Rozprawy doktorskie: „Plasmonic applications”

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Adleman, James R. Psaltis Demetri Psaltis Demetri. "Plasmonic nanoparticles for optofluidic applications /". Diss., Pasadena, Calif. : California Institute of Technology, 2009. http://resolver.caltech.edu/CaltechETD:etd-05102009-103332.

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Balasa, Ionut Gabriel. "Plasmonic Nanostructures for Biosensing Applications". Doctoral thesis, Università degli studi di Padova, 2018. http://hdl.handle.net/11577/3426821.

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The aim of this work is the study, the design and the nanofabrication of innovative plasmonic nanostructured materials to develop label-free optical biosensors. Noble metalbased nanostructures have gained interest in the last years due to their extraordinary optical properties, which allow to develop optical biosensors able to detect very low concentrations of specific biomolecules, called analyte, down to the picomolar range. Such biosensors rely on the Surface Plasmon Resonance (SPR) excitation which occurs under specific conditions that depend both on the morphology of the nanostructure and on the adjacent dielectric medium. Therefore, the binding of the biomolecules to metal surfaces is revealed as a change in the SPR condition. Four kinds of nanostructures are investigated in this work: ordered and disordered nanohole array (o-NHA, d-NHA), nanoprism array (NPA) and nanodisk array (NDA). The o-NHA and d-NHA consist of a thin metallic film (50 - 100 nm) patterned with, respectively, a hexagonal and a disordered array of circular holes. The NPA consists of a honeycomb lattice of triangle shaped nanoprisms with edges of about 100 - 200 nm and height of 40 - 80 nm. Finally, the NDA consists of a disordered array of non-interacting disks with 100 - 300 nm diameter and 40 - 80 nm height. The first two support the Extended-SPR whereas the last two, due to their three-dimensional confinement, present Localized-SPR property. Two colloidal techniques are employed for the scalable and cost-effective synthesis of wide areas of nanostructures that allow a fine control of the morphology: NanoSphere Lithography (NSL) and Sparse Colloidal Lithography (SCL). Ordered arrays were nanofabricated by NSL (i.e., NPA and o-NHA) whereas disordered nanostructures were synthesized by the SCL (i.e., NDA and d-NHA). Firstly, the nanostructures are simulated by Finite Element Method (FEM) computations and their performances in revealing small variations of the dielectric medium at the interface is evaluated as a function of their geometrical parameters. Simulated local sensitivities range from 3.1 nm/RIU of the o-NHA up to 13.6 nm/RIU of the NPA. Afterwards, the sensing performances are evaluated experimentally with nanofabricated samples and comparable but slightly smaller sensitivities are obtained. Secondly, a proof-of-concept protocol for the detection assay, that relies on the binding of streptavidin protein to the biotinylated gold surfaces, is exploited to test the nanostructures as biosensors. A 4.4 nM limit of detection is reached with the best performing biosensor (NPA) and picomolar ones are expected for NPA and NDA with a suitable improvement of the functionalization protocol. Finally, complementary single stranded RNA molecules were used, respectively, as bioreceptor and analyte. Revealing short sequences of non-coding RNA, called microRNA, is fundamental for the medical research since these oligonucleotides act as biomarkers for specific diseases, like tumors. Signals of about 13 nm are obtained from the binding of bioreceptor to the nanostructure and from the hybridization of the analyte oligonucleotide at saturation concentrations (∼ 1 μM), indicating that for the moment the developed protocol is quite effective down to the 100 nM range. Of course, for reading the nm or even sub-nM range further optimizations are needed.

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Steven, Christopher R. "Plasmonic metal nanoparticles : synthesis and applications". Thesis, University of Strathclyde, 2017. http://digitool.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=27939.

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Plasmonic metal nanoparticles are widely exploited in academia and industry for use in various assay types. In collaboration with an industrial partner, BBI Solutions, the work here details investigations into the production and use of the plasmonic nanoparticles. The work was split into two themes. The first of these was flow chemistry of nanoparticles, covering a microfluidic assay platform and continuous colloid production. In chapter one, a novel microfluidic assay platform was developed which facilitated the transfer of multiple, sequential bench-top procedures into a single device. This allowed the rapid detection of a sugar binding protein to be demonstrated. The microfluidic system included all pre-detection steps involved in employing the specific aggregation of functionalised silver nanoparticles. Straightforward detection of the protein was demonstrated at concentrations lower than those achieved using comparable methods in the literature. In the second chapter, a novel bench-top scale continuous reactor for the production of gold nanoparticles was developed. It was found that the continuous stirred tank reactor was generally unsuitable for this synthesis. A laminar tubular reactor was more successful but fouling of the reactor material was a significant obstacle to production of good quality colloid. In both cases, nanoparticles produced in a batch synthesis were of more consistent quality. This suggested that further work was needed to develop a competitive continuous production method. The second research theme was development of a novel nanoparticle assembly assay, based on DNA assembly. In chapter three it was found that current tools for the understanding of dynamic DNA structure were limited. This led to the first use of an existing coarse grain model to determine thermodynamic properties of DNA assembly. Analysis showed that the results were comparable with the best simulation models shown in the literature, while being generated much more quickly and at less computational expense.

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Sil, Devika. "SYNTHESIS AND APPLICATIONS OF PLASMONIC NANOSTRUCTURES". Diss., Temple University Libraries, 2015. http://cdm16002.contentdm.oclc.org/cdm/ref/collection/p245801coll10/id/364016.

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Chemistry
Ph.D.
The localized surface plasmon resonance (LSPR), arising due to the collective oscillation of free electrons in metal nanoparticles, is a sensitive probe of the nanostructure and its surrounding dielectric medium. Synthetic strategies for developing surfactant free nanoparticles using ultrafast lasers providing direct access to the metallic surface that harvest the localized surface plasmons will be discussed first followed by the applications. It is well known that the hot carriers generated as a result of plasmonic excitation can participate and catalyze chemical reactions. One such reaction is the dissociation of hydrogen. By the virtue of plasmonic excitation, an inert metal like Au can become reactive enough to support the dissociation of hydrogen at room temperature, thereby making it possible to optically detect this explosive gas. The mechanism of sensing is still not well understood. However, a hypothesis is that the dissociation of hydrogen may lead to the formation of a metastable gold hydride with optical properties distinct from the initial Au nanostructures, causing a reversible increase in transmission and blue shift in LSPR. It will also be shown that by tracking the LSPR of bare Au nanoparticles grown on a substrate, the adsorption of halide ions on Au can be detected exclusively. The shift in LSPR frequency is attributed to changes in electron density rather than the morphology of the nanostructures, which is often the case.
Temple University--Theses

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Hajebifard, Akram. "Plasmonic Nano-Resonators and Fano Resonances for Sensing Applications". Thesis, Université d'Ottawa / University of Ottawa, 2021. http://hdl.handle.net/10393/41616.

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Different types of plasmonic nanostructures are proposed and examined experimentally and theoretically, with a view towards sensing applications. First, a self-assembly approach was developed to create arrays of well-ordered glass-supported gold nanoparticles (AuNPs) with controllable particle size and inter-particle spacing. Then, a periodic array of gold nano-disks (AuNDs) supported by a Bragg reflector was proposed and examined in a search for Fano resonances in its optical response. Arrays of heptamer-arranged nanoholes (HNH) in a thin gold film were also proposed and explored theoretically and experimentally, revealing a very rich spectrum of resonances, several exhibiting a Fano lineshape. A commercial implementation of the vectorial finite element method (FEM) was used to model our plasmonic structures. Taking advantage of the periodic nature of the structures, a unit cell containing a single element was modelled. The transmittance, reflectance or absorbance spectra were computed, and the associated electromagnetic fields were obtained by solving the vector wave equations for the electromagnetic field vectors throughout the structures, subject to the applicable boundary conditions, and the applied source fields. The sensing performance of the structures, based on the bulk sensitivity, surface sensitivity and figure of merit (FOM) was calculated. First, a novel bottom-up fabrication approach was applied (by our collaborators) to form a periodic array of AuNPs with controllable size over large areas on SiO2 substrates. In this method, self-assembly of block copolymer micelles loaded with metal precursors was combined with a seeding growth route to create ordered AuNPs of desired size. It was shown that this new fabrication method offers a new approach to tune the AuNP size and edge-to-edge inter-particle spacing while preserving the AuNP ordering. The optical characteristics of the AuNP arrays, such as their size, interparticle spacing, localized surface plasmon resonance (LSPR) wavelength, and bulk sensitivity, were examined, numerically and experimentally. This proposed novel fabrication method is applicable for low-cost mass-production of large-area arrays of high-quality AuNPs on a substrate for sensing applications. Then, we proposed and examined the formation of Fano resonances in a plasmonic-dielectric system consisting of uncoupled gold nano-disk (AuND) arrays on a quarter-wave dielectric stack. The mechanism behind the creation of Fano resonances was explained based on the coherent interference between the reflection of the Bragg stack and the LSPPs of the AuNDs. Fano parameters were obtained by fitting the computational data to the Fano formula. The bulk sensitivities and figure of merit of the Fano resonances were calculated. This plasmonic structure supports Fano resonances with a linewidth around 9 nm which is much narrower than the individual AuND LSPP bandwidth ( 80 nm) and the Bragg stack bandwidth ( 100 nm). Supporting Fano resonances with such a narrow linewidth, the structure has a great potential to be used for sensing applications. Also, this metallic-dielectric nanostructure requires no near-field coupling between AuNDs to generate the Fano resonances. So, the AuNDs can be located far enough from each other to simplify the potential fabrication process. The optical properties of HNH arrays on an SiO2 substrate were investigated, numerically and experimentally. Helium focused ion beam (HeFIB) milling was applied (by Dr. Choloong Hahn) to fabricate well-ordered and well-defined arrays of HNHs. Transmittance spectra of the structures were obtained as the optical response, which exhibits several Fano resonances. Then, the mechanism behind the formation of the Fano resonances was explained, and the sensing performance of the structure was inspected by measuring the bulk sensitivities. This array of nanohole cluster is exciting because it supports propagating SPPs and LSPPs, and also Wood’s anomaly waves, which makes the optical response very rich in excitations and spectral features. Also, as a periodic array of sub-wavelength metallic nanoholes, the system produces extraordinary optical transmission - highly enhanced transmission through (otherwise) opaque metallic films at specific wavelengths, facilitating measurement acquisition in transmission.

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Fairbairn, Natasha. "Imaging of plasmonic nanoparticles for biomedical applications". Thesis, University of Southampton, 2013. https://eprints.soton.ac.uk/353976/.

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Plasmonic nanoparticles show potential for numerous different biomedical applications, including diagnostic applications such as targeted labelling and therapeutic applications such as drug delivery and therapeutic hyperthermia. In order to support the development of these applications, imaging techniques are required for imaging and characterising nanoparticles both in isolation and in the cellular environment. The work presented in this thesis relates to the use and development of two different optical techniques for imaging and measuring the localised surface plasmon resonance of plasmonic nanoparticles, both for isolated particles and for particles in a cellular environment. The two techniques that have been used in this project are hyperspectral darkfield microscopy and spatial modulation microscopy. Hyperspectral darkfield microscopy is a darkfield technique in which a supercontinuum light source and an acousto-optic tuneable filter are used to collect darkfield images which include spectral information. This technique has been used to measure the spectra of single nanoparticles of different shapes and sizes, and nanoparticle clusters. The results of some of these measurements have also been correlated with finite element method simulations and transmission electron microscope images. The hyperspectral darkfield technique has also been used to image cells that have been incubated with nanoparticles, demonstrating that this technique may also be used to measure the spectra of nanoparticle clusters on a cellular background. Spatial modulation microscopy is based on fast modulation of the position of a nanoparticle in the focus of an optical beam. This modulation results in a variation in transmitted intensity, which can be detected with very high sensitivity using a lock-in amplifier. Since, for biological imaging applications it is desirable to be able to image, for example whole cells in real time, a fast scanning version of this technique has been implemented, which increases the applicability of the technique to imaging of nanoparticles in cells

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He, Jie. "Plasmonic Nanomaterials for Biosensing, Optimizations and Applications". University of Cincinnati / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1522336210516443.

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Perino, Mauro. "Characterization of plasmonic surfaces for sensing applications". Doctoral thesis, Università degli studi di Padova, 2015. http://hdl.handle.net/11577/3424012.

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My research activity during the Ph. D. period has been focused on the simulation and the experimental characterization of Surface Plasmon Polaritons (SPP). Surface Plasmon Polaritons are evanescent electromagnetic waves that propagate along a metal/dielectric interface. Since their excitation momentum is higher than that of the photons inside the dielectric medium, they cannot be excited just by lighting the interface, but they need some particular coupling configurations. Among all the possible configurations the Kretschmann and the grating are those largely widespread. When the SPP coupling conditions are reached, abrupt changes of some components of the light reflected or transmitted at the metal/dielectric interface appear. Usually this resonances are characterized by a minimum of the reflectance acquired as a function of the incident angle or light wavelength. Several experimental methods are available to detect these SPP resonances, for instance by monitoring the light intensity, its polarization or its phase. Changes in the physical conditions of the metal/dielectric interface produce some changes of the SPP coupling constant, and consequently a shift in the resonance position. If these changes derive from a molecular detection process, it is possible to correlate the presence of the target molecules to the resonance variations, thus obtaining a dedicated SPP sensor. I focused the first part of my Ph.D. activity on the simulation of SPP resonances by using several numerical techniques, such as the Rigorous Coupled Wave Analysis method, the Chandezon method, and the Finite Element Method implemented through Comsol v3.5. I simulated the SPP resonance in the Kretschmann coupling configuration for plane and nano-grating structured metal/dielectric interfaces. Afterward, I calculated the SPP resonance behaviour for grating and bi-dimensional periodic structures lighted in the conical configuration. Furthermore, I analysed the correlations between the grating coupling method and the Kretschamann coupling method. Through all these simulations, I studied the sensitivity of the different SPP resonances to the refractive index variation of the dielectric in contact with the metal. In this way, I was able to find a new parameter suitable for describing the SPP resonance, i.e., the azimuthal angle. By considering this particular angle, the sensitivity of the SPP resonances could be properly set according to the experimental needs and, even more important, noticeably increased to high values. Experimentally I used two opto-electronic benches, one for the Kretschmann configuration and one for the conical mounting configuration. I have performed experimental measurements, in order to compare the experimental data with the simulations. In particular the following conditions were tested: • Plane interface, Kretschmann configuration • Nanostructured grating, Kretschmann configuration • Nanostructured grating, Conical configuration I focused my attention on the nano-structured grating in conical mounting configuration. I found an innovative way to characterize its SPP resonances, by measuring the transmitted signal as a function of the incident and azimuthal angles. The transmittance and the azimuthal sensitivities were characterized with the gratings in both air and water. In order to study the experimental azimuthal sensitivity, I changed the liquid refractive index in contact with the grating by using different water/glycerol solutions. Moreover, I functionalized the surface by using thiolated molecules that form Self Assembled Monolayer onto the metallic layer. In this way, I was able to change the SPP coupling constants and detect the corresponding azimuthal resonance shifts. I also detected the immobilization of an antibody layer onto the metallic surface of the plasmonic interface. All the devices I used in the experimental measurements were produced by the University spin off Next Step Engineering.
Durante il mio periodo di dottorato in Scienza e Tecnologia dell’Informazione l’attività di ricerca principale è stata focalizzata sulla caratterizzazione, simulativa e sperimentale, dei plasmoni di superficie. I plasmoni di superficie sono onde elettromagnetiche evanescenti che si propagano all’interfaccia tra un mezzo metallico ed un mezzo dielettrico. Il loro vettore d’onda è più elevato rispetto a quello della luce nel mezzo dielettrico. Per poter quindi generare l’eccitazione si devono utilizzare particolari tecniche di accoppiamento. I due metodi più diffusi sono l’accoppiamento Kretschmann e l’accoppiamento tramite reticolo. Una volta raggiunte le condizioni di accoppiamento dei plasmoni di superficie, si realizza il fenomeno della risonanza plasmonica, la quale si manifesta attraverso brusche variazioni nelle componenti della luce riflessa o trasmessa dalla superficie. Tipicamente si può registrare un minimo della riflettanza in funzione dell’angolo di incidenza della luce sulla superficie. Esistono, tuttavia, anche altre modalità per registrare e misurare queste risonanze, come ad esempio monitorando intensità, polarizzazione o fase della luce trasmessa e riflessa dalla superficie, in funzione della sua lunghezza d’onda o dei sui angoli di incidenza. Le variazioni chimico/fisiche che avvengono all’interfaccia metallo/dielettrico, modificando la costante di accoppiamento plasmonica, cambiano le condizioni di risonanza. Nel caso in cui le variazioni all’interfaccia siano dovute ad un processo di riconoscimento molecolare è possibile rilevare le molecole d’interesse valutando i cambiamenti della risonanza plasmonica, fornendo così l’opportunità per l’implementazione di sensori specifici. L’attività di dottorato è stata focalizzata innanzitutto sullo studio teorico del comportamento della risonanza plasmonica, utilizzando varie tecniche di simulazione numerica: il metodo RCWA (Rigorous Coupled Wave Analysis), Il metodo di Chandezon ed il metodo agli elementi finiti, implementato tramite Comsol v3.5. Ho poi affrontato lo studio, tramite simulazioni, delle risonanze di superficie in configurazione Kretschmann, sia per interfacce metallo/dielettrico piane sia per interfacce nano-strutturate. Considerando una configurazione conica, ho simulato le risonanze di superficie per nano-strutture reticolari e per nano-strutture bi-dimensionali periodiche. Inoltre ho analizzato il legame tra le modalità di accoppiamento grating e Kretschmann. Tramite queste simulazioni mi è stato possibile valutare e studiare la sensibilità delle varie risonanze plasmoniche alla variazione di indice di rifrazione, quando essa avviene all’interfaccia metallo/dielettrico. È stato così possibile identificare un nuovo parametro per descrivere la risonanza plasmonica e la sua sensibilità, ossia l’angolo azimutale, definito come l’angolo tra il vettore del grating ed il piano di scattering della luce. Considerando questo particolare angolo, la sensibilità del sensore può essere controllata con un’opportuna regolazione degli altri parametri coinvolti nell’eccitazione plasmonica, consentendole di raggiungere valori molto elevati. Successivamente, grazie all’utilizzo di due banchi, uno per la configurazione Kretschmann ed uno per la misura di reticoli nano-strutturati in configurazione conica, ho realizzato delle campagne di misure sperimentali. E’ stato così possibile confrontare i risultati sperimentali con le simulazioni numeriche per le seguenti condizioni: • Interfaccia piana, configurazione Kretschmann • reticolo nano-strutturato, configurazione Kretschmann • reticolo nano-strutturato, configurazione conica L’attività sperimentale si è particolarmente focalizzata sul reticolo nano-strutturato, sia per l’innovativa modalità di caratterizzazione delle sue risonanze plasmoniche (valutazione del segnale trasmesso in funzione dell’angolo di incidenza e dell’angolo azimutale), sia per l’elevata sensibilità ottenuta valutando la variazione dell’angolo azimutale. La caratterizzazione è stata effettuata sia per il reticolo esposto all’aria che per il reticolo immerso in un liquido (tipicamente acqua). Per poter verificare il comportamento della sensibilità azimutale ho variato l’indice di rifrazione del liquido in contatto con la superficie utilizzando soluzioni miste di acqua e glicerolo. Inoltre, tramite tecniche di funzionalizzazione della superficie, ovvero applicando delle molecole thiolate che vengono adsorbite sulla parte metallica dell’interfaccia, mi è stato possibile variare le costanti di accoppiamento plasmonico, in modo da verificare la capacità del dispositivo di rilevare l’avvenuta creazione di uno strato molecolare sulla superficie. Inoltre ho positivamente verificato la capacità di immobilizzare uno strato di anticorpi sulla superficie plasmonica. Tutte le misure sperimentali che ho svolto in questa tesi sono state effettuate su sensori con superfici piane o nano-strutturate prodotte dallo spin-off universitario Next Step Engineering, con il quale ho collaborato durante il percorso di ricerca.

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Danilov, Artem. "Design, characterisation and biosensing applications of nanoperiodic plasmonic metamaterials". Thesis, Aix-Marseille, 2018. http://www.theses.fr/2018AIXM0110/document.

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Cette thèse considère de nouvelles architectures prometteuses des métamatériaux plasmoniques pour biosensing, comprenant: (I) des réseaux périodiques 2D de nanoparticules d'Au, qui peuvent supporter des résonances des réseaux de surface couplées de manière diffractive; (II) Reseaux 3D à base de cristaux plasmoniques du type d'assemblage de bois. Une étude systématique des conditions d'excitation plasmonique, des propriétés et de la sensibilité à l'environnement local dans ces géométries métamatérielles est présentée. On montre que de tels réseaux peuvent combiner une très haute sensibilité spectrale (400 nm / RIU et 2600 nm / RIU, ensemble respectivement) et une sensibilité de phase exceptionnellement élevée (> 105 deg./RIU) et peuvent être utilisés pour améliorer l'état actuel de la technologie de biosensing the-art. Enfin, on propose une méthode de sondage du champ électrique excité par des nanostructures plasmoniques (nanoparticules uniques, dimères). On suppose que cette méthode aidera à concevoir des structures pour SERS (La spectroscopie du type Raman à surface renforcée), qui peut être utilisée comme une chaîne d'information supplémentaire à un biocapteur de transduction optique
This thesis consideres novel promissing architechtures of plasmonic metamaterial for biosensing, including: (I) 2D periodic arrays of Au nanoparticles, which can support diffractively coupled surface lattice resonances; (II) 3D periodic arrays based on woodpile-assembly plasmonic crystals, which can support novel delocalized plasmonic modes over 3D structure. A systematic study of conditions of plasmon excitation, properties and sensitivity to local environment is presented. It is shown that such arrays can combine very high spectral sensitivity (400nm/RIU and 2600 nm/RIU, respectively) and exceptionally high phase sensitivity (> 105 deg./RIU) and can be used for the improvement of current state-of-the-art biosensing technology. Finally, a method for probing electric field excited by plasmonic nanostructures (single nanoparticles, dimers) is proposed. It is implied that this method will help to design structures for SERS, which will later be used as an additional informational channel for biosensing

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Bartkowiak, Dorota. "MgF2-coated gold nanostructures as a plasmonic substrate for analytical applications". Doctoral thesis, Humboldt-Universität zu Berlin, 2018. http://dx.doi.org/10.18452/19584.

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Plasmonische Substrate stellen ein leistungsstarkes Werkzeug für analytische Anwendungen dar. Neue plasmonische Substrate werden entwickelt, um das Spektrum ihrer Anwendungen und die Nachweisgrenzen der analytischen Spektroskopie zu erweitern. Diese Arbeit setzte sich zum Ziel, plasmonische Nanostrukturen mit Magnesiumfluorid zu beschichten. Magnesiumfluoridbeschichtungen sind zwar porös, weisen aber eine hohe mechanische Stabilität und außergewöhnliche optische Eigenschaften auf (niedrigen Brechungsindexes, großen optischen Fensters). Die Kombination dieser Eigenschaften mit den positiven Eigenschaften von plasmonischen Nanostrukturen kann zu fortschrittlichen plasmonischen Substraten für analytische Anwendungen führen. Diese Arbeit bietet zwei Ansätze für die Beschichtung der plasmonischen Nanostrukturen an die Core-Shell-Nanopartikelherstellung, die einen plasmonischen Core enthält und die Beschichtung von auf Glas immobilisierten plasmonischen Nanostrukturen. Über Metal@metal Fluoride Core-Shell-Nanopartikel wurde in der Literatur noch nichts berichtet. Daher Au@MgF2wurde ein Ansatz verfolgt, der auf dem Wissen über Metall-@Metalloxide und Metallfluoride@Metallfluoride basiert und die Synthese von Core-Shell-Nanopartikeln ermöglicht. Die erhaltenen Strukturen wurden mit elektronenmikroskopischen Methoden charakterisiert. Der zweite Ansatz bestand in der Immobilisierung von Goldnanopartikeln auf Glas und deren Beschichtung mit Magnesiumfluorid. Diese Fertigungsart verleiht eine hohe mechanische Stabilität und wissenswerte optische Eigenschaften an plasmonischen Substraten, die sich durch eine hohe nanoskopische Homogenität der Goldnanopartikelverteilung auszeichnen und optischer Signale, die echte analytische Anwendungen ermöglichen, ermittelt. Die Beschichtung von auf Glas mit Magnesiumfluorid immobilisierten Goldnanopartikeln führt zu einem sehr vielversprechenden Substrat , das in Zukunft für Sensorik und andere Anwendungen verwendet werden kann.
Plasmonic substrates can be a powerful tool for analytical applications. In order to broaden the spectrum of their applications and to push the detection limits of analytical spectroscopy, new plasmonic substrates are developed. The motivation of this work was to coat plasmonic nanostructures with magnesium fluoride. Coatings of magnesium fluoride are porous but exhibit high mechanical stability and extraordinary optical properties including a low refractive index and a wide optical window. Combining these properties with the beneficial properties of plasmonic nanostructures can lead to advanced plasmonic substrates for analytical applications. Two approaches for coating of the plasmonic nanostructures are proposed in this work: a core-shell nanoparticles fabrication and coating of plasmonic nanostructures immobilized on glass. The fabrication of Au@MgF2 core-shell nanoparticles turned out to be an extremely challenging approach. Such systems have not been reported in the literature yet. Therefore, an approach based on knowledge of metal@metal oxides and metal fluorides@metal fluorides core-shell nanoparticles synthesis was undertaken. The obtained structures were characterized using electron microscopy methods. Due to the numerous difficulties in the synthesis and characterization this way of coating plasmonic nanostructures with magnesium fluoride was not further processed. The approach based on immobilization of gold nanoparticles on glass and coating them with magnesium fluoride using a dip-coating method provides plasmonic substrates that are characterized by a high nanoscopic homogeneity of the gold nanoparticles distribution, a high mechanical stability, interesting optical properties and enhancement factors of optical signals that allow for real analytical applications. The coating of gold nanoparticles immobilized on the glass with magnesium fluoride results in very promising substrate that can be used for sensing and other applications in the future.

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Song, Yi. "Plasmonic waveguides and resonators for optical communication applications". Doctoral thesis, KTH, Fotonik, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-33596.

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Photonic circuits can transmit data signals in a much higher speed thanconventional electronic circuits. However, miniaturization of photonic circuitsand devices is hindered by the existence of light diffraction limit. A promisingsolution to this problem is by exploiting plasmonic systems for guiding andmanipulating signals at optical frequencies. Plasmonic devices are generallycomposed of noble metals and dielectrics, whose interfaces can confine surfaceplasmon polaritons, a hybrid wave that is free of diffraction limit. Plasmonicwaveguides and devices are serious contenders for achieving next-generationphotonic integrated circuits with a density comparable to the electronic counterpart. This thesis addresses the design issues of passive plasmonic devices whichare critical for realization of photonic integration, including plasmonic waveguides,splitters, couplers, and resonators, investigated with both the finitedifferencetime-domain method and the finite-element method. In particularwe present, firstly, a coupler which efficiently couples light between a silicondielectric waveguide and a hybrid plasmonic (HP) waveguide. A coupling efficiencyas high as 70% is realized with a HP taper as short as 0.4μm. Theexperimental result agrees well with the numerical simulation. Secondly, wenumerically investigate and optimize the performances of 1×2 and 1×3 HPmultimode interferometers (MMIs), which split light from a silicon waveguideto multiple HP waveguides. Total transmission over 75% can be achieved inboth cases. Thirdly, we study the coupling and crosstalk issues in plasmonicwaveguide systems. Several methods for crosstalk reduction are proposed.Finally, HP nanodisk micro-cavities are designed and are numerically characterized.With a radius of 1μm, a high quality factor of 819 and a highPurcell factor of 1827 can be simultaneously achieved, which can be useful forrealizing efficient nano-lasers.
QC 20110523

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Rosman, Christina [Verfasser]. "Biological applications of plasmonic metal nanoparticles / Christina Rosman". Mainz : Universitätsbibliothek Mainz, 2015. http://d-nb.info/1076882633/34.

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Chen, Xi. "Photothermal Effect in Plasmonic Nanostructures and its Applications". Doctoral thesis, KTH, Optik och Fotonik, OFO, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-143754.

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Plasmonic resonances are characterized by enhanced optical near field and subwavelength power confinement. Light is not only scattered but also simultaneously absorbed in the metal nanostructures. With proper structural design, plasmonic-enhanced light absorption can generate nanoscopically confined heat power in metallic nanostructures, which can even be temporally modulated by varying the pump light. These intrinsic characters of plasmonic nanostructures are investigated in depth in this thesis for a range of materials and nanophotonic applications. The theoretical basis for the photothermal phenomenon, including light absorption, heat generation, and heat conduction, is coherently summarized and implemented numerically based on finite-element method. Our analysis favours disk-pair and particle/dielectric-spacer/metal-film nanostructures for their high optical absorbance, originated from their antiparallel dipole resonances. Experiments were done towards two specific application directions. First, the manipulation of the morphology and crystallinity of Au nanoparticles (NPs) in plasmonic absorbers by photothermal effect is demonstrated. In particular, with a nanosecond-pulsed light, brick-shaped Au NPs are reshaped to spherical NPs with a smooth surface; while with a 10-second continuous wave laser, similar brick-shaped NPs can be annealed to faceted nanocrystals. A comparison of the two cases reveals that pumping intensity and exposure time both play key roles in determining the morphology and crystallinity of the annealed NPs. Second, the attempt is made to utilize the high absorbance and localized heat generation of the metal-insulator-metal (MIM) absorber in Si thermo-optic switches for achieving all-optical switching/routing with a small switching power and a fast transient response. For this purpose, a numerical study of a Mach-Zehnder interferometer integrated with MIM nanostrips is performed. Experimentally, a Si disk resonator and a ring-resonator-based add-drop filter, both integrated with MIM film absorbers, are fabricated and characterized. They show that good thermal conductance between the absorber and the Si light-guiding region is vital for a better switching performance. Theoretical and experimental methodologies presented in the thesis show the physics principle and functionality of the photothermal effect in Au nanostructures, as well as its application in improving the morphology and crystallinity of Au NPs and miniaturized all-optical Si photonic switching devices.

QC 20140331

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Li, Xiaoli. "Spintronic and plasmonic applications of electrodeposition on semiconductors". Thesis, University of Southampton, 2009. https://eprints.soton.ac.uk/66205/.

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In this thesis, metal electrodeposition on semiconductor substrates is investigated. We show that electrodeposition of metals on n-type Si and Ge is an excellent method to create Schottky barriers and that this method has a number of unique advantages over other (physical) deposition methods. These advantages can be used to improve the prospects of applications in the area of Spintronics and Plasmonics. Firstly, the excellent current-voltage and capacitance-voltage characteristics of electrodeposited Schottky barriers indicate that they have an ideality factor close to unity and that the reverse bias leakage is orders of magnitude smaller than in evaporated Schottky barriers. These characteristics can be used to make highly doped Schottky barriers in which all reverse bias current is due to tunnelling. For magnetic metals, these Schottky barriers hence allow spin-conserved conduction which is a necessary step towards semiconductor spin valves and spin transistors. Secondly, electrodeposition is not a line-of-sight-technique and can hence be used to grow three dimensional structures when an appropriate pattern is created. Self assembly of latex spheres is shown to change both qualitative and quantitatively upon using a lithographically defined pattern. By using electrodeposition of gold around this latex sphere pattern nano-void array photonic crystals are created. We show that plasmonic modes are detectable in these arrays opening up the path to on-chip optical communication.

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Ahmadivand, Arash. "Plasmonic Nanoplatforms for Biochemical Sensing and Medical Applications". FIU Digital Commons, 2018. https://digitalcommons.fiu.edu/etd/3576.

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Plasmonics, the science of the excitation of surface plasmon polaritons (SPP) at the metal-dielectric interface under intense beam radiation, has been studied for its immense potential for developing numerous nanophotonic devices, optical circuits and lab-on-a-chip devices. The key feature, which makes the plasmonic structures promising is the ability to support strong resonances with different behaviors and tunable localized hotspots, excitable in a wide spectral range. Therefore, the fundamental understanding of light-matter interactions at subwavelength nanostructures and use of this understanding to tailor plasmonic nanostructures with the ability to sustain high-quality tunable resonant modes are essential toward the realization of highly functional devices with a wide range of applications from sensing to switching. We investigated the excitation of various plasmonic resonance modes (i.e. Fano resonances, and toroidal moments) using both optical and terahertz (THz) plasmonic metamolecules. By designing and fabricating various nanostructures, we successfully predicted, demonstrated and analyzed the excitation of plasmonic resonances, numerically and experimentally. A simple comparison between the sensitivity and lineshape quality of various optically driven resonances reveals that nonradiative toroidal moments are exotic plasmonic modes with strong sensitivity to environmental perturbations. Employing toroidal plasmonic metasurfaces, we demonstrated ultrafast plasmonic switches and highly sensitive sensors. Focusing on the biomedical applications of toroidal moments, we developed plasmonic metamaterials for fast and cost-effective infection diagnosis using the THz range of the spectrum. We used the exotic behavior of toroidal moments for the identification of Zika-virus (ZIKV) envelope proteins as the infectious nano-agents through two protocols: 1) direct biding of targeted biomarkers to the plasmonic metasurfaces, and 2) attaching gold nanoparticles to the plasmonic metasurfaces and binding the proteins to the particles to enhance the sensitivity. This led to developing ultrasensitive THz plasmonic metasensors for detection of nanoscale and low-molecular-weight biomarkers at the picomolar range of concentration. In summary, by using high-quality and pronounced toroidal moments as sensitive resonances, we have successfully designed, fabricated and characterized novel plasmonic toroidal metamaterials for the detection of infectious biomarkers using different methods. The proposed approach allowed us to compare and analyze the binding properties, sensitivity, repeatability, and limit of detection of the metasensing devices

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Russo, Valentina. "Plasmonic Au/Ag ordered nanoarrays for biosensing applications". Doctoral thesis, Università degli studi di Padova, 2016. http://hdl.handle.net/11577/3425233.

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The aim of the present work is the study and the nanofabrication of innovative plasmonic nanostructured materials to develop label-free optical biosensors. The motivation arises from the need to identify specific biological molecules at very low concentrations (below the picoMolar level) and with high specificity. This goal is of paramount importance for instance in diagnostics and prognostics through the early-stage detection of markers in biological fluids indicating possible altered biological processes. At the same time a fast and simple detection scheme is required, without the use of labelling strategies. The innovative plasmonic properties of noble metals (Au,Ag) nanomaterials have been investigated for biosensing applications since 1983. These plasmonic properties arise from the interaction of an electromagnetic wave with nanostructured metals, i.e., metallic structures with size in the order of or smaller than the incident field wavelength in the Vis-NIR range: their most celebrated effect is the onset of the surface plasmon resonances (SPR). Prims-coupled biosensing devices based on SPR of gold thin film (thickness lower than 100 nm) were commercialized since 1990. These systems allow to monitor biomolecular interactions and to quantify a wide range of chemical and biological species down to nanomolar concentrations. The scientific community is strongly active in the optimization of the performances of the SPR sensors in terms of sensitivity, specificity and limit of detection. The present work is based on the application of the SPR properties of ordered Au/Ag nanoarrays for biological detection, in order to investigate and optimize their sensing performances. The detection mechanism is based on the variation of the SPR for refractive index changes, which are due to analyte molecules immobilized on the nanoarray's surface. We have studied three classes of nanoarrays based on noble metals: (i) semi-nanoshell array, (ii) nanoprism array and (iii) nanohole array. Gold and silver are the best plasmonic metals for their intrinsic properties of interaction with an electromagnetic field in the Vis-NIR range. The nanoarrays were synthesized by Nanosphere Lithography, and they are based on hexagonal arrays of nanounits such as nanoprims, semi-nanoshells and nanoholes. The synthesis technique allows to finely control the morphology and the dimensions of the nanounits and, as a consequence, their optical properties. The samples based on nanoprims and semi-nanoshells support high electromagnetic field localization on their surface, which is due to the excitation of localized SPR; for this reason these systems could be very interesting sensors to detect thin analyte molecules layers with low molecular weight. The samples based on nanoholes arrays are characterized by the EOT, which is controlled by the excitation of extended SPR. The longer decay length of this kind of plasmons makes EOT particularly useful to detect also bigger molecules such as viruses or bacteria. All the samples were functionalized with the same protocol based on the biotin-streptavidin couple as the receptor-ligand scheme. The sensing performances were investigated by exposing the functionalized samples to different analyte concentrations. Moreover, the local and bulk sensitivity to refractive index changes was measured. The experimental results were also compared with numerical simulations and we found a good level of agreement between the experimental and simulated data. Silver nanoprisms arrays were also studied as SERS substrates. They were oxidized with different treatments to investigate the silver oxide effect on the SERS performances. All the obtained results in the present work indicate performances of the three investigated nanotructures, which are at the state-of-the-art with respect to literature data.
Il tema centrale del presente lavoro di dottorato è lo studio e la nanofabbricazione di materiali plasmonici inovativi nanostrutturati per lo sviluppo di biosensori ottici label-free. La motivazione risiede nell'esigenza di identificare determinate specie biologiche in concentrazioni sempre minori (inferiore al picomolare) e con una tecnologia di rilevazione altamente sensibile e specifica, al fine di rilevare la presenza di processi biologici normali o alterati. Nello stesso tempo si richiede una rilevazione veloce, semplice e che non necessiti di un marcatore ottico. Le innovative proprietà plasmoniche che caratterizzano i nanomateriali costituiti da metalli nobili (Au,Ag) sono state investigate per applicazioni biosensoristiche fin dal 1983. Queste proprietà plasmoniche derivano dall'interazione di una radiazione elettromagnetica con i metalli nanostrutturati; i.e. strutture metalliche con dimensioni dell'ordine o minore della lunghezza d'onda della radiazione incidente nel range del Vis-NIR, e si basano sulla risonanza plasmonica superficiale (SPR). Dispositivi biosensoristici basati sulla SPR di film sottili di oro (spessore inferiore a 100 nm) accoppiati con un prisma, sono in commercio dal 1990. Questi sistemi permettono di monitorare interazioni biomolecolari e di quantificare una vasta gamma di specie chimiche e biologiche, fino a concentrazioni dell'ordine del nanomolare. La comunità scientifica è fortemente attiva nel cercare di ottimizzare le prestazioni dei sensori SPR in termini di sensibilità, specificità e limite di rilevazione. Il presente lavoro si basa sull'applicazione delle proprietà SPR di nanoarray ordinati a base di Au e Ag per la rilevazione di molecole biologiche, al fine di investigarne ed ottimizzarne le prestazioni. Il meccanismo di sensing si basa sulla variazione della SPR per variazioni di indice di rifrazione, che sono dovuti all'immobilizazione di molecole analita sulla superficie dei nanoarray. Sono state studiate tre classi di nanoarray costituiti da metalli nobili: (i) semi-nanoshell array, (ii) nanoprism array and (iii) nanohole array. Oro ed Argento sono i migliori candidati per applicazioni nel campo della plasmonica per le loro proprietà intrinseche di interazione con la radiazione elettromagnetica, in particolare nelle frequenze del visibile e del vicino infrarosso. I nanoarray sono stati sintetizzati mediante la tecnica di Litografia a Nanosfere, e sono costituiti da array esagonali di nanounità, cresciute in forma di nanoprismi, semi-nanoshells e nanoholes. La tecnica di sintesi utilizzata permette di controllare finemente la morfologia e le dimensioni delle nanounità e, di conseguenza, le rispettive proprietà ottiche. I sistemi costituiti da nanoprismi o semi-nanoshells sono caratterizzati da un'elevata amplificazione di campo elettromagnetico sulla loro superficie, la quale è dovuta all'eccitazione della SPR; per questo motivo questi sistemi potrebbero essere molto interessanti per la rilevazione di spessori molto piccoli di molecole analita con un basso peso molecolare. I nanoholes arrays sono caratterizzati dalla Trasmissione Ottica Straordinaria (EOT), che può invece essere investigata per la rilevazione di molecole di grande dimensione come virus o batteri. Tutti i campioni sono stati funzionalizzati con con lo stesso protocollo di funzionalizazione basato su una coppia modello di molecole biologiche recettore-analita (biotina-streptavidina). Le proprietà di sensing sono state investigate esponendo i campioni funzionalizzati con uno specifico recettore, a differenti concentrazioni della molecola analita. Inoltre è stata misurata la sensibilità locale e bulk in risposta alle variazioni di indice di rifrazione. I risultati sperimentali sono stati anche confrontati con dei modelli teorici ottenendo un buon accordo tra il dato sperimentale e quello simulato. I nanoprismi di argento sono stati anche studiati come possibili substrati per la spettroscopia SERS. I campioni sono stati ossidati con diversi trattamenti al fine di analizzare l'effetto dell'ossido sul segnale SERS. I risultati ottenuti nel prente lavoro hanno mostrato come le tre tipologie di nanostrutture studiate mostrino performance che sono allo stato dell'arte rispetto ai valori di letteratura.

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Prasad, Janak [Verfasser]. "Sensing applications of biofunctionalised plasmonic gold nanoparticles / Janak Prasad". Mainz : Universitätsbibliothek Mainz, 2015. http://d-nb.info/1070108898/34.

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Schlickriede, Christian [Verfasser]. "Plasmonic and dielectric metalenses for nanophotonic applications / Christian Schlickriede". Paderborn : Universitätsbibliothek, 2021. http://d-nb.info/123663005X/34.

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Trevino, Jacob Timothy. "Engineering aperiodic spiral order for photonic-plasmonic device applications". Thesis, Boston University, 2013. https://hdl.handle.net/2144/11068.

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Thesis (Ph.D.)--Boston University
Deterministic arrays of metal (i.e., Au) nanoparticles and dielectric nanopillars (i.e., Si and SiN) arranged in aperiodic spiral geometries (Vogel's spirals) are proposed as a novel platform for engineering enhanced photonic-plasmonic coupling and increased light-matter interaction over broad frequency and angular spectra for planar optical devices. Vogel's spirals lack both translational and orientational symmetry in real space, while displaying continuous circular symmetry (i.e., rotational symmetry of infinite order) in reciprocal Fourier space. The novel regime of "circular multiple light scattering" in finite-size deterministic structures will be investigated. The distinctive geometrical structure of Vogel spirals will be studied by a multifractal analysis, Fourier-Bessel decomposition, and Delaunay tessellation methods, leading to spiral structure optimization for novel localized optical states with broadband fluctuations in their photonic mode density. Experimentally, a number of designed passive and active spiral structures will be fabricated and characterized using dark-field optical spectroscopy, ellipsometry, and Fourier space imaging. Polarization-insensitive planar omnidirectional diffraction will be demonstrated and engineered over a large and controllable range of frequencies. Device applications to enhanced LEDs, novel lasers, and thin-film solar cells with enhanced absorption will be specifically targeted. Additionally, using Vogel spirals we investigate the direct (i.e. free space) generation of optical vortices, with well-defined and controllable values of orbital angular momentum, paving the way to the engineering and control of novel types of phase discontinuities (i.e., phase dislocation loops) in compact, chip-scale optical devices. Finally, we report on the design, modeling, and experimental demonstration of array-enhanced nanoantennas for polarization-controlled multispectral nanofocusing, nanoantennas for resonant near-field optical concentration of radiation to individual nanowires, and aperiodic double resonance surface enhanced Raman scattering substrates.

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Pasquale, Alyssa Joy. "Engineering photonic-plasmonic devices for spectroscopy and sensing applications". Thesis, Boston University, 2012. https://hdl.handle.net/2144/32043.

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Thesis (Ph.D.)--Boston University
PLEASE NOTE: Boston University Libraries did not receive an Authorization To Manage form for this thesis or dissertation. It is therefore not openly accessible, though it may be available by request. If you are the author or principal advisor of this work and would like to request open access for it, please contact us at open-help@bu.edu. Thank you.
The control of light on the nano-scale has driven the development of novel optical devices such as biosensors, antennas and guiding elements. These applications benefit from the distinctive resonant properties of noble metal thin films and nanoparticles. Many optimization parameters exist in order to engineer nanoparticle properties for spectroscopy and sensing applications: for example, the choice of metal, the particle morphology, and the array geometry. By utilizing various designs from simple monomer gratings to more complex engineered arrays, we model and characterize plasmonic arrays for sensing applications. In this thesis, I have focused on the novel paradigm of photonic-plasmonic coupling to design, fabricate, and characterize optimized nanosensors. In particular, nanoplasmonic necklaces, which consist of circular loops of closely spaced gold nanoparticles, are designed using 3D finite-difference time-domain (FDTD) simulations, fabricated with electron-beam lithography, and characterized using dark-field scattering and surface-enhanced Raman spectroscopy (SERS) of p-mercaptoaniline (pMA) monolayers. I show that such necklaces are able to support hybridized dipolar scattering resonances and polarization-controlled electromagnetic hot-spots. In addition, necklaces exhibit strong intensity enhancement when the necklace diameter leads to coupling between the broadband plasmonic resonance and the circular resonator structure of the necklace. Hence, these necklaces lead to stronger field intensity enhancement than nanoparticle monomers and dimers, which are also carefully studied. Furthermore, by embedding a dimer into one or more concentric necklace resonators, I am able to efficiently couple radiation into the dimer hot-spot by utilizing first- and second-order far-field coupling. This nanolensing leads to an order of 6-18 times improvement in Raman enhancement over isolated dimers, which is a promising platform for compact on-chip sensors. Additionally, I have fabricated and experimentally characterized devices that were designed in my group for SERS of pMA using an optimization algorithm. The algorithm confirms that the best arrangement of nanoparticles to increase near-field intensity enhancement in a single hot-spot is to embed a dimer into particles that couple light into the hot-spot via far-field photonic radiation. These genetically optimized nanoantennas show improvement in Raman enhancement 10 times that of nanoparticle dimers, and 100 times the enhancement of optimized two-dimensional monomer diffraction gratings.
2031-01-02

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PONZELLINI, PAOLO. "Plasmonic nanopores for single molecule spectroscopy towards sequencing applications". Doctoral thesis, Università degli studi di Genova, 2019. http://hdl.handle.net/11567/939990.

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Hassan, Karim. "Fabrication and characterization of thermo-plasmonic routers for telecom applications". Phd thesis, Université de Bourgogne, 2013. http://tel.archives-ouvertes.fr/tel-00944210.

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The Dielectric Loaded Surface Plasmon Polariton Waveguides (DLSPPWs) have recently emerged as a possible solution to carry both optical and electrical signals on- chip. However, in the particular context of optical interconnects, advanced functionalities such as filtering, switching, and routing are required in order to replace in the future the equivalent electronic components which are too much power consumer and also to reduce their footprints. After presenting the interest and limitation of the leakage radiation microscopy method used all along this work, we show several active devices using thermo-sensitive polymers as the dielectric load driven electrically by Joule heating. Then we demonstrate the feasibility of all-optical systems by either doping the dielectric with metallic nanoparticles or by plasmo-thermal eect of a second plasmonic mode providing a localized heating of controlled shape. The dynamic activation of our thermo- optical devices is performed using a homemade fiber-to-fiber setup which allows us to investigate the response time of a plasmo-thermal heating as well as true datacom transmission. Some improvements of the original DLSPPWs performances are proposed by adding a metallic wall on one side of the polymer ridge. This system can act as a compact and athermal polarization converter

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Ruiz, Matias. "Analyse mathématique de résonances plasmoniques pour des nanoparticules et applications". Thesis, Paris Sciences et Lettres (ComUE), 2017. http://www.theses.fr/2017PSLEE054/document.

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Cette thèse porte sur l’étude mathématique des interactions entre la lumière et certains types de nanoparticules.À l’échelle du nanomètre, des particules métalliques comme l’or ou l’argent subissent un phénomène de résonance lorsque leurs électrons libres interagissent avec un champ électromagnétique. Cette interaction produit une augmentation du champs électrique proche et lointain, leur permettant d’améliorer la luminosité et la directivité de la lumière, confinant des champs électromagnétiques dans des directions avantageuses. Ce phénomène, appelé "résonances plasmoniques pour des nanoparticules" ouvre une porte sur une large gamme d’applications, des nouvelles techniques d’imagerie médicale à des panneaux solaires efficaces. En utilisant des techniques issues des potentiels de couches et de la théorie de la perturbation,nous proposons une étude de la dispersion d’ondes électromagnétiques par une et plusieurs nanoparticules plasmoniques, dans le cadre quasi-statique, Helmholtz et Maxwell. Nous étudions ensuite certaines applications tel que la génération de chaleur, les métasurfaces et l’imagerie super-résolue
This thesis deals with the mathematical study of the interactions between light and certain types of nanoparticles. At the nanometer scale, metal particles such as gold or silver undergo a resonance phenomenon when their free electrons interact with an electromagnetic field. This interaction results in an enhancement of the near and far electric field, enabling them to improve the brightness and the directivity of the light, confining electromagnetic fields in advantageous directions. This phenomenon, called "plasmonic resonances for nanoparticles", opens a door to a wide range of applications, from new medical imaging techniques to efficient solar panels. Using layer potentials techniques and perturbation theory, we proposea study of the scattering of electromagnetic waves by one and several plasmonic nanoparticles in the quasi-static, Helmholtz and Maxwell framework. We then study some applications such as heat generation, metasurfaces and super-resolution

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Chen, Kai. "Self-organization on Nanoparticle Surfaces for Plasmonic and Nonlinear Optical Applications". Diss., Virginia Tech, 2009. http://hdl.handle.net/10919/30111.

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This dissertation is about fabrication and functionalization of metal nanoparticles for use in plasmonic and nonlinear optical (NLO) applications. In the first two chapters, I describe a series of experiments, where I combined silver nanoparticles fabricated by nanosphere lithography with ionic self-assembled multilayer (ISAM) films, tuning the geometry of the particles to make their plasmonic resonances overlap with the frequency of optical excitation. The designed hybrid metallic/organic nanostructures exhibited large enhancements of the efficiency of second harmonic generation (SHG) compared to conventional ISAM films, causing a modified film with just 3 bilayers to be optically equivalent to a conventional 700-1000 bilayer film. SHG responses from Ag nanoparticle-decorated hybrid-covalent ISAM (HCISAM) films were investigated as the next logical step towards high-Ï ²⁺ ISAM films. I found that the plasmonic enhancement primarily stems from interface SHG. Interface effects were characterized by direct comparison of SHG signals from PAH/PCBS ISAM films and PAH/PB HCISAM films. Though interface &chi²⁺ is substantially smaller in PAH/PCBS than in PAH/PB, plasmonically enhanced PAH/PCBS films exhibit stronger NLO response. I propose that the structure of PAH/PB film makes its interface more susceptible to disruptions in the nanoparticle deposition process, which explains our observations. During the fabrication of monolayer crystals for nanosphere lithography, I developed a variation of the technique of convective self-assembly, where the drying meniscus is restricted by a straight-edge located approximately 100 μM above the substrate adjacent to the drying zone. This technique can yield colloidal crystals at roughly twice the growth rate compared to the standard technique. I attribute this to different evaporation rates in the thin wet films in the two cases. I also found that the crystal growth rate depends strongly on the ambient relative humidity. Finally, dithiocarbamate (DTC)-grafted polymers were synthesized and employed to functionalize surfaces of Au nanopartciles. PAH-DTC shows greater stability in different environments than PEI-DTC. I also investigated the stability of PAH-DTC coated particles in suspensions with UV-Vis spectroscopy and autotitration. The covalently bonded PAH-DTC enhances the colloidal stability of the Au nanoparticles and enables subsequent ISAM film deposition onto the particles.
Ph. D.

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Wang, Feng. "Modes, Excitation and Applications of Plasmonic Nano-apertures and Nano-cavities". Kent State University / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=kent1348588159.

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Robinson, Jendai E. "Fabrication and Characterization of Plasmonic and Electrochemical Devices Towards Sensing Applications". University of Cincinnati / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1490351933726863.

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Kalinic, Boris. "Synthesis and characterization of plasmonic nanostructures with controlled geometry for photonic applications". Doctoral thesis, Università degli studi di Padova, 2014. http://hdl.handle.net/11577/3423850.

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The purpose of the present thesis is the study of the interaction of plasmonic and pre-plasmonic nanostructures with an emitter in close proximity. The investigation was carried out following different approaches but always with the aim of inserting the experimental results in the frame- work of new or existing theoretical models in order to better understand the photophysical nature of the interaction. To this aim in the framework of this thesis different nanoarchitectures have been synthesised and coupled to Er-doped silica layers. The choice of Erbium as emitting source was driven by the great technological importance of this rare earth in photonics and optoelectronics, connected to the characteristic emission at 1540 nm that matches the window of minimum transmission loss for silica. For this reason the first step of the research activity was devoted to the optimization of the Erbium photoluminescent properties in silica. When an emitter is placed near an interface, its optical properties will be modified. To describe this variation different contributions have to be taken into account: the variation of the local density of state due to the reflection from the interface, the coupling of the emitted radiation with propagating surface plasmons on the metal-dielectric interface and the dissipation in the overlayer. All these aspects have been studied in detail for different overlayer materials demonstrating that the strong control of the excited state lifetime of the emitter can be obtained by tailoring the dielectric properties of the overlayer and the separation distance from the interface. Nanostructuring the overlayer offers further opportunities for changing the optical properties of a nearby emitter. Among different plasmonic nanostructures, nanohole arrays (NHAs) can represent the ideal candidate for this purpose due to their extraordinary optical transmission (EOT): at specific frequencies determined by the hole periodicity, the light transmitted through the NHA is orders of magnitude higher than the one predicted with the classical diffraction theory. When the EOT peak was tailored with the emission wavelength of the emitter strong plasmonic coupling was demonstrated, leading to lifetime shortening with almost no dissipation in the overlayer. The improvement of the optical performances of an emitter can be obtained not only acting on the decay from the excited state but also increasing the excitation efficiency. For this purpose, an interesting possibility that has been explored is the sensitization by of ultra-small molecular-like metal nanoclurters (NCs) produced by ion implantation. Noble metal NCs can indeed efficiently absorb light through broad-band interband transitions and transfer energy to a nearby emitter, acting as efficient nanoantennae for excitation of the emitter. Such interaction leads to the increase of the effective excitation cross-section by several orders of magnitude. Finally, all the obtained results allowed the development of predictive models that can be used in the design of novel devices for different photonic applications
Lo scopo del presente lavoro di tesi è l’analisi dell’interazione di nanostrutture plasmoniche e pre-plasmoniche con un emettitore. Lo studio è stato condotto seguendo diversi approcci, ma sempre con il fine di confrontare i risultati sperimentali con modelli teorici sia già noti che nuovi, in modo da comprendere appieno la natura foto-fisica dell’interazione. In questo senso nell’ambito della presente tesi diverse nano-architetture sono state sintetizzate ed accoppiate con film sottili di silice drogata con erbio. La scelta dell’erbio come emettitore è stata dettata dalla sua grande importanza tecnologica della terra rara nella fotonica e nell’optoelettronica, associata alla caratteristica emissione radiativa a 1540nm, che si trova nella finestra di minimo assorbimento ottico della silice. Per questa ragione il primo passo dell’attività di ricerca è stato volto all’ottimizzazione delle proprietà di fotoluminescenza dello ione erbio in silice. Quando un emettitore è posto in prossimità di un film sottile le sue proprietà ottiche vengono modificate. Per descrivere tale variazione è necessario tenere conto di contributi differenti: la variazione della densità locale degli stati dovuta alla riflessione all’interfaccia, l’accoppiamento della radiazione emessa con plasmoni di superficie propaganti sull’interfaccia metallo-dielettrico e infine la dissipazione nel film. Tutti questi aspetti sono stati studiati in dettaglio per film di diversi materiali, dimostrando che un ottimo controllo sul tempo di vita dello stato eccitato può essere ottenuto agendo sulle proprietà dielettriche del film e sulla distanza di separazione tra l’emettitore e l’interfaccia. La nanostrutturazione del film può offrire ulteriori opportunità nella modifica delle proprietà ottiche di un emettitore. Tra le diverse nanostrutture plasmoniche, i nanohole arrays (NHAs) possono essere visti come i candidati ideali per questo scopo grazie alla loro trasmissione ottica straordinaria (EOT): a determinate lunghezze d’onda definite dalla periodicità dei buchi e dalle proprietà dielettriche dei materiali coinvolti, la luce trasmessa attraverso il NHA è ordini di grandezza più grande rispetto a quella predetta dalla teoria classica della diffrazione. Quando il picco della EOT è risonante con la lunghezza d’onda di emissione dell’emettitore, è stato dimostrato un forte accoppiamento plasmonico che porta ad un marcato accorciamento del tempo di vita nella quasi assenza di dissipazione nella nanostruttura. Il miglioramento delle proprietà ottiche di un emettitore può essere ottenuto non solamente agendo sulla parte emissiva del processo, ma anche aumentando la probabilità di eccitazione. A questo scopo, una possibilità interessante è offerta dalla sensitizzazione da aggregati metallici ultra-piccoli ottenuti per impiantazione ionica. Cluster di metalli nobili composti da 10–20 atomi possono infatti assorbire efficientemente la radiazione di eccitazione attraverso transizioni interbanda e trasferire l’energia a un emettitore posto nelle vicinanze, agendo in questo modo da efficienti nanoantenne. Tale interazione può portare ad un aumento della sezione d’urto di eccitazione efficace di diversi ordini di grandezza. Infine, tutti questi risultati hanno permesso lo sviluppo di modelli predittivi che possono essere utilizzati nella progettazione di nuovi dispositivi per diverse applicazioni fotoniche

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Gordel, Marta. "Synthèse, études optiques et fonctionnalisation de nanoparticules plasmoniques pour des applications biologiques". Thesis, Université Paris-Saclay (ComUE), 2015. http://www.theses.fr/2015SACLN020.

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Les recherches décrites dans ce travail appartiennent à une branche de la science relativement jeune et interdisciplinaire, la nanophotonique. Les projets réalisés avaient pour objectif de décrire les phénomènes qui apparaissent lors de l’irradiation par un faisceau lumineux d’un matériau restreint à la dimension de quelques nanomètres à quelques centaines de nanomètres. Les phénomènes qui ont été examinés sont la génération d’absorption, de dispersion et d’émission fluorescente ainsi que le renforcement d’émission fluorescente et le renforcement du champ électromagnétique à une échelle plus petite que la limite de diffraction restreignant l’optique classique. Dans cette thèse, j’ai profité de nouvelles propriétés de la matière générées quand les dimensions sont réduites à l’échelle nanométrique (10-9 m). Elles se distinguent significativement des propriétés classiques qui caractérisent un matériau de plus grandes dimensions. Le changement de propriétés résulte de la limitation spatiale de la structure du nuage d'électrons et de l’augmentation du rapport entre la surface du matériau et son épaisseur. 23 Les particules plasmoniques, largement décrites dans ce travail, en sont un excellent exemple puisque leurs colloïdes possèdent une section efficace d'absorption très importante dans le domaine visible. Un colloïde peut présenter des couleurs différentes en fonction des formes, des dimensions et de la composition des particules qui le constituent, contrairement à une surface métallique qui ne doit son aspect qu'à la réflexion presque totale de la lumière visible et au lustre métallique. À l’échelle nanométrique, nous avons affaire à la résonance plasmonique de surface, un phénomène qui ouvre la porte à la manipulation, à la modification et au renforcement du champ électromagnétique autour de la nanostructure métallique. La possibilité de concentrer la lumière autour d’une nanoparticule au-dessous de la limite de diffraction a trouvé un bon nombre d’applications, dont la microscopie en champ proche, la spectroscopie Raman exaltée de surface (ang. Surface-enhanced Raman spectroscopy, SERS), la théranostique , la production de lecteurs de carte mémoire ou de cellules photovoltaïques. Les recherches décrites dans ce travail ont un caractère interdisciplinaire, elles améliorent nos connaissances dans le domaine de la synthèse de nanostructures plasmoniques, et des méthodes de séparation permettant d'obtenir des colloïdes qui contiennent des nanoparticules presque monodispersives. La méthode de synthèse d'un nouveau métamatériau, produit lors du transfert des nanobâtonnets d’or de l’eau à l’isopropanol, a aussi été présentée dans cette thèse. Par ailleurs, ces recherches ont montré une forte exaltation du champ électromagnétique parmi les nanoparticules. J’ai aussi dénoté une application potentielle de ce matériau en tant que substrat pour la détection de biomolécules. En outre, j’ai préparé des nanocoques d’or largement stables et dont l’épaisseur de dorure est contrôlée. À l’aide de la technique Z-scan, j’ai fait la mesure des propriétés non-linéaires des nanocoques d’or et je les ai comparées avec celles des nanobâtonnets d’or et de colorants organiques en indiquant une application possible. J’ai discuté aussi d'une nouvelle méthode de biofonctionnalisation des nanobâtonnets d’or qui m’a permis de créer un marqueur afin de visualiser des cellules vivantes. Il est aussi possible de convertir l’énergie lumineuse en énergie thermique par le biais des nanostructures plasmoniques, ce qui pourrait trouver d’autres applications intéressantes dans les recherches en théranostique
This dissertation shows the experimental results, which I strongly believe prove the possibility of application the proposed bioprobe in theranostics treatment. The advantages and disadvantages of the probe were discussed on the basis of imaging of cancer cells, toxicity and fluorescent efficiency. It is important to mention that the process of synthesis of the biomarker was controlled on each step, starting from the selection of appropriate size and shape of the core, through optical characterization, effective way of biofunctionalization and finally application in cell visualization.At first, I presented an improved method of separation of distinct shapes of gold nanoparticles from a heterogeneous mixture. The method of centrifugation in a glucose density gradient was applied in order to get homogenous fractions. The procedure of sample preparation, centrifugation and collection of the separated nanoparticles is described. Moreover, I discussed the synthesis with and without Ag+ ions added to the growth solution.Then, I had a closer look on transferring procedure of the NRs from water into IPA solvent, which induce self-organization of the nanoparticles. Optical characterization as well as recorded ATR spectra gave the foundations to understanding of the assembly process taking place. Additionally the work is enriched with the theoretical calculations indicating that individual self-assembled nanostructures show strong light polarization dependent properties. The electric field localized in the gap between NRs is estimated to be enhanced over 350 fold.In the next part of my thesis I have performed a systematic and quantitative description of the interactions of NRs with light (femtosecond laser pulses, 130 fs, 800 nm) in order to characterize the optical properties and design NRs with specific functionalities. In this work I focused on the investigation of structural changes of the NRs and the parameters influencing the reshaping, like surface modification using sodium sulfide, laser power and the position of the longitudinal surface plasmon resonance band (l-SPR) with respect to the laser wavelength.In the next part of the thesis I have quantified the probability of simultaneous absorption of two photons by plasmonic nanoparticles: gold nanorods and gold nanoshells, and by several dye molecules, by using the open-aperture Z-scan technique available in the laboratory at WUT in Poland. At first, I started from fabrication of stable and highly monodisperse NSs suspensions in water, with a varying degree of gold coverage. Then, the NLO properties of the nanoshells were quantified in terms of the two-photon absorption coefficient (α2), the nonlinear refractive index (n2), and the saturation intensity for one-photon absorption (Isat), which are extensive quantities. Then I calculated the two-photon absorption cross-section (σ2) taken per nanoparticle, which was also interpreted in terms of the merit factor σ2/M (where M is the molar mass of the nanoparticle), the quantity suitable for comparisons with other types of nonlinear absorbers.Finally, in the last chapter I have combined the results and knowledge from all previously described experiments in order to propose a new bioprobe. The probe is based on NR functionalized by DNA strand with attached fluorophore. The distance between gold surface and dye is selected in a such way as to maximize the fluorescent emission. The viability tests show low toxicity for cells and high compatibility. I showed that biofunctionalized NRs can provide fluorescent labeling of cancer cells and enable effective photothermal therapy. This is one of the first demonstrations of coupling a bioimaging application to a cancer therapy application using NRs targeted against a clinical relevant biomarker. I hope that the future studies will extend the in vitro concept demonstrated here to in vivo animal experiments

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Doherty, Matthew David. "Plasmonic nano-antenna arrays for surface enhanced Raman spectroscopy and other applications". Thesis, Queen's University Belfast, 2013. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.601361.

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On sub-wavelength scales, photon-matter interactions are limited by diffraction. Electromagnetic radiation propagating in free space - or far-field radiation - can be coupled into the surface plasmonpolaritons of nanostructured metallic surfaces in order to overcome this limitation. The distribution of electromagnetic energy in the near-field of these structures can be controlled by altering their geometry, dielectric environment and composition. Hence, surface plasmon polaritons allow electromagnetic radiation to be effectively utilized and controlled on the nanoscale. In this thesis a detailed study of the complex relationship between the electromagnetic near-field and far-field responses of 'real' nanostructured metallic surfaces is presented. The near-field and far-field responses are specified in terms of surface enhanced Raman scattering enhancement factor (SERS EF) spectra and optical extinction respectively. First, it is shown that in the far-field gold nanorod and nanotube array substrates exhibit two distinct localized surface plasmon-polariton resonances (LSPRs): a longitudinal and transverse mode. These modes are demonstrated both experimentally and theoretically, and a potential application of gold nanorod substrates as ultrathin absorbers is outlined. The near-field properties of these arrays are then studied, revealing the existence of a third type of LSPR: the cavity mode. The presence of this mode is confirmed using a combination of SERS EF spectra, electron microscopy and electromagnetic modelling. The cavity mode simultaneously has the largest impact on the near-field behaviour (as observed through the SERS EF) and the weakest optical interaction: it has a "near-field type" character. Conversely, the transverse and longitudinal modes have a significant impact on the far-field behaviour, but very little impact on SERS: they have a "far-field type" character. Based on this understanding of the contrasting character of the three LSPRs there follows a clear illustration and explanation of the non-correlation between the SERS EF spectra and the optical response, and some key consequences of this are described and demonstrated

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Hutter, Tanya. "Plasmonic and photonic nano-structures for applications in SERS and chemical sensing". Thesis, University of Cambridge, 2013. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.648334.

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Ravi, Aruna Subramanian. "Plasmonic Resonances for Spectroscopy Applications using 3D Finite-Difference Time-Domain Models". The Ohio State University, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=osu1483634449517314.

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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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Campbell, Sawyer Duane. "Studies of Passive and Active Plasmonic Core-Shell Nanoparticles and their Applications". Diss., The University of Arizona, 2013. http://hdl.handle.net/10150/293420.

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Coated nanoparticles (CNP) are core-shell particles consisting of differing layers of epsilon positive (EP) and epsilon negative (ENG) materials. The juxtaposition of these EP and ENG materials can lead to the possibility of coupling incident plane waves to surface plasmon resonances (SPR) for particles even highly subwavelength in size. We introduce standard models of the permittivities of the noble metals used in these CNPs, and propose corrections to them based on experimental data when their sizes are extremely small. Mie theory is the solution to plane wave scattering by spheres and we extend the solution here to spheres consisting of an arbitrary number of layers. We discuss the resonance behaviors of passive CNPs with an emphasis on how the Coated nanoparticles (CNP) are core-shell particles consisting of differing layers of epsilon positive (EP) and epsilon negative (ENG) materials. The juxtaposition of these EP and ENG materials can lead to the possibility of coupling incident plane waves to surface plasmon resonances (SPR) for particles even highly subwavelength in size. We introduce standard models of the permittivities of the noble metals used in these CNPs, and propose corrections to them based on experimental data when their sizes are extremely small. Mie theory is the solution to plane wave scattering by spheres and we extend the solution here to spheres consisting of an arbitrary number of layers. We discuss the resonance behaviors of passive CNPs with an emphasis on how the resonance wavelength can be tuned by controlling the material properties and radii of the various layers in the configuration. It is demonstrated that these passive CNPs have scattering cross sections much larger than their geometrical size, but their resonance strengths are attenuated because of the inherent losses in the metals. To overcome this limitation, we show how the introduction of active material into the CNPs can not only overcome these losses, but can actually lead to an amplification of the scattering of the incident field. We report several optimized active CNP designs, including ones based on quantum dot gain media and study their performance characteristics with particular attention to the effect of the location of the gain material on the performance of these designs. We investigate the ability to control the scattered field directivity of the CNPs in both their far- and near-field regions and propose designs with minimal backscattering and those emulating macroscopic nanojets. We compare data generated by initial efforts to experimentally prepare CNPs and compare against analytical and numerical simulation results. Finally, we suggest a variety of interesting future research directions. resonance wavelength can be tuned by controlling the material properties and radii of the various layers in the configuration. It is demonstrated that these passive CNPs have scattering cross sections much larger than their geometrical size, but their resonance strengths are attenuated because of the inherent losses in the metals. To overcome this limitation, we show how the introduction of active material into the CNPs can not only overcome these losses, but can actually lead to an amplification of the scattering of the incident field. We report several optimized active CNP designs, including ones based on quantum dot gain media and study their performance characteristics with particular attention to the effect of the location of the gain material on the performance of these designs. We investigate the ability to control the scattered field directivity of the CNPs in both their far- and near-field regions and propose designs with minimal backscattering and those emulating macroscopic nanojets. We compare data generated by initial efforts to experimentally prepare CNPs and compare against analytical and numerical simulation results. Finally, we suggest a variety of interesting future research directions

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Shahine, Issraa. "A chemical route to design plasmonic-semiconductor nanomaterials heterojunction for photocatalysis applications". Thesis, Université de Lorraine, 2019. http://www.theses.fr/2019LORR0105/document.

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L’ingénierie de nanomatériaux hybrides semi-conducteurs/plasmoniques représente une technologie durable en raison de l’efficacité parfaite du couplage pour améliorer, rénover et enrichir les propriétés des composants intégrés. Ce couplage a pour résultat la variation des propriétés fonctionnelles du système, grâce auquel les plasmons de surface générés par les métaux peuvent améliorer la séparation des charges, l’absorption de la lumière et la luminescence du semi-conducteur. Ce phénomène permet de fortes interactions avec d'autres éléments photoniques tels que les émetteurs quantiques. Ces fonctionnalités aux multiples facettes découlent de l'interaction synergique exciton-plasmon entre les unités liées. Ainsi, les nanomatériaux hybrides conviennent à diverses applications, notamment : conversion de l'énergie solaire, dispositifs optoélectroniques, diodes électroluminescentes (LED), photocatalyse, détection biomédicale, etc. Les nanostructures Au-ZnO suscitent un intérêt croissant dans ces applications où le couplage de ZnO à de nanoparticules d’or (GNPs) favorise la réponse du système dans le domaine du visible grâce à leur résonance plasmon de surface (SPR). En fonction de la taille de deux nanomatériaux, de la distance qui les sépare et leurs rapports massiques dans un échantillon, les propriétés des particules hybrides peuvent varier. Dans ce contexte, nous nous sommes concentrés sur la construction de nano-cristaux (NCs) de ZnO purs de dimensions contrôlables, puis incorporés dans des solutions de GNPs par une simple voie chimique. Ce travail est divisé en deux parties : la première consiste à effectuer une synthèse de nanocristaux de ZnO (NCs) purs présentant d'excellentes propriétés de photoluminescence dans l’UV. Ceci a été réalisé par une synthèse à basse température, aboutissant à des structures rugueuses et amorphes. La synthèse a été suivie d'un traitement post-thermique afin de cristalliser les nanoparticules obtenues. Une étude structurale et optique poussée a été établie à la suite de la synthèse (SEM, TEM, DRX, photoluminescence). Les activités photocatalytiques des ZnO NCs ont été étudiées en mesurant leur capacité à dégrader le bleu de méthylène (MB). De plus, la relation entre les structures en ZnO, la luminescence et les propriétés photocatalytiques a été explorée en détail. Dans la deuxième étape, les ZnO NCs obtenus ont été couplés ajoutés à des nanoparticules d'or de tailles et fractions volumiques variables. Le rôle effectif des GNPs concernant leur morphologie, leur contenu et leur effet SPR sur la photoémission des nanostructures de ZnO est souligné par le transfert de charge et / ou d'énergie entre les constituants du système hybride. De plus, l’activité photocatalytique du système hybride a été examinée. Comme débouché et perspective de ce travail de thèse, l'intégration des ZnO NC dans une couche nanoporeuse de polymère (PMMA) a été réalisée et caractérisée afin d'obtenir un substrat de large surface à base de ZnO. Les ZnO NCs assemblés dans du PMMA pourraient être des substrats prometteurs en tant que catalyseurs pour la croissance de nanofils de ZnO, de nanomatériaux métalliques et de matériaux hybrides
Hybrid heterojunctions composed of semiconductors and metallic nanostructures have perceived as a sustainable technology, due to their perfect effectiveness in improving, renovating, and enriching the properties of the integrated components. The cooperative coupling results in the variation of the system’s functional properties, by which the metal-generated surface plasmon resonance can enhance the charge separation, light absorption, as well as luminescence of the semiconductor. This phenomenon enables strong interactions with other photonic elements such as quantum emitters. These multifaceted functionalities arise from the synergic exciton-plasmon interaction between the linked units. Thereby, hybrid systems become suitable for various applications including: solar energy conversion, optoelectronic devices, light-emitting diodes (LED), photocatalysis, biomedical sensing, etc. Au-ZnO nanostructures have received growing interest in these applications, where the deposition of gold nanoparticles (GNPs) promotes the system’s response towards the visible region of the light spectrum through their surface plasmon resonance (SPR). Based on a specific size and purity of ZnO nanostructures, as well as the GNPs, and a definite inter-distance between the nanoparticles, the properties of the ZnO nanostructures are varied, especially the photoemission and photocatalytic ones. In this context, we have focused on the construction of size-tunable ZnO nanocrystals (NCs), then incorporated into GNPs solutions using a simple chemical way. This work is divided into two parts: the first is to perform synthesis of pure ZnO NCs having excellent UV photoluminescence. This was achieved through a low-temperature aqueous synthesis, resulting in rough and amorphous structures. The synthesis was followed by a post-thermal treatment in order to crystallize the obtained particles. The synthesis was followed by structural and optical studies (SEM, TEM, XRD, photoluminescence). The photocatalytic activities of ZnO NCs were studied through tailoring their ability to degrade the methylene blue (MB) dye. In addition, the relationship between ZnO structures, luminescence, and photocatalytic properties was explored in details. In the second step, the obtained ZnO NCs were added to gold nanoparticles of various sizes and volume fractions. The effective role of GNPs concerning their size, amount, and their capping molecule on the photoemission of the ZnO nanostructures was emphasized through the charge and/or energy transfer between the constituents in the hybrid system. In the same way, the systems photocatalytic activities were examined after coupling ZnO to GNPs. Further advancement in the integration of the ZnO NCs into PMMA polymer layers was featured in order to obtain large area template of homogenous ZnO properties. The PMMA-assembled ZnO nanoparticles could be promising substrates as catalysts for growing ZnO nanowires, metallic nanoparticles and hybrid nanomaterials

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Joshi, Bhuwan. "DESIGN AND STUDY OF PLASMONIC NANOSTRUCTURES FOR APPLICATIONS IN BIOLOGICAL DETECTION AND PHOTONICS". Kent State University / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=kent1324762602.

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Zgrabik, Christine Michelle. "Wide Tunability of Magnetron Sputtered Titanium Nitride and Titanium Oxynitride for Plasmonic Applications". Thesis, Harvard University, 2016. http://nrs.harvard.edu/urn-3:HUL.InstRepos:33493259.

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Transition metal nitrides have recently garnered much interest as alternative materials for robust plasmonic device architecture including potential applications in solar absorbers, photothermal medical therapy, and heat-assisted magnetic recording. Titanium nitride (TiN) is one such potential candidate. One advantage of the transition metal nitrides is that their optical properties are tunable according to the deposition conditions. The controlled achievement of tunability, however, is also a challenge. Although the formation of TiN has been the subject of numerous previous studies, a thorough analysis of the deposition parameters necessary to form metallic TiN films optimized for plasmonic applications had not been demonstrated. Similarly, such TiN films had not been subjected to detailed optical measurements which could be used in FDTD device simulations to optimize plasmonic device designs. To be able to design, simulate and build robust and optimal device structures, in this work a systematic and thorough examination of the effect of varied substrates, temperatures, and reactive gas compositions on magnetron sputtered TiN was conducted. In addition, the effects of application of an additional substrate bias were studied. The resulting optical properties at visible to near-infrared frequencies were the focus of this thesis. The optical properties of each film were measured via spectroscopic ellipsometry with more "metallic” films demonstrating a larger negative value of the real part of the permittivity. These optical measurements were correlated with both the films’ deposition conditions and microstructural measurements including x-ray photoelectron spectroscopy (XPS), x-ray diffraction (XRD), and transmission electron microscopy (TEM) measurements; the different deposition conditions resulted in TiN and TiOxNy films with widely tunable optical responses. By sputtering under different conditions, the value of the real part of the permittivity was tuned from small positive values, through small and moderate negative values, and finally all of the way to large negative values which are comparable to those measured in gold. It was determined that both the chemical composition as well as the film crystallinity had a significant effect on the resulting properties with the most metallic films in general exhibiting a Ti:N ratio close to 1:1, low oxygen incorporation, more N bound as TiN rather than in oxynitride form, and better crystallinity. Increased substrate temperature in general increased the metallic character while application of a substrate bias reduced crystalline order, however also reduced oxygen incorporation and allowed for deposition of metallic TiN at room temperature. The close lattice match of TiN and MgO allowed for heteroepitaxial growth on this substrate under carefully controlled conditions. Finally, to demonstrate the viability of the optimized TiN thin films for plasmonic applications, three benchmark plasmonic structures were simulated using the measured, optimized optical properties including a plasmonic grating coupler, infrared nanoantennas, and a nanopyramidal array. The devices were successfully fabricated and preliminary measurements show promise for plasmonic applications for example in solar conversion and photothermal medical therapy.
Engineering and Applied Sciences - Applied Physics

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Ghasemi, Rasta. "Métamatériaux pour l’infrarouge et applications". Thesis, Paris 11, 2012. http://www.theses.fr/2012PA112292/document.

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Les métamatériaux sont des composites artificiels présentant des propriétés électromagnétiques qu’on ne trouve pas dans la nature. Malgré des développements spectaculaires durant la dernière décennie, le potentiel de ces structures aux longueurs d’ondes optique n’est pas encore clairement défini en raison de problèmes technologiques et de contraintes physiques telles que les pertes dans les métaux entrant dans la composition des métamatériaux. Dans notre thèse, nous montrons que les métamatériaux ont des propriétés très favorables dans le contexte de l’optique intégrée dans le proche infrarouge. Nous avons développé une stratégie pour incorporer des métamatériaux dans des circuits photoniques qui n’absorbent que très peu d’énergie. Pour cela, nous ne faisons pas directement agir l’ensemble du mode guidé avec les métamatériaux, mais seulement une composante évanescente à l’extérieur du guide. Pour réaliser un tel adaptateur ou d’autres fonctionnalités, il importe de déterminer quelle géométrie de métamatériaux est la plus favorable aux applications infrarouges. Nous proposons d’utiliser des structures à base de fils d’or empilés couche sur couche. A l’aide de simulations numériques et d’expériences en espace libre, nous montrons qu’il est possible d’obtenir toute une gamme de réponses optiques en contrôlant le couplage entre les différents niveaux de fils, c'est-à-dire en ajustant la distance entre les fils ainsi que leur alignement. En particulier, nous avons réussi à contrôler séparément la réponse électrique et magnétique de nos structures, ce qui offre une flexibilité de conception qui ne se rencontre pas dans les métamatériaux proposés jusqu’à présent
Metamaterials are artificial composites with electromagnetic properties not found in nature. Although the development of metamaterials has experienced a tremendous growth over the past few years, their potential at optical wavelengths is not clearly established due to technological and physical constraints such as high material losses in this spectral range. Here we show that metamaterials have a great potential in the context of integrated optics in the near infrared. We developed a strategy to incorporate metamaterials in photonic circuits with minimal absorption losses. Our approach relies on making the guided modes interact with the metamaterials only through the evanescent tail outside the waveguide. To achieve such an adaptor and other functionalities, it is important to know what is the best geometry for near-infrared applications. We propose to use metamaterials based on multi-layers of Au cut wires. With numerical simulations and experiments, we show that it is possible to create a wide range of optical properties by controlling the interaction between the wires, i.e. by adjusting the distance between the wires and their alignment. In particular we were able to demonstrate

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38

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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Farcau, Cosmin [Verfasser]. "Ordered Plasmonic Nanostructures: from Fabrication to Relevant Applications in Optical Spectroscopy and Sensing / Cosmin Farcau". Munich : GRIN Verlag, 2015. http://d-nb.info/1097463818/34.

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Bertorelle, Fabrizio. "Magneto-plasmonic nanostructures based on laser ablated nanoparticles of Au and FeOx for nanomedicine applications". Doctoral thesis, Università degli studi di Padova, 2016. http://hdl.handle.net/11577/3422266.

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In the last years, gold and iron oxide nanoparticles have received an increasing interest in nanomedicine and biotechnology thanks to their properties. Gold nanoparticles (AuNPs) are biocompatible and possess useful optical properties that make them a powerful imaging tool using, for example, SERS spectroscopy. On the other hand, iron oxide nanoparticles (FeOxNPs, in particular those made of magnetite) are interesting because of their magnetic properties. Combining gold and iron oxide nanoparticles in a unique system, one obtains a magneto-plasmonic material in which the characteristics properties of the two nanoparticles are present. The use of magneto-plasmonic nanostructured materials in nanomedicine is a quite young research topic and one of the reasons is the elaborated synthesis often required. Several passages are needed also for the purification of these nanosystem from chemicals used during synthesis, which is a crucial point when the final application is in nanomedicine or nanobiology. In this work we will show the synthesis of two magneto-plasmonic systems made of gold and iron oxide nanoparticles. AuNPs and FeOxNPs are synthetized with the laser ablation synthesis in solution (LASiS) method. LASiS is a green chemistry method, which allows to obtain chemical-free and stable nanoparticles in water solution. With LASiS, purification passages are unnecessary or reduced to a minimum and no chemicals that could interfere in biological environment are present. In chapter 2 it will be reported the synthesis of gold and iron oxide nanoclusters (AuFeOxNC) in which the aggregation between particles is performed without the use of chemicals, but exploiting the surface charges of nanoparticles. The use of such nanoclusters in cells guiding and sorting and imaging will be also shown. In chapter 3, the synthesis of another magneto-plasmonic system in which AuNPs and FeOxNPs are arranged in a core-shell-satellite structure, is reported. Also in this case, purification passages are reduced thanks to the laser ablation synthesis. This system is conjugated with an antibody and shows high performance in immunomagnetic sorting and photothermal treatment of cancer cells. The arguments developed in the thesis are introduced in the first chapter.
Negli ultimi anni, nanoparticelle di oro e ossido di ferro hanno ricevuto un interesse crescente in campi come la nanomedicina e la biotecnologia grazie alle loro proprietà. Le nanoparticelle di oro (AuNPs) sono biocompatibili e possiedono utili proprietà ottiche che le rendono un potente strumento di imaging usando, per esempio, la spettroscopia SERS.Le nanoparticelle di ossido di ferro (FeOxNP, in particolare quelle di magnetite) sono interessanti a causa delle loro proprietà magnetiche. Combinando i due tipi di particelle in un unico sistema si ottiene un materiale magneto-plasmonico, nel quale si manifestano le proprietà di entrambe le nanoparticelle. L'uso di materiali magneto-plasmonici in nanomedicina è un campo di ricerca abbastanza giovane e uno dei motivi è la sintesi elaborata che spesso questi materiali richiedono. Durante la sintesi sono necessari diversi passaggi di purificazione dalle sostanze chimiche impiegate, passaggi che sono fondamentali quando l'applicazione finale è la nanomedicina o la nanobiologia.In questa tesi mostreremo la sintesi di due sistemi magneto-plasmonici composti da nanoparticelle di oro e ossido di ferro. AuNPs e FeOxNPs sono sintetizzate con il metodo dell'ablazione laser in soluzione (LASiS). Con l'ablazione laser i passaggi di purificazione non sono necessari e non sono presenti sostanze chimiche che possono interferire in ambiente biologico. Nel capitolo due della tesi mostreremo la sintesi di nanocluster di nanoparticelle di oro e ossido di ferro nei quali i due tipi di particelle sono aggregate senza l'utilizzo di sostanze chimiche. Questi nanocluster saranno utilizzati per guidare magneticamente cellule in soluzione, per la selezione di cellule e imaging. Nel capitolo tre viene riportata la sintesi di un altro sistema magneto-plasmonico in cui AuNPs e FeOxNPs sono arrangiate in una struttura di tipo core-shell-satellite. Anche in questo caso i passaggi di purificazione sono ridotti grazie all'utilizzo dell'ablazione laser. Questo sistema viene poi completato coniugando un anticorpo e mostra ottime performance nella selezione immunomagnetica e nel trattamento fototermico di cellule cancerose. Gli argomenti trattati nella tesi sono introdotti nel primo capitolo.

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Zon, Vera [Verfasser], Gerhard [Akademischer Betreuer] Abstreiter i Friedrich C. [Akademischer Betreuer] Simmel. "Nanoparticle Structures for Plasmonic Applications / Vera Zon. Gutachter: Friedrich C. Simmel ; Gerhard Abstreiter. Betreuer: Gerhard Abstreiter". München : Universitätsbibliothek der TU München, 2013. http://d-nb.info/103782072X/34.

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Hajfathalian, Maryam. "SUBSTRATE-BASED NOBLE-METAL NANOMATERIALS: SHAPE ENGINEERING AND APPLICATIONS". Diss., Temple University Libraries, 2017. http://cdm16002.contentdm.oclc.org/cdm/ref/collection/p245801coll10/id/431697.

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Mechanical Engineering
Ph.D.
Nanostructures have potential for use in state-of-the-art applications such as sensing, imaging, therapeutics, drug delivery, and electronics. The ability to fabricate and engineer these nanoscale materials is essential for the continued development of such devices. Because the morphological features of nanomaterials play a key role in determining chemical and physical properties, there is great interest in developing and improving methods capable of controlling their size, shape, and composition. While noble nanoparticles have opened the door to promising applications in fields such as imaging, cancer targeting, photothermal treatment, drug delivery, catalysis and sensing, the synthetic processes required to form these nanoparticles on surfaces are not well-developed. Herein is a detailed account on efforts for adapting established solution-based seed-mediated synthetic protocols to structure in a substrate-based platform. These syntheses start by (i) defining heteroepitaxially oriented nanostructured seeds at site-specific locations using lithographic or directed-assembly techniques, and then (ii) transforming the seeds using either a solution or vapor phase processing route to activate kinetically- or thermodynamically-driven growth modes, to arrive at nanocrystals with complex and useful geometries. The first series of investigations highlight synthesis-routes based on heterogeneous nucleation, where templates serve as nucleation sites for metal atoms arriving in the vapor phase. In the first research direction, the vapor-phase heterogeneous nucleation of Ag on Au was carried out at high temperatures, where the Ag vapor was sourced from a sublimating foil onto adjacent Au templates. This process transformed both the composition and morphology of the initial Au Wulff-shaped nanocrystals to a homogeneous AuAg nanoprism. In the second case, the vapor-phase heterogeneous nucleation of Cu atoms on Au nanocrystal templates was investigated by placing a Cu foil next to Au templates and heating, which caused the Cu atoms from the foil to sublimate from the foil and heterogeneously nucleation on the surface of the immobilized Au seeds. This process caused the composition and morphology of the Au Wulff-shape to transform into a homogeneous AuCu nanotriangle. Lastly, we characterized the morphological features and composition, optical properties, and also the catalytic and photocatalytic performance toward hydrogenation of 4-nitrophenolate. The second series of investigations highlight synthetic routes utilizing competencies of substrate-based techniques with colloidal chemistry. We have demonstrated two substrate-based syntheses yielding bimetallic nanostructures where shape control was achieved through (i) facet-selective capping agents and (ii) additive and subtractive process. In the first case a citrate-based cubic structure has been synthesized in the presence or absence of ascorbic acid and the role of each has been considered in shape control. Reactions were carried out in which Ag+ ions were reduced onto substrate-immobilized Ag, Au, Pd, and Pt seeds. It was discovered that for syntheses lacking ascorbic acid, citrate acts as both the capping and the reducing agent, resulting in a robust nanocube growth mode; however, when ascorbic acid was included in these syntheses, then the growth mode reverted to one that advances the octahedral geometry. The conclusion of these results was that citrate, or one of its oxidation products, selectively caps (100) facets, but where this capability was compromised by ascorbic acid. In the second case, galvanic replacement reactions have been carried out on immobilized cubic and Wulff structures to create the substrate-based nanoshells and nanocages, where the prepositioned templates were chemically transformed into hollow structures. In this novel research, Wulff-shaped templates of Au, Pt, or Pd, formed through the dewetting of ultrathin films, were first transformed into core−shell structures through the reduction of Ag+ ions onto their surface and then further transformed through the galvanic replacement of Ag with Au. Detailed studies were provided highlighting discoveries related to (i) alloying, (ii) dealloying, (iii) hollowing, (iv) crystal structure and (vi) the localized surface plasmon resonance (LSPR). Overall, a series of synthetic strategies based on physical and chemical vapor deposition were devised and validated to achieve novel substrate- based nanomaterials with different shapes and compositions for a variety of applications such as sensing, plasmonics, catalysis, and photocatalysis. The novel research in this dissertation also takes advantage of competencies of substrate-based techniques with colloidal chemistry and, brings this rich and exciting chemistry and its associated functionalities to the substrate surface.
Temple University--Theses

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Alam, Muhammad. "Hybrid Plasmon Waveguides: Theory and Applications". Thesis, 2012. http://hdl.handle.net/1807/33902.

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The study and applications of surface plasmon polaritons (SP) – also known as plasmonics – has attracted the interest of a wide range of researchers in various fields such as biology, physics, and engineering. Unfortunately, the large propagation losses of the SP severely limit the usefulness of plasmonics for many practical applications. In this dissertation a new wave guiding mechanism is proposed in order to address the large propagation losses of the plasmonic guides. Possible applications of this guiding scheme are also investigated. The proposed hybrid plasmonic waveguide (HPWG) consists of a metal layer separated from a high index slab by a low index spacer. A detailed analysis is carried out to clarify the wave guiding mechanism and it is established that the mode guided by the HPWG results from the coupling of a SP mode and a dielectric waveguide mode. A two dimensional HPWG is proposed and the effects of various parameters on the HPWG performance are analyzed in detail. This structure offers the possibility of integrating plasmonic devices on a silicon platform. The proposed waveguide supports two different modes: a hybrid TM mode and a conventional TE mode. The hybrid TM mode is concentrated in the low index layer, whereas the conventional TE mode is concentrated in the high index region. This polarization diversity is used to design a TM- and a TE-pass polarizer and a polarization independent coupler on a silicon-on-insulator (SOI) platform. Moreover, the performance of a HPWG bend is investigated and is compared with plasmonic waveguide bends. The proposed devices are very compact and outperform previously reported designs. The application of HPWG for biosensing is also explored. By utilizing the polarization diversity, the HPWG biosensor can overcome some of the limitations of plasmonic sensors. For example, unlike plasmonic sensors, the HPWG biosensor can remove the interfering bulk and surface effects.

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Adleman, James Richard. "Plasmonic Nanoparticles for Optofluidic Applications". Thesis, 2009. https://thesis.library.caltech.edu/1719/2/james_adleman_thesis_corrected.pdf.

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This thesis discusses the application of colloidal particles to optofluidic systems. Colloidal particles can be added as a "dopant" to the liquids in these devices to provide functionality that cannot be obtained with homogenous fluids. We examine electrooptic effects in liquid suspensions asymmetric metallic nanoparticles. The theoretical optical properties of gold nanorods and noble metal nanohalfshells are computed and compared with those of actual colloidal dispersions. We discuss the design and fabrication of electro-optic waveguides utilizing these suspensions as the active material. We also study the dynamics of photothermal holograms recorded by nanosecond laser pulses in suspensions of silver nanospheres. Unexpected transients in the grating diffraction efficiency correspond to the nanoscale inhomgeneity of the colloid. Longer timescale decay can be used to measure the thermal conductivity of the liquid as predicted by the established theory of heat conduction. This technique is extended to perform spatial imaging of the thermal diffusivity of immiscible binary liquids. Gold nanosphere coated substrates for microfluidic devices are employed to enable optical actuation of fluids. Nanoparticle absorption of continuous wave laser light was used to trap air bubbles inside partially filled microfluidic channels. Light focused on the array near one side of the trapped bubble will drive a mass flow across the bubble. This evaporative bubble assisted mass transport mechanism can be operated as a pump powered by a stationary laser beam. In addition, the process efficiently separates volatile and non-volatile materials and can concentrate and purify specimens in solution.

Finally, several schemes for storing and extracting data from subwavelength volumes using spectral multiplexing of semiconductor quantum dots are explored. We demonstrate microfluidic composition and delivery of cocktails of several colors of quantum dots to act as information packets for optical storage. In addition we analyze imaging at the subwavelength level using a patterned surface of quantum dots. The theoretical performance of such a surface is compared to imaging through nanoapertures as is currently implemented in optofluidic microscopy.

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Wu, Pae. "Plasmonic Gallium Nanoparticles -- Attributes and Applications". Diss., 2009. http://hdl.handle.net/10161/1121.

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Expanding the role of plasmonics in tomorrow's technology requires a broader knowledge base from which to develop such applications today. Several limitations to the current plasmonics field limit progress to incremental advances within a narrow set of materials and techniques rather than developing non-traditional metals and flexible growth and characterization methods. The work described herein will provide an introduction to the burgeoning field of spectroscopic ellipsometry for plasmonic characterization; in particular, the power of its real-time monitoring capabilities and flexibility will be demonstrated. More importantly, a novel plasmonic metal, gallium, is investigated in detail. Critical characteristics of gallium for an array of applications include its tunability over a wide spectral range, phase stability across a wide temperature range, plasmon stability even after air exposure, and an ultra high vacuum evaporation growth process enabling simple, alloyed nanostructure development. Deeper scientific investigation of the underlying ripening mechanisms driving gallium nanoparticle formation and in concert with in situ alloying paves the way for future work contributing to the development of advanced nanostructured alloys. Finally, this work demonstrates the first example of gallium nanoparticle-enhanced Raman spectroscopy - an area craving materials innovation. While the specific application of gallium for SERS detection is interesting, the far-reaching implication lies in the demonstrated potential for plasmonic gallium nanoparticles' ultimate use in a wider variety of applications enhanced by nanoscale materials.

Dissertation

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Zhang, Ran. "Biocompatible plasmonic nanostructures for bio-imaging applications and novel functional plasmonic materials". Thesis, 2018. https://hdl.handle.net/2144/30727.

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Our work addresses a novel biocompatible plasmon-enhanced nanostructure approach based on the combination of metal nanoparticles, light emitting polymer-based nanostructures, and scalable cellulose nanofiber templates via a one-step facile electrospinning process that can easily be applied to biomedical devices. In collaboration with the Team of Prof. Lee Goldstein in the Boston University medical campus, we demonstrated light emission from small-size (below 200nm) polymer nanoparticles coupled to plasmonic nanoparticles and to light-emitting biocompatible molecules. In order to fully demonstrate the potential of our novel plasmonic nanostructures we developed Magnetic resonance imaging (MRI) reagent doped Polycaprolactone (Core)-Polyethylene glycol (shell) core-shell nanoparticles and studied their size distribution and dispersion properties in a phosphate buffered saline solution. Our materials were optimized in order to obtain no aggregation of the nanoparticles in solution. The presence of MRI reagent in nanoparticles were demonstrated via Inversion Recovery Sequences (IR) by characterizing the different T1 relaxation times. The concentration of Gd in the nanoparticles dispersion was estimated with different dilution of Gd commercial reagent as a reference. In addition, we combined facile electrospinning fabrication with top down nano-deposition and demonstrated a novel and scalable plasmonic resonant medium for rapid and reliable Raman scattering sensing of molecular monolayers and bacteria. Specifically, aided by PCA multivariate data analysis techniques, we demonstrated fingerprinting Surface Enhanced Raman Scattering (SERS) spectra of different bacteria strains (E. Coli K12, E. coli BL21 (DE3) and E. coli DH 5α) entrapped in our novel plasmonic networks. Finally, in this thesis we have also addressed the development of novel, Si-compatible and largely tunable plasmonic materials for biosensing applications in the mid-infrared spectral range and developed a novel type of transparent conductive oxide based on the Indium Silicon Oxide (ISO) material (Indium Silicon Oxide) that features enhanced surface smoothness and thermal stability compared to Indium tin oxide (ITO) and Titanium nitride (TiN) alternative plasmonic materials. In collaboration with our collaborators at Columbia University, we demonstrated the tunability of near-field plasmonic resonances from 1.8 to 5.0 μm as a function of different annealing temperature. This work provides an enabling first-step towards the development of novel Si-compatible materials with tunable plasmon resonances for metamaterials and sensing devices that operate across the infrared spectrum.
2019-07-02T00:00:00Z

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Zhen, Yurong. "Plasmonic properties and applications of metallic nanostructures". Thesis, 2013. http://hdl.handle.net/1911/72071.

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Plasmonic properties and the related novel applications are studied on various types of metallic nano-structures in one, two, or three dimensions. For 1D nanostructure, the motion of free electrons in a metal-film with nanoscale thickness is confined in its normal dimension and free in the other two. Describing the free-electron motion at metal-dielectric surfaces, surface plasmon polariton (SPP) is an elementary excitation of such motions and is well known. When further perforated with periodic array of holes, periodicity will introduce degeneracy, incur energy-level splitting, and facilitate the coupling between free-space photon and SPP. We applied this concept to achieve a plasmonic perfect absorber. The experimentally observed reflection dip splitting is qualitatively explained by a perturbation theory based on the above concept. If confined in 2D, the nanostructures become nanowires that intrigue a broad range of research interests. We performed various studies on the resonance and propagation of metal nanowires with different materials, cross-sectional shapes and form factors, in passive or active medium, in support of corresponding experimental works. Finite- Difference Time-Domain (FDTD) simulations show that simulated results agrees well with experiments and makes fundamental mode analysis possible. Confined in 3D, the electron motions in a single metal nanoparticle (NP) leads to localized surface plasmon resonance (LSPR) that enables another novel and important application: plasmon-heating. By exciting the LSPR of a gold particle embedded in liquid, the excited plasmon will decay into heat in the particle and will heat up the surrounding liquid eventually. With sufficient exciting optical intensity, the heat transfer from NP to liquid will undergo an explosive process and make a vapor envelop: nanobubble. We characterized the size, pressure and temperature of the nanobubble by a simple model relying on Mie calculations and continuous medium assumption. A novel effective medium method is also developed to replace the role of Mie calculations. The characterized temperature is in excellent agreement with that by Raman scattering. If fabricated in an ordered cluster, NPs exhibit double-resonance features and the double Fano-resonant structure is demonstrated to most enhance the four-wave mixing efficiency.

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Wu, Chihhui. "Fano-resonant plasmonic metamaterials and their applications". Thesis, 2012. http://hdl.handle.net/2152/ETD-UT-2012-08-6030.

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Manipulating electromagnetic fields with plasmonic nanostructures has attracted researchers from interdisciplinary areas and opened up a wide variety of applications. Despite the intriguing aspect of inducing unusual optical properties such as negative indices and indefinite permittivity and permeability, engineered plasmonic nanostructures are also capable of concentrating electromagnetic waves into a diffraction-unlimited volume, thus induce incredible light-matter interaction. In this dissertation, I’ll discuss about a class of plasmonic structures that exhibit the Fano resonance. The Fano resonance is in principle the interference between two resonant modes of distinct lifetimes. Through the Fano resonance, the electromagnetic energy can be trapped in the so called “dark” mode and induce strong local field enhancement. A variety of Fano resonant nanostructures ranging from periodic planar arrays to simple clusters composed of only two particles are demonstrated in this dissertation. By artificially designing the dimensions of the structures, these Fano-resonant materials can be operated over a broad frequency range (from visible to mid-IR) to target the specific applications of interest. In this dissertation, I’ll show the following research results obtained during my PhD study: (1) the double-continuum Fano resonant materials that can slow down the speed of light over a broad frequency range with little group velocity dispersion. (2) Ultra-sensitive detection and characterization of proteins using the strong light-matter interaction provided by the Fano-reonant asymmetric metamaterials. (3) Metamaterials absorbers with nearly 100 % absorbance, tunable spectral position, expandable bandwidth, and wide angle absorption. These Fano-resonant materials can have profound influences in the areas of optical signal processing, life science, bio-defense, energy harvesting and so on.
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Moura, André de Távora Vasconcelos de. "Development of Plasmonic Nanosandwiches for Biosensing Applications". Master's thesis, 2018. http://hdl.handle.net/10362/58086.

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Structures composed of two gold disks with different diameters and separated by a thin alumina layer were studied for protein biodetection. The small top disk will be used as the biosensing element since it has a shorter decay length (and thus, it has a higher sensitivity) whereas the big bottom one will give a high signal due to its bigger interaction with light. The interaction between both disks will happen through plasmon hybridisation. The samples were prepared using colloidal lithography and material deposition was made through an electron beam assisted evaporation system. A fabrication method was developed to spatially isolate the bottom disk from the sensing medium to fully exploit the small disk’s higher sensitivity. Sample’s characterisation consisted in a morphologic analysis by scanning electronic microscopy (SEM), the optical response was studied experimentally and by finite-domain time-difference (FDTD) simulations and also the electric field distribution was analysed in three types of structures. Structures with the upper disk centred relative to the lower disk and at the edge of it. The oxide’s thickness effect was studied (3 and 6 nm). The low energy peak is mainly given by a plasmonic gap dipole mode, whereas as the high energy peak is given by a contribution from a gap mode and the structure’s overall net dipole. The structure with a smaller separation and the top disk centre regarding the bottom disk was found to have a higher electric field enhancement around it and should be the one to be used as a biosensor.

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Roque, Samantha Ross Magtaan. "Anisotropic Plasmonic-Semiconductor Nanocomposites for Photocatalytic Applications". Master's thesis, 2021. https://hdl.handle.net/10216/139610.

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