Dissertations / Theses on the topic 'Plasmonic properties'
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Cole, R. M. "Plasmonic properties of metal nanovoids." Thesis, University of Cambridge, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.597832.
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This thesis describes a study into the plasmonic properties of nanostructured metallic films. Structures are produced by electrochemically depositing metal through a self-assembled template of polymer micro-spheres. This versatile technique allows nano-structures made from metals which can be electrodeposited to be produced quickly and cheaply. Geometries ranging from arrays of shallow dishes, to sharp metallic spikes and encapsulated spherical cavities can all be produced on the same sample. This thesis presents an in-depth study into the properties of delocalised and localised surface plasmons on these structures. These plasmons can be tuned in energy by controlling the sample geometry and local dielectric environment. Techniques are explored for modifying the energy, absorption strength and field distribution of plasmon modes for specific applications. With an understanding into the plasmonic properties of the metallic nanostructures, research is undertaken to explore how the associated local electric-field couples to molecules adsorbed onto a sample surface. The role of specific plasmon modes in enhanced Raman scattering is identified, and then optimised using multilayer nanostructures with tailored plasmon modes. Finally, the use of flexible elastomeric substrates for mechanically tuneable plasmonic substrates is explored.
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Dieleman, Frederik. "Quantum properties of plasmonic waveguides." Thesis, Imperial College London, 2017. http://hdl.handle.net/10044/1/49436.
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This thesis investigates properties of quantum states of light while travelling as surface plasmon polaritons in plasmonic waveguides and structures. The bosonic nature of SPPs has been shown in previous work by performing a Hong-Ou-Mandel interference experiment with a plasmonic scattering-based beam splitter. Here, we show the same interference with a higher statistical power thanks to an improved set-up. A visibility of 59 ± 1 % is obtained in the two-photon interference, clearly breaking the classical limit of 50 %. The importance of the phase-relations between the different modes in the beam splitter is experimentally probed. The output state of the interference is then further analyzed by a quantum state tomography set-up. This makes it possible to quantify the entanglement generated in the interference. As the interference happens in the plasmonic beam splitter, this shows, to our knowledge for the first time, entanglement generated in a plasmonic structure. Together with the recent results in terms of entanglement and coherence preservation of SPPs, this clearly shows the potential of quantum plasmonic devices. To move into the realm of applications, we also investigate theoretically the enhancements in sensitivity quantum states of light can deliver for plasmonic sensing. It is shown that despite the losses, quantum metrology techniques can be useful in an interferometer with plasmonic waveguides. Considering the strengths and successes of plasmonic sensing techniques in a wide range of fields, we envision that entangled and squeezed states of light will become a new route to push the limits in sensitivity.
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Peruch, Silvia. "Ultrafast properties of plasmonic nanorod metamaterial." Thesis, King's College London (University of London), 2016. https://kclpure.kcl.ac.uk/portal/en/theses/ultrafast-properties-of-plasmonic-nanorod-metamaterial(d981b5e4-b959-4193-8cf1-219b68de08d6).html.
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Plasmonic metamaterials have customized linear and nonlinear optical properties. This thesis investigates the properties of an anisotropic plasmonic metamaterial, consisting of aligned, interacting gold nanorods, to perform ultrafast light modulation, exploiting the intrinsic Kerr nonlinearity of gold. This e ect is based on an illumination-intensity-dependent change in the gold's permittivity, which takes place on ultrafast timescales and induces the intensity-dependent change of the metamaterial's re ection and transmission. A comprehensive theoretical and numerical analysis of the linear and nonlinear response of various con gurations of the metamaterial is performed and compared to experimental results. A new family of hyperbolic waveguided modes above the e ective plasma frequency, enabled by spatial dispersion, is identi ed. The strong nonlinear response and the dynamic modulation capabilities associated with the excitation of the waveguided modes is investigated. The presence of strong electron temperature gradients in the nanorods induced by a control light is shown to determine a stronger nonlinear modulation and to in uence the dynamic response, leading to subpicosecond time recovery components of the nonlinearity. Weak and strong coupling between molecular excitons and the metamaterial's modes can be achieved using core-shell nanorod geometries. The coherent interaction of molecular J-aggregates with coreshell nanorod arrays is analyzed in both the weak and strong coupling regimes. Subpicosecond components of the modulation are determined in the strong coupling conditions. The design of the optical response of the gold nanorod and core-shell metamaterials is studied through the near- to mid- Infrared, key spectral regions for molecular ngerprinting in chemical sensing and absorption spectroscopy. The applicability limits of the analytic approaches using the quasi-static and e ective medium approximations is tested. The results show great potential of the plasmonic nanorod metamaterial for ultrafast nonlinear optics in free-space and integrated applications, in a broad spectral range.
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Chen, Lihui. "Synthesis and Plasmonic Properties of Copper-based Nanocrystals." 京都大学 (Kyoto University), 2016. http://hdl.handle.net/2433/217134.
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Strandberg, Östman Felicia. "Optical Properties of Plasmonic Ag/Ni Square Nanostructures." Thesis, Uppsala universitet, Materialfysik, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-256885.
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Ching, Suet Ying. "Plasmonic properties of silver-based alloy thin films." HKBU Institutional Repository, 2015. https://repository.hkbu.edu.hk/etd_oa/194.
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The plasmonic properties of silver-based alloy thin films were studied. Silver-ytterbium (Ag-Yb) and silver-magnesium (Ag-Mg) prepared by thermal co-evaporation were investigated extensively for various thin film properties. The optical properties were intensively analyzed and discussed because the dielectric response of a material is particularly significant in terms of its plasmonic properties. The study of silver-based alloy thin films has been mostly about Ag alloying with other transition metals, but the results of Ag-Yb and Ag-Mg in this work showed that the intensity of plasma resonance is tunable, in which the idea may also apply to other silver-rich binary alloy thin films regardless of the kind of second metal components. In our research, the Ag plasma resonance was weakened with respect to the concentration of Yb and Mg in the alloy thin films. The change in the optical characteristics around Ag plasma resonance frequency was attributed to an increase in “resonance damping. This is confirmed from modeling using classical free-electron theory. The increase in the damping was experimentally corroborated by the concentration dependence of electrical conductivity and estimated average crystallite size of Ag-Yb and Ag-Mg thin films. The reduction in electrical conductivity was not only caused by introducing less conductive Yb or Mg but also through disturbing the Ag lattice structure to promote additional electron scattering at grain boundaries. The Ag-Yb and Ag-Mg alloys carried intermediate properties between their pure components despite the presence of Yb or Mg oxides. Besides optical and electrical properties, changes in the electronic work function were also assessed since it is also important in applications. Plasmonic nanostructures and transparent organic light-emitting diodes (OLEDs) were fabricated to demonstrate their potential applications. Two-dimensional disc-arrays nanostructures composed of pure Ag and Ag-Yb were implemented to evaluate the plasmonic properties. The damping loss in Ag-Yb caused weakened coupling of incident photons and surface plasmons when compared to pure Ag without altering the coupling wavelengths, suggesting potential plasmonic materials for tuning the coupling strength of surface plasmons by controlling the concentration of Yb which may also apply to Ag-Mg. Ultrathin Ag-Yb and Ag-Mg films were used as cathodes in transparent OLEDs for demonstration, which was beneficial by virtue of overall device transmittance though sacrificing electrical conduction leading to poor light emission unless inserting additional ultrathin lithium fluoride to modify the ultrathin cathodes.
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Hung, Yu-Ju. "Studies of the optical properties of plasmonic nanostructures." College Park, Md.: University of Maryland, 2007. http://hdl.handle.net/1903/7735.
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Thesis (Ph. D.) -- University of Maryland, College Park, 2007.Thesis research directed by: Dept. of Electrical and Computer Engineering. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.
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Kolkowski, Radoslaw. "Studies of nonlinear optical properties of plasmonic nanostructures." Thesis, Université Paris-Saclay (ComUE), 2016. http://www.theses.fr/2016SACLN001/document.
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Le but de cette thèse et de la recherche associée est une démonstration des avantages d’une combinaison de propriétés inhabituelles de nanostructures plasmoniques avec des aspects parmi les plus intéressants de l’optique non-linéaire. Pour cet effet, la modélisation analytique et numérique a été combiné avec le travail expérimental, qui comprenait la production de nanostructures et les mesures effectuées au moyen de la microscopie confocale non-linéaire résolue en polarisations et de la technique Z-scan modifiée (nommée “f-scan”).Il a été montré que l’anisotropie efficace de génération de seconde-harmonique dans les cristaux plasmoniques (formés par des réseaux rectangulaires de cavités tétraédriques sur une surface d’argent) peut être contrôlée par un choix approprié des paramètres de maille. Il a aussi été montré que cette anisotropie provient principalement d’une structure de bande photonique elle-même anisotrope, présentant une bande interdite plasmonique avec des états plasmoniques en bord de bande, permettant de renforcer le champ électrique local. Les arrangements chiraux bidimensionnels de nanoparticules triangulaires d’or, forment des “meta-molécules” plasmoniques énantiomériques, ont été analysés par microscopie non-linéaire à la lumière polarisée circulairement et par modélisation numérique, révélant un fort effet chiroptique par génération de seconde harmonique en rétro-réflexion. La petite taille des énantiomères uniques permet de créer “des filigranes” (“watermarks”) codés par la chiralité des meta-molécules, qui peuvent être lu par imagerie de la génération de seconde harmonique excitée par un rayon polarisé circulairement. Les caractéristiques quantitatives de la non-linéarité optique du troisième ordre et de l’efficacité d’absorption saturable des solutions aqueuses de fragments de graphène et de graphène dopé par des nanoparticules d’or a été effectuée par une nouvelle technique “f-scan”, qui a été créée et développée par incorporation d’une lentille à distance focale accordable dans une technique de Z-scan traditionnelle. Ces études ont montrées que le graphène présente une absorption saturable ultra-rapide très efficace, qui est parfois convertie en absorption saturable inverse. Il apparaît alors qu’une décoration du graphène par des nanoparticules d’or peut causer une légère amélioration du paramètre d’efficacité d’absorption saturable dans la plage spectrale de leurs résonances plasmoniques. En résumé, cette thèse présente une variété de propriétés optiques non-linéaires apparaissant dans les nanostructures plasmoniques. Différentes possibilités de contrôle de ces propriétés au moyen d’une démarche de nano-ingénierie, soutenue par des modélisations à la fois analytique et numérique ont été démontrées et analysées. Ces travaux ouvrent la voie à la fabrication et à l‘optimisation sur mesure de nouveaux nano-matériaux et nano-dispositifs photoniques reposant sur des effets de nano-plasmonique non-linéaireThe aim of this thesis and the underlying research work is to demonstrate the benefits emerging from combination of the peculiar properties of plasmonic nanostructures with the most interesting aspects of nonlinear optics. For this purpose, analytical and numerical modeling was combined with experimental work, which included nanofabrication and measurements performed by means of polarization-resolved nonlinear confocal microscopy and by modified Z-scan technique (called "f-scan").It has been shown that the effective anisotropy of the second-harmonic generation in plasmonic crystals (formed by rectangular arrays of tetrahedral recesses in silver surface) can be controlled by proper choice of lattice constants. It also has been shown that this anisotropy arises mainly from the anisotropic photonic band structure, exhibiting plasmonic band gap with plasmonic band edge states, enabling enhancement of the local electric field.Two-dimensional chiral arrangements of triangular gold nanoparticles, forming plasmonic enantiomeric "meta-molecules", have been studied by nonlinear microscopy operating with circularly polarized light and by numerical modeling, revealing strong chiroptical effect in backscattered second-harmonic radiation. Small size of individual enantiomers allows to create "watermarks", encoded by the chirality of meta-molecules, which can be readout by imaging of second-harmonic generation excited by circularly polarized laser beam.Quantitative characterization of the third-order optical nonlinearity and saturable absorption efficiency of aqueous solutions of graphene and gold-nanoparticle decorated graphene has been performed by novel "f-scan" technique, which has been created and developed by incorporation of a focus-tunable lens into traditional Z-scan. These studies have shown that the graphene exhibits very efficient ultrafast saturable absorption, which is occasionally suppressed by reverse saturable absorption. Moreover, it turns out that decoration of graphene by gold nanoparticles may cause a slight improvement of the saturable absorption efficiency parameter within spectral range of their plasmon resonances.In summary, the following thesis presents various nonlinear optical properties of plasmonic nanostructures. Different possibilities of controlling these properties by means of nano-engineering, supported by analytical and numerical modeling, is also analyzed and demonstrated. This work opens up new perspectives for fabrication and rational design of novel photonic nano-materials and nano-devices based on nonlinear nanoplasmonic phenomena
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MAGNOZZI, MICHELE. "Temperature-dependent optical properties of composite plasmonic nanomaterials." Doctoral thesis, Università degli studi di Genova, 2019. http://hdl.handle.net/11567/941310.
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FERRERA, MARZIA. "Local optical properties of 2D semiconductor/plasmonic heterostructures." Doctoral thesis, Università degli studi di Genova, 2022. http://hdl.handle.net/11567/1077989.
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The possibility to control the properties of low-dimensional semiconductors via the exploitation of properly engineered architectures shows promising implications for several potential applications in the fields of optoelectronic and quantum technologies. Among the plethora of semiconducting materials, two-dimensional group 6 transition metal dichalcogenides (TMDCs), when thinned down to the three-atoms-thick monolayer (ML), exhibit a transition of the electronic bandgap from indirect to direct, with the bandgap energy falling within the visible spectral range. This, together with other singular properties, makes TMDCs extremely appealing light-sensitive materials for optoelectronics and photonics applications. Among several strategies to enhance light-matter interaction in ultrathin TMDC films, the electromagnetic field confinement and amplification typical of nano-sized metallic objects supporting localized surface plasmon resonances, i.e. light-induced collective electronic oscillations, can significantly strengthen the interaction of atomically-thick TMDCs with light, with the opportunity to exploit hybrid systems to realize plasmon-enhanced devices. In addition, the structural, electronic and optical properties of 2D TMDCs can be properly manipulated via their integration with plasmonic materials. Moreover, strongly-coupled exciton-plasmon systems can be realized by combining few- and single-layer TMDCs with ad-hoc designed plasmonic nanostructures with promising implications both for fundamental research and quantum-based applications.
In this context, the research activity reported in this thesis has dealt with the study of the optical properties of spatially-confined systems. Two main classes of nanomaterials were investigated, namely noble metal nanostructures, with specific interest on their plasmonic and thermoplasmonic properties, and 2D TMDCs, with a focus on their excitonic properties.
This manuscript mainly deals with the local optical properties which arise when integrating ML-TMDCs with plasmonic nanosystems to form hybrid structures. The experimental investigations on the hybrid systems have in common the exploitation of laterally-resolved optical techniques with micrometric and even nanometric spatial resolution.
In detail, I will show how the combination of imaging spectroscopic ellipsometry and imaging photoluminescence spectroscopy can provide a complete picture of the local excitonic properties of TMDC flakes (WS2 in this case) grown by chemical vapour deposition. Deep knowledge on the local excitonic properties of 2D TMDCs proved fundamental for studying how their properties can be tailored by coupling with plasmonic materials. In this thesis, hybrid systems with a double-layer architecture (i.e. ML-TMDC/plasmonic substrate) were realized for two main experimental investigations. The first study dealt with the role played by the morphology of the plasmonic substrate, an ultra-dense array of Au NPs (approximately 10^3 NPs/µm^2), in affecting the plasmon-exciton interaction. In the second experiment, a 2D TMDC/plasmonic heterostructure was implemented as a system to probe the capabilities of tip-enhanced photoluminescence spectroscopy (TEPL) in mapping at the nanoscale the light-emission related properties of ML-TMDCs onto a plasmonic substrate. The last part of the thesis is dedicated to experimental investigations on the ultrafast temperature evolution of impulsively-excited plasmonic systems by means of pump-probe techniques. Two model-free approaches are presented for the direct assessment of the temporal evolution of the electron gas temperature after impulsive photoexcitation of metallic NPs. More in general, the results obtained from these last experimental studies pave the way for the assessment of the relaxation dynamics within physical systems and are inspiring towards further exploration on the phenomena which arise following photoexcitation of low-dimensional semiconductor/plasmonic heterostructures taking place on time scales of the fs-ps, such as the processes of charge and/or energy transfer and those related to hot electrons.
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Woollacott, Claire. "Electronic and plasmonic properties of real and artificial Dirac materials." Thesis, University of Exeter, 2015. http://hdl.handle.net/10871/18227.
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Inspired by graphene, I investigate the properties of several different real and artificial Dirac materials. Firstly, I consider a two-dimensional honeycomb lattice of metallic nanoparticles, each supporting localised surface plasmons, and study the quantum properties of the collective plasmons resulting from the near field dipolar interaction between the nanoparticles. I analytically investigate the dispersion, the effective Hamiltonian and the eigenstates of the collective plasmons for an arbitrary orientation of the individual dipole moments. When the polarisation points close to normal to the plane the spectrum presents Dirac cones, similar to those present in the electronic band structure of graphene. I derive the effective Dirac Hamiltonian for the collective plasmons and show that the corresponding spinor eigenstates represent chiral Dirac-like massless bosonic excitations that present similar effects to those of electrons in graphene, such as a non-trivial Berry phase and the absence of backscattering from smooth inhomogeneities. I further discuss how one can manipulate the Dirac points in the Brillouin zone and open a gap in the collective plasmon dispersion by modifying the polarisation of the localized surface plasmons, paving the way for a fully tunable plasmonic analogue of graphene. I present a phase diagram of gapless and gapped phases in the collective plasmon dispersion depending on the dipole orientation. When the inversion symmetry of the honeycomb structure is broken, the collective plasmons become gapped chiral Dirac modes with an energy-dependent Berry phase. I show that this concept can be generalised to describe many real and artificial graphene-like systems, labeling them Dirac materials with a linear gapped spectrum. I also show that biased bilayer graphene is another Dirac material with an energy dependent Berry phase, but with a parabolic gapped spectrum. I analyse the relativistic phenomenon of Klein Tunneling in both types of system. The Klein paradox is one of the most counter-intuitive results from quantum electrodynamics but it has been seen experimentally to occur in both monolayer and bilayer graphene, due to the chiral nature of the Dirac quasiparticles in these materials. The non-trivial Berry phase of pi in monolayer graphene leads to remarkable effects in transmission through potential barriers, whereas there is always zero transmission at normal incidence in unbiased bilayer graphene in the npn regime. These, and many other 2D materials have attracted attention due to their possible usefulness for the next generation of nano-electronic devices, but some of their Klein tunneling results may be a hindrance to this application. I will highlight how breaking the inversion symmetry of the system allows for results that are not possible in these system's inversion symmetrical counterparts.
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Liu, Junjun. "Optical properties of chiral plasmonic nanoparticles and mesoporous silicon nanowires." HKBU Institutional Repository, 2017. https://repository.hkbu.edu.hk/etd_oa/385.
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Structural engineering plays an essential role in controlling the optical properties of nanostructures, which are of fundamental and practical interest in nanoscience and technology. In this study, two kinds of nanostructural engineering were investigated systematically to enrich nano-optics research: structural helicity was imposed on plasmonic nanoparticles (NPs) with chiroptical activity engineerable in the ultraviolet (UV)-visible region, and porosification was imposed on silicon nanowires (SiNWs) to tune optical interaction and photoluminescence (PL).. The generation of helical metamaterials, which have strong, engineerable chiroptical activity in the UV-visible region, has attracted increasing attention due to the manipulation of the circular polarization state of light to develop diverse homochirality-associated bio-applications. Glancing-angle deposition with fast substrate rotation is performed to generate plasmonic helical NPs (PhNPs) with a helical pitch (P) of less than 10 nm, which is so much smaller than the wire diameter (d) that the PhNPs appear to be achiral NPs. The PhNPs exhibit chiroptical activity that originates intrinsically from hidden helicity, characterized by circular dichroism (CD). With an increase of P from 3 to 66 nm, the plasmonic CD signals barely shift but show a logarithmic amplification. PhNPs made of aluminum, silver, and copper exhibit a stable chiroptical response from the deep UV (~220 nm) region to the visible region. When an achiral plasmonic nanostructure guest is coated on a PhNP host (i.e., a chiral host@achiral guest nanostructure is created), the achiral guest becomes chiroptically active due to helicity transfer from the chiral host to the achiral guest. Such a helicity transfer can be generally adapted to diverse plasmonic metals to tailor the plasmonic chiroptical response flexibly in the UV-visible region. Furthermore, an amplification of the near-field optical chirality induced by the PhNPs would pave a novel way to performing asymmetric syntheses, for which investigations are currently lacking. Silver PhNPs are used to effectively mediate the enantioselective photocyclodimerization of 2-anthracenecarboxylate: left-handed silver PhNPs lead to a positive ee (enantiomeric excess) value, and right-handed silver PhNPs give rise to a negative ee value. The enantioselectivity is enhanced with a decreasing P. The PhNP-mediated enantioselective photocyclodimerization is ascribed to the synergistic contribution from chirally helical surface-induced enantioselective adsorption of 2-anthracenecarboxylate and chiroptically active nanoplasmon-enhanced optical chirality of near-field circularly polarized light.. Metal-assisted chemical etching (MACE) is carried out to generate mesoporous SiNWs (mp-SiNWs) with mesopores from 2 to 50 nm. The porosification imposes two prominent properties onto SiNWs: a high surface-to-volume ratio and quantum confinement ascribed to the shrinkage of silicon skeletons. Hence, engineering the porosity of SiNWs is of fundamental importance. Here, a new method is devised to reduce the porosity of mp-SiNWs without changes in the MACE conditions. After generating the mp-SiNWs with high porosity, the mp-SiNWs are removed from the mother Si wafers with sticky tape, followed by MACE under the same conditions to produce low-porosity mp-SiNWs. Less porous mp-SiNWs reduce optical scattering from the porous Si skeletons and vertically protrude on the wafer without aggregation to facilitate optical trapping. Consequently, low-porosity mp-SiNWs effectively reduce UV-visible reflection loss. Furthermore, optical applications require surface modification of mp-SiNWs with functional chemicals, which has a prerequisite to passivate mp-SiNWs with H-termination using 5% hydrogen fluoride. 40% NH4F, which has been widely used to passivate Si(111) wafers with H-termination, tends to unexpectedly etch mp-SiNWs attributed to surface F-termination caused by the nucleophilic attack of F− anions to Si atoms. It has been used to study systematically the NH4F-etching rate as a function of the doping levels of SiNWs, surface crystalline orientations, and porosity. At a modest temperature of 110°C, 1,4-diethynylbenzene (DEBZ) is grafted via monosilylation grafted on H-terminated mp-SiNWs. The modified mp-SiNWs with chemically active monolayers is facilely subjected to further chemical modification and surface functionalization. In addition, the monosilylation encodes mp-SiNWs with PL of DEBZ, opening a door to flexible engineering of PL of mp-SiNWs for optoelectronic and bio-detection applications.
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Nguyen, Thi Tuyet Mai. "Elaboration and optical properties of thermosensitive plasmonic hybrid nanostructures." Sorbonne Paris Cité, 2015. http://www.theses.fr/2015USPCC285.
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La conception de nanomateriaux hybrides multifonctionnels est un champ de recherche en plein essor. Notamment, la combinaison de polymères thermosensibles et de nanoparticules d'or (GNPs) offre des perspectives prometteuses pour l'élaboration de matériaux à grande valeur ajoutée pour des applications dans le domaine des capteurs, du biomédical et de la catalyse. Dans ce travail de thèse, nous avons élaboré des nanostructures hybrides combinant nanoparticules d'or et poly(N-isopropylacrylamide) (PNIPAM), en s'appuyant sur des techniques de lithographies et de polymérisation radicalaire contrôlée. Grâce à ces deux techniques, il a été possible de faire varier à la fois le degré d'anisotropie des nanoparticules d'or et l'épaisseur des chaînes de PNIPAM, de façon parfaitement contrôlée. L'influence de ces deux paramètres sur la sensibilité des nanostructures plasmoniques à leur environnement local et plus particulièrement à des changements de température a ainsi pu être étudiée. De plus, en utilisant les nanoparticules d'or comme nanosources de chaleur, nous avons pu induire localement des élévations de température très rapides et déterminer les échelles de temps du processus de transition de phase des brosses de PNIPAM greffées. Dans un deuxième temps, nous avons cherché à exploiter ces structures hybrides stimulables pour la détection de molécules par SERS ou pour sonder l'isomerisation de molécules photochromes d'azobenzene, par spectroscopie UV-visible. Dans un dernier temps, nous avons proposé une nouvelle stratégie de greffage de couches organiques sur les nanostructures d'or, spatialement sélective, induite par plasmon. Le greffage de groupes aryles dérivant de sels de diazonium se produit spécifiquement dans les régions d'exaltation maximale du champ électromagnétique autour des GNPs. Cette nouvelle approche ouvre de nombreuses perspectives pour le confinement à l'échelle nanométrique de couches de polymères greffées sur des nanostructures plasmoniquesDriven by the search for hybrid multifunctional nanomaterials with interesting and unique properties, we have considered the association of thermoresponsive pNIPAM with gold nanoparticles (GNPs), which ideally combine the responsiveness of pNIPAM with the optical, catalytic or photothermal properties of GNPs. In this PhD dissertation, we addressed strong synergies between GNPs and PNIPAM in hybrid GNP@PNIPAM nanostructures, obtained from the grafting of PNIPAM brushes on lithographie GNPs arrays. Firstly, the hybrid nanostructures including gold nanorod (GNRs) arrays coated by pNIPAM allowed us to investigate properly the influence of the GNPs anisotropy and the polymer thickness on the sensitivity to the local environment. The optimization of the GNR's aspect ratio r and the pNIPAM thickness, to provide a maximum of LSP shift upon a change in temperature,is obtained for r'-2. 4-2. 6 and hPNIPAM —25 nm, respectively. Secondly, such hybrid nanostructures allowed us to measure the phase transition time of pNIPAM brushes, 160±20 Ils for a 30 nm pNIPAM layer. Particularly, we used the pNIPAM brushes as a dynamic linker in order to control the coupling of plasmonic nanoparticles and the sensitive detection of Nile blue A molecules by SERS. Such hybrid nanostructures were also applied to probe the isomerization of azobenzene derived molecules by UV-visible spectroscopy. Interestingly, we developed a new strategy for the selective plasmon-mediated chemical grafting of aryl layers derived from diazonium salts on gold nanostripe arrays. This grafting occurs specifically in the regions of maximum field enhancement of GNPs. In perspective, this strategy is expected to allow us controlling the grafting of pNIPAM brushes, and thus the binding of analyte molecules to selected locations on the GNP surface with well-defined near-field enhancement factor for quantitative SERS measurements
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Agreda, Adrian. "Electrical control of the nonlinear properties of plasmonic nanostructures." Thesis, Bourgogne Franche-Comté, 2020. http://www.theses.fr/2020UBFCK010.
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Ce travail rassemble les technologies de nanoélectronique et de nano-photonique pour créer un dispositif électro-plasmonique dont les propriétés optiques linéaires et non linéaires sont contrôlées électriquement. Ici, nous présentons la première démonstration de la modulation de photoluminescence non linéaire par des moyens électriques dans un cas d'étude simple. A cette fin, les nanoantennes plasmoniques sont interfacées avec des connexions électriques induisant des régions localisées d’accumulation et de déplétion d'électrons et affectant ainsi la réponse optique. De plus, une analyse complète de la photoluminescence non linéaire dans les nanofils plasmoniques est réealisée. La délocalisation et le transport des non-linéarités apportées par de telles structures permettent l’activation à distance des signaux. Différents aspects, dont les mécanismes sous-jacents à la modulation électrique et les processus dictant la généeration de photoluminescence non linéaire, sont systématiquement explorésThis work brings nano-electronics and nano-photonics technologies together to create an electron- plasmon device whose linear and nonlinear optical properties are electrically controlled. Here, we present the first demonstration of nonlinear photoluminescence modulation by electrical means in an uncluttered configuration. To this purpose, plasmonic nanoantennas are interfaced with elec- trical connections inducing localized regions of electron accumulation and depletion and therefore affecting the optical response. Additionally, a complete analysis of the nonlinear photoluminescence in plasmonic nanowires is carried out. The delocalization and transport of nonlinearities provided by such structures allow the remote activation of the signals. Different aspects including the un- derlying mechanisms behind the electrical modulation and the processes dictating the nonlinear photoluminescence generation are systematically explored
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Ji, Botao. "Synthesis and optical properties of plasmonic fluorescent quantum dots." Thesis, Paris 6, 2014. http://www.theses.fr/2014PA066674/document.
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Grâce aux plasmons de surface des nanoparticules métalliques et aux propriétés optiques et électroniques des quantum dots (QDs), les nanostructures QD/métal suscitent beaucoup d'intérêt. Cependant, bien que prometteurs, les hybrides QD/or colloïdaux n'ont été que rarement obtenus.Nous avons mis au point la première méthode de synthèse généralisée conduisant à des structures hybrides cœur/coque/coque QD/SiO2/Au (appelées QDs dorés). Tout d'abord, les QDs hydrophobes sont encapsulés individuellement dans des billes de silice par émulsion inverse. Les nanoparticules obtenues sont ensuite recouvertes d'une coque d'or continue via un processus de dépôt en solution. Les épaisseurs de silice et d'or peuvent être ajustées indépendamment aux dimensions voulues. Nous avons montré que les QDs dorés individuels à base de QDs CdSe/CdS à coque épaisse possèdent une émission stable et poissonienne à température ambiante et sont très photostables. Cette nouvelle structure se comporte comme un résonateur plasmonique avec un facteur de Purcell élevé (~6), en très bon accord avec les simulations.Nous présentons également des auto-assemblages de QDs hydrophobes en superparticules (SPs). Un choix judicieux de QDs donne aux SPs des propriétés exceptionnelles telles qu'une émission de fluorescence intense, non-clignotante et multicolore. Des SPs multifonctionnelles peuvent aussi être obtenues en associant des nanocristaux magnétiques et fluorescents. La croissance d'une coque de silice sur les SPs a permis d'augmenter leur stabilité et nous avons démontré que cette couche de silice pouvait être recouverte d'une coque d'or pour améliorer la photostabilité et la biocompatibilité de ces SPsDue to the surface plasmons in metallic nanostructures and the exceptional optical and electrical properties of colloidal semiconductor quantum dots (QDs), QD/metal hybrid nanostructures attract much attention. However, although these structures are very promising, colloidal single QD/gold hybrids have rarely been synthesized.We managed to develop for the first time a generalized synthetic route to synthesize a QD/SiO2/Au core/shell/shell hybrid structure (golden QDs). First, hydrophobic QDs are individually encapsulated in silica beads via reverse microemulsion. The obtained QD/SiO2 nanoparticles are then coated with a continuous gold nanoshell using a solution deposition process. The thicknesses of the silica and the gold layers can be tailored independently to various dimensions. We showed that single golden thick-shell CdSe/CdS QDs provide a system with a stable and poissonian emission at room temperature and a high photostability. This novel hybrid golden QD structure behaves as a plasmonic resonator with a strong (~ 6) Purcell factor, in very good agreement with simulations. We also present the self-assembly of hydrophobic QDs into colloidal superparticles (SPs). With a fine choice of QDs, SPs could indeed possess outstanding properties including non-blinking fluorescence, high fluorescence intensity and multi-color emission. Multi-functional SPs could also be obtained by mixing fluorescent or magnetic nanocrystals. The subsequent growth of a silica shell on the SPs allowed an enhancement of their stability and we demonstrated this silica shell could itself be covered by a gold nanoshell to further improve the SPs photostability and biocompatibility
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Pechprasarn, Suejit. "Analysis of sensitivity and resolution in plasmonic microscopes." Thesis, University of Nottingham, 2012. http://eprints.nottingham.ac.uk/13100/.
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Surface plasmons (SP) are guided electromagnetic wave propagating along the surface of metal. The properties of SP are affected by the material attached to the metallic surface so they can be used as a very sensitive sensor capable of detecting the deposition of subnanometric layers of dielectric. SP has been widely investigated for biosensor applications and the theory is well established. Although SP sensors have been well studied, integrating the SP to a microscope is a relatively young field. Since the SPs are surface waves; microscopy techniques to optimise the SP microscope performance will require totally different techniques to non-surface wave microscopy. This thesis develops a theoretical framework to understand different types of SP microscope setups through the rigorous diffraction theory. The framework analyses the diffraction process through rigorous wave coupled analysis (RCWA) and a software package processes the diffracted orders to recover the microscope response for a range of different systems. In this thesis I will investigate the non-interferometric SP microscope, interferometric SP microscope and confocal SP microscope. I will show that the non-interferometric system exhibits a trade-off between lateral resolution and sensitivity, where an image obtained with a good contrast will have low lateral resolution. In order to get around the trade-off, the interferometric system can be employed; however, the main challenge for the interferometric setup is its optical alignment. I will show that a confocal SP microscope, which has been developed as a part of this thesis, can simplify the complexity of the interferometric system and give similar measurement performance. For the interferometric and confocal systems, the SP measurements are normally carried out through the interference signal, which is interference between a reference beam and the SP. I will suggest a method to extract SP propagation parameters from the interference signal by employing a spatial light modulator and also show that the SP propagation parameters do not only give us some insight to the SP effect for the interferometric system, but also gives us a new imaging mode to improve the resolution.
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DeSantis, Christopher John. "Manipulating the architecture of bimetallic nanostructures and their plasmonic properties." Thesis, Indiana University, 2015. http://pqdtopen.proquest.com/#viewpdf?dispub=3665584.
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There has been much interest in colloidal noble metal nanoparticles due to their fascinating plasmonic and catalytic properties. These properties make noble metal nanoparticles potentially useful for applications such as targeted drug delivery agents and hydrogen storage devices. Historically, shape-controlled noble metal nanoparticles have been predominantly monometallic. Recent synthetic advances provide access to bimetallic noble metal nanoparticles wherein their inherent multifunctionality and ability to fine tune or expand their surface chemistry and light scattering properties of metal nanoparticles make them popular candidates for many applications. Even so, there are currently few synthetic strategies to rationally design shape-controlled bimetallic nanocrystals; for this reason, few architectures are accessible. For example, the "seed-mediated method" is a popular means of achieving monodisperse shape-controlled bimetallic nanocrystals. In this process, small metal seeds are used as platforms for additional metal addition, allowing for conformal core@shell nanostructures. However, this method has only been applied to single metal core/single metal shell structures; therefore, the surface compositions and architectures achievable are limited. This thesis expands upon the seed-mediated method by coupling it with co-reduction. In short, two metal precursors are simultaneously reduced to deposit metal onto pre-formed seeds in hopes that the interplay between two metal species facilitates bimetallic shell nanocrystals. Au/Pd was used as a test system due to favorable reduction potentials of metal precursors and good lattice match between Au and Pd. Alloyed shelled Au@Au/Pd nanocrystals were achieved using this "seed-mediated co-reduction" approach. Symmetric eight-branched Au/Pd nanocrystals (octopods) are also prepared using this method. This thesis investigates many synthetic parameters that determine the shape outcome in Au/Pd nanocrystals during seed-mediated co-reduction. Plasmonic, catalytic, and assembly properties are also investigated in relation to nanocrystal shape and architecture. This work provides a foundation for the rational design of architecturally defined bimetallic nanostructures.
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Kamakura, Ryosuke. "Fabrications and optical properties of plasmonic arrays without noble metals." Kyoto University, 2018. http://hdl.handle.net/2433/232046.
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Sediq, Khalid. "The optical properties of photonic-crystal nanocavities containing plasmonic nanoparticles." Thesis, University of Sheffield, 2016. http://etheses.whiterose.ac.uk/12324/.
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Pellegrini, Giovanni. "Modeling the optical properties of nanocluster-based functional plasmonic materials." Doctoral thesis, Università degli studi di Padova, 2008. http://hdl.handle.net/11577/3425967.
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Optical properties of nanocluster-based plasmonic materials were studied along this thesis by the Generalized Multiparticle Mie approach. Far- and local-field optical properties of basic plasmonic structures such as sphere dimers and chains were successfully analyzed as a function of their composition and their topological features.
The provided physical insight is then exploited in the modeling of strongly coupled complex structures obtained by ion beam processing. These systems were called nanoplanets since they are constituted by a large central cluster surrounded by small satellite ones very close to its surface. Nanoplanets show
extremely interesting far- and local-field properties which may be carefully tailored by varying the ion beam synthesis conditions. GMM theory allowed to establish that the strong interparticle coupling is at the base of their peculiar
optical features. Finally multiple coupled cluster are proposed as efficient nanoantennae. Nanoparticle dimers were proved to provide extremely efficient broadband light extraction. If regular sphere array are used instead, broadband limitation imposed by isolated antennae may be overcome and tunable wavelength selective recombination rate enhancement is obtained.
Overall this thesis gives an interesting insight in the plasmonic properties of functional multiple coupled cluster nanostructures.
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Pathak, Nilesh Kumar. "Study of plasmonic properties of metal nanoparticles and its applications." Thesis, IIT Delhi, 2016. http://localhost:8080/xmlui/handle/12345678/7040.
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Barbosa, Neira Andres David. "Analysis and characterization of the nonlinear optical properties of plasmonic metamaterials." Thesis, King's College London (University of London), 2015. http://kclpure.kcl.ac.uk/portal/en/theses/analysis-and-characterization-of-the-nonlinear-optical-properties-of-plasmonic-metamaterials(aa1f642a-eb29-4a21-b599-e5d3b7acddad).html.
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Metamaterials are materials whose optical properties can be designed through the accurate engineering of their structure on the subwavelength scale. They have enabled the discovery and study of a variety of interesting new optical properties not normally present in materials found in nature. Furthermore, by designing the local electromagnetic field distributions of such metamaterials, it is possible to engineer not only their linear optical properties but also their nonlinear response, which is fundamental for the development of nonlinear and active nanophotonics for all-optical information processing. In this thesis I will show that plasmonic metamaterials based on metallic nanorod arrays can be designed to have strong third-order nonlinear optical response originating from the nonlinearity of the plasmonic component of the metamaterial, allowing nonlinear processes to be more energy efficient and highly integrated. The nonlinearity will be experimentally determined through the z-scan technique and explained by numerical modeling in both effective medium and fullvectorial simulations. Enhancements of about 50 times for the nonlinear absorption and about 10 times for the nonlinear refraction are observed compared to a smooth metal film. Furthermore, the properties of waveguides comprised of the nanorod metamaterial are studied and the possibility of their integration in conventional Si photonic waveguides is demonstrated. In this context, two all-optical modulators using plasmonic metamaterials are designed, operating in the hyperbolic and epsilon near-zero regimes. Both designs are highly integrated and energy efficient having footprints of 300x440x600 nm3 and 300x180x340 nm3 with an energy consumption of 3.7 pJ/bit and 0.6pJ/bit respectively. The obtained results show great opportunities for nonlinear metamaterials in nanophotonic applications.
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Guidez, Emilie Brigitte. "Quantum mechanical origin of the plasmonic properties of noble metal nanoparticles." Diss., Kansas State University, 2014. http://hdl.handle.net/2097/17314.
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Doctor of PhilosophyDepartment of Chemistry
Christine M. Aikens
Small silver and gold clusters (less than 2 nm) display a discrete absorption spectrum characteristic of molecular systems whereas larger particles display a strong, broad absorption band in the visible. The latter feature is due to the surface plasmon resonance, which is commonly explained by the collective dipolar motion of free electrons across the particle, creating charged surface states. The evolution between molecular properties and plasmon is investigated. Time-dependent density functional theory (TDDFT) calculations are performed to study the absorption spectrum of cluster-size silver and gold nanorods. The absorption spectrum of these silver nanorods exhibits high-intensity longitudinal and transverse modes (along the long and short axis of the nanorod respectively), similar to the plasmons observed experimentally for larger nanoparticles. These plasmon modes result from a constructive addition of the dipole moments of nearly degenerate single-particle excitations. The number of single-particle transitions involved increases with increasing system size, due to the growing density of states available. Gold nanorods exhibit a broader absorption spectrum than their silver counterpart due to enhanced relativistic effects, affecting the onset of the longitudinal plasmon mode. The high-energy, high-intensity beta-peak of acenes also results from a constructive addition of single-particle transitions and I show that it can be assigned to a plasmon. I also show that the plasmon modes of both acenes and metallic nanoparticles can be described with a simple configuration interaction (CI) interpretation. The evolution between molecular absorption spectrum and plasmon is also investigated by computing the density of states of spherical thiolate-protected gold clusters using a charge-perturbed particle-in-a-sphere model. The electronic structure obtained with this model gives good qualitative agreement with DFT calculations at a fraction of the cost. The progressive increase of the density of states with particle size observed is in accordance with the appearance of a plasmon peak. The optical properties of nanoparticles can be tuned by varying their composition. Therefore, the optical behavior of the bimetallic Au[subscript](25-n)Ag[subscript]n(SH)[subscript]18[superscript]- cluster for different values of n using TDDFT is analyzed. A large blue shift of the HOMO-LUMO absorption peak is observed with increasing silver content, in accordance with experimental results.
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Myers, Kirby. "Experiments on the Thermal, Electrical, and Plasmonic Properties of Nanostructured Materials." Diss., Virginia Tech, 2018. http://hdl.handle.net/10919/83822.
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Nanofabrication techniques continue to advance and are rapidly becoming the primary route to enhancement for the electrical, thermal, and optical properties of materials. The work presented in this dissertation details fabrication and characterization techniques of thin films and nanoparticles for these purposes. The four primary areas of research presented here are thermoelectric enhancement through nanostructured thin films, an alternative frequency-domain thermoreflectance method for thin film thermal conductivity measurement, thermal rectification in nanodendritic porous silicon, and plasmonic enhancement in silver nanospheroids as a reverse photolithography technique.
Nanostructured thermoelectrics have been proposed to greatly increase thermopower efficiency and to bring thermoelectrics to mainstream power generation and cooling applications. In our work, thermoelectric thin films of SbTe, BiTe, and PbTe grown by atomic layer deposition and electrochemical atomic layer deposition were characterized for enhanced performance over corresponding bulk materials. Seebeck coefficient measurements were performed at temperatures ranging from 77 K to 380 K. Atomic composition was verified by energy-dispersive X-ray spectroscopy and structures were imaged by scanning electron microscopy. All thin films measured were ultimately found to have a comparable or smaller Seebeck coefficient to corresponding materials made by conventional techniques, likely due to issues with the growth process.
Frequency-domain thermoreflectance offers a minimally invasive optical pump-probe technique for measuring thermal conductivity. Like time-domain thermoreflectance, the version of frequency-domain thermoreflectance demonstrated here relies on a non-zero thermo-optic coefficient in the sample, but uses moderate cost continuous wave lasers modulated at kHz or MHz frequencies rather than a more expensive ultrafast laser system. The longer timescales of these frequency ranges enables this technique to take measurements of films with thicknesses ranging from 100 nm to 10 um, complimentary to time-domain thermoreflectance. This method differentiates itself from other frequency-domain methods in that it is also capable of simultaneous independent measurements of both the in plane and out of plane values of the thermal conductivity in anisotropic samples through relative reflective magnitude, rather than phase, measurements. We validated this alternate technique by measuring the thermal conductivity of Al2O3 and soda-lime and found agreement both with literature values and with separate measurements obtained with a conventional time-domain thermoreflectance setup.
Thermal rectification has the potential to enhance microcircuit performance, improve thermoelectric efficiency, and enable the creation of thermal logic circuits. Passive thermal rectification has been proposed to occur in geometrically asymmetric nanostructures when heat conduction is dominated by ballistic phonons. Here, nanodendritic structures with branch widths of ~ 10 nm and lengths of ~ 20 nm connected to ~ 50 um long trunks were electrochemically etched from <111> silicon wafers. Thermal rectification measurements were performed at temperatures ranging from 80 K to 250 K by symmetric thermal conductivity measurements. No thermal rectification was ultimately found in these samples within the margin of thermal conductivity measurement error 1%. This result is consistent with another study which found thermal rectification with greater conduction in the direction opposite to what ballistic phonon heat conduction theories predicted.
Plasmonic resonance concentrates incident photon energy and enables channeling of that energy into sub-wavelength volumes where it can be used for nanoscale applications. We demonstrated that surface plasmon polaritons induced in silver nanosphereoid films by 532 nm light defunctionalize previously photocleaved ligands adsorbed onto the films, to yield a reverse photolithographic technique. In this method, gold nanosphere conjugation were conjugated to a photocleaved ligand, however conjugation could be inhibited by exposing the cleaved ligand to 532 nm light and consequently yield a reversal technique. This defunctionalizion effect did not occur on gold films or nanoparticles conjugated with the ligand in IR spectroscopy, and was observed to have a reduced effect in silver films relative to silver nanospheroid film. As silver nanospheroid films and gold nanospheres of the size used in this study are known to have plasmon resonance in the green wavelengths, while gold and silver continuous films do not, this defunctionalization likely results from plasmonic effects.Ph. D.
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Khosravi, Khorashad Larousse. "Theoretical and Computational Study of Optical Properties of Complex Plasmonic Structures." Ohio University / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou150834414639462.
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Moeferdt, Matthias. "Nonlocal and Nonlinear Properties of Plasmonic Nanostructures Within the Hydrodynamic Drude Model." Doctoral thesis, Humboldt-Universität zu Berlin, 2017. http://dx.doi.org/10.18452/18129.
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In dieser Arbeit werden die nichtlokalen sowie nichtlinearen Eigenschaften plasmonischer Nanopartikel behandelt, wie sie im hydrodynamischen Modell enthalten sind. Das hydrodynamische Materialmodell stellt eine Erweiterung des Drude Modells dar, in der Korrekturen in der Beschreibung des Elektronenplasmas berücksichtigt werden. Einer ausführlichen Einführung des Materialmodells folgt eine analytische Diskussion der Auswirkungen der Nichtlokalität am Beispiel eines einzelnen Zylinders. Hierbei werden die durch die Nichtlokalität herbeigeführten Frequenzverschiebungen in den Streu- und Absorptionsspektren quantifiziert und asymptotisch behandelt. Des Weiteren wird mit Hilfe einer konformen Abbildung das Problem eines zylindrischen Dimers in der Elektrostatischen Näherung gelöst und die Moden der Struktur bestimmt. Diese Untersuchungen dienen als maßgebliche Grundlage für weiterführende numerische Studien die mit der diskontinuierlichen Galerkin Zeitraummethode durchgeführt werden. Die durch die analytischen Betrachtungen gewonnene Kenntnis der Moden ermöglicht es, im Zusammenhang mit gruppentheoretischen Betrachtungen und numerischen Untersuchungen, rigorose Auswahlregeln für die Anregung der Moden durch lineare und nichtlineare Prozesse aufzustellen. In weiterführenden numerischen Simulationen werden außerdem Strukturen niedrigerer Symmetrie, auf die sich die Auswahlregeln übertragen lassen, untersucht. Zudem werden numerische Studien präsentiert in denen der Einfluss der Nichtlokalität auf Feldüberhöhungen in Dimeren und doppel-resonantes Verhalten (es liegt sowohl bei der Frequenz des eingestrahlten Lichtes als auch bei der zweiten harmonischen eine Resonanz vor) untersucht werden.This thesis deals with the nonlocal and nonlinear properties of plasmonic nanoparticles, as described by the hydrodynamic model. The hydrodynamic material model represents an extension of the Drude model that contains corrections to the descriptions of the electron plasma. After a thorough derivation of the material model, analytical discussions of nonlocality are presented for the example of a single cylinder. The frequency shifts in the scattering and absorption spectra are quantified and treated asymptotically. Furthermore, by applying a conformal map, the problem of a cylindrical dimer is solved in the electrostatic limit and the modes of the structure are determined. These investigations lay the foundations for numerical investigations which are performed employing the discontinuous Galerkin time domain method. The analytical knowledge of the modes, in conjunction with group theoretical considerations and numerical analysis, enables the formulation of rigorous selection rules for the excitation of modes by linear and nonlinear processes. In further numerical studies, the influence of nonlocality on the field enhancement in dimer structures and double-resonant behavior (a resonance is found at the frequency of the incoming light and at the second harmonic) are investigated.
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Patoka, Piotr [Verfasser]. "Tunable plasmonic properties of nanostructures fabricated by shadow nanosphere lithography / Piotr Patoka." Berlin : Freie Universität Berlin, 2011. http://d-nb.info/102549024X/34.
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Near, Rachel Deanne. "Theoretical and experimental investigation of the plasmonic properties of noble metal nanoparticles." Diss., Georgia Institute of Technology, 2013. http://hdl.handle.net/1853/52181.
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Noble metal nanoparticles are of great interest due to their tunable optical and radiative properties. The specific wavelength of light at which the localized surface plasmon resonance occurs is dependent upon the shape, size and composition of the particle as well as the dielectric constant of the host medium. Thus, the optical properties of noble metal nanoparticles can be systematically tuned by altering these specific parameters. The purpose of this thesis is to investigate some of these properties related to metallic nanoparticles. The first several chapters focus on theoretical modeling to predict and explain various plasmonic properties of gold and silver nanoparticles while the later chapters focus on more accurately combining experimental and theoretical methods to explain the plasmonic properties of hollow gold nanoparticles of various shapes. The appendix contains a detailed description of the theoretical methods used throughout the thesis. It is intended to serve as a guide such that a user could carry out the various types of calculations discussed in this thesis simply by reading this appendix.
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Kravets, Vira V. "Optical Properties of Plasmonic Nanostructures for Bio-Imaging and Bio-Sensing Applications." Thesis, University of Colorado at Colorado Springs, 2017. http://pqdtopen.proquest.com/#viewpdf?dispub=10282081.
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Kravets, Vira V. (Ph.D., Physics) Optical properties of plasmonic nanostructures for bio-imaging and bio-sensing applications Dissertation directed by Associate Professor Anatoliy Pinchuk. ABSTRACT This dissertation explores the physics of free electron excitations in gold nanoparticle chains, silver nanoparticle colloids, and thin gold films. Electron excitations in nanostructures (surface plasmons, SP) are responsible for unique optical properties, which are applied in bio-sensing and bio-imaging applications. For gold nanoparticle chains, the effect of SP on resonance light absorption was studied experimentally and theoretically. Mainly, how the spectral position of the absorption peak depends on inter-particle distances. This dependence is used in ?molecular rulers?, providing spatial resolution below the Rayleigh limit. The underlying theory is based on particle interaction via scattered dipole fields. Often in literature only the near-field component of the scattered field is considered. Here, I show that middle and far fields should not be neglected for calculation of extinction by particle chains. In silver nanoparticles, SP excitations produce two independent effects: (a) the intrinsic fluorescence of the particles, and (b) the enhancement of a molecule?s fluorescence by a particle?s surface. The mechanism of (a) is deduced by studying how fluorescence depends on particle size. For (b), I show that fluorescence of a dye molecule on the surface of a nanoparticle is enhanced, when compared to that of the free-standing dye. I demonstrate that the dye?s fluorescent quantum yield is dependent on the particle?s size, making labeled silver nanoparticles attractive candidates as bio-imaging agents. Labeled nanoparticles are applied to cell imaging, and their bio-compatibility with two cell lines is evaluated here. Finally, in gold films under attenuated total internal reflection (ATR) conditions, the SP create a propagating wave (SP-polariton, SPP) when coupled with the incident light. Because of the sensitivity of SPPs to the medium adjacent to the gold film surface, they are widely applied in bio-sensing applications. A toolbox for the description of sputter-deposited gold films is presented here: it employs three experimental techniques (ATR, transmittance and atomic force microscopy) in combination with the effective medium theory for double-layered film model. Our findings have allowed for the avoidance of superficial fitting parameters in our model.
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Rose, Aaron Harold. "Emergent Properties of Plasmonic Systems in the Weak to Strong Coupling Regimes:." Thesis, Boston College, 2019. http://hdl.handle.net/2345/bc-ir:108654.
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Thesis advisor: Michael J. NaughtonIn this dissertation I present studies of plasmonic interactions in different coupling regimes, from zero to strong coupling and approaching ultrastrong coupling. Different physics are manifest in each regime, with different possible applications. The first project uses finite element electromagnetic simulations to model plasmonic waveguides that couple near field light into the far-field for sub-diffraction limited microscopy. Wavelength/32 resolution is shown by minimizing coupling between adjacent waveguiding nanowires, with minimal attenuation over a few microns. The next two projects, by contrast, seek to maximize coupling between plasmons and excitons into the strong coupling regime where the optoelectronic properties are modified and quantum coherent phenomena may be observed. Strong exciton–plasmon coupling in MoS2 is shown experimentally at room temperature and found to be a general phenomenon in other semiconducting transition metal dichalcogenides using transfer matrix modeling. A semiclassical oscillator model is fit to the experimental data to discover coherent hybridization between the ground and first excited states of MoS2. Enhanced coupling is found at the third excitonic transition, approaching the ultrastrong coupling regime where exotic properties are predicted to emerge, such as ground state virtual photons. Our strong coupling studies motivate further studies of the TMDCs as a platform for coherent quantum physics with possible applications in quantum computing and cryptography
Thesis (PhD) — Boston College, 2019
Submitted to: Boston College. Graduate School of Arts and Sciences
Discipline: Physics
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Hajimammadov, R. (Rashad). "Plasmonic, electrical and catalytic properties of one-dimensional copper nanowires:effect of native oxides." Doctoral thesis, Oulun yliopisto, 2018. http://urn.fi/urn:isbn:9789526218878.
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Abstract Recent advances in materials synthesis resulted in a rediscovery of the low cost copper in its one and two-dimensional forms and project newer applications of this metal in fields not considered before. In this thesis, one-dimensional copper, i.e. nanowires are synthesized by a hydrothermal route and explored for their chemical, electrical, catalytic and plasmonic properties with highlighted advantages, benefited from their size and shape compared to thin film and bulk copper. Characterization of copper nanowires and their native oxides were performed using a number of analytical techniques such as X-ray photoelectron and Auger spectroscopy, Raman spectroscopy, X-ray diffraction as well as scanning probe and electron microscopy techniques to elucidate the oxidation mechanism and to assess the feasibility of the oxidized materials for various applications. A few atomic layers of cuprous oxide seem to form on the surface of the nanowires instantly, maybe already during synthesis, which then slowly grows further when exposing the nanowires to ambient air leading to the appearance of cupric oxide as well. Because of the surface oxides, individual nanowires and their bundled networks exhibit semiconducting behavior, which complicates the direct use of such materials for interconnections in electronics. However, even with the presence of native oxides, copper nanowires hold promise in many other applications such as the ones explored here for plasmonics and heterogeneous catalysis. As demonstrated in this work, surface plasmon absorption properties of the nanowires can be exploited for chemical sensing of surface adsorbed molecules (model compound Rhodamine 6G) by efficiently amplifying its Raman spectrum without using any lithographically defined sensor template. Further, it is shown that phenol contamination in water may be efficiently eliminated by converting it to nontoxic polyphenol as well as to CO2 owing to the highly efficient catalytic property of the mixed oxide phases on the surface of the nanowires. The results published in this thesis contribute to the understanding of the chemical and physical behavior of copper nanowires and other low dimensional copper nanostructures that undergo rapid surface oxidationTiivistelmä Jatkuva elektronisten laitteiden ja anturien pienentäminen on hyvin linjassa teknologian kehittymisen kanssa. Pyrkimys monitoimisiin ja tehokkaisiin materiaaleihin on muuttanut tavanomaisten materiaalien käsitystä. Viimeisimmät edistysaskeleet materiaalisynteesissä ovat johtaneet edullisen kuparin uudelleenlöytämiseen sen yksi- ja kaksidimensionaalisissa muodoissa ennustaen metallille uusia sovellutuksia alueilla, joissa sitä ei ole aiemmin hyödynnetty. Tässä väitöstyössä on tutkittu hydrotermisesti syntetisoitujen yksiulotteisten kuparinanojohtimien kemiallisia, sähköisiä, katalyyttisiä ja plasmonisia ominaisuuksia sekä näiden pieneen kokoon ja muotoon perustuvia etuoja ohutkalvo- ja bulkkikupariin verrattuna. Kuparinanojohtimia ja niiden luonnollisia oksideja karakterisoitiin useilla analyysitekniikoilla kuten röntgenelektroni- ja Auger-eletronispektroskopialla, Raman-spektroskopialla, röntgendiffraktiolla sekä pyyhkäisykärki- ja elektronimikroskopialla selvittäen hapettumismekanismeja ja oksidien soveltuvuutta eri käyttötarkoituksiin. Muutaman atomikerroksen paksuinen kupari(I)oksidikerros havaittiin muodostuvan välittömästi, luultavasti jo materiaalisynteesin aikana nanojohtimien pinnalle. Nanojohtimien altistuessa ympäröivälle ilmalle oksidikerros kehittyi hitaasti johtaen kupari(II)oksidin muodostumiseen. Pintaoksidien johdosta yksittäiset nanojohtimet ja niistä yhteenkasautuneet verkostot käyttäytyvät puolijohdemaisesti mikä monimutkaistaa näiden materiaalien käyttöä sellaisenaan elektroniikan johtimissa. Luonnollisista oksideista huolimatta kuparinanojohtimet ovat lupaavia monissa muissa sovelluksissa, kuten tässä työssä tutkituissa plasmonisessa ja heterogeenisessä katalyysissä. Väitöstyössä osoitetaan, että nanojohtimen pintaplasmonisia absorptio-ominaisuuksia voidaan hyödyntää pintaan absorboituneiden molekyylien kemiallisessa havainnoinnissa (mallinnettu yhdiste rodamiini 6G) vahvistamalla Raman–spektriä käyttämättä lainkaan litografiapohjaista anturisapluunaa. Myöskin vesien fenolikontaminaatio voidaan tehokkaasti muuntaa myrkyttömiksi polyfenoleiksi ja hiiidioksidiksi hyödyntämällä nanojohtimien pinnalla olevia oksideja tehokkaana katalyyttinä (jopa parempi kuin kaupallisten kupariin pohjautuvat katalyytit). Tässä väitöstyössä julkaistut tulokset edistävät kuparinanojohtimien sekä muiden pienikokoisten ja nopeasti hapettuvien kuparinanorakenteiden kemiallisen ja fyysisen käytöksen ymmärtämistä. Tieteellisten kehitysaskeleiden lisäksi tämä väitöstyö voi myös toimia lähteenä pienirakenteisten yleisten metallien sovelluksille
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Jeannin, Mathieu Emmanuel. "Control of the emission properties of semiconducting nanowire quantum dots using plasmonic nanoantennas." Thesis, Université Grenoble Alpes (ComUE), 2016. http://www.theses.fr/2016GREAY053/document.
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Ce travail de thèse porte sur l'étude du couplage entre des boîtes quantiques (BQs) insérées dans des nanofils à semiconducteurs et des antennes plasmoniques. Un couplage efficace requiert une caractérisation complète des leurs propriétés optiques respectives, pour assurer un recouvrement spectral et spatial de l'émission de la boîte et du mode de l'antenne et l'alignement de la polarisation du mode plasmonique avec l'émission de la BQ.Les propriétés optiques d'antennes patchs plasmoniques circulaires ont été étudiées par cathodoluminescence (CL). Nous avons montré avec un modèle analytique de la densité locale d'états électromagnétiques (DLE) au voisinage des antennes que leurs résonances sont des superpositions de modes de Bessel d'ordre radiaux et azimutaux différents. Nous avons fabriqué et caractérisé des antennes mono et multimodes, et trouvé que la partie radiative de la DLE n'est pas la seule contribution au signal de CL. De plus, nous avons caractérisé des antennes de différentes épaisseur du plan diélectrique ou différents matériaux. L'analyse de ces résultats nous pousse à proposer une interprétation des contributions au signal de CL annexes à la partie radiative de la DLE supportée par l'antenne. Nous avons de plus démontré la fabrication d'antennes patchs en aluminium opérant dans la partie bleue du spectre électromagnétique, et appliqué la CL à d'autres géométries d'antennes.Nous avons également étudié différentes boîtes quantiques insérées dans des nanofils à semiconducteurs faits d'alliages de matériaux II-VI. Des émetteurs uniques sont étudiés par microphotoluminescence (µPL). Des mesures résolues en temps ou par microscopie de Fourier permettent une caractérisation spectrale, temporelle et la détermination de leur diagramme de rayonnement. Nous avons de plus mis en évidence les variations de propriétés optiques des émetteurs dues aux inhomogénéité de fabrication en étudiant un large ensemble de BQs. La modélisation complète des propriétés électroniques et optiques d'une boîte unique est proposée en utilisant la microscopie de Fourier résolue en polarisation, et une étape de spectroscopie magnéto-optique.Enfin, nous avons développé une méthode de lithographie électronique en deux étapes basée sur le repérage d'un émetteur unique par CL, permettant la fabrication d'antennes plasmoniques couplées de façon déterministe à des BQs insérées dans des nanofils. L'étude de ce couplage révèle un accroissement de l'absorption du faisceau d'excitation accompagné d'une accélération de l'émission de la boîte par couplage radiatif. Il en résulte une exaltation jusqu'à un facteur 2 de la µPL des boîtesIn this work, we study the coupling between plasmonic nanoantennas and semiconducting nanowire quantum dots (NWQDs). This coupling requires spectral, spatial and polarisation matching of the antenna mode and of the NWQD emission. Hence, a full characterisation of both the antenna system and the NWQDs has to be performed to determine a relevant coupling geometry.Using cathodoluminescence (CL) we investigate the relation between the CL signal of circular patch plasmonic antennas and the electromagnetic local density of states (LDOS). The successive resonances supported by these antennas are complex superimpositions of Bessel modes of different radial and azimuthal order. Applying an analytical LDOS model, we show that we can fabricate and characterise antennas down to single mode resonances. However, the antennas CL spectrum goes beyond the radiative part of the LDOS. By changing the spacing layer thickness and the antennas materials, we propose an explanation for the origin of the additional CL signal we observe that is not related to the radiative LDOS of the patch antennas. We also demonstrate the fabrication of Al patch antennas working in the blue spectral range and apply our method to other geometries.We perform optical characterisation of different quantum dots (QDs) embedded inside semiconducting nanowires (NWs) made of II-VI materials. We use microphotoluminescence (µPL) to study the emission of single NWQDs. Time-resolved measurements and Fourier imaging allows us to extract their exciton lifetime and radiation patterns. The variability in the emission properties of the NWQDs due to inhomogeneity in the growth process are evidenced by studying a statistical set of nanowires. A complete model based on polarisation-resolved Fourier imaging and magneto-optical spectroscopy is detailed, allowing to fully determine the QD electronic and optical properties for an individual system.Finally, we develop a cathodoluminescence-based two-step electron-beam lithography technique to deterministically fabricate plasmonic antennas coupled to NWQDs, enhancing their µPL properties. The coupling results in an enhanced absorption of the pump laser inside the NW and in an increase of the radiative rate of the QD, leading to up to a two-fold intensity enhancement factor for the coupled system
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Funes-Hernando, Daniel. "Advanced gold-based nanowires : from hybrid structures to original plasmonic and optical properties." Thesis, Nantes, 2018. http://www.theses.fr/2018NANT4076/document.
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La plasmonique exploite les plasmons polaritons de surface (SPP) et les plasmons de surface localisés (LSP). Les nanostructures 1D métalliques et hybrides ouvrent la voie à l’exploitation combinée de la nature de propagation du SPP et du caractère émissif des LSPR. Durant ma thèse, j'ai conçu des nanofils fonctionnels à base d'or pour l'exploration et l'exploitation de ces propriétés. Un résultat important concerne la conception de nanofils coaxiaux pour permettre la détection de signaux Raman à distance. La spectroscopie Raman à distance repose sur la séparation de plusieurs micromètres de l’excitation par un laser à une extrémité du nanofil et de la détection Raman à l’autre extrémité. La très faible efficacité de l'émission Raman est un défi supplémentaire. Des nanofils coaxiaux constitués d'un coeur d'or, pour propager les SPP, et d'une gaine de poly(3,4-éthylène-dioxythiophène) pour le signal Raman ont été conçus pour la preuve de concept. Cette étude a permis de mettre en évidence une forte orientation préférentielle des chaînes de polymères attribuée à la synthèse ultraconfinée. Dans une autre étude, nous avons cherché à améliorer le comportement d’antenne de ces nanofils. Pour cela, un traitement laser post-synthèse a permis de produire des protubérances aux extrémités des nanofils d’or. Il en résulte un couplage plus efficace avec la lumière incidente pour exciter les SPP et une augmentation de la lumière diffusée à l'extrémité opposée. Ces études constituent des approches alternatives pour la détection à distance de substances photodégradables et pour l'exploration de nanosources 1D et nano-antennes pour des systèmes photoniques et plasmoniques intégrésPlasmonics is an important research topic for nanophotonics based on surface plasmon polaritons (SPP) and localized surface plasmons (LSP). 1D-like metallic and hybrid nanostructures opens the way to exploit altogether the propagative nature of SPP in a guided way, and the strong field enhancement of LSPR. During my thesis work, I designed functional gold-based nanowires with controlled morphological and compositional characteristics for exploring and exploiting their plasmonic properties. A main achievement reports on the plasmon-mediated remote Raman sensing promoted by coaxial nanowires. Remote Raman spectroscopy is based on the separation by many micrometres of the excitation laser spot on one tip of the nanowire, and the Raman detection at the other tip. The very weak efficiency of Raman emission makes it challenging. Coaxial nanowires consisting of a gold core to propagate SPP and a Raman-emitting shell of poly(3,4-ethylene-dioxythiophene) were synthesized for the proof-of-concept. This study also permits to evidence a strong preferential orientation of the polymer chains due to the ultra-confined synthesis. In another study, the enhancement of both the SPP excitation and the light emission efficiency has been realized by transforming the gold nanowire tips with optimized laser treatments. It results in dog bones like nanowires, which improve the coupling with the excitation light for a suitable polarization and increase the scattered light at the opposite tip. These studies constitute alternative approaches for the remote detection of photo-degradable species and for exploring 1D nanosources and nanoantennae for integrated photonic and plasmonic systems
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Dienerowitz, Maria. "Plasmonic effects upon optical trapping of metal nanoparticles." Thesis, University of St Andrews, 2010. http://hdl.handle.net/10023/1634.
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Optical trapping of metal nanoparticles investigates phenomena at the interface of plasmonics and optical micromanipulation. This thesis combines ideas of optical properties of metals originating from solid state physics with force mechanism resulting from optical trapping. We explore the influence of the particle plasmon resonance of gold and silver nanospheres on their trapping properties. We aspire to predict the force mechanisms of resonant metal particles with sizes in the Mie regime, beyond the Rayleigh limit. Optical trapping of metal nanoparticles is still considered difficult, yet it provides an excellent tool to investigate their plasmonic properties away from any interface and offers opportunities to investigate interaction processes between light and nanoparticles. Due to their intrinsic plasmon resonance, metal nanoparticles show intriguing optical responses upon interaction with laser light. These differ greatly from the well-known bulk properties of the same material. A given metal nanoparticle may either be attracted or repelled by laser light, only depending on the wavelength of the latter. The optical forces acting on the particle depend directly on its polarisability and scattering cross section. These parameters vary drastically around the plasmon resonance and thus not only change the magnitude but also the direction and entire nature of the acting forces. We distinguish between red-detuned and blue-detuned trapping, that is using a trapping wavelength shorter or longer than the plasmon resonance of the particle. So far optical trapping of metal nanoparticles has focussed on a wavelength regime far from the particle’s resonance in the infrared. We experiment with laser wavelengths close to the plasmon resonance and expand the knowledge of metal nanoparticle trapping available to date. Existing theoretical models are put to the test when we compare these with our real experimental situations.
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Walter, Felicitas [Verfasser]. "Optical properties and encoding of information of nonlinear and active plasmonic metasurfaces / Felicitas Walter." Paderborn : Universitätsbibliothek, 2018. http://d-nb.info/1171897685/34.
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MOHAMMED, AHMED ALSADIG AHMED. "Harnessing the plasmonic properties of gold nanoparticles: functionalization strategies coupled with novel spectroscopic tools." Doctoral thesis, Università degli Studi di Trieste, 2022. http://hdl.handle.net/11368/3030486.
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Metallic plasmonic substrates such as gold nanoparticles (AuNPs) have fascinated researchers due to their usefulness in verious interdisciplinary studies at the interface between applied physics, biochemistry, engineering, and medicine. A good understanding of the physics of these noble nanostructures, particularly the plasmonic and optical properties, can be employed to improve a
wide range of sensors and electronic devices. The relevance of molecular recognition and the binding of biological and chemical entities to diagnostics, biosensors, and drug delivery has attracted significant research interest. By addressing material functionalization design and advanced characterization methods, this doctoral work aims to highlight efforts to exploit the surface modification strategies to enhance the responsiveness of nanoparticle substrates for improved detection of health-relevant biomolecules. The self-assembly of small ligands, such as alkanethiols, and oligonucleotides on the surface of AuNPs provided a possible starting route for the preparation of bio-nanomaterials with precise physicochemical properties. The versatile AuNPs were optimized and thoroughly characterized by employing electron microscopy techniques such as transmission electron microscope (TEM), atomic force microscopy (AFM), and scanning electron microscopy (SEM), spectroscopic techniques, including ultraviolet/visible (UV/Vis), dynamic light scattering (DLS), and thermal lens spectrometry (TLS), and biochemical assays (gel electrophoresis, Dot plot, Western plot, and the Enzyme Linked Immunosorbent Assay (ELISA)). Subsequently, the molecular recognition capabilities of functionalized AuNPs were investigated using multiple techniques, including novel detection routes such as the electrophoresis approach coupled with online TLS. This work establishes a versatile platform for AuNP engineering with controlled size and surface functionality. The strategies presented in this thesis aim to improve medical diagnostics to make them affordable for point-of-care scenarios to enhance the quality of human health.wide range of sensors and electronic devices. The relevance of molecular recognition and the binding of biological and chemical entities to diagnostics, biosensors, and drug delivery has attracted significant research interest. By addressing material functionalization design and advanced characterization methods, this doctoral work aims to highlight efforts to exploit the surface modification strategies to enhance the responsiveness of nanoparticle substrates for improved detection of health-relevant biomolecules. The self-assembly of small ligands, such as alkanethiols and oligonucleotides on the surface of AuNPs provided a possible starting route for the preparation of bio-nanomaterials with precise physicochemical properties. The versatile AuNPs were optimized and thoroughly characterized by employing electron microscopy techniques such as transmission electron microscope (TEM), atomic force microscopy (AFM), and scanning electron microscopy (SEM), spectroscopic techniques, including ultraviolet/visible (UV/Vis), dynamic light scattering (DLS), and thermal lens spectrometry (TLS), and biochemical assays (gel electrophoresis, Dot plot, Western plot, and the Enzyme Linked Immunosorbent Assay (ELISA)). Subsequently, the molecular recognition capabilities of functionalized AuNPs were investigated using multiple techniques, including novel detection routes such as the electrophoresis approach coupled with online TLS. This work establishes a versatile platform for AuNP engineering with controlled size and surface functionality. The strategies presented in this thesis aim to improve medical diagnostics to make them affordable for point-of-care scenarios to enhance the quality of human health.
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Baral, Susil. "Fundamental Studies of Photothermal Properties of a Nanosystem and the Surrounding Medium Using Er3+ Photoluminescence Nanothermometry." Ohio University / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1493301965290212.
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Amooali, Khosroabadi Akram. "Optical and Electrical Properties of Composite Nanostructured Materials." Diss., The University of Arizona, 2014. http://hdl.handle.net/10150/333480.
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A novel lithographic fabrication method is used to fabricate nanopillars arrays of anisotropic Ag and TCO electrodes. Optical and electrical properties of the electrodes including bandgap, free carrier concentration, resistivity and surface plasmon frequency of different electrodes can be tuned by adjusting the dimensions and geometry of the pillars. Given the ability to tune the nonlocal responses of the plasmonic field enhancements, we attempt to determine the nature of the effective refractive index profile within the visible wavelength region for multi-layer hybrid nanostructures. Knowledge of the effective optical constants of the obtained structure is critical for various applications. nanopillars of TCO\Ag core shell structures have been successfully fabricated. The Maxwell-Garnett mixing law has been used to determine the optical constants of the nanostructure based on spectroscopic ellipsometry measurements. Simulated reflection spectra indicate a down shift in the Brewster angle of the pillars resulting from the reduction in the effective refractive index of the nanostructure. Two plasmonic resonances were observed, with one in the visible region and the other in the IR region. Plasmon hybridization model is used to describe the behavior of metal and metal oxide core shell nanostructured electrodes. Different charge density distributions around the pillars determine the plasma frequency which depends on the core and surrounding media dielectric constants. Finite Difference Time Domain (FDTD) simulation of different structures agree well with experiment and help us to understand electric field behavior at different structures with different geometries and dielectric constants. Plasmonic Ag nanopillar arrays are effective substrates for surface enhanced Raman spectroscopy (SERS). An enhancement factor up to 6 orders of magnitude is obtained. Monolayers of C60 is deposited on the Ag nanopillars and the interface of C60/Ag is studied which is important in optoelectronic devices. Electron delocalization between C60 and Ag is confirmed.
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Tanyeli, Irem. "Effect Of Substrate Type On Structural And Optical Properties Of Metal Nanoparticles For Plasmonic Applications." Master's thesis, METU, 2011. http://etd.lib.metu.edu.tr/upload/12613563/index.pdf.
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In this work, the structural and optical properties of metal nanoparticles fabricated on various substrates have been investigated. The particles were fabricated by electron beam lithography (EBL) and dewetting of a thin metal film. The advantages and disadvantages of these two fabrication techniques are discussed by considering the properties of the nanoparticles and the applicability to large area substrates. Being a practical fabrication method, dewetting can be applied to any substrate with either small or large surfaces. For comparison between different sample types, some process parameters such as film thickness, annealing temperature and duration were fixed during the whole study. Gold (Au) and silver (Ag) were preferred for nanoparticle formation because of their superior optical properties for solar cell applications. We used silicon (Si), silicon nitride (Si3N4), silicon dioxide (SiO2) and indium tin oxide (ITO) on glass, and textured Si as the substrate for the particle formation. These substrates are commonly used in solar cell technology for different purposes. The formation of the metal nanoparticles, their size and size distribution were monitored by Scanning Electron Microscope (SEM). We performed a dimension analysis on the SEM images using a program called Gwyddion. We observed that the substrate type greatly affects particle mean size, suggesting a dependence of the dewetting process on the interface properties. Moreover, the effect of the annealing temperature was found to be a function of the substrate type.
Scattering measurements have been carried out in order to observe the localized surface plasmon resonance (LSPR) conditions. The effect of the particle size and the dielectric environment was observed as a shift in the plasmon resonance peak position along the wavelength axis. As expected from the theory, the resonance peaks shift to longer wavelengths with increasing particle size and dielectric constant. In order to compare the experimental results with the theory, Mie theory was applied to calculate the plasmon resonance peaks. We obtained fairly well agreement between the experimental and theoretical results. In this study, nanoparticles were assumed to be in contact with more than one medium, namely air and the underlying substrate.
Finally, we have reached a successful methodology and knowledge accumulation for the metal particle formation on variety of substrates by the dewetting technique. It is clear that this knowledge can form basis for the photovoltaic applications.
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Alber, Ina [Verfasser], and Reinhard [Akademischer Betreuer] Neumann. "Synthesis and Plasmonic Properties of Metallic Nanowires and Nanowire Dimers / Ina Alber ; Betreuer: Reinhard Neumann." Heidelberg : Universitätsbibliothek Heidelberg, 2012. http://d-nb.info/1177039982/34.
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Bordley, Justin Andrew. "Cubic architectures on the nanoscale: The plasmonic properties of silver or gold dimers and the catalytic properties of platinum-silver alloys." Diss., Georgia Institute of Technology, 2016. http://hdl.handle.net/1853/55025.
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This thesis explores both the optical and catalytic properties of cubic shaped nanoparticles. The investigation begins with the sensing capabilities of cubic metal dimers. Of all the plasmonic solid nanoparticles, single Ag or Au nanocubes exhibit the strongest electromagnetic fields. When two nanoparticles are in close proximity to each other the formation of hot spots between plasmonic nanoparticles is known to greatly enhance these electromagnetic fields even further. The sensitivity of these electromagnetic fields as well as the sensitivity of the plasmonic extinction properties is important to the development of plasmonic sensing. However, an investigation of the electromagnetic fields and the corresponding sensing capabilities of cubic shaped dimers are currently lacking.
In Chapters 2-5 the optical properties of cubic dimers made of either silver or gold are examined as a function of separation distance, surrounding environment, and dimer orientation. A detailed DDA simulation of Au–Au and Ag-Ag dimers oriented in a face-to-face configuration is conducted in Chapter 2. In this Chapter a distance dependent competition between two locations for hot spot formation is observed. The effect of this competition on the sensing capabilities of these dimers is further explored in Chapters 3 and 4. This competition originates from the generation of two different plasmonic modes. Each mode is defined by a unique electromagnetic field distribution between the adjacent nanocubes.
In Chapter 4 the maximum value of the electromagnetic field intensity is investigated for each mode. Notably the magnitude of the electromagnetic field is not directly proportional to its extinction intensity. Furthermore, the sensitivity of a plasmonic mode does not depend on its extinction intensity. The sensitivity is rather a function of the magnitude of the electromagnetic field intensity distribution. Also, the presence of a high refractive index substrate drastically affects the optical properties and subsequent sentivity of the dimer. In Chapter 5 the sensing properties of a cubic dimer is investigated as a function of orientation. As the separation distance of the nanocube dimer is decreased the orientation of the dimer drastically affects its coupling behavior. The expected dipole-dipole exponential coupling behavior of the dimer is found to fail at a separation distance of 14 nm for the edge-to-edge arrangement. The failure of the dipole-dipole coupling mechanism results from an increased contribution from the higher order multipoles (eg. quadrupole-dipole). This behavior begins at a separation distance of 6 nm for the face-to-face dimer. As a result, the relative ratio of the multipole to the dipole moment generated by the edge-to-edge dimer must be larger than the ratio for the face-to-face orientation.
In the last section of this thesis the catalytic properties of cubic nanoparticles composed of a platinum-silver alloy are investigated. The catalytic activity and selectivity towards a given reaction is intimately related to the physical and electronic structure of the catalyst. These cubic platinum-silver alloys are utilized as catalysts for the oxygen reduction reaction (ORR). A maximum enhancement in the specific activity (3.5 times greater than pure platinum) towards the ORR is observed for the cubic platinum-silver alloy with the lowest platinum content. This activity is investigated as a function of the physical structure of a cubic shaped catalyst as well as the electronic modifications induced by the formation of a platinum-silver alloy.
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Babocký, Jiří. "Optické vlastnosti asymetrických plasmonických struktur." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2014. http://www.nusl.cz/ntk/nusl-231373.
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This diploma thesis deals with study of resonance modes of plasmonic structures. First part provides an overview of theoretical models, which explain the resonanace modes in plasmonic structures. Next part describes technology of electron beam lithography. First section of experimental part deas with technological processes leading to an improvement of resulting structures made by electron beam lithography that is followed by lift-off process. Last part focuses on a study of reflectance spactra of plasmonic antenas and the identification of resonance modes.
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Liyanage, Dilhara. "Efficient Integration of Plasmonic and Excitonic Properties of Metal and Semiconductor Nanostructures via Sol-Gel Assembly." VCU Scholars Compass, 2017. http://scholarscompass.vcu.edu/etd/4768.
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Research in nanoscience has gained noteworthy interest over the past three decades. As novel chemical and physical properties that are vastly different from extended solids are realized in nanosized materials, nanotechnology has become the center of attention for material in research community. Much to our amazement, investigations in the past two decades revealed that the nanocrystalline semiconductors are “THE PRIME CANDIDATES” to meet the growing energy demand, sensor development, cellular imaging and a number of other optoelectronic applications. Nonetheless, synthesis of nanostructures with control over physical parameters is not sufficient, yet assembling them into functional nanoarchitectures with unique and tunable physical properties is critical for device integration studies. Among bottom-up assembling methods, sol-gel method has received noteworthy interest to produce macroscopic nanostructures of metal and semiconductor NPs with no use of intervening ligands or supports.
In 2005, condensation of pre-formed semiconductor NPs (CdSe, CdS, ZnS and PbS) into voluminous gels is reported via controlled destabilization of the surfactant ligands. The resultant chalcogenide aerogels are reported to exhibit extremely low density, high surface area and porosity, and quantum confined optical properties of the NP building blocks. More recently, this method has been extended for the assembly of metal NPs, where transparent and opaque nanostructures (aerogels) of Ag and Au/Ag NPs were produced. The aerogels produced by condensation of NPs are low dimensional (fractal) nanostructures and exhibit a physically connected network of colloidal NPs. Interactions between NPs in a gel structure are intermediate of those of the ligand stabilized NPs and core/shell hetero-nanostructures (e.g. Au@CdSe NPs) with the potential to couple chemically dissimilar systems. In this research study, NP condensation strategy has been utilized to efficiently integrate the plasmonic and excitonic properties of metal and semiconductor nanostructures to produce high-efficiency hybrids that exhibit unique tunable physical and photophysical properties.
Two hybrid systems composed of spherical CdSe/Ag hollow NPs and rod shaped CdSe/Ag hollow NPs were investigated for the fabrication of metal-semiconductor hybrid aerogels. The first excitonic energy of spherical CdSe NPs is overlapped with the plasmonic energy of Ag hollow NPs at 515 - 530 nm. The second excitonic energy of rod shaped CdSe is overlapped with the plasmonic energy of Ag hollow NPs at 490 - 505 nm. The photophysical properties of both systems were thoroughly probed through UV-Visible absorption, photoluminescence (PL), and time-resolved (TR) PL spectroscopy. A novel hybrid emission emerged at 640 nm (for spherical CdSe/Ag hollow NPs) and 720 nm (for rod shaped CdSe/Ag hollow NPs) with ~0.2-1% Ag loading. TRPL studies revealed 685 ns and 689 ns PL decay times for hybrid emissions, which are vastly different from the band-edge and trap state emission of phase pure spherical and rod shaped CdSe aerogels respectively, supporting the generation of novel radiative decay pathways. Overall, synthesis of CdSe/Ag hybrid aerogels with novel/tunable photophysical properties will add to the toolbox of semiconductor aerogels with the potential application in future light harvesting technologies.
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Selvanathan, Pramila. "Photochromic switches for luminescence, plasmonic resonance, single molecule magnetic properties, and molecular wires for nano junctions." Thesis, Rennes 1, 2016. http://www.theses.fr/2016REN1S145.
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Ce travail est consacré à la synthèse et la caractérisation des commutateurs et des fils moléculaires incorporant l'unité et le ruthénium organométalliques fractions photochromiques. La première partie traite de lanthanides complexe Yb combiné avec l'unité et le ruthénium acétylure fractions photochromiques afin de moduler la luminescence avec l'aide de redox et de stimuli lumineux. Dans la deuxième partie explique la combinaison d'unités DTE photochromiques avec des fragments acétylures de ruthénium pour fixer sur la surface de nanoparticules métalliques afin d'affiner leur résonance plasmonique grâce à la modification de l'environnement de surface en utilisant la lumière et redox stimuli. La troisième partie décrit la préparation de complexes de lanthanides combinés avec une unité photochromique spiropyranne pour commuter les propriétés SMM des complexes via photoisomérisation de l'unité spiropyranne. Dans la dernière partie, nous présentons la synthèse de Oligo (phénylène éthylène) Les fils moléculaires avec différents noyaux centraux afin d'obtenir une variété de fil avec différents niveaux d'énergie HOMO-LUMO pour vérifier l'effet de l'épinglageThis work is devoted to the synthesis and characterization of novel molecular switches and wires incorporating photochromic unit and ruthenium organometallic moieties. The first part deals with lanthanide Yb complex combined with photochromic unit and ruthenium acetylide moieties in order to modulate the luminescence with the help of redox and light stimuli. In the second part explained the combination of photochromic DTE units with ruthenium acetylide moieties to attach on the surface of metal nanoparticles in order to tune their plasmonic resonance through the surface environment modification by using light and redox stimuli. The third part describes the preparation of lanthanide complexes combined with a spiropyran photochromic unit in order to switch the SMM properties of the complexes via photoisomerization of the spiropyran unit. In the last part, we report the synthesis of Oligo(phenylene ethylene) molecular wires with different central cores in order to obtain various wire with different HOMO-LUMO energy levels to check the effect of pinning
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De, Silva Vashista C. "Core-Shell Based Metamaterials: Fabrication Protocol and Optical Properties." Thesis, University of North Texas, 2017. https://digital.library.unt.edu/ark:/67531/metadc1062904/.
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The objective of this study is to examine core-shell type plasmonic metamaterials aimed at the development of materials with unique electromagnetic properties. The building blocks of metamaterials under study consist of gold as a metal component, and silica and precipitated calcium carbonate (PCC) as the dielectric media. The results of this study demonstrate important applications of the core-shells including scattering suppression, airborne obscurants made of fractal gold shells, photomodification of the fractal structure providing windows of transparency, and plasmonics core-shell with a gain shell as an active device. Plasmonic resonances of the metallic shells depend on their nanostructure and geometry of the core, which can be optimized for the broadband extinction. Significant extinction from the visible to mid-infrared makes fractal shells very attractive as bandpass filters and aerosolized obscurants. In contrast to the planar fractal films, where the absorption and reflection equally contribute to the extinction, the shells' extinction is caused mainly by the absorption. This work shows that the Mie scattering resonance of a silica core with 780 nm diameter at 560 nm is suppressed by 75% and only partially substituted by the absorption in the shell so that the total transmission is noticeably increased. Effective medium theory supports our experiments and indicates that light goes mostly through the epsilon-near-zero shell with approximately wavelength independent absorption rate. Broadband extinction in fractal shells allows as well for a laser photoburning of holes in the extinction spectra and consequently windows of transparency in a controlled manner. Au fractal nanostructures grown on PCC flakes provide the highest mass normalized extinction, up to 3 m^2/g, which has been demonstrated in the broad spectral range. In the nanoplasmonic field active devices consist of a Au nanoparticle that acts as a cavity and the dye molecules attached to it via thin silica shell as the active medium. Such kind of devices is considered as a nano-laser or nano-amplifier. The fabricated nanolasers were studied for their photoluminescence kinetic properties. It is shown that the cooperative effects due to the coupling of dye molecules via Au nanoparticle plasmons result in bi-exponential emission decay characteristics in accord with theory predictions. These bi-exponential decays involve a fast superradiant decay, which is followed by a slow subradiant decay. To summarize, this work shows new attractive properties of core-shell nanoparticles. Fractal Au shells on silica cores prove to be a good scattering suppressor and a band pass filter in a broadband spectral range. They can also be used as an obscurant when PCC is used as the core material. Finally, gold nanoparticles coated with silica with dye results in bi-exponential decays.
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Stockhausen, Verena. "Modulation of material properties using Nanoelectrochemistry : from active plasmonic devices and photovoltaic systems to ultrathin electroactive layers." Paris 7, 2011. http://www.theses.fr/2011PA077071.
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L'essor de l'électronique plastique a conduit à une révolution dans la vie quotidienne ces vingt dernières années. Le premier chapitre traite des systèmes hybrides polymères conducteurs/dispositifs plasmoniques. La commutation de l'état électronique du polymère modifie réversiblement les réponses optiques des systèmes plasmoniques. De plus, en jouant sur la nature du polymère, la réponse optique de ces systèmes peut être finement ajustée. Dans le deuxième chapitre, nous aborderons l'étude des films ultraminces électroactifs générés par electroréduction d'un sel de diazonium. Premièrement, le greffage de tels films sans unité centrale benzénique sera développé. Deuxièmement, nous étudierons l'influence du dérivé thiophène attaché à l'unité centrale benzénique, d'une part sur le processus de formation des diazoniums et d'autre part sur les propriétés des films greffés. Le troisième chapitre concerne la fonctionnalisation de surface dite «bottom-up» en surgrefFant des composés monomériques sur les oligomères préalablement déposés. Ceci induit une modification des propriétés du film selon le monomère utilisé et augmente les possibilités de design de films minces électroactifs. Enfin, le quatrième chapitre traitera des cellules photovoltaïques de type Grätzel. Le but étant de fabriquer des cellules photovoltaïques plasmoniques afin d'améliorer les performances du système initial. Les processus de fabrication et la nature de la navette rédox sont d'abord optimisés. Ensuite, plusieurs stratégies pour la déposition de l'or ainsi que les premiers tests d'incorporation seront présentésOver the last twenty years, a continuous increase in plastic electronics has lead to a revolution in lifestyle. In the first chapter, we will discuss hybrid conducting polymer/plasmonic nanoparticle Systems and demonstrate that optical answers of plasmonic structures can not only be reversibly switched according to conducting polymer electronic state. Furthermore, the polymer type induces distinct optical answers, offering tremendous possibilities for further tailoring of optical properties. The second chapter is dedicated to ultrathin electroactive film generation from diazonium salt electroreduction. The first part presents successful diazonium salt derived film deposition without core benzene unit. The second part is devoted to the influence of the thiophene derivative, attached to the core benzene, on diazonium salt generation and electronic properties of gratted films. The third chapter demonstrates that a bottom-up approach can be used to further elongate oligomer chains by overgrafting monomeric compounds. By that, film properties are modified according to the monomer used, enlarging possibilities of distinct electroactive thin film design. In the fourth chapter, we investigate dye sensitized solar cells (DSSC) or Grätzel type cells with regard to the establishment of low cost plasmonic DSSC. By that, we hope to increase efficiencies of the basic System. In a first time, cell setup will be optimized to allow comparison with literature and then, the redox mediator will be replaced in order to optimize the System for subsequent gold incorporation. Finally, several strategies for gold deposition and first tests in cell setup will be demonstrated
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Wickremasinghe, Niranjala D. "Optical Properties of Organic Films, Multilayers and Plasmonic Metal-organic Waveguides Fabricated by Organic Molecular Beam Deposition." University of Cincinnati / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1439307144.
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Wang, Wei. "Plasmonic properties of subwavelength structures and plasmonic optical devices." Thesis, 2009. http://hdl.handle.net/2152/ETD-UT-2009-08-303.
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This thesis proposes a metallic hole array of a rectangular converging-diverging channel (RCDC) shape with extraordinary transmission. We use a three-dimensional (3D) finite element method to analyze the transmission characteristics of two-dimensional metallic hole arrays (2D-MHA) with RCDC. For a straight channel MHA, when the aperture size is reduced, the transmission peaks have a blue-shift. The same result is observed for a smaller gap throat for the RCDC structure. For the rectangular holes with a high length-width ratio, a similar blue-shift in the transmission peaks as well as a narrower full width at half maximum (FWHM) are observed. The asymmetry from the rectangular shape gives this structure high selectivity for light with different polarizations. Furthermore, the RCDC shape gives extra degrees of geometrical variables to 2D-MHA for tuning the location of the transmission peak and FWHM. The tunable transmission property of this structure shows promise for applications in tunable filters, photonic circuits, and biosensors.text
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"Plasmonic properties of metallic nanostructures." Thesis, 2010. http://hdl.handle.net/1911/62086.
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Based on the plasmon hybridization theory, this thesis provides physical understanding of the plasmonic nature of metallic nanostructures. Metallic films and nanoshell particles exhibit bonding and antibonding plasmon resonances formed by hybridization of plasmon resonances associated with the two surfaces confining the metal. For both structures the lower energy bonding plasmon resonance is characterized by symmetric alignment of the charge densities. This thesis presents a physically intuitive explanation for why the repulsive symmetric charge alignment results in a low energy bonding plasmon. It also shows that the plasmon dispersion for a planar thin film can be obtained from the plasmon resonances of a metallic nanoshell in the limit of infinite radius.
After clarifying the nature of plasmon modes of thin metal films, the optical properties of an individual nanohole in a thin metallic film are examined theoretically and experimentally. Subwavelength holes, one of the most important structures in nanophotonics, give rise to extraordinary transmission when patterened in arrays. The individual holes provided a site for excitation of the underlying thin film surface plasmons. It is shown that both hole diameter and film thickness determine the energy of the optical resonance. I also show that the hole plasmon resonance (HPR) depends strongly on the polarization of the incident light due to the optical coupling between antibonding film plasmon modes and perpendicularly polarized light to the film surface.
The hybridization scheme is extended to the coherent coupling between the localized plasmons of a nanoshell and the excitons of J-aggregate molecules adsorbed on the metallic nanoparticle surface. Timing the nanoshell plasmon resonant energies across the exciton energy of the J-aggregate obtains hybridized energies for plasmon-exciton coupling. The coupling strength depends on the specific plasmon mode of the nanoshell coupled to the exciton mode of the J-aggregate. Experimental data of optical extinction spectra is reproduced by using Mie theory, and the plasmon-exciton coupling of nanoshell/J-aggregate complexes systems can be quantitatively as well as qualitatively understood based on Gans theory.
The plasmon hybridization theory can be also applied to various shapes of nanopartides using particular coordinate systems. This thesis investigate the optical properties of metallic toroidal nanoparticles using the plasmon hybridization theory. For incident light polarized in the plane of the torus, a low energy dipolar plasmon resonance and a high energy resonance contributed by several higher order torus modes appear in the optical spectra. The low energy node is highly tunable with the aspect ratio in terms of two characteristic radii of tori. For perpendicular polarization, the plasmon resonance is weakly dependent on the aspect ratio because the excited higher order torus modes are closely spaced. Optical spectra calculated by plasmon hybridization method show excellent agreement with numerical finite difference time domain calculation results.
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Katyal, Jyoti. "Plasmonic properties of aluminiam nanostructures." Thesis, 2014. http://localhost:8080/iit/handle/2074/6578.
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