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Dissertations / Theses on the topic 'Chemistry, Analytic'

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Published: 4 June 2021

Last updated: 1 August 2024

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1

Mampa, Richard Mokome. "X-ray and NMR spectropscopic studies of selected heterocyclic compounds of phosphorus and nitrogen /." Pretoria : [s.n.], 2000. http://upetd.up.ac.za/thesis/available/etd-02092006-155713/.

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2

Simandiras, Emmanuel D. "Analytic energy derivatives." Thesis, University of Cambridge, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.257217.

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3

Veltkamp, David James. "Energy dependent ion scattering spectroscopy : a chemometric study of its analytical utility /." Thesis, Connect to this title online; UW restricted, 1986. http://hdl.handle.net/1773/8584.

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4

Cai, Yue. "Nondestructive multi-element analysis of colorants for forensic applications and artwork authentication." HKBU Institutional Repository, 2013. https://repository.hkbu.edu.hk/etd_ra/1528.

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5

Seasholtz, Mary Beth. "Parsimonious construction of multivariate calibration models in chemometrics /." Thesis, Connect to this title online; UW restricted, 1992. http://hdl.handle.net/1773/8705.

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6

Lorenzo, Susan Chemistry Faculty of Science UNSW. "The supramolecular chemistry of cucurbituril molecules." Awarded by:University of New South Wales. School of Chemistry, 2006. http://handle.unsw.edu.au/1959.4/26990.

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The set of molecules cucurbit[n]uril (Qn) are macrocycles composed of n glycoluril monomers linked by methylene groups. These molecules have two oxygen-ringed portals of a diameter slightly smaller than their internal cavity diameter. This thesis describes syntheses, crystallisations, crystal structure determinations, crystal packing analyses and force field calculations exploring the supramolecular chemistry of Qn molecules and their derivatives. Qn acts as a host for guest molecules and at the outset of this project no metal containing molecule had been encapsulated in a Qn molecule. One aim of this project was to prepare such complexes. This was achieved with the synthesis and characterisation of crystalline {[cis-SnCl4(H2O)2]@Q7}2(SnCl6)3(H3O)6(H2O)23. Other compounds prepared and characterised crystallographically in the course of this project are: [(Q6)(Na3(H2O)8)]2[CoCl4]4[Co(H2O)6]2[CoCl(H2O)5]2(Cl)4, (Q5@Q10)(CH3COOH)(Cl)2(H3O)2(H2O)26, (Cl@Q5)4Q6(SnCl6)8(H3O)20(H2O)24, (Q8)3(PtCl6)4(H3O)8(H2O)x, (Q8)2(PtCl6)3(H3O)6(H2O)18, (Q7)(Cr3O10)(H3O)2(H2O)x and (Q6)(SnCl6)(H3O)2(H2O)x. While the smaller Qn (n = 5?) retain their circular forms, the larger Qn (n > 8) are less rigid and distort to accommodate larger guests. After analysis of the crystal structures of these Qn compounds and those listed in the Cambridge Structural Database, the principal packing motifs of the Qn molecules were elucidated. The most common is the portal-to-side interaction in which the portal oxygen atoms of one Qn approach the hydrogen atoms around the equator of another Qn. Force-field calculations on guest@Qn complexes were conducted to determine the mechanism for the formation of these complexes. A comparison of the intermolecular interactions of phenylated systems and comparable fluorinated phenyl systems was made using both crystal packing analyses and forcefield energy calculations. Intermolecular energy parameters for these calculations were derived and validated in this work. The principal fluorinated species studied was the [B(C6F5)4]?anion. Examination of its crystal structures found that the substitution of the hydrogen atoms by fluorine atoms is influential enough to alter the predominant intramolecular conformation. It is the ???flipper?conformer, between pairs of perfluorophenyl groups, that is overwhelmingly the favoured conformation and this has a strong effect on the types of phenyl embraces that a [B(C6F5)4]?anion will form. While the parallel 4PFE, the offset parallel 4PFE and the orthogonal 4PFE are all observed the 6PFE is not.

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7

Olsson, Jeanette. "New Techniques for Chiral Separations." Doctoral thesis, Karlstad : Faculty of Technology and Science, Chemistry, Karlstads universitet, 2008. http://www.diva-portal.org/kau/abstract.xsql?dbid=1594.

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8

Alberts, Ian Lee. "Analytic derivatives using correlated wavefunctions." Thesis, University of Cambridge, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.276837.

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9

Brown, Michael Ewart. "Reactions in the solid state." Link to this resource, 2005. http://eprints.ru.ac.za/252/.

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Thesis (D.Sc. (Chemistry)) - Rhodes University, 2006.
[Appendix]. Dedication - Acknowledgements - Curriculum vitae - Biographical notes - Publication list - Introduction to my research - Commentary-books - Commentary-research papers - Conclusions.

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10

Brown, Michael Ewart. "Reactions in the solid state." Thesis, Rhodes University, 2006. http://hdl.handle.net/10962/d1015762.

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I have chosen the title for this thesis, "Reactions in the Solid State", for two reasons: Firstly, it is broad enough to cover all of my areas of research, which have been: • Effects of irradiation on solids (PhD topic) • Silver refining (while at the Chamber of Mines) • Kinetics of decomposition of solids (with Dr A.K. Galwey and various others) • Techniques of thermal analysis • Pyrotechnic delay systems (with support from AECI Explosives) • Thermal and photostability of drugs (with Prof B.D. Glass) and, secondly, it was the title of the very successful book co-authored by Drs Andrew Galwey, David Dollimore and me. A large part of my research has been involved in the writing and editing of books, so these are covered in a separate commentary, while commentary on the more than 100 papers to which I have contributed forms the main part of this compilation. It is hoped that the electronic format will enable ready access of to all aspects of my research, including electronic versions of the original papers. The reader will need a copy of Adobe Acrobat Reader to access these.

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11

Phillips, Sarah F. "A photophysical characterization on the unique properties of perylene-3,4:9,10-BIS((3,4,5(tris(octyloxy)benzohydrazide)-dicarboximide." Akron, OH : University of Akron, 2009. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=akron1249081748.

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Thesis (M.S.)--University of Akron, Dept. of Chemistry, 2009.
"August, 2009." Title from electronic thesis title page (viewed 10/14/2009) Advisor, David A. Modarelli; Faculty reader, Matthew P. Espe; Department Chair, Kim C. Calvo; Dean of the College, Chand Midha; Dean of the Graduate School, George R. Newkome. Includes bibliographical references.

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12

Payne, Timothy Howard. "Analytic theory of liquid crystalline phenomena." Thesis, University of Southampton, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.342642.

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13

Tozer, David James. "Analytic derivatives of potential energy surface." Thesis, University of Cambridge, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.338023.

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14

Ma, Shengli. "Mid-infrared and near-infrared vibrational circular dichroism new methodologies for biological and pharmaceutical applications /." Related electronic resource: Current Research at SU : database of SU dissertations, recent titles available full text, 2008. http://wwwlib.umi.com/cr/syr/main.

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15

Fleming, Cliona Mary. "Second order chemometric methods and the analysis of complex data /." Thesis, Connect to this title online; UW restricted, 1999. http://hdl.handle.net/1773/8552.

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16

Han, Jin Hee. "Isolation of phenylalanine hydroxylases and enzymatic studies with 3- and 4- pyridylalanine." Diss., Georgia Institute of Technology, 1988. http://hdl.handle.net/1853/27313.

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17

Rugunanan, Rajan Anil. "Intersolid pyrotechnic reactions of silicon." Thesis, Rhodes University, 1992. http://hdl.handle.net/10962/d1015571.

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A study of the role of different oxidants with silicon as the fuel in simple binary pyrotechnic compositions is reported. Several oxidants were examined, but only three (Sb₂0₃, Fe₂0₃ and Sn0₂) satisfied the restrictions that the combustion temperatures should be below the melting point of platinum/rhodium thermocouples (1760°C), that burning rates should not exceed the response of the thermocouples, and that burning should occur without significant mass-transport. A fourth oxidant, KN0₃, was selected on account of its low melting point and general importance as a pyrotechnic oxidant. The oxidation of silicon in the presence of either Sb₂0₃ or KN0₃ could be identified from thermal analysis curves. No thermal events were noted when Si/Sn0₂ and SiFe₂0₃ compositions were heated under similar conditions. The oxidation of Si powder in oxygen was also studied. All four binary systems sustained burning over a reasonably wide range of compositions. The range of burning rates measured (2 to 35 mm s⁻¹) depended on the oxidant used. Fe₂0₃ and Sb₂0₃ gave slow burning mixtures compared to Sn0₂ and to KN0₃ compositions with a high Si content. Burning rates generally increased with increasing specific surface area of silicon, but decreased in the presence of inert diluents and moisture. The burning rates of the Si/Fe₂0₃ and Si/Sn0₂ systems increased with increasing compaction of the samples. Kinetic parameters derived from the temperature proftles recorded during combustion were generally low (6 to 37 kJ mol⁻¹). This is in keeping with proposals that burning is diffusion controlled. The values of kinetic parameters derived from thermal analysis curves were considerably greater ( > 250 kJ mol⁻¹). Two other fuels, FeSi₇ and CaSi₂, gave similar thermal analysis curves when used instead of silicon. There were considerable differences in the burning rates for binary mixtures of these fuels compared to silicon. Ternary systems with two fuels or two oxidants showed that only limited interaction occurs during thermal analysis. The use of a second fuel or oxidant did, however, modify the burning behaviour considerably. Other techniques used in this study to probe the details of the reaction processes included bomb calorimetry, measurement of thermal conductivities, infrared spectroscopy, X-ray diffraction and scanning electron micoscropy.

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18

Tanha, Matteus. "Development and Application of Efficient Data Analytic Methods in Quantum Chemistry." Research Showcase @ CMU, 2015. http://repository.cmu.edu/dissertations/1028.

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This work presents systematical approaches to improve both the application and theory of quantum chemical methods. Semi-empirical and ab initio quantum chemical methods are used to model fluorescent dyes for bio-imaging. A new approach to development of semiempirical quantum chemical methods is explored, and imitation learning is used to accelerate convergence of self consistent field calculations. The fluorescence of the SKC-513 dye is highly sensitive to the binding of K+ ion. Computations reveal that, in the absence of K+, excitation is to two nearly-degenerate states, a neutral (N) excited state with high oscillator strength and a charge-transfer (CT) state with lower oscillator strength. Binding of K+ raises the CT state far above the N state, shutting down a non-radiative pathway mediated by the CT state. This rationalizes the high sensitivity of the quantum yield to ion binding. Computations on a series of thiazole orange derivatives are used to successfully account for the observed spectral shifts through frontier orbital analysis. A means to take advantage of molecular similarity to lower the computational cost of electronic structure theory is explored, in which parameters are embedded into a low-cost, low-level (LL) ab initio model and adjusted to obtain agreement with results from a higher-level (HL) ab initio model. In the parametrized LL (pLL) model, selected matrix elements of the Hamiltonian are scaled by factors that depend on element types. Various approaches to scaling, including making parameters sensitive to atomic charges and bond orders, are explored. The models are trained on ethane and ethylene, substituted with -NH2, -OH and -F, and tested on substituted propane, propylene and t-butane. The molecules are distorted and placed in electrostatic fields. Fitted properties include total and decomposed energies, frontier orbital energies, and interactions with test charges. The best-performing model forms reduce the root mean square (RMS) difference between the HL and LL energy predictions by over 85% on the training data and over 75% on the test data. Many computational methods, including self consistent field calculations in quantum chemistry, work by fixed-point iteration—repeatedly applying a given update function until convergence is achieved. A means to accelerate fixed-point iteration via imitation learning is explored. The approach is simple and needs only black-box access to the original update function. Experiments show that the approach successfully accelerates Hartree-Fock convergence, and that policies trained on one set of molecules transfer successfully to other molecules of the same general class. Imitation learning also leads to more-robust transfer than alternative methods that do not take into account the distribution of states induced by the learned policies.

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19

Aldridge, Paul K. "Spectroscopic instrumentation for process analytical chemistry /." Thesis, Connect to this title online; UW restricted, 1991. http://hdl.handle.net/1773/8512.

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20

Brown, Frank Reber. "Analytical applications of flow injection analysis." Diss., The University of Arizona, 1987. http://hdl.handle.net/10150/184254.

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The rate of oxidation of copper metal to copper (I) by copper (II) in the presence of organic ligands has been determined for a variety of ligands using a flow injection analysis system to sample the reaction. The results obtained using the FIA sampling method compare favorably with those obtained in eariler work when allyl alcohol was used as the ligand. The mechanism proposed in that earlier work has been shown to be a general mechanism for the oxidation of copper metal in the presence of complexing ligands. It was found that some ligands increase the rate of the reaction beyond the ability of conventional FIA to sample many data points before the reaction reaches equilibrium. A method has been developed that allows for more rapid sampling of the reaction mixture by the FIA system, resulting in overlapping FIA peaks. These overlapping peaks can then be deconvolved by an iterative curve fitting/digital subtraction technique in which each peak in the FIA output is fitted to a model function and subtracted from the output, thus removing its effect on the peak height of subsequent peaks. The iodination of acetylacetone in acidic solution was also studied by the fast injection FIA technique. Iodine was generated coulometrically in the solution containing acetylacetone and hydrochloric acid. By this method, the keto-enol equilibrium constant of acetylacetone was determined over a range of pH's. They ranged from 2.3 x 10⁻⁵ at a pH of 2.63 to 1.8 x 10⁻⁴ at a pH of 4.03. It was also found that the reaction was first order with respect to the acetylacetone concentration.

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21

Li, Fang Owens Kevin G. "Development of a genetic algorithm-correlation analysis (GA/CA) program for classification of chemical compounds using mass spectral data /." Philadelphia, Pa. : Drexel University, 2008. http://hdl.handle.net/1860/2803.

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22

Tang, Xiaoting. "New analytical tools for systems biology." Online access for everyone, 2006. http://www.dissertations.wsu.edu/Dissertations/Fall2006/x_tang_081706.pdf.

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23

Brückner, Carsten Albrecht. "Rapid chromatographic analysis using novel detection systems and chemometric techniques /." Thesis, Connect to this title online; UW restricted, 1998. http://hdl.handle.net/1773/11573.

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24

Ovenden, Simon P. B. "Preparation of a natural product extract library for investigation against disease states specific to defence health a mini long range research project /." Fishermans Bend Victoria : Defence Science and Technology Organisation, 2009. http://hdl.handle.net/1947/9861.

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25

Krebs, Richard A. "Proteorhodopsin a study on its photocycle and its place in the evolution of the bacteriorhodopsin superfamily /." Related electronic resource: Current Research at SU : database of SU dissertations, recent titles available full text, 2006. http://proquest.umi.com/login?COPT=REJTPTU0NWQmSU5UPTAmVkVSPTI=&clientId=3739.

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26

Vinjamuri, Anil Kiran Kumar. "A Selectivity Study on the Use of Caffeine and Theobromine Imprinted Polypyrrole Surface Electrodes." TopSCHOLAR®, 2008. http://digitalcommons.wku.edu/theses/5/.

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27

Guo, Changning Nafie Laurence A. Freedman Teresa B. "Enantiomeric excess determination and reaction monitoring of chiral molecules using near-infrared and mid-infrared vibrational circular dichroism." Related electronic resource: Current Research at SU : database of SU dissertations, recent titles available full text, 2004. http://wwwlib.umi.com/cr/syr/main.

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28

Zhao, Taiping Nafie Laurence A. Freedman Teresa B. "Near-infrared vibrational circular dichroism of polypeptides and small pharmaceutical molecules." Related electronic resource: Current Research at SU : database of SU dissertations, recent titles available full text, 2004. http://wwwlib.umi.com/cr/syr/main.

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29

Grange, Andrew H. "Medium resolution atmospheric pressure ionization mass spectrometry /." Full text open access at:, 1988. http://content.ohsu.edu/u?/etd,158.

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30

Ho, Yee Man. "Development of sample pretreatment methods for complex analytical matrices." HKBU Institutional Repository, 2013. http://repository.hkbu.edu.hk/etd_ra/1510.

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31

Hall, Bradley John. "Development of solid phase microextraction (SPME) and matrix assisted laser desorption ionization (MALDI) with quadrupole ion trap mass spectrometry for analytical applications /." Digital version accessible at:, 1998. http://wwwlib.umi.com/cr/utexas/main.

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32

Joa, Susan Louise. "Electrochemical and Raman spectroscopic investigations of butanol isomers at silver and gold electrodes." Diss., The University of Arizona, 1992. http://hdl.handle.net/10150/185967.

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The overall goal of this research is to characterize the solvent and electrolyte structure of the nonaqueous electrochemical double layer in the isomers of butanol on Ag and Au electrodes. Electrochemical and spectroscopic methods are employed to obtain structural information about the interface. In order to gain a better understanding of the Raman vibrational assignments of these alcohols, the Raman vibrational assignments were determined for a series of n-alcohols (n = 3-6, 8, 12, 14, and 18) in the spectral region from 700 to 1320 cm⁻¹ and 2800 to 3000 cm⁻¹. Solvent structure of the butanol isomers, 1-butanol, 2-butanol, and iso-butanol, were determined in-situ on rough Ag and Au electrodes using surface enhanced Raman scattering. Surface Raman selection rules were used to determine the average molecular orientation of these solvents at the electrode under potential control. The electrolyte structure in the nonaqueous electrochemical double layer has been determined using surface enhanced Raman scattering and differential capacitance measurements. Surface enhanced Raman scattering studies of the electrolyte structure were focused on probing the molecules solvating the cation and anion species, namely the alcohol and water impurity species. The ν(O-H) bands from these solvation species were monitored in these nonaqueous systems under potential control. These ν(O-H) bands distinctly describe the behavior of the LiClO₄, LiCl, LiBr, and LiI at the electrode under potential control. Differential capacitance measurements using an AC impedance method were performed to quantify anion coverages at smooth Ag electrodes in the butanol isomers. Cl⁻ and Br⁻ coverages were determined in the butanol isomers. This technique, coupled with SERS, provides complementary information about the electrolyte structure at the nonaqueous electrochemical double layer. The solvent and electrolyte structure is also determined ex-situ on emersed rough and smooth Ag and Au electrodes using Raman spectroscopy. Upon emersion of the electrodes into an inert Ar environment, solvent orientation and electrolyte behavior are investigated using Raman spectroscopy. These studies demonstrate both the utility of using Raman spectroscopy to probe emersed electrodes and the validity of emersing the electrode while preserving the double layer structure.

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33

Williams, Kristina Charlene. "Direct Inject Mass Spectrometry for Illicit Chemistry Detection and Characterization." Thesis, University of North Texas, 2016. https://digital.library.unt.edu/ark:/67531/metadc849747/.

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The field of direct inject mass spectrometry includes a massive host of ambient ionization techniques that are especially useful for forensic analysts. Whether the sample is trace amounts of drugs or explosives or bulk amounts of synthetic drugs from a clandestine laboratory, the analysis of forensic evidence requires minimal sample preparation, evidence preservation, and high sensitivity. Direct inject mass spectrometry techniques can rarely provide all of these. Direct analyte-probed nanoextraction coupled to nanospray ionization mass spectrometry, however, is certainly capable of achieving these goals. As a multifaceted tool developed in the Verbeck laboratory, many forensic applications have since been investigated (trace drug and explosives analysis). Direct inject mass spectrometry can also be easily coupled to assays to obtain additional information about the analytes in question. By performing a parallel artificial membrane assay or a cell membrane stationary phase extraction prior to direct infusion of the sample, membrane permeability data and receptor activity data can be obtained in addition to the mass spectral data that was already being collected. This is particularly useful for characterizing illicit drugs and their analogues for a biologically relevant way to schedule new psychoactive substances.

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34

Erickson, Brice Carl. "Multicomponent flow injection analysis and quantitative infrared emission spectroscopy : chemometric applications /." Thesis, Connect to this title online; UW restricted, 1988. http://hdl.handle.net/1773/8633.

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35

Sobocinski, Raymond Louis. "Electrochemical and Raman spectroscopic investigations of in situ and emersed silver-alcohol electrochemical interfaces." Diss., The University of Arizona, 1991. http://hdl.handle.net/10150/185476.

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The overall goal of this research is to characterize the potential-dependent structure and composition of the alcohol-Ag electrochemical interface. The approach involves the use of a variety of electrochemical and spectroscopic tools to arrive at a consistent model for a series of straight-chain alcohols (methanol, ethanol, 1-propanol, and 1-pentanol) at Ag electrodes. There are essentially four areas of investigation presented in this dissertation. The first portion of this work has been directed at the development of charge coupled device detection in Raman spectroscopy so that many of the interface investigations could be performed. The advantages and limitations of these detectors in Raman spectroscopy are addressed. The second area involves the characterization of in-situ alcohol-Ag electrochemical interfaces using Raman spectroscopy and associated surface selection rules for the evaluation of solvent orientation and bonding. Since the series of alcohols offers a systematic variation in solvent properties, these studies provide substantial insight regarding some of the chemical interactions which can dictate orientation. The development of emersed electrode technologies is also presented as a means to improve selectivity for surface molecular species over bulk molecular species. The utility of this approach is demonstrated for a variety of straight-chain alcohols at both rough and smooth Ag electrodes. Conditions for emersing the molecular interface, intact, under potential control are presented. Finally, double layer capacitance measurements are performed to offer additional insight regarding alcohol solvent structure and interfacial composition as a function of electrode potential. In addition, capacitance-potential plots are used along with the Hurwitz-Parsons analysis to determine absolute surface coverage of Br⁻ as a function of electrode potential. These results are correlated with the Raman spectroscopic results to obtain a consistent model for the structure and composition of the alcohol-Ag electrochemical interface.

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36

Bairu, Semere Ghebru. "Diamond paste based electrodes for inorganic analysis." Diss., Pretoria : [s.n.], 2003. http://hdl.handle.net/2263/27268.

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Differential pulse voltammetry is one of the most widely used analytical polarographic techniques especially for trace inorganic analysis. Up to now mercury electrode and different types of carbon electrodes were used for such analysis. The emphasis of the present dissertation is on the design of a new class of electrodes, namely mono crystalline diamond paste based electrodes, to be used in differential pulse voltammetry for trace analysis of inorganic compounds. Monocrystalline diamond and boron doped polycrystalline diamond based electrodes exhibit several superior electrochemical properties that are significantly different from those of other carbon allotropes based electrodes, e.g., glassy carbon electrodes, highly oriented pyrolytic graphite based electrodes, which have been widely used for many years. The advantages are: (a) lower background currents and noise signals, which lead to improve SIB and SIN ratios, and lower detection limits; (b) good electrochemical activity ( pre-treatment is not necessary); (c) wide electrochemical potential window in aqueous media; (d) very low capacitance; ( e) extreme electrochemical stability; and (f) high reproducibility of analytical information. Furthermore, later studies shown the superiority of the mono crystalline diamond as electrode material due to high mobilities measured for electrons and holes. The design selected for the electrodes is simple, fast and reproducible. The diamond powder was mixed with paraffine oil to give the diamond paste used as electroactive material in the electrodes. The results obtained by employing the diamond paste based electrodes proved a high sensitivity, selectivity, accuracy and high reliability. These characteristics made them suitable to be used for the analysis of different cations (e.g., Fe(ll), Fe(Ill), Cr(Ill), Cr(VI), Pb(ll), Ag(I)) as well as of anions (e.g., iodide) in pharmaceutical, food and environmental matricies.
Dissertation (MSc (Chemistry))--University of Pretoria, 2006.
Chemistry
unrestricted

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37

Buchanan, Bruce Randall. "Compatability of optical-fiber measurements with near-infrared and visible analysis /." Thesis, Connect to this title online; UW restricted, 1987. http://hdl.handle.net/1773/11591.

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38

Franke, Mark Douglas. "An investigation of the kinetics and mechanisms in the dissolution of alumina in aqueous sulfuric acid." Thesis, Georgia Institute of Technology, 1985. http://hdl.handle.net/1853/10921.

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39

Tribelhorn, Michael John. "Reactions of iron- and zinc-fuelled pyrotechnic systems." Thesis, Rhodes University, 1995. http://hdl.handle.net/10962/d1005003.

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A major industrial use of pyrotechnic compositions is as delay fuses in electric detonators. Suitable delay times may be achieved through (i) choice of chemical components (ii) adjustment of composition of the system chosen and, finally, (iii) adjustment of the length of fuse used. This study forms part of a survey of binary fuel/oxidant combinations in an attempt to provide some fundamental information on the first step above: (i) choice of chemical components. The complete survey has included studies of a single fuel in combination with one of a variety of oxidants, and studies of the oxidation of one of several different fuels separately by barium peroxide and strontium peroxide. This study is part of this second approach and the fuels chosen were iron and zinc powders, mainly for chemical reasons (including the potential for use of thermomagnetometry on the iron systems), but also for possible environmental advantages. The mixed oxide products of pyrotechnic combustion could also have some scientific and/or commercial value. The techniques used included thermal analyses of mixtures and their individual components, and measurements of temperature-time profiles during combustion. Thermodynamic and kinetic information was obtained under a variety of conditions and scanning electron microscopy and X-ray diffraction and microprobe analyses provided additional information. Possible mechanisms of reactions are discussed in detail. The practical conclusions were that any potential use which the Fe/peroxide systems may have as delay compositions, with burning-rates of from 3-30 mm s⁻¹, is offset by the susceptibility of the oxidants to reaction with water and CO₂ in the atmosphere. The Zn/BaO₂ and Zn/SrO₂ systems did not burn under compaction, and combustion of uncompacted powders was erratic. Zinc liquid (and probably zinc vapour) take part in the reaction and the gaseous nature of the combustion makes zinc-fuelled pyrotechnic systems unsuitable for delay applications. All the techniques used showed the heterogeneity of the solid residues of combustion. If these residues were to be of any value, they would need further conventional treatment involving grinding of the residue, possible adjustment of compositions, and calcining to produce uniform materials.

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40

Kuhns, David W. "The viability of multiple bubble sonoluminescence for analytical applications /." Thesis, Connect to this title online; UW restricted, 1997. http://hdl.handle.net/1773/11590.

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41

Fraga, Carlos Gerardo. "Comprehensive two-dimensional gas chromatography and chemometrics for the analysis of complex mixtures /." Thesis, Connect to this title online; UW restricted, 2000. http://hdl.handle.net/1773/8690.

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42

Rivera-Laos, Mario Ernesto. "Complexing properties of 2,3-dimercaptosuccinic acid and its monomethyl and dimethyl esters." Diss., The University of Arizona, 1991. http://hdl.handle.net/10150/185451.

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Metal complexes of meso-dimercaptosuccinic (DMSA) acid were studied by potentiometric and infrared methods. The coordination sites were found to be metal dependent. In the cases of Pb²⁺ and Cd²⁺, one oxygen and one sulfur act as donors; in the case of Hg²⁺, two sulfur atoms act as donors. The solubilities of the chelates were found to be pH dependent. When the uncoordinated sulfhydryl and carboxylic acid groups dissociate, the chelates dissolve and remain in aqueous solution. In the case of racemic-DMSA, two types of Pb²⁺ chelates were isolated: one in which rac-DMSA is coordinated to Pb²⁺ via one oxygen and one sulfur atom and the other in which the Pb²⁺ is coordinated via two sulfur atoms. The monomethyl ester and the dimethyl ester of meso-DMSA (MoMeDMSA and DiMeDMSA, respectively) were synthesized and their metal chelates with Pb²⁺, Cd²⁺, and Hg²⁺ studied. Esterification of meso-DMSA was found to change its biological properties. Both compounds, MoMeDMSA and DiMeDMSA, increased the biliary excretion of cadmium, which strongly suggests that the two derivatives of meso-DMSA enter the hepatocyte. The acid dissociation constants of the chelating agents and the uncoordinated groups in its metal chelates were determined. The results suggested that these acid-base properties in addition to the polarity of the chelating agent contribute to the effectiveness in the mobilization of intracellular deposits of cadmium. The dimethyl ester of DMSA was found to compete effectively with metallothionein for Cd²⁺ and Zn²⁺ ions by ¹H NMR spectroscopy. The structures of the metal chelates formed upon interaction of DiMeDMSA and Cd²⁺, or Zn²⁺ in solution at physiological pH were determined by multinuclear magnetic resonance spectroscopy. Mononuclear complexes were found to be formed. In these complexes, the metal ions are tetrahedrally coordinated by four thiolate groups from two DiMeDMSA molecules.

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43

Palmer, Christopher Paul. "Effects of orientation and mobility of surface modifiers on the selectivity and efficiency of chemical interactions at selected chemically modified surfaces." Diss., The University of Arizona, 1991. http://hdl.handle.net/10150/185668.

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Several surfaces chemically modified with a variety of surface modifiers have been studied using chromatographic, nuclear magnetic resonance, and computational techniques. The goal was to determine the effect of modifier structure on the solvation, selectivity, and efficiency of chemical interactions occurring at chemically modified surfaces. Oleyldimethylchlorosilane has been synthesized and bonded to silica to determine the effect of a conformational change at the center of the chain on the behavior of the entire surface. It has been shown with these studies that the configuration of the modifier plays an important role in determining the selectivity of chemical interactions at modified surfaces. By comparison with phospholipid bilayers, of the structure, solvation and dynamics of alkylmodified silicas has been achieved. Octyldimethylsilyl- and octadecyldimethylsilyl-modified silicas have been further reacted with t-butyltrichlorosilane, t-butyldimethylchlorosilane and trimethylchlorosilane to determine both the utility of t-butyltrichlorosilane as an end-capping reagent and the extent to which solvation of the near-surface region affects the performance of these surfaces. It was shown that the orientation and solvation of modifiers at the near surface has a profound effect on the selectivity and efficiency of chemical interactions at the surface. Sepharose gels modified with iminodiacetic acid have been studied by titrimetric and spectroscopic means. A model compound has been synthesized and characterized in solution. The results have led to a better understanding of the behavior of chelating agents at sepharose surfaces and the effects of immobilization on the behavior of ligands at a surface. Finally, quartz crystalline microbalances modified with physisorbed polymer layers have been studied by correspondence analysis. In this case, it has been shown that the polymer backbone of the modifying agent plays an important role in determining the selectivity of the modified surfaces. Together these studies have led to a more complete understanding of the effects of the structure and solvation of modified surfaces on the selectivity and efficiency of chemical interactions occurring at those surfaces. These observations apply to interactions occurring at chromatographic stationary phases and to interactions at chemically modified surfaces in general.

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44

Smith, David Paul. "Syntheses and characterization of compounds of niobium and tantalum with phenylimido and phenoxide ligation." Diss., The University of Arizona, 1991. http://hdl.handle.net/10150/185669.

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The metallacyclopentadiene (DIPp)₂CITa(CCMe₃=CHCH=CCMe₃) (α, α') (DIPP=2,6-diisopropylphenoxide) is isolated from the 2 electron reduction of Ta(DIPP)₂CI₃(OEt₂) in the presence of excess Me₃CC=CH. The α, α' isomer represents the kinetic product of this reaction since it can be thermolyzed to produce (DIPP)₂CITa(CCMe₃=CHCCMe₃=CH) (α, β’). The reactivity of these two isomers toward the addition of ethylene and alkynes has been investigated and found to be driven primarily by steric effects with the less hindered α, β’ isomer showing a more comprehensive chemistry. The rearrangement of α, α' to α, β’ was followed through several kinetic and mechanistic studies. This data support a mechanism involving dissociation of the a,a' isomer to the metallacyclopropene, (DIPP)₂CITa(HC=CCMe₃), and free Me₃CC=CH. These intermediates then recouple to form the thermodynamic product, the α, β’ isomer. The reaction of TA(DIPP)₃Cl₂(OEt₂) with quinoline or 6-methylquinoline (HC) produces the ligand exchange product (η¹-HC)Ta(DIPP)₃CI₂, the 2 electron reduction of either of these products yields [η²-(N,C)-HC]Ta(DIPP)₃ which can be isolated as the phosphine complex [η²-(N,C)-HC]Ta(DIPP)₃(PMe₃) upon reaction with trimethylphosphine. The reaction of either [η²-(N,C)-quinoline]Ta(DIPP)₃ or [η²-(N,C)quinoline] Ta(DIPP)₃(PMe₃) with hydrogen both in the presence and absence of Pd/C produces 1,2,3,4-tetrahydroquinoline and 2,2'-bisquinoline. The production of these compounds implicates the η²-(N,C) bonding mode in selective hydrogenation of heterocycles and ortho functionalization. The reaction of Nb(NEt₂)₂CI₃ with two equivalents of LiNHMes (Mes=2,4,6- C₆H₂Me₃) followed by addition of pyridine produces Nb(NMes)₂CI(py)₂. The reaction of Nb(NEt₂)₂CI₃ with 6 equivalents of LiNHMes produces the first tris imido complex of group 5, [(THF)₂Li][Nb(NMes)₃(NHMes)]. Comparable chemistry is seen with Ta. [(THF)₂Li][Nb(NMes)₃(NHMes)] reacts with lithium alkyls under kinetic conditions to produce [(THF)2Li][Nb(NMes)₃(R)] (R=Me, ⁿSu, ᵗSu, Me₃SiCH₂). Under thermodynamic conditions, however, the reaction of [(THF)₂Li][Nb(NMes)₃(NHMes)] with ᵗBuLi yields the first tetrakis imido complex of group 5, [(THF)₄Li₃][Nb(NMes)₄]

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45

Bryant, Mark Alan. "Surface Raman scattering of alkanethiols at silver and gold." Diss., The University of Arizona, 1991. http://hdl.handle.net/10150/185702.

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The overall goal of this research is a comprehensive characterization of self-assembled alkanethiol monolayer films at Ag and Au surfaces. A combination of surface Raman spectroscopy and electrochemistry is employed to study several important aspects of these films. Raman vibrational assignments for a series of n-alkanethiols (n = 4, 5, 8, 9, 10, 12, 16, and 18 for C(n)H(2n+1)SH) are determined in the spectral regions from 600 to 1300 cm⁻¹ and 2800 to 3000 cm⁻¹. Particular emphasis is given to the trans (T) and gauche (G) ν(C-S) and ν(C-C) bands and the ν(C-H) bands. Surface Raman spectra of n-alkanethiol films at electrochemically roughened and mechanically polished, polycrystalline Ag and Au surfaces are presented. Strong enhancements of surface Raman scattering are realized at roughened surfaces, while less enhancement is observed at the mechanically polished surfaces. The conformational order of these films at these surfaces is evaluated by the determination of T and G bands present in the spectra. The orientation of these films at Ag and Au is determined through the use of surface Raman selection rules. A method is developed for the determination of orientation of C-S and C-C bonds and methyl groups. The orientations deduced using the spectral results from each of these regions are found to be self-consistent. Different orientations are deduced for alkanethiol films at Ag and Au surfaces and are proposed to be influenced by metal-S bonding. The orientations can be altered in the electrochemical environment by control of the applied potential of these metal substrates. The potential-dependent behavior is correlated with the potential of zero-excess charge (PZC) of these metals. Defect structure of these films at Ag surfaces with various surface morphologies is evaluated with Pb deposition studies. Gross films defects are evaluated with Pb underpotential deposition and ion penetration is studied with bulk Pb deposition. Finally, surface Raman spectra of monolayer films at non-enhancing surfaces are presented. Spectra for butanethiol at single-crystal Ag surfaces and butanethiol and thiophenol at mechanically polished, polycrystalline Pt surfaces show the utility of Raman spectroscopy for studying films at a variety of surfaces.

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46

Pomeroy, Robert S. "Spark emission spectroscopy utilizing CID array detectors and related studies." Diss., The University of Arizona, 1992. http://hdl.handle.net/10150/185942.

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In the analysis of solid samples, there are two distinct advantages to performing direct analysis on the solid: (1) minimal sample preparation and (2) avoids potential sample contamination from the reagents used in the dissolution process. The two most common optical techniques for direct solids analysis are arc and spark emission spectroscopy. The most important drawback associated with arc and spark spectroscopy is in the acquistion and interpretation of the spectrum. The development of a custom echelle spectrometer with Charge Injection Device (CID) array detection carried out in these laboratories should be particularly well suited for arc and spark emission spectroscopy. CIDs exhibit many of the best characteristics of photographic film and PMT detection while providing the added advantage of nondestructive readout and Random Access Integration (RAI). This thesis describes the work coupling a spark source to a CID/echelle spectrometer. When properly shielded, the sensitive electronics of the CID function normally in the presence of the spark discharge. The potential for this system to be able to handle the wide variety of spectroscopic situations resulting from the complex spectra typically obtained with this type of excitation is attributed to the flexibility of the instrument which allows the use of alternate line for analysis and internal standard calibration. Additionally, the use of multiple lines has been applied to comparative analysis, monitoring the background for changes in excitation, and determination of the optimum lines to be used for quantification. Effective utilization of the large database of spectral information has lead to the development of sophisticated expert systems such as automated qualitative and semiquantitative analysis routines. Preliminary work with an astigmatism free imaging spectrograph and a Charge Coupled Device (CCD) array detector has shown the ease with which spatial and spectral maps of emission source can be generated. Observation of the spark discharge process in a hope of gaining a clearer picture of the mechanisms of sample excitation seems to be the most rational approach to ultimately obtaining control over the spark process and alleviating the problems associated with sparks excitation.

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47

Surakitbanharn, Yosyong. "The efficient separation of platinum group metals using centrifugal partition chromatography." Diss., The University of Arizona, 1992. http://hdl.handle.net/10150/186074.

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Centrifugal Partition Chromatography (CPC) is a multistage liquid-liquid countercurrent distribution technique which utilizes rotating teflon cartridges to hold a liquid phase stationary while the other liquid phase is pumped at a constant flow rate. It has been demonstrated to be a valuable technique for the base line separations of families of metal ions such as the platinum group metals (PGM)--Pt, Pd, Rh and Ir. The separations of these metals as their anionic chloro complexes were achieved using the heptane-water phase pair with a stable and relatively inexpensive extractant trioctylphosphine oxide (TOPO) functioning as a ligand in its neutral form and as a cation in its protonated form. A striking feature of the chromatograms of the complexes and ion pairs were their much poorer efficiencies compared to the efficiency of an organic analyte like 3-picoline under identical distribution rations. The inefficiencies of the PGM separations were also a function of the concentrations of the aqueous and organic phase components. These inefficiencies could be attributed to slow kinetics of the back extraction of the complexes and ion pairs and could be used to derive the mechanisms of these slow chemical kinetic steps. A correlation was established for the Pd(II) system between the CPC inefficiencies and the half lives of the slow reactions measured independently by stopped flow in micelles. This correlation was utilized to derive the rate constants for the back extraction of the TOPO complexes and ion pairs of Pt and Ir. The mechanisms of the extraction reactions were derived using the principle of microscopic reversibility based on the mechanisms of the back extraction reactions. This was then used to obtain estimates for the rate constants for the extraction reactions as well. The PGM were thus separated and their equilibrium and kinetics (extraction and back extraction) completely characterized using CPC. This is a significant development with CPC because such complete equilibrium and kinetic characterizations are hard to achieve with conventional liquid chromatographic techniques.

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48

Johnson, David Duane. "The role of structure, orientation and composition of chemically tailored surfaces in differential migration techniques." Diss., The University of Arizona, 1993. http://hdl.handle.net/10150/186124.

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Control of separation processes which occur at solid-liquid interfaces can be achieved by understanding the interactions which occur at these interfaces. Because of its many desirable bulk characteristics, silica is the solid support of choice for many separation applications. Utilizing various differential migration techniques, control of the separation at different silica surfaces was investigated through irreversible chemical modification of the surface, the use of a dynamic modifier, and through physicochemical alteration of the silica surface. A new bonded phase was prepared by reacting γ-(3,4 methylene dioxyphenyl) propyldimethylchlorosilane--synthesized from safrole and dimethylchlorosilane--with porous silica yielding a non-traditional bonded phase which maintained some similarity with traditional alkyl bonded phases while also possessing distinct differences. Through the use of diagnostic chromatography this surface was shown to demonstrate unique selectivity towards polar analytes when compared with an octyl and phenyl surface under the same solvation conditions. A thermal study utilizing diagnostic chromatography was also used to demonstrate the impact of orientation on retention at this surface. The large scale separation of C₆₀ and C₇₀ was accomplished using a batch process utilizing a traditional bonded phase under normal phase condiitons. Both the kinetics and thermodynamics of the separation were improved through the addition of a dynamic modifier to the running solvent. Macroscopic quantities of pure C₆₀ and C₇₀ are readily obtained using this approach. Control of electroosmotic flow in silica capillaries was demonstrated by chemically tailoring the surface with a series of novel silane modifiers. Although changes in electroosmotic flow velocity were observed, the ultimate goal of flow reversal was not achieved. Finally, a new ISRP surface was prepared by monoatomic oxygen treatment of large (63-90μm) irregularly shaped modified silica particles. This new ISRP was evaluated to determine if the more technically demanding but practically useful treatment of high efficiency particles for use in direct injection HPLC should be pursued.

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49

Fung, Kee Fung Carol Alison. "The behavior of water at the modified silica interface." Diss., The University of Arizona, 1993. http://hdl.handle.net/10150/186134.

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The behavior of water at the modified silica interface was studied with Differential Scanning Calorimetry. A model for the interaction of water with the surface of silica was evolved to include the influence of the silica surface, the modification of the surface with hydrophobic and hydrophilic functional groups, and the presence of organic solvents. Initial studies involved the investigation of the melting behavior of water at the surface of unmodified silica. This was studied as a function of pore size, specific surface area, surface activity and specific pore volume. The perturbation of the water in the near surface region by interactions with the surface silanols and the curvature of the silica surface resulted in the observation of a melting peak was that was significantly different than the bulk water behavior. Changes to this peak were observed as a function of the modification of the silica surface with alkyl chains of varying chain length, and variations in the bonding density of these chains. As a consequence of the modification of the surface, the water was able to interact with only isolated silanol sites and this was reflected in a shift in the melting peaks. The deactivation of the silanol sites occurred both through the formation of the silyl ether linkage to the modifier, and the blocking of the surface by the hydrophobic alkyl chains. The changes in the behavior of water at the modified silica interface in the presence of organic solvents were also investigated. It was found that the ability of the organic solvent to hydrogen bond to the silica surface and with water was the greatest contributor to the changes in the melting behavior of the water. The behavior of water at the silica interface modified with hydrophilic functional groups was investigated. It was found that the functional groups that could hydrogen bond with the water could also influence its melting behavior. As a consequence the layer of water affected by the surface was extended further away from the surface than was observed with unmodified silica.

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50

Van, Orden Steven Lee. "Mechanistic investigations of gas phase ion-molecule reactions using Fourier transform ion cyclotron resonance mass spectrometry." Diss., The University of Arizona, 1993. http://hdl.handle.net/10150/186137.

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Studies of the mechanisms and energetics of a variety ion-molecule reactions involving organometallic and organic ions, have been performed using Fourier transform ion cyclotron resonance mass spectrometry (FTMS). The bond activation processes of V⁺, VO⁺, VOH⁺, and VOCH₃⁺ with water and methanol were investigated in detail. All ions are observed to preferentially activate the C-O bond in methanol, however C-H and O-H bond cleavage are also observed. The addition of the oxo, hydroxo, and methoxo ligands is found to significantly effect the intrinsic reactivity of the ions, relative to V⁺. The reactions of V(CO)₅⁻ with a wide variety of molecules have revealed mechanistic details of the oxidative addition and ligand switching reactions. Steric effects are proposed to account for the selective reactivity of V(CO)₅⁻ with alcohols and amines. Studies of ligand substitution reactions support an electron transfer initiated mechanism, implying that V(CO)₅⁻ has a triplet ground state and a trigonal bipyramidal structure. The chlorine atom transfer reactions of V(CO)₅⁻ with chloromethanes display a correlation with C-CI bond strength, suggesting the mechanism is initiated by oxidative addition of the C-C1 bond or involves a direct chlorine atom transfer. The decomposition of metallocarboxylate anions ([M(CO)ₓ₋₁CO₂]⁻) was studied in an effort to understand the production of CO₂ by metal carbonyl compounds, proposed as intermediates in the Water-Gas shift reaction. The nascent [M(CO)ₓ₋₁C0₂]⁻*, formed by nucleophilic addition of 0⁻ to M(CO)ₓ (M=Pe, Cr, V), is observed to undergo exclusive loss of CO₂ without subsequent decomposition of the product metal carbonyl anion (M(CO)ₓ₋₁⁻) The reaction of P AHs with O⁻ and O₂⁻ were studied, to investigate the potential of isomer differentiation by chemical ionization. These reactions are characterized by a number of reactive pathways, demonstrating the ability to distinguish isomers which cannot be differentiated by other ionization techniques. Kinetic energy release measurements of the S(N)2 reactions of F⁻ with CH3CI, C₆H₅CI, and CH₃COCl have been made using KEICR. The F⁻/CH₃Cl reaction results in a non-statistical energy disposal. The reaction is proposed to proceed by a direct mechanism.

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