S. Pitzer and published by CRC Press. This book was released on 2018-05-04 with total page 552 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book was first published in 1991. It considers the concepts and theories relating to mostly aqueous systems of activity coefficients.
Download or read book Liquid Biphasic System written by Pau Loke Show and published by Elsevier. This book was released on 2020-11-28 with total page 330 pages. Available in PDF, EPUB and Kindle. Book excerpt: Downstream bioprocesses have a significant role to play in the creation of a sustainable bio-based economy, enabling the creation of new products and systems from the more sustainable bioprocessing of natural products. Liquid Biphasic System: Fundamentals, Methods, and Applications in Bioseparation Technology explores in detail the fundamental processes and applications of this new separation system, aiding understanding of the basic principles of the technique and offering constructive criticisms on the latest findings. Including coverage of the background, principles, mechanisms, and applications, Liquid Biphasic System addresses how to adapt the technology for the purification of useful compounds with greater cost efficiency and greener processing. It is essential reading for bioprocess engineers, biochemical engineers, biosystem engineers, chemists and microbiologists working in the fields of bioprocessing. Researchers, scientists, and engineers concerned with the selection and evaluation of alternative bioseparation processes will find the book particularly useful. Provides information and examples of advanced separations in a single source Includes detailed descriptions of novel bioseparation systems Covers the latest technologies related to advanced liquid–liquid separation and their applications in various industries
Download or read book Experimental and Theoretical Approaches to Actinide Chemistry written by John K. Gibson and published by John Wiley & Sons. This book was released on 2018-03-19 with total page 534 pages. Available in PDF, EPUB and Kindle. Book excerpt: A review of contemporary actinide research that focuses on new advances in experiment and theory, and the interplay between these two realms Experimental and Theoretical Approaches to Actinide Chemistry offers a comprehensive review of the key aspects of actinide research. Written by noted experts in the field, the text includes information on new advances in experiment and theory and reveals the interplay between these two realms. The authors offer a multidisciplinary and multimodal approach to the nature of actinide chemistry, and explore the interplay between multiple experiments and theory, as well as between basic and applied actinide chemistry. The text covers the basic science used in contemporary studies of the actinide systems, from basic synthesis to state-of-the-art spectroscopic and computational techniques. The authors provide contemporary overviews of each topic area presented and describe the current and anticipated experimental approaches for the field, as well as the current and future computational chemistry and materials techniques. In addition, the authors explore the combination of experiment and theory. This important resource: Provides an essential resource the reviews the key aspects of contemporary actinide research Includes information on new advances in experiment and theory, and the interplay between the two Covers the basic science used in contemporary studies of the actinide systems, from basic synthesis to state-of-the-art spectroscopic and computational techniques Focuses on the interplay between multiple experiments and theory, as well as between basic and applied actinide chemistry Written for academics, students, professionals and researchers, this vital text contains a thorough review of the key aspects of actinide research and explores the most recent advances in experiment and theory.
