Dissertations / Theses on the topic 'Raman spectroscopy'
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Li, Yun-Thai. "Tip-enhanced Raman spectroscopy." Thesis, University of Cambridge, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.609992.
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Patil, Raj. "Deep UV Raman Spectroscopy." Thesis, The University of Arizona, 2016. http://hdl.handle.net/10150/613378.
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This thesis examines the performance of a custom built deep UV laser (257.5nm) for Raman spectroscopy and the advantages of Raman spectroscopy with a laser in the deep UV over a laser in the visible range (532 nm). It describes the theory of resonance Raman scattering, the experimental setup for Raman spectroscopy and a few Raman spectroscopy measurements. The measurements were performed on biological samples oak tree leaf and lactobacillus acidophilus and bifidobacteria from probotioc medicinal capsules. Fluorescence free Raman spectra were acquired for the two samples with 257.5 nm laser. The Raman spectra for the two samples with a 532nm laser was masked with fluorescence. Raman measurements for an inorganic salt sodium nitrate showed a resonance Raman effect with 257.5 nm laser which led to enhancement in the Raman intensity as compared to that with 532 nm laser. Therefore we were able to demonstrate two advantages of deep UV Raman spectroscopy. First one is the possibility of acquiring fluorescence free spectra for biological samples. Second is the possibility of gaining enhancement in Raman intensity due to resonance Raman effect. It was observed that 257.5 nm laser requires optimization to reduce the bandwidth of the laser to get better resolution. The 257.5 nm laser also needs to be optimized to obtain higher power to get better signal to noise ratio. The experimental setup can also be further improved to obtain better resolution. If the improvements required in the setup are implemented, the deep UV Raman setup will become an important tool for spectroscopy.
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Nathaniel, Todd. "Spatial heterodyne Raman spectroscopy." Thesis, University of Surrey, 2011. http://epubs.surrey.ac.uk/810642/.
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Bergqvist, Saga. "Raman spectroscopy in neurosurgery." Thesis, Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-78665.
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Brain tumors or brain cancer is a disease than affects people of all ages. The median age of a person living with a brain tumor is 60 years, it is however a disease that affects children and young adults in high grade. Brain cancer is the second most common type of cancer among children and is also the most common cause of cancer related death among this group. To ensure that the damages on the brain is as small as possible, it is important that a tumor can be diagnosed and removed as early as possible. Previous methods of diagnosis is based on biopsy where a part of the tumor is removed and examinated by a pathologist. This is a time consuming process that also is biased by the human factor, there is therefore a need for a method that can be used \textit{in situ} with an unbiased result. One method that have shown great promise is photensitation with 5-Aminolevoluic acid (5-ALA). However, this method have shown to only work properly on tumors of high malignancy in adults. As a comlpiment to photosentisation, Raman spectroscopy have shown good promise in previous studies. This study was conducted to investigate the use of Raman spectroscopy as a tool for \textit{in situ} brain tumor diagnostics. The use of Raman spectroscopy was tested by comparing two previously performed studies, where they looked at a number of Raman bands from biological markers that are known to change in cancerous tissue as well as the intensity ratio between some Raman bands. A measurement system for Raman spectroscopy was designed and built at Luleå University of Technology where the system were evaluated on tissue samples from conventional meat i.e. pork and beef to ensure that is was possible to achieve spectroscopic information of protein and lipid content in tissue. The measurement system was then transported to Linköpings University where the measurements on six brain tissue samples where performed. The samples came from five different tumors of which one tumor was thought to come from a high malignant tumor based on preliminary histopathological analysis and four from low malignant or benign tumors. Two samples where obtained from the high malignant tumor that was photosentisized with 5-Aminolevoluic acid and one of the samples where illuminated with blue light prior to the Raman spectroscopic measurements. The spectroscopic data was pre-processed before analysis using conventional methods. The analysed spectra from the brain tissue samples showed presence of the Raman bands associated with brain tissue. It was also possible to see Raman bands associated with 5-ALA in the samples that had been photosentisized, however when the tissue had been illuminated with blue light it was also possible to see distinct Raman bands associated with brain tissue. One tissue sample also showed presence of reduced Neuroglobin (NGB). The composition of NGB is also known to change in tumorous tissue and could therefore be used in future work as a biological marker for brain tumors. When comparing the results obtained in this study with the two previously performed, one of the studies showed that two samples were from a tumor of high malignancy and the other from low malignant or benign tumors. This result was in accordance with the preliminary histopathological assessment of the brain tissue samples. When comparing the results to the other study, the results where contradictory and indicated that all tissue samples where from low malignant or benign tumors. The conclusion of this work is that Raman spectroscopy is possible to use as a tool for brain tumor diagnostics. It would be desirable to use this method in combination with 5-ALA staining since the Raman bands from brain tissue could be resolved when the tissue had been illuminated with blue light.Hjärntumörer kan drabba människor i alla åldrar, medelåldern för människor som lever med en hjärntumör är 60 år, men det är ett tillstånd som även drabbar barn och unga i stor utsträckning. Hjärntumörer är den näst vanligaste cancerformen hos barn och är även den främsta orsaken till cancerrelaterad död i den åldergruppen. För att minimera skadorna på hjärnan är det viktigt att en tumör kan lokaliseras och tas bort så tidigt som möjligt. De metoder som används idag bygger framför allt på biopsi, där en del av tumören tas bort och undersöks av en histopatalog. Det är en process som tar lång tid och även påverkas av den mänskliga faktorn, det finns därmed ett behov av en metod som kan avändas \textit{in situ} som ger ett resultat som inte påverkas av den mänskliga faktorn. En metod som har visat lovande resultat är fotosensibilisering med 5-Aminolevulinsyra (5-ALA). Desvärre har den metoden bara visat sig fungera bra för högmaligna tumörer hos vuxna. Som ett komplement till fotosensibilisering har Ramanspektroskopi visat lovande resultat i tidigare genomförda studier. Det här arbetet genomfördes för att undersöka användningen av Ramanspektroskopi som ett verktyg för diagnostisering av hjärntumörer. Som grund användes två tidigare genomförda studier där de undersökte Ramanband från biologiska markörer i hjärnvävnad som ändras i cancerogen vävnad. De undersökte även hur den biokemiska sammansättningen av hjärnvävnaden ändrades genom att jämföra intensiteten av olika Ramanband. Ett mätsystem för Ramanspektroskopi designades och byggdes upp på Luleå Tekniska Universitet där det även testades på vävnad från kött (fläsk och biff). Därefter transporterades mätsystemet till Linköpings Universitet för att genomföra mätningar på sex olika vävnadsprov från fem hjärntumörer av olika malignitet. Baserat på en preliminär histopatalogisk bedömning var en av tumörerna högmalignt och de fyra andra tumörerna var antingen lågmalignta eller benigna. Två av proverna som undersöktes kom från den högmalignta tumören som även var fotosensibilierad med 5-Aminolevulinsyra, varav ett av proverna var belyst med blått ljus innan de Ramanspektroskopiska mätningarna genomfördes. Innan resultatet från Ramanspektroskopiska mätningarna analyserades behandlades datan med konventionella metoder i MatLab. I de resulterade spektrumen gick det att se tydliga Ramanband associerade med hjärnvävnad. Det gick även att se Ramanband associerade med 5-ALA i de två prover som var fotosensibiliserade och i det provet som var belyst med blått ljus innan de spektroskopiska mätningarna gjordes gick det även att se tydliga Ramanband associerade med hjärnvävnad. När resultatet analyserades gick det även att se spektra associerat med reducerat Neuroglobin (NGB) i ett av proverna. Sammansättningen av NGB är också någonting som ändras i cancerogen vävnad och skulle därför också kunna användas som en bilogisk markör för hjärntumörer i framtida studier. När resultaten från den här studien jämfördes med de tidigare studierna indikerade den ena studien att två av vävnadsproverna kom från en högmalignt tumör och att de resterande fyra från lågmaligna eller benigna tumörer, vilket stämmer överens med den preliminära diagnosticeringen av tumörerna. När resultatet istället jämfördes med den andra studien stämde inte resultatet lika bra med den preliminära diagnosticeringen av tumörerna. Metoden presenterad av Zhou m.fl. indikerade att alla tumörer kom från lågmaligna eller benigna tumörer. Slutsaten av det här arbetet är att Ramanspektroskopi skulle kunna användas som en metod för diagnosticering av hjärntumörer. Metoden skulle även fungera bra som ett komplement till fotosensibilisering med 5-ALA eftersom att det var möjligt att se Ramanband associerade med hjärnvävnad när vävnaden hade belysts med blått ljus.
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Cancado, Luiz Gustavo de Oliveira Lopes. "Raman spectroscopy of nanographites." Universidade Federal de Minas Gerais, 2006. http://hdl.handle.net/1843/IACO-6W8NYM.
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This work presents the application of the Raman spectroscopy for the study and characterization of nanographite systems. We report the ¯rst detection of nanographite ribbons on a highly oriented pyrolytic graphite substrate by Raman spectroscopy. We found a way to di®erentiate the Raman signal of the ribbon from that of the substrate, the Raman signal of the ribbon having the same order of magnitude as the one of the substrate, despite the much smaller number of illuminated carbon atoms (»10¡3). The results show that these structures present van Hove singularities in the electronic density of states due to quantum con¯nement into their 1D structure. In another experiment, we use micro-Raman scattering to determine the arrangement of carbon atoms in a graphite edge. Theedge of a semi-in¯nite plane can be considered as a one-dimensional defect, leading to unusual defect-induced Raman scattering that turns out to be structurally selective. In this case, Raman scattering can be used to de¯ne the orientation of the carbon hexagons with respect to the edge of a graphite plane, in the so called armchair and zigzag arrange-ments. These two experiments involve the ¯rst detection of the anisotropy in the optical absorption of graphite, giving strong support to previous theoretical predictions. We also present a systematic study of the ratio between the integrated intensities of the disorder-
induced D band and the ¯rst-order allowed G band (ID=IG) in the Raman spectra of nanographite samples with di®erent crystallite sizes (La) and using di®erent excitation laser energies (wavelengths). The crystallite size La of the nanographite samples were obtained both by X-ray di®raction using synchrotron radiation and directly from scan-
ning tunneling microscopy images. A general equation for the determination of La using any laser energy in the visible range is obtained. Moreover, we performed measurements
of the absolute intensities of individual features in the Raman spectra of nanographites,showing the dependence of these features on the excitation laser energy and crystallite size.Resumo: No presente trabalho investigamos alguns efeitos físicos que acontecem na estrutura e evolução estelar. Focalizamos nossa atenção em estrelas de baixa massa na pré-sequência principal. Incluímos alguns efeitos físicos no código de estrutura e evolução estelar ATON2.3, escrito pelo Dr. Ítalo Mazzitelli (1989) e posteriormente modificado pelo Dr. Luiz Themystokliz Sanctos Mendes (1999b) para adicionar os efeitos de rotação e redistribuição interna de momento angular. Com o objetivo de economizar tempo computacional, introduzimos o mecanismo de parada de controle (checkpoint), que permite iniciar uma dada execução em um estágio de evolução intermideário, desde que os passos iniciais tenham sido devidamente registrados. Essas modificações foram feitas juntamente com um controle completo de variáveis não inicializadas, precisão e reestruturação do programa, visando futuramente paralelizar o código. Introduzimos efeitos combinados de rotação e forças de maré na configuração de equilíbrio das estrelas. Estes efeitos perturbadores, contidos na função potencial total, desviam a forma da estrela da aproximação esfericamente simétrica. Usamos o método de Kippenhahn & Thomas (1970), posteriormente aperfeiçoado por Enda & Sofia (1976). À função potencial obtida por estes autores, adicionamos termosrelacionados à forças de maré e àqueles relacionados à parte não simétrica do potencial gravitacional devido à distorção que tais forças causam na figura da estrela. Seguindo esta aproximação, corrigimos as equações constitutivas a fim de obter uma configuração estrutural de uma estrela distorcida. Cálculos de constantes de estrutura interna e raios de giração foram incluídos no código. Várias trilhas evolutivas foram geradas com os novos modelos, incluindo as quantidades mencionadas acima. Os novos modelos foram testados através de dados observacionais das dimensões absolutas, taxa de movimento apsidal e abundância de lítio das componentes do sistema binário eclipsante EK Cephei. No presente trabalho, também apresentamos estimativas teóricas do convective turnover time, Tc e Números de Rossby, Ro, para estrelas com massas semelhantes à massa solar, com rotação e na pré-sequência principal. Ro está relacionado com a força magnética na teoria do dínamo e, pelo menos para estrelas na seqüência principal, observa-se uma correlação entre rotação e atividade estelar. Incluímos também a possibilidade de utilizar modelos de atmosferas não cinza, com o objetivo de seguir a evolução estelar de estrelas de baixa massa desde estágiosbem iniciais, caracterizados por baixa gravidade. Adotamos os modelos NextGen e ATLAS9 de atmosferas estelares. Usando os nossos novos modelos não-cinza, geramos vários conjuntos de trilhas evolutivas, partindo da pré-sequência principal. Tais trilhas foram usadas para investigar algumas propriedades físicas e rotacionais de estrelas jovens na Nebulosa de Orion. Comparações entre resultados teóricos e dados observacionais, permitiram-nos obter informações sobre esta classe de objetos, principalmente no que diz respeito à distribuição inicial de momento angular. A interpretação dos dados depende fortemente das considerações físicas feitas no modelos, sendo a eficiência da convecção a mais importante. Nossa análise indica que um segundo parâmentro é necessário para descrever a convecção na pré-sequência principal. Tal parâmetro está possivelmente relacionado ao efeito estrutural de um campo magnético gerado por efeito dínamo.
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SPEISER, EUGEN. "Raman spectroscopy on nanostructures." Doctoral thesis, Università degli Studi di Roma "Tor Vergata", 2008. http://hdl.handle.net/2108/566.
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One of the most current and also most promising fields of research in solid state physics is that of nano-structured materials. In particular, there is a great interest in nanostructured semiconductors, thanks to the latest developments in preparation techniques. These techniques allow to prepare nano-sized semiconductors with excellent crystalline structure and most often also with epitaxially determined orientations with respect to a template.
The interest in nano-structures is triggered by the discovery that their physical properties (electronic, optical, thermodynamical) are different from those of the corresponding bulk material due to confinement. Consequently, the size becomes a new design parameter for new electronic and optoelectronic devices, for example.
The goal of this work is to study nano-structures by optical methods, especially by Raman spectroscopy. 1-dimensional nano-structures are the main focus because of their recently intensively investigated and improved growth mechanisms. This research enables the synthesis of nano-materials of high crystalline quality, controlled orientation and size.
To obtain measurements from 1- dimensional (quantum wires, nanorods, nanotubes) and 0-dimensional nanostructures (quantum dots)—in contrast to well-investigated 2- dimensional quantum wells—an additional requirement for the measurement technique is that the probe must provide lateral resolution in the nanometer range. This requirement excludes or limits many of the standard surface science techniques and is especially true for the standard optical tools with diffraction limited spatial resolution in the sub-micrometer range. If possible, samples with modified growth process parameters are chosen in order to reduce the spatial density of the nanostructures in a way that only one structure is contained in the probing area. The goal is to exclude averaging of their properties by summing contributions from different structures. This is achieved also by using confocal microscopy spectroscopy providing diffraction limited spatial resolution in the micrometer range (~ 1μm). Confocal micro Raman measurements are performed on low dimensional semiconductor structures such as Si, GaAs, AlGaAs, SnO2 and ZnO nanowires.
Another important goal of this work is to design and build a new experimental set-up in order to extend the spatial resolution to the nanometer range, exploiting near field optics in combination with scanning probe microscopy (Scanning Tunnelling Microscopy and Atomic Force Microscopy). This enables simultaneous measurements of topography and spectroscopy, thus permitting direct correlation of morphological and optical properties. Moreover the internal structure of nano-samples can be made accessible by optical spectroscopy. For this purpose an apertureless scanning near field optical microscope (a-SNOM) set-up was developed. Scanning Probe Microscopy (SPM) equipment was integrated into a confocal Raman spectroscopy apparatus and preliminary test measurements are performed.
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McGoverin, Cushla Maree, and n/a. "Raman spectroscopy of complex mixtures." University of Otago. Department of Chemistry, 2008. http://adt.otago.ac.nz./public/adt-NZDU20081103.112612.
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This thesis presents several Raman spectroscopic studies of bovine milk-derived products (skim and whole milk powder, anhydrous milk fat, processed cheese and soy cheese made from milk protein). Raman spectroscopy, unlike infrared spectroscopy (both mid- and near-infrared), has not been widely used as an analytical tool within the dairy industry. The purpose of this project was to assess the utility of Raman spectroscopy in several dairy industry relevant problems. FT-Raman spectroscopy coupled with partial least squares (PLS) reliably predicted the concentration of fat and protein within whole milk and protein within skim milk powders as evidenced by ratios of prediction to deviation in excess of three. It was shown that sample geometry did not significantly affect the calculated predictive models, thereby allowing the simplest, quickest method of sample presentation to be utilised without harming quantification model efficacy.
The fat fraction of milk was further investigated, and it was shown that Raman spectra collected from anhydrous milk fat samples were a good basis for solid fat content (SFC) determination. Such spectra were collected when the samples were held at 40 �C, pretreated by baselining and area normalisation, and analysed using PLS with modified jack-knifing (PLS1-JK). Triacylglycerol class concentrations were also well predicted by PLS1-JK models developed from Raman spectroscopic data. Resonance enhancement of β-carotene within fat was shown to have little effect on the reliability of the optimal prediction model when compared to SFC Raman quantification.
Raman microscopic mapping for heterogeneity description of processed cheese and soy cheese mimics was examined. The FT-Raman milk powder constituents study had shown fat and protein Raman spectra within complex dairy mixtures could be distinguished, hence this utility was applied to mapping of cheese systems. Univariate, principal components analysis and multivariate curve resolution methods of analyses were compared; as expected the more complex samples required multivariate methods of analyses. Raman microscopic mapping was not a time efficient method in comparison to the standard method of confocal laser scanning microscopy. However, Raman spectroscopic mapping is a more universal technique which allowed the presence of an unexpected localised constituent within the soy cheese mimics to be observed. It was proposed that this constituent was a crystalline form of a short saturated fatty acid.
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Castillo, Carolina Graciela. "Biological applications of raman spectroscopy." Diss., Georgia Institute of Technology, 1993. http://hdl.handle.net/1853/30414.
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O'Grady, Noelle Antoinette. "Raman spectroscopy of fluorescent samples." Thesis, Queen's University Belfast, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.246542.
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Thomson, Grant. "Forensic applications of Raman spectroscopy." Thesis, University of Leeds, 2002. http://etheses.whiterose.ac.uk/395/.
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The forensic applications of Raman spectroscopy have been explored and extended using the development of novel sampling techniques and task-specific instrumentation described in this thesis. The phenomenon of Raman scattering, enhanced Raman scattering and their relevance in forensic investigations was reviewed. Particular emphasis was placed on current applications, experimental considerations relevant to in-situ Raman sampling and the deficiencies of instrumentation commercially available at the time. It was concluded that the development of novel, optimised instrumentation was essential in the application of Raman spectroscopy to portable forensic applications. The feasibility of achieving molecularly-specific and sensitive detection of TNT vapour using waveguide-enhanced, surface-enhanced resonance Raman spectroscopy was investigated using reference spectra measured using a calibrated optical system provided by a collaborator. Improvements in signal-to-noise ratio afforded by employing waveguide-enhanced sampling, higher excitation power, long integration times and an improved spectrometer design were modelled, experimentally verified, and used to predict a detection limit of 10-16g for saturated vapour-phase TNT. The theoretical performance of the optical instrument is described and verified using experimentally measured data. The feasibility of conducting specific and sensitive long-range stand-off covert observation operations against unsuspecting targets in compliance with the UK Regulation of Investigative Powers act was established using a task-optimised laboratory simulation. Using a 5mW visible excitation, short integration times (under 20s) and multiplex detection it was possible to detect and identify a tagged object from a range of up to 50m. The feasibility study yielded a robust prototype handheld system comprising a modified telephoto camera with the integrated capability of sample discrimination using Raman spectroscopy. The instrument design is described.
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Weigel, Alexander. "Femtosecond stimulated resonance Raman spectroscopy." Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät I, 2011. http://dx.doi.org/10.18452/16302.
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Femtosekundenaufgelöste Ramanspektroskopie ist ein leistungsfähiges Werkzeug, um die Schwingungsentwicklung eines angeregten Chromophors in Echtzeit zu studieren. In dieser Arbeit wurde ein durchstimmbares Ramanspektrometer mit 10 cm-1 spektraler und 50--100 fs zeitlicher Auflösung entwickelt und für eine Anwendung auf flavinbasierte Photorezeptoren optimiert. Es wird der Einfluß der Resonanzbedingungen auf das transientes Ramanspektrum charakterisiert. Die Dynamik des angeregten Zustandes wird zuerst für den Modellphotoschalter Stilben untersucht, ausgehend sowohl vom cis-, als auch vom trans-Isomer. Intensitätsabnahme, spektrale Verschiebung und Bandenverschmälerung liefern Einblicke in die Schwingungsrelaxation des angeregten Chromophors. Wellenpaketbewegung und anharmonische Kopplung werden als Oszillationen beobachtet. Für das "Mutter"-Cyanin 1,1''-Diethyl-2,2''-pyridocyaniniodid wird die Isomerisierung bis in den Grundzustand verfolgt. Ramanspektren des Franck-Condon-Zustandes, des intermediär gebildeten heissen Grundzustandes und der Isomerisierungsprodukte werden erhalten. Als Grundlage für Experimente an Flavoproteinen werden die Eigenschaften des angeregten Flavinchromophors in Lösung untersucht. Transiente Absorptions- und Fluoreszenzexperimente weisen auf den Einfluss dynamischer polarer Solvatation hin. Es werden Ramanspektren des angeregten Zustandes von Flavin aufgenommen und die Schwingungsbanden zugeordnet. Populationsverminderung durch den Ramanimpuls wird als potentielles Artefakt in zeitaufgelösten Messungen identifiziert; der Effekt wird aber auch genutzt, um Wellenpaketbewegung im angeregten Zustand zu markieren. Die Photorezeptormutanten BlrB-L66F und Slr1694-Y8F werden mit transienter Absorption studiert. Dabei wird die Bildung des Signalzustandes und Flavinreduktion durch ein Tryptophan beobachtet. Die Anwendung des entwickelten Ramanspektrometers auf biologische Proben wird in einem ersten Experiment an Glucose Oxidase demonstriert.Femtosecond stimulated Raman spectroscopy is a powerful tool that allows to study the structural relaxation of an excited chromophore directly in time. In this work a tunable Raman spectrometer with 10 cm-1 spectral and 50-100 fs temporal resolution was developed, and the technique was advanced towards applications to flavin-based proteins. With this device the influence of resonance conditions on the transient Raman spectrum is characterized. Excited-state dynamics is first investigated for the model photoswitch stilbene, starting from both the cis and the trans isomers. Decay, spectral shift, and narrowing of individual bands provide insight into the vibrational relaxation of the excited chromophore. Wavepacket motion and anharmonic coupling is seen as oscillations. Isomerization is followed to the ground state for the "parent" cyanine 1,1''-diethyl-2,2''-pyrido cyanine iodide. From a global analysis, Raman spectra for the Franck-Condon region, the intermediately populated hot ground state, and the isomerization products are obtained. As a basis for experiments on flavoproteins, the excited-state properties of the pure flavin chromophore are studied in solution. Transient absorption and fluorescence experiments suggest an influence of dynamic polar solvation on the electronic properties of the excited state. Raman spectra from the flavin excited state are recorded and the vibrational bands assigned. Population depletion by the Raman pulse is identified as a potential artefact, but the effect is also used to mark wavepacket motion in the excited state. The photoreceptor mutants BlrB-L66F and Slr1694-Y8F are studied by transient absorption; signaling state formation and flavin reduction by a semiconserved tryptophan are seen, respectively. The application of femtosecond Raman spectroscopy to biological samples is demonstrated in a first experiment on glucose oxidase.
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Lee, Nam-Heui. "Extending Raman spectroscopy to the nanoscale." Akron, OH : University of Akron, 2007. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=akron1172680006.
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Dissertation (Ph. D.)--University of Akron, Dept. of Polymer Science, 2007."May, 2007." Title from electronic dissertation title page (viewed 04/07/2008) Advisor, Mark D. Foster; Committee members, Alexei P. Sokolov, Darrell H. Reneker, Ali Dhinojwala, Rex D. Ramsier; Department Chair, Mark D. Foster; Dean of the College, George R. Newkome; Dean of the Graduate School, George R. Newkome. Includes bibliographical references.
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U, Mahaboob Pasha. "Raman spectroscopy of BaTiO3 based ceramics." Thesis, University of Sheffield, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.527217.
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Freihofer, Gregory J. "Enhancing CNT-composites with Raman spectroscopy." Master's thesis, University of Central Florida, 2011. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/4763.
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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 polymer-MWNT 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. The use of these techniques could be applied to optimize any processing parameters in the manufacturing of CNT composites to achieve enhanced properties.ID: 030646203; System requirements: World Wide Web browser and PDF reader.; Mode of access: World Wide Web.; Thesis (M.S.A.E.)--University of Central Florida, 2011.; Includes bibliographical references (p. 84-94).
M.S.A.E.
Masters
Mechanical and Aerospace Engineering
Engineering and Computer Science
Aerospace Engineering; Space System Design and Engineering Track
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Boyce, Paul John. "Raman spectroscopy of II-VI semiconductors." Thesis, University of East Anglia, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.357210.
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Hard, Andrew Philip. "Sensing and analysis with Raman spectroscopy." Thesis, University of East Anglia, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.268552.
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Gil, Gustavo Adolfo. "Online Raman spectroscopy for bioprocess monitoring." Thesis, Massachusetts Institute of Technology, 2005. http://hdl.handle.net/1721.1/36757.
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Thesis (M. Eng. and S.B.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2005.Author received the S.B. degree, June 2005 and the M. Eng. degree, Sept. 2005.
Includes bibliographical references (p. 195-202).
Online monitoring of bioprocesses is essential to expanding the potential of biotechnology. In this thesis, a system to estimate concentrations of chemical components of an Escherichia Coli fermentation growth medium via a remote fiber-optic Raman spectroscopy probe was studied in depth. The system was characterized to determine sources of instability and systematic error. A complete first-order error analysis was conducted to determine the theoretical sensitivity of the instrument. A suite of improvements and new features, including an online estimation of optical density and biomass, a method to correct for wavelength shifts, and a setup to increase repeatability and throughput for offline and calibration methods was developed accordingly. The theoretical and experimental ground work for developing a correction for spectrum distortions caused by elastic scattering, a fundamental problem for many spectroscopic applications, was laid out. In addition, offline Raman spectroscopy was used to estimate concentrations of fructose, glucose, sucrose, and nitrate in an oil palm (Elais guineensis) bioreaction. Finally, an expansion of optical techniques into new scale-up applications in plant cell bioprocesses, such as plant call differentiation was explored.
by Gustavo Adolfo Gil.
M.Eng.and S.B.
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Chau, Alexandra H. (Alexandra Hung) 1980. "Development of an intracoronary Raman spectroscopy." Thesis, Massachusetts Institute of Technology, 2009. http://hdl.handle.net/1721.1/49757.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2009.Includes bibliographical references (p. 167-177).
Atherosclerosis is a leading cause of death in the United States, with 1 in 5 deaths (500,000 annually) attributable to coronary artery disease alone. While the disease processes are not completely understood, it is believed that patient risk depends on a variety of factors including lesion structure, biomechanical behavior, and morphological and chemical composition. Raman spectroscopy, based on spectral analysis of inelastically scattered photons, is a nondestructive technique that yields detailed information about the chemical composition of the sample being interrogated. Intracoronary Raman spectroscopy can be performed via the use of a flexible, small diameter (< 2 mm) optical fiber probe to guide light to and from the arterial wall in situ. The fact that Raman scattering has inherently low signal intensity, combined with the need for a small diameter probe, makes it difficult to develop a probe with sufficient signal-to-noise for robust plaque diagnosis. This thesis addresses two approaches for increasing SNR: increasing Raman signal intensity and optimizing probe design. While most biological applications of Raman spectroscopy have been performed in the "fingerprint" region (Raman shifts between 400 and 1800 cm-1), the high wavenumber region (2700 - 3100 cm-1) offers distinct technical advantages, including increased Raman signal relative to the fluorescent background and potentially less fiber background. However, the high wavenumber region may yield different molecular information and thus have different diagnostic capability. In this thesis, we develop a benchtop Raman system capable of acquiring Raman spectra in both wavenumber regions.
(cont.) In contrast to previous work, which focused on plaque characterization based on the Raman spectrum from a single site within the plaque, our system utilizes a line imaging paradigm, in which we acquire Raman spectra at fixed intervals across the full cross-section of the plaque, creating a Raman line image. We use this benchtop system to acquire a database of Raman line images and corresponding histology for over sixty plaque specimens. Using this database, we compare the diagnostic capability of fingerprint and high wavenumber Raman spectroscopy for plaque characterization. Because of the small size requirement for an intracoronary probe, it is important to optimize the optical probe design to maximize collection efficiency and thus increase SNR. We develop and experimentally validate a simulation technique for modeling Raman probe performance (collection efficiency and sampling volume), as an aid to optimizing probe design. We also fabricate a 1.5 mm diameter probe and demonstrate it in vivo, using a human-swine xenograft model, in which diseased human coronary arteries are grafted onto a living swine heart. The results of this thesis provide insight on two approaches toward achieving a clinically viable intracoronary Raman spectroscopy system.
by Alexandra H. Chau.
Ph.D.
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Farhat, Hootan. "Raman spectroscopy of metallic carbon nanotubes." Thesis, Massachusetts Institute of Technology, 2010. http://hdl.handle.net/1721.1/59217.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2010.Includes bibliographical references (p. 101-108).
Metallic carbon nanotubes are one dimensional conductors that are both technologically promising for electronic applications, and scientifically interesting for studying the physics of low dimensional materials. In this thesis, we present a detailed study of the inelastic light scattering (Raman) spectrum of individual metallic carbon nanotubes, with a focus on the influence of electronic excitations and charged carriers. We have demonstrated that the frequency and linewidth of certain phonon modes of metallic carbon nanotubes depend strongly the Fermi energy, because they couple strongly to low lying electron hole pairs. Next, we report the first experimental observation of electronic Raman scattering in carbon nanotubes. This observation demonstrates that the same electron-hole pairs that participate in damping the optical phonons of metallic carbon nanotubes, may themselves scatter light, thus giving rise to an electronic Raman spectrum. An analysis of the Fermi level and laser energy dependence of the electronic Raman and phonon Raman contributions allows us to explain the asymmetric lineshape of the G-band phonon modes in terms of a Fano interference. In another experiment, we have shown that the charge-induced expansion and contraction of the the graphitic C-C bond length is different for metallic and semiconducting nanotubes. Finally, we have measured the Stokes and antiStokes intensities of the Raman modes in electrically contacted metallic nanotubes in order to determine their phonon populations during high-field electrical transport. The experiments reported here, have helped to clarify the origin of several features in the Raman spectra of metallic carbon nanotubes that have been heavily debated in recent years. These result also shed light on the way electronic excitations and charged carriers affect the physical properties of metallic carbon nanotubes.
by Hootan Farhat.
Ph.D.
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Hart, Prieto Maria Consuelo. "Applications of Raman spectroscopy to urology." Thesis, Cranfield University, 2006. http://dspace.lib.cranfield.ac.uk/handle/1826/8540.
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Raman spectroscopy is an optical technique that can interrogate biological tissues. In doing so it gives us an understanding of the changes in the molecular structure that are associated with disease development. The Kerr gating technique uses a picosecond pulsed laser and fast temporal gating of inelastically (Raman) scattered light. The tissue samples used were taken following fully informed consent and ethics approval. Bladder samples were obtained by taking a biopsy during a TURBT or TURP, prostate samples were taken during TURP and the liver and kidney (pigs) were bought at a supermarket. The bladder and prostate samples were snap frozen in liquid nitrogen and stored in an -80°C freezer until required for experimentation. The liver and kidney tissue were used fresh. The constituent samples were bought from Sigma – Aldrich. Multivariate and least squares analysis were used to ascertain the biochemical basis of the differing pathologies within the bladder and the prostate gland, as well as to test diagnostic algorithms produced by a colleague in our group. Depth profiling through the bladder and prostate gland was shown to be feasible by utilizing the Kerr gating technique as was the suppression of fluorescence from dark tissue (liver and kidney). We have shown for the first time, that we can utilise Raman spectroscopy to determine the biochemical basis of pathologies of the bladder and the prostate gland. With the help of the Kerr gating technique we also obtained spectra from different depths through them. We also suppressed fluorescence and resonantly enhanced Raman spectra from dark tissue. These have major implications in terms of understanding pathogenesis and disease progression and also the potential to accurately assess depth of tumour invasion.
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Wattanavichean, N. "Raman spectroscopy of molecular electronic junctions." Thesis, University of Liverpool, 2017. http://livrepository.liverpool.ac.uk/3006908/.
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Molecular Electronics uses molecules sandwiched between two metals as a model system to create tailored solutions for applications such as energy harvesting and sensing. Electrons tunnelling across such a junction are a↵ected by the properties of the molecule itself as well as the interaction between metal and molecule. In particular, charge transport is known to couple to molecular vibrations, which can act both to dissipate energy as well as increase conductance. This thesis therefore applies in-situ vibrational spectroscopies, surface-enhanced Raman scattering and vibrational sum frequency generation, to investigate molecular junctions. As a model system, 4-mercaptopyridine sandwiched between a gold surface and an elec- trochemically deposited second metal layer is used. Four aspects are studied in detail in this thesis. Chapter 3 presents a detailed study of surface enhanced Raman spectra of 4-mercaptopyridine on gold. All experimental vibrational modes are assigned and related to the symmetry of the adsorbed molecule with the help of density functional calculations. In particular, the e↵ect of hydrogen bonding on the ring breathing modes of adsorbed mercaptopyridine is revealed for the first time. In chapter 4, surface-enhanced Raman spectroscopy is used to identify a spectroscopic signature of a successfully formed metal-molecule-metal junction after electrochemical deposition of a tran- sition metal layer. Chapter 5 then addresses the use of surface-enhanced Raman spectroscopy to identify charge transfer states of 4-mercaptopyridine by changing bias potential and excitation wavelength. A charge transfer state is found for protonated 4-mercaptopyridine at about 1.7 eV above the Fermi level, while the corresponding state for unprotonated 4-mercaptopyridine must lie at least 0.8 eV higher. Chapter 6 then explores the use of ultrafast vibrational sum frequency generation. The pyridine ring stretching modes are detected and metallisation of the 4-mercaptopyridine layer is seen to decrease the local order of the molecular layer. The influence of the mercaptopyridine charge transfer state can be seen in ultrafast pump - sum frequency probe spectroscopy of the gold substrate. This opens the prospect of investigating coupling between molecular vibrations and charge transfer in these junctions on a timescale of a picosecond or less.
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Fryling, Mark Aaron. "Raman Spectroscopy of Carbon Electrode surfaces /." The Ohio State University, 1994. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487859313346783.
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Wang, Peng. "Micro-Raman spectroscopy of GaAs nanowires." Paris 6, 2012. http://www.theses.fr/2012PA066482.
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Cette thèse présente une étude de micro spectroscopie Raman d’un type nouveau de nanostructures : les nanofils de semiconducteurs. Elle porte sur des nanofils de GaAs, d’un diamètre compris entre 50 et 150 nm, fabriqués par épitaxie par jets moléculaires. Il s’agit de la première étude systématique des modes de vibration et des résonances électroniques associées dans les deux formes cristallines qui peuvent être obtenues suivant les conditions de croissance : la blende de zinc comme pour GaAs massif et la WZ qui n’existe pas à l’état massif. La spectroscopie est réalisée sur un nanofil unique grâce à un dispositif de micro-Raman original développé pendant la thèse. Après une caractérisation d’ensemble des vibrations optiques, le travail s’est concentré sur deux volets particuliers : 1) l’étude des polarisations Raman des raies observées. Il a été mis en évidence que la symétrie microscopique des matériaux a une influence faible sur les polarisations observées qui sont entièrement dominées par l’anisotropie de forme des nanofils. Un modèle de confinement diélectrique a été développé qui reproduit bien l’essentiel des observations expérimentales et prédit une influence très forte du diamètre des fils qui a fait l’objet de vérifications préliminaires. 2) l’étude des résonances Raman. Il a d’abord été observé que la micro spectroscopie Raman standard avec une illumination par un laser à Argon ionisé à des longueurs d’onde vers 500nm est très difficile et conduit généralement à la destruction des fils étudiés à cause de la forte absorption optique dans cette gamme de longueurs d’onde. Il a été démontré qu’au contraire l’utilisation de longueurs d’onde dans la gamme 700-900nm est très bien adaptée et permet une étude complète et non destructive des nanofils de GaAs. Une observation très originale a été réalisée, une résonance de Fröhlich du phonon LO qui traduit une transition excitonique très fortement décalée en énergie dans les fils de forme WZ par rapport aux fils de forme blende de zinc où les observations sont conformes à ce qui est connu pour GaAs massif. Cette observation originale est en bon accord avec les prédictions de calculs ab initio de la structure de bande électronique de GaAs WZ et permet de préciser l’ordre et la symétrie des états de conduction qui fait l’objet de débats entre plusieurs variantes des calculs ab initio publiésThis thesis presents a study by micro-Raman spectroscopy of a new type of nanostructures: semiconductor nanowires. It is focused onto GaAs nanowires with diameter between 50 and 150nm, fabricated by Molecular beam epitaxy (MBE). This is the first systematic study of vibrations and related electronic resonances in the two crystalline forms available for GaAs nanowires depending of the growth conditions: zinc-blende (ZB) as in bulk GaAs and wurtzite (WZ), a form not stable in bulk form. Raman spectroscopy is performed on single nanowires thanks to a dedicated micro-Raman set-up developed during this work. Based on an overall characterization of optical vibrations, this work has been mainly focused on two research lines. 1) the study of Raman polarizations of the recorded lines. It has been evidenced that the microscopic symmetry of nanowires has a limited influence onto the observed polarizations which appear to be mostly controlled by the shape anisotropy of nanowires. A model of dielectric confinement has been developed and well reproduces most of the experimental observations. It predicts a significant dependence onto the diameter which has been confirmed by preliminary experiments on wires with different diameters. 2) the study of Raman resonances. It has been first observed that Raman micro spectroscopy in standard conditions, based on an Argon ion laser with wavelengths around 500nm, is very difficult and generally leads to the destruction of the wires because of strong light absorption of GaAs nanowires in this range of wavelengths. It has been demonstrated that on the contrary the use of wavelengths in the range 700-900nm is very well adapted and allows a full detailed, non destructive study of vibrations in GaAs nanowires. A novel original observation has been obtained in this energy range, the Fröhlich resonance of the LO phonon reflecting an excitonic transition in WZ nanowires shifted by around 100meV from the well established resonance in ZB GaAs. This novel observation well agrees with recent ab initio calculations of WZ GaAs electronic band structure and allows to establish the ordering and the symmetry of the lowest energy conduction states which remains controversial among different versions of published ab initio calculations
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Haydock, Richard. "Multivariate analysis of Raman spectroscopy data." Thesis, University of Nottingham, 2015. http://eprints.nottingham.ac.uk/30697/.
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This thesis is concerned with developing techniques for analysing Raman spectroscopic images. A Raman spectroscopic image differs from a standard image as in place of red, green and blue quantities for each pixel a Raman image contains a spectrum of light intensities at each pixel. These spectra are used to identify the chemical components from which the image subject, for example a tablet, is comprised. The study of these types of images is known as chemometrics, with the majority of chemometric methods based on multivariate statistical and image analysis techniques. The work in this thesis has two main foci. The first of these is on the spectral decomposition of a Raman image, the purpose of which is to identify the component chemicals and their concentrations. The standard method for this is to fit a bilinear model to the image where both parts of the model, representing components and concentrations, must be estimated. As the standard bilinear model is nonidentifiable in its solutions we investigate the range of possible solutions in the solution space with a random walk. We also derive an improved model for spectral decomposition, combining cluster analysis techniques and the standard bilinear model. For this purpose we apply the expectation maximisation algorithm on a Gaussian mixture model with bilinear means, to represent our spectra and concentrations. This reduces noise in the estimated chemical components by separating the Raman image subject from the background. The second focus of this thesis is on the analysis of our spectral decomposition results. For testing the chemical components for uniform mixing we derive test statistics for identifying patterns in the image based on Minkowski measures, grey level co-occurence matrices and neighbouring pixel correlations. However with a non-identifiable model any hypothesis tests performed on the solutions will be specific to only that solution. Therefore to obtain conclusions for a range of solutions we combined our test statistics with our random walk. We also investigate the analysis of a time series of Raman images as the subject dissolved. Using models comprised of Gaussian cumulative distribution functions we are able to estimate the changes in concentration levels of dissolving tablets between the scan times. The results of which allowed us to describe the dissolution process in terms of the quantities of component chemicals.
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Keen, Imelda P. "Forensic applications of Raman microprobe spectroscopy." Thesis, Queensland University of Technology, 1998.
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Guo, Yu. "RAMAN SPECTROSCOPY OF GLASSESWITH HIGH AND BROAD RAMAN GAIN IN THE BOSON PEAK REGION." Doctoral diss., University of Central Florida, 2006. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/4275.
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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.Ph.D.
Department of Physics
Sciences
Physics
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Bauer, Michael. "Raman spectroscopy of laser induced material alterations." Diss., lmu, 2010. http://nbn-resolving.de/urn:nbn:de:bvb:19-117196.
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Maltt, N. D. "Diagnosis of lung cancer by raman spectroscopy." Thesis, Queen's University Belfast, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.492488.
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lung cancer patients from 'at risk' controls and 'at risk' control subjects from healthy control subjects. Porphyrin-containing substances were higher in the 'at risk' controls than either the healthy controls or the lung cancer patients. Additionally the induced sputum from the three groups was analysed using Surface-enhanced Desorption-Ionization Time-of-flight mass spectrometry which also distinguished the three groups. A mini fibre optic probe was used in conjunction with shifted subtracted Raman spectroscopy to analyse normal and malignant ex vivo lung tissue from 7 patients, obtained from lung cancer surgical resections and could classify the two types of tissue perfectly. In conclusion, Raman spectroscopy has the potential to diagnose lung cancer, predict prognosis and elucidate the chemical changes associated with carcinogenesis.
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Atkins, Chad Garry. "Raman spectroscopy of transfusable red blood cells." Thesis, University of British Columbia, 2016. http://hdl.handle.net/2429/59728.
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Blood banking is an essential aspect of modern healthcare. When red blood cells (RBCs) are stored, they degrade over time as a result of various chemical and biological processes leading to an accumulation of waste products and oxidative damage, among others. Significant growth in the application of Raman spectroscopy (RS) to biomedical problems has made it a feasible tool for investigating biochemical changes associated with storage of RBCs. It was hypothesized that RS could be used to monitor in situ, non-destructively and non-invasively, certain structural and compositional changes associated with these ageing effects as they occur in storage bags. The presence of a relationship between these changes and the viability of RBCs would have substantial implications for the health care industry.
Preliminary results demonstrated the oxygenation state of hemoglobin in stored RBCs changed in a manner that was donor-dependent and that closely tracked the morphological index, a qualitative metric for evaluating cell quality. Investigations of the storage-solution supernatant revealed that lactate, a metabolic waste product, accumulated at different rates in stored bags and displayed more rapid accumulation in units from male donors than units from female donors.
It was shown that spatially offset Raman spectroscopy (SORS) could measure stored RBC biochemistry through the plastic bag. Spectra collected with SORS compared well with previously-obtained conventional Raman spectra. Thus, information about the contents of a stored unit could be obtained without breaching its sterility. These outcomes provided proof-of-concept for the development of a SORS-based instrument to measure storage bag contents in a rapid and non-invasive manner.
The results reported in this thesis fall into two distinct categories. Regarding the observed data, the substantial inter-donor variability and gender and age effects have significant implications for the design of clinical trials, the collection and administration of donated blood, and clinical use. Regarding instrumentation, obtaining chemical information from stored RBCs using RS will enable new research directions for the field of transfusion medicine and obtaining this information in situ from storage bags will have utility for quality control in a blood bank or hospital setting.Science, Faculty of
Graduate
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Brocke, Thomas. "Electronic Raman spectroscopy on semiconductor quantum dots." Göttingen Cuvillier, 2007.
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Koljenovic, Senada. "Towards clinico-pathological application of Raman spectroscopy." [S.l.] : Rotterdam : [The Author] ; Erasmus University [Host], 2008. http://hdl.handle.net/1765/11739.
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Tatham, Martin Christopher. "Time resolved Raman spectroscopy of semiconductor structures." Thesis, University of Oxford, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.305429.
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Agaiby, Rouzet Michael Behnam. "Nanometer Scale Strain Characterisation Using Raman Spectroscopy." Thesis, University of Newcastle Upon Tyne, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.506504.
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Barrett, L. J. "Raman spectroscopy of illicit drugs and pharmaceuticals." Thesis, Queen's University Belfast, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.269165.
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Bennett, Robert. "New development in Fourier transform Raman spectroscopy." Thesis, University of Southampton, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.242461.
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CRUZ, JOSE FLAVIO MARTINS. "CARACTEREZITION OF GASOLINES BY FT-RAMAN SPECTROSCOPY." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2003. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=4333@1.
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PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIROVisando determinar os teores dos componentes relevantes e as propriedades físicas de gasolinas comerciais e sintéticas foram tomados espectros Raman de 60 gasolinas comerciais e 52 misturas sintéticas simulando gasolinas. Os espectros foram tomados em um espectrômetro Nicolet FT Raman 950. Os espectros brutos obtidos foram tratados para evitar a influência da variabilidade de potência do laser excitante sobre as intensidades das linhas Raman. As variáveis independentes (intensidades Raman ) e as variáveis dependentes (propriedades das gasolinas comerciais e misturas sintéticas ) foram centradas em torno da média e submetidas à regressão por mínimos quadrados parciais, visando ajustar modelos que permitissem predizer quantitativamente os teores de etanol, hidrocarbonetos saturados, insaturados e aromáticos além dos valores das propriedades MON, RON, densidade e pontos de ebulição inicial, final, a 10%, 50% e 90% das amostras em estudo. Os resultados obtidos mostraram a potencialidade da espectroscopia Raman, para o desenvolvimento de métodos confiáveis para a análise de diversas características das gasolinas estudadas.
The aim of this work was to determine the contents of the more important components and physical properties of commercial gasolines and synthetic mixtures with known composition, prepared in the laboratory. The Raman spectra of 60 gasolines and 52 mixtures were acquired with a Nicolet 950 Fourier Transform Raman (FT-Raman) spectrometer. The raw spectra were treated to avoid the laser potency variability on Raman lines intensities. The independent variables (Raman intensities) and the dependent variables (gasolines and mixtures properties) were mean centered and models were fit by partial least square regression seeking to predict the contents of ethanol, saturated, unsaturated and aromatic hydrocarbons. Also properties as MON, RON, density and boiling point values were determined by this procedure. The final results showed the potential of Raman spectroscopy for analysis of several properties of gasolines.
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Zelai, Taharh. "Nanoscale Raman spectroscopy of graphene nanodevice structures." Thesis, University of Southampton, 2017. https://eprints.soton.ac.uk/419483/.
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Graphene is an atomically-thin 2-dimentional layer of carbon atoms. Since 2004, it has been attracting significant attention for various type of device applications due to its unique properties. In particular, applications of graphene for micro- and nanoscale devices is one of the most demanded and promising research fields. For further advancement of technological flexibility in designing graphene nanodevices, introducing defects to graphene could be a useful method to modify its material properties. Therefore, how to control defects in graphene and how to observe the effects of defects are one of the most important issues. For instance, the defect formed on graphene has been observed to make influence on the charge carrier concentration. Moreover, the defect introduction to graphene will change the phase of the graphene from crystalline to amorphous. Tip-enhanced Raman Spectroscopy (TERS) is a combination of Scanning Probe Microscopy (SPM) and micro-Raman spectroscopy. While micro Raman has played a crucial role to characterise graphene material properties at a microscale level, TERS is considered to be a powerful tool to investigate and characterise nanostructure devices, defect density, and doping with high spatial resolution down to sub 100 nm. In this work my aim is to establish TERS measurement techniques for various types of graphene. Then the TERS is applied for evaluating defect density, edge properties and strain induced in the graphene nanoelectronic and nanoelectromechanical devices to investigate the physics of graphene nanodevices. I have started to optimise the TERS tools on graphene to achieve high spatial resolution. Then I have applied TERS for studying the stress and strain and defect formation on suspended graphene on SiNWs. The result shows that the peak position is shifted in the TERS spectra and additionally the local defects at the edge of SiNW have been observed with a spatial resolution of ~ 100 nm. Then I have introduced defects using helium ion irradiation on graphene nanoribbon (GNR). TERS is used to study the graphene edges and irradiation boundary of in the graphene channels. I have succeeded in taking TERS spectra across the edge of the He-ion-irradiated region on graphene for the first time and confirmed that higher spatial resolution is achievable with TERS.
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Oh, Jeankun 1968. "Transcutaneous measurement of glucose using Raman spectroscopy." Thesis, Massachusetts Institute of Technology, 2004. http://hdl.handle.net/1721.1/27121.
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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2004.Includes bibliographical references (p. 86-88).
Transcutaneous glucose measurement would provide the ability to obtain frequent measurements without the pain and risk of infection associated with obtaining a blood sample and eliminates the need for reagents. Because of these potential benefits, a large effort is being made within the academic and industrial research communities to develop alternative rapid and easily manageable analysis methods, including transcutaneous methods. Several optical techniques have been proposed and investigated widely to replace the traditional method. Transcutaneous measurement would be of particular benefit to the millions of people with diabetes who should monitor glucose levels multiple times per day and today depend on the finger pricking devices. We have used the advantages provided by NIR Raman spectroscopy, i.e. sharp and distinct spectral features combined with a large probe volume, in order to simultaneously quantify multiple analytes (glucose, urea, cholesterol, triglycerides, total protein, albumin, hemoglobin, hematocrit (hct)) in serum and whole blood samples. Based on the successful measurements, we have moved toward transcutaneous measurements of glucose from 16 healthy human subjects as the first target of blood analytes. RMSEP of 13.17 mg/dL and r² values of 0.79 show promise that the Raman spectroscopy can be developed to achieve clinical accuracy requirements. Furthermore, the fact that glucose features could be recognized in the calibration spectra from measurements of volunteers whose glucose levels changed in a relatively large range, provides evidence that the calibration is based upon glucose.
by Jeankun Oh.
S.M.
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Son, HyungBin 1981. "Raman spectroscopy of single wall carbon nanotubes." Thesis, Massachusetts Institute of Technology, 2008. http://hdl.handle.net/1721.1/44725.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2008.Includes bibliographical references (p. 71-76).
A single wall carbon nanotube (SWNT) is a new form of carbon, whose atomic arrangement is equivalent to a graphene sheet rolled into a cylinder in a seamless way. The typical diameter of a SWNT ranges from 0.6 nm to several nm and the typical length ranges from tens of nm to several cm. Due to its small diameter and high aspect ratio, a SWNT has very unique electronic and vibrational properties. The goals of this thesis work are to design and construct a Raman instrument capable of obtaining signals from many different types of individual SWNTs, to develop methods and tools to collect, organize and analyze large amounts of Raman spectra from them, to use resonant Raman spectroscopy to characterize individual SWNTs, and to investigate how their electronic and vibrational properties change under various conditions, such as strain, or different substrate interactions. A high-efficiency widely-tunable Raman instrument is developed for the study of SWNTs. The environmental effects on the electronic and vibrational properties are investigated by suspended SWNTs. Using the high-efficiency Raman instrument, weak optical transitions of metallic SWNTs are found. The effect of strain on the vibrational mode frequencies of SWNTs are studied.
by Hyungbin Son.
Ph.D.
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Bhatia, Pankaj 1974. "Using Raman spectroscopy to study supercritical CO₂." Thesis, Massachusetts Institute of Technology, 1999. http://hdl.handle.net/1721.1/85310.
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Lloyd, Jonathan S. "The development of tip enhanced raman spectroscopy." Thesis, Swansea University, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.678427.
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Touzalin, Thomas. "Tip-enhanced Raman spectroscopy on electrochemical systems." Thesis, Sorbonne université, 2018. http://www.theses.fr/2018SORUS364.
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L'analyse in situ d'interfaces électrochimiques à l'échelle nanométriques est un enjeu majeur pour la compréhension des mécanismes de transferts de charges et d'électrons dans les domaines du stockage d'énergie ou de l'électrocatalyse. Ce travail a permis le développement de la spectroscopie Raman exaltée de pointe (TERS) en milieu liquide et en conditions électrochimiques. Le TERS permet l'analyse de la structure de molécules ou de matériaux à l'échelle nanométrique du fait de l'exaltation localisée du champ électrique à l'extrémité d'une sonde de microscope à effet tunnel (STM) en or ou en argent. Un dispositif reposant sur l'illumination d'une pointe au travers d'un solvant organique a démontré la possibilité d'imager les inhomogénéités d'une monocouche auto-assemblée sur or. Une seconde approche reposant sur l'exaltation du signal Raman à l'apex d'une pointe de taille nanométrique utilisée comme microélectrode (spectroscopie Raman exaltée de surface de pointe, tip SERS) a permis de suivre la réduction d'une monocouche auto-assemblée et d'améliorer la compréhension de son mécanisme. Afin d'imager la surface d'une électrode polarisée, le couplage d'un STM utilisant une pointe TERS en conditions électrochimiques a montré une résolution latérale de moins de 8 nm pour sonder de variations locales de l'exaltation du champ électromagnétique induites par des singularités géométriques de surface. Par ailleurs, l'analyse TERS de couches organiques formées à partir de sels d'aryldiazoniums a permis de montrer des différences de structures selon type de greffage. Ce travail constitue donc une avancée majeure pour l'analyse locale de surfaces modifiéesThe in situ investigation of electrochemical interfaces structures at the nanoscale is a key element in the understanding of charge and electron transfer mechanisms e.g. in the fields of energy storage or electrocatalysis. This thesis introduces the implementation of tip-enhanced Raman spectroscopy (TERS) in liquid and in electrochemical conditions enabling the nanoscale analysis of electrified solid/liquid interfaces through the strong and local electric field enhancement at gold or silver scanning tunneling microscopy (STM) probes. The ability of TERS to image inhomogeneities in the coverage density of a self-assembled monolayer (SAM) through a layer of organic solvent on gold was demonstrated. A TERS-inspired analytical tool was also developed, based on a TERS tip used simultaneously as a single-hot spot surface-enhanced Raman spectroscopy (SERS) platform and as a microelectrode (EC tip SERS). The reduction of an electroactive SAM could then be monitored by electrochemical and in situ SERS measurements. In situ electrochemical STM-TERS was also evidenced through the imaging of local variations of the electric field enhancement on peculiar sites of a gold electrode with a lateral resolution lower than 8 nm. Finally TERS also demonstrated to be efficient in investigating the structure of organic layers grafted either by electrochemical reduction or spontaneously. This work is therefore a major advance for the analysis of functionalized surfaces
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Viranna, Narendra Balaguru. "Coherent anti-Stokes Raman spectroscopy of diamond." Master's thesis, University of Cape Town, 1997. http://hdl.handle.net/11427/26229.
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Experiments were performed to investigate Coherent Anti-Stokes Raman Scattering (CARS) in diamond. Aspects of this type of non-linear scattering are presented theoretically, and various experimental configurations were attempted in order to study them. These included the dependence of the CARS signal intensity on the intensities of the two exciting frequency-doubled Nd:YAG (pump) and dye (Stokes) lasers, the variation of the CARS signal polarization as a function of the lasers' polarization, and the dependence of the CARS signal intensity on the phase mismatch of the laser beams. The phase mismatch measurement confirmed the predicted sinc² nature of the CARS signal intensity, while· the polarization measurements provided new information on the ratio of the non-vanishing components of the cubic susceptibility x³ of diamond. The CARS signal intensity was found to change linearly with the dye laser intensity and quadratically with the Nd: Y AG laser intensity. The CARS signal was found at the predicted 1332 cm⁻¹ shift from the doubled Nd:YAG emission, and its linewidth of 1.2 cm⁻¹ is in agreement with the spontaneous Raman linewidth.The spectral data were fitted to a modified Voigt profile containing the non-resonant cubic susceptibility contribution, and this allowed us to establish the ratio of the resonant and non-resonant parts of x³. An attempt to generate Stimulated Raman Scattering in diamond was unsuccessful.
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Claps, Ricardo Javier. "Novel developments in laser diode raman spectroscopy /." Digital version accessible at:, 2000. http://wwwlib.umi.com/cr/utexas/main.
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Scherzer, Ryan D. "Degradation Resistant Surface Enhanced Raman Spectroscopy Substrates." UNF Digital Commons, 2017. http://digitalcommons.unf.edu/etd/760.
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Raman spectroscopy is employed by NASA, and many others, to detect trace amounts of substances. Unfortunately, the Raman signal is generally too weak to detect when very small, but non-trivial, amounts of molecules are present. One way around this weak signal is to use surface enhanced Raman spectroscopy (SERS).
When used as substrates for SERS, metallic nanorods grown using physical vapor deposition (PVD) provide a large enhancement factor to the Raman signal, as much as 1012. However, Silver (Ag) nanorods that give high enhancement suffer from rapid degradation as a function of time and exposure to harsh environment. Exposure to harsh environments is an enormous issue for NASA; considering all environments experienced during space missions will be drastically different from Earth regarding atmosphere pressure, atmosphere composition, and environmental temperature. Au and Ag nanorods suffer from a thermochemical kinetic phenomenon where the surface atoms diffuse and cause the nanostructures to coalesce towards bulk structure. When in bulk, SERS enhancement is lost and the substrate becomes useless.
A stable structure for SERS detection is designed through engineering the barriers to surface diffusion. Aluminum (Al) nanorods are forced to undergo surface diffusion through thermal annealing and form rough mounds with a stable terminating oxide layer. When Ag is deposited on top of this Al structure, it becomes kinetically bound and changes to physical structure become impeded. Using this paradigm, samples are grown with varied lengths of Ag and are then characterized using scanning electron microscopy (SEM) and Ultraviolet-Visible spectroscopy. The performance of the samples are then tested using SERS experiments for the detection of trace amounts of rhodamine 6G, a ‘gold standard’ analyte. Characterization shows the effectiveness of the Raman substrates remains stable up to 500°C.
Transitioning to basic scientific investigation, next is to strive to isolate the individual impacts of chemical and physical changes to the Ag nanostructure and how they affect the Raman signal. Substrates are compared over the course of a month long experiment to determine the effects of vacuum storage and addressing the effects of chemical adsorbance. Additionally, this was attempted by comparing the signal degradation of Ag nanorods to that of Au, which is known to be chemically inert, allowing for the separation of chemical and physical effects. Although Ag and Au have similar melting points, Ag physically coarsened significantly more. FTIR also showed significant chemical contamination of the Ag, but not Au. A hypothesis is proposed for future investigations into the chemical changes and how they are coupled with and promote the physical changes in nanostructures.
Overall, the novel SERS substrate engineered here may enable the detection of trace amounts of molecules in harsh environments and over long timescales. Conditions such as those found on space missions, where substrates will experience months or years of travel, high vacuum environments, and environments of extreme temperatures.
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Dyer, Christopher David. "Chemical applications of Fourier-transform Raman spectroscopy." Thesis, University of Southampton, 1995. https://eprints.soton.ac.uk/424218/.
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Details are presented of five studies in the application of Fourier transform (FT) Raman spectroscopy. The studies encompass a diverse range of chemical species, and indicate the wide applicability of FT-Raman methods. A series of coloured sulphur-containing organic compounds based on the thione ring structure were analysed. Characteristic group frequencies were determined, enabling the thione ring structure to be easily identified. Spectral changes on reaction of thiones or related oxones to yield tetrathiafulvalenes (TTFs) were discovered, whilst the differentiation of thione and oxone species was shown to be straightforward. The novel allenylketenimine-tetracyanoethylene (TCNE) system was investigated, in order to provide the first vibrational assignment of these compounds. Characteristic frequencies of the underlying cyclic structure were determined. The extremely weak IR absorption of the nitrile (-CN) group was noted, contrasted against the reliable Raman signature, and discussed. The first study of the hydrated y-alumina surface was undertaken in a combined FTIR/FT-Raman study, that unambiguously determined the surface to comprise the bayeritic polymorph of aluminium hydroxide. The temperature and pH-dependency of the formation of the hydroxide were studied. The role of phenylphosphate in the suppression of hydration was discussed. Near-IR excitation was shown to produce anomalous luminescence from a series of calcium silicate cement minerals. Investigations using near-IR diffuse reflectance suggested a connection with the presence of metal ions impurities (especially manganese) and calcium hydroxide. Calcium oxide and hydroxide were shown to display similar anomalous behaviour. The application of conventional Raman spectroscopy in this area was appraised as an alternative, and shown to be successful. A method for obtaining rotational and vibrational spectra of gases on a commercial FT-Raman spectrometer using multiple-reflection cells was designed, developed, and appraised. The technique was then applied to a previously-intractable system (NO2/N2O4) to record the first vapour-phase spectrum of the dimer. In addition, the data suggests that the NO minority species scattering may be strongly-enhanced, and that NO? may be unenhanced at this wavelength.
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Vega, Marienette Morales. "RAMAN AND FLUORESCENCE SPECTROSCOPY OF BIOMEDICAL NANOMATERIALS." Doctoral thesis, Università degli studi di Trieste, 2015. http://hdl.handle.net/10077/10900.
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2013/2014Stabilized zirconia exhibits unsurpassed mechanical properties and biocompatibility, making it an indispensable ceramic material for biomedical implants. One of the most problematic features of stabilized zirconia has been its low-temperature degradation(LTD), which is associated to the observed transformation of its crystalline structure from tetragonal to monoclinic phase. The presence of monoclinic phases, therefore, is the red-flag for the impending catastrophic breakdown of mechanical properties. In this work, we establish characterization protocols to extend the sensitivity limit of conventional Raman spectroscopy for determination of extremely little amounts of monoclinic phase in zirconia implant prototypes. We accomplish this in two ways. First, we employ Raman spectroscopy and multivariate statistical analysis on a series of fully-dense and partially transformed Y-TZP zironia prototypes. Incipient t-m transformation is only revealed with high resolution spectral mapping and principal component analysis. The technique reveals the presence of islands of monoclinic phase that are otherwise not visible by simple observation and fitting of individual spectra. High resolution mapping likewise allows for probing homogenieties in the sample, which is a critical component in the development of implants. The second protocol utilizes surface-enhanced Raman spectroscopy (SERS) with colloidal gold nanostars as substrate. The nanostars used have localized surface plasmon resonance (LSPR) at 690 nm. Two spectral maps, on clean and on nanostars-covered surface, were obtained exactly at the same position using confocal Raman spectroscopy. Comparison of the two maps shows that there are more monoclinic phases detected in the nanostars-covered surface possibly due to the “lightning rod” effect in the nanostar tips. We report an unprecedented attempt on SERS on solid zirconia, which provides early evidence of the effectivity of the technique even on non-porous materials. With further improvement in sensitivity, SERS is a promising technique for the early detection of monoclinic phase in zirconia-based implants.
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SACCO, ALESSIO. "Metrological Approach to Tip-enhanced Raman Spectroscopy." Doctoral thesis, Politecnico di Torino, 2020. http://hdl.handle.net/11583/2827709.
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Beaman, R. A. "Two beam coherent spectroscopy." Thesis, Cardiff University, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.379609.
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Liu, Xiaohua. "Resonance raman studies of hemoproteins." Thesis, Georgia Institute of Technology, 1989. http://hdl.handle.net/1853/27170.
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