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Dissertations / Theses on the topic 'Metal atom chemistry'
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1
Tovey, R. C. "Studies in metal vapour synthesis." Thesis, University of Oxford, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.375325.
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Ren, Wendong. "Photoinduced Atom Transfer Radical Polymerization." University of Akron / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=akron1619122320374689.
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Harris, Neil. "A matrix isolation study of main group and transition metal atom cryochemistry." Thesis, University of Hull, 2001. http://hydra.hull.ac.uk/resources/hull:12359.
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The majority of the work described in this thesis is concerned with the isolation of transition metal and main group atoms in dilute reactive ligand matrices. The previously uncharacterised matrix isolated species were characterised using IR, UV-Vis-NIR and XAFS spectroscopic techniques. Various metal atom sources were investigated for the production and subsequent isolation of atomic species in both inert and reactive ligand matrices. Some 4d and 5d transition metals atoms were produced from a hollow cathode sputtering source (laser ablation was also employed as an atom source in some of the work) and isolated in argon matrices. The isolation of both platinum and palladium atoms in chlorine containing argon matrices has been shown to result in the formation of linear PtCl₂ and PdCl₂ molecules. The isolation of gold atoms has led to the formation of a monomeric chloride, suspected to be either AuCl3 or AuCI₂.The structure of the silver chloride remains undetennined. The pseudo-gas phase structure of these monomeric species is presented for the first time. In addition to this work tellurium atoms have been generated from the photodecomposition of matrix isolated H₂Te. The use of CO containing matrices has led to the isolation and characterisation of carbonyl telluride, OCTe, the structure and composition of which (either in the solid or gas phase) is presented for the first time. In complementary work, an investigation into carbonyl complexes formed on isolation of some 3d transition metal bromides in dilute carbon monoxide / argon matrices is also presented, together with their photochemistry in neat CO matrices.
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Yassine, T. "The hot atom chemistry of some metal complexes and its application to radio isotope production." Thesis, University of Salford, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.381739.
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King, Evan. "Metal-Ligand Multiple Bonds in High-Spin Complexes." Thesis, Harvard University, 2012. http://dissertations.umi.com/gsas.harvard:10356.
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The chemistry of late first row transition metals supported by dipyrromethane and dipyrromethene ligands bearing sterically bulky substituents was explored. Transition metal complexes (Mn, Fe, Co, Ni, Zn) of the dipyrromethane ligand 1,9-dimesityl-5,5-dimethyldipyrromethane (dpma) were prepared. Structural and magnetic characterization (SQUID, EPR) of the bis-pyridine adducts \((dpma)Mn(py)_2\), \((dpma)Fe(py)_2\), and \((dpma)Co(py)_2\) showed each tetrahedral divalent ion to be high-spin, while square planar \((dpma)Ni^{II}(py)_2\) and tetrahedral \((dpma)Zn(py)_2\) were shown to be diamagnetic. Electrochemical experiments revealed oxidative events at common potentials independent of metal identity or spin state, consistent with ligand-based oxidation. Dipyrromethene ligand scaffolds were synthesized bearing large aryl \((Ar = 2,4,6-Ph_{3}C_{6}H_{2}, Mes = 2,4,6-Me_{3}C_{6}H_{2})\) or alkyl \((^{t}Bu = CMe_3, Ad = 1-adamantyl)\) flanking groups to afford three new disubstituted ligands \((^{R}dpme, 1, 9-R_2-5-mesityldipyrromethene, R = Ar, Mes, ^{t}Bu, Ad)\). While high-spin \((S=2)\), four-coordinate iron complexes of the type \((^{R}dpme)FeCl(solv)\) were obtained when R was Mes, tBu, or Ad, use of the sterically encumbered aryl-substituted ligand gave a three-coordinate high-spin \((S=2)\) complex \((^{Ar}dpme)FeCl\). Intramolecular C−H amination was discovered in the reaction of organic azides with \((^{Mes}dpme)FeCl(thf)\), though no intermediate was observed by UV/Vis, IR, or \(^{1}H\) VT-NMR experiments. Reaction of \((^{Ad}dpme)FeCl(OEt_2)\) with alkyl azides resulted in the catalytic amination of C–H bonds or aziridination of olefins at room temperature. Reaction of \(p-^{t}BuC_{6}H_{4}N_{3}\) with \((^{Ar}dpme)FeCl\) permitted isolation of a high-spin \((S=2)\) iron complex \((^{Ar}dpme)FeCl(N(p-^{t}BuC_6H_4))\), featuring a terminal imidyl radical antiferromagnetically coupled to high-spin \(Fe^{III}\), as determined by \(^{1}H\) NMR, X-ray crystallography, and \(^{57}Fe\) Mössbauer. A three-coordinate CoI complex \((^{Ar}dpme)Co(py)\) was synthesized and characterized by \(^{1}H\) NMR, SQUID magnetometry, and X-ray crystallography. Reaction of \((^{Ar}dpme)Co(py)\) with \(^{t}BuN_3\) afforded an isolable three-coordinate Co imide complex \((^{Ar}dpme)Co(N^{t}Bu)\) that exhibits spin crossover from a singlet to a quintet. Reaction of \((^{Ar}dpme)Co(py)\) with mesityl azide produces a spectroscopically observed intermediate, consistent with an \(S=1\) terminal imide complex, that converted via benzylic C–H activation into the metallacycloindoline \((^{Ar}dome)Co(\kappa^{2}-NHC_{6}H_{2}-2,4-Me_{2}-6-CH_2)\).Chemistry and Chemical Biology
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Dioses, Castro Silvio, and Richard Korswagen. "Over the possible role of metal atom clusters in cosmochemistry and in the origin of life." Revista de Química, 2013. http://repositorio.pucp.edu.pe/index/handle/123456789/100714.
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We present here the hypothesis of a possible relationship between metal atom clusters and the formation of organic molecules in the interstellar medium and on small bodies as a possible pathway to the origin of such molecules. Two distinct stages are díscussed: a) the possible formation and presence of atom clusters in space and on the primitive Earth, and b) the synthesis of interstellar and terrestrial prebiotic organic molecules, a process in which metalclusters could be the active catalysts. The confirmatíon of these suggestions might be very important in arder to explain the presence of extra-terrestrial organic molecules in the interstellar medium, small bodies and planetary systems, and therefore would have great relevance in cosmochemistry and in the current theories about the origins of life.
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Ozcan, Gurbetoglu Pelin Gulistan. "Determination Of Cadmium Using Slotted Quartz Tube Atom Trap Atomic Absorption Spectrometry And Metal Coatings." Master's thesis, METU, 2010. http://etd.lib.metu.edu.tr/upload/12612212/index.pdf.
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ABSTRACT
DETERMINATION OF CADMIUM USING SLOTTED QUARTZ TUBE ATOM TRAP ATOMIC ABSORPTION SPECTROMETRY AND METAL COATINGS
Özcan Gurbetoglu, G. Pelin M.S., Department of Chemistry Supervisor: Prof. Dr. O. Yavuz Ataman July 2010, 76 pages Flame atomic absorption spectroscopy (FAAS) is a common technique for detecting metals and metalloids in environmental, biological and metallurgical samples. Although it is a rather old technique, it is still very reliable, simple to use and inexpensive. The technique can be used to determine the concentration of over 70 different metals in a solution. However, it has detection limits at mg/L levels. Some atom trapping methods have been developed to reach the detection limits of ng/mL levels. Slotted quartz tube (SQT) is one of these atom trapping methods. It is an important technique, since it is easy to use, applicable in all laboratories, commercially available and economical. This thesis consists of development of a sensitive method for cadmium with the help of SQT atom trap. In this study, it was used for two different purposes. One was for keeping the analyte atoms more in the light path
in other words, for increasing the residence times of analyte atoms in the measurement zone. This first application was provided a 2.9 times enhancement with respect to conventional FAAS. Second application was for trapping the analyte on the surface of the SQT, in other words, for performing on-line preconcentration of cadmium in SQT. In the presence of a lean flame, analyte samples were trapped and collected for a few minutes at a low suction rate. After finishing the collection period, analyte atoms were revolatilized with the help of a small volume of (10-50 µ
L) methyl isobutyl ketone (MIBK) and a rapid atomization occurred. This introduction also altered the flame composition momentarily and analyte atoms were released from the surface of the SQT. Application of this method enhanced the sensitivity 2065 times with respect to conventional FAAS. Another approach to this type of atom trapping has been investigated also in this study, which was coating of SQT with some metals having low volatility. Therefore, some transition metals were coated to the surface of SQT and among them zirconium was selected as the best coating material as having the most sensitivity enhancement factor. That is why, rest of the study was performed with the Zr coated SQT. The enhancement was 3368 as compared with FAAS. Cd determination with this method provides LOD value of 8 pg/mL and Co value of 19 pg/mL. In order to see the effect of some other type of elements or ions on determination of cadmium, interference study was done.
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Demirtas, Ilknur. "Lead Determination By Flame Atomic Absorption Spectrometry Using A Slotted Quartz Tube Atom Trap And Metal Coatings." Master's thesis, METU, 2009. http://etd.lib.metu.edu.tr/upload/3/12610794/index.pdf.
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Flame Atomic Absorption Spectrometry (FAAS) still keeps its importance despite the relatively low sensitivitybecause it is a simple and economical technique for determination of metals. In recent years atom traps have been developed to increase the sensitivity of FAAS. Although the detection limit of FAAS is only at the level of mg/L, with the use of atom traps it can reach to ng/mL. Slotted quartz tube (SQT) is one of these atom traps, it is applied for determination of volatile elements
it is economical, commercially available and easy to use. In this study, a sensitive analytical method has been developed for the determination of lead with the help of SQT. Regarding the angle between the two slots of SQT, 120°
and 180°
configurations were used and the results were compared. There were three modes of SQT used. The first application was for providing longer residence time of analyte atoms in the measurement zone
3 fold sensitivity enhancement was observed. The second mode was the usage of SQT for preconcentration of lead atoms. In the presence of a lean air-acetylene flame, analyte atoms were trapped in the inner surface of SQT for a few minutes. Then, by the help of a small volume (10-50 &
#956
L) of Methyl isobutyl ketone (MIBK), analyte atoms were revolatilized and a rapid atomization took place. Using this mode, a sensitivity enhancement of 574 was obtained at a rather low (3.9 mL/min) suction rate
1320 fold improvement was reached at higher sample suction rate (7.4 mL/min) for 5.0 min collection. The last mode involves coating of the inner surface of SQT with several kinds of transition metals. The best sensitivity enhancement, 1650 fold, was obtained by the Ta coated SQT. In addition, effects of some elements and anions on Pb signal in Tacoated-SQT-AT-FAAS were examined. Final step consists of surface analysis
chemical nature of Pb trapped on quartz and Ta surface, and the chemical nature of Ta on quartz surface were investigated by X-ray Photoelectron Spectroscopy (XPS) and Raman Spectroscopy.
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Osmanbasoglu, Mahmut. "Tellurium Determination By Flame Atomic Absorption Spectrometry Using A Slotted Quartz Tube Atom Trap And Metal Coatings." Master's thesis, METU, 2011. http://etd.lib.metu.edu.tr/upload/12613029/index.pdf.
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Flame Atomic Absorption Spectroscopy (FAAS) has lover sensitivity than similar analytical methods, however it has an important place for analysis due to its easy application and economic practicability especially in metal determinations. In order to increase the sensitivity of FAAS from mg/L level to ng/L level, various atom trap systems have been used. One of these atom traps, Slotted Quartz Tube (SQT), which is easy, economical and useful for volatile element determination, is used in this study as a sensitive analytical method for determination of tellurium. In the study, determination of Te by SQT is handled in three different modules. First, only with SQT itself, longer residence time for Te atoms in the measurement zone is provided and consequently 3.2 fold sensitivity enhancement is obtained both for Te (VI) and Te (IV). In the second module, SQT is used for concentration of tellurium species in a lean flame by sending the analyte into SQT for a definite time and trapping them on the inner surface of the SQT. After trapping the analyte, in order to determine the Te concentration, a small volume (10-50 µL) of organic solvent such as methyl ethyl ketone (MEK) is introduced to the flame for revolatilization and a rapid atomization of Te on the surface is provided. In this trapping method, for 5 minutes collection with a 6 mL/min suction rate, 143 fold enhancement for Te (VI) and 142 fold enhancement for Te (IV) were obtained. In the third module, different from the second one, the inner surface of the SQT is coated with different metals for increasing the amount of Te trapped on the surface and the best enhancement for tellurium is obtained with Tantalum-coated SQT with 252 fold enhancement for Te (VI) and 246 fold enhancements for Te (IV). All improvements are calculated according to the signals obtained in FAAS method. Separate calibration plots were used for Te (IV) and Te (VI).
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O'Hare, D. M. "Activation of carbon hydrogen bonds by metal atoms." Thesis, University of Oxford, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.355789.
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English, Jason B. "Electronic structure investigations of multiple bonding between atoms: From metal-nitrogen triple bonds to metal-metal triple and quadruple bonds." Diss., The University of Arizona, 2002. http://hdl.handle.net/10150/280021.
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The nature of multiple bonding involving transition metal atoms has been explored via photoelectron spectroscopic and computational studies of molecules containing metal-metal quadruple and triple bonds as well as of molecules containing formal metal-nitrogen triple bonds. The principles governing the nature of the multiple bonding in these systems are similar whether the multiple bonding occurs between two transition metals or between a transition metal and a nitrogen atom. First, the electronic structures of the R₃M≡N molecules, where R = ᵗBuO (Cr, Mo, W); iPrO (Mo); (CH₃)₂CF₃CO (Mo); and Cl (Mo), are examined by photoelectron spectroscopy in conjunction with density functional calculations. To assign the features seen in the photoelectron spectra, close attention is paid to the effects of (1) metal substitution and (2) alkoxide (or Cl) substitution. Examination of the photoelectron spectra of the full series of alkoxide-substituted molecules allows the relative positions of the ionizations from the M≡N σ and π orbitals to be identified. Of great importance to the electronic structure of these molecules are the alkoxide orbital combinations that mix strongly with the M≡N σ and π orbitals. The importance of the ancillary ligand combinations is clearly demonstrated by the photoelectron spectroscopic and computational studies of Cl₃Mo≡N. The replacement of the alkoxide ligand with chlorides greatly simplifies the resultant photoelectron spectrum, allowing all of the valence ionizations to be assigned. Next, the bonding in the M₂X₄(PMe₃)₄ molecules, where M = Mo (X = Cl, Br); W (X = Cl); and Re (X = Cl, Br, I), is explored by photoelectron spectroscopic investigations in conjunction with electronic structure calculations. From these investigations, the ionizations from the metal-based orbitals as well as several ligand-based orbitals have been assigned. The first ionization energies of both the molybdenum (δ) and rhenium (δ*) molecules decrease as the electronegativity of the halide increases. The origin of this inverse halide effect is explored. Finally, the nature of the quadruple metal-metal bond in the M₂(chp)₄ molecules (M = Cr, Mo, W; chp = 2-chloro-6-oxo-pyridinate) is probed. For all three metal systems, an ionization from the M₂ δ orbital can be seen. This is only the second time a distinct ionization feature has been noted for ionization of the delta orbital from a dichromium molecule. Comparisons with the previously studied M₂(mhp)₄ molecules (mhp = 6-methyl-2-oxo-pyridinate) allow for a better understanding of the electronic structure of these molecules.
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Loades, Stephen David. "Bonding to transition metal atoms in low oxidation states." Thesis, University of Liverpool, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.333641.
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Williams, Christina Joyce. "An ESR study of metal atoms and organometallic compounds of biological interest." Thesis, Liverpool John Moores University, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.484223.
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Subramaniam, Kavitha. "Metal uptake and its effects on colloidal particle interactions : equilibria and rates." Diss., Georgia Institute of Technology, 2000. http://hdl.handle.net/1853/20206.
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So, Eric. "Interaction of Rydberg hydrogen atoms with metal surfaces." Thesis, University of Oxford, 2011. http://ora.ox.ac.uk/objects/uuid:53984973-1766-45cc-8bcf-055be714ed73.
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This thesis presents a theoretical and experimental investigation of the interaction of electronically excited Rydberg hydrogen atoms with metal surfaces and the associated charge-transfer process. As a Rydberg atom approaches a metal surface, the energies of the Rydberg states are perturbed by the surface potential generated by the image charges of the Rydberg electron and core. At small atom-surface separations, the Rydberg atom may be ionised by resonant charge transfer of the Rydberg electron to the continuum of delocalised unoccupied metal states, with which the Rydberg electron is degenerate in energy. Typically, this ‘surface ionisation’ can be measured by extracting the remaining positively charged ion-cores with externally applied electric fields. By applying various levels of theory, from classical to fully time-dependent quantum calculations, this thesis explores various experimentally relevant effects on the charge-transfer process, such as the magnitude and direction of the externally applied electric field, the atom collisional velocity, the presence of local surface stray fields and electronically structured surfaces. The theoretical results give insight into the previous experimental work carried out for the xenon atom and hydrogen molecule, and point out some of the fundamental differences from the hydrogen atom system. Experiments involving Rydberg hydrogen atoms incident on an atomically flat gold surface, a rough machined aluminium surface and a single crystal copper (100) surface are presented, providing for the first time the opportunity to make a quantitative comparison of theory and experiments. The ability to control the critical distance at which charge-transfer occurs is demonstrated by using Rydberg states of varying dimensions and collisional velocities. By changing the collisional angle of the incident Rydberg beam, the effect of Rydberg trajectory is also investigated. By manipulating the polarisation of the Rydberg electron with electric fields, genuine control over the orientation of the electron density distribution in the charge-transfer process is demonstrated. This property was predicted by the theory and should be unique to the hydrogen atom due to its intrinsic symmetry. By reversing the direction of the electric field with respect to the metal surface, electrons rather than positive ions are detected, with ionisation dynamics that appear to be very different, as predicted by quantum calculations. Experiments involving the single crystal Cu(100) surface also suggests possible resonance effects from image states embedded in the projected bandgap which are shown from quantum calculations to play an important role in the surface charge transfer of electronically structured metal substrates. The experimental technique developed in this work provides some exciting future applications to study quantum confinement effects with thin films, nanoparticles and other bandgap surfaces. The ability to control the Rydberg orbital size, electronic energy, collisional velocity and orientation in the charge-transfer process will provide novel ways of probing the surface’s electronic and physical structure, as well as being a valuable feature in offering new opportunities for controlling reactive processes at metallic surfaces.
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Mulley, Suzanne M. "Physical studies of interstitial atoms in transition metal clusters by electron microscopy and N.M.R. spectroscopy." Thesis, University of Liverpool, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.316607.
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Meng, Yao. "Hydrogen electrochemistry in room temperature ionic liquids." Thesis, University of Oxford, 2012. http://ora.ox.ac.uk/objects/uuid:be24c6ea-c351-4855-ad9c-98e747ac87e4.
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This thesis primarily focuses on the electrochemical properties of the H2/H+ redox couple, at various metallic electrodes in room temperature ionic liquids. Initially, a comprehensive overview of room temperature ionic liquids, RTILs, compared to conventional organic solvents is presented which identifies their favourable properties and applications, followed by a second chapter describing the basic theory of electrochemistry. A third chapter presents the general experimental reagents, instruments and measurements used in this thesis. The results presented in this thesis are summarized in six further chapters and shown as follows. (1) Hydrogenolysis, hydrogen loaded palladium electrodes by electrolysis of H[NTf2] in a RTIL [C2mim][NTf2]. (2) Palladium nanoparticle-modified carbon nanotubes for electrochemical hydrogenolysis in RTILs. (3) Electrochemistry of hydrogen in the RTIL [C2mim][NTf2]: dissolved hydrogen lubricates diffusional transport. (4) The hydrogen evolution reaction in a room temperature ionic liquid: mechanism and electrocatalyst trends. (5) The formal potentials and electrode kinetics of the proton_hydrogen couple in various room temperature ionic liquids. (6) The electroreduction of benzoic acid: voltammetric observation of adsorbed hydrogen at a Platinum microelectrode in room temperature ionic liquids. The first two studies show electrochemically formed adsorbed H atoms at a metallic Pt or Pd surface can be used for clean, efficient, safe electrochemical hydrogenolysis of organic compounds in RTIL media. The next study shows the physicochemical changes of RTIL properties, arising from dissolved hydrogen gas. The last three studies looked at the electrochemical properties of H2/H+ redox couple at various metallic electrodes over a range of RTILs vs a stable Ag/Ag+ reference couple, using H[NTf2] and benzoic acid as proton sources. The kinetic and thermodynamic mechanisms of some reactions or processes are the same in RTILs as in conventional organic or aqueous solvents, but other remarkably different behaviours are presented. Most importantly significant constants are seen for platinum, gold and molybdenum electrodes in term of the mechanism of proton reduction to form hydrogen.
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Rydén, Jens Olof Stefan. "Computational studies Of manganese-ligand clusters in the gas-phase and manganese atoms in graphene and metal-organic frameworks." Thesis, University of Sussex, 2011. http://sro.sussex.ac.uk/id/eprint/7400/.
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The work in this thesis deals with computational studies of manganese ions and atoms in the gas-phase and in the solid phase. The results are divided into three chapters, and the theory and methods used are explained and discussed in a separate theory chapter. The first results on manganese and its coordination to water and methanol molecules in the gas-phase are discussed in the light of physical properties for different ligands including water and methanol. Preferred coordination of a specific ligand type, preferred complex or cluster size as well as coordination modes are thoroughly investigated. Also discussed is stability against proton-transfer reactions for a few manganese-water and manganese-methanol clusters. The work is carried out at the HF/6- 31G(d), MP2/6-311G(d,p) and B3LYP/6-311(3df,3pd)-level of theory using the computer code Gaussian. The results presented here are in good agreement with experimental results and findings. It is concluded that mixing between 4s and 3d orbitals on the manganese atom is responsible for preference for a specific cluster size and that occupation of anti-bonding orbitals destabilizes the cluster, for a specific coordination mode. The next results are for manganese atoms in a double layer of graphite, using the computer code Aimpro. Different coordination modes are investigated as are magnetic properties upon adsorption and modification of the band structure compared to a pristine double layer of graphene. Only one case of a significantly high spin polarization is encountered, and the spin polarization on the manganese atom and the surrounding carbon atoms is investigated with Mulliken analysis. This study is in agreement with previous work in the same field, but provides a more realistic picture since a larger system is considered here. The final chapter deals with manganese atoms in metal-organic frameworks, MOFs, using the Aimpro code. Magnetic properties and binding energies for adsorption of selected molecules are discussed in this chapter. Magnetic properties are discussed using Mulliken analysis. Modification of the band structure upon coordination of these gas molecules is shown and investigated. Very few experimental results exist in this field for this structure, but its role as a potential candidate for hydrogen storage will specifically be discussed.
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Netzell, Elisabeth. "Using models and representations in learning and teaching about the atom : A systematic literature review." Thesis, Linköpings universitet, Institutionen för fysik, kemi och biologi, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-117163.
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This study is a systematic literature review on the role of models and representations in the teaching, learning and understanding of the atom and atomic concepts. The aim of the study is to investigate the role of different visual representations, what models and representations are used in the science classroom, how learners interpret different external representations of the atom, what mental models students construct, and how the representations can be used and designed for meaningful learning and teaching of the atom and atomic concepts. In this systematic literature review, a combination of different databases was used to search for literature, namely ERIC, Scopus and Google Scholar. Some limiters were used to narrow down the returned results: the articles should be peer-reviewed and be published 1990-01-01 or later. Ten of the returned articles were included for individual analysis in the study. The results of the study show that students often find concepts of atomic structure difficult and confusing. The abstract microscopic world of atoms cannot be seen with the naked eye, and models are therefore necessary and crucial educational tools for teaching atomic concepts in school. However, when using a model, it is important for the teacher to explain the rules of the model, and the advantages and limitations of the representation must be discussed. Analysis of the included articles revealed three types of representations used to represent atomic phenomena: two-dimensional static diagrams or pictures (e.g. a picture of the atom), three-dimensional videos or simulations (e.g. virtual reality simulations), and visual analogies (e.g. the Bohr planetary model of the atom). The use of simulations and interactive learning environments seem to have a positive effect on students’ learning. One of the studies, described in the articles included for analysis, showed that students appreciated the use of virtual reality simulations, since it made abstract concepts easier to understand when they could be visualized.
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Netzell, Elisabeth. "What models and representations do Swedish upper secondary school teachers use in their teaching about the atom?" Thesis, Linköpings universitet, Institutionen för fysik, kemi och biologi, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-131625.
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This report presents the results from a survey study on Swedish upper secondary school physics andchemistry teachers’ use of models and representations in teaching the atom. The study builds upon an earlier systematic international literature review on the role of models and representations in the teaching, learning and understanding of the atom. The overall aim of the study is to explore what models and representations are used by Swedish upper secondary school physics and chemistry teachers in their teaching about the atom, what informs teachers’ selection of the atomic models and representation forms and how they specifically use them in their teaching of the atom. The method for collecting the data for this study was an electronic questionnaire containing six introductory questions followed by nine open and four closed items, which were analysed both quantitatively and qualitatively. Thirty-one responses were received and analysed in this study. The results of the study indicate that Swedish teachers’ selection and use of atomic models and representation forms in their practice correspond with findings in the previously conducted literature review. For example, the Bohr atomic model was shown to be the most popular for teaching about the atom amongst the Swedish teachers in this study, since it is deemed intuitive and easy to visualize. A further result revealed that the de Broglie atomic model was only used by physics teachers, and that physics teachers overall used more atomic models in their teaching than chemistry teachers, a finding that might be related to the different teaching content in physics and chemistry. The study also shows that Swedish teachers are very comfortable with, and advocate, using different representation forms in their teaching. One interesting finding in this regard was that the use of physical models is predominantly more popular among chemistry than physics teachers. In line with the findings in the previous literature review study, students’ prior knowledge and individual learning styles were found tobe important influencing factors in teachers’ selection of representation forms to use in the classroom.The majority of the teachers also agreed on that it is important to explain to students how models should be interpreted and used, but one interesting finding, that differs from the previous research, is that some teachers were of the opinion that students have an already well-developed modelling ability when encountering different models of the atom.
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Awali, Slim. "Dynamique de relaxation électronique d’un atome métallique déposé sur agrégat d’argon." Thesis, Paris 11, 2014. http://www.theses.fr/2014PA112013/document.
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Ce travail de thèse est une recherche sur l'interaction entre des états atomiques excités électroniquement et un environnement non réactif. Nous avons étudié théoriquement et expérimentalement des situations où un atome métallique (K et Ba) est placé dans un environnement de taille finie (agrégat d’argon). La présence de l'environnement affecte les niveaux électroniques de l'atome. En retour, l'excitation de l'atome induit une dynamique de relaxation de l'énergie électronique via les déformations du système atome-agrégat. La partie expérimentale du travail porte sur les deux aspects : spectroscopie et dynamique. Dans les deux cas un premier laser porte l'atome métallique dans un état électronique excité et un second l'ionise. L'observable est le spectre de photoélectrons enregistré après photo ionisation éventuellement complétée par des informations sur les photo-ions qui sont également produits. Cette technique à deux lasers conduit à des mesures de dynamique selon la technique pompe-sonde quand les lasers utilisés sont à impulsion ultracourte (60 fs). L'utilisation de lasers nanosecondes, conduit à des mesures de résonance non résolues temporellement qui donnent des informations spectroscopiques sur la position des niveaux d'énergie du système étudié. D’un point de vue théorique, les états excités du système M-Ar_n ont été calculés ab-initio en utilisant des pseudo-potentiels à grand cœur pour limiter les électrons actifs aux seuls électrons de valence du métal. L’étude d’un métal alcalin (potassium) rend cette méthode particulièrement attractive car un seul électron est actif. Le calcul ab-initio et une simulation Monte-Carlo ont été couplés pour optimiser la géométrie d'agrégats KAr_n (n=1-10) quand K est dans l'état fondamental, excité dans les états 4p ou 5s ou ionisé vers l'état fondamental de l'ion. Des calculs ont également été conduits en collaboration avec B. Gervais (CIMAP, Caen) sur des agrégats KAr_n comportant plusieurs dizaines d'atomes Ar. Des spectres d'absorption ont également été calculés. D’un point de vue expérimental, nous avons pu caractériser les niveaux électroniques excités du potassium et du baryum perturbés par l’agrégat. Dans les deux cas une bande ∏, liante, et une bande ∑, anti-liante, ont été observées. Dans le cas du potassium, nous avons montré que l’excitation dans la bande ∑ conduisait à une éjection de l’agrégat en 1-2 ps alors que pour le baryum, l’état électronique relaxe majoritairement sur l’état ∏ en ≈ 6 ps et ne conduit pas à une éjection. L’interprétation fait appel aux structures et aux potentiels calculés. Une étude équivalente a été conduite sur la molécule de DABCO déposée sur agrégat. Au contraire de K et Ba, le premier état excité de cette molécule a un fort caractère isotrope et diffus, ce qui confère un caractère particulier à la dynamique photoinduiteThis thesis is a study on the interaction between electronically excited atomic states and a non-reactive environment. We have theoretically and experimentally studied situations where a metal atom (Ba or K) is placed in a finite size environment (argon cluster). The presence of the medium affects the electronic levels of the atom. On the other side, the excitation of the atom induces a relaxation dynamics of the electronic energy through the deformation of the cluster. The experimental part of this work focuses on two aspects : the spectroscopy and the dynamics. In both cases a first laser electronically excites the metal atom and the second ionizes the excited system. The observable is the photoelectron spectrum recorded after photoionization and possibly information on the photoion which are also produced. This pump/probe technique, with also two lasers, provide the ultrafast dynamic when the lasers pulses used are of ultrashort (60 fs ). The use of nanosecond lasers leads to resonance spectroscopic measurement, unresolved temporally, which give information on the position of the energy levels of the studied system. From a theoretical point-of-view, the excited states of M-Ar_n were calculated at the ab initio level, using large core pseudo-potential to limit the active electrons of the metal to valence electrons. The study of alkali metals (potassium) is especially well adapted to this method since only one electron is active. The ab-initio calculation and a Monte-Carlo simulation where coupled to optimize the geometry of the KAr_n (n = 1-10) cluster when K is in the ground state of the neutral and the ion, or excited in the 4p or 5s state. Calculations were also conducted in collaboration with B. Gervais (CIMAP, Caen) on KAr_n clusters having several tens of argon atoms. Absorption spectra were also calculated. From an experimental point-of-view, we were able to characterize the excited states of potassium and barium perturbed by the clusters. In both cases a binding ∏-state, and an anti-binding ∑ -state were observed. In the case of potassium, we observered that the excitation on the ∑ -state leads to the ejection of the metal within 1-2 ps while for barium, the excited state relaxes mainly on the ∏-state within 6 ps and does not followed by an ejection. The interpretation of these results uses the structures and potential calculated. A similar study was conducted on the DABCO molecule deposited argon cluster. Instead of K and Ba, the first excited state of this molecule is a diffuse isotropic state, which gives a specific relaxation to the photoinduced dynamics
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Norberg, Daniel. "Quantum Chemical Studies of Radical Cation Rearrangement, Radical Carbonylation, and Homolytic Substitution Reactions." Doctoral thesis, Uppsala : Acta Universitatis Upsaliensis, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-8178.
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Estes, Deven Paul. "Transition Metal Hydrides that Mediate Catalytic Hydrogen Atom Transfers." Thesis, 2014. https://doi.org/10.7916/D8SF2TDQ.
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Radical cyclizations are important reactions in organic chemistry. However, they are seldom used industrially due to their reliance on neurotoxic trialkyltin hydride. Many substitutes for tin hydrides have been developed but none have provided a general solution to the problem.
Transition metal hydrides with weak M-H bonds can generate carbon centered radicals by hydrogen atom transfer (HAT) to olefins. This metal to olefin hydrogen atom transfer (MOHAT) reaction has been postulated as the initial step in many hydrogenation and hydroformylation reactions. The Norton group has shown MOHAT can mediate radical cyclizations of ɑ,ω dienes to form five and six membered rings. The reaction can be done catalytically if 1) the product metalloradical reacts with hydrogen gas to reform the hydride and 2) the hydride can perform MOHAT reactions. The Norton group has shown that both CpCr(CO)₃H and Co(dmgBF₂)₂(H₂O)₂ can catalyze radical cyclizations. However, both have significant draw backs.
In an effort to improve the catalytic efficiency of these reactions we have studied several potential catalyst candidates to test their viability as radical cyclization catalysts. I investigate the hydride CpFe(CO)₂H (FpH). FpH has been shown to transfer hydrogen atoms to dienes and styrenes. I measured the Fe-H bond dissociation free energy (BDFE) to be 63 kcal/mol (much higher than previously thought) and showed that this hydride is not a good candidate for catalytic radical cyclizations.
I have investigated the dynamics of Co(dmgBF₂)₂(H₂O)₂ under hydrogen gas to attempt to observe its hypothesized cobalt hydride. Under large pressures up to 70 atm we see two species one which we assign as the cobalt hydride and one which we assign as a ligand protonated Co(I) complex. These are supported by high pressure NMR studies of the same complexes. By varying the H₂ pressure, we can calculate the hydrogen atom donor ability of the mixture formed under H₂ as 50 kcal/mol. This makes this mixture a very good H• donor.
The Norton group has shown that vanadium hydrides have very weak V-H bonds that donate H* rapidly. However, they cannot be made catalytic under hydrogen gas. I have attempted to regenerate these vanadium hydrides by a sequential reduction then protonation of the metalloradical. With HV(CO)₄dppe this only produced hydrogen gas, presumably by one electron reduction of HV(CO)₄dppe. However, with HV(CO)₄dppf this does not readily occur and this hydride could potentially be a catalyst for radical cyclizations.
Many radical cyclizations involve vinyl (sp²) radicals. I have shown that both the CpCr(CO)₃H and the Co(dmgBF₂)₂(H₂O)₂ systems can catalytically perform metal to alkyne hydrogen atom transfers (MAHAT's) and that these reactions can be used to perform radical cyclizations very efficiently.
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Kuo, Jonathan Lan. "Using First Row Transition Metal Hydrides as Hydrogen Atom Donors." Thesis, 2017. https://doi.org/10.7916/D8MG8226.
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Radical cyclizations have become a mainstay of synthetic organic chemistry – useful for the construction of C–C bonds in laboratory-scale applications. However, they are seldom used the industrial scale. In large part, this is because of a reliance on Bu3SnH, widely regarded as the best synthetic equivalent to a hydrogen atom.
Transition metal hydrides have emerged as promising alternative hydrogen atom sources. Over the last decade, the Norton group has studied three transition metal systems, with an emphasis on quantifying the M–H bond dissociation energies. Over time, the group has shown that, thermodynamically, first-row transition metal hydrides are good hydrogen atom donors; they often have weak M–H bonds. Modest adjustments to the M–H bond strength result in substantial changes to how a hydride processes a given organic substrate.
The Norton group has also studied the kinetics of hydrogen atom transfer, and shown that transition metal hydrides are kinetically competent at transferring hydrogen atoms, both to olefinic substrates and to organic radicals. Some of the transition metal complexes are made catalytic under modest pressures of H2, so they can be used for effecting atom-economical radical reactions.
I have leveraged the fundamental kinetic and thermodynamic information that has been gathered by the group to develop new radical reactions – ones that cannot be done by Bu3SnH. Herein are described two cases studies: the first is the generation of α-alkoxy radicals by hydrogen atom transfer to enol ethers (Chapter 2). The second is the development of a radical isomerization and cycloisomerization reactions (Chapter 3). Both of these developments have relied upon an understanding of M–H thermochemistry.
Discovering new hydrogen atom donors will lead to discovering new radical reactions. In Chapter 4, I revisit two previously reported transition metal hydrides that are likely to transfer hydrogen atoms: (TMS3tren)CrIV–H and [CpV(CO)3H]–. Although the anionic vanadium hydride was reported as a potent hydrogen atom donor nearly forty years ago, my studies suggest that its M–H bond is actually relatively strong. I have therefore reevaluated the reactivity of [CpV(CO)3H]–, and found that although the 18 electron anionic hydride is not a good hydrogen atom donor, the oxidized 17-electron neutral CpV(CO)3H is an extremely potent one. I have made the reactions with [CpV(CO)3H]– catalytic under H2 (now the reactions are done with an added base). The catalytic reactions that use [CpV(CO)3H]– can enact the exact same transformations that tin does, so I have developed a true catalytic replacement for Bu3SnH.
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Li, Gang. "Transition-Metal Complexes Catalyzed Hydrogen Atom Transfer: Kinetic Study and Applications to Radical Cyclizations." Thesis, 2015. https://doi.org/10.7916/D88S4P7C.
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Radical cyclizations have been proven to be extremely important in organic synthesis. However, their reliance on toxic trialkyltin hydrides has precluded their practical applications in pharmaceutical manufacturing. Many tin hydride substitutes have been suggested but none of them are adequate alternates to the traditional tin reagent.
Transition-metal hydrides have been shown to catalyze the hydrogenation and hydroformylation of unsaturated carbon-carbon bonds. Theses reactions begin with a Hydrogen Atom Transfer (HAT) from a metal to an olefin, generating a carbon-centered radical. The cyclization of that radical is an effective route to five- and six-membered rings. The HAT will be fastest if the M–H bond is weak. However, making the reaction catalytic will require that the hydride can be regenerated with H2. HCr(CO)3Cp has proven to be a good catalyst for such cyclizations, but it suffers from air sensitivity. The yield of the cyclization product depends on how the rate of radical cyclization compares with the rates of side reactions (hydrogenation and isomerization), so special substituents on a substrate are best installed to increase the cyclization rate.
In attempting to improve the efficiency of radical cyclization I have studied the effect of substituents on the target double bond on the rate of cyclization. A single phenyl substituent has proven to stabilize a radical better than two phenyls. This stabilization leads to faster cyclizations and a higher cyclization yield.
I also have found that Co(dmgBF2)L2 (L = THF, H2O, MeOH…) under H2 is an effective hydrogen atom donor. I have monitored by NMR the catalysis by the system of the hydrogenation of stable radicals (trityl radical and TEMPO radical) and found the rate-determining step to be the activation of hydrogen gas by CoII. The reactive form of the complex is five-coordinated cobalt complex Co(dmgBF2)2L.
The Co/H2 system can also transfer hydrogen atom to C=C bonds, thus initiate radical cyclizations. The resting state of the cobalt is the CoII metalloradical, so a cycloisomerization is obtained. Such a reaction neither loses nor adds any atom and has 100% atom economy.
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Bhaskar, Srilakshmi P. "A Study on Digestive Ripening Mediated Size and Structure Control in Nanoparticles Prepared by Solvated Metal Atom Dispersion Method." Thesis, 2016. http://hdl.handle.net/2005/2924.
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Recent advancements in nanotechnology and emerging applications of nanomaterials in various fields have stimulated interest in fundamental scientific research dealing with the size and structure controlled synthesis of nanoparticles. The unique properties of nanoparticles are largely size dependent which could be tuned further by varying shape, structure, and surface properties, etc. The preparation of monodisperse nanoparticles is desirable for many applications due to better control over properties and higher performance compared to polydispersity nanoparticles. There are several methods for the synthesis of nanoparticles based on top-down and bottom-up approaches. The main disadvantage of top-down approach is the difficulty in achieving size control. Whereas, uniform nanoparticles with controllable size could be obtained by chemical methods but most of them are difficult to scale up. Moreover, a separate step of size separation is necessary in order to achieve monodispersed which may lead to material loss. In this context, a post-synthetic size modification process known as digestive ripening is highly significant. In this process, addition of a capping agent to poly disperse colloid renders it highly monodisperse either under ambient or thermal conditions. In addition to size control, digestive ripening is also effective in controlling the structure of nanoparticles in colloidal solution comprising two different elements. Use of co-digestive ripening strategy in conjunction with solvated metal atom dispersion (SMAD) method of synthesis resulted in hetero structures such as core–shell,
alloy, and composite nanoparticles. Despite the versatility of digestive ripening process, the underlying mechanism in controlling size and structure of nanoparticles are not understood to date. The aim of this thesis is to gain mechanistic insight into size control of digestive ripening as well as to investigate structure control in various binary systems.
Objectives
Study digestive ripening of Au nanoparticles using various alkyl amines to probe the mechanism
Study co-digestive ripening of binary colloids consisting of two metals, Pd and Cu prepared separately by SMAD method
Study co-digestive ripening of binary colloids consisting of a metal (Au) and a semiconductor (CdS) prepared separately by SMAD method
Study vaporization of bulk brass in SMAD reactor and analyse phase, structure, and morphology of various Cu/Zn bimetallic nanoparticles obtained from bulk brass under various experimental conditions
Significant results
In chapter 1, fundamental processes of nanoparticle formation and common synthetic techniques for the preparation of monodisperse nanoparticles are briefly discussed. Chapter 2 presents a mechanistic study of digestive ripening process with regard to size control using Au nanoparticles as a model system. Three long chain alkyl amine molecules having different chain length were used as digestive ripening agents. The course of digestive ripening process was analysed by UV-visible spectroscopy and transmission electron microscopy. The experimental conditions such as concentration of digestive ripening agent, time, and temperature were found to influence the size distribution of nanoparticles. The average particle size was found to be characteristic of metal-digestive ripening agent combination which is considered as the optimum size preferred during digestive ripening under a given set of experimental conditions. This study discusses stabilization of optimum sized particles, surface etching, and reversibility in digestive ripening.
Chapter 3 describes the synthesis and characterization of PdCu alloy nanoparticles by co-digestive ripening method. Syntheses of individual Pd and Cu colloids were carried out by SMAD method. Pd nanoparticles obtained using THF as solvent and in the absence of any capping agent resulted in an extended small Pd nanowire network assembly. Morphological evolution of spherical Pd nanoparticles from Pd nanowire network structure was observed with the use of capping agent, hexadecyl amine (HDA) in SMAD method. Co-digestive ripening of Pd and Cu colloids was studied at various temperatures. This study revealed temperature dependent diffusion of Cu atoms into Pd lattice forming PdCu alloy nanoparticles.
Next, co-digestive ripening of a colloidal system comprising a metal and a semiconductor was explored. Au-CdS combination was chosen for this study owing to its interesting photocatalytic properties. Chapter 4 deals with the synthesis of Au and CdS nanoparticles by SMAD method and Au/CdS nanocomposite by co-digestive ripening. CdS nanoparticles of size 4.0 + 1.2 nm and Au nanoparticles of size 5.6 + 1.1 nm were obtained as a result of digestive ripening process. Au/CdS nanocomposite obtained by co-digestive ripening was characterized by a matrix-like structure made up of CdS nanoparticles in which Au nanoparticles were embedded. CdS nanoparticles were found to establish an intimate surface contact with Au nanoparticles and the matrix of CdS surrounding Au was developed via aggregation during digestive ripening.
Chapter 5 describes a comprehensive study on various Cu/Zn bimetallic nanoparticles obtained from bulk brass. Vaporization of bulk brass in SMAD reactor led to a deploying
process and further growth of nanoparticles from phase separated Cu and Zn atoms formed a composite structure. The characterization of Cu/Zn nanocomposite revealed covering of composite surface with Cu resulting in a core-shell structure, Cu/Zn@Cu. Post-synthetic digestive ripening of these core-shell composite particles showed diffusion of Zn atoms to the composite surface in addition to size and shape modification. Annealing of Cu/Zn nanocomposites prepared in THF resulted in α-CuZn alloy nanoparticles via sequential transformation through η-CuZn5, γ-Cu5Zn8, and β-CuZn (observed as marten site) phases.
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Jose, Deepa. "Synthesis, Characterization, and Reactivity Studies of Au, Ag, and Pd Colloids Prepared by the Solvated Metal Atom Dispersion (SMAD) Method." Thesis, 2009. http://etd.iisc.ernet.in/2005/3895.
Full textAbstract:
Surfactant bound stable colloids of Au, Ag, and Pd were prepared by the solvated Metal Atom Dispersion (SMAD) method, a method involving co-condensation of metal and solvent vapors on the walls of a reactor at 77 k. The as=prepared dodecanethiol-capped Au and Ag colloids consisting of polydisperse nanoparticles were transformed into colloids consisting of highly monodisperse nanoparticles by the digestive ripening process. In the case of Pd colloids, digestive ripening led to the formation of thiolate complexes. The [Pd(SC12H25)2]6 complex formed from the dodecanethiol-capped Pd nanoparticles was found to be a versatile precursor for the synthesis of a variety of Pd nanophases such as Pd(0), PdS, and Pd@PdO by soventless thermolysis. Co-digestive ripening of as-prepared dodecanethiol-capped Au or Ag colloids with Pd colloid resulted in Au@Pd and Ag@Pd core-shell nanoparticles, respectively; attempts to transform the core-shell structures into alloy phases even at high temperatures were unsuccessful.
Phosphine-capped Au nanoparticles were also prepared by the SMAD method and refluxing of this colloid resulted in an Ostwald ripening process rather than the expected digestive ripening due to the labile nature of bound PPh3. The labile nature of the bound phosphine was studied using 31P NMR spectroscopy and utilized in the adsorption of CO.
Palladium nanoparticles obtained from the SMAD Pd-butanone colloids and Pd@PdO nanoparticles prepared by the solventless thermolysis of Pd-dodecanethiolate complex were found to be good catalysts for the generation of H2 from AB via either hydrolysis and methanolysis. The active hydrogen atoms produced during the hydrolysis and methanolysis diffuse into the Pd lattice. It was also noticed that hydrogen atoms that were buried deep inside the Pd lattice cannot be removed completely by heating the sample even at 600°C. Wet chemical reduction method was employed for the synthesis of PVP capped, nearly monodisperse, spherical Ir nanoparticles which undergo a polymer driven self-assembly at 80°C to afford rectangular structures and interlinked particles.
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Isa, Nabil Saba. "Atom scattering and reactions with self-assembled decanethiol monolayers /." 2003. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pqdiss&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&rft_dat=xri:pqdiss:3097117.
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Martincigh, Bice Susan. "The influence of primary and secondary nitrogen donor atoms on the thermodynamics of complex formation in aqueous solution." Thesis, 1987. http://hdl.handle.net/10413/11368.
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CHIN, ROBERT C. "SPECTROSCOPIC STUDIES OF ALKALI METAL ATOMS ISOLATED IN LOW TEMPERATURE MATRICES; LASER-INDUCED FLUORESCENCE STUDIES OF BIOLOGICAL TISSUES." Thesis, 1987. http://hdl.handle.net/1911/16045.
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The interpretation of absorption spectra of metal atoms isolated in rare gas matrices has long been debated. In our studies we have observed the UV/Vis spectra of lithium/xenon and sodium/xenon matrices. A model is proposed to interpret our results. This model employs a BEBO explanation of the interactions of the metal atom in the rare gas crystal. By establishing the interaction potentials of the metal atom in the crystal, it is possible to calculate overlap integrals and thereby calculate an absorption envelope of Franck-Condon factor sticks. An analytical lineshape for the phonon vibrational wing and the zero phonon line was employed to calculate a theoretical spectrum. This model may be employed in the understanding of impurity atoms in solid rate gas matrices.
The second topic involves the employment of laser radiation as a diagnostic tool in the discrimination of diseased and normal tissues. Laser excitation by an Argon ion laser produced characteristic autofluorescences between malignant and normal lung tissues. Three emission bands in the range of 22000 to 12000 cm$\sp{-1}$ were observed. By applying statistical analysis it is established that the method may be utilized to diagnose malignant tumors in and around the lung. Other tissues studied were atherosclerotic and normal coronary arteries. These tissue types also showed a very characteristic autofluorescence signature. This distinction may be utilized to determine the extent of disease in coronary arteries.
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Chandrappa, G. T. "Studies on the complexes of transition metals with organic compounds containing Nitrogen, Sulphur and Oxygen atoms." Thesis, 1987. http://hdl.handle.net/2009/2623.
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SCHMIDT, HOWARD KHAN. "AUGER ELECTRON SPECTROSCOPY OF CRYOGENIC MATRIX ISOLATED METAL ATOMS AND DIRECT RECOIL SPECTROSCOPY (DRS), SIMS AND XPS STUDIES ON TITANIUM AND PIQ." Thesis, 1987. http://hdl.handle.net/1911/19059.
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Auger electron spectra of matrix-isolated metal atoms have been recorded for the first time. Differences in extra-atomic relaxation between bulk metal and argon matrix isolated atoms resulted in shifts in the energy of LMM Auger electrons, $-3.1$ eV for potassium and $-8.7$ eV for titanium. The sum of the shift and the known difference between the energies of LMM Auger electrons from gaseous and frozen argon is a good estimate of the total extra-atomic relaxation energy for the bulk metal after Auger processes.
Polyimide Isoindolo Quinazolin-dione (PIQ) was studied in detail with Direct Recoil Spectroscopy (DRS), X-ray Photoelectron Spectroscopy (XPS) and Secondary Ion Mass Spectroscopy (SIMS) to determine the effects of argon and nitrogen ion implantation, oxygen recoil implantation, and vacuum annealing. A hydrocarbon contaminant that cannot be detected by XPS alone was confirmed to exist with DRS. Ion bombardment, even at relatively low energies, causes profound graphitization of the surface. DRS and XPS data show that appreciable amounts of nitrogen and oxygen can be implanted into the polymer, and that the implanted species are stable up to 300$\sp\circ$C. DRS evidence suggests that water dissociates on the 3 keV argon ion bombarded PIQ surface, adding hydrogen to the surface but not oxygen. DRS, XPS and SIMS have been used to examine chemisorption and annealing on polycrystalline titanium. Dynamic surface processes were studied with DRS on the time-scale of 30 seconds, revealing that a surface phase transition takes place on Ar$\sp{+}$ sputtered titanium at only 500$\sp\circ$K.
DRS in conjunction with XPS showed conclusive evidence for formation of a subsurface nitride after a nitride titanium sample was exposed to oxygen. A 'trickle down' mechanism is proposed to account for the formation of the subsurface species. There are at least two surface sites for hydrogen, nitrogen and oxygen. At room temperature, the hydrogens' lower site is saturated, even after sputter-cleaning.