Dissertations / Theses on the topic 'Materials Spectra'
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1
Bowmar, Paul. "Optical spectroscopy of novel materials." Thesis, University of Oxford, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.259758.
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Arshad, Khubaib, and Muhammad Mujahid. "Biodegradation of Textile Materials." Thesis, Högskolan i Borås, Institutionen Textilhögskolan, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:hb:diva-20862.
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In this research work different textile materials were buried in soil and their biodegrading pattern will be studied after different specific period of times.Program: Master Programme in Textile Technology
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Whittam, Anne J. "Optically nonlinear materials." Thesis, Cranfield University, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.391585.
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Mayfield, Angela Raye. "Characterization of textile materials by near-infrared relectance spectroscopy." Thesis, Georgia Institute of Technology, 1989. http://hdl.handle.net/1853/8616.
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Salisbury, Brian Eugene. "Mass spectroscopic characterization of small nanoclusters." Diss., Georgia Institute of Technology, 1999. http://hdl.handle.net/1853/30359.
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Narula, Rohit. "Double resonance Raman spectra of graphene : a full 2D calculation." Thesis, Massachusetts Institute of Technology, 2007. http://hdl.handle.net/1721.1/42161.
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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2007.Includes bibliographical references (leaves 85-87).
Visible range Raman spectra of graphene are generated based on the double resonant process employing a full two-dimensional numerical calculation applying second-order perturbation theory. Tight binding expressions for both the TO phonon dispersion and the [pi] - [pi]* electronic bands are used, which are then fit to experimental or ab-initio results. We are able to reproduce the single-peak D mode of graphene at ~ 1380 cm-1 that is identical to experiment. A near linear shift in the D mode peak with changing incoming laser energy of 33 cm-1/eV is calculated. Our shift marginally underestimates the experimental shifts as most of the literature features specimens that contain a few or more layers of graphene through to graphite that ought to subtly alter their electronic and phonon dispersions. However, our approach is readily applicable to such homologous forms of graphene once we have available their electronic band structure and phonon dispersions.
by Rohit Narula.
S.M.
7
Tsagli, Kelvin Xorla. "Temperature Dependence of Photoluminescence Spectra in Polystyrene." University of Akron / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=akron1625744248503334.
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Graham, Daniel J. "Multivariate analysis of TOF-SIMS spectra from self-assembled monolayers /." Thesis, Connect to this title online; UW restricted, 2001. http://hdl.handle.net/1773/8003.
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蘇振強 and Chun-keung So. "Defect study of zinc oxide bulk materials by positron lifetime spectroscopy." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2008. http://hub.hku.hk/bib/B39558691.
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Patrick, Christopher Edward. "Photoemission spectra of nanostructured solar cell interfaces from first principles." Thesis, University of Oxford, 2013. http://ora.ox.ac.uk/objects/uuid:fa2333ea-7016-4d6f-8d55-aee4178482a6.
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Photovoltaic (PV) technologies could provide abundant, clean and secure energy through the conversion of sunlight into electricity, but currently are too expensive to compete with conventional sources of power. Novel PV devices incorporating nanostructured materials, such as the dye-sensitized solar cell (DSC), have been identified as viable, low-cost alternatives to traditional solar cell designs. In spite of technological progress in the field over the last twenty years, the underlying physics governing DSC operation is still not well understood. In this thesis, first-principles (i.e. parameter-free) calculations are performed with the aim of connecting experimentally-measured photoemission data to the underlying atomistic and electronic structure of interfaces found in DSCs. The principal system under study is the interface between anatase titanium dioxide (TiO2) and the "N3" dye molecule, one of the most widely-investigated device designs in DSC research. Atomistic models of the interface are determined within density-functional theory. Core-level spectra of these interface models are then calculated using a ∆SCF approach. Comparison of the calculations to published experimental data finds that intermolecular interactions have a significant effect on the spectra. Next, the electronic structure of bulk TiO2 and of isolated N3 molecules is calculated using the GW approximation and ∆SCF method respectively. For the former, it is shown that including Hubbard U corrections in the initial Hamiltonian reduces the GW gap by 0.4 eV. These calculations are then used to determine the valence photoemission spectrum of the full interface. By including image-charge effects, thermal broadening and configurational disorder, quantitative agreement with experimentally-measured spectra is demonstrated. In addition to the N3/TiO2 system, calculations of the core-level spectra of the interfaces between TiO2 and H2O and bi-isonicotinic acid are also presented. The thesis concludes with a study of the X2Y3/TiO2 interfaces (X=Sb, Bi; Y=S, Se) found in recently-developed semiconductor-sensitized solar cells.
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Nishi, Masayuki. "Studies on 4f-4f transition spectra of trivalent rare-earth ions in oxide materials." 京都大学 (Kyoto University), 2005. http://hdl.handle.net/2433/144882.
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Kilitziraki, Maria. "Evaporated organic films of tetrathiafulvalene and related materials." Thesis, Durham University, 1996. http://etheses.dur.ac.uk/5292/.
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This thesis describes the design, construction and application of a novel vacuum system for the preparation of thin films of organic charge-transfer compounds. The method of thermal evaporation was used for four materials: tetrathiafulvalene (TTF) and three of its derivatives, dimethyltetrathiafiilvalene (DiMe-TTF), trimethyltetrathiafiilvalene (TriMe-TTF) and bis(ethylenedithio)tetrathiafiilvalene (BEDT-TTF). The resulting thin layers were characterised using optical and electron microscopy, infrared/visible spectroscopy and dc conductivity measurements down to 77K.Thin films of tetrathiafulvalene, after doping with iodine, exhibited a maximum value of dc, in-plane room temperature conductivity σ of 8.0+2.4 S cm(^-1). Semiconducting behaviour was exhibited over the range 77-300 K with AE = 0.09+0.02 eV. The effect of the deposition rate on fihn morphology is reported. TTF iodide layers were also prepared by co- evaporating the two components. These films exhibited a maximum conductivity of 2.9+0.4 S cm(^-1) at room temperature. Again, semiconducting behaviour was noted over the range 77- 300 K with AE = 0.2+0.02 eV. A comparison of the optical, structural and electrical properties of the two types of films is made. DiMe-TTF and TriMe-TTF thin films were also successfully prepared. Doping with iodine resulted in in-plane, dc room temperature conductivities of 10(^-6) and 10(^-7) S cm(^-1), respectively. These values, together with data from optical spectroscopy, suggested that both salts were in the full charge-transfer state. (BEDT-TTF) iodide thin films were deposited by evaporating the organic compound and subsequent doping. Doped films possessed a dc, in-plane room temperature conductivity of 10(^-3) S cm(^-1).Annealing these layers at 60ºC resulted in an increase in conductivity with a final value of 1.6 S cm(^-1). Semiconducting behaviour over the range 77-300 K was exhibited by the annealed films (ΔE = 0.028 eV).Finally, thin film transistors, incorporating TTF and BEDT-TTF doped layers, were fabricated and their electrical characteristics measured.
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Doss, Calvin James. "Raman studies of the nanostructure of sol-gel materials." Diss., This resource online, 1994. http://scholar.lib.vt.edu/theses/available/etd-06062008-164932/.
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Harris, Peter John. "Preparation and characterisation of light emitting porous semiconductors." Thesis, De Montfort University, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.391080.
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Zhang, Qi. "The fabrication and characterisation of quantum dots, wires and wire net works." Thesis, De Montfort University, 1996. http://hdl.handle.net/2086/4182.
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Potter, Mark David George. "Luminescence spectroscopy of CdTe/CdS based photovoltaic devices and associated materials." Thesis, Durham University, 2000. http://etheses.dur.ac.uk/4607/.
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This thesis contains primarily a study of CdTe/CdS heterojunction solar cells^ chiefly using photoluminescence spectroscopy. These solar cells show a good potential for commercial power generation in the near Aiture and are of interest to several major companies. A vital but little understood step in the manufacturing process is: annealing the cells in the presence of chlorine prior to back contact application. Studies are performed on a selection of thin film CdTe/CdS cells subjected to CdCl(_2) anneals of different duration. A chemical bevel etch was used to study the spectra at different depths into the sample and laser intensity arid sarhple temperature variations to identify the mechanisms behind the observed photoluminescence peaks. Evidence was found for the CdCl(_2) anneal promoting sulphur diffusion and subsequent grain boundary passivation in the CdTe, leading to increased minority carrier lifetimes and device efficiencies Attempts to obtain electroluminescence from the CdTe/CdS solar cells were madei By using current pulses electroluminescence was obtained in the 780-850nm range with discernible spectral features. Photoluminescence (PL) studies were also performed on a single crystal of CdTe grown to an unprecedented size of approx. 5 cm diameter at Durham university by a multi-tube seeded vapour method of crystal growth. Much higher resolution spectra were: obtained for this than for the solar cells. Several peaks were identified arid the mechanisms responsible were theorised. By taking slices of the crystal boule the PL spectra at different points-throughout the bulk of the crystal were determined. A series of high quality ion-implanted CdTe crystals were also studied! by intensity and temperature dependent PL in order to obtain a better understanding of the effects of known concentrations of known impurities on the PL spectra of CdTe. Specific PL features associated with certain dopants were observed.
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Hardaway, Harvey Royston. "Spectroscopic studies of InAs/InAsSb heterostructure light-emitting diodes for the mid-infrared region." Thesis, Imperial College London, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.322199.
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Simmons, Jed. "OPTICAL AND PHYSICAL PROPERTIES OF CERAMIC CRYSTAL LASER MATERIALS." Doctoral diss., University of Central Florida, 2007. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/4123.
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Historically ceramic crystal laser material has had disadvantages compared to single crystal laser material. However, progress has been made in the last decade and a half to overcome the disadvantages associated with ceramic crystal. Today, because of the promise of ceramic crystal as a high power laser material, investigation into its properties, both physical and optical, is warranted and important. Thermal expansion was measured in this thesis for Nd:YAG (yttrium aluminum garnet) ceramic crystal using an interferometric method. The interferometer employed a spatially filtered HeNe at 633 nm wavelength. Thermal expansion coefficients measured for the ceramic crystal samples were near the reported values for single crystal Nd:YAG. With a similar experimental setup as that for the thermal expansion measurements, dn/dT for ceramic crystal Nd:YAG was measured and found to be slightly higher than the reported value for single crystal. Depolarization loss due to thermal gradient induced stresses can limit laser performance. As a result this phenomenon was modeled for ceramic crystal materials and compared to single crystals for slab and rod shaped gain media. This was accomplished using COMSOL Multiphysics, and MATLAB. Results indicate a dependence of the depolarization loss on the grain size where the loss decreases with decreased grain size even to the point where lower loss may be expected in ceramic crystals than in single crystal samples when the grain sizes in the ceramic crystal are sufficiently small. Deformation-induced thermal lensing was modeled for a single crystal slab and its relevance to ceramic crystal is discussed. Data indicates the most notable cause of deformation-induced thermal lensing is a consequence of the deformation of the top and bottom surfaces. Also, the strength of the lensing along the thickness is greater than the width and greater than that due to other causes of lensing along the thickness of the slab. Emission spectra, absorption spectra, and fluorescence lifetime were measured for Nd:YAG ceramic crystal and Yb:Lu2O3 ceramic crystal. No apparent inhomogeneous broadening appears to exist in the Nd:YAG ceramic at low concentrations. Concentration and temperature dependence effects on emission spectra were measured and are presented. Laser action in a thin disk of Yb:Y2O3 ceramic crystal was achieved. Pumping was accomplished with a fiber coupled diode laser stack at 938 nm. A slope efficiency of 34% was achieved with maximum output energy of 28.8 mJ/pulse.Ph.D.
Department of Physics
Sciences
Physics PhD
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Parkinson, Mark. "Structural and optical properties in porous nanostructured semiconductors." Thesis, De Montfort University, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.391476.
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Pike, Kevin John. "An NMR study of some low-dimensional magnetically correlated materials." Thesis, University of Warwick, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.344004.
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Townsley, Christopher Mark. "Optical spectroscopy of two-dimensional hole systems in the quantum limit." Thesis, University of Exeter, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.312067.
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Andersson, Edvin. "Spectroelectrochemical analysis of the Li-ion battery solid electrolyte interphase using simulated Raman spectra." Thesis, Uppsala universitet, Fasta tillståndets fysik, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-413474.
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Lithium Ion Batteries (LIBs) are important in today's society, powering cars and mobile devices. LIBs consist of a negative anode commonly made of graphite, and a positive cathode commonly made from transition metal oxides. Between these electrodes are separators and organic solvent based electrolyte. Due to the high potential of LIBs the electrolyte is reduced at the anode. The electrolyte reduction results in the formation of a layer called the Solid Electrolyte Interphase (SEI), which prohibits the further breakdown of the electrolyte. Despite being researched for over50 years, the composition formation of the SEI is still poorly understood. The aim of this project is to develop strategies for efficient identification and classification of various active and intermediate components in the SEI, to, in turn, gain an understanding of the reactions taking place, which will help find routes to stabilize and tailor the composition of the SEI layer for long-term stability and optimal battery performance. For a model gold/li-ion battery electrolyte system, Raman spectra will be obtained using Surface Enhanced Raman Spectroscopy (SERS) in a spectroelectrochemical application where the voltage of the working gold electrode is swept from high to low potentials. Spectra of common components of the SEI as well as similar compounds will be simulated using Density Functional Theory (DFT). The DFT data is also used to calculate the spontaneity of reactions speculated to form the SEI. The simulated data will be validated by comparing it to experimental spectra from pure substances. The spectroelectrochemical SERS results show a clear formation of Li-carbonate at the SERS substrate, as well as the decomposition of the electrolyte into other species, according to the simulated data. It is however shown that there are several issues when modelling spectra, that makes it harder to correlate the simulated spectra with the spectroelectrochemical spectra. These issues include limited knowledge of the structure of the compounds thought to form on the anode surface, and incorrect choices in simulational parameters. To solve these issues, more work is needed in these areas, and the spectroelectrochemical methods used in this thesis needs to be combined with other experimental methods to narrow down the amount of compounds to be modelled. More work is also needed to avoid impurities in the electrolyte. Impurities leads to a thick inorganic layer which prohibits the observation of species in the organic layer.
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LEBRAO, GUILHERME W. "Processamento e caracterização de material compósito polimérico obtido com nanotubo de carbono funcionalizado." reponame:Repositório Institucional do IPEN, 2013. http://repositorio.ipen.br:8080/xmlui/handle/123456789/23595.
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Tese (Doutorado em Tecnologia Nuclear)
IPEN/T
Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP
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Flores, Livas José. "Computational and experimental studies of sp3-materials at high pressure." Thesis, Lyon 1, 2012. http://www.theses.fr/2012LYO10127.
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Nous présentons des études expérimentales et théoriques de disiliciures alcalino-terreux, le disilane (Si2H6) et du carbone à haute pression. Nous étudions les disiliciures et en particulier le cas d’une phase plane de BaSI2 qui a une structure hexagonale avec des liaisons sp3 entre les atomes de silicium. Cet environnement électronique conduit à un gaufrage de feuilles du silicium. Nous démontrons alors une amélioration de la température de transition supraconductrice de 6 à 8.9 K lorsque les couches de silicium s’aplanissent dans cette structure. Des calculs ab initio basés sur DFT ont guidé la recherche expérimentale et permettent d’expliquer comment les propriétés électroniques et des phonons sont fortement affectés par les fluctuations du flambage des plans de silicium. Nous avons aussi étudié les phases cristallines de disilane à très haute pression et une nouvelle phase métallique est proposé en utilisant les méthodes de prédiction de structure cristalline. Les températures de transition calculées donnant un supraconducteur autour de 20 K à 100 GPa. Ces valeurs sont significativement plus faibles comparées à celles avancées dans la littérature. Finalement, nous présentons des études de structures de carbone à haute pression à travers une recherche de structure systématique. Nous avons trouvé une nouvelle forme allotropique du carbone avec une symétrie Cmmm que nous appelons Z-carbone. Cette phase est prévue pour être plus stable que le graphite pour des pressions supérieures à 10 GPa. Des expériences et simulation de rayon-X et spectre Raman sugèrent l’existence de Z-carbone dans des micro-domaines de graphite sous pressionWe present experimental and theoretical studies of sp3 materials, alkaline-earth-metal (AEM) disilicides, disilane (Si2H6) and carbon at high pressure. First, we study the AEM disilicides and in particular the case of a layered phase of BaSi2 which has an hexagonal structure with sp3 bonding of the silicon atoms. This electronic environment leads to a natural corrugated Si-sheets. Extensive ab initio calculations based on DFT guided the experimental research and permit explain how electronic and phonon properties are strongly affected by changes in the buckling of the silicon plans. We demonstrate experimentally and theoretically an enhancement of superconducting transition temperatures from 6 to 8.9 K when silicon planes flatten out in this structure. Second, we investigated the crystal phases of disilane at the megabar range of pressure. A novel metallic phase of disilane is proposed by using crystal structure prediction methods. The calculated transition temperatures yielding a superconducting Tc of around 20 K at 100 GPa and decreasing to 13 K at 220 GPa. These values are significantly smaller than previously predicted Tc’s and put serious drawbacks in the possibility of high-Tc superconductivity based on silicon-hydrogen systems. Third, we studied the sp3-carbon structures at high pressure through a systematic structure search. We found a new allotrope of carbon with Cmmm symmetry which we refer to as Z-carbon. This phase is predicted to be more stable than graphite for pressures above 10 GPa and is formed by sp3-bonds. Experimental and simulated XRD, Raman spectra suggest the existence of Z-carbon in micro-domains of graphite under pressure
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Blay, Claire. "Characterisation of intermixed quantum well material by measurements of spontaneous emission." Thesis, University of Bath, 2000. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.323571.
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MACHADO, GLAUSON A. F. "Desenvolvimento de composito ceramico a partir de mistura de alumina e polimero pecursor ceramico polissilsesquioxano." reponame:Repositório Institucional do IPEN, 2009. http://repositorio.ipen.br:8080/xmlui/handle/123456789/9432.
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Dissertacao (Mestrado)
IPEN/D
Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP
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Starovoytov, Artem. "Steps towards silicon optoelectronics." Thesis, De Montfort University, 1999. http://hdl.handle.net/2086/10699.
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This thesis addresses the issue of a potential future microelectronics technology, namely the possibility of utilising the optical properties of nanocrystalline silicon for optoelectronic circuits. The subject is subdivided into three chapters. Chapter 1 is an introduction. It formulates the oncoming problem for microelectronic development, explains the basics of Integrated Optoelectronics, introduces porous silicon as a new light-emitting material and gives a brief review of other competing light-emitting material systems currently under investigation. Examples of existing porous silicon devices are given. Chapter 2 reviews the basic physics relevant to the subject of this thesis and informs on the present situation in this field of research, including both experimental and theoretical knowledge gained up-to-date. The chapter provides the necessary background for correct interpretation of the results reported in Chapter 3 and for a realistic decision on the direction for future work. Chapter 3 describes my own experimental and computational results within the framework of the subject, obtained at De Montfort University. These include: onestep preparation of laterally structured porous silicon with photoluminescence and microscopy characterisation, Raman spectroscopy of porous silicon, a polarisation study of the photoluminescence from porous silicon, computer simulations of the conductivity of two-component media and of laser focused atomic deposition for nanostructure fabrication. Thus, this thesis makes a dual contribution to the chosen field: it summarises the present knowledge on the possibility of utilising optical properties of nanocrystalline silicon in silicon-based electronics, and it reports new results within the framework of the subject. The main conclusion is that due to its promising optoelectronic properties nanocrystalline silicon remains a prospective competitor for the cheapest and fastest microelectronics of the next century.
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Herrenbrück, Martin Johannes [Verfasser], Roman [Akademischer Betreuer] Lackner, and Fabian [Akademischer Betreuer] Duddeck. "Finite-Element Based Determination of Response Spectra of Viscoelastic Materials Subjected to Low-Velocity Impact Loading / Martin Johannes Herrenbrück. Gutachter: Roman Lackner ; Fabian Duddeck. Betreuer: Roman Lackner." München : Universitätsbibliothek der TU München, 2013. http://d-nb.info/1043587640/34.
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Bouldi, Nadejda. "Theory of X-ray circular dichroism and application to materials under pressure." Thesis, Paris 6, 2017. http://www.theses.fr/2017PA066491/document.
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Le but principal de cette thèse était de calculer les spectres de dichroïsme circulaire magnétique de rayons~X au seuil K afin de fournir un outil pour interpréter les spectres expérimentaux, jusqu'ici très déroutants. La détermination du dichroïsme circulaire nécessite le calcul précis des spectres d'absorption des rayons~X polarisés circulairement. Nous avons constaté que la théorie des perturbations semi-classique dépendante du temps, communément utilisée pour calculer les sections efficaces d'absorption et de diffusion, est incompatible à la fois, avec l'invariance de jauge et avec les descriptions semi-relativistes de la dynamique des électrons. Pour résoudre ces problèmes, on applique une transformation de Foldy-Wouthuysen aux sections efficaces relativistes données par l'électrodynamique quantique. Ainsi, un nouveau terme d'interaction lumière-matière émerge, que nous avons appelé "spin-position". Une approche performante a été développée pour calculer la section efficace d'absorption afin d'obtenir le dichroïsme circulaire magnétique de rayons~X (XMCD) et le dichroïsme circulaire naturel de rayons~X (XNCD). La méthode numérique repose sur la théorie de la fonctionnelle de la densité en ondes planes avec des pseudopotentiels. Nous constatons que le terme couplant l'opérateur dipolaire électrique avec l'opérateur spin-position contribue significativement au XMCD au seuil K du fer, du nickel et du cobalt ferromagnétiques et nous l'expliquons grâce aux règles de somme. Nous avons également appliqué la méthode aux calculs du XMCD dans FeH et CrO2. Dans les deux cas, la combinaison de l'expérience et de la théorie conduit à un enrichissement mutuelThe main purpose of this thesis was to compute X-ray magnetic circular dichroism spectra at the K-edge in order to provide a tool to interpret the, so far very puzzling, experimental spectra. Computation of circular dichroism requires precise calculations of X-ray absorption spectra (XAS) for circularly polarized light. We have found that there is an incompatibility of the semi-classical time-dependent perturbation theory commonly used to calculate light absorption and scattering cross-sections with both gauge invariance and semi-relativistic descriptions of the electron dynamics. The problems are solved by applying a Foldy-Wouthuysen transformation to the fully relativistic cross-sections given by quantum electrodynamics. In the process, a new light-matter interaction term emerges, that we named the "spin-position" interaction. An efficient first-principles approach was developed to compute the absorption cross-section in order to obtain X-ray magnetic circular dichroism (XMCD) and X-ray natural circular dichroism (XNCD). The numerical method relies on density-functional theory with plane waves and pseudopotentials. We find that the term coupling the electric dipole operator with the spin-position operator contributes significantly to the XMCD at the K-edge of ferromagnetic iron, cobalt, and nickel. We obtain a sum rule relating this term to the spin magnetic moment of the p states. We also applied the method to calculations of K-edge XMCD in FeH and CrO2. In both cases, the combination of experiment and theory leads to mutual enrichment
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Locht, Inka L. M. "Theoretical methods for the electronic structure and magnetism of strongly correlated materials." Doctoral thesis, Uppsala universitet, Materialteori, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-308699.
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In this work we study the interesting physics of the rare earths, and the microscopic state after ultrafast magnetization dynamics in iron. Moreover, this work covers the development, examination and application of several methods used in solid state physics. The first and the last part are related to strongly correlated electrons. The second part is related to the field of ultrafast magnetization dynamics. In the first part we apply density functional theory plus dynamical mean field theory within the Hubbard I approximation to describe the interesting physics of the rare-earth metals. These elements are characterized by the localized nature of the 4f electrons and the itinerant character of the other valence electrons. We calculate a wide range of properties of the rare-earth metals and find a good correspondence with experimental data. We argue that this theory can be the basis of future investigations addressing rare-earth based materials in general. In the second part of this thesis we develop a model, based on statistical arguments, to predict the microscopic state after ultrafast magnetization dynamics in iron. We predict that the microscopic state after ultrafast demagnetization is qualitatively different from the state after ultrafast increase of magnetization. This prediction is supported by previously published spectra obtained in magneto-optical experiments. Our model makes it possible to compare the measured data to results that are calculated from microscopic properties. We also investigate the relation between the magnetic asymmetry and the magnetization. In the last part of this work we examine several methods of analytic continuation that are used in many-body physics to obtain physical quantities on real energies from either imaginary time or Matsubara frequency data. In particular, we improve the Padé approximant method of analytic continuation. We compare the reliability and performance of this and other methods for both one and two-particle Green's functions. We also investigate the advantages of implementing a method of analytic continuation based on stochastic sampling on a graphics processing unit (GPU).
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Bahukudumbi, Pradipkumar. "Energy landscape and electric field mediated interfacial colloidal assembly." Texas A&M University, 2003. http://hdl.handle.net/1969.1/5883.
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Chemically and physically patterned surfaces can be used as templates to guide
nano- and micro- scale particle assembly, but the design is often limited by an inability
to sufficiently characterize how pattern features influence local particle-surface
interactions on the order of thermal energy, kT. The research outlined in this dissertation
describes comprehensive optical microscopy (i.e. evanescent wave, video)
measurements and analyses of many-body and multi-dimensional interactions, dynamics
and structure in inhomogeneous colloidal fluid systems. In particular, I demonstrate
how non-intrusive observation of an ensemble of particles diffusing past each other and
over a physically patterned surface topography can be used to obtain sensitive images of
energy landscape features. I also link diffusing colloidal probe dynamics to energy
landscape features, which is important for understanding the temporal imaging process
and self-assembly kinetics. A complementary effort in this dissertation investigated the
use of external AC electric fields to reversibly tune colloidal interactions to produce
metastable ordered configurations. In addition, the electrical impedance spectra associated with colloidal assemblies formed between interfacial microelectrode gaps was
measured and consistently modelled using representative equivalent circuits.
Significant results from this dissertation include the synergistic use of the very
same colloids as both imaging probes and building blocks in feedback controlled selfassembly
on patterns. Cycling the AC field frequencies was found to be an effective
way to anneal equilibrium colloidal configurations. Quantitative predictions of
dominant transport mechanisms as a function of AC electric field amplitude and
frequency were able to consistently explain the steady-state colloidal microstructures
formed within electrode gaps observed using video microscopy. A functional electrical
switch using gold nanoparticles was realized by reversibly forming and breaking
colloidal wires between electrode gaps. Extension of the concepts developed in this
dissertation suggest a general strategy to engineer the assembly of colloidal particles into
ordered materials and controllable devices that provide the basis for numerous
emerging technologies (e.g. photonic crystals, nanowires, reconfigurable antennas,
biomimetic materials).
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PEREIRA, MARCO A. G. "Avaliacao dos espectros primarios e secundarios da radiacao X em objetos simuladores para energias utilizadas em diagnostico medico." reponame:Repositório Institucional do IPEN, 2004. http://repositorio.ipen.br:8080/xmlui/handle/123456789/11241.
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Tese (Doutoramento)
IPEN/T
Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP
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Chen, Ping. "Intermediate phases, boson and floppy modes, and demixing of network structures of binary As-S and As-Se glasses." University of Cincinnati / OhioLINK, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1250689099.
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Dhuvad, Pratikkumar. "FIRST-PRINCIPLES STUDIES OF FERROELECTRIC PROPERTIES IN ORGANIC CRYSTAL AND PEROVSKITE SUPERLATTICES." Diss., Temple University Libraries, 2018. http://cdm16002.contentdm.oclc.org/cdm/ref/collection/p245801coll10/id/524696.
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PhysicsPh.D.
This thesis discusses structural and ferroelectric properties of two well-known classes of materials, perovskite oxides and Hydrogen bonded ferroelectrics, using first-principles calculations. Certain aspects of first principles calculations are central to the problems presented in this thesis. Such as the ability to calculate polarization based on the modern theory of polarization and calculation of ferroelectric property under finite electric displacement field. Therefore, these fundamental theoretical approaches are discussed following an opening section on the basic methodology of density-functional theory. In addition to the discussion on theoretical methods, a brief review of different phenomena and techniques crucial to alter/enhance ferroelectric properties at the interfaces of perovskite materials has been presented along with examples. The first problem presented in this thesis proposes and validates an alternative quantitative measure of ferroelectric(FE) and antiferrodistortive(AFD) instabilities by means of calculating inverse capacitance and layer inverse capacitance of layered perovskites. The presented methodological approach is applied to BaTiO$_{3}$/CaTiO$_{3}$ and PbTiO$_{3}$/SrTiO$_{3}$ superlattices and it precisely estimates FE and AFD instabilities. Here we also present an approach to accurately predict the ferroelectric instabilities in large period superlattices from the statistical coefficients obtained from short period superlattices. In the second problem, we study ferroelectricity in an organic crystal(croconic acid) for which ferroelectric polarization is close to that of bulk BaTiO$_{3}$. We employ new meta-GGA functional named SCAN and revisit all structural and ferroelectric properties. Calculated X-ray absorption spectra(XAS) qualitatively and quantitatively agrees well with experimental O K-edge spectra. By discussing the origin of each XAS peak and their characteristic we demonstrate with a systematic approach the connection between ferroelectricity and XAS in croconic acid. Best to our knowledge such relation has not been realized in past. This study could prove XAS as a new way to measure ferroelectric instability in hydrogen-bonded organic ferroelectrics.
Temple University--Theses
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LIBRANTZ, ANDRE F. H. "Investigacao dos processos de excitacao multifotonica da configuracao 4fsup(2)5d nos cristais de LiYFsub(4), LuLiFsub(4) e BaYsub(2)Fsub(8) dopados com neodimio trivalente." reponame:Repositório Institucional do IPEN, 2004. http://repositorio.ipen.br:8080/xmlui/handle/123456789/11202.
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Tese (Doutoramento)
IPEN/T
Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP
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Cannon, Robert William. "Automated Spectral Identification of Materials using Spectral Identity Mapping." Cleveland State University / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=csu1377031729.
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Ünal, Bayram. "Optical, electrical and structural properties of nanostructured silicon and silicon-germanium alloys." Thesis, De Montfort University, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.391480.
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Fernandes, Catarina. "Spectral studies of extra-terrestrial materials." Thesis, Open University, 2012. http://oro.open.ac.uk/54694/.
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Experiments were made using a state-of-the-art UV-Vis microspectrophotometer (MSP) in order to assess if the instrument is suitable for use on spectroscopy of terrestrial and extra-terrestrial materials. This new instrument brings advantages that cannot be found in instruments currently in use: it requires only extremely small samples (min of -2 um) and it is very quick to use (little sample preparation and spectra taken in less than 2 min). If suitable, the instrument could help to show the relationship between meteorites and their parent bodies and in the study ' of very small fragile samples, such as cometary samples and Interplanetary Dust Particles (IDPs). Using samples of minerals commonly found in meteorites, it was concluded that the instrument is suitable for the study of these materials, however it has some limitations and certain conditions need to be met. The method was then applied on two grains from comet 81P/Wild 2 returned by the space mission Stardust. Further limitations were found with these samples caused by the fact that they are covered in aerogel and embedded in gold foil. Results indicate however, that the samples seem to be composed of a mixture of different materials. Results from the study of HED (howardites, eucrites and diogenites) type meteorites proved that if the conditions are met, the technique is suitable and comparable to other instruments and can be used to match the spectra of meteorites to that of their possible asteroidal parent bodies. A complementary investigation studied the effects of impact by shock on the spectra of rocks using a Light Gas Gun and Near Infrared spectroscopy with the goal of investigating the effects of weathering on the spectra of asteroids. It was found that there is a change in the spectra of the samples and a relationship with a change in composition of the impacted area.
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MARCHINI, LEONARDO G. "Desenvolvimento de marcador óptico para processamento de poliolefinas." reponame:Repositório Institucional do IPEN, 2013. http://repositorio.ipen.br:8080/xmlui/handle/123456789/10193.
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Dissertação (Mestrado)
IPEN/D
Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP
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MOURA, ESPERIDIANA A. B. de. "Avaliação do desempenho de embalagens para alimentos quando submetidas a tratamento por radiação ionizante." reponame:Repositório Institucional do IPEN, 2006. http://repositorio.ipen.br:8080/xmlui/handle/123456789/11427.
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Tese (Doutoramento)
IPEN/T
Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP
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Olszak, Peter D. "Nonlinear absorption and free carrier recombination in direct gap semiconductors." Doctoral diss., University of Central Florida, 2010. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/4620.
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Nonlinear absorption of Indium Antimonide (InSb) has been studied for many years, yet due to the complexity of absorption mechanisms and experimental difficulties in the infrared, this is still a subject of research. Although measurements have been made in the past, a consistent model that worked for both picosecond and nanosecond pulse widths had not been demonstrated. In this project, temperature dependent two-photon (2PA) and free carrier absorption (FCA) spectra of InSb are measured using femtosecond, picosecond, and nanosecond IR sources. The 2PA spectrum is measured at room temperature with femtosecond pulses, and the temperature dependence of 2PA and FCA is measured at 10.6[micro]meters using a nanosecond CO[sub]2 laser giving results consistent with the temperature dependent measurements at several wavelengths made with a tunable picosecond system. Measurements over this substantial range of pulse widths give results for FCA and 2PA consistent with a recent theoretical model for FCA. While the FCA cross section has been generally accepted in the past to be a constant for the temperatures and wavelengths used in this study, this model predicts that it varies significantly with temperature as well as wavelength. Additionally, the results for 2PA are consistent with the band gap scaling (Eg[super]-3) predicted by a simple two parabolic band model. Using nanosecond pulses from a CO?éé laser enables the recombination rates to be determined through nonlinear transmittance measurements. Three-photon absorption is also observed in InSb for photon energies below the 2PA band edge. Prior to this work, data on three-photon absorption (3PA) in semiconductors was scarce and most experiments were performed over narrow spectral ranges, making comparison to the available theoretical models difficult. There was also disagreement between the theoretical results generated by different models, primarily in the spectral behavior.; Therefore, we studied the band gap scaling and spectra of 3PA in several semiconductors by the Z-scan technique. The 3PA coefficient is found to vary as (Eg[super]-7), as predicted by the scaling rules of simple two parabolic band models. The spectral behavior, which is considerably more complex than for 2PA, is found to agree well with a recently published theory based on a four-band model.ID: 029050684; System requirements: World Wide Web browser and PDF reader.; Mode of access: World Wide Web.; Thesis (Ph.D.)--University of Central Florida, 2010.; Includes bibliographical references.
Ph.D.
Doctorate
Optics and Photonics
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Ratnaparkhe, Amol. "FIRST PRINCIPLES STUDY OF ELECTRONIC ANDVIBRATIONAL PROPERTIES OF WIDE BAND GAPOXIDE AND NITRIDE SEMICONDUCTORS." Case Western Reserve University School of Graduate Studies / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=case1619606222502271.
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Domènech, i. Amador Núria. "Phonons in III-nitride thinfilms, bulk and nanowires: a closer look into InN vibrational properties." Doctoral thesis, Universitat de Barcelona, 2015. http://hdl.handle.net/10803/348867.
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This thesis is devoted to the study of the interactions of phonons in indium nitride (InN) and materials of the (In,Ga)N system with wurtzite structure. For this purpose, we present Raman spectroscopy on nanowires (NWs), thin films and bulk samples, in order to adress phonon interactions in these materials. We also present Brillouin spectrsocopy measurements of InN thin films, from which a reliable set of elastic constants is proposed.
We have studied the phonon anharmonic interactions and phonon decay channels of InN, both in thin films and NWs. The temperature dependence of Raman peak width of all the phonon modes has been studied using a model that considers the contribution of three- and four-phonon processes, taking into account the phonon density of states obtained by ab-initio calculations.
In InN thin films, we find that the E2h phonon mode mainly decays through 4-phonon processes, whereas the extremely narrow E2l mode can decay only through up-conversion processes. The LO and the TO modes are found to decay through 3-phonon and 4-phonon interactions. In InN NWs we found the same phonon decay channels but phonon linewidths are significantly reduced, indicating a higher crystalline quality. The lifetimes of the phonon modes are derived from the measured phonon linewidths. The long-lived E2l phonon exhibits the largest lifetime, which is mainly limited by impurity scattering. We also study the anharmonic decay of high-frequency LVMs H complexes in Mg-doped InN, which can be explained by considering dephasing due to quasi-elastic acoustic phonon scattering.
We have discussed the relevant electronic resonances that affect Raman scattering in the (In,Ga)N system. We show that the optical excitation of the longitudinal optical modes in InN occurs via the Martin's double resonance both in InN layers and nanostructures, even though the defect density of the latter is significantly lower. By performing wavelength-dependent measurements on InN thin films and NWs, the A1(LO) and the E1(LO) wave-vector dispersion close to zone-center have been obtained. We have also studied the impurity-mediated cascade mechanism of multiphonons in InGaN layers. To ascertain the role of the impurities we have studied as-grown samples in comparison with He+-implanted InGaN layers. UV Raman-scattering measurements allow us to measure up to fifth order multiphonon scattering due to cascade mechanism. Relative multiphonon intensities depend on the indium concentration and implantation dose.
Finally, we have studied the LO-Phonon-Plasmon Coupled Modes (LOPCMs) in InN and GaN using the Lindhard-Mermin model. We have determined the electron density in undoped, Si-doped and Mg-doped NWs. We have also studied a bulk, ammonothermally-grown Si-doped GaN sample. No evidence of LOPCMs was detected in the Ga-polar face, probably due to the higher defect density existing in this sample sector. We have detected both branches of the LOPCMs in the N-polar face, and we have made a study of the distribution of the free charge density by means of confocal micro-Raman measurements.Aquesta tesi està dedicada a l’estudi de les interaccions dels fonons en nitrur d'indi (InN) i en semiconductors del sistema (In.Ga)N amb estructura wurtzita. Amb aquest objectiu es presenten estudis d'espectroscòpia Raman en capes primes, nanofils (NWs), i mostres bulk, que han permès abordar de manera global les interaccions dels fonons en aquests materials. Hem estudiat les interaccions anharmòniques i els canals de decaïment dels fonons de InN, tant en capes primes com en NWs. La dependència de l’amplada del pic Raman amb la temperatura de tots els modes fonònics s’ha estudiat utilitzant un model anharmònic que considera la contribució dels processos de tres i quatre fonons, i tenint en compte la densitat d'estats de fonons obtinguda mitjançant càlculs ab-initio. L'anàlisi dels temps de vida fonònics i de la dependència amb temperatura de les freqüències permet afirmar que els NWs tenen una estructura més relaxada que les capes primes. També hem estudiat el decaïment anharmònic de modes locals de vibració corresponents a complexos d'H en InN fortament dopat amb Mg. Hem estudiat les ressonàncies en el sistema (In,Ga)N i la influència de la densitat d’impureses en l’eficiència dels mecanismes ressonants. Hem demostrat que la dispersió Raman de modes òptics longitudinals en el InN es produeix a través de la doble ressonància del Martin tant en capes primer com en nanoestructures, tot i que la densitat de defectes d'aquestes últimes és significativament menor. Hem estudiat també el mecanisme de cascada mediat per impureses, a través del qual es produeix la dispersió de multifonons, en capes primes de InGaN amb diferent composició i diferent grau d’implantació d'ions d'He, i hem comprovat que les intensitats relatives dels multifonons depenen de la concentració d’indi i de la dosi de la implantació. Finalment, hem estudiat l’acoblament de fonons polars amb els plasmons mitjançant el model dielèctric de Lindhard-Mermin, amb la finalitat d’investigar la densitat d’electrons lliures utilitzant espectroscòpia Raman. Hem determinat la concentració d'electrons en NWs de InN sense dopar, dopats amb Si i dopats amb Mg. També hem fet un estudi de la distribució de la densitat de càrrega en una mostra de GaN ammonotermal mitjançant mesures de micro-Raman confocal.
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CUNHA, TATIANA F. da. "Aplicação do poli(epsilon-caprolactona) com estrutura estrelada para obtenção de microesferas biorreabsorvíveis." reponame:Repositório Institucional do IPEN, 2012. http://repositorio.ipen.br:8080/xmlui/handle/123456789/10544.
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IPEN/D
Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP
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Åkerlind, Christina. "Optical Studies of Materials for Spectral Design." Licentiate thesis, Linköpings universitet, Tillämpad optik, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-115369.
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Optical material properties have been studied in a wide wavelength range. Theaim is future use of spectral design for camou age. The main characterization techniques used in this work are Refection Spectroscopy, Scatterometry (BRDF) and Mueller Matrix Ellipsometry. Six camouflage evaluation criteria based on reflection, emissivity, polarization, gloss, dynamic coloring and broadband properties, are to a greater or lesser degree related to the interaction between light and materia. Almost all are connected to the work of this thesis and are exemplied through dierent material categories with potential for use in camouföage applications. The included papers presents: a broad band (visible-infrared-microwave) study, two examples of dynamic optical properties of thin lms, and polarization and scattering properties of a natural surface.
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Quiroga, Jean-Manuel. "Étude des propriétés optiques de multicouches a-Si:H/a-SiO2." Grenoble 1, 1998. http://www.theses.fr/1998GRE10124.
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L'etude porte sur les proprietes optiques de puits nanometriques multiples a-si:h/a-sio#2 elabores par pecvd (he+sih#4+o#2). Les caracteristiques des materiaux de reference sont determinees par diverses techniques de spectroscopie optique. Nous montrons la necessite de simuler les spectres en tenant compte des reflexions multiples afin d'eviter des erreurs importantes sur la valeur du coefficient d'absorption. Des mesures in situ de la teneur en oxygene dans le plasma nous ont permis de determiner une procedure de depot des multicouches reduisant la largeur des interfaces. La modulation de la composition chimique dans l'epaisseur est observee par des mesures de met, de rayons x et de spectrometrie infrarouge. La simulation des spectres de transmission infrarouge de la multicouche consideree comme un milieu effectif montre que l'interface a-sio#2/a-si:h est la plus large. La variation de l'epaisseur des motifs pour des series de multicouches de largeur de puits (d#a#-#s#i#:#h) ou de barriere constante permet d'elaborer des profils-modele de la composition d'oxygene en epaisseur x(d) en tenant compte de la reduction de la couche de silice et de l'oxydation de celle du silicium amorphe par le plasma lors du depot des couches ulterieures. Nous presentons enfin les mesures d'absorption et de photoluminescence des multicouches. La reduction de la largeur du puits conduit a une augmentation apparente du gap (e#g) mais une analyse plus fine s'appuyant sur le modele physico-chimique montre que la valeur apparente de e#g ne correspond pas a la separation minimale entre les bandes de valence et de conduction. Une emission de lumiere visible a l'il a temperature ambiante est observee pour des largeurs de puits nominales inferieures a 20a. Contrairement aux predictions du modele de confinement quantique, la position du pic de photoluminescence est independante de d#a#-#s#i#:#h. Nous concluons que la presence de sous-oxydes au fond du puits est a l'origine de l'emission observee.
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Williamson, Veta Anne. "Investigation of infrared spectral absorptivity of polymeric materials." Thesis, Georgia Institute of Technology, 1994. http://hdl.handle.net/1853/8705.
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Hawkins, Gary J. "Spectral characterisation of infrared optical materials and filters." Thesis, University of Reading, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.285964.
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The optical and semiconductor properties of the materials used in the design and manufacture of infrared interference filters play a vital role in defining the spectral performance achievable from a multilayer filter design. This thesis examines the theoretical basis of the behaviour of absorptive and dispersive mechanisms in optical materials and derives methods of determining values for their complex optical constants. By applying these properties to the multilayer filter design, a predictive model for the filter performance has been constructed to determine if a chosen design can achieve the specified spectral performance requirements, prior to manufacture. Examples are given demonstrating the convergence of prediction with practice. This predictive model approach has then been expanded to develop a method for determining the spectral design requirements for the individual filters and coatings integrated into an atmospheric radiometer instrument. This process uses an integrated systems approach, by which the characteristics of all the contributing elements provide a predicted spectral model of the instrument. By then applying reverse synthesis to this model, the particular spectral requirements of the individual filters can be determined. Examples are given of particular spectral design requirements for filters derived using this method. The effects of the space environment on the spectral and physical properties of infrared filters and materials is also presented. This includes a description of the radiation environments to which filters are subjected in low Earth orbit. A quantitative analysis of the effects of this environment on the spectral characteristics of exposed filters and materials is made, together with an assessment of the physical degradation mechanisms that affect filter performance.
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McCrindle, Iain James Hugh. "Structured photonic materials for multi-spectral imaging applications." Thesis, University of Glasgow, 2015. http://theses.gla.ac.uk/6446/.
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Structured photonic materials are typically composed of periodic subwavelength elements where the unit cell geometries can impact the overall optical characteristics of the bulk material. By using micro and nanofabrication technologies it is possible to engineer the electromagnetic properties of structured photonic materials for a given application and create a variety of optical components such as band pass filters and absorbers. Two structured photonic materials that have gained substantial interest in recent years are plasmonic filters and metamaterials which are well suited for optical and terahertz imaging applications, respectively. In addition to imaging applications within individual wavebands, structured photonic materials, such as plasmonic filters and metamaterials, could be hybridised and combined with suitable sensors to create a multi-spectral imaging system capable of imaging at optical and terahertz wavebands simultaneously. These new hybrid structured photonic materials are known as synthetic multi-spectral materials, and their development will be presented in this work. To design synthetic multi-spectral materials it was necessary to optimise the plasmonic filter and metamaterial components independently. This involved electromagnetic simulation studies using finite-difference time-domain techniques, fabrication of the structured materials and characterisation using suitable techniques for the relevant spectral band. It was also necessary to ensure that all structures used the same materials and similar fabrication processing techniques as a means of simplifying hybridisation of the two structures. Plasmonic filters exhibit extraordinary optical transmission due to coupling of light with surface plasmons at a metal-dielectric interface. A 16 colour plasmonic filter set, consisting of triangular hole arrays etched into an aluminium film, was optimised for imaging applications in the visible and near infrared spectral range. Initial work on the integration of synthetic multi-spectral materials with CMOS image sensors was undertaken by developing fabrication processes to integrate plasmonic colour filters with two different CMOS chips. Preliminary results from the characterisation of the optical filters fabricated on to the chips have been presented. The resonant wavelengths of the plasmonic colour filters were then scaled up to infrared wavelengths where it was necessary to consider the role of spoof surface plasmons on the extraordinary optical transmission phenomenon. This led to the fabrication of 8 short wave infrared plasmonic filters. Metamaterial band pass filters consist of a single metal film etched with a periodic complementary electric ring resonator unit cell structure. Metamaterial absorbers consist of an electric ring resonator, separated by a metallic ground layer by a dielectric spacer. In the course of this work, two metamaterial filters and four metamaterial absorbers were designed. The metamaterial structures exhibit resonant characteristics at terahertz frequencies. Three synthetic multi-spectral materials, each consisting of hybrid plasmonic filter and terahertz metamaterial structures, have been simulated, fabricated and characterised. The first synthetic multi-spectral material combines 16 plasmonic filters with a terahertz metamaterial filter and is capable of filtering 15 optical wavelengths and a single near infrared wavelength, whilst simultaneously filtering a single terahertz frequency. The multi-spectral filter demonstrates that it is possible to engineer the optical passband characteristics of a thin metal film over several decades of wavelength using a single electron beam lithography step. The second synthetic multi-spectral material consists of 16 plasmonic filters hybridised with a terahertz metamaterial absorber and can filter 15 optical wavelengths and a single near infrared wavelength whilst simultaneously absorbing a single terahertz frequency. Plasmonic filters and metamaterial absorbers are promising components for use in the development of new optical and terahertz imaging systems, respectively, and therefore the second synthetic multi-spectral material represents a significant step forward in the development of a visible and terahertz multi-spectral camera. The third synthetic multi-spectral material combines 7 plasmonic filters with a low metal fill factor metamaterial absorber, to increase the measured transmission of the plasmonic filter components. The third synthetic multi-spectral material is capable of filtering three optical wavelengths, a single near infrared wavelength, a single short wave infrared wavelength and two mid infrared wavelengths, whilst simultaneously absorbing a single terahertz frequency. Such a synthetic multi-spectral material could aid in the development of a visible, infrared and terahertz multi-spectral camera.
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Acharya, Krishna Prasad. "Photocurrent Spectroscopy of CdS/Plastic, CdS/Glass, and ZnTe/GaAs Hetero-pairs Formed with Pulsed-laser Deposition." Bowling Green State University / OhioLINK, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1245089031.
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