Dissertations / Theses on the topic 'Alkali metal'
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1
Chen, Jian. "Alkali metal cluster theory." Thesis, University of Oxford, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.305984.
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Robinson, Alex Lockwood. "Sonoluminescence for the quantitative analysis of alkali and alkaline earth chlorides /." Thesis, Connect to this title online; UW restricted, 2001. http://hdl.handle.net/1773/8687.
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Jones, Sally Anne. "Alkali and alkaline earth metal fluoride mediated aromoatic halogen exchange reactions." Thesis, University of Liverpool, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.367085.
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Allen, Katharine M. "Intercalation chemistry of alkali metal fullerides." Thesis, University of Oxford, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.390457.
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Witherow, Rebecca A. "Minor Alkaline Earth Element and Alkali Metal Behavior in Closed-Basin Lakes." The Ohio State University, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=osu1250628213.
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Salter, Tom E. "Infrared spectroscopy of alkali metal-solvent clusters." Thesis, University of Leicester, 2007. http://hdl.handle.net/2381/29997.
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Infrared (IR) photodepletion spectroscopy coupled with mass spectrometry has been applied in the investigation of size-specific alkali metal-solute complexes. IR spectra have been recorded in the N-H stretching region for Li(NH3)n (4 = n = 7) and Na(NH3)n (3 = n = 8) and in the N-H and C-H stretching regions for Li(NH2CH 3)n (3 = n = 5), with supporting ab initio calculations. All clusters display a red-shift of the N-H stretching modes, consistent with partial electron transfer from the nitrogen to the alkali metal atom. For Li(NH3)n, the IR spectra indicate that the first salvation shell is found to be completed with four ammonia molecules, which is in agreement with conclusions drawn from previous photoionisation studies. This finding is given credence from DFT and MP2 ab initio calculations carried out in the present work, where the lowest energy isomer for n = 4 is adopts a tetrahedral structure. The IR spectra for Na(NH3)n clusters are less definitive, but indicate a completed inner salvation shell with six ammonia molecules, a conclusion in disagreement with some previous experimental and theoretical investigations, but which is consistent with high-level ab initio calculations carried out in the present study. Ab initio investigations into the localisation of the alkali metal valence electron in the three systems determined that not only are a critical number of solvent molecule required to permit formation of a solvated electron, but also a specific geometrical configuration is required. For lithium-ammonia and sodium-ammonia clusters, formation of the solvated electron was found to coincide with an ammonia molecule entering the second salvation shell, whereas for lithium-methylamine, electron salvation was not observed for the largest cluster studied, Li(NHCH3)4.
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O'Shaughnessy, Paul. "Alkali metal complexes of phosphorus donor ligands." Thesis, University of Newcastle Upon Tyne, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.323668.
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Skipper, N. "The alkali metal ions in aqueous solutions." Thesis, University of Bristol, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.379533.
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Nogueira, F. B. "Electrochemical testing of alkali metal-oxygen batteries." Thesis, University of Liverpool, 2018. http://livrepository.liverpool.ac.uk/3019388/.
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Ramsay, Donna Louise. "Alkali-metal-mediated cleave and capture chemistry." Thesis, University of Strathclyde, 2015. http://oleg.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=25765.
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Whilst metallation, a fundamental reaction in synthetic chemistry, is well established with mono-metallic organolithium reagents, recently a second generation of bimetallic reagents has been gathering momentum, evading some of the limitations associated with organolithium reagents. This study extends the current research in this area of synergic bimetallic chemistry and reports the synthesis and characterisation of new compounds from reactions of bases with different substrates, as well as detailed studies of the starting reagents. A new method for synthesising the utility organoamidolithium reagent LiTMP by way of a transmetallation reaction between tBuLi and Zn(TMP)₂ is described. This realised a new crystalline polymorph of LiTMP in the cyclotrimer (LiTMP)₃ 2.1. Remarkably an interrogation of the two most popular aluminating reagents “LiTMP·Al(iBu)₃” 3.1 and “LiTMP·Al(TMP)(iBu)₂” 3.2 established that 3.1 is not a single species as previously reported but in fact a complex mixture of five distinct species all in equilibria with each other. Additionally it was discovered that the modus operandi of both reagents is a two-step lithiation - trans-metaltrapping protocol, and not by direct alumination. The pharmacologically relevant amine DMPEA was studied with a range of bimetallic base mixtures. Post metallation and subsequent β-elimination the NMe₂ fragment was captured in three different crystalline compounds: [TMEDA·Na(TMP)(NMe₂)Zn(tBu)] 4.2, [PMDETA·Li(NMe₂)Zn(tBu)₂] 4.3 and [THF·Li(TMP)(NMe₂)Al(iBu)₂] 4.4. The first crystal structure where DMPEA is bonded to a metal has also been revealed in [DMPEA·Li(TMP)Zn(Me)₂] 4.5. Probing ferrocene with bimetallic mixtures afforded a range of mono- and dideprotonated products depending on the stoichiometry used. Both zincations in TMEDA·Na(μ-TMP)[μ-(C₅H₄)Fe(C₅H₅)]Zn(tBu) 5.1 and [TMEDA·Na(μ-TMP)Zn(tBu)]₂(C₅H₄)₂Fe 5.2 and aluminations in THF·Li(μ-TMP)[μ- (C5H4)Fe(C5H5)]Al(iBu)2 5.4, [THF·Li(μ-TMP)Al(iBu)2]2(C5H4)2Fe 5.5, [TMP(H)·Li(μ-TMP)Al(iBu)2]2(C5H4)2Fe 5.6 and TMP(H)·Li(TMP)[(C5H4)Fe(C5H5)]Al(iBu)2 5.7 were possible. The zinc system also provided the novel ferrocenophane type structure [{Fe(C₅H₄)₂}₂{Na₂Zn₂(tBu)₂·(THF)₆}] 5.8, as well as hints of a possible polymetallated product.
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Scott, David M. "Low-energy collisions of alkali-metal anions." W&M ScholarWorks, 1986. https://scholarworks.wm.edu/etd/1539623761.
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Measurements of the total cross section for electron detachment, (sigma)(,e)(E), are presented for low-energy (E(,1ab) < 300 eV) collisions of Na('-), K('-), and Cs('-) with atomic and molecular targets. For many of the atomic (rare-gas) targets, the energy dependence of (sigma)(,e)(E) is striking: virtually no detachment is observed until relatively high collision energies (50 eV in the center-of-mass frame) are reached, in contradistinction to what has been observed for similar collisions involving H('-). The thresholds for alkali anion detachment are approximately equal to the thresholds for excitation observed in collisions of neutral alkali atoms with these same targets. The similarity between the dynamics of the neutral system and that of the negative ion system, together with the observation (at greater energies) of detachment accompanied by excitation of the alkali parent, suggests that electron detachment may be mediated by a two-electron process in some cases. A simple curve-crossing mechanism adequately reproduces the observed (sigma)(,e)(E) for several of these rare-gas targets.;Measurements of both (sigma)(,e)(E) and the cross section for charge transfer (sigma)(,i)(E) have also been completed for H(,2), D(,2), N(,2), O(,2), CO, CO(,2), SO(,2), N(,2)O, CH(,4), and SF(,6) targets. Electron detachment is the dominant process for all of these targets except O(,2), SO(,2), and SF(,6), with thresholds on the order of a few eV. Structure in (sigma)(,e)(E) for the CO(,2) target has been attributed to charge transfer to a metastable state of CO(,2)('-)(('2)A(,1)). Similarly, in the case of N(,2)O, both (sigma)(,e)(E) and (sigma)(,i)(E) exhibit behavior which suggests that a temporary negative ion state is formed during the collision. In the case of the O(,2), SO(,2), and SF(,6) targets, charge transfer is observed to have particularly large cross sections (>100 (ANGSTROM)('2)) at low collision energies.
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Hopman, Martyn. "Organometallic compounds with bulky, phenyl-substituted, or derived donor-substituted ligands." Thesis, University of Sussex, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.285105.
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Boesveld, Willem Marco. "Reactions of 1,3,5-triazine with alkali metal amides and alkyls, and related chemistry." Thesis, University of Sussex, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.298104.
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Davidson, Matthew Gwilym. "Alkali and alkaline earth metal complexes of multifunctional amines : syntheses, structures and uses." Thesis, University of Cambridge, 1994. https://www.repository.cam.ac.uk/handle/1810/272659.
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Cao, Yu. "Mass spectrometric study of alkali metal containing ions." Diss., Georgia Institute of Technology, 1993. http://hdl.handle.net/1853/27890.
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Reinhold, Catherine Janey. "Reduced species in alkali metal loaded framework materials." Thesis, University of Birmingham, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.289728.
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Gregory, David. "Charge transfer studies of alkali-metal/semiconductor interfaces." Thesis, University of Liverpool, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.240051.
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Reichmuth, Andreas. "Alkali metal adsorption and ultra-thin film growth." Thesis, University of Cambridge, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.338308.
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Hogg, Lorna. "Alkali-metal-mediated metallations with emphasis on zincations." Thesis, University of Strathclyde, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.501820.
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Anderson, Paul Alexander. "Electron traps and delocalization in alkali metal zeolites." Thesis, University of Cambridge, 1991. https://www.repository.cam.ac.uk/handle/1810/270396.
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Tojo, Satoshi. "Attenuated total reflection spectroscopy on alkali-metal atoms." 京都大学 (Kyoto University), 2003. http://hdl.handle.net/2433/148543.
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Roy, Stephen Campbell. "Alkali metal beams from solid state electrochemical sources." Thesis, University of St Andrews, 1995. http://hdl.handle.net/10023/15526.
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All solid state electrochemical cells capable of producing beams of lithium, sodium and potassium in ultrahigh vacuum have been developed and investigated. The evolution of alkali metal vapour has been demonstrated by deposition of the metal on a substrate during polarisation of the cell followed by ex-situ analysis of the metal using laser ionisation mass analysis (LIMA). The electrochemistry of alkali metal evolution from these unusual solid state cells has been investigated using cyclic voltammetry, chronoamperometry and AC impedance measurements at pressures of 10−3 mbar and 10−8 mbar (UHV). It has been found for all three sources that the mechanism at relatively high pressure involves the nucleation and growth of liquid alkali metals or compounds containing alkali metals on the working electrode prior to their evaporation. In UHV the mechanism for potassium and sodium emission appears to involve the transfer of atoms directly into the gas phase whereas lithium exhibits nucleation and growth. In order to obtain a more complete characterization of the electrochemical mechanisms a spectro-electrochemical technique involving the simultaneous mass spectrometric analysis of the evolved vapour under UHV conditions along with cyclic voltammetry was developed. The formation of p-type ZnSe is essential to the fabrication of blue light emitting diodes and semiconductor lasers but has long represented a major problem in optoelectronics. This work shows that the potassium source can be used to p-dope ZnSe during growth of the material by molecular beam epitaxy (MBE). Efforts directed to the preparation of n-type diamond using a lithium source in microwave enhanced chemical vapour deposition (MWECVD) apparatus have demonstrated that the source can introduce lithium to diamond, although full semiconductor characterization of this material has yet to be made.
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Matranca, Guillermo. "New Jellium Model for Alkali Metals and its Future Applications to Metal Clusters." FIU Digital Commons, 2012. http://digitalcommons.fiu.edu/etd/657.
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This research develops a new method for understanding the properties of materials. The new method was applied to alkali metals to examine how well it can predict the Wigner-Seitz radius, rs. Pseudo-potentials for the individual atoms were generated and utilized to obtain the interaction energy within these metals.
The system involves 4 coulombic charges; two of them are the result of the neutral atom (one valence electron and one positive core charge for alkali atoms) and the other two are background charges of equal and opposite amount. This coulombic interaction will behave differently depending on the element that composes the system. There are four groups of energy for this system. One of them has the appearance of the Jellium model, which is solved with Density Functional Theory. From the other three groups, one of them will alter the minimum of the Jellium model for different elements in the system. This group is partially calculated with the help of Ewald summation. This calculation exemplifies that bcc is favored since it is lower in energy than fcc, which is in agreement with experiments for alkali metals. The correction to this energy will be due to the core electrons' interaction with a uniform negative charge background. This new method will also be beneficial to calculate the ground state energy of clusters by introducing surface boundaries in the system.
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Norris, Andrew George. "Alkali metal and simple gas atom adsorption and coadsorption on transition metal surfaces." Thesis, University of Liverpool, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.366717.
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Gareh, James Edward. "Preparations and properties of the alkali metal niobium disulphides." Thesis, University of Nottingham, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.240256.
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Illingworth, James M. "Chemical activation of biomass fibre with alkali metal salts." Thesis, University of Leeds, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.417756.
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Thompson, Helen. "The structure and dynamics of alkali metal-amine solutions." Thesis, University College London (University of London), 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.405891.
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Forbes, Glenn Chalmers. "The synergy of mixed alkali metal-zinc amine systems." Thesis, University of Strathclyde, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.401322.
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Orr, Samantha Alana. "Advancing alkali metal dihydropyridine chemistry : syntheses, structures and applications." Thesis, University of Strathclyde, 2017. http://digitool.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=28746.
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This project develops the chemistry of Group 1 dihydropyridines, a class of compound previously largely confined to lithium. A synthetic approach to sodium and potassium derivatives has been optimised via metathesis, the new compounds have been thoroughly characterised and the catalytic ability of the family has been assessed. Firstly, the previously reported lithium dihydropyridine (LiDHP) proved a valuable precursor to access five new s-block dihydropyridines that have been isolated and characterised by X-ray crystallography and NMR spectroscopy. The isomerisations of the 1,2- to the 1,4- isomeric forms have been monitored by NMR spectroscopy. Thermal studies on the non-solvated derivatives were performed and related to their ability to release metal hydride. Their proficiency to act as metal hydride surrogates was confirmed in reactions reducing benzophenone. Secondly, the first catalytic role of LiDHPs was established in the successful catalysed dehydrogenative cyclisation of diamine boranes. It was found that the LiDHP catalyst could compete with a ruthenium catalyst to prepare desired 1,3,2-borolidines. A three-step mechanism has been suggested, (deprotonation, β-hydride elimination and intramolecular hydrogen loss) supported by crystallographically characterised intermediates and extensive NMR studies. Formed in situ, the borolidines were further functionalised to more synthetically useful phenylborane derivatives. The LiDHP was next subjected to a further catalytic screening for hydroboration of carbonyls. This also proved successful for preparing boronate esters, from a range of aldehydes and ketones with pinacolborane. The reaction was thought to proceed akin to that reported in the literature, namely a hydrometallation followed by a metathesis step. However, an acceptor-donor adduct of pyridine and pinacolborane, characterised by X-ray crystallography, provided insight to a potential alternative pathway in the catalytic cycle. Finally, expanding on the monometallic dihydropyridines, six new heterobimetallic dihydropyridine complexes, Li/Al, K/Al and K/Zn, have been synthesised andcrystallographically characterised. Their structural assembly is contrasted with similar literature complexes.
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Blackley, Caroline Laura-Anne. "Ultracold scattering of alkali-metal atoms in magnetic fields." Thesis, Durham University, 2015. http://etheses.dur.ac.uk/11202/.
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This thesis reports on calculations of the scattering properties of a variety of ultracold alkali-metal mixtures. In particular, we have calculated the scattering properties of homonuclear mixtures of 85Rb, in a variety of incoming channels, and we have calculated the properties of heteronuclear mixtures of the isotopologues of Rb and Cs, and K and Cs. In general, we are interested in the location and character of Feshbach resonances in these mixtures with a view towards ultracold molecule formation. In 85Rb there is a rich Feshbach structure and potential uses for the resonances that we find, in the scattering lengths of the various incoming channels, are discussed. In 85RbCs there is a rich Feshbach structure and the prospects for ultracold molecule formation using this system are detailed. Similarly, we detail the Feshbach resonances of 87RbCs and discuss our results in the context of the successful formation of ultracold ground-state molecules. In the isotopologues of KCs each system has a rich Feshbach structure and we detail the location and width of the resonances, as well as the potential for ultracold molecule formation using each of the isotopes of potassium. In addition to scattering calculations, we have also calculated the location and character of the highest-lying bound states of each system. We have investigated the energy dependence of the scattering length using accurate coupled-channel calculations on 6Li, 39K and 133Cs to explore the behaviour of the effective range in the vicinity of both broad and narrow Feshbach resonances. We present an alternative parametrization of the effective range and further demonstrate that an analytical form of an energy and magnetic field-dependent phase shift, based on multichannel quantum defect theory, gives accurate results for the energy-dependent scattering length. Lastly, we examine the effect of additional external fields on alkali-metal collisions and discuss how external fields can be used to manipulate the interaction properties of a system.
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Gallagher, Neal Benjamin. "Alkali metal partitioning in a pulverized coal combustion environment." Diss., The University of Arizona, 1992. http://hdl.handle.net/10150/185896.
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Fouling, slagging, corrosion, and emission of submicron particulate from pulverized coal combustors have been linked to vapor alkali. Size segregated fly ash samples extracted from a 17 kW down-fired pulverized coal combustor showed strong evidence of alkali vaporization. The fraction of sodium in sizes smaller than 0.65 μm (f(8A)) showed a correlation with acid soluble sodium divided by total silicates in the parent coal. Addition of silicates to coal reduced f(8A) for sodium. Potassium existing primarily in the mineral matter, did not show a similar correlation, but f(8A) for potassium did correlate with f(8A) for sodium. Bench scale experiments indicated potassium does not vaporize in the presence of Na or Cl alone, but requires both, and was only released when sodium was captured. Additional of sodium acetate to coal increased f(8A) for potassium. Equilibrium calculations, experiment, and modelling of sodium capture by silicates during pulverized coal combustion identified several important mechanisms governing alkali behavior. The mode of occurrence of alkali in the parent coal dictates its ability to vaporize, its release kinetics, and its sate as it diffuses to the char surface. Other species such as chlorine, sulfur, moisture, and other metals influence alkali stability in the vapor, its reactivity, and its condensation characteristics. Char oxidation can influence alkali vaporization, and capture by affecting included silicate surface area. Sodium reaction with silicates captures from 70 to over 95% of total sodium for typical coals. Silicate additive appears to be a viable technique for reducing the fraction of alkali in the vapor during combustion.
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Bao, Wei. "Exploration of the catalytic use of alkali metal bases." Thesis, University of Edinburgh, 2017. http://hdl.handle.net/1842/28799.
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This PhD thesis project was concerned with the use of alkali metal amide Brønsted bases and alkali metal alkoxide Lewis bases in (asymmetric) catalysis. The first chapter deals with formal allylic C(sp3)–H bond activation of aromatic and functionalized alkenes for subsequent C–C and C–H bond formations. The second chapter is focused on C(sp3)–Si bond activation of fluorinated pro-nucleophiles in view of C–C bond formations. In the first chapter, a screening of various metal amides, hydrides, and alkyl reagents resulted in the observation that alkali metal amides were effective Brønsted bases to trigger allylic C(sp3)–H bond activation of aromatic alkenes at room temperature. Sodium hexamethyldisilazide was found to be most efficient compared with other s-, p-, d-, and fblock metal amides. This unique transition metal-free methodology was exploited to activate a variety of alkene pro-nucleophiles, which were shown to undergo γ-selective C–C bond formation with various aromatic aldimines as well as one aliphatic substrate. The corresponding homoallylic amine derivatives were obtained in high yields with excellent E:Z ratios. The reaction mechanism was investigated and attempts to detect and/or isolate key intermediates were undertaken. Importantly, it was shown that metal-free superbases of the Schwesinger or Verkade type were not apt to catalyse this challenging C–C bond formation. The asymmetric version of this rare sodium amide catalysis has been achieved by using a commercially available enantiopure bisoxazoline ligand (46% ee). Subsequently, the catalytic use of sodium and potassium amides was applied to the isomerization of terminal aromatic alkenes to generate the thermodynamically more stable internal olefins in excellent yields with high E:Z ratios. Furthermore, functionalized metalloid (B, Si) and metal-free alkenes were found to undergo alkali metal amide-triggered (chemoselective) allylic C(sp3)–H bond activation in view of isomerization and/or C–C bond formation with aldimines. In the second chapter, the catalytic C–Si bond activation of an important difluoromethylation reagent, HCF2SiMe3, was investigated. Here, alkali metal alkoxides were shown to be more effective Lewis base triggers than other metal alkoxides or metal-free superbases. This novel method was successfully used to transfer the nucleophilic difluoromethyl fragment to electrophiles such as a variety of amides and lactams, whereas unsaturated amides failed to undergo the intended conjugate C–C bond formation. In this context, it is noted that the α-hydrogen of certain amides was tolerated. This unprecedented catalytic difluoromethylation of unactivated carbonyl electrophiles was achieved using potassium tert-butoxide at room temperature, and the corresponding fluorinated ‘hemiaminal’ products were obtained in high yields.
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Chen, Chun-che. "Correlation between electrical and magnetic properties in alkali and alkaline earth metal doped lanthanum manganites /." Digital version accessible at:, 1999. http://wwwlib.umi.com/cr/utexas/main.
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Nandi, Debasis. "Physico - chemical investigations on the ion-solvent interactions of Tetraalkylammonium and alkali metal halides in non-aqueous solvents and their aqueous binary mixtures." Thesis, University of North Bengal, 1989. http://hdl.handle.net/123456789/718.
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Tonti, Dino. "Photoelectron spectroscopy Study of the intercalation reaction of alkali metals in transition metal dichalcogenides." [S.l. : s.n.], 2000. http://www.diss.fu-berlin.de/2000/145/index.html.
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Hörnis, Helmut Georg. "Equilibrium structures of clean and alkali covered metal (110) surfaces." Diss., Georgia Institute of Technology, 1994. http://hdl.handle.net/1853/30284.
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Chapman, Richard G. "Structure and electronic properties of expanded alkali fluids." Thesis, University of Oxford, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.329925.
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Lowton, Rebecca L. "Structural and thermogravimetric studies of alkali metal amides and imides." Thesis, University of Oxford, 1999. http://ora.ox.ac.uk/objects/uuid:df7b324d-c33d-4265-91cb-0555c3a10bec.
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This work presents an in-depth study of the crystal structures and hydrogen sorption potential of the Li - N - H and Li - Na - N - H systems. The structures of the materials have been studied using X-ray and neutron diffraction, Raman spectroscopy and inelastic neutron scattering. The behavior of the materials during heating was studied using variable temperature X-ray diffraction, intelligent gravimetric analysis in conjunction with neutron diffraction, intelligent gravimetric analysis combined with mass spectrometry and differential scanning calorimetry. The role of cation disorder in the Li - N - H (D) system has been explored, indicating that crystallographic ordering of the Li+ ions within lithium amide and lithium imide significantly affects the hydrogen sorption properties of the materials. Order-disorder transitions were observed both during hydrogen desorption from ordered LiNH2 and during deuterium adsorption on ordered Li2ND. Such transitions were not observed in disordered samples of the materials. The intrinsic disorder and the stoichiometry of Li - N - H(D) materials was shown to depend strongly on the techniques used during their synthesis. Studies regarding the synthesis, crystal chemistry and decomposition properties of the mixed Li / Na amides are presented. Two distinct mixed Li / Na amides of formulae Li3Na(NH2)4 and LiNa2(NH2)3 were observed in the LiNH2 / NaNH2 phase space. Na was also seen to be soluble in LiNH2, forming sodium-doped LiNH2 . Li3Na(NH2)4 and Na-doped LiNH2 were found to exhibit significant cation non-stoichiometry, whereas LiNa2(NH2)4 was shown to exist as a line phase material. Thermogravimetric and calorimetric studies of the mixed Li / Na amides suggested that these materials decompose primarily with loss of H2.
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Hopkins, A. D. "Group 15/alkali metal complexes and applications to photoemissive materials." Thesis, University of Cambridge, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.604223.
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The research presented in this thesis falls into four related areas. The synthetic approach used in all studies was the stepwise deprotonation of primary amines and phosphines with Group 15 dimethylamido reagents to produce heterobimetallic Group 15/alkali metal complexes. The principal aim was to examine the decomposition of these species, potentially into photoemission alkali metal antimonate layers. After an initial introduction (Chapter 1) detailing previous methods of synthesis of imido heterobimetallic complexes and photodiode materials, there follows an experimental section (Chapter 2) in which all the experimental details of the various synthetic studies are collected. Chapter 3 deals with the synthesis and characterisation of a range of heterobimetallic complexes of antimony and heavy alkali metals using the stepwise deprotonation of primary amines. Then presented is the first application of the stepwise deprotonation technique to primary phosphines (Chapter 4), demonstrating a direct comparison with heterometallic imido cages. Also presented is the decomposition of the new phosphinidene complex produced into Zintl compounds, providing a low-temperature route to these species. The applications of a heterometallic Sb/Li phopshinidene complex and an Sb/Li Zintl compound to the formation of photosensitive alloys is investigated and measurements show that photoactive materials are accessible via this route. In Chapter 5 the decomposition of phosphinidene complexes into Zintl compounds is probed. The formation of heterocyclic anions of the type [(RP)nE]- (E=Sb, As) in various reactions of [E(NMe2)3] with [RP(H)Li]n and [RPH2] (R=cyclohexyl, tertiary butyl) suggests that Zintl compounds are generated via these species. In Chapter 6 the study shifts its focus to the synthesis of heterometallic As/alkali metal complexes containing [As2(NCy)4]2- anions (Cy=cyclohexyl) and the investigation of the co-ordination chemistry of this species. The theme of ligand synthesis is continued in Chapter 7, where anionic species containing P-P and P-As frameworks are developed.
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Aldous, I. M. "Non-aqueous spectroelectrochemistry of dioxygen for alkali metal-oxygen batteries." Thesis, University of Liverpool, 2016. http://livrepository.liverpool.ac.uk/3004124/.
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The rechargeable non-aqueous alkali metal-oxygen batteries (also referred to as ‘metal-air’ batteries), such as lithium and sodium-air, offer improved energy storage opportunities over other existing battery systems. Some severe technological problems need to be addressed for the successful development of this system into a commercially viable device. The development of efficient cathode materials and stable electrolytes that allow the reversible electrochemical reduction of oxygen is an area where significant research is necessary. For example, lithium oxygen (Li-O2) cells generate electrical current when lithium ions react with reduced oxygen at the negatively polarised electrode during discharge, the as formed LixO2 reaction products can be reversed during the charging cycle. The problem is that the discharge products (superoxides and peroxides of lithium and sodium) and the metastable intermediates formed are highly reactive, and conventional battery electrolytes easily degrade in their presence. For a greater understanding of the oxygen reduction mechanism and for the direct detection of the intermediates and reaction products formed during the oxygen reduction process, surface sensitive spectroscopy techniques can be utilised. The development of in situ spectroelectrochemical environments for such a purpose is a technical challenge that is unique to each spectroscopy. The information herein has been obtained through in situ surface enhanced Raman spectroscopy (SERS) and UV/Vis spectroscopy in conjunction with common electrochemical techniques. The Raman effect is weak and careful preparation of the surface is necessary to provide enhancement of Raman signals from surface present species during O2 reduction. UV/Vis provides different challenges in the preparation of a sealed electrochemical environment, which the cell and working electrode are transparent to UV/Vis light. Chapter 4 describes the how the size of the supporting salt (tetra alkyl ammonium) cation influences both the electrokinetic and voltage hysteresis between oxygen reduction and evolution reactions (ORR and OER). This was found to be due from the rearrangement of the cation at the electrode interface, under potential control. The use of in situ SERS was used in Chapter 5 to study the effect of solvent on the ORR in the presence of Na+. The findings conclude a solvent dependent mechanism whereby highly solvating solvents like amides and sulfoxides detect only NaO2, and nitriles and glymes detect Na2O2 as respective discharge products. A comparative study of the effect of alkali metal cation size is discussed in Chapter 6 showing the changes in reversibility of O2 with cations of increased ionic radius. Larger cations, such as Na+, K+ and Cs+ display quasi-reversibility, as opposed to the irreversibility of Li+. Finally in Chapter 7 the detection and characterisation of the electronic state of oxygen released from electrooxidised Li2O2, NaO2 and KO2 was obtained through in situ UV/Vis spectroscopy. Li2O2 producing a higher percentage of reactive singlet oxygen per mass of oxidised discharge product compared with NaO2 and KO2. Within this chapter initial findings of a known singlet oxygen sink, 1,4-diazabicyclo[2.2.2]octane (DABCO), is discussed as a possible electrolyte additive.
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Liu, Yinzhe. "Low melting point alkali metal borohydride mixtures for hydrogen storage." Thesis, University of Birmingham, 2018. http://etheses.bham.ac.uk//id/eprint/8447/.
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With relatively high gravimetric and volumetric hydrogen capacities and low hydrogen operating pressures, borohydrides are being investigated for their potential use as solid-state hydrogen storage media. This work focuses on investigating the hydrogen sorption mechanisms for \(LiBH_4\)-based low-melting-point borohydride mixtures (e.g. \(0.62LiBH_4\)-\(0.38NaBH_4\), \(0.75LiBH_4\)-\(0.25KBH_4\)), and their destabilized systems using selected additives. Solid solutions and bimetallic borohydride are found in the as-prepared \(0.62LiBH_4\)-\(0.38NaBH_4\) and \(0.75LiBH_4\)-\(0.25KBH\) mixtures, respectively. Under Ar, the \(0.62LiBH_4\)-\(0.38NaBH_4\) mixture releases 10.8 wt.% of hydrogen at 650 °C; whilst the \(0.75LiBH_4\)-\(0.25KBH_4\) mixture releases 8.9 wt.% of hydrogen at 700 °C. Their dehydrogenation peak temperatures are strongly affected by Na+ or K+ and therefore higher than \(LiBH_4\). These mixtures have poor cycling stabilities. Additives, such as micron-sized \(SiO_2\) and nano-sized Ni, cannot affect their melting points; but they cause lower dehydrogenation temperatures, decrease the hydrogen evolution, and facilitate the formation of metal dodecaborates. Besides, the addition of nano-sized Ni cannot significantly improve the cycling stability; however, it leads to partial reversible \(LiBH_4\). Therefore, a further compositional optimization with respect to the rehydrogenation conditions, in parallel with the use of nano-confinement of the mixture via an infiltration approach, is needed before practical use of a low-melting-point alkali metal borohydride mixture.
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Kang, ShinYoung. "Ab initio prediction of thermodynamics in alkali metal-air batteries." Thesis, Massachusetts Institute of Technology, 2014. http://hdl.handle.net/1721.1/89952.
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Thesis: Ph. D., Massachusetts Institute of Technology, Department of Materials Science and Engineering, 2014.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 93-100).
Electric vehicles ("EVs") require high-energy-density batteries with reliable cyclability and rate capability. However, the current state-of-the-art Li-ion batteries only exhibit energy densities near ~150 Wh/kg, limiting the long-range driving of EVs with one charge and hindering their wide-scale commercial adoption.1-3 Recently, non-aqueous metal-O₂ batteries have drawn attention due to their high theoretical specific energy.2, 4-6 Specifically, the issues surrounding battery studies involve Li-O₂ and Na-O₂ batteries due to their high theoretical specific energies of 3.5 kWh/kg (assuming Li 20 2 as a discharge product in Li-O₂ batteries) and 1.6 and 1.1 kWh/kg (assuming Na₂O₂ and NaO₂ as discharge products, respectively, in Na-O₂ batteries). Since the potential of Li-O₂ batteries as an energy storage system was first proposed in 1996,1 various studies have criticized and verified their shortcomings, such as their low power density, poor cyclability, and poor rate capability. ₇, ₈ Substantial research attempts have been made to identify the cause of the high overpotentials and electrolyte decomposition and to search for better cathode/electrolyte/anode and/or catalyst material combinations. However, Li-O₂ battery technology remains in its infancy primarily due to the lack of understanding of the underlying mechanisms. Therefore, we investigate the charging mechanism, which contributes to the considerable energy loss using first-principles calculations and propose a new charging mechanism based on experimental observations and knowledge concerning Li-ion and Na-ion batteries. Most studies on metal-O₂ batteries have mainly focused on Li-O₂ batteries. However, recently, the promising performance of Na-O₂ systems has been reported.₉, ₁₀ Although Na-O₂ batteries exhibit slightly lower theoretical specific energies than those of the Li-O₂ batteries as specified above, the chemical difference between the two alkali metals substantially distinguishes the electrochemistry properties of Na-O₂ and Li-O₂. In the Na-O₂ system, both NaO₂ and Na₂O₂ are stable compounds, while in the Li-O system, LiO₂ is not a stable compound under standard state conditions (300 K and 1 atm).₁₁, ₁₂ Presumably, due to this chemical difference, the Na-O₂ system has exhibited a much smaller charging overpotential, as low as 0.2 V, when NaO₂ is formed as a discharge product, compared with that in Li-O₂ system, >1 V. Such a low charging overpotential in Na-O₂ batteries demonstrates their potential as a next generation electrochemical system for commercially viable EVs .₉,₁₀ In this thesis, we study the thermodynamic stability of Na-O compounds to identify the phase selection conditions that affect the performance of Na-O₂ batteries.
by ShinYoung Kang.
Ph. D.
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Blair, Victoria L. "Advances in alkali-metal-mediated manganation and comparisons with magnesiation." Thesis, University of Strathclyde, 2010. http://oleg.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=12391.
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Campbell, Ross. "Alkali metal mediated bimetallic main group and transition organometallic chemistry." Thesis, University of Strathclyde, 2012. http://oleg.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=16944.
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Robertson, Gemma Margaret. "New insights into homo- and heterometallic alkali metal amide chemistry." Thesis, University of Strathclyde, 2012. http://oleg.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=25788.
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Currently a hot topic in organometallic chemistry; bimetallic alkali metal magnesium (or zinc) reagents exhibit a unique ‘synergic’ chemistry which cannot be replicated by either monometallic component on its own. This research project focused on enhancing this chemistry by introducing chiral ligands into these bimetallic systems. The metallate chemistry of achiral cis-2,6-dimethylpiperidide (cis-DMP) is explored through the synthesis and characterisation of a series of bimetallic bases which contain this ligand. The bis(alkyl)amido lithium and sodium zincates [(TMEDA)·Li(μ-cis-DMP)Zn(tBu)2], 75 and [(TMEDA)·Na(μ-cis-DMP)(μ-tBu)Zn(tBu)], 76, were successfully prepared and characterised in both the solid- and solution-states, along with the bis(amido)alkyl sodium zincate [(TMEDA)·Na(μ-cis-DMP)2Zn(tBu)], 77, which was prepared from 76 via a ligand reorganisation process. In addition, the tris(amido) sodium magnesiates [(TMEDA)·Na(μ-cis-DMP)2Mg(cis-DMP)], 79 and [{cis-DMP(H)}·Na(μ-cis-DMP)2Mg(cis-DMP)], 80, are also presented. Surprisingly, little attention has been paid to cis-DMP despite its structural similarity to diisopropylamide (DA) and 2,2,6,6-tetramethylpiperidide (TMP). By comparison of the complexes produced herein with appropriate complexes from the literature, it has been possible to experimentally determine that the steric bulk of cis-DMP closely resembles that of DA but is considerably less bulky than TMP. Focusing on introducing the chiral diamines (−)-sparteine and N,N,Nʹ,Nʹ-(1R,2R)-tetramethylcyclohexane-1,2-diamine [(R,R)-TMCDA] into the molecular framework of bimetallic alkali metal zinc reagents, three bis(alkyl)amido sodium zincates were successfully prepared and characterised ‒ two of the form [{chiral diamine}·Na(μ-TMP)(μ-nBu)Zn(tBu)] [chiral diamine = (−)-sparteine for 96, (R,R)-TMCDA for 97], and the third [{(R,R)-TMCDA}·Na(μ-TMP)(μ-tBu)Zn(tBu)], 98. These complexes represent the first examples of (−)-sparteine or (R,R)-TMCDA being successfully incorporated within the molecular framework of an alkali metal/zinc synergic system [or indeed any alkali metal/divalent metal synergic system for (R,R)-TMCDA], and perhaps most significantly complex 98 is a chiral variant of a synthetically important utility ate base. Having investigated heterobimetallic systems containing chiral diamines, it was also deemed important to study the alkali metal building blocks, specifically chiral diamine adducts of the synthetically important lithium and sodium bis(trimethylsilyl)amides. ‘Conventional' (−)-sparteine adducts of lithium and sodium 1,1,1,3,3,3-hexamethyldisilazide (HMDS) were prepared and characterised, [MHMDS·(−)-sparteine] (M = Li for 106, Na for 107), along with an unexpected and ‘unconventional’ hydroxyl-incorporated solvent-separated hexanuclear sodium sodiate, [(−)-sparteine·Na(μ-HMDS)Na·(−)-sparteine]+[Na4(μ-HMDS)4(μ4-OH)]−, 108. Following this unusual result, a similar complex containing (R,R)-TMCDA was prepared and characterised, namely the hydroxyl-incorporated solvent-separated pentanuclear sodium sodiate [Na{(R,R)-TMCDA}2]+[Na4(μ-HMDS)4(μ4-OH)]−, 109. Given that both of these diamine-NaHMDS systems have formally captured monomeric NaOH, we envisaged that similar systems could encapture substoichiometric quantities of other salts, particularly the Lewis amphoteric metal halides, and in doing so, develop a new Group 1 macrocyclic/supramolecular family of complexes. Initially concentrating on LiHMDS systems and investigating several approaches in reaching this goal, we successfully isolated four solvent-separated ion pair complexes; two of the form [Li·{(R,R)-TMCDA}2]+[Li5(μ-HMDS)5(μ5-X)]− (where X = Cl for 115, Br for 116); and two of the form [Me6-TREN·Li(μ-X)Li·Me6-TREN]+[Li5(μ-HMDS)5(μ5-X)]− [where Me6-TREN = tris[2-(dimethylamino)ethyl]amine and X = Cl for 117, Br for118]. The former two complexes have captured one LiX unit and the latter two complexes two LiX units (bearing parallels with 108 where an additional monomeric NaHMDS unit has been trapped). The anions of these complexes ‒ ten-membered (LiN)5 rings (which host halide guests) ‒ are unprecedented.
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Rodrigo, Udaya Indike. "ULTRAFAST PHOTOEXCITATION STUDIES OF CONCENTRATED SOLUTIONS OF ALKALI METAL HALIDES." Bowling Green State University / OhioLINK, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1154537086.
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Ye, Songtao. "Ion-Pair Behavior Between Polyoxometalates Anion and Alkali Metal Cation." University of Akron / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=akron1522253761785623.
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Chapman, James Oliver. "Alkali metal doped graphene : superconductivity, structural, magnetic and optical properties." Thesis, University of Manchester, 2015. https://www.research.manchester.ac.uk/portal/en/theses/alkali-metal-doped-graphene-superconductivity-structural-magnetic-and-optical-properties(0ae09e60-4104-465a-a5ad-9cd2d6816661).html.
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Intercalation of graphite with alkali metals has previously been shown to, in some cases, produce superconducting compounds from the two non-superconducting components. The use of graphene as a basis to continue this research offers new possibilities as confinement of intercalant species is reduced from bulk graphite. Papers comprised of exfoliated graphene flakes were doped with Li, Cs, K and Ca atoms via vapour transport methods in order to investigate superconducting properties. While Li, Cs and K-doping showed no signs of a superconducting transition as low as 1.8 K, observed through magnetic measurements, Ca-doped graphene became superconducting below 6.4 K – a lower transition temperature than Ca-doped graphite, TC = 11.5 K. The carrier concentration could also be changed using composite papers made from graphene and various proportions of insulating boron nitride flakes, allowing TC to be varied. Optical reflectivity spectra were used to determine the level of doping present in each compound, directly calculated from their estimated plasmon energy. Ca-doped graphene paper exhibited a 20% lower carrier concentration than Ca-intercalated graphite, offering an explanation for the lower value of TC. To allow insight into the partial doping of graphene papers, samples were exposed to air and monitored via dynamic x-ray diffraction techniques and optical analysis during degradation. With prolonged reaction in air, the carrier concentration was found to drop monotonically, while the interlayer separations contracted as intercalant species vacated the structure, leaving an arrangement of flakes similar to that of the initial, un-doped, graphene paper. The range of carrier concentrations observed suggests that doping of graphene flakes is non-discrete, thus implying tunable TC.
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Whittaker, Kate Avril. "Construction and characterisation of ultra-thin alkali-metal vapour cells." Thesis, Durham University, 2017. http://etheses.dur.ac.uk/12112/.
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This thesis presents the study of thermal alkali-metal vapours confined in a layer with a sub-micron thickness. This confinement enables the study of high density media without the loss of signal present in usually thermal vapours, but also has additional effects on spectra acquired from the system. Such effects include the suppression of the Doppler broadening and the interaction of the atoms with nearby surfaces. Herein, we present a study of this atom-surface interaction in both Rubidium and Caesium atoms, demonstrating that the interaction follows a power law of $1/r^\alpha$, where $\alpha = 3.02 \pm 0.06$. We also study Rabi oscillations at high densities, driving GHz Rabi oscillations in a Rb vapour at densities up to $10^17$~cm$^{-3}$. We find that the results do not have sufficient agreement with an optical Bloch simulation, but Maxwell Bloch simulations indicate the possible presence of simultons; simultaneously propagating solitons. Such phenomena have not yet been observed out of crystalline media. We also present a study of causality relations in atomic media. We first discuss the equivalency of the Hilbert transform to the Kramers-Kronig relations, well known in signal processing, but rarely applied in atomic physics. We then demonstrate that the Hilbert transform can be applied to atomic transmission spectra to quickly generate refractive index spectra. The final section of this thesis fully details the successful design and fabrication of vapour cells with a thickness of 500-1500~nm. The cells are assembled using a combination of traditional scientific glass blowing techniques and thermally annealed optically contacted plates. We fully outline the production process, and then present evidence of their successful functionality and longevity.
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Solomon, Sophia Astero. "Allyl and pentadienyl carbanion complexes of alkali metals : metal- and functionality-directed structure and bonding." Thesis, University of Manchester, 2011. https://www.research.manchester.ac.uk/portal/en/theses/allyl-and-pentadienyl-carbanion-complexes-of-alkali-metals-metal-and-functionalitydirected-structure-and-bonding(a88c30ae-8e8c-49e5-86d7-cc95569aab72).html.
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Five ansa-tris(allyl) complexes [(PhSi{C3H3(SiMe3)}3)(Li?tmeda)3] (2.1), [(MeSi{C3H3(SiMe3)}3)(Li?pmdeta)3] (2.2), [(MeSi{C3H3(SiMe3)}3)-(Na.tmeda)3] (2.3), [(PhSi{C3H3(SiMe3)}3)(Na?tmeda)2Na]2 [2.4]2 and [(MeSi-{C3H3(SiMe3)}3)(K?OEt2)2(KLi{OtBu})]2 [2.5]2 have been synthesised, and studied by X-ray crystallography and NMR spectroscopy. A collaboration was undertaken to study some of the complexes by DFT. Crystallographic studies have shown that the overall structure of the complex is dependent on a combination of several factors: the metal cation; the substituent on the central silicon atom for the ansa-tris(allyl) ligands; and the co-ligand, tmeda or pmdeta. (tmeda = N,N,N?,N?¬-tetramethylethylenediamine and pmdeta = N,N,N?,N?,N??-pentamethyldiethylene-triamine). Solution studies of the ansa-tris(allyl) complexes showed that the solid-state structures are maintained in solution. The first examples of donor-functionalised allyl pro-ligands have been synthesised and coordinated to a variety of s-block metals; [Li{(SiMe3)2C3H2(1-CH2C4H7O)}]2 [4.1]2, [Li{(SiMe3)2C3H2(1-CH2CH2OCH3)}]2 [4.2]2, [(thf)K{(SiMe3)2C3H2(1-CH2C4H7O)}]2 [4.5]? and [Mg{(SiMe3)2C3H2(1-CH2C4H7O)}2] (4.6). As with the ansa-tris(allyl) complexes, both X-ray crystallographic and NMR spectroscopy studies have been undertaken, and the structures of the donor-functionalised allyl complexes were found to be dependent on the metal cation, with each cation coordinated in a different manner by the allyl ligand. For the potassium allyl complex 4.5 there is complete delocalisation of the allyl negative charge, and it is ?3-coordinated in a polymeric structure. However for lithium complexes, [4.1]2 and [4.2]2, the donor-functionalised allyl ligand is ?2-coordinated, and the negative charge is only partially delocalised. The magnesium complex 4.6 has the allyl ligand coordinated via a ?-bond to the metal and the allyl has localised single and double bonds.Finally, the synthesis of the first two donor-functionalised pentadienyl ligands and their lithium complexes are reported. Complexes [(tmeda)Li{1,5-(SiMe3)2C5H4(CH2C4H7O)}] (6.1) and [(tmeda)Li{1,5-(SiMe3)2C5H4(CH2CH2OCH3)}] (6.2) are the first structurally characterised lithium pentadienyl complexes, and are the first donor-functionalised pentadienyl complex of any metal. As well as structural characterisation, complexes 6.1 and 6.2 have been investigated by NMR spectroscopy and collaborative DFT studies. X-ray crystallography revealed that both complexes have the W-conformation of the pentadienyl ligand ?2-coordinated to the lithium cation, as well as the ether oxygen atom and the tmeda nitrogen atoms. DFT studies showed that the most stable gas-phase structure of the 1,5-bis(trimethylsilyl)-pentadienyl anion is the W-conformation, but its lithium complex is most stable in the U-conformation. The [Li{1,5-(SiMe3)2C5H4(CH2CH2OCH3)}]? anion has the W-conformation and the U-conformation is isoenergetic, but the addition of tmeda gives the W-conformation as the most stable in both the gas-phase and in toluene. Finally NMR spectroscopy studies showed that in solution complexes 6.1 and 6.2 are either in the symmetrical U-conformation or in fluxional process with a very low activation energy.