Submitted by Renata Lopes (renatasil82@gmail.com) on 2017-06-07T19:30:35Z No. of bitstreams: 1 alisonarantesgoncalves.pdf: 3160281 bytes, checksum: b3f8a1585b5f5884a5571e6857646b8b (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2017-06-26T17:46:44Z (GMT) No. of bitstreams: 1 alisonarantesgoncalves.pdf: 3160281 bytes, checksum: b3f8a1585b5f5884a5571e6857646b8b (MD5) / Made available in DSpace on 2017-06-26T17:46:44Z (GMT). No. of bitstreams: 1 alisonarantesgoncalves.pdf: 3160281 bytes, checksum: b3f8a1585b5f5884a5571e6857646b8b (MD5) Previous issue date: 2012-03-08 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Apresentamos uma teoria para obtenção da seção de choque de espalhamento inelástico de luz, espalhamento Raman, a temperatura de T = OK em um gás de elétrons quasi-bidimensional formado pela heteroestrutura semicondutora de A1GaAs-GaAs dopada seletivamente. Os cálculos de estrutura eletrônica foram baseados na Teoria do Funcional Densidade dentro da aproximação de densidade local. Os cálculos para a seção de choque foram realizados em geometria de retroespalhamento e em regime de ressonância do laser incidente com o gap ótico de spin-órbita do GaAs. Estudamos os mecanismos de excitações de densidade de carga e excitações de densidade de spin. Os resultados obtidos foram [1]: 1) a observação do colapso do termo de Hartree nas excitações de densidade de carga para baixas densidades, observado experimentalmente por Ernst et al. [2]; 2) a observação de um cruzamento anômalo entre as excitações de densidade de carga e densidade de spin, em virtude dos funcionais de exchange-correlação. Este efeito constitui um teste de validade para as parametrizações adotadas; 3) a predição da existência de excitações de mais alta energia, ainda não observadas experimentalmente. Finalmente, demonstramos que o formalismo desenvolvido permite mapear as excitações eletrônicas na teoria BCS. / We present a theory for obtaining the inelastic light scattering cross section, Raman scattering, at T = OK temperature in a quasi-bidimensional electron gas formed by the GaAs-A1GaAs semiconductor heterostructure doped selectively. The electronic structure calculations were based on Density Functional Theory within the local density approximation. The calculations for the cross section were performed in backscattering geometry and resonant regime of the incident laser with the spin-orbit optical gap of GaAs . We study charge density excitations mechanism and spin density excitations mechanism. Our results were as follows [1] 1) the observation of the collapse of the Hartree term in the charge density excitation for low densities, observed experimentally by Ernst et al. [2], 2) the observation of an anomalous cross between charge density and spin density excitations, due to the exchange-correlation functional. This effect is a validity test for the adopted parameterizations; 3) the prediction of the existence of excitations of higher energy, not yet observed experimentally. Finally, we demonstrate that the formalism developed enables mapping the electronic excitations in the BCS theory, which describes the normal superconducting state.

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The financial requirements between fiber optic sensors and conventional sensors are gradually declining, which, despite many advatages and wide range of applicationas, has slowed down the demand for these sensors. With the demand for fiber optic sensors also grow the requirements for the parameters of these sensors. This thesis deals with distributed temperature fiber optic sensors. Non--linear phenomen in optical fibers, such as Raman scattering is used for measuring with these sensors. This scatterin was used to obtain information about temperature, which effected the optical cable under the test.

L-3,4-dihyroxyphenylalanine (L-DOPA, levodopa) is a gold standard treatment of Parkinson's disease. Lately, it has been found that some of its deuterated analogues exhibit higher potency in the treatment; thus, they could replace L-DOPA. The subject of this thesis was a study of L-DOPA and its deuterated derivatives by the means of vibrational spectroscopy (Raman, ROA, IR, and VCD) and a comparison of the experimental results to a quantum mechanical simulations of the spectra. ROA and VCD are chiroptical methods, thus they are suitable for measurement of chiral molecules amongst which L-DOPA indeed belongs. Thanks to the quantum chemistry calculations, which yielded spectra with a very good agreement with the experiment, we were able to assign experimental spectral features to individual vibrational modes of the L-DOPA. The use of chiroptical techniques (mainly ROA) enabled an assignment of an absolute configuration of double deuterated derivative of L-DOPA, α,β-D2-L-DOPA. It reviled that it occurs in a (S-α,S-β)-enantiomeric form.

Plasmonic nanocrystals have a unique ability to support localized surface plasmon resonances and exhibit rich and intriguing optical properties. Engineering plasmonic nanocrystals can maximize their potentials for specific applications. In this dissertation, we developed three unprecedented Au nanorod-based plasmonic nanocrystals through rational design of the crystal shape and/or composition, and successfully demonstrated their applications in light condensation, photothermal conversion, and surface-enhanced Raman spectroscopy (SERS). The “Au nanorod-Au nanosphere dimer” nanocrystal was synthesized via the ligand-induced asymmetric growth of a Au nanosphere on a Au nanorod. This dimeric nanostructure features an extraordinary broadband optical absorption in the range of 400‒1400nm, and it proved to be an ideal black-body material for light condensation and an efficient solar-light harvester for photothermal conversion. The “Au nanorod (core) @ AuAg alloy (shell)” nanocrystal was built through the epitaxial growth of homogeneously alloyed AuAg shells on Au nanorods by precisely controlled synthesis. The resulting core-shell structured, bimetallic nanorods integrate the merits of the AuAg alloy with the advantages of anisotropic nanorods, exhibiting strong, stable and tunable surface plasmon resonances that are essential for SERS applications in a corrosive environment. The “high-index faceted Au nanorod (core) @ AuPd alloy (shell)” nanocrystal was produced via site-specific epitaxial growth of AuPd alloyed horns at the ends of Au nanorods. The AuPd alloyed horns are bound with high-index side facets, while the Au nanorod concentrates an intensive electric field at each end. This unique configuration unites highly active catalytic sites with strong SERS sites into a single entity and was demonstrated to be ideal for in situ monitoring of Pd-catalyzed reactions by SERS. The synthetic strategies developed here are promising towards the fabrication of novel plasmonic nanocrystals with fascinating properties for nanoplasmonics and nanophotonics.

Amorphous and nano- or micro- crystalline silicon thin films are intensively studied materials for photovoltaic applications. The films are used as intrinsic layer (absorber) in p-i-n solar cells. As opposed to crystalline silicon solar cells, the thin films contain about hundred times less silicon and can be deposited at much lower temperatures (typically around 200 0 C) which saves energy needed for production and makes it possible to use various low cost (even flexible) substrates. However, these films have a complex microstructure, which makes it difficult to measure and describe the electronic transport of the photogenerated carriers. Yet, the understanding of the structure and electronic properties of the material at nanoscale is essential on the way to improve the efficiency solar cells. One of the main aims of this work is the study of the structure and mechanical properties of the mixed phase silicon thin films of various thicknesses and structures. The key parameter of microcrystalline silicon is the crystallinity, i.e., the microcrys- talline volume fraction. It determines internal structure of the films which, in turn, decides about many other properties, including charge transport and mechanical sta- bility. Raman microspectroscopy is a fast and non-destructive method for probing the...

京都大学 / 0048 / 新制・課程博士 / 博士(エネルギー科学) / 甲第18611号 / エネ博第307号 / 新制||エネ||63(附属図書館) / 31511 / 京都大学大学院エネルギー科学研究科エネルギー応用科学専攻 / (主査)教授 大垣 英明, 教授 白井 康之, 教授 松田 一成 / 学位規則第4条第1項該当 / Doctor of Energy Science / Kyoto University / DFAM

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Volumetric optical microscopy has the advantages of quantitative and global measurement of three-dimensional (3D) biological specimens with high spatial resolution and minimum invasion. However, current volumetric imaging technologies based on light transmission, scattering or fluorescence cannot reveal specimen’s chemical distribution that brings insights to study the chemical events in organisms and their metabolism, functionality, and development. Stimulated Raman scattering (SRS) microscopy allowing visualization of chemical contents based on their intrinsic molecular vibrations is an emerging imaging technology to provide rapid label-free volumetric chemical imaging. This dissertation describes three methodologies for developing advanced volumetric SRS imaging technologies to address the challenges of imaging in vivo samples, imaging speed, and axial resolution. In the first methodology, SRS volumetric imaging is enabled by axially scanning the laser foci for sectioning different depth layers. In Chapter 2, we utilize a piezo objective positioner to drive the objective. Combining with the tissue clearance technique, we realize volumetric SRS imaging up to 500 µm depth in brain tissues showing the potential for 3D staining-free histology. The limitations of piezo scanning are slow speed and disturbance to in vivo samples while rapidly scanning the objective. To tackle the limitations, in Chapter 3, we develop a remote-focusing volumetric SRS microscope based on a deformable mirror and adaptive optics optimization, allowing focal scanning without physically moving the objective or sample. We demonstrate in vivo monitoring of chemical penetration in human sweat pores. In the second methodology, instead of axially scanning the laser foci, the SRS volumetric imaging is enabled by projection imaging with extended depth-of-focus (DOF) beams such as Bessel beams and low numerical-aperture beams. The extended DOF beams integrate SRS signals along the propagation direction to form projection images; thus, a single lateral scan obtains the volumetric chemical information, significantly increasing the volumetric imaging speed for measuring chemical content over a large volume. In Chapter 4, we describe a stimulated Raman projection microscope for fast quantitation of chemicals in a 3D volume. However, projection imaging intrinsically loses axial resolution. We addressed the limitation by developing SRS projection tomography. Mimicking computed tomography, the axial information is reconstructed by angle-dependent projection images obtained by sequentially rotating the sample in a capillary glass tube within the SRS focus. Nevertheless, sample rotation is complicated and not compatible with in vivo samples. To address the difficulty, in Chapter 5, we develop tilted-angle-illuminated stimulated Raman projection tomography which utilizes tilted-angle beams with a tilted angle respected to the optical axis of the objective to obtain angle-dependent projections. This scheme is free of sample rotation and enables fast projection scanning for pushing the imaging speed. The calibration approach and vector-field back-projection algorithm are developed for the multi-view tomographic reconstruction. In the third methodology, we improve the spatial resolution in miniature volumetric SRS imaging via the innovation of metasurface photonics. In developing an SRS endoscope for volumetric chemical imaging inside the human body, the axial resolution deteriorates due to chromatic and monochromatic aberrations induced by poorly made miniature objective lenses. In Chapter 6, we develop a silicon metasurface tailored for compensating the phase errors between the pump and Stokes wavelengths of a singlet refractive lens. Integrating the metasurface with the refractive lens, the hybrid achromatic metalens is compact and provides nearly diffraction-limit resolution, demonstrating a way for developing high resolution chemical imaging endoscopy.

This thesis is based on a research project to monitor the temperature profile along a power cable using the fibre optic Distributed Temperature Sensing (DTS) technology. Based on the temperature measured by a DTS system, real time condition monitoring of power cables can be achieved. In this thesis, there are three main research themes. 1. Develop a DTS system for industrial applications. The entire hardware system and measuring software are developed to be an industrial product. Multiple functions are provided for the convenience of users to conduct temperature monitoring, temperature history logging and off-line simulation. 2. Enhance the robustness of the DTS system. An algorithm for signal compensation is developed to eliminate the signal fluctuation due to disturbance from the hardware and its working environment. It ensures robustness of the system in industrial environments and applicability to different system configurations. 3. Improve the accuracy of the DTS system. A calibration algorithm based on cubic spline fitting is developed to cope with non-uniform fibre loss in the system, which greatly improved the accuracy of the temperature decoding in real applications with unavoidable nonlinear characteristics. The developed DTS system and the algorithms have been verified by continuous experiments for about one year and achieved a temperature resolution of 0.1 degree Celsius, a spatial resolution of 1 meter, and a maximum error of 2 degree Celsius in an optic fibre with the length of 2910 metres.