Sham, Chun Hong = 金屬光栅光學特性的實驗和理論研究 / 沈鎮康. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2009. / Includes bibliographical references (leaves 109-111). / Abstract also in Chinese. / Sham, Chun Hong = Jin shu guang shan guang xue te xing de shi yan he li lun yan jiu / Shen Zhenkang. / Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Background --- p.1 / Chapter 1.2 --- Overview of the Thesis --- p.2 / Chapter 2 --- Basic Theory --- p.4 / Chapter 2.1 --- Dielectric Constant of Metals --- p.5 / Chapter 2.2 --- The Maxwell´ةs Equations --- p.7 / Chapter 2.3 --- Scaling Properties of the Maxwell´ةs Equations --- p.9 / Chapter 2.4 --- Translational Symmetry and the Bloch´ةs Theorem --- p.10 / Chapter 2.4.1 --- Continuous Translational Symmetry --- p.11 / Chapter 2.4.2 --- Discrete Translational Symmetry --- p.12 / Chapter 2.4.3 --- Photonic Bloch´ةs Theorem --- p.13 / Chapter 3 --- Principles of Rigorous Coupled Wave Analysis --- p.14 / Chapter 3.1 --- Mathematical Formulation --- p.15 / Chapter 3.2 --- One-layer systems --- p.15 / Chapter 3.3 --- Layered Systems --- p.19 / Chapter 3.3.1 --- Matching Boundary Conditions --- p.19 / Chapter 3.3.2 --- The Transfer Matrices --- p.21 / Chapter 3.3.3 --- Scattering Matrices --- p.22 / Chapter 3.4 --- Calculation of Reflection and Transmission --- p.24 / Chapter 3.5 --- Calculation of Field Pattern --- p.26 / Chapter 3.5.1 --- Finding the Coefficients --- p.26 / Chapter 3.5.2 --- Summing to Get the Field --- p.27 / Chapter 3.6 --- 5-polarization --- p.27 / Chapter 3.7 --- Analogy to mechanics --- p.29 / Chapter 3.8 --- Conclusion --- p.30 / Chapter 4 --- Numerical Implementation of Rigorous Coupled Wave Analysis --- p.31 / Chapter 4.1 --- Finite Number of Terms --- p.31 / Chapter 4.2 --- Fourier Factorization Rule --- p.32 / Chapter 4.3 --- Calculation of Field Pattern --- p.34 / Chapter 4.4 --- Transfer Matrix for Forward Deduction --- p.36 / Chapter 4.5 --- Calculation of Time-Averaged Poynting Vector --- p.36 / Chapter 4.6 --- Convergence of RCWA --- p.37 / Chapter 4.7 --- Simple Examples --- p.40 / Chapter 4.7.1 --- Oblique Incidence on Vacuum --- p.40 / Chapter 4.7.2 --- Oblique Incidence on Semi-Infinite Glass --- p.41 / Chapter 4.7.3 --- Normal Incidence on a Thin Gold Film --- p.41 / Chapter 5 --- A Tunable All-Direction Light Absorber --- p.43 / Chapter 5.1 --- Description of the Absorber --- p.44 / Chapter 5.2 --- Tunability --- p.45 / Chapter 5.3 --- Theoretical Understanding on the Results --- p.46 / Chapter 5.4 --- Other EM modes Involved --- p.49 / Chapter 5.5 --- Structural Flexibility --- p.54 / Chapter 6 --- Sample Preparation Techniques --- p.57 / Chapter 6.1 --- Interference Lithography --- p.57 / Chapter 6.1.1 --- Basic Principle of IL --- p.58 / Chapter 6.1.2 --- Experimental Setup for IL --- p.59 / Chapter 6.1.3 --- Experimental Procedures for IL --- p.60 / Chapter 6.1.4 --- Tuning the Period --- p.61 / Chapter 6.1.5 --- Tuning Grating Width --- p.62 / Chapter 6.1.6 --- Tuning the grating height --- p.64 / Chapter 6.2 --- Sputtering --- p.65 / Chapter 6.2.1 --- Description of Sputtering System --- p.65 / Chapter 6.2.2 --- Effect of Varying the Position on Sample Holder --- p.66 / Chapter 6.3 --- Chemical deposition of silver --- p.69 / Chapter 7 --- Sample Characterization Techniques --- p.72 / Chapter 7.1 --- Scanning Electron Microscope --- p.72 / Chapter 7.1.1 --- Grating width measurement --- p.72 / Chapter 7.1.2 --- Sidewall Coverage Measurement --- p.73 / Chapter 7.2 --- Thickness Measurement --- p.74 / Chapter 7.3 --- Reflectance Measurement --- p.75 / Chapter 7.3.1 --- Experimental Setup --- p.76 / Chapter 7.3.2 --- Use of Prism --- p.79 / Chapter 8 --- Experimental Realization of All-Direction Light Absorber --- p.82 / Chapter 8.1 --- Reflectance of Glass Substrate --- p.82 / Chapter 8.2 --- Planar Metal-SU8-Metal Systems --- p.87 / Chapter 8.3 --- SU8 Grating on Glass Substrate --- p.89 / Chapter 8.4 --- SU8 Grating on Gold Substrate --- p.92 / Chapter 8.4.1 --- Grating on a Thick Layer of Gold --- p.93 / Chapter 8.4.2 --- Grating on a Thin Layer of Gold --- p.93 / Chapter 8.5 --- Cavities-Embedded Systems and Future Work --- p.96 / Chapter 8.6 --- Summary and Future Experimental Work --- p.100 / Chapter 9 --- Conclusion --- p.102 / Chapter A --- Notes on Glass Cleaning --- p.104 / Chapter B --- An Experiment on Sidewall Coverage --- p.107 / Bibliography --- p.109

Estudamos a espectroscopia de correlação de intensidade de dois feixes laser com excesso de ruído de fase em condição de transparência eletromagneticamente induzida (EIT) em átomos frios de rubídio. Em particular, analisamos três aspectos da espectroscopia de corre-lação. O primeiro, no âmbito teórico, corresponde ao tratamento perturbativo da dinâmica atômica para o cálculo do espectro de correlação. Mostramos que, para campos com baixo ruído de fase, o termo a primeira ordem da expansão é suficiente para descrever completamente a correlação do sistema. No entanto, para campos que apresentam excesso de ruído de fase, observamos que é necessário considerar os termos de ordem superior para obtermos uma descrição completa do sistema. A abordagem perturbativa nos permite ter uma expressão analítica que relaciona o espectro de correlação no domínio das frequências com as propriedades de absorção e dispersão associadas ao meio atômico.\\\\ No âmbito experimental, analisamos duas situações diferentes para a espectroscopia de correlação. A primeira foi a espectroscopia de correlação para diferentes valores de dessintonia de frequência com relação à ressonância atômica. Mostramos pela primeira vez que a correlação apresenta ressonâncias na frequência das bandas laterais enquanto os campos estiverem dessintonizados fora da largura espectral dada pela emissão espontânea. Nossos resultados experimentais são descritos de maneira satisfatória pelo modelo perturbativo para a correlação definida no domínio da frequência. Além disso, mostramos que em certas condições, o modelo perturbativo se reduz ao nosso modelo heurístico para a função de correlação $g^2(0)$ no domínio do tempo, sendo ela uma aproximação válida para descrever correlação entre os campos.\\\\ O terceiro aspecto estudado neste trabalho se refere aos efeitos dinâmicos sobre a espectroscopia de correlação. Investigamos como a evolução transiente do sistema atômico, devido às forças de espalhamento que a luz exerce sobre os átomos, induz a uma assimetria espectral na correlação, se apresentando assim, como um efeito de ``histerese\". No entanto, para campos dentro da janela de transparência, mostramos que o sistema é insensível ao efeito de tais forças. Esta é a primeira observação do efeito dinâmico sobre a espectroscopia de correlação. Assim, mostramos que a espectroscopia de correlação se torna um ferramenta de alta precisão para detectar efeitos dinâmicos nos átomos frios, pois tais efeitos escapam da simples observação quando é feita a espectroscopia de transmissão padrão. / We studied the intensity correlation spectroscopy of two lasers beams with excess of phase noise in electromagnetically induced transparency (EIT) condition in cold rubidium atoms. In particular, we analyzed three aspects of correlation spectroscopy. In the first one, as a theoretical approach, I proposed a perturbative treatment for the atomic dynamics in order to calculate the correlation spectrum. We show that for electromagnetic fields with low phase noise, the first order term of the expanssion is sufficient for a complete description of the system. However, when the fields present excess of phase noise, it is shown that higher order terms are necessary to describe the system completely. The perturbative approach allows the contruction of an analytical expression which maps the correlation spectrum in the frequency domain, with the absorptive and dispersive properties of the atomic medium.\\\\ In the experimental part, we analyze two different situations for the correlation spectroscopy. In the first one, was the correlation spectroscopy for different values of frequency detuning with respect to the atomic resonance. We show for the first time that the correlation has resonances at the exactly sideband\'s frequencies, if the light fields optical frequencies are detuned from the natural spectral width given by the spontaneous emission. Our experimental results are described satisfactorily by the perturbative model for the correlation set in the frequency domain. Furthermore, we show that under certain conditions, the perturbative contains our heuristic model for the correlation function $g^2(0)$ in the time domain, and it is a valid approximation to describe correlation between fields.\\\\ The third aspect studied in this work refers to the dynamical effects on the correlation spectroscopy. We investigate the transient evolution of the atomic system due to the scattering forces that light exerts on the atoms, inducing a spectral asymmetry in the correlation, appearing as an \'\'hysteresis effect\". However, for fields within the transparency window, we show that the system is insensitive to the effect of such forces. This is the first observation of the dynamical effect in the correlation spectroscopy. Thus, we show that correlation spectroscopy becomes a high-precision tool to detect dynamical effects in cold atoms, because such effects escape from the simple observation in the standard transmission spectroscopy.

Karenia brevis, a toxic dinoflagellate species that blooms regularly in the Gulf of Mexico, frequently causes widespread ecological and economic damage and can pose a serious threat to human health. Satellite-based ocean color imagery may provide a means for detecting and monitoring blooms, providing early alerts to coastal communities. However, a technique for discriminating K. brevis from other chlorophyll-containing algae is required. Between 1999 and 2001, a large bio-optical data set consisting of spectral measurements of remote-sensing reflectance (Rrs(lambda)), absorption (a(lambda)), and backscattering (bb(lambda)) along with chlorophyll a concentrations was collected on the central west Florida shelf (WFS) as part of the Ecology and Oceanography of Harmful Algal Blooms (ECOHAB) and Hyperspectral Coastal Ocean Dynamics Experiment (HyCODE) programs. Reflectance model simulations indicate that cellular pigmentation is not responsible for the factor of 3 to 4 decrease in Rrs(lambda) observed in waters containing greater than 104 cells 1-1 of K. brevis. Instead, particulate backscattering coefficients measured inside K. brevis blooms are responsible for this decreased reflectivity as they were significantly lower than values measured in high-chlorophyll (>1 mg m-3), diatom-dominated waters containing fewer than 104 cells 1-1 of K. brevis. A paucity of high-backscattering detritus present in K. brevis blooms caused by decreased grazing pressure perhaps due to cellular toxicity along with a general inability of K. brevis to out compete diatoms and bloom in high-nutrient, high-backscattering estuarine waters may explain this low backscattering. A classification technique for detecting high-chlorophyll, low-backscattering K. brevis blooms is developed. In addition, a method for quantifying chlorophyll concentrations in positively flagged pixels using fluorescence line height (FLH) data obtained from the Moderate Resolution Imaging Spectroradiometer (MODIS) is introduced. Both techniques are successfully applied to Sea-viewing Wide Field-of-view Sensor (SeaWiFS) and MODIS data acquired in late August 2001 and validated using in situ K. brevis cell concentrations.

Thesis (Ph. D.)--West Virginia University, 2004. / Title from document title page. Document formatted into pages; contains xiii, 150 p. : ill. Includes abstract. Includes bibliographical references (p. 141-150).

Thesis (Ph. D.)--University of Washington, 1996. / Vita. Includes bibliographical references (p. [158]-162).

Estudamos a espectroscopia de correlação de intensidade de dois feixes laser com excesso de ruído de fase em condição de transparência eletromagneticamente induzida (EIT) em átomos frios de rubídio. Em particular, analisamos três aspectos da espectroscopia de corre-lação. O primeiro, no âmbito teórico, corresponde ao tratamento perturbativo da dinâmica atômica para o cálculo do espectro de correlação. Mostramos que, para campos com baixo ruído de fase, o termo a primeira ordem da expansão é suficiente para descrever completamente a correlação do sistema. No entanto, para campos que apresentam excesso de ruído de fase, observamos que é necessário considerar os termos de ordem superior para obtermos uma descrição completa do sistema. A abordagem perturbativa nos permite ter uma expressão analítica que relaciona o espectro de correlação no domínio das frequências com as propriedades de absorção e dispersão associadas ao meio atômico.\\\\ No âmbito experimental, analisamos duas situações diferentes para a espectroscopia de correlação. A primeira foi a espectroscopia de correlação para diferentes valores de dessintonia de frequência com relação à ressonância atômica. Mostramos pela primeira vez que a correlação apresenta ressonâncias na frequência das bandas laterais enquanto os campos estiverem dessintonizados fora da largura espectral dada pela emissão espontânea. Nossos resultados experimentais são descritos de maneira satisfatória pelo modelo perturbativo para a correlação definida no domínio da frequência. Além disso, mostramos que em certas condições, o modelo perturbativo se reduz ao nosso modelo heurístico para a função de correlação $g^2(0)$ no domínio do tempo, sendo ela uma aproximação válida para descrever correlação entre os campos.\\\\ O terceiro aspecto estudado neste trabalho se refere aos efeitos dinâmicos sobre a espectroscopia de correlação. Investigamos como a evolução transiente do sistema atômico, devido às forças de espalhamento que a luz exerce sobre os átomos, induz a uma assimetria espectral na correlação, se apresentando assim, como um efeito de ``histerese\". No entanto, para campos dentro da janela de transparência, mostramos que o sistema é insensível ao efeito de tais forças. Esta é a primeira observação do efeito dinâmico sobre a espectroscopia de correlação. Assim, mostramos que a espectroscopia de correlação se torna um ferramenta de alta precisão para detectar efeitos dinâmicos nos átomos frios, pois tais efeitos escapam da simples observação quando é feita a espectroscopia de transmissão padrão. / We studied the intensity correlation spectroscopy of two lasers beams with excess of phase noise in electromagnetically induced transparency (EIT) condition in cold rubidium atoms. In particular, we analyzed three aspects of correlation spectroscopy. In the first one, as a theoretical approach, I proposed a perturbative treatment for the atomic dynamics in order to calculate the correlation spectrum. We show that for electromagnetic fields with low phase noise, the first order term of the expanssion is sufficient for a complete description of the system. However, when the fields present excess of phase noise, it is shown that higher order terms are necessary to describe the system completely. The perturbative approach allows the contruction of an analytical expression which maps the correlation spectrum in the frequency domain, with the absorptive and dispersive properties of the atomic medium.\\\\ In the experimental part, we analyze two different situations for the correlation spectroscopy. In the first one, was the correlation spectroscopy for different values of frequency detuning with respect to the atomic resonance. We show for the first time that the correlation has resonances at the exactly sideband\'s frequencies, if the light fields optical frequencies are detuned from the natural spectral width given by the spontaneous emission. Our experimental results are described satisfactorily by the perturbative model for the correlation set in the frequency domain. Furthermore, we show that under certain conditions, the perturbative contains our heuristic model for the correlation function $g^2(0)$ in the time domain, and it is a valid approximation to describe correlation between fields.\\\\ The third aspect studied in this work refers to the dynamical effects on the correlation spectroscopy. We investigate the transient evolution of the atomic system due to the scattering forces that light exerts on the atoms, inducing a spectral asymmetry in the correlation, appearing as an \'\'hysteresis effect\". However, for fields within the transparency window, we show that the system is insensitive to the effect of such forces. This is the first observation of the dynamical effect in the correlation spectroscopy. Thus, we show that correlation spectroscopy becomes a high-precision tool to detect dynamical effects in cold atoms, because such effects escape from the simple observation in the standard transmission spectroscopy.

[EN] The development and optimization of new combustion modes is nowadays an important research field, to reduce the pollutant emissions of the reciprocating internal combustion engines. Their development requires the use of a wide variety of experimental and theoretical tools, which make it possible to know and understand their fundamentals. In this context the main objective of this Thesis is framed: the development and optimization of measuring and visualization techniques, to reach the level of accuracy and detail required for current and future studies of that kind. The work has been based on the characterization of the diesel diffusion combustion to be able to focus the study on the methodological part, thanks to the extensive knowledge available on this combustion mode. The work has been divided in two main blocks. The first one is focused on the characterization of evaporation and air-fuel mixture formation processes. For this purpose, a new technique has been developed and applied, based on the light absorption by the fuel molecules (UV-VIS LAS), which allows measuring the vapour fuel local concentration within a diesel spray. It has been optimized to be applied under operating conditions similar to those found in a compression ignition engine with fuels whose optical properties are not optimal, but which are interesting for research due to its simplicity. Moreover, a new methodology has been developed for measuring the absorption coefficient of the fuels, under similar operating conditions (i.e. pressure and temperature) than those found within the combustion chamber of a compression ignition engine. Results have been analysed in detail, to be able to define the limitations and reliability of the methodology proposed. The second block corresponds to the characterization of the combustion process and the soot formation. For this purpose, a complex optical set-up has been developed which made it possible to simultaneously apply the three most used techniques that can be found in literature for soot measuring within a diesel flame: Laser Extinction Method, 2-Colour Pyrometry and Laser-Induced Incandescence. Results obtained by means of the three techniques have been compared in detail, not only to identify the main advantages and drawbacks of each technique, but also their reliability under different operating conditions. / [ES] El desarrollo y optimización de nuevos modos de combustión constituye actualmente un campo importante de investigación, para reducir la emisión de contaminantes en motores de combustión interna alternativos. Su desarrollo requiere del uso de gran variedad de herramientas experimentales y teóricas, que permitan conocer y comprender sus fundamentos. En este contexto se enmarca el objetivo principal de esta Tesis: la mejora y el desarrollo de técnicas de visualización y medida, para alcanzar el nivel de detalle y la precisión requeridos para estudios actuales y futuros de esta índole. El trabajo se ha basado en la caracterización de la combustión diésel por difusión para poder centrar el estudio en la parte metodológica, gracias al amplio conocimiento disponible sobre este modo de combustión. El trabajo se ha dividido en dos apartados principales. El primero de ellos se centra en la caracterización de los procesos de evaporación y formación de la mezcla aire-combustible. Para ello, se he desarrollado y puesto en práctica una técnica basada en la absorción de luz por parte de las moléculas de combustible (UV-VIS LAS), que permite medir la concentración local de combustible evaporado en el seno de un chorro diésel. Esta ha sido optimizada para ser aplicada en condiciones de operación semejantes a las de un motor de encendido por compresión con combustibles cuyas propiedades ópticas no son óptimas, pero que son de gran interés para investigación dada su simplicidad. Además, se ha desarrollado una metodología para la medida del coeficiente de absorción de los combustibles, bajo las mismas condiciones de operación (presión y temperatura) que las que se dan en la cámara de combustión de un motor de encendido por compresión. Los resultados obtenidos se han analizado con detalle, para poder definir los límites y la fiabilidad de la metodología propuesta. El segundo apartado corresponde a la caracterización del proceso de combustión y la formación de hollín. Para ello, se ha desarrollado un montaje óptico complejo que ha permitido aplicar de forma simultánea las tres técnicas más utilizadas en la literatura para la medida del hollín en una llama diésel: Método de Extinción Láser, Pirometría 2-Colores e Incandescencia Inducida por Láser. Los resultados obtenidos mediante las tres técnicas han sido comparados detalladamente, no sólo para identificar las principales ventajas e inconvenientes de cada técnica, sino también la fiabilidad de las mismas para distintas condiciones de operación. / [CAT] El desenvolupament y optimització de nous modes de combustió constitueixen actualment un camp important d'investigació, para reduir la emissió de contaminants en motors de combustió internat alternatius. El seu desenvolupament requereix del us de gran varietat de ferramentes experimentals i teòriques, que permeten conèixer i comprendre els seus fonaments. En este context s'emmarca l'objectiu principal d'esta tesi: la millora i el desenvolupament de tècniques de visualització i mesura, per a conseguir el nivell de detall i la precisió requerits per a estudis actuals i futurs d'esta índole. El treball s'ha basat en la caracterització de la combustió dièsel per difusió per a poder centrar l'estudi en la part metodològica, gràcies a l'ampli coneixement disponible sobre este mode de combustió. El treball s'ha dividit en dos apartats principals. El primer d'ells se centra en la caracterització dels processos d'evaporació i formació de la mescla aire-combustible. Per això, s'ha desenvolupat i posat en pràctica una tècnica basada en la absorció de llum per part de les molècules de combustible (UV-VIS LAS), que permet mesurar la concentració local de combustible evaporat en el si d'un esprai dièsel. Esta ha sigut optimitzada per a ser aplicada en condicions d'operació semblants a les d'un motor d'encesa per compressió i combustibles amb propietats òptiques que no son les òptimes, però els quals són de gran interés en investigació donada la seua simplicitat. A més, s'ha desenvolupat una metodologia per a la mesura del coeficient d'absorció dels combustibles, a les mateixes condicions d'operació (pressió i temperatura) que les que es donen en la cambra de combustió d'un motor d'encesa per compressió. Els resultats obtinguts s'han analitzat amb detall, per a poder definir els límits i la fiabilitat de la metodologia proposada. El segon apartat correspon a la caracterització del procés de combustió i la formació de sutja. Per a això, s'ha desenvolupat un muntatge òptic complex que permés aplicar de forma simultània les tres tècniques més utilitzades en la literatura per a la mesura de la sutja en una flama dièsel: Mètode d'Extinció Làser, Pirometria 2-Colors i Incandescència Induïda per Làser. Els resultats obtinguts per mitjà de les tres tècniques han sigut comparats detalladament, no sols per a identificar els principals avantatges i inconvenients de cada tècnica, sinó també la fiabilitat d'aquestes per a distintes condicions d'operació. / Micó Reche, C. (2015). DEVELOPMENT OF MEASUREMENT AND VISUALIZATION TECHNIQUES FOR CHARACTERIZATION OF MIXING AND COMBUSTION PROCESSES WITH SURROGATE FUELS [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/58991 / TESIS

Nonlinear organic liquids that exhibit two-photon absorption (TPA) function as good optical limiters for sensor protection from laser pulses. L34 (4-butyl-4'-propyl-diphenylethyne) is a liquid organic compound exhibiting nonlinear optical absorption. A thiol- derivatized analog of L34 (“thiol-L34”) was prepared to bind the molecules to the surface of gold nanoparticles. Surface binding is necessary to investigate synergy between nonlinear optical absorption of gold nanoparticles and thiol-L34. Thiol-L34 was prepared in a six-step organic synthesis starting from 3-(4-bromophenyl) propionic acid. Au nanoparticles with <15 nm diameter have been prepared and sensitized with the thiol-L34 compound for assessment of their nonlinear optical behavior. Diazolylmethenes a class of metal-coordinating dyes that are similar to dipyrrins with some substitutions of nitrogen atoms in place of carbon atoms. Modification in the framework of dipyrrinoid dyes via this replacement of nitrogen for carbon atoms may lead to compounds that serve as effective agents for bioimaging and/or photodynamic therapy. Several routes to the synthesis of di-(1,2,3)-triazolylmethenes, di-(1,2,4)-triazolylmethenes, and ditetrazolylmethenes are presented.

Effective light energy conversion into other forms of energy in metal and metal compound nanoparticles has been of great interest in past decades. Being illuminated by incident light, electrons in the nanoparticles can be excited to higher energy states followed by deposition of energy into other molecules around their surface and the lattices in the following relaxation process. Ultrafine nanoparticles are thus preferred in these processes due to their high specific surface areas. Moreover, the portion of excited electrons with higher energies is higher in smaller nanoparticles than in larger ones. However, the overall light power absorbed by nanoparticles is proportional to the square of particle size, which causes the ultrafine nanoparticles not to efficiently absorb the incident light, or to drive further chemical or physical processes.Light antennae materials are usually employed to enhance the light absorption of these ultrafine nanoparticles. Plasmonic nanoparticles, e.g., Ag, Au, Cu, and Al nanoparticles, enhance the light absorption of loaded nanoparticles mainly through strong electromagnetic fields generated near their surfaces and have been proven to be effective light antennae to benefit the light energy conversion of ultrafine nanoparticles. On the other hand, spherical dielectric particles, e.g., silicon dioxide nanospheres, represent a different type of light antennae with the advantages of low cost, simple synthesis, and negligible Ohmic loss when being illuminated. When the sizes of high geometric symmetry dielectric nanospheres are comparable with the wavelength of the incident light, Mie scattering can happen based on the difference in refractive index between the sphere and the surrounding medium, generating size-dependent scattering resonances at various wavelengths. At these wavelengths, strong electric fields can be created on the surface of dielectric spheres to enhance the light absorption of the nanoparticles loaded on the surface. Previous works have shown that silica nanospheres with a diameter of several hundreds of nanometers can effectively enhance the light absorption of ultrafine Pt nanoparticles and benefit photocatalytic reactions, e.g., selective oxidation of benzyl alcohol. Over the past few years, this concept has been broadened to other ultrafine nanoparticles to study their novel photo-to-chemical/physical properties. However, the availability and comprehensive understanding of the optical properties of this class of composite particles still need to be improved. These challenges limit the further development of these composite materials in new light energy conversion processes. This dissertation aims at studying this class of novel ultrafine nanoparticles/dielectric sphere composite particles synthesis and optical properties. In Chapter 2, a synthesis protocol of ultrafine ruthenium oxyhydroxide nanoparticles on the surface of silica nanospheres’ surfaces is introduced. Unlike the traditional synthesis of nanoparticles in solution followed by a loading process, the method developed in this chapter only requires the injection of aqueous ruthenium salt solution into a silica nanosphere dispersion. The obtained ultrafine nanoparticles with sizes of 2-3 nm are characterized to be ruthenium oxyhydroxide (RuOOH) nanoparticles. The silica nanospheres are crucial in stabilizing these ultrafine RuOOH nanoparticles and enhancing their light absorption. Due to the presence of ruthenium-oxygen bonds in the nanoparticles, the absorbed photons are converted to heat and transferred to the surrounding media with a photo-to-thermal conversion efficiency close to the unity. Experimental results have shown that heat can be effectively used in accelerating the reaction rate of selective oxidation of benzyl alcohol by molecular oxygen. Kinetics data also have shown that these ultrafine RuOOH nanoparticles are able to activate molecular oxygen adsorbed on their surfaces, which represents a novel property of these ultrafine RuOOH nanoparticles that is not observed in other traditional ruthenium catalysts. In Chapter 3, a more general synthesis method of ultrafine metal and metal oxyhydroxide nanoparticles on silica nanospheres is developed, inspired by the synthetic route in Chapter 2. Instead of functionalizing silica surfaces with silane agents with amino groups, the silica surfaces are selectively etched by an aqueous base to create a high density of surface hydroxyl groups. These hydroxyl groups can provide basic sites to stabilize metal ions in aqueous dispersion, which are nuclei for the further growth of larger metal oxyhydroxide nanoparticles. In this chapter, more than ten kinds of metal ions are loaded onto silica spheres, forming oxyhydroxide nanoparticles with average sizes below 5 nm. Some oxyhydroxide nanoparticles can be reduced by 5% H2/N2 to form metal nanoparticles with their ultrafine sizes maintained. The synthesis protocol is promising in preparation of bimetallic samples. The composition and optical absorption of all obtained composite particles are analyzed, demonstrating the practicability of utilizing the reported method to prepare high-quality light-absorbing composite particles. In Chapter 4, the optical absorption property of the composite particle is systematically studied. Using ultrafine Pt nanoparticles as the light absorbing material, the light absorptions of composite particles consisting of silica spheres with diameters from 100 to 1100 nm loaded with these Pt nanoparticles are studied. Through the combination of theoretical calculation based on Mie theory and the measured optical absorption spectra, the scattering resonance peaks are successfully located in each sample. It is also found that the photonic crystal effect and the general absorption of Pt nanoparticles can contribute to the light absorption spectra, especially at higher wavelengths. The relationship between the general absorption of Pt nanoparticles and the packing density of the powder is further studied. The successful deconvolution of several components in the absorption spectra can guide the further rational design of composite particles in optical-related applications. In Chapter 5, the composite particle system is further broadened to using high refractive index zinc sulfide nanospheres as a light antenna. The use of a higher refractive index light antenna is promising for obtaining higher light absorption enhancement in loaded ultrafine nanoparticles, even though the sample is dispersed in organic media with a high refractive index as well. After the successful loading of Pt nanoparticles to the surface of silica-coated zinc sulfide nanospheres, a protocol for analyzing their light absorption spectra in organic media is proposed. Size-dependent scattering resonance peaks are observed in bare zinc sulfide nanospheres and can be utilized to enhance the light absorption of Pt nanoparticles, even when the sample is sealed in high refractive index polymeric matrices. The composite particles are further employed in photothermal tests, the results prove that the better light absorption enhancement using zinc sulfide than silica nanospheres. The results introduced in this dissertation represent the first systematic and comprehensive study of ultrafine metal and metal oxyhydroxide nanoparticles loaded on the surface of dielectric light antenna particles. The conclusions open an avenue to further rational design of high-performance light-absorbing composite particles to be used in photo-to-thermal/chemical processes. / Chemistry

Granada é um grupo de seis silicatos com a mesma estrutura cristalina e fórmulas químicas semelhantes, diferindo um do outro pelos cátions, dos quais o GROSSULAR de fórmula química Ca IND.3Al IND.2Si IND.30 IND.12 é o segundo mineral mais abundante no Brasil, e talvez o mais colorido das granadas. Foram obtidas duas amostras de Araçuaí - Minas Gerais, denominadas GV e GVI que diferem somente no teor de impurezas, as quais foram pulverizadas e peneiradas para realizar medidas de Termoluminescência (TL) e Ressonância Paramagnética Eletrônica (EPR); e cortadas em lâminas e polidas para as medidas de Absorção Ótica(AO). A análise de fluorescência mostrou a presença de 1,37mol% de Fe IND.20 IND.3 na amostra GV e, 6,2mol% na GVI, 1,03mol% de MnO na GV e 0,26mol% na GVI, 0,66mol% de MgO na GV e 0,72mol% na GVI, que participam como defeitos extrínsecos na amostra. A curva de emissão termoluminescente apresentou um pico intenso em alta temperatura em 470ºC para as amostras naturais. Amostras tratadas termicamente em 600ºC/1h. e irradiadas com diferentes doses gama mostraram picos em 145, 235 e 335ºC em GV e em 145, 200, 250, 335 e 445ºC em GVI, mostrando-se mediante a deconvolução da curva TL que GV está formada de seis picos e GVI de sete picos bastante superpostos. Enquanto que em GV os picos de baixa temperatura crescem mais rápido com a irradiação, é o pico em 340ºC que aumenta rapidamente em GVI mantendo sua individualidade, porém em ambos casos os picos TL crescem sublinearmente após 100Gy de doses gama. Outras diferenças consideráveis entre as amostras GV e GVI foram observadas do comportamento com os diferentes tratamentos térmicos, observando-se o aumento da sensibilidade TL somente em GV enquanto que na amostra GVI, não houve a sensibilização, mas, um comportamento bastante caótico. A irradiação ultra-violeta (UV) produz decaimento na intensidade TL, onde em GV a TL residual diminui com a temperatura do pico e em GVI o comportamento é contrário. Estas diferenças não podem ser explicadas baseados somente na diferença do teor de impurezas das amostras e, possivelmente a estrutura cristalina esteja também envolvida. Os íons de ferro e manganês entram na estrutura do grossular, e o cálculo do campo cristalino mostrou que o Fe POT.3+ pode ocupar o sítio tetraédrico e octaédrico substituindo o AI e Si. Os íons Mn POT.2+ e Fe POT.2+ ocupam posições dodecaédricas substituindo o Ca na estrutura. O espectro de EPR. apresentou sinais em g=4,3 , 6,0 relacionados ao ferro e, o sinal em g=2,004 devido à interação de troca e dipolar de ambos íons Fe POT.3+ e Mn POT.2+. O recozimento das amostras em alta temperatura mostrou que os íons de Fe POT.2+ oxidam-se para Fe POT.3+ e os íons de Mn POT.3+ mudam para Mn POT.2+, respectivamente. Não foi encontrada uma correlação entre os defeitos responsáveis pelos espectros de AO e EPR e os centros que participam na termoluminescência. / Garnet is a group of six silicates with the same crystal structure but with chemical formula differing by their cations. Grossular of chemical formula Ca3AlzSi3012 is the second most abundant garnet in Brazil and probably the most colorful of the garnets. Two samples of grossular, named GV and GVI were obtained of Araçuai-Minas Gerais difIering by impurities content. These samples were pulverized and sieved for termoluminescence (TL) and electron paramagnetic resonance (EPR) measurements. Polished plates of 2.0mm thickness were prepared for optical absorption (AO) measurements. The X-ray fluorescence has revealed several kinds of impurities, being the most important 1,37mol% of Fe203 in GV e, 6,2mol% in GVI, 1,03mol% of MnO in GV and O,26mol% in GVI, O,66mol% of MgO in GV and 0,72mol% in GVI, which might participate as extrinsic defects in the samples. The TL glow curve of natural samples shows a high temperature peak at 470°C that is greater in GVI than in GV. Samples heat treated at 600°C/1h and irradiated with different gamma dose present peaks at 145, 235 and 335°C in GV and, 145 200, 250, 335 and 445°C in GVI. However, the glow curve deconvolution shows that in fact GV is formed by six peaks and GVI by seven peaks overlapped. While, the low temperature peaks increase with the dose in GV, it is the last peak in GVI (340°C) that increases fast keeping its individuality, however a similar sublinear dependence with the irradiation dose was founded for both samples. Other differences between these samples refer to the behavior with the pre-irradiation anneal temperature, namely increase in the TL sensibilities observed only in GV and a caotic behavior in GVI. The UV irradiation produces decay in TL intensity with exposure time. The residual TL diminishes with the peak temperature in GV, being opposite in GVI. The iron and manganese ions can replace some ions in the grossular structure. The crystal field analysis shows that the Fe3+ ions occupy tetrahedral and octahedral sites replacing AI and Si, similarly Ca can be substituited by Fe2+ and Mn2+ in the dodecahedral position. The EPR spectra show signals in g=4.3, g=6.0 related to the iron and g=2.004 signal is due to the dipolar and exchange interactions between M 712+ and Fé+ ions. The high temperature heat treatment of the samples give rise to the change from Fe2+ to Fe3+ by oxidation and from Mn3+ to Mn2+ . No correlation between the defects responsible for the AO and EPR spectra and the TL centers was found.