DANTAS, Saulo Maia. Microscopia de campo próximo aplicada ao estudo dos domínios ferroelásticos. 2011. 116 f. Dissertação (Mestrado em Física) - Programa de Pós-Graduação em Física, Departamento de Física, Centro de Ciências, Universidade Federal do Ceará, Fortaleza, 2011. / Submitted by Edvander Pires (edvanderpires@gmail.com) on 2015-10-16T20:43:18Z No. of bitstreams: 1 2011_dis_smdantas.pdf: 2227981 bytes, checksum: 19c007c3550b22fce922a346d6f4508f (MD5) / Approved for entry into archive by Edvander Pires(edvanderpires@gmail.com) on 2015-10-21T20:37:21Z (GMT) No. of bitstreams: 1 2011_dis_smdantas.pdf: 2227981 bytes, checksum: 19c007c3550b22fce922a346d6f4508f (MD5) / Made available in DSpace on 2015-10-21T20:37:21Z (GMT). No. of bitstreams: 1 2011_dis_smdantas.pdf: 2227981 bytes, checksum: 19c007c3550b22fce922a346d6f4508f (MD5) Previous issue date: 2011 / A significant part of the nowadays scientific research is based on the synthesis, characterization and application of the nanostructured materials. In order to make possible a further understanding of the intriguing properties of these materials, many techniques with nanometric and even subnanometric resolution have been created during the last 50 years and are passing through a process of continuous improvement. In spite of the great scientific and technical development on the available instrumentation, the optical characterization with nanometric resolution of these materials remains a challenge for researchers from all over the world. In this context, techniques based on near field radiation have emerged as a great alternative for the diffraction limit break which is a nature imposed limit for conventional optical instruments. Besides this, contact near field microscopy in illumination mode acquires optical and topographical information of the material simultaneously. This capability permits the distinction between the real and topographic induced nanometric optical features. The domain phenomenon in crystals has been a subject of interest for crystallographers since crystallography started to develop as a scientific branch. The obvious reasons are the beauty of some domain patterns as well as evident and challenging symmetry relations between their constituents. The ferroelastic domains are one of the important kinds of domains presented by crystals. They have, sometimes, very small dimensions without inducing any topographic element on the sample. On the other side the optical behavior of different domains under almost the same measurement condition may be very dissimilar. Such characteristics make then an ideal class of materials for contact near field microscopy in illumination mode based studies. Ferroelastic domains images, using near-field optical microscopy in illumination and contact mode, were obtained with a nanometric resolution. Such images, in general, presented very little relation with the topographical structure of the material, revealing optical and structural features such as occurrence of the waveguide effect in the domains, domain´s dimensions and presence of dislocations on the crystalline structure. / Uma parcela significativa da pesquisa científica hodierna baseia-se na síntese, caracterização ou aplicação de materiais nanoestruturados. No intuito de possibilitar um maior entendimento das intrigantes propriedades destes materiais, muitas técnicas com resolução nanométrica e até subnanométrica foram criadas nos últimos 50 anos e têm passado por um processo de contínuo aprimoramento. Apesar do grande desenvolvimento técnico e científico da instrumentação disponível, a caracterização ótica com resolução nanométrica destes materiais tem se mostrado um desafio para pesquisadores do mundo inteiro. Nesse contexto, as técnicas baseadas em radiação de campo próximo têm despontado como uma boa alternativa para quebra do limite de difração, que constitui um limite natural para os instrumentos óticos convencionais. Além disso, a microscopia de campo próximo em modo de iluminação e contato adquire simultaneamente informações óticas e topográficas do material, o que permite fazer uma distinção entre as propriedades óticas nanométricas reais e as induzidas por topografia. O fenômeno de domínios cristalográficos tem sido um assunto de interesse da cristalografia desde que ela começou a se desenvolver como ciência. As razões óbvias para isso são a beleza de formas externas de algumas estruturas de domínios, assim como as evidentes e desafiantes relações de simetria entre os seus constituintes. Os domínios ferroelásticos são um dos importantes tipos de domínios apresentados por cristais. Tais domínios apresentam, algumas vezes, dimensões muito reduzidas sem manifestar uma considerável alteração na estrutura topográfica da amostra. Por outro lado, o comportamento ótico de domínios distintos pode ser bem diferente quando sujeitos a uma mesma condição de medida. Tais características tornam esta classe de materiais ideais para um estudo baseado na microscopia de campo próximo em modo de iluminação e contato. Imagens de domínios ferroelásticos, utilizando microscopia de campo próximo em modo de iluminação e contato, foram obtidas com resolução nanométrica. Tais imagens, em geral, apresentaram pouquíssima relação com a estrutura topográfica do material, revelando importantes características óticas (ocorrência do efeito de guias de onda nos domínios) e estruturais (dimensões dos domínios ferroelásticos, presença de defeitos de deslocamento na rede cristalina).

ALENCAR, Rafael Silva. Propriedades vibracionais de nanotubos de carbono de parede tripla. 2012. 56 f. Dissertação (Mestrado em Física) - Programa de Pós-Graduação em Física, Departamento de Física, Centro de Ciências, Universidade Federal do Ceará, Fortaleza, 2012. / Submitted by Edvander Pires (edvanderpires@gmail.com) on 2015-10-20T18:07:10Z No. of bitstreams: 1 2012_dis_rsalencar.pdf: 14324978 bytes, checksum: c3141fb65daa6e09440a353e83cd0d08 (MD5) / Approved for entry into archive by Edvander Pires(edvanderpires@gmail.com) on 2015-10-20T21:04:27Z (GMT) No. of bitstreams: 1 2012_dis_rsalencar.pdf: 14324978 bytes, checksum: c3141fb65daa6e09440a353e83cd0d08 (MD5) / Made available in DSpace on 2015-10-20T21:04:27Z (GMT). No. of bitstreams: 1 2012_dis_rsalencar.pdf: 14324978 bytes, checksum: c3141fb65daa6e09440a353e83cd0d08 (MD5) Previous issue date: 2012 / The study of the electronic, mechanical and vibrational properties of the carbon nanotubes with few layers is important for developing and improving models that could describe the behavior of multi-walled carbon nanotubes (MWNTs), which is the kind of nanotube most used in technological applications. Several theoretical and experimental studies have been conducted for understanding the behavior of single and double walled carbon nanotubes (SWNT and DWNT, respectively) under high hydrostatic pressures. However, the behavior of triple walled carbon nanotubes (TWNTs) under such conditions is still unknown. Here, we present a study of resonance Raman spectroscopy in TWNTs as function of hydrostatic pressure. We used paraffin oil and a mixture of methanol:ethanol in 4:1 ratio as pressure transmitting media (PTM) and a diamond anvil cell (DAC) for applying pressure. The evolution of the radial breathing modes (RBM) and the tangential modes (G band) as a function of pressure was analyzed in detail and compared with existing results for SWNTs and DWNTs. The Raman spectroscopy data show that the shielding effects of inner tubes in TWNTs are more pronounced than in DWNTs. The changes in the intensities of Raman modes were interpreted as being associated with pressure induced changes in the resonance conditions. / O estudo das propriedades eletrônicas, mecânicas e vibracionais dos nanotubos de carbono com poucas camadas é importante para desenvolver e aprimorar os modelos que descrevem o comportamento dos nanotubos de parede múltipla, que é o tipo de nanotubo mais usado em aplicações tecnológicas. Diversos estudos teóricos e experimentais têm sido realizados visando o entendimento do comportamento dos nanotubos de carbono de paredes simples e dupla (SWNT e DWNT, respectivamente) submetidos a altas pressões hidrostáticas. Entretanto, o comportamento de nanotubos de carbono de parede tripla (TWNTs) sob tais condições é ainda desconhecido. Neste trabalho, apresentamos um estudo de espectroscopia Raman ressonante em TWNTs em função da pressão hidrostática. Utilizamos óleo de parafina (Nujol) e uma mistura de metanol:etanol na proporção de 4:1 como meios transmissores de pressão (PTM) e uma célula de pressão de bigorna de diamante (DAC-Diamond Anvil Cell) para a aplicação da pressão. A evolução dos modos radiais (RBM) e tangenciais (Banda G) em função da pressão foi analisada de forma detalhada e comparada com os resultados existentes para os nanotubos de parede simples e dupla. Os dados de espectroscopia Raman mostram que os efeitos de blindagem internos dos TWNTs são mais acentuados que nos DWNTs. As modificações nas intensidades dos modos Raman foram interpretadas como sendo associadas as mudanças nas condições de ressonância dos modos RBM em função da pressão.

ALMEIDA, Rodrigo Queirós de. Microscopia de Varredura por Sonda em Materiais Carbonosos. 2013. 70 f. Dissertação (Mestrado em Física) - Programa de Pós-Graduação em Física, Departamento de Física, Centro de Ciências, Universidade Federal do Ceará, Fortaleza, 2013. / Submitted by Edvander Pires (edvanderpires@gmail.com) on 2015-10-22T19:16:53Z No. of bitstreams: 1 2013_dis_rqalmeida.pdf: 4257729 bytes, checksum: 8993dc0445c4b4fc64370420016a9606 (MD5) / Approved for entry into archive by Edvander Pires(edvanderpires@gmail.com) on 2015-10-22T19:25:30Z (GMT) No. of bitstreams: 1 2013_dis_rqalmeida.pdf: 4257729 bytes, checksum: 8993dc0445c4b4fc64370420016a9606 (MD5) / Made available in DSpace on 2015-10-22T19:25:30Z (GMT). No. of bitstreams: 1 2013_dis_rqalmeida.pdf: 4257729 bytes, checksum: 8993dc0445c4b4fc64370420016a9606 (MD5) Previous issue date: 2013 / Graphene is dened as one-dimensional crystal structure, formed by a hexagonal network of carbon atoms,and due to the in unique structural and electronic properties, there is a great interest in investigating the physical properties of materials obtained from the chemical modi cation of graphene. Furthermore, graphene is the basic structural framework for all allotropes of carbon structure graphitic (hybridization sp2) and may be curled in a spherical shape, forming fullerenes (0D), rolled up into a cylindrical structure known as carbon nanotubes (1D), stacked, thus generating graphite (3D) and cut into stripes thus forming graphene nanoribbons. Among these materials derived from graphene, those that are synthesized from the oxidation of the graphene sheet, called graphene oxide (GO) are set apart. This work was focused to sample preparation of carbon nanostructures and their caracterization by means of Scanning Probe Microscopies (SPM) aiming to get a better understanding of the morphology and physical properties of these materials. In particular, the goal of this study was to investigate the morphological characteristics of CNTs and the electrostatic properties of graphene using SPM techniques. For this, we analyzed the mechanical behavior of carbon nanotubes when subjected to a radial compression by using AFM tip and the results were compared with those reported in the literature. Regardig the graphene we measured by AFM (Atomic Force Microscopy), EFM (Electric Force Microscopy) and Raman spectroscopy in pristine graphene, graphene treated with nitric oxide and graphene oxide, and the results were discussed and compared to each other. The graphene samples were obtained by using the exfoliation method of graphite and mechanical measurements performed in ambient atmosphere. The results showed that treatment with nitric acid resulted in peak shift of G band in graphene and also caused a change in the electrostatic behavior of edges of the sample when compared to pristine graphene. / O grafeno é definido como uma estrutura cristalina bidimensional, formada por uma rede hexagonal de átomos de carbono, e devido às suas propriedades eletrônicas e estruturais, existe um enorme interesse em investigar as propriedades físicas de materiais originados da modificação química do grafeno. Além disso, o grafeno é a base para todos os alótropos de carbono com estrutura grafítica (hibridização sp2), podendo ser envolvido de forma esférica, formando os fulerenos (0D), enrolado em uma estrutura cilíndrica conhecida como nanotubos de carbono (1D), ou empilhado, gerando assim, o grafite (3D), ou cortado em fitas gerando os "ribbons" (1D). Dentre esses materiais derivados do grafeno, destacam-se os que são sintetizados a partir da oxidação da folha de grafeno, chamados de óxido de grafeno (OG). Esse trabalho foi direcionado à preparação de amostras de nanoestruturas de carbono e a realização de medidas de Microscopia de Varredura por Sonda (SPM), tendo como finalidade, uma melhor compreensão da morfologia e das propriedades físicas desses materiais. Em específico, o escopo desse trabalho foi estudar as características morfológicas de Nanotubos de carbono e as propriedades eletrostáticas do grafeno com o uso das técnicas de SPM. Para isso, analisou-se o comportamento mecânico de Nanotubos de carbono quando sujeitos a compressões radiais usando uma ponta de AFM e os resultados foram, então, comparados com resultados conhecidos na literatura. No que diz respeito ao grafeno, foram realizadas medidas de AFM (Microscopia de Força Atômica), EFM (Microscopia de Força Elétrica) e Espectroscopia Raman em amostras de grafeno puro, grafeno tratado com ácido nítrico e óxido de grafeno. Os resultados foram, então, discutidos e comparados entre si. As amostras de grafeno foram obtidas a partir do método de esfoliação mecânica do grafite e as medidas realizadas em atmosfera ambiente. Dessa forma, os resultados mostraram que o tratamento com ácido nítrico, resultou no desvio no pico da banda G no grafeno e, também, ocasionou uma mudança no comportamento eletrostático nas bordas da amostra, quando comparado ao grafeno puro.

O presente trabalho estuda a produção e modificações físico-químicas do grafeno frente a tratamentos térmicos. Em uma primeira etapa, foi investigada a síntese de grafeno pela técnica de Deposição Química a partir da fase Vapor (CVD) sobre fitas de cobre. Nós variamos quatro parâmetros que influenciam no crescimento de grafeno: fluxo de metano (CH4), fluxo de hidrogênio (H2), tempo de crescimento e grau de pureza do cobre. Usando as técnicas de caracterização de espectroscopia Raman e microscopia óptica, observamos que fluxo menor de H2 e fluxo intermediários de CH4 favorecem o crescimento de grafeno de alta qualidade. Além disso, vimos que 15 minutos de crescimento de grafeno é suficiente para cobertura do substrato de cobre com grafeno. Por fim, foi visto que o maior grau de pureza do cobre permite a produção de monocamadas de grafeno mais homogêneas. Numa segunda etapa, foi realizado um estudo com objetivo de entender a interação de hidrogênio com monocamadas de grafeno. Nós usamos amostras de grafeno depositadas em filmes de SiO2 (285 nm)/Si e tratadas termicamente em atmosfera controlada de deutério (99,8%) em temperaturas entre 200 e 800 °C. Nós também investigamos a dessorção de hidrogênio do grafeno usando amostras previamente tratadas em deutério a 600 °C e depois tratadas em atmosfera controlada de nitrogênio em temperaturas entre 200 e 800 °C. Após os tratamentos, análise por reação nuclear (NRA) foi realizada para quantificar o deutério, onde nós observamos uma grande incorporação de deutério no grafeno acima de 400 °C, tendo um aumento moderado até 800 °C. Nós também observamos que a dessorção do deutério do grafeno ocorre apenas em 800 °C, embora a dessorção de deutério do óxido de silício ocorra a partir de 600°C. Espectroscopia Raman também foi realizada após cada tratamento térmico. Os resultados mostram que os defeitos na estrutura do grafeno têm um grande aumento para as etapas de maior temperatura na incorporação de deutério. Análises realizadas com Espectroscopia de Fotoelétrons Induzidos por Raios X (XPS) mostraram que a incorporação de deutério para maiores temperaturas causa o "etching" do grafeno. Por fim, caracterizações usando Espectroscopia de Absorção de Raios X (NEXAFS) mostraram que o deutério liga-se ao grafeno sem orientação preferencial. / The present work studies the production and physical-chemical modifications of the graphene under thermal annealings. In a first study, the graphene synthesis by Chemical Vapor Deposition (CVD) on copper foils was investigated. We varied four parameters that influence the growth of graphene: methane flow (CH4), hydrogen flow (H2), growth time and copper purity. Using Raman spectroscopy and optical microscopy, we observed that lower flux of H2 and intermediate flux of CH4 leads to the growth of high quality graphene. In addition, we observed that 15 minutes growth of graphene is sufficient to cover the copper substrate. A higher copper purity allows the production of homogeneous graphene monolayers. In a second step, a study was carried out to understand the interaction of hydrogen with graphene monolayers. We used graphene samples deposited on SiO2 (285 nm)/Si films and annealed in a controlled atmosphere of deuterium (99.8%) at temperatures between 200 and 800 °C. We also investigated the hydrogen desorption of graphene using samples previously treated in deuterium at 600 °C and then annealed in a controlled atmosphere of nitrogen at temperatures between 200 and 800 °C. After the annealings, nuclear reaction analysis (NRA) was performed to quantify the deuterium, where we observed a large incorporation of deuterium in graphene above 400 °C, with a moderate increase up to 800 °C. We also observed that desorption of deuterium occurs only at 800 °C, although deuterium desorption from silicon oxide occurs at 600 °C. Raman spectroscopy was also performed after each annealing. The results show that defects in the structure of graphene have a large increase for deuterium incorporation. Analyzes carried out with X-ray Photoelectron Spectroscopy (XPS) showed that the deuterium incorporation at higher temperatures leads to graphene etching. Finally, characterizations using X-ray Absorption Spectroscopy (NEXAFS) showed that deuterium binds to graphene without preferential orientation.

The incidence of gastrointestinal (GI) cancers has been steadily increasing in the UK since the mid 1970’s. These include cancers of the colon and oesophagus. Colon cancers have a high incidence rate, being the fourth most common cancer in the UK for both men and women. Oesophageal cancers in comparison are much rarer, however they have a poor survival rate primarily due to a late diagnosis. The key to improving survival for these cancers and many others is to detect and remove the disease at the early stages, to prevent the cancer from advancing. At present the ‘gold standard’ for diagnosis is a biopsy followed by histopathology. This technique is invasive, time consuming and highly subjective. It is therefore important to look towards non-invasive methods for early and rapid diagnosis. Optical techniques have begun to show such promise. By probing the interactions of tissues with light, diagnostic information is able to be obtained non-invasively. Techniques such as Raman spectroscopy utilise inherent molecular vibrations to extract biochemical information from tissues. Raman spectroscopy, however, is currently fundamentally limited by long acquisition times, due to the inherently weak signals produced. Using coherent Raman techniques such as coherent anti-Stokes Raman scattering (CARS) and stimulated Raman scattering (SRS), the molecular vibrations are coherently driven to provide an enhancement in signal. This thesis explored spectral signatures from snap frozen oesophageal sections in the fingerprint (450 cm-1 to 1850 cm-1) and high wavenumber (2800 cm-1 to 3050 cm-1) regions using spontaneous Raman and compared with spectra from hyperspectral SRS. The diagnostic potential for each technique was assessed for four major pathology groups, normal, Barrett’s oesophagus, dysplasia and adenocarcinoma. Samples were classified using a principal component fed linear discriminant analysis (PCA-LDA) approach with a leave-one-out cross validation. Comparisons were made to haematoxylin and eosin (H&E) stained sections. Raman in the fingerprint region was found to be the most promising for diagnosis. There were minimal changes in the high wavenumber region between pathology groups which was also reflected in the SRS spectra and proved to be insufficient for classification. Further comparisons were made between spontaneous and coherent Raman techniques using frozen colon sections. The morphological and structural information available was explored using a k-means cluster analysis. Both spontaneous and coherent Raman were able to distinguish important structural features in the colon, such as the epithelial cells that form the colonic glands and surrounding connective tissue. Both are important visual markers for cancer diagnosis in the current approach. SRS demonstrated higher spatial resolution and faster acquisition times in comparison to spontaneous Raman. This work has discussed the many advantages of using coherent Raman techniques for tissue applications, but has also highlighted some of the limitations for spectral measurements, arising from the complexity of the system.

O propósito do presente estudo foi analisar o efeito da aplicação de múltiplas camadas consecutivas de dois sistemas adesivos convencionais de dois passos na difusão resinosa e padrão de distribuição dos componentes monoméricos resinosos. Dezesseis terceiros molares humanos hígidos foram tratados com os sistemas adesivos convencionais de dois passos de acordo com as instruções dos fabricantes ou com aplicações em múltiplas camadas consecutivas. Os espécimes foram seccionados paralelamente aos túbulos dentinários e as superfícies submetidas ao polimento com lixas 600, 1200, 1800, 2000 e 4000. Os espectros Raman foram coletados ao longo de uma linha perpendicular a interface adesivo-resina em intervalos de 1 ou 2 m. As medidas de difusão da resina adesiva e distribuição dos componentes monomériccos foram avaliadas pelos picos Raman de 1113 cm-1, 1609 cm-1 e 1454 cm-1. O gradiente de desmineralização usado na determinação da região de hibridização foi avaliado pelo pico de 960 cm-1 da apatita. De acordo com os resultados obtidos, a aplicação de múltiplas camadas apresentou uma tendência de homogeneização dos componentes poliméricos, dependente da composição química da resina adesiva. / The present study analyzed the effect of multiple consecutive adhesive coatings on the pattern of resin diffusion and distribution of monomer components through demineralised dentin after application of two total-etch adhesives. Resin bonded dentin specimens were prepared using two total-etch adhesives (Prime&Bond NT2.1 and Adper Single Bond). The specimens were sectioned parallel to dentinal tubules and the surfaces were polished using 600, 1200, 1800, 2000 and 4000 silicon-carbide papers. Raman spectra were recorded along a line perpendicular to the dentin-resin interface in steps of 1 or 2 m. The measurements of resin diffusion and distribution of monomer components were made on a relative basis by comparing the bands 1113, 1609 and 1454 cm-1. The gradient of dentin demineralization, designed to 960 cm-1, was used to determine the extent of hybridization. From the results of the present study the application of multiple coatings of adhesive showed a trend to produce a homogeneous hybrid layer.

Made available in DSpace on 2016-06-02T20:16:41Z (GMT). No. of bitstreams: 1 DissRROM.pdf: 1359238 bytes, checksum: 5566c1f28c5e34b0134937066b060f35 (MD5) Previous issue date: 2005-03-24 / Financiadora de Estudos e Projetos / In this work, the technique Raman spectroscopy is used in order to study InxGa1-xP films grown with different thickness on GaAs (001). Two sets of samples grown by CBE (Chemical Beam Epitaxy) were analized: the first a GaAs buffer layer of 3000 Ǻ and the second with an 1800 Ǻ buffer layer. Concerning vibrational modes, it was possibleto conclude that for In concentrations around 50 % this alloy has a two mode behaviour. Polarized Raman spectra allowed to estimate the ordering degree of the samples. It was possible to observe strong disorder for all of then, with 0,l26 ≤ η ≤ 0,443. Photoluminescence measurements confirmed the disordering. The stress, the lattice parameters and the concentrationsin the alloys were obtained from the variations of the vibrational modes. The interdifusion of P atoms through the GaAs buffer layer previously observed by X-Ray measurements was confirmed. Finally, a comparative study showed that a sensible difference occur between the vibrational modes of the alloys belonging to each set (with different buffer layer thicknesses). Besides, the absorption coefficients, was also shown to be different for each set. / Neste trabalho a técnica de espectroscopia Raman é utilizada para o estudo de heteroestruturas semicondutoras finas com camadas de espessuras variáveis de InxGa1-xP de rede cristalina casada à do substrato GaAs (001). As amostras forma crescidas pela técnica de Epitaxia por Feixe Químico (CBE do inglês, Chemical Beam Epitaxy). Dois conjuntos diferentes foram analisados, sendo o primeiro com camada buffer de 3000 Å e o segundo com 1800 Å. A análise sobre os modos vibracionais desta liga permitiu concluir que para concentrações de Índio próximas a 50 % ocorre o comportamento denominado a dois modos . Realizamos medidas de Raman polarizado para estimarmos o grau de ordenamento de tais amostras. Pode-se observar uma forte desordem em todas as amostras analisadas, com 0,l26 ≤ η ≥ 0,443. Medidas de Fotoluminescência também foram realizadas confirmando o desordenamento. A partir da variação das freqüências dos modos vibracionais foi feita uma estimativa, através da análise das tensões, dos parâmetros de rede e das concentrações dos elementos que compõem a liga InxGa1-xP de rede casada à do GaAs. Nesta análise estudamos, ainda, a interdifusão de átomos de Fósforo na camada buffer formando a liga GaAs:P. Este fenômeno também foi observado anteriormente, por medidas de raios-X nas mesmas amostras. Por fim, um estudo comparativo levou-nos a concluir que existe uma sensível diferença entre os modos vibracionais das ligas de cada conjunto (com diferentes espessuras da camada buffer ). Além disso os coeficientes de absorção, estimados através da análise dos gráficos da razão das áreas sob a curva dos modos LO-GaAs e LO-GaP em função da espessura do filme, também apresentam-se diferentes para cada conjunto de amostras.

The utilisation of near-infrared Raman spectroscopy for the discrimination of cancers and pre-cancers from normal tissue in the acro-digestive tract has been evaluated. A commercially available Raman microspectrometer has been modified to provide optimum throughput, sensitivity and fluorescence suppression for epithelial tissue measurements. Laser excitation at 830nm was demonstrated to be optimum. High quality (SN ratio 15-20) NIR-Raman spectra have been acquired from oesophageal and laryngeal tissues in time scales under 30 seconds. Pathological groupings covering the full range of normal and neoplastic tissues in the organs of interest have been studied. Both fresh (snap frozen) and formalin fixed tissue samples were investigated, firstly to indicate whether tissue-types can be distinguished in vivo and secondly to demonstrate the use of Raman spectroscopy as a tool for classification in the pathology lab. Results using multivariate statistical techniques to distinguish between spectra from specimens exhibiting different tissue pathologies have been extremely promising. Cross-validation of the spectral predictive models has shown that three groups of larynx tissue can be separated with sensitivities and specificities of between 86 and 90% and 87 and 95% respectively. Oesophageal prediction models have demonstrated sensitivities and specificities of 84 to 97% and 93 to 98% respectively for a three-group consensus model and 73 to 100% and 92 to 100% for an eight-group consensus model. Epithelial tissues including stomach, tonsil, endometrium, bladder and prostate have been studied to identify further tissues where Raman spectroscopy may be employed for detection of disease. Spectra were similar to those obtained from oesophagus and larynx, although sufficiently different for distinct discriminant models to be required. This work has demonstrated the generic nature of Raman spectroscopy for the detection and classification of cancers and pre-cancerous lesions in many tissues. The evidence provided by this study indicates that utilisation of Raman spectroscopy for non-invasive detection and classification of disease is a distinct possibility. Potential difficulties in the transferability from in vitro to in vivo have been evaluated and no significant barriers have been observed. However, further in vivo probe development and optimisation will be required before 'optical biopsy' with Raman spectroscopy can become a reality.

abstract: A lack of adequate energy storage technologies is arguably the greatest hindrance to a modern sustainable energy infrastructure. Chemical energy storage, in the form of batteries, is an obvious solution to the problem. Unfortunately, today’s state of the art battery technologies fail to meet the desired metrics for full scale electric grid and/or electric vehicle role out. Considerable effort from scientists and engineers has gone into the pursuit of battery chemistries theoretically capable of far outperforming leading technologies like Li-ion cells. For instance, an anode of the relatively abundant and cheap metal, magnesium, would boost the specific energy by over 4.6 times that of the current Li-ion anode (LiC6). The work presented here explores the compatibility of magnesium electrolytes in TFSI–-based ionic liquids with a Mg anode (TFSI = bis(trifluoromethylsulfonyl)imide). Correlations are made between the Mg2+ speciation conditions in bulk solutions (as determined via Raman spectroscopy) and the corresponding electrochemical behavior of the electrolytes. It was found that by creating specific chelating conditions, with an appropriate Mg salt, the desired electrochemical behavior could be obtained, i.e. reversible electrodeposition and dissolution. Removal of TFSI– contact ion pairs from the Mg2+ solvation shell was found to be essential for reversible electrodeposition. Ionic liquids with polyethylene glycol chains pendent from a parent pyrrolidinium cation were synthesized and used to create the necessary complexes with Mg2+, from Mg(BH4)2, so that reversible electrodeposition from a purely ionic liquid medium was achieved. The following document discusses findings from several electrochemical experiments on magnesium electrolytes in ionic liquids. Explanations for the failure of many of these systems to produce reversible Mg electrodeposition are provided. The key characteristics of ionic liquid systems that are capable of achieving reversible Mg electrodeposition are also given. / Dissertation/Thesis / Doctoral Dissertation Chemistry 2016

abstract: Nickel-Copper metallization for silicon solar cells offers a cost effective alternative to traditional screen printed silver paste technology. The main objective of this work is to study the formation of nickel silicide contacts with and without native silicon dioxide SiO2. The effect of native SiO2 on the silicide formation has been studied using Raman spectroscopy, Rutherford backscattering spectrometry and sheet resistance measurements which shows that SiO 2 acts as a diffusion barrier for silicidation at low temperatures of 350°C. At 400°C the presence of SiO2 results in the increased formation of nickel mono-silicide phase with reduced thickness when compared to samples without any native oxide. Pre and post-anneal measurements of Suns Voc, photoluminescence and Illuminated lock in thermography show effect of annealing on electrical characteristics of the device. The presence of native oxide is found to prevent degradation of the solar cells when compared to cells without any native oxide. A process flow for fabricating silicon solar cells using light induced plating of nickel and copper with and without native oxide (SiO2) has been developed and cell results for devices fabricated on 156mm wafers have been discussed. / Dissertation/Thesis / Masters Thesis Materials Science and Engineering 2016