DOCSLIB.ORG

2. Mass Spectrometry and Gas-Phase Ion Chemistry

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text

Load more

Universidade de Lisboa Faculdade de Ciências (Departamento de Química e Bioquímica) EXPLORING THE CHEMICAL PROPERTIES OF ELEMENTARY ACTINIDE SPECIES IN THE GAS PHASE Ana Filipa Folgado de Lucena Tese orientada por Doutor Joaquim Marçalo (C2TN-IST), Doutor John K. Gibson (LBNL) e Doutor João Paulo Leal (FCUL, C2TN-IST), Documento especialmente elaborado para a obtenção do grau de Doutor em Química, especialidade Química-Física 2015 The work presented in this thesis was performed at Grupo de Química dos Elementos-f, Centro de Ciências e Tecnologias Nucleares, Instituto Superior Técnico, Universidade de Lisboa (C2TN/IST), and also at Glenn T. Seaborg Center, Chemical Sciences Division, Lawrence Berkeley National Laboratory (LBNL) and Laboratory of Ligand-Actinide Interactions (LILA) at Comissariat à l’Energie Atomique et aux Energies Alternatives (CEA), with financial support from the Fundação para a Ciência e a Tecnologia (SFRH/BD/70475/2010). To my husband and my daughter To my mother Acknowledgments There are a great number of people that have contributed, directly or indirectly, to the completion of this thesis and without whom this journey would be much harder, if not, impossible. First of all, I would like to express my sincere gratitude to my thesis supervisors: Dr. Joaquim Marçalo, who generously suggested and invited me to go through this Ph.D., and has always motivated and supported me with his knowledge and competence. Although he is a very busy researcher, he always arranged time to explain and to make me aware of several important aspects, with a remarkable memory, sometimes better than mine! Thank you for leading me into the world of the gas-phase ion chemistry and to continuously challenging me, making me progress and grow as a scientist. Dr. John K. Gibson, for hosting me at the Lawrence Berkeley National Laboratory with enormous sympathy, for his supervision with the actinides experiments, for all the scientific discussions together with Dr. Joaquim Marçalo, and the prompt corrections and email answers. Dr. João Paulo Leal for accepting to supervise my work and being always available for any corrections and suggestions, and for being the link with the University, helping me with all the bureaucratic issues. I would also like to acknowledge the Foundation for Science and Technology (FCT) for my personal doctoral grant (SFRH/BD/70475/2010) and to Centro de Ciências e Tecnologias Nucleares, Instituto Superior Técnico, Universidade de Lisboa (C2TN/IST) for hosting and providing me the necessary conditions to develop my work. A special thanks to all the co-authors of the works described in this thesis. It would have never been possible to accomplish the reported results and conclusions if it wasn’t your important contribution. A special thanks to Dr. Maria Michelini for the theoretical computations and for such kindness and sympathy during my stay in Berkeley. To Dr. Yu Gong, for guiding me with all the actinide ESI-MS experiments at LBNL and through all the necessary procedures to work under a radiological environment, more specifically with the radiologic glove box. Also, thank you for the hints and tips about Berkeley and San Francisco, for showing me the criminal map of Oakland and for understanding that a left-handed woman doesn't bring bad luck! I want also to acknowledge the LILA Lab, at CEA France, specially Dr. Laurence Berthon and Mrs. Nicole Zorz for guiding me with the americium experiments. Also, I want to thank Mathieu Audras and Sarah Mostapha for the companionship at the office/lab and during my stay in France. I would like also to acknowledge Dr. M. Conceição Oliveira and Mrs. Ana Dias, for the collaboration and all the ESI-MS experiments performed at CQE-IST. To Grupo de Química dos Elementos-f at C2TN-IST, in particular to Dr. Leonor Maria, for the scientific discussions, for all the suggestions regarding my thesis and for motivating me during all these years; it was a pleasure to work with you. To Dr. José Carretas, who collaborated in most of the experiments of my work, showing up always in a good mood, always “moralizado”. To Adelaide Cruz, for helping me at the lab and sharing the office with me during all these years, spreading laughs and happiness everywhere. To my co-workers and friends - “as meninas” Cybelle ix Soares, Marina Soares, Joana Vitorino, Vânia Sousa, Ana Ferreira and Ana Moura, thank you for sharing all the good and bad moments of this journey, for listening and advising me. A special thanks also to the former grantholders and my dearest friends Célia Lourenço and Elsa Mora, who were present since the very beginning of this journey. To Dr. Joaquim Branco, Dr. Teresa Gasche, Dr. Maria Augusta Antunes, Dr. Bernardo Monteiro and Dr. Cláudia Pereira, for the important comments and discussions at every group meeting. To all my QA friends from the Faculdade de Ciências e Tecnologia, who directly or indirectly made my days better, specially, Catarina Custódio (a minha Pucca), Vanessa Nascimento, Ricardo Barata, Sofia Martins, Raquel Teixeira, Joana Pais, Patrique Nunes, Cristina Oliveira, Bárbara Chagas, Ricardo Melo, António Barata, Leonardo Mendes, Vitor Silva, André Costa, most of you great scientists, thank you all for the friendship, the days spent at Dona Teresa and at the Sala de convívio playing endless sueca, the nights out, all the weird geek discussions, all the laughs and the support in every moment of my life, that greatly contributed for who I am today. To my new friends in Italy, le ragazze: Suzanne, Sylvia, Kaat, Manuela, Carolina, Vera, Heidi, Amelia, Nami and Mrs. Giuliana Potts (insegnante di italiano), per le ottime pause pranzo ogni martedì. È stato sicuramente il giorno più bello della settimana! Un bacione a tutti voi! I would like to acknowledge also the ones that have always supported me in the background: my family, aos Lopes e Mendes, queridas manas Inês e Andreia, fofinhos Margarida e Miguel e Avó Alice; à minha avózinha Lia, aos meus tios Sú, Cadi e Lívia e primos AlexDaTuga e Catas. À minha querida mãe, pelo seu amor incondicional e achar que eu sou “a maior”, e, por último, um agradecimento mais que especial ao meu melhor amigo, companheiro, marido e pai, João, e à nossa bebé Filipa, vocês são a base da pirâmide – obrigada por tudo. Por último, dedico a tese em memória do meu Pai, que sempre me incentivou a progredir e que ficaria certamente orgulhoso de me ver atingir tamanha conquista. x Exploring the chemical properties of elementary actinide species in the gas phase Abstract Gas-phase ion chemistry studies were conducted to search for new elementary actinide (An) species and reactions and to enhance the fundamental understanding of these elements. In the gas phase, with the absence of external perturbations (solvents), physical and chemical properties of elementary actinide species were better studied and relationships between electronic structure, reactivity and energetics established. The role of the 5f electrons and the covalency in these heavy elements were important aspects examined. Most of the studies were performed in parallel with theoretical calculations (through international collaborations), which were essential for complementing the understanding of actinide chemistry. The studies were performed with the use of mass spectrometry techniques, namely Laser Ionization Fourier Transform Ion Cyclotron Resonance (LI-FT-ICR-MS) and Electrospray Ionization Quadrupole Ion Trap (ESI-QIT-MS). The use of these ion traps were very effective for the ion/molecule reaction studies, enabling to perform complex sequences of ion manipulation and obtaining kinetic and mechanistic information. New +/2+ actinide species and processes were identified, with the actinyl ions, AnO2 , being the highlight of the work: oxo-exchange with water and methanol; addition reactions of water and oxygen to actinyl ions, with a focus in the formation of superoxide uranyl(VI) ions from uranyl(V); synthesis of sulfur “analogues” of actinyls from reactions of An+/2+ ions with COS; determination of the effective charge density of U in uranyl(VI), comparable to that of the late trivalent lanthanides, from the dissociation of bimetallic clusters; evaluation of III/IV redox stabilities of lanthanides and - actinides by measurement of hydrolysis rates for MO(NO3)3 species; and coordination studies of biologically relevant ligands, amino acids in particular, that allowed establishing trends of relative stabilities/affinities towards the actinyl ions. Keywords Gas-phase ion chemistry, FT-ICR-MS, ESI-QIT-MS, Actinyl ions, Ion/molecule reactions, Collision-induced dissociation, 5f electrons. xi xii Estudo das propriedades químicas de espécies elementares de actinídeos em fase gasosa Resumo Foram efetuados estudos de química de iões em fase gasosa com o objetivo de obter novas espécies e reações de actinídeos (An) e ampliar o conhecimento destes elementos a nível fundamental. Devido à ausência de fatores externos na fase gasosa, nomeadamente solventes, é possível realizar estudos mais precisos das propriedades físicas e químicas de espécies com actinídeos e estabelecer relações entre reatividade, energética e estrutura eletrónica. O papel dos eletrões 5f e a covalência neste tipo de elementos foram dois aspetos importantes abordados. A parte experimental foi realizada em simultâneo com cálculos teóricos, através de colaborações internacionais, que foram essenciais uma vez que permitiram complementar o conhecimento da química dos actinídeos. Recorreu-se ao uso de técnicas de espectrometria
Recommended publications
  • Inelastic Collisions of Atomic Thorium and Molecular Thorium Monoxide with Cold Helium-3

    Inelastic Collisions of Atomic Thorium and Molecular Thorium Monoxide with Cold Helium-3

    Inelastic collisions of atomic thorium and molecular thorium monoxide with cold helium-3 The Harvard community has made this article openly available. Please share how this access benefits you. Your story matters Citation Au, Yat Shan. 2014. Inelastic collisions of atomic thorium and molecular thorium monoxide with cold helium-3. Doctoral dissertation, Harvard University. Citable link http://nrs.harvard.edu/urn-3:HUL.InstRepos:12274226 Terms of Use This article was downloaded from Harvard University’s DASH repository, and is made available under the terms and conditions applicable to Other Posted Material, as set forth at http:// nrs.harvard.edu/urn-3:HUL.InstRepos:dash.current.terms-of- use#LAA Inelastic Collisions of Atomic Thorium and Molecular Thorium Monoxide with Cold Helium-3 A dissertation presented by Yat Shan Au to The Department of Physics in partial fulfillment of the requirements for the degree of Doctor of Philosophy in the subject of Physics Harvard University Cambridge, Massachusetts November 2013 c 2013 - Yat Shan Au All rights reserved. Dissertation advisor Author Professor John Morrissey Doyle Yat Shan Au Inelastic Collisions of Atomic Thorium and Molecular Thorium Monoxide with Cold Helium-3 Abstract We measure inelastic cross sections for atomic thorium (Th) and molecular thorium monoxide (ThO) in collisions with 3He at temperatures near 1 K. We determine the 3 −17 −2 Zeeman relaxation cross section for Th ( F2) to be ∼ 2 × 10 cm at 800 mK. 3 We study electronic inelastic processes in Th ( P0) and find no quenching even after 106 collisions at 800 mK. We measure the vibrational quenching cross section for ThO (X, ν = 1) to be (7:9 ± 2:7) × 10−19 cm−2 at 800 mK.
  • Ionization, Dissociation, and the Investigation of Structure in Small Molecular Models to Develop a Broader Understanding of Gas Phase Ion Chemistry

    Ionization, Dissociation, and the Investigation of Structure in Small Molecular Models to Develop a Broader Understanding of Gas Phase Ion Chemistry

    Ionization, dissociation, and the investigation of structure in small molecular models to develop a broader understanding of gas phase ion chemistry DISSERTATION Presented in Partial Fulfillment of the Requirements for the Degree Doctor of Philosophy in the Graduate School of The Ohio State University By Matthew Bernier Graduate Program in Chemistry The Ohio State University 2014 Dissertation Committee: Professor Vicki Wysocki, Advisor Professor Terry Gustafson Professor Abraham Badu-Tawiah Copyright by Matthew Bernier 2014 Abstract This dissertation focuses on molecular systems in the low-mass range to determine how chemical and structural changes can affect subsequent fragmentation chemistry and protonation site. Each system was investigated using MS analysis and gas-phase ion structural techniques selected from tandem MS (MSMS), hydrogen-deuterium exchange (HDX), ion-mobility (IM), and action infra-red multi-photon dissociation (IRMPD). In Chapter 3, the non-standard amino acid gamma-aminobutyric acid (GABA) was placed into a peptide system to test a mechanism which explained the lack of a3 ions in standard peptide fragmentations. GABA extends the peptide backbone by two methylene units and its insertion into the second position of larger peptides increases the intensity of a3 ion. Using MSMS, it was found that this was a result of blocking common favorable fragmentation pathways. The results demonstrated the use of modified peptides for revealing reasons for how peptides fragment. Chapter 4 focused on a unique set of non-canonical amino acids and their ability to affect the trans/cis nature of adjacent amide bonds in peptide sequences. In solution, 4- R-Flouroproline (R-Flp) is found to favor the trans peptide bond and 4-S-fluoroproline (S- flp) favors the cis bond.
  • Drugs and Acid Dissociation Constants Ionisation of Drug Molecules Most Drugs Ionise in Aqueous Solution.1 They Are Weak Acids Or Weak Bases

    Drugs and Acid Dissociation Constants Ionisation of Drug Molecules Most Drugs Ionise in Aqueous Solution.1 They Are Weak Acids Or Weak Bases

    Drugs and acid dissociation constants Ionisation of drug molecules Most drugs ionise in aqueous solution.1 They are weak acids or weak bases. Those that are weak acids ionise in water to give acidic solutions while those that are weak bases ionise to give basic solutions. Drug molecules that are weak acids Drug molecules that are weak bases where, HA = acid (the drug molecule) where, B = base (the drug molecule) H2O = base H2O = acid A− = conjugate base (the drug anion) OH− = conjugate base (the drug anion) + + H3O = conjugate acid BH = conjugate acid Acid dissociation constant, Ka For a drug molecule that is a weak acid The equilibrium constant for this ionisation is given by the equation + − where [H3O ], [A ], [HA] and [H2O] are the concentrations at equilibrium. In a dilute solution the concentration of water is to all intents and purposes constant. So the equation is simplified to: where Ka is the acid dissociation constant for the weak acid + + Also, H3O is often written simply as H and the equation for Ka is usually written as: Values for Ka are extremely small and, therefore, pKa values are given (similar to the reason pH is used rather than [H+]. The relationship between pKa and pH is given by the Henderson–Hasselbalch equation: or This relationship is important when determining pKa values from pH measurements. Base dissociation constant, Kb For a drug molecule that is a weak base: 1 Ionisation of drug molecules. 1 Following the same logic as for deriving Ka, base dissociation constant, Kb, is given by: and Ionisation of water Water ionises very slightly.
  • Basis for Listing Hazardous Waste

    Basis for Listing Hazardous Waste

    NEBRASKA ADMINISTRATIVE CODE Title 128 - Department of Environmental Quality Appendix II - BASIS FOR LISTING HAZARDOUS WASTE EPA Hazardous Hazardous Constituents For Which Listed Waste No. F001 Tetrachloroethylene; methylene chloride; trichloroethylene; 1,1,1-trichloroethane; carbon tetrachloride; chlorinated fluorocarbons. F002 Tetrachloroethylene; methylene chloride; trichloroethylene; 1,1,1-trichloroethane; 1,1,2-trichloroethane; chlorobenzene; 1,1,2-trichloro-1,2,2-trichfluoroethane; ortho- dichlorobenzene; trichlorofluoromethane. F003 N.A. F004 Cresols and cresylic acid, nitrobenzene. F005 Toluene, methyl ethyl ketone, carbon disulfide, isobutanol, pyridine, 2-ethoxyethanol, benzene, 2-nitropropane. F006 Cadmium, hexavalent chromium, nickel, cyanide (complexed). F007 Cyanide (salts). F008 Cyanide (salts). F009 Cyanide (salts). F010 Cyanide (salts). F011 Cyanide (salts). F012 Cyanide (complexed). F019 Hexavalent chromium, cyanide (complexed). F020 Tetra- and pentachlorodibenzo-p-dioxins; tetra- and pentachlorodibenzofurans; tri- and tetrachlorophenols and their chlorophenoxy derivative acids, esters, ethers, amine and other salts. Effective Date: 01/03/07 II-1 Title 128 Appendix II EPA Hazardous Hazardous Constituents For Which Listed Waste No. F021 Penta- and hexachlorodibenzo-p-dioxins; penta- and hexachlorodibenzofurans; pentachlorophenol and its derivatives. F022 Tetra-, penta-, and hexachlorodibenzo-p-dioxins; tetra-, penta-, and hexachlorodibenzofurans. F023 Tetra-, and pentachlorodibenzo-p-dioxins; tetra- and pentachlorodibenzofurans;
  • Radical-Radical Reactions, Pyrene Nucleation, and Incipient Soot

    Radical-Radical Reactions, Pyrene Nucleation, and Incipient Soot

    Available online at www.sciencedirect.com Proceedings of the Combustion Institute 36 (2017) 799–806 www.elsevier.com/locate/proci Radical–radical reactions, pyrene nucleation, and incipient soot formation in combustion a b b K. Olof Johansson , Tyler Dillstrom , Paolo Elvati , a a c ,d Matthew F. Campbell , Paul E. Schrader , Denisia M. Popolan-Vaida , c c b ,e Nicole K. Richards-Henderson , Kevin R. Wilson , Angela Violi , a , ∗ Hope A. Michelsen a Combustion Research Facility, Sandia National Laboratories, P. O. Box 969, MS 9055, Livermore, CA 94551, USA b Department of Mechanical Engineering, University of Michigan, Ann Arbor, MI 48109, USA c Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA d Department of Chemistry, University of California, Berkeley, CA 94720, USA e Departments of Chemical Engineering, Biomedical Engineering, Macromolecular Science and Engineering, Biophysics Program, University of Michigan, Ann Arbor, MI 48109, USA Received 3 December 2015; accepted 31 July 2016 Available online 12 October 2016 Abstract We present a combined experimental and probabilistic simulation study of soot-precursor. The experi- ments were conducted using aerosol mass spectrometry coupled with tunable vacuum ultraviolet radiation from the Advanced Light Source at Lawrence Berkeley National Laboratory. Mass spectra and photoion- ization efficiency (PIE) curves of soot precursor species were measured at different heights in a premixed flat flame and in a counter-flow diffusion flame fueled by ethylene and oxygen. The PIE curves at the pyrene mass from these flames were compared with reference PIE scans recorded for pyrene. The results demonstrate that other C 16 H 10 isomers than pyrene are major components among species condensed onto incipient soot in this study, which is in agreement with the simulations.
  • Extraction of Thorium Oxide from Monazite Ore

    Extraction of Thorium Oxide from Monazite Ore

    University of Tennessee, Knoxville TRACE: Tennessee Research and Creative Exchange Supervised Undergraduate Student Research Chancellor’s Honors Program Projects and Creative Work 5-2019 Extraction of Thorium Oxide from Monazite Ore Makalee Ruch University of Tennessee, Knoxville, [email protected] Chloe Frame University of Tennessee, Knoxville Molly Landon University of Tennessee, Knoxville Ralph Laurel University of Tennessee, Knoxville Annabelle Large University of Tennessee, Knoxville Follow this and additional works at: https://trace.tennessee.edu/utk_chanhonoproj Part of the Environmental Chemistry Commons, Geological Engineering Commons, and the Other Chemical Engineering Commons Recommended Citation Ruch, Makalee; Frame, Chloe; Landon, Molly; Laurel, Ralph; and Large, Annabelle, "Extraction of Thorium Oxide from Monazite Ore" (2019). Chancellor’s Honors Program Projects. https://trace.tennessee.edu/utk_chanhonoproj/2294 This Dissertation/Thesis is brought to you for free and open access by the Supervised Undergraduate Student Research and Creative Work at TRACE: Tennessee Research and Creative Exchange. It has been accepted for inclusion in Chancellor’s Honors Program Projects by an authorized administrator of TRACE: Tennessee Research and Creative Exchange. For more information, please contact [email protected]. Extraction of Thorium Oxide from Monazite Ore Dr. Robert Counce Department of Chemical and Biomolecular Engineering University of Tennessee Chloe Frame Molly Landon Annabel Large Ralph Laurel Makalee Ruch CBE 488: Honors
  • Actinide Arene-Metalates: Ion Pairing Effects on the Electronic Structure of Unsupported Uranium- Arene Sandwich Complexes

    Actinide Arene-Metalates: Ion Pairing Effects on the Electronic Structure of Unsupported Uranium- Arene Sandwich Complexes

    Actinide Arene-Metalates: Ion Pairing Effects on the Electronic Structure of Unsupported Uranium- Arene Sandwich Complexes Jesse Murillo,† Rina Bhowmick,‡ Katie L. M. Harriman,ǁ Alejandra Gomez-Torres,† Joshua Wright,¥ Robert W. Meulenberg,± Pere Miró,‡ Alejandro Metta-Magaña,† Muralee Murugesu,ǁ Bess Vlaisavljevich,*,‡ and Skye Fortier*,† †Department of Chemistry and Biochemistry, University of Texas at El Paso, El Paso, Texas 79968, United States ‡Department of Chemistry, University of South Dakota, Vermillion, South Dakota 57069, United States ǁDepartment of Chemistry and Biomolecular Sciences, University of Ottawa, Ottawa, Ontario K1N 6N5, Canada ¥ Department of Physics, Illinois Institute of Technology, Chicago, IL, 60616, United States ± Department of Physics and Astronomy and Frontier Institute for Research in Sensor Technologies, University of Maine, Orono, ME, 04469, United States ABSTRACT: Chatt reaction methods were employed to synthesize the first well characterized actinide-arene sand- wich complexes. Namely, addition of [UI2(THF)3(μ-OMe)]2⸱THF (2⸱THF) to THF solutions containing 6 equiv. 6 4 of K[C14H10] generates the dimeric complexes [K(18-crown-6)(THF)2]2[U(η -C14H10)(η -C14H10)(μ-OMe)]2⸱4THF 18C6 6 4 THF (1 ⸱4THF) and {[K(THF)3][U(η -C14H10)(η -C14H10)(μ-OMe)]}2 (1 ) upon crystallization of the products in THF in the presence or absence of 18-crown-6, respectively. Both 118C6⸱4THF and 1THF are thermally stable in the solid-state at room temperature; however, after crystallization, they become insoluble in THF or DME solutions and instead gradually decompose upon standing. X-ray diffraction analysis reveals 118C6⸱4THF and 1THF to be structurally similar, possessing uranium centers sandwiched between anthracene ligands of mixed tetrahapto and hexahapto ligation modes.
  • Compounds † † ‡ § † Caleb J

    Compounds † † ‡ § † Caleb J

    Article Cite This: Organometallics 2019, 38, 1031−1040 pubs.acs.org/Organometallics Investigation of the Electronic Structure of Aryl-Bridged Dinuclear U(III) and U(IV) Compounds † † ‡ § † Caleb J. Tatebe, John J. Kiernicki, Robert F. Higgins, Robert J. Ward, Sean N. Natoli, † † † † ‡ James C. Langford, Christopher L. Clark, Matthias Zeller, Paul Wenthold, Matthew P. Shores, § † Justin R. Walensky, and Suzanne C. Bart*, † H. C. Brown Laboratory, Department of Chemistry, Purdue University, West Lafayette, Indiana 47907, United States ‡ Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523, United States § Department of Chemistry, University of Missouri, Columbia, Missouri 65211, United States *S Supporting Information ABSTRACT: A family of dinuclear bis(Tp*) (Tp* = hydrotris(3,5- dimethylpyrazolyl)borate) uranium compounds with conjugated organic linkers was synthesized to explore possible electronic communication between uranium ions. Trivalent diuranium phenyl alkynyl compounds, * * meta * Tp 2UCC(1,3-C6H4)CCUTp 2 (2- )orTp2UCC(1,4-C6H4)- * para CCUTp 2 (2- ), and tetravalent diuranium phenylimido compounds, * − * meta * − Tp 2U(N-1,3-C6H4 N)UTp 2 (3- )andTp2U(N-1,4-C6H4 * para * N)UTp 2 (3- ), were generated from trivalent Tp 2UCH2Ph. All compounds were fully characterized both spectroscopically and structurally. The electronic structures of all derivatives were interrogated using magnetic measurements, electrochemistry, and were the subject of computational analyses. All of these data combined established
  • Gas-Phase Ion Chemistry: Kinetics and Thermodynamics

    Gas-Phase Ion Chemistry: Kinetics and Thermodynamics

    Gas-Phase Ion Chemistry: Kinetics and Thermodynamics by Charles M. Nichols B. S., Chemistry – ACS Certified University of Central Arkansas, 2009 A thesis submitted to the Faculty of the Graduate School of the University of Colorado in partial fulfillment of the requirements for the degree of Doctor of Philosophy Department of Chemistry and Biochemistry 2016 This thesis entitled: Gas-Phase Ion Chemistry: Kinetics and Thermodynamics Written by Charles M. Nichols has been approved for the Department of Chemistry and Biochemistry by: _______________________________________ Veronica M. Bierbaum _______________________________________ W. Carl Lineberger Date: December 08, 2015 A final copy of this thesis has been examined by all signatories, and we find that both the content and the form meet acceptable presentation standards of scholarly work in the above mentioned discipline. Nichols, Charles M. (Ph.D., Physical Chemistry) Gas Phase Ion Chemistry: Kinetics and Thermodynamics Thesis directed by Professors Veronica M. Bierbaum and W. Carl Lineberger Abstract: This thesis employs gas-phase ion chemistry to study the kinetics and thermodynamics of chemical reactions and molecular properties. Gas-phase ion chemistry is important in diverse regions of the universe. It is directly relevant to the chemistry occurring in the atmospheres of planets and moons as well as the molecular clouds of the interstellar medium. Gas-phase ion chemistry is also employed to determine fundamental properties, such as the proton and electron affinities of molecules. Furthermore, gas-phase ion chemistry can be used to study chemical events that typically occur in the condensed-phase, such as prototypical organic reactions, in an effort to reveal the intrinsic properties and mechanisms of chemical reactions.
  • Arrhenius Theory of Dissociation • Dissociation Happens Spontaneously When Ionic (Soluble) Compounds Dissolve in H2O

    Arrhenius Theory of Dissociation • Dissociation Happens Spontaneously When Ionic (Soluble) Compounds Dissolve in H2O

    Arrhenius Theory of Dissociation • Dissociation happens spontaneously when ionic (soluble) compounds dissolve in H2O. • The more ions are present (i.e. the better it dissociates), the more electricity is conducted. http://antoine.frostburg.edu/chem/senese/101/reactions/slides/sld006.htm Classification of electrolytes • Strong – soluble ionic substances (salts), mineral acids, bases – Acids: HCl, HBr, HI, HNO3, H2SO4, HClO4 – Bases: LiOH, NaOH, KOH, RbOH, CsOH, Ca(OH)2, Sr(OH)2, Ba(OH)2 • Weak – carboxylic acids, amines • Non-electrolytes – most organic compounds • The words “strong” and “weak” refer only to how well something dissociates and forms ions, NOT if it is dangerous, reactive, etc. Determining concentrations of ionic solutions • For the [ ] of ions, we need to consider both the formula and whether or not it dissociates completely (strong electrolyte) What is stoichiometry? • (Probably) the most important topic in chemistry! • This is the basis for many subsequent chapters • Related to the amount of a species or substance • Sometimes referred to as the mathematics of chemistry Some definitions • Molar mass (aka molecular weight) – sum of atomic masses (weights) for all the atoms in a given molecule. – Use the periodic table and the molecular formula to determine this • Formula mass (formula weight) – sum of the masses for all the ions in a given formula unit The periodic table An Important Interpretation • The stoichiometric coefficients that are present in a balanced chemical reaction are related to the ratios of reactants and products in a chemical reaction • This ratio is only in terms of moles (or molecules), BUT NOT mass! Example • The final step in the production of nitric acid involves the reaction of nitrogen dioxide with water; nitrogen monoxide is also produced.
  • Suppression of the Optical Crosstalk in a Multi-Channel Silicon Photomultiplier Array

    Suppression of the Optical Crosstalk in a Multi-Channel Silicon Photomultiplier Array

    Suppression of the optical crosstalk in a multi-channel silicon photomultiplier array Takahiko Masuda1, Daniel G. Ang2, Nicholas R. Hutzler3, Cole Meisenhelder2, Noboru Sasao1, Satoshi Uetake1, Xing Wu2,4, David DeMille4, Gerald Gabrielse5, John M. Doyle1,2, and Koji Yoshimura1 1Research Institute for Interdisciplinary Science, Okayama University, Okayama 700-8530, Japan 2Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA 3Division of Physics, Mathematics, and Astronomy, California Institute of Technology, Pasadena, California 91125, USA 4James Franck Institute and Department of Physics, University of Chicago, Chicago, Illinois 60637, USA 5Center for Fundamental Physics, Northwestern University, Evanston, Illinois 60208, USA May 5, 2021 Abstract We propose and study a method of optical crosstalk suppression for silicon photomultipliers (SiPMs) using optical filters. We demonstrate that attaching absorptive visible bandpass filters to the SiPM can substantially reduce the optical crosstalk. Measurements suggest that the absorption of near infrared light is important to achieve this suppression. The proposed technique can be easily applied to suppress the optical crosstalk in SiPMs in cases where filtering near infrared light is compatible with the application. 1 Introduction A silicon photomultiplier (SiPM) consists of an array of small avalanche photodiode pixels that are built on a silicon substrate. These pixels are operated in Geiger Mode and are sensitive to arXiv:2105.01519v1 [physics.ins-det] 4 May 2021 single photon injection, where a single photon stimulates an avalanche process in a single pixel that discharges the pixel completely. All pixels are electrically connected in parallel, so the output signal is an analog pulse whose charge is proportional to the total number of fired pixels.
  • Na2co3(S) → 2 Na (Aq) +

    Na2co3(S) → 2 Na (Aq) +

    Bellevue College CHEM& 121 Experiment: Ionic Solutions (Electrolyte Solutions)* Introduction Molecular compounds are made up of molecules, while ionic compounds are made up of ions. Ions are different from molecules, as they have a charge. In an ionic compound, the number of positively charged cations and negatively charged anions are such that charges are balanced. For example, in the diagram below, note that there are two sodium cations (+1) to balance the charge of each carbonate anion (-2). Many ionic compounds dissolve in water; many do not. If an ionic compound dissolves in water, it separates into individual charged ions. For example, when the soluble compound sodium carbonate dissolves in water, the partial negatively charged side of the polar water molecules surround the positively charged sodium ions, while the partial positively charged side of the polar water molecules surround the negatively charged carbonate ions. The resulting solution is composed of separate sodium ions and carbonate ions surrounded by water molecules. O H H H H O Na+ H Na+ O H 2– H Na+ CO H 2– O 3 O CO 3 H O H H H Na+ 2– CO Na+ 3 The following chemical equation communicates how the soluble ionic compound, sodium carbonate, separates into sodium ions, and carbonate ions. The notation “(aq)” means “aqueous” or that the ion is dissolved in water. Note that water is not written as a reactant, but over the reaction arrow. H2O + 2- Na2CO3(s) à 2 Na (aq) + CO3 (aq) Once ionic compounds are dissolved, the ions in solution may undergo further chemical reactions with other substances, including neutralization, precipitation, oxidation-reduction, and other reactions.