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Synchrotron radiation studies of gas phase molecules : from hydrogen to DNA sugarsVall-llosera, Gemma January 2008 (has links)
This thesis summarises experimental results on the molecular spectroscopy of gas phase molecules excited by synchrotron radiation in the VUV and soft X-ray regions. We have used three different detection techniques, photon induced fluorescence spectroscopy, photoionisation mass spectroscopy and near edge X-ray absorption fine structure spectroscopy to study molecular deuterium, hydrogen sulphide, ammonia, methanol, pyridine, pyridazine, pyrimidine, pyrazine, s-triazine, and 2-deoxy-D-ribose, the last one also known as the DNA sugar. Out of this variety of techniques and molecules we have shown that: (1) high resolution dispersed fluorescence allows us to identify vibrational and rotational bands in molecular deuterium, as well as to estimate the predissociation probability of the same molecule [paper I]; (2) the main species fluorescing after core excitation of methane, ammonia [paper III], hydrogen sulphide [paper II], pyridine, pyrimidine and s-triazine is H Balmer α, followed by fluorescence from ionised species, molecular bands and Balmer β, γ , δ; (3) the Rydberg enhancement seen in fluorescence measurements of water [Melero et al. PRL 96 (2006) 063003], corroborated later in H2S [paper II], NH3 [paper III] and CH4 [paper III] and postulated as general behaviour for molecules formed by low-Z atoms, is also seen in larger organic cyclic molecules, e.g. azabenzenes; (4) when dissociative ionisation of pyridine, pyridazine, pyrimidine, pyrazine, s-triazine and 2-deoxy-D-ribose occurs, concerted bond rearrangement and nuclear motion takes place as opposed to stepwise dissociation [papers V and VI]. / QC 20100916
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Solving the quantum scattering problem for systems of two and three charged particlesVolkov, Mikhail January 2011 (has links)
A rigorous formalism for solving the Coulomb scattering problem is presented in this thesis. The approach is based on splitting the interaction potential into a finite-range part and a long-range tail part. In this representation the scattering problem can be reformulated to one which is suitable for applying exterior complex scaling. The scaled problem has zero boundary conditions at infinity and can be implemented numerically for finding scattering amplitudes. The systems under consideration may consist of two or three charged particles. The technique presented in this thesis is first developed for the case of a two body single channel Coulomb scattering problem. The method is mathematically validated for the partial wave formulation of the scattering problem. Integral and local representations for the partial wave scattering amplitudes have been derived. The partial wave results are summed up to obtain the scattering amplitude for the three dimensional scattering problem. The approach is generalized to allow the two body multichannel scattering problem to be solved. The theoretical results are illustrated with numerical calculations for a number of models. Finally, the potential splitting technique is further developed and validated for the three body Coulomb scattering problem. It is shown that only a part of the total interaction potential should be split to obtain the inhomogeneous equation required such that the method of exterior complex scaling can be applied. The final six-dimensional equation is reduced to a system of three dimensional equations using the full angular momentum representation. Such a system can be numerically implemented using the existing full angular momentum complex exterior scaling code (FAMCES). The code has been updated to solve the three body scattering problem. / At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 4: Submitted. Paper 5: Manuscript.
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Characterizing single atom dipole traps for quantum information applicationsShih, Chung-Yu 27 March 2013 (has links)
Ultracold neutral atoms confined in optical dipole traps have important applications in quantum computation and information processing, quantum simulators of interacting-many-body systems and atomic frequency metrology. While optical dipole traps are powerful tools for cold atom experiments, the energy level structures of the trapped atoms are shifted by the trapping field, and it is important to characterize these shifts in order to accurately manipulate and control the quantum state of the system.
In order to measure the light shifts, we have designed a system that allows us to reliably trap individual 87Rb atoms. A non-destructive detection technique is employed so that the trapped atoms can be continuously observed for over 100 seconds. Single atom spectroscopy, trap frequency measurements, and temperature measurements are performed on single atoms in a single focus trap and small number of atoms in a 1D optical lattice in order to characterize the trapping environment, the perturbed energy level structures, and the probe-induced heating.
In the second part of the thesis, we demonstrate deterministic delivery of an array of individual atoms to an optical cavity and selective addressability of individual atoms in a 1D optical conveyor, which serves as a potential candidate for scalable quantum information processing. The experiment is extended to a dual lattice system coupled to a single cavity with the capability of independent lattice control and addressability. The mutual interactions of atoms in different lattices mediated by a common cavity field are demonstrated. A semi-classical model in the many-atom regime based on the Jaynes-Cummings model is developed to describe the system that is in good qualitative agreement with the data. This work provides a foundation for developing multi-qubit quantum information experiments with a dual lattice cavity system.
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An apparatus for studying interactions between Rydberg atoms and metal surfacesCarter, Jeffrey David January 2007 (has links)
A system suitable for studying interactions between ⁸⁷Rb Rydberg atoms and metal surfaces has been constructed. This thesis describes the design and construction of the apparatus, and some test results. Atoms in a vapor cell magneto-optical trap are transferred to a macroscopic Ioffe-Pritchard trap, where they will be RF evaporatively cooled and loaded into a magnetic microtrap (atom chip). Confinement of cold clouds at controllable distances (5–200 μm)} from a metal surface is possible. The effects of atom-surface interactions can be studied with Rydberg atom spectroscopy.
Some functionality of the apparatus has been demonstrated. Approximately 1.5×10⁷ atoms were loaded into a mirror MOT, and about 6×10⁶ atoms were optically pumped to the |F=2, m_F=2> hyperfine ground state and confined in a macroscopic Ioffe-Pritchard trap. The temperature of the cloud in the trap was 42 ± 5 μK, and the 1/e lifetime is 1–1.5 s. Forced RF evaporation has been used to measure the magnetic field at the trap minimum, but RF evaporative cooling has not yet been demonstrated.
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An apparatus for studying interactions between Rydberg atoms and metal surfacesCarter, Jeffrey David January 2007 (has links)
A system suitable for studying interactions between ⁸⁷Rb Rydberg atoms and metal surfaces has been constructed. This thesis describes the design and construction of the apparatus, and some test results. Atoms in a vapor cell magneto-optical trap are transferred to a macroscopic Ioffe-Pritchard trap, where they will be RF evaporatively cooled and loaded into a magnetic microtrap (atom chip). Confinement of cold clouds at controllable distances (5–200 μm)} from a metal surface is possible. The effects of atom-surface interactions can be studied with Rydberg atom spectroscopy.
Some functionality of the apparatus has been demonstrated. Approximately 1.5×10⁷ atoms were loaded into a mirror MOT, and about 6×10⁶ atoms were optically pumped to the |F=2, m_F=2> hyperfine ground state and confined in a macroscopic Ioffe-Pritchard trap. The temperature of the cloud in the trap was 42 ± 5 μK, and the 1/e lifetime is 1–1.5 s. Forced RF evaporation has been used to measure the magnetic field at the trap minimum, but RF evaporative cooling has not yet been demonstrated.
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Jakten på ett roligare läromedel : - ett utvecklingsarbete om undervisning om atomenNarvesjö, Johanna January 2011 (has links)
Syftet med utvecklingsarbetet var att skapa ett genusneutralt läromedeli ämnet kemi om atomen för årskurserna 4-6. Nuvarande läromedelupplevs som för svåra och irrelevanta för eleverna som i stor gradtappar intresset i elvaårsåldern. Framför allt flickor upplever att ämnetinte är riktat till dem. Därför skapade jag ett material utan traditionelltmanliga inslag, för att inkludera alla elever. Fakta förenklades ochkonkretiserades så att den blev relevant och begriplig för eleverna.Produkten syftade till att vara åldersanpassad och kreativtstimulerande, då barns kunskaper gynnas av lekfullt lärande. Materialetbestod av texter och övningar med tillhörande praktiskt material.Produkten testades av åtta flickor och sju pojkar i årskurs fem. Åsikteroch synpunkter om produkten samlades in via en enkät. Enligtenkäterna skapade mitt material nyfikenhet för ämnet, både blandflickor och pojkar. De upplevde att de tittade och läste i boken för att detvar underhållande, inte för att de skulle lära sig något som står ikursplanen. Metoden att skapa ett annorlunda läromedel är ett enkeltknep för att tillvarata det naturliga intresset eleverna har.
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Synthesis and electrochemical studies of nitroxide radical polymer brushes via surface-initiated atom transfer radical polymerizationWang, Yu-Hsuan 27 July 2010 (has links)
A non-crosslinking approach that covalently bonds nitroxide polymer brushes onto the ITO substrates via surface-initiated atom transfer radical polymerization (ATRP) was develpoed. Since the indium tin oxide (ITO)-silane covalent bonding providesvery strong chemical bonds to adsorb the nitroxide polymer brushes on ITO, it prevents polymers from dissolving into electrolyte solvent and thus improves its electrochemical properties.
Moreover, micro-contact printing technology was used to pattern nitroxide polymer brushes on an ITO surface for the potential application in microbatteries. The morphology of electrodes was observed by atomic force microscopy.The electrochemical properties of the cathode were also studies.
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Nitroxide Polymer Brushes Grafted onto Silica Nanoparticles as Cathodes for Organic Radical BatteriesLin, Hsiao-chien 13 October 2011 (has links)
Nitroxide polymer brushes grafted on silica nanoparticles as binder-free cathode for organic radical battery have been investigated. Scanning electron microscopy, transmission electron microscopy, infrared spectroscopy and electron spin resonance confirm that the nitroxide polymer brushes are successfully grafted onto silica nanoparticles via surface-initiated atom transfer radical polymerization. The thermogravimetric analysis results indicate that the onset decomposition temperature of these nitroxide polymer brushes is found to be ca. 201 ◦C. The grafting density of the nitroxide polymer brushes grafted on silica nanoparticles is 0.74¡V1.01 chains nm−2.
The results of the electrochemical quartz crystal microbalance indicate that the non-crosslinking nitroxide polymer brushes prevent the polymer from dissolving into organic electrolytes. Furthermore, the electrochemical results show that the discharge capacity of the polymer brushes is 84.9¡V111.1 mAh g−1 at 10 C and the cells with the nitroxide polymer brush electrodes have a very good cycle-life performance of 96.3% retention after 300 cycles.
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Structural Vibration Analysis Of Single Walled Carbon Nanotubes With Atom-vacanciesDogan, Ibrahim Onur 01 February 2010 (has links) (PDF)
Recent investigations in nanotechnology show that carbon nanotubes (CNT) have one of the most significant mechanical, electrical and optical properties. Interactions
between those areas like electrical, optical and mechanical properties are also very promising in both research and industrial fields. Those unique characteristics are
built by mainly the atomistic structure of the carbon nanotubes.
In this thesis, the effects of vacant atoms on single walled carbon nanotubes (SWCNT) are investigated using matrix stiffness method. In order to use this
technique a linkage between structural mechanics and molecular mechanics is established. A code has been developed to construct the SWCNT with the desired
chirality, extracting the vacant atoms with the corresponding atomic bonds between the neighbor nodes and calculating the effect of those vacancies on its vibrational
properties. A finite element software is also utilized for validation of the code and results.
In order to investigate the convergence of the effect of those vacant nodes a numerous number of analyses have been carried out with randomly positioned vacant
atoms. Also consecutive vacant nodes have been positioned in order to investigate the effect on the structural properties through the length of a CNT. In addition to those, as a case study, the reduction in Young' / s modulus property
because of the vacancies has also been investigated and the effects are tabulated in
the report.
It is concluded in this study that the any amount of vacant atoms have substantial effect on modal frequencies and Young' / s modulus. Chirality and the position of the
vacancies are the main parameters determining the structural properties of a CNT.
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Approach Of International Organizations In Relation To Education, Development And Empowerment: Catom As An ExampleGuven, Ozen 01 July 2010 (has links) (PDF)
This thesis is meant to describe and analyze approach of international organizations in relation to education, development and empowerment as well as their role at the intersection of these three concepts. In its attempt to understand the nature of international involvement in education with a development discourse and particularly to see the effects of this involvement on the target groups of the projects and programs, the thesis explores Multi-Purpose Community Centers (Ç / ATOMs) in Turkey&rsquo / s southeast. The thesis identifies, on the one hand, that the Ç / ATOM project supports the analyses in the literature regarding the role of international organizations in the institutionalization of the idea of &lsquo / education for development&rsquo / and in the standardization and dissemination of their own discourses about this idea. On the other hand, the current work proposes that Ç / ATOMs as a project supported by international organizations have produced rather limited but meaningful outcomes in terms of its economic effects on the participants / however, more importantly, it has also created qualitative changes on the daily life of the beneficiaries, which may contribute to social transformation of the region in the long term.
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