Thesis (Ph. D.)--University of Texas at Austin, 2007. / Vita. Includes bibliographical references.

Thesis (M. Eng.). / Written for the Dept. of Electrical and Computer Engineering. Title from title page of PDF (viewed 2008/01/14). Includes bibliographical references.

Thesis (M. S.)--Bioengineering, Georgia Institute of Technology, 2004. / William D. Hunt, Committee Chair ; Allen M. Orville, Committee Member ; Cheng Zhu, Committee Member ; Doug Armstrong, Committee Member ; Lawrence A. Bottomley, Committee Member. Includes bibliographical references.

University, Diss., 2001--München.

Thesis (Ph. D.)--Ohio State University, 2006. / Title from first page of PDF file. Includes bibliographical references (p. 396-405).

Predicting and verifying the tunable optical properties of metal nanostructures is central to designing materials optimized for specific applications. Chemically- deposited nanostructures have been well-studied near the percolation threshold, but at lower surface coverages they exhibit sample-to-sample variations in the optical response. We identify how these variations are driven by the high variability in the particle size distribution in a particular surface coverage range. We then explore film- coupled nanoparticle systems consisting of a silver nanoparticle, thin dielectric spacer layer, and flat silver film, to enable tuning toward the blue and green parts of the spectrum. We use the boundary element method to visualize charge distributions of various resonances. We fabricate samples using thermal evaporation and spin coating methods, and use polarized reflectance spectroscopy to measure their optical response at an ensemble level. We achieve a 532nm resonance for 80nm silver nanoparticles on 13nm PMMA spacers and 100nm silver thin films. The resulting design is a candidate for enhancing fluorescence in a new spectral range. This dissertation includes previously unpublished co-authored material.

Terahertz time-domain spectroscopy (TTDS) is a powerful spectroscopic technique, combining pulsed broadband operation with high sensitivity coherent detection at room temperature. This thesis describes studies of terahertz surface plasmon polariton (SPP) guidance on a range of metamaterial structures using TTDS. Metamaterials are artificial media constructed from sub-wavelength dimension conducting elements which have an electromagnetic response that can be engineered by creating geometrical plasma-like resonances. In this work, high-confinement terahertz waveguiding is achieved by binding SPPs to cavity resonances which spoof the behaviour of intrinsic surface plasmon resonances found at much higher frequencies. The main aim of these studies is to investigate their properties with regard to potential applications in waveguiding and sensing. The first two chapters of this thesis describe the background to the subject. In chapter 3, the construction of a novel, flexible geometry, fibre-coupled TTDS system using hollow-core photonic crystal fibre (HC-PCF) is described. The extension of the system to include a near-field probe for evanescent field characterisation is also discussed. In chapter 4, we present the first direct observation of terahertz SPP propagation on plasmonic metamaterials consisting of copper sheets patterned with two-dimensional arrays of square copper-lined holes. Wavelength-scale field confinement is experimentally observed over an octave in frequency close to the band edge, representing a two order of magnitude increase in confinement compared to a flat metal sheet. In chapter 5, metamaterials consisting of two-dimensional arrays of coaxial apertures are shown to support two spoof plasmon modes below the band edge, enabling wavelength-scale field confinement to be experimentally realised at two distinct frequencies. In chapter 6, we present the first experimental results for terahertz SPP propagation on helical and discretely grooved cylindrical metamaterials termed metawires. In each case the results are compared with numerical simulations.

O estudo de nanopartículas plasmônicas de ouro sob o ponto de vista conceitual foi o foco desta tese, explorando principalmente os efeitos do envoltório molecular e a intensificação dos espectros SERS tendo em vista aplicações em sensoriamento químico. Como moléculas sonda, foram selecionadas espécies multifuncionais, como a 2,4,6-trimercapto-1,3,5-triazina (TMT), 4,5-diamino-2,6- dimercaptopirimidina (DadMcP ou Dad) e a mercaptoetilpirazina (PZT), que apresentam grupos tióis capazes de ancorar nas nanopartículas de ouro, deixando outros sítios livres para interagir com substratos e complexos metálicos. Observou-se que o envoltório molecular formado no método de Turkevich, é bastante dependente das condições de síntese, tendo sido possível detectar a presença do intermediário da reação de oxidação do citrato na superfície das nanopartículas, sob condições controladas, influenciando drasticamente o comportamento SERS. Foi feito um estudo sistemático da molécula sonda 2,4,6-trimercapto-1,3,5-triazina ancorada nas nanopartículas de ouro, tanto por troca da camada passivante (citrato), como por síntese in situ com e sem agente redutor. Esses sistemas foram investigados, sob diferentes condições, como sensores SERS para metais. Esse estudo foi ampliado para a molécula sonda 4,5-diamino-2,6-dimercaptopirimidina (DadMcP), explorando a influência do tempo na coordenação dessa espécie na superfície e o efeito de diferentes eletrólitos nos processos de agregação. Finalmente, foram apresentadas fortes evidências da ocorrência de processos fotoinduzidos envolvendo as nanopartículas funcionalizadas, com destaque para a mercaptoetilpirazina (PZT), cujo comportamento mostrou-se bastante inusitado, gerando filmes fotoagregados sob influência da luz UV com possível aplicação em fotolitografia. / The study of plasmonic gold nanoparticles under the conceptual point of view was the focus of this thesis, exploring mainly, the effects of molecular shell and the intensification of SERS spectra aiming at applications in chemical sensing. For the probe molecules, multifunctional species were selected, such as a 2,4,6-trimercapto- 1,3,5-triazine (TMT), 4,5-diamine-2,6-dimercaptopyrimidine (DadMcP or Dad) and mercaptoethylpyrazine (PZT) which present thiol groups able to anchor onto gold nanoparticles, leaving available sites for further interaction with substrates and metal complexes. It was observed that the molecular shell in Turkevich\'s method is very dependent on the synthesis condition, being possible to detect the intermediate product of citrate oxidation reaction in the nanoparticle surface, under controlled conditions, dramatically influencing the SERS behavior. A systematic study was conduct with the probe molecule 2,4,6-trimercapto-1,3,5-triazine anchored to gold nanoparticles either by changing the passivating layer (citrate), or for in situ synthesis with and without a reducing agent. These systems were investigated under different conditions as SERS sensors for metals. This study was extended to the probe molecule 4,5-diamine-2,6-dimercaptopyrimidine, exploiting the influence of time in the coordination of such species and also the effect of different kinds of eletrolytes in the aggregation process. Finally, it has been presented strong evidences for the occurence of photoinduced processes involving functionalized nanoparticles with emphasis on mercaptoethylpyrazine, whose bahavior has proved to be very unusual, generating photoaggregated films under UV light influence, with possible applications in photolithography.

Law Wing Cheung. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2005. / Includes bibliographical references. / Abstracts in English and Chinese. / Abstract --- p.I / Acknowledgements --- p.V / List of Publications related to this project --- p.VI / Contents --- p.VII / Chapter Chapter 1 --- Introduction --- p.1-1 / Chapter Chapter 2 --- Literature Review / Chapter 2.1 --- Surface Plasmon Waves --- p.2-2 / Chapter 2.2 --- Excitation of Surface Plasmon --- p.2-4 / Chapter 2.2.1 --- Surface Plasmon Coupling Schemes --- p.2-6 / Chapter 2.3 --- Detection Techniques used in SPR sensors --- p.2-13 / Chapter 2.3.1 --- Angular Interrogation --- p.2-14 / Chapter 2.3.2 --- Wavelength Interrogation --- p.2-15 / Chapter 2.3.3 --- Intensity Interrogation --- p.2-16 / Chapter 2.3.4 --- Phase Interrogation --- p.2-16 / Chapter 2.3.5 --- Commercial SPR biosensors --- p.2-18 / Chapter 2.3.6 --- Comparison between Detection Techniques --- p.2-19 / Chapter 2.4 --- Applications of SPR biosensors --- p.2-21 / Chapter Chapter 3 --- Principle of Surface Plasmon Resonance Sensing Technology / Chapter 3.1 --- SPR Phenomenon --- p.3-1 / Chapter 3.2 --- Conditions for Surface Plasmon Resonance --- p.3-5 / Chapter 3.3 --- Wave-vectors --- p.3-7 / Chapter 3.4 --- Surface Plasmon Resonance described by Fresnel's Theory --- p.3-8 / Chapter 3.5 --- Concept of Surface Plasmon Resonance Biosensing --- p.3-10 / Chapter Chapter 4 --- Experiments / Chapter 4.1 --- Highly sensitive differential phase-sensitive surface plasmon resonance biosensor based on Mach-Zehnder configuration --- p.4-1 / Chapter 4.1.1 --- Materials required --- p.4-1 / Chapter 4.1.2 --- Experimental Setup --- p.4-2 / Chapter 4.1.3 --- Principle of Differential Phase Measurement --- p.4-3 / Chapter 4.1.4 --- Photodetector Circuitry --- p.4-6 / Chapter 4.1.5 --- Digital Signal Processing --- p.4-7 / Chapter 4.1.6 --- Polymer based Micro-fluidic System Integrated with SPR Biosensor --- p.4-9 / Chapter 4.2 --- Phase-sensitive Surface Plasmon Resonance Biosensor using the Photoelastic Modulation Technique --- p.4-12 / Chapter 4.2.1 --- Materials required --- p.4-12 / Chapter 4.2.2 --- Experimental Setup --- p.4-13 / Chapter 4.2.3 --- Principle of Photoelastic Modulation Technique and Signal Processing --- p.4-14 / Chapter 4.2.4 --- Operation Principle of Photoelastic Modulator --- p.4-17 / Chapter 4.3 --- Sample Preparations --- p.4-18 / Chapter 4.3.1 --- Glycerin-water Mixtures --- p.4-18 / Chapter 4.3.2 --- "PBS, BSA and BSA antibody" --- p.4-19 / Chapter 4.3.3 --- "RPMI, Trypsin, Cells and SDS" --- p.4-20 / Chapter Chapter5 --- Results amd Discussions / Chapter 5.1 --- Experimental setup I: Highly sensitive differential phase-sensitive surface plasmon resonance biosensor based on Mach-Zehnder configuration --- p.5-1 / Chapter 5.1.1 --- Measuring various glycerin-water concentration mixture with silver-gold sensing layer --- p.5-1 / Chapter 5.1.2 --- Comparison between the sensitivity of our setup and reported setup based on phase detection --- p.5-4 / Chapter 5.1.3 --- Discussion on 0.01° system resolution --- p.5-7 / Chapter 5.1.4 --- Experiment on monitoring BSA-BSA antibody binding reaction --- p.5-9 / Chapter 5.1.5 --- Matching oil and glass slide --- p.5-11 / Chapter 5.1.6 --- Experiments on monitoring BSA-BSA antibody binding reaction with integrated microfluidic system --- p.5-12 / Chapter 5.1.7 --- Experiment on observing cell adhesion properties on gold surface under the influence of trypsin --- p.5-14 / Chapter 5.1.8 --- Discussion on the non-specific binding between trypsin and gold surface --- p.5-16 / Chapter 5.1.9 --- Modifying the gold surface with BSA layer --- p.5-17 / Chapter 5.1.10 --- Experiment on observing cell adhesion properties on the gold surface under the influence Sodium Dodecyl Sulfate (SDS) --- p.5-18 / Chapter 5.2 --- Experimental setup II: Phase-sensitive surface plasmon resonance biosensor using the photoelastic modulation technique --- p.5-21 / Chapter 5.2.1 --- Measurement on difference glycerin-water concentration mixture --- p.5-21 / Chapter 5.2.2 --- Experiment on monitoring BSA-BSA antibody binding reaction --- p.5-23 / Chapter Chapter 6 --- Conclusions and Future Works / Chapter 6.1 --- Conclusions --- p.6-1 / Chapter 6.2 --- Future Works --- p.6-2 / References --- p.R-1 / Appendix / Chapter A. --- Phase Extraction Routine written by Matlab --- p.A-1 / Chapter B. --- Mathematical expressions for calculating the phase angle in the experiment of SPR biosensor using the Photoelastic Modulation Technique --- p.A-6 / Chapter C. --- Relationship between Concentration and Refractive Index of Glycerin-Water Mixture --- p.A-11 / Chapter D. --- Physical Properties of Bovine Serum Albumin --- p.A-12 / Chapter E. --- Simulation Curve written by Matlab --- p.A-13

Detection of oligonucleotide target has been performed with a sandwich assay scheme. We compare the detection performance of strategies using probe oligonucleotide with or without gold nanoparticles (Au-NPs, 20nm) capped on 3'. Our experimental results reveal that while the DNA detection implemented with NIS can provide high sensitivity, both dynamic range and detection limit can be amplified with the aid of Au-NPs on 3' of the probes. The current detection limits of NIS with and without Au-NPs are 0.4 femtomole and 1 nanomole respectively. (Abstract shortened by UMI.) / Finally, this work presents a systematic study of the surface-enhanced Raman-scattering (SERS) properties of nanoparticle island substrates (NIS) and their application for oligonucleotide target detection. To effectively implement SERS on NIS and identify an optimal condition for DNA detection, the relationship between extinction maximum (lambdamax) and SERS enhancement factor (EF) will be explored in detail. This work demonstrates high S/N ratio SERS spectra can be achieved with NIS that has lambdamax located within a spectral window (∼60nm) defined by the excitation wavelength (514nm) and the scattered Raman wavelength. The highest EF measured is about 4x10 8 with a thickness of Ag being 50 A. / In addition, a surface plasmon enhanced ellipsometry (SPEE) biosensor scheme based on the use of a photoelastic modulator (PEM) has been explored. We showed that the polarization parameters of a laser beam, tan psi, cos Delta and ellipse orientation angle &phis;, can be directly measured by detecting the modulation signals at the 1st and 2nd harmonics of the modulation frequency under a certain birefringence geometry. This leads to an accurate measurement of refractive index variations within the evanescent field region close to the gold sensor surface, thereby enabling biosensing applications. Our experimental results confirm that the new scheme offers a decent detection limit of 2x10-7 refractive index unit (RIU) or 5ng/ml of biomolecule solute concentration without any compromise in dynamic range. / We have demonstrated that the sensitivity limit of intensity-based SPR biosensors can be enhanced when we combine the contributions from phase with that of amplitude instead of just detecting the amplitude or phase variation only. Experimental results indicate that an enhancement factor of as much as 20 times is achievable, yet with no compromise in measurement dynamic range. While existing SPR biosensor systems are predominantly based on the angular scheme, which relies on detecting intensity variations associated with amplitude changes only, the proposed scheme may serve as a direct system upgrade approach for these systems. / We have developed a novel design of multi-pass surface plasmon resonance (SPR) biosensor with differential phase interrogation based on multi-pass interferometry. This new configuration provides an intrinsic phase amplification effect of over two-fold by placing the SPR sensor head in a signal arm of the interferometer so that the interrogating optical beam will traverse the sensor surface infinite number of times. Experimental interferometers based on the Michelson and Fabry-Perot configurations have been employed to experimentally verify this amplification effect through the comparison with the Mach-Zehnder configuration. Results obtained from the salt-water mixtures, antibody-antigen, and protein-DNA binding reaction have confirmed the expected phase measurement enhancement. / Yuan, Wu. / Adviser: H. P. Ho. / Source: Dissertation Abstracts International, Volume: 70-06, Section: B, page: 3582. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2008. / Includes bibliographical references (leaves 115-132). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts in English and Chinese. / School code: 1307.