A unique Raman spectroscopic investigation combining a number of different techniques has been conducted in situ on the composition of the passive film on iron, both during its growth in 0.05 M NaOH by potentiodynamic polarization and during localized breakdown by pitting after addition of 0.05 M NaCl. There are differing theories for the mechanism of pit initiation and formation in the passive film on iron, and while these are in part due to different environmental factors, they are also influenced by differing theories for the nature of the passive film. The detailed information obtained in this study corroborate the two layer model for the passive film on iron, with γ-Fe2O3 forming the inner layer and the outer layer consisting of δ-FeOOH, α-FeOOH, γ-FeOOH, other components such as Fe(OH)2 and other intermediates. In the passive region of anodic polarization the film became increasingly hydrated with increasing anodic potential and with increased cycles became amorphous, comparing well with the Hydrated Polymeric Oxide model. Pre-resonance enhancement of the Raman bands of iron oxides and particularly iron oxy-hydroxides was afforded by excitation at 636.4 nm, and particularly at low wavenumbers. The use of Multivariate Curve Resolution with Alternating Least Squares (MCR-ALS) enabled determination of the relative amounts of the iron oxide and oxy-hydroxide components from the complex spectra recorded during potentiodynamic polarization. The amount of water incorporated in the passive film under the same conditions was also monitored in situ at similar potentials using excitation at 514.5 nm. Addition of chloride ions resulted in an increase in hydration and a change of the composition of the passive film to comprise mainly β-FeOOH and Green complex with some γ-Fe2O3 and γ-FeOOH. At the pitting potential significant changes in the composition occurred along with reduction in hydration, so that re-passivation could no longer be maintained at the same rate as dissolution by the chloride ions, enabling stable pitting. These observations indicate that water plays a protective role in the passive film and reinforce the mechanisms for pit initiation based on the De-passivation–Re-passivation theory and Chemical Dissolution theory.

This thesis investigates Raman spectra of novel glasses and their correlation with structure for Raman gain applications. Raman gain for all-optical amplification by fibers depends significantly on the cross section for spontaneous Raman scattering allowing to compare signal strength and spectral coverage. We also investigate the relationship between glass structure and the Boson peak (enhancement of the low-frequency vibrational density of states) and report new inelastic neutron scattering spectra for niobium-phosphate glasses. Polarization resolved Raman spectra of glasses based on tellurite and phosphate formers have been measured from 6 – 1500 cm-1 using an excitation wavelength of 514 nm. The Tellurite glasses exhibit Raman Spectra at least 10 times more intense, are more spectrally uniform and possess spectral bandwidths more than a factor of two wider than fused silica. Assignments of the vibrational bands are presented and the compositional dependence of the spectra is discussed with respect to the molecular structure. Significantly high Boson peaks were found in the frequency range from 30-100 cm-1. The Raman gain curves were calculated from the polarized spontaneous Raman spectra. In particular, they show broad and flat band in the low frequency region (50-400 cm-1) suggesting that these glasses may be useful for Raman gain applications extending to very low frequencies. The inelastic neutron scattering spectra of the niobium-phosphate glasses display a pronounced low-frequency enhancement of the vibrational density of states. By averaging over the full accessible wavevector range we obtain an approximate spectral distribution of the vibrational modes. Through direct comparison with the Raman spectra we determine the Raman coupling function which shows a linear behavior near the Boson peak maximum. Possible mechanisms contributing to the low frequency Raman band such as disorder-induced irregular vibrational states are discussed.

Carbon Nanotubes (CNTs) have been the subject of intense research for their potential to improve a variety of material properties when developed as nano-composites. This research aims to address the challenges that limit the ability to transfer the outstanding nano-scale properties of CNTs to bulk nano-composites through Raman characterization. These studies relate the vibrational modes to microstructural characterization of CNT composites including stress, interface behavior, and defects. The formulation of a new fitting procedure using the pseudo-Voigt function is presented and shown to minimize the uncertainty of characteristics within the Raman G and D doublet. Methods for optimization of manufacturing processes using the Raman characterization are presented for selected applications in a polymer multiwalled nanotube (MWNT) composite and laser-sintered ceramic-MWNT composite. In the first application, the evolution of the MWNT microstructure throughout a functionalization and processing of the polymerMWNT composite was monitored using the G peak position and D/G intensity ratio. Processing parameters for laser sintering of the ceramic-MWNT composites were optimized by obtaining maximum downshift in stress sensitive G-band peak position, while keeping disorder sensitive D/G integrated intensity ratio to a minimum. Advanced Raman techniques, utilizing multiple wavelengths, were used to show that higher excitation energies are less sensitive to double resonance Raman effects. This reduces their influence and allows the microstructural strain in CNT composites to be probed more accurately. iii The use of these techniques could be applied to optimize any processing parameters in the manufacturing of CNT composites to achieve enhanced properties.

Functional properties of biological molecules and cells are affected by environmental parameters such as temperature and pressure. While Raman spectroscopy provides an intrinsic probe of molecular structural changes, the incorporation of a microscope enables studies of minuscule amounts of biological compounds with spatial resolution on a micron scale. We have developed a novel setup which combines a Raman microscope and a high pressure cell. A micro-capillary made out of fused silica simultaneously serves as the supporting body and the optical window of the pressure cell. The cell has been tested over the pressure range from 0.1 to 4 kbar. Raman spectra of less than 100 nanoliter amount of amino acid and protein solutions have been measured in the micro-capillary high pressure cell. It is also demonstrated that the setup is well suited for spectrally resolved fluorescence measurements at variable pressure.

In 2018 ESA and NASA plan to send the ExoMars rover to the Martian surface. This rover is planned to have a suite of analytical equipment that includes a Raman spectrometer. In this context, an evaluation of Raman spectroscopy as an analytical tool for interplanetary studies is investigated. The preparation techniques for appropriate inorganic and organic mixtures are interrogated. Methods are investigated to optimize the homogeneity of over 50 samples involving mineral phases; calcite, gypsum and goethite and selected organic biomolecular systems; anthracene, naphthalene and beta-carotene. From mixtures produced of these organic and inorganic materials differences between homogeneity of the samples is observed. Different mixing techniques are investigated to reduce this, however all the samples display variation on a micron scale. To resolve this issue a grid system of 9 points is implemented on solid samples and solutions are used to produce standards. The standards are devised using a range of instrument validation parameters for comparison between commercially available spectrometers and the prototype instrument. From these standards a prototype instrument is optimized for data acquisition and an evaluation procedure for instrument performance is established. The prototype Raman spectrometer is evaluated to match the specifications of the spectrometer on board ExoMars rover. A range of astrobiological relevant samples are interrogated; geological samples, biomarkers, cellular systems and bio-geological inclusions. From these samples detection of organics is observed to be only possible, with Raman spectroscopy where organics are localised in high concentrations, upon grinding and mixing geological inclusions Raman spectroscopy is unable to detect the organic components. / Appendices 3 and 4 are full text of the articles which are referenced in the text, but the published copy is not allowed to be displayed under copyright restrictions and are not included with this online thesis.

京都大学 / 0048 / 新制・論文博士 / 博士(理学) / 乙第12798号 / 論理博第1538号 / 新制||理||1566(附属図書館) / 80842 / (主査)教授 北川 宏, 教授 吉村 一良, 教授 竹腰 清乃理 / 学位規則第4条第2項該当 / Doctor of Science / Kyoto University / DGAM

Analyzing the constituents of meteorites has played an important role in forming the contemporary theories of solar system evolution, planets formation, and stellar evolution. Meteorites are often a complex mixture of common rock forming silicates, such as olivines and pyroxenes, with a range of exotic species including hydrated silicates, and in some cases organic compounds. We used Micro-Raman spectroscopy to analyze the compositions of three carbonaceous chondrites: NWA852, Murchison and Allende. Raman spectra were measured using laser sources with different excitation wavelengths: HeNe 633 nm and Nd:YAG 532 nm. We were able to detect 9 minerals in NWA852, 3 minerals in Murchison and 4 minerals in Allende. Some of these minerals like pyrite in NWA852 and magnetite in NWA852 and Murchison provide evidence for potential previous organic life. Other minerals like ringwoodite in Allende and lizardite in NWA852 reveal information about previous astrophysical and geological events experienced by the meteorites. The detection of graphite in the Murchison and Allende reveals information about the microstructure of these meteorites.

The increase in antibacterial resistance has placed the issue of microbial multi-drug resistance on a global stage (Gurunathan, 2019). This issue poses a threat to human and animal health as well as to the environment (Aslam et al., 2018). It affects not only the efficacy of treatment but also how those treatments are conducted (Friedman, Temkin, & Carmeli, 2016). As a result of this ongoing threat, new treatments that have potent effects on bacteria are necessary. One scientific response to this issue has been the development of multifunctional nanoparticles (NPs)(H. Wang et al., 2018). NPs have the ability to be utilized by its varying modes of action and compatibility with other forms of treatments (Alavi & Rai, 2019). This advantage, when successful, would allow for the lowering of dosage and frequency of treatments required to achieve bacteria-killing (Alavi & Rai, 2019). Despite a plethora of proposed designs for the improvement of antibacterial treatment, questions remain concerning the mode of action of these new agents. The aim of this study is to develop a protocol facilitating the identification of modes of action of newly formulated antibacterial agents. Our hypothesis is that different modes of action will have distinct effects on the morphology and composition of the cells. To test this, we characterized the structural, physical and molecular changes of a model system, E. coli., before and after treatments using antibiotics with known modes of action. We selected two bactericidal antibiotics: colistin which is a membrane disrupting antibiotic, and streptomycin which is a protein inhibiting antibiotic (Santo-Domingo, Chareyron, Broenimann, Lassueur, & Wiederkehr, 2017; Sun et al., 2019; Thummeepak, Kitti, Kunthalert, & Sitthisak, 2016). We discuss the protocol development and the significant differences observed in the bacterial responses as well as the limitations of the envisioned approach. We conclude by providing a perspective of the impact our findings are expected to have on evaluating new engineers NP treatments.

An impact of nitrogen, phosphorus and potassium fertilizers on the concentration changes of carotenoid pigments in the Indigofera tinctoria plant by using Raman spectroscopic techniques is studied. Three different concentration levels of the fertilizers with a normal supply as control were added to the plants at two stages. The Raman spectra were taken to determine the carotenoid concentration level changes in the plant leaves in vivo. The ring-stretching mode are the Raman spectroscopic signatures for the carotenoid pigment and its magnitude increased significantly (over 170%) for the case of phosphorus and potassium fertilizers. The effect from the nitrogen fertilizer was detected to be about 130% in comparison with the corresponding control plants. This study has a potential application for the increased extraction of the indigotin dye from plants for the medical and textile industries.

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