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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<br>Ph.D.<br>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.<br>Temple University--Theses
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Bordley, Justin Andrew. "Cubic architectures on the nanoscale: The plasmonic properties of silver or gold dimers and the catalytic properties of platinum-silver alloys." Diss., Georgia Institute of Technology, 2016. http://hdl.handle.net/1853/55025.
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This thesis explores both the optical and catalytic properties of cubic shaped nanoparticles. The investigation begins with the sensing capabilities of cubic metal dimers. Of all the plasmonic solid nanoparticles, single Ag or Au nanocubes exhibit the strongest electromagnetic fields. When two nanoparticles are in close proximity to each other the formation of hot spots between plasmonic nanoparticles is known to greatly enhance these electromagnetic fields even further. The sensitivity of these electromagnetic fields as well as the sensitivity of the plasmonic extinction properties is important to the development of plasmonic sensing. However, an investigation of the electromagnetic fields and the corresponding sensing capabilities of cubic shaped dimers are currently lacking.
In Chapters 2-5 the optical properties of cubic dimers made of either silver or gold are examined as a function of separation distance, surrounding environment, and dimer orientation. A detailed DDA simulation of Au–Au and Ag-Ag dimers oriented in a face-to-face configuration is conducted in Chapter 2. In this Chapter a distance dependent competition between two locations for hot spot formation is observed. The effect of this competition on the sensing capabilities of these dimers is further explored in Chapters 3 and 4. This competition originates from the generation of two different plasmonic modes. Each mode is defined by a unique electromagnetic field distribution between the adjacent nanocubes.
In Chapter 4 the maximum value of the electromagnetic field intensity is investigated for each mode. Notably the magnitude of the electromagnetic field is not directly proportional to its extinction intensity. Furthermore, the sensitivity of a plasmonic mode does not depend on its extinction intensity. The sensitivity is rather a function of the magnitude of the electromagnetic field intensity distribution. Also, the presence of a high refractive index substrate drastically affects the optical properties and subsequent sentivity of the dimer. In Chapter 5 the sensing properties of a cubic dimer is investigated as a function of orientation. As the separation distance of the nanocube dimer is decreased the orientation of the dimer drastically affects its coupling behavior. The expected dipole-dipole exponential coupling behavior of the dimer is found to fail at a separation distance of 14 nm for the edge-to-edge arrangement. The failure of the dipole-dipole coupling mechanism results from an increased contribution from the higher order multipoles (eg. quadrupole-dipole). This behavior begins at a separation distance of 6 nm for the face-to-face dimer. As a result, the relative ratio of the multipole to the dipole moment generated by the edge-to-edge dimer must be larger than the ratio for the face-to-face orientation.
In the last section of this thesis the catalytic properties of cubic nanoparticles composed of a platinum-silver alloy are investigated. The catalytic activity and selectivity towards a given reaction is intimately related to the physical and electronic structure of the catalyst. These cubic platinum-silver alloys are utilized as catalysts for the oxygen reduction reaction (ORR). A maximum enhancement in the specific activity (3.5 times greater than pure platinum) towards the ORR is observed for the cubic platinum-silver alloy with the lowest platinum content. This activity is investigated as a function of the physical structure of a cubic shaped catalyst as well as the electronic modifications induced by the formation of a platinum-silver alloy.
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Nelson, Darby. "Nonlinear Processes in Plasmonic Catalysis." The Ohio State University, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=osu1560853180547478.
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Ruffato, Gianluca. "Plasmonic Gratings for Sensing Devices." Doctoral thesis, Università degli studi di Padova, 2012. http://hdl.handle.net/11577/3422071.
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In last decades surface plasmon resonance has known an increasing interest in the realization of miniaturized devices for label-free sensing applications. The research in the direction of such plasmonic sensors with innovative performance in sensitivity and resolution opened to a wide range of unexpected physical phenomena. This work is aimed at understanding and modeling the physical principles of plasmonic platforms which support the exploitation of propagating plasmon modes for sensing purposes. Surface plasmon polaritons excitation and propagation on metallic gratings have been deeply studied and fully analyzed with theoretical models, numerical simulations and optical characterizations of fabricated samples. In particular the physics underlying azimuthal rotation of these nanostructures and the polarization role in this configuration have been theoretically and experimentally examined. The rotated configurations revealed considerable benefits in sensitivity and this improvement has been demonstrated by analyzing the optical response to surface functionalization and liquid solutions flowing through an embodied microfluidic cell. The exploitation of this plasmonic phenomenon in the conical mounting led to the design and realization of a promising setup for a new class of compact and innovative grating-based sensors. The different approaches, modeling – numerical – experimental, through which the problem has been examined, provided an exhaustive investigation into the physics of grating-coupled surface plasmon resonance and its innovative and original applications for advanced sensing devices.<br>Negli ultimi decenni la risonanza plasmonica di superficie ha conosciuto un crescente interesse nella realizzazione di dispositivi minaturizzati per applicazioni sensoristiche label-free. La ricerca nella direzione di sensori plasmonici con prestazioni innovative in sensibilita’ e risoluzione ha aperto ad un vasto panorama di inattesi fenomeni fisici. Questo lavoro di tesi ha l’obbiettivo di capire e analizzare i principi fisici su cui si basano i supporti plasmonici che sfruttano l’eccitazione di onde di superficie per fini sensoristici. L’eccitazione e la propagazione di plasmoni polaritoni di superficie su reticoli metallici sono state studiate e analizzate a fondo con modelli teorici, simulazioni numeriche e caratterizzazioni ottiche di campioni nanofabbricati. Nello specifico la fisica della rotazione azimutale di queste nanostrutture e il ruolo della polarizzazione in questa configurazione sono state esaminate con strumenti sia teorici che sperimentali. La rotazione del reticolo plasmonico ha rivelato considerevoli benefici in sensibilita’ e questo effetto e’ stato testato e dimostrato analizzando la risposta ottica a funzionalizzazioni di superficie e tramite l’analisi di soluzioni liquide flussate attraverso una cella microfluidica integrata. L’applicazione di questo fenomeno plasmonico ha portato all’individuazione di una configurazione promettente per una nuova classe di sensori a base plasmonica compatti e innovativi. I differenti approcci, modellistico –numerico – sperimentale, con cui il problema e’ stato affrontato, hanno fornito un’analisi completa della fisica della risonanza plasmonica di superficie con reticoli metallici e delle sue innovative applicazioni per dispositivi sensoristici avanzati.
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Reilly, Thomas H. III. "Plasmonic materials for optical sensing and spectroscopy." Diss., Connect to online resource, 2006. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3239396.
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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.<br>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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Fan, Yinan. "Rational synthesis of plasmonic/catalytic bimetallic nanocrystals for catalysis." Thesis, Sorbonne université, 2022. https://accesdistant.sorbonne-universite.fr/login?url=https://theses-intra.sorbonne-universite.fr/2022SORUS189.pdf.
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Parmi les différents nanocatalyseurs, ceux constitués de nanoparticules de métaux nobles méritent une attention particulière en raison de leurs propriétés électroniques, chimiques et même optiques (dans le cas de transformations renforcées par les plasmons). Le platine ou le palladium sont bien connus pour leurs remarquables propriétés catalytiques, mais ils sont chers et leurs ressources sont limitées. En outre, les nanocatalyseurs monométallique ne peuvent conduire qu'à une gamme limitée de réactions chimiques. Ainsi, notre stratégie a été de développer des nanocatalyseurs bimétalliques composés de deux éléments métalliques qui peuvent présenter des effets synergiques entre leurs propriétés physicochimiques et une activité catalytique accrue. Nous avons ainsi conçu des nanocatalyseurs bimétalliques de type cœur-coquille composés d'un cœur en argent et d'une coquille en platine. L'intérêt est de combiner les activités catalytiques élevées et efficaces de la coquille de platine avec le cœur d'argent hautement énergétique, capable de renforcer les activités de la coquille grâce à ses propriétés plasmoniques. En outre, ces nanoparticules bimétalliques présentent souvent une activité catalytique supérieure en raison de la modification de la distance inter-atomique Pt-Pt (c'est-à-dire l'effet de contrainte). Dans ce travail de thèse, les nanoparticules Ag@Pt ont été synthétisées via un processus en deux étapes utilisant d'une part des nanoparticules d'Ag synthétisées chimiquement comme germes et d'autre part des complexes platine-oleylamine qui sont ensuite réduits à la surface des germes à une température contrôlée. Différentes tailles de germes d'Ag de 8 à 14 nm avec une très faible distribution de taille (<10%) ont été obtenues en ajustant le temps de réaction, la rampe de température, la concentration en précurseur d'Ag et la température finale pendant la synthèse. Différentes épaisseurs de coquille (de 1 à 6 couches atomiques) ont été obtenues en ajustant le rapport entre les concentrations de précurseur de platine et de germe d'argent. L'activité catalytique des nanoparticules Ag@Pt a été testée en considérant une réaction modèle de réduction du 4-nitrophénol en 4-aminophénol par NaBH4 en phase aqueuse. Nous avons observé que l'épaisseur de la coquille de Pt et la taille du noyau d'Ag influençaient les propriétés catalytiques et conduisaient à une activité catalytique accrue par rapport à l'argent ou au platine pur. Ceci a été attribué à des effets synergiques. De plus, nous avons observé une augmentation de l'activité catalytique des nanoparticules Ag et Ag@Pt sous irradiation lumineuse. Ce phénomène a été corrélé à la génération d'électrons chauds dans les noyaux d'Ag. Afin de développer une plateforme de nanocatalyse supportée, nous avons fabriqué des auto-assemblages 3D appelés aussi supercristaux composés de nanoparticules d'Ag@Pt obtenus spontanément après dépôt sur un substrat solide en raison de leur distribution de taille étroite et de leur forme homogène. L'activité catalytique de ces supercristaux pour la réaction d'évolution de l’hydrogène (HER) a été étudiée en suivant in situ par microscopie optique la production de nanobulles de gaz H2. Trois comportements distincts dans l'activité photo-catalytique (activité, activité intermittente et non-activité) ont été observés sur les supercristaux dans la même région d'intérêt. En outre, 50 % des assemblages ont été déterminés comme étant actifs pour l'HER qui a été démontrée comme étant accompagnée par une corrosion oxydative de l’argent<br>Among several nanocatalysts, those based on noble metal NPs deserve particular attention because of their electronic, chemical and even optical properties (in the case of plasmonic-enhanced transformations). Platinum or palladium are well known for their remarkable catalytic properties, but they are expensive and their resources are limited. In addition, single component nanocatalysts can only lead to a limited range of chemical reactions. Thus, our strategy was to develop bimetallic nanocatalysts composed of two metal elements that can exhibit synergistic effects between their physicochemical properties and enhanced catalytic activity. We have thus designed bimetallic nanocatalysts of the core-shell type composed of a silver core and a platinum shell. The interest is to combine the high and efficient catalytic activities of the platinum shell surface with the highly energetic silver core capable of enhancing the activities of the shell through its plasmonic properties. In addition, these bimetallic NPs often exhibit superior catalytic activity due to the modification of the Pt-Pt atomic bonding distance (i.e. the strain effect). In this thesis work, Ag@Pt NPs have been synthesized via a two-step process using chemically synthesized spherical Ag NPs as seeds on the one hand and platinum complexes with oleylamine on the other hand which are then reduced on the surface of the seeds at a controlled temperature. Different Ag seed sizes from 8 to 14 nm with a very low size distribution (<10%) have been obtained by adjusting the reaction time, temperature ramp, Ag precursor concentration and final temperature during the synthesis. The control of the shell thicknesses (from 1 to 6 atomic layers) has been possible by adjusting the ratio of platinum precursor to silver seed concentrations. The catalytic activity of the core-shell Ag@Pt NPs was tested by a model reaction of reduction of 4-nitrophenol to 4-aminophenol by NaBH4 in aqueous phase. We have observed that the thickness of the Pt shell and the size of the Ag core influence the catalytic properties and led increased catalytic activity compared to pure silver or platinum. This was attributed to synergistic effects. Furthermore, we have observed an enhancement of the catalytic activity of Ag and Ag@Pt NPs under light irradiation. This is correlated to the generation of hot electrons in the Ag core. Finally, in order to develop a supported nanocatalysis platform, 3D self-assemblies also called supercrystals composed of Ag@Pt nanoparticles have been spontaneously obtained after deposition on a solid substrate due to their narrow size distribution and homogeneous shape. The catalytic activity of these supercrystals for the hydrogen evolution reaction (HER) has been studied by following in situ by optical microscopy the production of H2 gas nanobubbles. Three distinct behaviors in photo-catalytic activity (activity, intermittent activity and non-activity) have been observed on the supercrystals in the same region of interest. In addition, 50% of the assemblies were determined to be active for HER which was shown to be accompanied by oxidative corrosion of silver
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Sun, Xu. "Hybrid Plasmonic Devices for Optical Communication and Sensing." Doctoral thesis, KTH, Optik och Fotonik, OFO, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-205974.
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Hybrid plasmonic (HP) waveguides, a multi-layer waveguide structure supporting a hybrid mode of surface plasmonics and Si photonics, is a compromise way to integrate plasmonic materials into Si or SOI platforms, which can guide optical waves of sub-wavelength size, and with relative low propagation loss. In this thesis, several HP waveguides and devices are developed for the purposes of optical communications and sensing. The single-slot HP ring resonator sensor with 2.6µm radius can give a quality factor (Q factor) of 1300 at the communication wavelength of 1.5µm with a device sensitivity of 102nm/RIU (refractive index unit). The Mach-Zehnder interferometer (MZI) with a 40µm double-slot HP waveguide has a device sensitivity around 474nm/RIU. The partly open silicon side-coupled double-slot HP ring resonator has a device sensitivity of 687.5nm/RIU, with a Q factor over 1000 after optimization. Further, an all-optical switching HP donut resonator with a photothermal plasmonic absorber is developed, utilizing the thermal expansion effect of silicon to shift the resonant peak of the HP resonator. The active area has a radius of 10µm to match the core size of a single-mode fiber. By applying 10mW power of the driving laser to the absorber, the resonator transmitted power can be changed by 15dB, with an average response time of 16µs. Using the same fabrication flow, and removing the oxide materials using hydrogen fluoride wet etching, a hollow HP waveguide is fabricated for liquid sensing applications. The experimentally demonstrated waveguide sensitivity is about 0.68, which is more than twice that of pure Si waveguide device. Microelectromechanical systems (MEMS) can also be integrated into vertical HP waveguides. By tuning the thickness of the air gap, over 20dB transmitted power change was experimentally demonstrated. This can be used for optical switching applications by either changing the absorption or phase of the HP devices.<br><p>QC 20170427</p>
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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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Neri, Simona. "Tunable nanosystems for sensing and catalysis." Doctoral thesis, Università degli studi di Padova, 2016. http://hdl.handle.net/11577/3424423.
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Au NP have emerged as versatile scaffolds for applications in sensing and catalysis due to their unique features such as high stability, biocompatibility, ease of preparation, size- and shape-dependent optical and electronic properties and high surface area to volume ratio. The surface of Au NP can be readily modified with ligands containing functional groups such as thiols, phosphines and amines, which exhibit strong affinity for gold surfaces. The cooperative and collective effects achieved by the organization of organic components on the particle provide all the characteristics of a multivalent surface. Multivalent interactions on the monolayer surface can, hence, be applied to strengthen an interaction between the surface and small molecules. In particular, the self-assembly of small molecules on the multivalent surface of Au NP permits the realization of dynamic complex chemical systems that can be applied in the fields of catalysis, sensing and for the creation of tunable materials.
In the first part of this Thesis, the catalytic abilities of mixed monolayer gold nanoparticles composed of 8-trimethylammonium-octanethiol and different length thiols bearing the 4'-methyl-2,2'-bipyridine•Cu2+ complex has been studied. In particular, the influence of the geometry of the mixed monolayer gold nanoparticles on the efficiency and selectivity of the Diels-Alder reaction between cinnamoyl-1-methyl-1H-imidazole and cyclopentadiene has been studied. At the same time, the effect of the chiral environment obtained through the self-assembly of chiral peptide (Ac-(LLLL)-Leu-Leu-Gly-Trp-Ser(PO3H2)) on the enantioselection was evaluated. The results indicated in one case the formation of additional products. This can be justified considering the steric interactions between the alkyl chains and the catalysts when the catalytic headgroup is level with the monolayer surface. Furthermore, it was demonstrated that the self-assembly of a chiral enviroment on the surface of the Au NP can induce enantioselectivity, although only modestly.
In the second part of the thesis, a modular indicator-displacement-assay is presented. Small molecules with biological relevance are selectively recognized under competitive conditions by using Au NP functionalized with thiols terminating with 1,4,7-triazacyclononane (TACN)•Zn2+. The assay relies on the change in affinity of macrocyclic receptors, such as cavitands, cyclodextrins or calixarenes, for monolayer protected gold nanoparticles upon complexation of the respective target analyte. This change affects the equilibrium between the nanoparticles and a fluorescent reporter molecule leading towards a change in intensity of the fluorescent output signal. The recognition modules can be changed in order to tune the selectivity of the assay without affecting the nature of the output signal. The combined use of recognition modules results in an assay able to detect multiple analytes simultaneously and with high selectivity. A study of the orthogonality of the different receptor-analyte couples led to the demonstration of the possible exploitation of these kinds of arrays within the context of molecular computing.
In the third part, the possibility to self-assemble the molecular switch 4-(phenylazo)benzoic acid on the surface of Au NP functionalized with thiols terminating with 1,4,7-triazacyclononane (TACN)•Zn2+ was studied in order to reversibly modulate by light, the affinity of small molecules for the surface. The displacement studies of both probes 343Coumarin-GDDD and 6,8-dihydroxy-1,3-pyrenedisulfonic acid by cis/trans 4-(phenylazo)benzoic acid revealed that the two isomers have different affinities for the surface.This key point was then exploited to use light for the reversible up- and downregulation of the catalytic activity of the nanoparticle under investigation.<br>L’ importanza delle Au NP come supporto versatile per applicazioni nell’ambito della catalisi e dei sensori nasce dalle loro esclusive caratteristiche come, ad esempio, alta stabilità, biocompatibilità, facilità di preparazione, specifiche proprietà ottiche and elettroniche dipendenti dalla forma e dalle dimensioni e dal loro alto rapporto area/volume. Inoltre, la superficie delle Au NP può essere facilmente funzionalizzata mediante leganti contenenti vari gruppi funzionali, come tioli, fosfine e ammine che presentano alta affinità per la superficie d’oro.
Gli effetti collettivi e cooperativi ottenuti grazie all’organizzazione di componenti organici sulla particella, fornisce multivalenza alla superficie. Le interazioni multivalenti sul monostrato possono, quindi, essere applicate per rafforzare un’interazione tra la superficie funzionalizzata e piccole molecole. In particolare l’auto assemblaggio di piccole molecole su una superficie multivalente permette la realizzazione di sistemi chimici dinamici che possono essere applicati nel campo della catalisi, dei sensori e per la creazione di sistemi regolabili.
Nella prima parte della Tesi, viene studiata la capacità catalitica di nanoparticelle composte da un monostrato misto (in particolare composte da 8-trimetilammonio-octiltiolo e tioli di diversa lunghezza contenenti il complesso metallico 4’-metil-2,2’-bipiridina•Cu2+ . In particolare viene studiata l’influenza della geometria indotta dal monostrato misto sulla efficienza e selettività della reazione di Diels-Alder tra cinnamoil-1-metil-1H- imidazolo e il ciclopentadiene.
Allo stesso tempo, viene studiato l’effetto dell’ambiente chirale ottenuto grazie all’autoassemblaggio di un peptide chirale (Ac-(LLLL)-Leu-Leu-Gly-Trp-Ser(PO3H2)) sulla enantioselettività della reazione.
I risultati dimostrano che in alcuni casi la geometria può influenzare la formazione di prodotti addizionali. Questo può essere giustificato come il risultato di interazioni steriche tra catene alchiliche e catalizzatore, quando quest’ultimo si trova alla pari della superficie del monostrato. Inoltre, è stato dimostrato che, assemblando un peptide chirale sulla superficie delle Au NP, è possibile indurre enantioselettività, sebbene limitata.
Nella seconda parte della Tesi viene presentato un saggio modulare basato sullo spiazzamento di un indicatore. Piccole molecole con rilevanza biologica sono selettivamente riconosciute utilizzando Au NP funzionalizzate con tioli che presentano come gruppo terminale il 1,4,7-triazaciclononano (TACN)•Zn2+. Il saggio si basa sul cambio di affinità di recettori macrociclici come, ad esempio cavitandi, ciclodestrine o calixareni, per le nanoparticelle, dopo avere formato il complesso con la loro rispettiva molecola bersaglio. Questo cambio influenza l’equilibrio tra nanoparticelle e una sonda fluorescente e provoca, di conseguenza, un cambio nel segnale di fluorescenza. I moduli di riconoscimento possono essere cambiati in modo da poter controllare la selettività del saggio senza influenzare la natura del segnale in uscita. L’ utilizzo contemporaneo di tre moduli permette di creare un sistema capace di rivelare più analiti simultaneamente e con alta selettività. Lo studio dell’ortogonalità delle differenti coppie recettore/analita permette di dimostrare la possibilità di utilizzo di questo tipo di sistemi nel campo dei computer molecolari.
Nella terza parte viene studiata la possibilità di auto assemblare l’interruttore molecolare acido 4-(fenilazo)benzoico sulla superficie di Au NP funzionalizzate con tioli che presentano come gruppo terminale il
1,4,7-triazaciclononano (TACN)•Zn2+, con lo scopo di modulare con la luce (in modo reversibile) l’affinità di piccole molecole per la superficie. Gli studi di spiazzamento di entrambi i probe cumarina343-GDDD e l’acido 6,8-diidrossi-1,3-pirenedisulfonico promosso dal cis/trans acido 4-(fenilazo)benzoico rivelano che i due isomeri hanno diverse affinità per la superficie delle nanoparticelle. Questo punto chiave viene sfruttato per permettere la regolazione tramite luce dell’attività delle nanoparticelle in esame.
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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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Stein, Benedikt. "Plasmonic devices for surface optics and refractive index sensing." Phd thesis, Université de Strasbourg, 2012. http://tel.archives-ouvertes.fr/tel-00849967.
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In this thesis devices for controlling the flow of surface plasmon polaritons are described. Dielectric and metallic nanostructures were designed for this purpose, and characterized by leakage radiation microscopy in real and in reciprocal spaces. Manipulation of surface plasmons by dielectric lenses and gradient index elements is presented, and negative refraction, steering and self-collimation of surface plasmons in one- and two-dimensional plasmonic crystals is demonstrated. The achieved degree of control was applied for routing of nanoparticles by optical forces, as well as for two methods of enhancing the figures of merit of plasmonic refractive index sensors, based on the one hand on Fano resonances natural to leakage radiation microscopy, and on the other hand on anisotropie plasmonic bandstructures.
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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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Li, Zhibo. "Plasmonic nano apertures for molecular sensing and colour displays." Thesis, University of Glasgow, 2015. http://theses.gla.ac.uk/6986/.
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The discovery of extraordinary optical transmissions through metallic periodical subwavelength apertures has seen promising applications in filtering and sensing. Such a unique optical property is due to the excitation of surface plasmon resonance. Through accurate control of the aperture’s geometrical shape and dimension, the optical resonance of such nanostructure can be tuned in a wide range from the visible to near infrared. In addition, the highly confined resonant electromagnetic field supported by such a nanostructure can be utilised in surface enhanced Raman spectroscopy. This thesis studied metallic nano aperture arrays for the application of molecular sensing and colour displays. The development of nanofabrication processes for making complex metallic nano apertures was the foundation of this research. Gold was chosen as the appropriate material for sensing mainly due to its stable chemical and physical properties. Aluminium was selected for making colour pixels because its optical resonant frequency can be tuned over the whole visible range. One aspect of this research relating to surface enhanced Raman spectroscopy considered symmetrical gold nano apertures: annular aperture arrays and circular aperture arrays. Comparisons between two annular aperture arrays and between one annular aperture array and one circular aperture array were carried out. The asymmetrical gold nanostructures studied were split-ring shaped aperture arrays. One structure can be used to generate two polarisation dependent resonances in which one of them was able to match the laser in the Raman spectrometer for molecular interrogation and the other was not. The other aspect related to dual-colour pixels. Aluminium cross-shaped aperture arrays were fabricated. By varying the structural dimensions and incident polarisation, colours could be tuned over the whole visible range. Polarisation controlled chromatic displays were demonstrated by employing these pixels.
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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<br>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.<br>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.<br>2031-01-02
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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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Nicoli, Francesca. "PLASMONIC NANOPORES: exploring new possibilities in DNA sensing and trapping." Thesis, KTH, Skolan för informations- och kommunikationsteknik (ICT), 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-177891.
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In this work we explore the new DNA sensing and trapping possibilities offered by a plasmonic nanopore. This new device combines the sensing capability of solid state nanopores with the effects arising from the collective oscillation of electrons in gold nanoparticles (plasmons). The device consists in a nanopore drilled in a silicon nitride membrane and triangular gold nanoparticles in a bowtie configuration co-aligned with the pore. We exploit plasmonic heating to characterise the metallic nanostructures and we study its effect on pore stability. These observations allow us to optimise the sample characteristics and the experimental conditions for DNA translocation experiments. In this regard, we focus on how plasmonic excitation influences the depth of a current blockade, evaluating the contribution of the shift of the resonance spectrum due to the presence of a molecule in the surroundings of the particles. We also forwarded the hypothesis of a contribution of thermophoretic forces, due to high local heating induced by the plasmonic structures. Heating and thermophoretic forces could also influence the increase in translocation frequency, observed in our experiments upon plasmonic excitation. This increase is probably due to changes in the buffer viscosity which affects the magnitude of the pore’s capture radius of the DNA molecules. We also explore the possibility of controlling the motion of DNA inside the pore by means of optical trapping. This principle is based on utilising optical forces from the strong gradient of the evanescent electric field that is created, upon illumination, from the surface of the metallic nanoparticles to few nanometers away. From preliminary molecular dynamics simulations, we expect the optical force to be able to overcome the driving electric force at experimentally relevant excitation powers. Indeed, for plasmonic excitation around laser power 10 mW and above, we observed long (> 1s) and multilevel events, which indicate successful plasmonic trapping of DNA in nanopore. However we note that such long events were often present also after turning off the plasmonic excitation, likely due to permanent sticking of to the pore/bowtie. Although we need to solve some issues of sticking of molecules and to perform more systematic experiments before drawing any conclusion regarding trapping, the results are promising and indicate that plasmonic nanopores may enable light-controlled trapping of DNA in nanopores.
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Rew, Kirsty G. "Plasmonic filters for ambient and near infrared sensing on CMOS." Thesis, University of Glasgow, 2017. http://theses.gla.ac.uk/8570/.
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The light sensors market is growing, driven largely by increased use of proximity detection and ambient light sensing (ALS) in consumer electronics. There is high demand for reduced cost and physical size of light sensors, however the spectral filter technology used on complementary metal-oxide semiconductor (CMOS) chips has not advanced significantly. Plasmonic filters have been proposed as a superior alternative offering reduced cost and thickness, among other advantages. In this work plasmonic filters are investigated in the near infrared (NIR) range for proximity sensing applications, and the visible range for ALS applications using CMOS compatible materials and fabrication processes. The plasmonic filters are thin metallic films nanostructured with an array of subwavelength holes that facilitate coupling with surface plasmon polaritons (SPP) and localised surface plasmons (LSP). They exhibit extraordinary optical transmission with peak transmission wavelengths controlled by the geometry and size of the hole array. Filters were designed on glass substrate by electromagnetic simulations using a finite-difference time-domain (FDTD) method, created using micro and nano-fabrication techniques, and then measured by microspectrophotometry to evaluate their spectral response. Following characterisation, the NIR filter was fabricated directly onto a CMOS chip and the spectral response was assessed by chip measurement for a proof-of-concept demonstration of an integrated device. The NIR plasmonic filter exhibited poor suitability on CMOS due to high order plasmonic resonances in the visible range that were enhanced by Fabry-Pérot resonances supported by the CMOS stack. The most common plasmonic filter, a circular-shaped hole nanostructure, is sensitive to angle of incidence (AOI) making it unsuitable for ALS applications. Preliminary designs for plasmonic ALS filters with low sensitivity to AOI were demonstrated, by characterisation on glass, using a cross-shaped hole nanostructure. Design dimensions that produced this quality were decreased array period and decreased ratio of the cross arm-length to arm-width, due to increased separation between the SPP and LSP resonances generated by the plasmonic hole array filter.
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Gilroy, Kyle Daniel. "Shape-Engineering Substrate-Based Plasmonic Nanomaterials." Diss., Temple University Libraries, 2015. http://cdm16002.contentdm.oclc.org/cdm/ref/collection/p245801coll10/id/337002.
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Mechanical Engineering<br>Ph.D.<br>The advancement of next generation technologies is reliant on our ability to engineer matter at the nanoscale. Since the morphological features of nanomaterials dictate their chemical and physical properties, a significant effort has been put forth to develop syntheses aimed at fine tuning their size, shape and composition. This massive effort has resulted in a maturing colloidal chemistry containing an extensive collection of morphologies with compositions nearly spanning the entire transition of the periodic table. While colloidal nanoparticles have opened the door to promising applications in fields such as cancer theranostics, drug delivery, catalysis and sensing; the synthetic protocols for the placement of nanomaterials on surfaces, a requisite for chip-based devices, are ill-developed. This dissertation serves to address this limitation by highlighting a series of syntheses related to the design of substrate-based nanoparticles whose size, shape and composition are controllably engineered to a desired endpoint. The experimental methods are based on a template-mediated approach which sees chemical modifications made to prepositioned thermally assembled metal nanostructures which are well bonded to a sapphire substrate. The first series of investigations will highlight synthetic routes utilizing galvanic replacement reactions, where the prepositioned templates are chemically transformed into hollow nanoshells. Detailed studies are provided highlighting discoveries related to (i) hollowing, (ii) defect transfer, (iii) strain induction, (iv) interdiffusion, (v) crystal structure and (vi) the localized surface plasmon resonance (LSPR). The second series of investigations, based on heterogeneous nucleation, have Au templates serve as nucleation sites for metal atoms arriving in either the solution- or vapor phase. The solution-phase heterogeneous nucleation of Ag on Au reveals that chemical kinetics (injection rate & precursor concentration) can be used to control the nature of how Ag atoms grow on the Au template. It was discovered that (i) slow kinetics leads to an anisotropic growth mode (heterodimeric structures), (ii) fast kinetics causes a very uniform deposition (Au-Ag coreshell morphology, or Au@Ag) and (iii) medium kinetics produces structures with an intermediate morphology (truncated octahedron). In the second case, where the nucleation event is carried out at high temperatures, the Ag vapor is sourced from a sublimating foil onto adjacent Au templates. This process drives the composition and morphology from a Au Wulff-shape to a homogeneous Au-Ag nanoprism. By tracking over time the (i) morphological features, (ii) LSPR and (iii) composition; insights into the fundamental atomic scale growth mechanisms are elucidated. Overall, substrate-based template-mediated syntheses have proven to be an effective route for directing growth pathways toward a desired endpoint giving rise to an impressive new group of complex substrate-based nanostructures with asymmetric, core-shell and hollowed morphologies. While this dissertation is focused heavily on the development of synthetic procedures aimed at generating substrate-based plasmonic nanomaterials, the last chapter will serve to highlight a series of on-going studies aimed at defining these nanomaterials as highly effective heterogeneous catalysts. Several examples are shown including (i) nanoparticle films synthesize via sputter deposition, (ii) mechanically induced nanotexturing of bulk copper foils, (iii) ultra-small AuPd nanoparticles synthesized via pulse laser, (iv) substrate-based AuCu nanoprisms and (v) the Wulff in a Cage Morphology.<br>Temple University--Theses
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Mesch, Martin [Verfasser], and Harald [Akademischer Betreuer] Giessen. "Linear & nonlinear plasmonic sensing : complex coupled plasmonic structures, functionalization, and nonlinear effects / Martin Mesch ; Betreuer: Harald Giessen." Stuttgart : Universitätsbibliothek der Universität Stuttgart, 2016. http://d-nb.info/1118371402/34.
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Seo, Sungkyu. "Nano scale devices for plasmonic nanolithography and rapid sensing of bacteria." Texas A&M University, 2007. http://hdl.handle.net/1969.1/85832.
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This dissertation contains two different research topics. One is a "Nano Scale Device
for Plasmonic Nanolithography - Optical Antenna' and the other is a 'Nano Scale Device for
Rapid Sensing of Bacteria - SEPTIC'. Since these two different research topics have little
analogy to each other, they were divided into different chapters throughout the whole
dissertation. The 'Optical Antenna' and 'Nanowell / Microwell / ISFET Sensor' represent the
device names of each topic 'Plasmonic Nanolithography' and 'Rapid Sensing of Bacteria'
respectively.
For plasmonic nanolithography, we demonstrated a novel photonic device - Optical
Antenna (OA) - that works as a nano scale object lens. It consists of a number of sub-wavelength
features in a metal film coated on a quartz substrate. The device focuses the incident light to
form a narrow beam in the near-field and even far-field region. The narrow beam lasts for up to
several wavelengths before it diverges. We demonstrated that the OA was able to focus a subwavelength
spot with a working distance (also the focal length) of several µm, theoretically and
experimentally. The highest imaging resolution (90-nm spots) is more than a 100% improvement
of the diffraction limit (FWHM = 210 nm) in conventional optics. A model and 3D
electromagnetic simulation results were also studied. Given its small footprint and subwavelength
resolution, the PL holds great promise in direct-writing and scanning microscopy. Collaborative work demonstrated a Nanowell (or Microwell) device which enables a
rapid and specific detection of bacteria using nano (or micro) scale probe to monitor the electric
field fluctuations caused by ion leakage from the bacteria. When a bacteriophage infects a
bacterium and injects its DNA into the host cell, a massive and transitory ion efflux from the
host cell occurs. SEPTIC (SEnsing of Phage-Triggered Ion Cascade) technology developed by
collaboration uses a nanowell device to detect the nano-scale electric field fluctuations caused by
this ion efflux. The SEPTIC provides fast (within several minutes), effective (living cell only),
phage specific (simple and less malfunction), cheap, compact and robust method for bacteria
sensing. We fabricated a number of devices, including 'Nanowell', 'Microwell' and 'ISFET
(Ion Selective Field Effect Transistor)', which detect bacteria-phage reactions in frequency
domain and time domain. In the frequency domain, detected noise spectrum is characterized by
1/f[beta]. The positive reaction showed much higher [beta] =̃1 than that of background noise or
negative reaction ( [beta] =̃0). For the time domain, we observed abnormal pulses (> 8[omega] ) lasting
0.1 ~ 0.3 s which match the duration of ion flux reported by prior literatures. And the ISFET
showed the phage-infection-triggered pulse in the form of the deviated drain current. Given the
size of nanowell (or microwell, ISFET) and the simplified detection electronics, the cost of
bacteria sensing is significantly reduced and the robustness is well improved, indicating very
promising applications in clinical diagnosis and bio-defense.
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Malone, Marvin Jr. "Plasmonic Sensing And Spectroscopy of Subwavelength Particles with an Infrared Microscope." The Ohio State University, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=osu1354561034.
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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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Cary, ReJeana. "Sensing of Small Molecules, Biomarkers, and Pathogens using Unique Plasmonic Assay Platforms." University of Cincinnati / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1595848703283784.
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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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<p>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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Papa, Letizia. "Synthesis of hybrid nanosheets of graphene oxide, titania and gold and palladium nanoparticles for catalytic applications." Universidade de São Paulo, 2017. http://www.teses.usp.br/teses/disponiveis/46/46136/tde-19062017-083751/.
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Nanocatalysis has emerged in the last decades as an interface between homogeneous and heterogeneous catalysis, offering simple solutions to problems that conventional materials have not been able to solve. In fact, nanocatalyst design permits to obtain structures with high superficial area, reactivity and stability, and at the same time presenting good selectivity and facility of separation from reaction mixtures. In this work, we prepared hybrid structures comprising gold, palladium and silver nanoparticles (Au, Pd and Ag NPs), titanate nanosheets (TixO2), graphene oxide (GO), and partially reduced graphene oxide (prGO). We focused on bi- and tri-components hybrids, namely TixO2, M/(pr)GO and M/TixO2/(pr)GO (M = Au, Pd or Ag) and developed facile, versatile and environment-friendly preparation methods with an emphasis on control over physicochemical features such as size, shape and composition. In order to exploit the catalytic applications, we employed the reduction of 4-nitrophenol as a model reaction, followed by visible-light assisted oxidation of p-aminothiophenol (PATP). With these tests, we unraveled metal-support interactions and cooperative effects that render hybrid structures superior to their individual counterparts.<br>A nanocatálise surgiu nas últimas décadas como uma interface entre catálise homogênea e heterogênea, oferecendo soluções simples a problemas que os materiais convencionais não conseguiram resolver. De fato, o design de nanocatalisadores permite obter estruturas com grande área superficial, reatividade e estabilidade, e ao mesmo tempo apresentando boa seletividade e facilidade de separação de misturas reacionais. Neste trabalho apresentamos a preparação de estruturas híbridas compostas por nanopartículas de ouro, paládio e prata (Au, Pd e Ag NPs), nanofolhas de titanato (TixO2), óxido de grafeno (GO) e óxido de grafeno parcialmente reduzido (prGO). Focamos em híbridos do tipo M/TixO2, M/(pr)GO e M/TixO2/(pr)GO (M = Au, Pd ou Ag) e desenvolvemos métodos de preparação simples, versáteis e ambientalmente amigáveis, com ênfase no controle sobre tamanho, forma e composição. Para explorar as potencialidades catalíticas utilizamos a redução do 4-nitrofenol como reação modelo, e em seguida a oxidação assistida por luz do p-aminotiofenol (PATP). Com esses testes, investigamos interações metal-suporte e efeitos cooperativos que tornam as estruturas hibridas superiores a cada um dos materiais que as compõem.
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Chamanzar, Maysamreza. "Hybrid nanoplasmonic-nanophotonic devices for on-chip biochemical sensing and spectroscopy." Diss., Georgia Institute of Technology, 2012. http://hdl.handle.net/1853/50145.
Full textAbstract:
Hybrid plasmonic-photonic structures were introduced as novel platforms for on-chip biochemical sensing and spectroscopy. By appropriate coupling of photonic and plasmonic modes, a hybrid architecture was realized that can benefit from the advantages of integrated photonics such as the low propagation loss, ultra-high Q modes, and robustness, as well as the advantages of nanoplasmonics such as extreme light localization, large sensitivities, and ultra-high field enhancements to bring about unique performance advantages for efficient on-chip sensing. These structures are highly sensitive and can effectively interact with the target biological and chemical molecules. It was shown that interrogation of single plasmonic nanoparticles is possible using a hybrid waveguide and microresonator-based structure, in which light is efficiently coupled from photonic structures to the integrated plasmonic structures. The design, implementation, and experimental demonstration of hybrid plasmonic-photonic structures for lab-on-chip biochemical sensing applications were discussed. The design goal was to achieve novel, robust, highly efficient, and high-throughput devices for on-chip sensing. The sensing scenarios of interest were label-free refractive index sensing and SERS. Nanofabrication processes were developed to realize the hybrid plasmonic-photonic structures. Silicon nitride was used as the material platform to realize the integrated photonic structure, and gold was used to realize plasmonic nanostructures. Special optical characterization setups were designed and implemented to test the performance of these nanoplasmonic and nanophotonic structures. The integration of the hybrid plasmonic-photonic structures with microfluidics was also optimized and demonstrated. The hybrid plasmonic-photonic-fluidic structures were used to detect different analytes at different concentrations. A complete course of research from design, fabrication, and characterization to demonstration of sensing applications was conducted to realize nanoplasmonic and integrated photonic structures. The novel structures developed in this research can open up new potentials for biochemical sensors with advanced on-chip functionalities and enhanced performances.
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Tittl, Andreas [Verfasser], and Harald [Akademischer Betreuer] Giessen. "Hybrid plasmonic devices for sensing and thermal imaging / Andreas Tittl. Betreuer: Harald Giessen." Stuttgart : Universitätsbibliothek der Universität Stuttgart, 2015. http://d-nb.info/1075494044/34.
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Idehenre, Ighodalo U. "Evanescent and Plasmonic Sensing Using Linear and Radial Polarization Modes in Tapered Microfibers." University of Dayton / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1367346795.
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Adnan, Rohul. "Gold-based Nanomaterials: Spectroscopy, Microscopy and Applications in Catalysis and Sensing." Thesis, University of Canterbury. Chemistry, 2015. http://hdl.handle.net/10092/10507.
Full textAbstract:
The birth of nanotechnology era has revolutionized materials science, catalysis and field of optoelectronics. Novel and unique phenomena emerge when material dimensions are reduced to ultra-small size regime and enter nanometre (2-100 nm) realm. Such novel materials are expected to replace bulk materials, offering lower cost of manufacturing and enabling progress in many areas such as solar cell, drug delivery, quantum communication and computing, catalysis and sensing applications. With the progress in nanomaterial synthesis and fabrication, the need for the state-of-art characterization techniques became obvious; such techniques help to establish a complete understanding of the nature and interactions of nanosized materials.
In this thesis, the first part focuses on the synthesis of gold and ruthenium clusters, namely Au8, Au9, Au101, Ru3, Ru4 and AuRu3, using the well-established synthetic protocols in the literature. Apart from the standard lab-based characterization techniques such as nuclear magnetic resonance (NMR), UV-visible spectroscopy (UV-vis) and Fourier Transform Infra-red (FTIR), a less explored but useful technique far infra-red (far IR) spectroscopy, available at the Australian Synchrotron (AS), was employed to investigate the vibrational modes in these clusters. Peaks in the experimental far IR spectra were assigned unambiguously to specific vibrations by comparing with the ones generated via DFT calculations with the help of collaborators, group of Professor Gregory Metha, University of Adelaide. For the Au9 cluster, three significant gold core vibrations are observed at 157, 177 and 197 cm-1 in the experimental spectrum. In the case of the Ru3 cluster, only a single ruthenium core vibration is identified within the spectrum, at 150 cm-1 with the calculated force constant, k = 0.33 mdyne/Å. The Ru4 cluster exhibits two metal core vibrations at 153 and 170 cm-1 with force constants of 0.35 and 0.53 mdyne/Å, respectively. Substitution with a gold atom yielding a mixed metal AuRu3 cluster shifts the core transitions toward higher wavenumbers at 177 and 299 cm-1 with an increase in force constants to 0.37 and 1.65 mdyne/Å, respectively. This is attributed to the change in chemical composition and geometry of the metal cluster core. A combination of the DFT calculations and high quality synchrotron-based experimental measurements allowed the full assignment of the key transitions in these clusters.
Next, these clusters were fabricated into heterogeneous catalysts by depositing on different metal oxide nanopowders. Synchrotron X-ray photoelectron spectroscopy (XPS) and X-ray absorption spectroscopy (XAS) studies were performed at the Australian Synchrotron and the Photon Factory synchrotron in Japan to investigate the electronic structure of Au8, Au9 and Au101 on TiO2 catalysts. The XPS analysis reveals that “as-deposited” Au8 and Au9 retain some un-aggregated clusters while Au101 show bulk-like gold. These findings are in line with TEM observations, where the aggregates (large particles, > 2 nm) of Au8, Au9 and Au101 are hardly seen under HRTEM. UV-visible diffuse reflectance spectroscopy (UV-vis DRS) studies show the absence of localised surface plasmon resonance (LSPR) peaks in these “as-deposited” clusters, suggesting they are below 2 nm in size. Importantly, the XAS spectrum of “as-deposited” Au9 clusters estimates that 60% of pure, un-aggregated Au9 clusters and 40% of bulk gold in the sample. Upon calcination under O2 and combined O2 and H2 (O2-H2), Au8, Au9 and Au101 clusters form larger nanoparticles (> 2 nm) with the appearance of LSPE peak in UV-vis DR spectra. In addition, majority of the phosphine ligands (that stabilise the gold core) dislodge and form phosphine oxide-like species by interacting with oxygen on the TiO2 surface.
The third part focused on testing the catalytic performance of the supported Au8, Au9, Au101, Ru3, Ru4 and AuRu3 clusters on different TiO2, SiO2, ZnO and ZrO2 in benzyl alcohol oxidation. Au101-based catalysts display the highest catalytic activity with a turn-over frequency (TOF) up to 0.69 s-1. The high catalytic activity is attributed to the formation of large Au nanoparticles (> 2 nm) that coincides with the partial removal of capping ligands. Au8 and Au9 clusters which contain NO3- counter anions are found to be inactive in benzyl alcohol oxidation. Further work shows that the presence of NO3- species diminishes the catalytic activity. Monometallic ruthenium clusters, Ru3 and Ru4, are found to be inactive yet the bimetallic AuRu3 clusters are active in benzyl alcohol oxidation, suggesting the synergistic effect between ruthenium and gold metal. Investigation of catalytic testing parameters reveals that tuning selectivity of the product is possible through manipulating the reaction temperature.
Finally, a joint experiment with Prof. Wojtek Wlodarski’s group at RMIT, Melbourne was undertaken to test the sensing ability of Au9 clusters for hydrogen detection. Au9 clusters were deposited onto radio-frequency (RF) sputtered WO3 films at two different concentrations; 0.01(S1) and 0.1(S2) mg/mL. It was found that the optimal temperatures for sensor S1 and S2 were 300 °C and 350 °C, respectively. The sensor with lower Au9 concentration (S1) displays a faster response and recovery time, and a higher sensitivity toward H2. HRTEM studies reveal that the sensor S1 contain a significant population of sub-5 nm Au nanoparticles which might be responsible for a faster rate of H2 adsorption and dissociation. The key finding in this study suggest that the addition of catalytic layer such as ultra-small Au9 clusters results in improved sensitivity and dynamic performance (response and recovery time) of H2 sensors.
In summary, this thesis demonstrated that cluster-based nanomaterials have wide range of applications spanning from catalysis to sensing. Further improvements in material synthesis and use of multiple complimentary characterization techniques allowed better understanding of the nature of the key active species (metal nanoparticles) assisting design of catalysts and sensors with enhanced performance.
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Seidenkranz, Daniel. "Barbiturates and Modified Hamilton Receptors for Supramolecular Catalysis, Sensing, and Materials Applications." Thesis, University of Oregon, 2019. http://hdl.handle.net/1794/24194.
Full textAbstract:
Supramolecular chemistry (chemistry beyond the molecule) is the study and synthesis of complex molecular architectures from simple subunits using non-covalent interactions. The types of non-covalent interactions that are used for the self-assembly of these complex molecular architectures include electrostatic interactions (e.g. ionic, halogen, and hydrogen bonding), π-effects, van der Waals interactions, metal coordination, and hydrophobic effects. While these interactions are often used in concert, some of the most
successful and ubiquitous approaches for the design and construction of new host–guest architectures are the incorporation of hydrogen bonding motifs. A popular class of molecules capable of making strong, highly directional hydrogen bonds is barbiturates.
Barbiturates have a well-known reputation as potent hypnotics, anticonvulsants, and anxiolytics but recent years have seen a renewed interest in these molecules due to their unique, symmetric acceptor-donor-acceptor hydrogen bonding motif. In addition, receptors with complementary hydrogen bonding motifs capable of binding barbiturates have also been reported, namely those based on the work of Hamilton et al. Collectively, barbiturates and their receptors have seen widespread use in a variety of applications including sensing, optoelectronics, catalysis, and the design of soft materials.
The work presented in this dissertation describes the development of novel Hamilton receptors for supramolecular catalysis and barbiturate sensing, as well as the design of new synthetic barbiturates. Together this body of research aims to extend the utility of these types of host–guest systems as well as continue to develop and refine the
supramolecular design principles that govern the binding interactions between barbiturates and a variety of Hamilton-type receptors.
This dissertation includes both previously published/unpublished and co-authored material.
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Silva, Anderson Gabriel Marques da. "Interconnecting controlled synthesis, plasmonic, and catalysis: from education to the next generation of nanomaterials for triggering green transformations." Universidade de São Paulo, 2017. http://www.teses.usp.br/teses/disponiveis/46/46136/tde-19092017-102518/.
Full textAbstract:
This dissertation is directed towards the fundamental understanding of the controlled synthesis of noble-metal (silver, gold, and palladium) and metal oxide (manganese and copper oxide) nanostructures as well as their applications in heterogeneous and plasmonic catalysis. In the first part of this work (Section 1), we provided a general background concerning the science of controlled nanomaterials, their syntheses, properties, and applications in catalysis and plasmonic catalysis. Then, we describe and developed a series of protocols for the synthesis of these nanomaterials with controlled sizes and structures (spheres, cubes, rods, shells, flowers, dendrites, and tadpoles), mainly focusing on the mechanistic understanding of their formation and how physical and chemical parameters (size, shape, composition, surface morphology) may influence/modify their catalytic properties (Sections 2 and 3). In Section 4, we turned our attention for the design of simple protocols for the synthesis of advanced nanomaterials that are interesting for green catalytic transformations applications. In this case, we envisioned the use of MnO2-Au nanomaterials (nanowires and nanoflowers) displaying several properties (unique pore structure, high surface area, ultrasmall Au NPs at the surface, high concentration of oxygen vacancies and Auδ+ species, strong metal-support interactions, and uniform shapes and sizes) that are desirable for catalyzing a series of green oxidation reactions in mild conditions (low temperatures and molecular oxygen or atmospheric air as the oxidants). In Section 5, we have demonstrated that catalysis and optical properties can be merged together to improve catalytic processes, the so called-plasmonic catalysis. This allowed us the use of visible light as the energy input to drive chemical transformations in mild conditions and then provide new insights regarding the various factors that affect SPR-mediated catalytic activities in plasmonic nanostructures. Finally, in Section 6, we focused our attention on how important is to introduce both nanoscience and the synthesis/characterization of nanomaterials having controlled physicochemical features to undergraduate students. Specifically, we have described simple laboratory experiments for the synthesis of nanomaterials (gold nanospheres and Cu(OH)2/CuO nanowires) displaying uniform sizes and shapes in order to investigate and explain their optical properties, catalytic activities and formation mechanisms.<br>Não consta resumo na publicação.
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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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Rodríguez, Fortuño Francisco José. "Design and implementation of plasmonic metamaterials and devices." Doctoral thesis, Universitat Politècnica de València, 2013. http://hdl.handle.net/10251/31207.
Full textAbstract:
La plasmónica es la ciencia que estudia la interacción, a escala nanométrica, entre la luz y los electrones libres de los metales, dando lugar a la propagación de ondas altamente confinadas a su superficie. La plasmónica tiene multitud de aplicaciones en nanotecnología, como son el sensado biológico y químico, espectroscopía, nanolitografía, comunicaciones de banda ultra ancha integradas en chips, nanoantenas para luz, filtrado, y manipulación de señales ópticas, entre muchas otras. Una de las aplicaciones más novedosas es la creación de metamateriales: estructuras artificiales diseñadas para controlar la propagación de la luz, con aplicaciones fascinantes como la lente perfecta o la capa de invisibilidad. La plasmónica y los metamateriales están al frente de la investigación actual en fotónica, gracias al auge de la nanotecnología y la nanociencia, que abre las puertas a una gran cantidad de nuevas aplicaciones.
Esta tesis, desarrollada en el Centro de Tecnología Nanofotónica de Valencia de la UPV, en colaboración con la University of Pennsylvania y King's College London, trata de aportar nuevas ideas, estructuras y dispositivos a los campos de la plasmónica y los metamateriales, tratando de realizar su fabricación y medida experimental cuando sea posible. La tesis no se ciñe a una única aplicación o dispositivo, sino que realiza una extensiva exploración de los diversos sub-campos de la plasmónica en busca de fenómenos novedosos. Los resultados descritos son los siguientes:
En el campo de los metamateriales de índice negativo se presentan dos estructuras: nanocables en forma de U, y guías coaxiales plasmónicas. En el campo del sensado plasmónico se presenta el diseño y la prueba experimental de un sensor se sustancias químicas de altas prestaciones con nanocruces metálicas. También se detallan teóricamente: un novedoso dispositivo para luz lenta e inversión temporal de pulsos basada en metamateriales y cristales fotónicos, un metamaterial para conversión de polarización sintonizable mediante pérdidas, un análogo plasmónico al efecto de levitación Meissner en superconductores y un método de reducción de pérdidas en guías plasmónicas mediante interferencia en guías multimodo. Por último se presenta teórica y experimentalmente un nuevo ejemplo fundamental de interferencia de campo cercano, logrando la excitación unidireccional de modos fotónicos ---ya sean plasmónicos o no--- mediante los campos cercanos de un dipolo circularmente polarizado.<br>Rodríguez Fortuño, FJ. (2013). Design and implementation of plasmonic metamaterials and devices [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/31207<br>TESIS<br>Premiado
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Payne, Daniel Tony. "Synthesis of asymmetric DMAP derivatives and their applications in asymmetric catalysis and sensing." Thesis, University of Birmingham, 2017. http://etheses.bham.ac.uk//id/eprint/7459/.
Full textAbstract:
A library of novel chiral DMAP derivatives were synthesised from 4-chloropyridine and 3,5-dibromo-4-chloropyridine to give a diverse range of DMAP derivatives focusing on modifications at the 3-position and 3,5-positions of pyridine in DMAP. Characteristics were included in the catalyst design to allow for the formation of intramolecular cation-π interactions, which were studied with fluorescence spectroscopy. In order to achieve the desired catalyst structure, methodology was developed to allow for the facile syntheses of a diverse range of hydrocinnamaldehydes, which were subsequently used in optimised synthetic routes towards the DMAP derivatives. The synthesised catalysts were studied in the kinetic resolution of secondary alcohols, leading to enantioenrichment of the ester and the remaining alcohol. Attempts were made to probe the pyridinium intermediate using fluorescence spectroscopy, with characteristic cation-π fluorescence responses observed when the catalysts were both alkylated and acylated.
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Weber, Verena. "Plasmonic nanostructures for the realization of sensor based on surface enhanced Raman spectroscopy." Doctoral thesis, Università degli studi di Padova, 2014. http://hdl.handle.net/11577/3423838.
Full textAbstract:
The field of Plasmonics deals with interaction processes between an electromagnetic radiation of appropriate wavelength and the conduction electrons of a metal. The induced collective oscillation of the electrons is called Plasmon Resonance. The Localized Surface Plasmon Resonance (LSPR) occur when the excitation involves surface electrons of nanostructures with dimensions less or comparable to the excitation wavelength. The excitation causes a strong enhancement of the local field around the metal nanostructure, which, combined with Raman Spectroscopy, could be very interesting for molecular sensing. The Raman technique is well known for providing a fingerprint spectrum of a given molecule, but has the great limitation of low sensibility. By adsorbing the analyte of interest on a plasmonic substrate in the region of enhanced local field, high detection sensitivity can be reached through Surface Enhanced Raman Spectroscopy (SERS).
The first part of the present work is focused on the synthesis and characterization of gold and silver nanoparticles (Au and Ag NPs) and gold nanoshells (Au NSs) and their exploitation for the realization of SERS substrates, both in colloidal solutions and on solid supports. Different metal nanostructures give the possibility to exploit the LSPR in a wide spectral range, from the Vis to the near IR. Their optical and morphological characterization is carried out with conventional techniques, like TEM, AFM, UV-Vis absorption and Surface Enhanced Raman Spectroscopy, and with a new characterization technique, rarely used in this research field: the Photoacoustic Spectroscopy. It provides information about the absorption contribution to the total extinction of a plasmonic nanostructure. From a rigorous measurement of the SERS enhancement factor and from Photoacoustic Spectroscopy data at different excitation wavelengths, some considerations could be done concerning the relation of far field extinction and near field SERS properties. SERS EF profile measurements on liquid and solid SERS substrates demonstrated the presence of hot spots. The solid SERS substrates were chemically stable, homogeneous and reproducible and showed EF values of about 104-105. In colloidal solution, the EF values were about 103-106, depending on the metal nanostructure. Photoacoustic measurements performed on Au NSs in solution were in agreement with theoretical predictions found in literature.
In the second part of the work, the plasmonic substrates, realized with Au NPs and Au NSs, were used for the realization of label free SERS sensors, to detect toxic aromatic chemical species and biological molecules. A sensor for toxic volatile compounds, based on Au NPs and Au NSs substrates coupled with a porous organic-inorganic hybrid sol-gel matrix, was realized. The matrix was specifically chosen for exhibiting a high-affinity interaction to aromatic hydrocarbons. The enhancement activity of the Au NPs and Au NSs substrates on the sol gel matrix alone was demonstrated. Some problems in the xylene detection process through SERS were probably due to the fast matrix regeneration under the laser radiation. Although, the enhanced SERS efficiency due to the detection design was demonstrated.
Another application was based on the development of a novel label-receptor system, based on the cromophore 4-hydroxyazobenzene-2 carboxylic acid (HABA) and its specific antibody, to be used in bio-analytical applications. The interesting behaviour of the HABA dye relies in changing its tautomeric structure from an azo to a hydrazo form, thanks to the interaction with its antibody. This structural change can be exploited for SERS detection of the label-receptor interaction. Properly synthesized and characterized HABA derivatives were adsorbed onto SERS substrates, further incubated in the antibody solution. The HABA signals were well visible on both Au NSs and Au NPs substrates. No HABA change could be detected through SERS, because the antibodies extracted in vivo from two rabbits, do not cause the quantitative change of the HABA structure.<br>La Plasmonica si occupa dell’interazione di una radiazione elettromagnetica di opportuna lunghezza d’onda con gli elettroni di conduzione di un metallo. L’oscillazione collettiva degli elettroni, indotta da questa interazione, è chiamata appunto Risonanza Plasmonica. La risonanza plasmonica di superficie localizzata avviene quando gli elettroni coinvolti sono quelli di superficie di un metallo nanostrutturato con dimensioni minori o comparabili alla lunghezza d’onda di eccitazione. Da questa eccitazione deriva una forte amplificazione del campo elettromagnetico locale, localizzato nelle immediate vicinanze della nanostruttura metallica. Tale amplificazione, unita a una tecnica di rivelazione spettroscopica specifica, quale la spettroscopia Raman, può essere sfruttata per la realizzazione di sensori molecolari. La tecnica Raman è conosciuta come altamente specifica, perché in grado di fornire uno spettro caratteristico della singola molecola, identificandone univocamente la presenza e la costituzione. La sua maggiore limitazione, però, è la bassa sensibilità. Ponendo l’analita in prossimità di un substrato plasmonico, proprio nella regione di forte amplificazione del campo locale, la sensibilità di rivelazione viene fortemente aumentata, dando origine alla spettroscopia Raman amplificata da superfici (SERS).
La prima parte del presente lavoro è focalizzata sulla sintesi e sulla caratterizzazione di nanoparticelle d’argento, d’oro e di nano gusci d’oro (chiamati nanoshell) e sul loro impiego per la realizzazione di substrati SERS, sia in soluzione colloidale che su substrato solido. L’utilizzo di differenti nanostrutture metalliche, dà la possibilità di sfruttare la risonanza plasmonica localizzata di superficie in un’ampia regione spettrale, che si estende dal visibile al vicino infrarosso. La caratterizzazione ottica e morfologica delle nanostrutture è stata effettuata con tecniche convenzionali, come la spettroscopia di assorbimento UV-visibile, il SERS, la microscopia elettronica a trasmissione e la microscopia a forza atomica. Ad esse è stata affiancata anche una tecnica raramente usata nell’ambito della plasmonica: la spettroscopia fotoacustica. Questa può fornire informazioni riguardanti il contributo di assorbimento, all’estinzione totale, di una nanostruttura plasmonica. Da una rigorosa misura dei fattori di amplificazione e delle proprietà di fotoacustica al variare della lunghezza d’onda, possono essere fatte alcune considerazioni riguardanti la possibile relazione tra l’estinzione (proprietà di campo lontano) e l’ amplificazione SERS (proprietà di campo vicino). Le misure dei profili di eccitazione SERS su substrati plasmonici in liquido e su supporto solido, hanno evidenziato la presenza di hot spots, ovvero di zone fortemente amplificate dall’interazione di due o più nanostrutture.
I substrati SERS solidi sono risultati chimicamente stabili, omogenei e riproducibili; essi presentano valori di fattori di amplificazione attorno a 104-105. In soluzione colloidale, i fattori di amplificazione delle nanostrutture hanno raggiunto valori nell’intervallo 103-106, dipendentemente dal tipo di nanostruttura metallica investigata. Le misure di fotoacustica effettuate su soluzioni colloidali di nanoshell d’oro si sono rivelate in accordo con le predizioni teoriche di letteratura.
Nella seconda parte del lavoro, i substrati plasmonici, realizzati principalmente con nanoparticelle e nanoshell d’oro, sono stati impiegati per la realizzazione di sensori SERS per la rivelazione di specie chimiche e biologiche.
É stato realizzato un sensore di composti tossici aromatici volatili, accoppiando un substrato plasmonico con un film poroso di sol gel ibrido organico-inorganico. La componente organica della matrice sol gel è stata appositamente scelta per la sua alta affinità a composti aromatici, quali lo Xilene. È stata dimostrata l’amplificazione dei segnali della matrice da parte della componente plasmonica, ma si sono riscontrati alcuni problemi nella rivelazione delle molecole di analita attraverso il SERS. La difficoltà nella rivelazione è probabilmente dovuta al veloce deadsorbimento dello Xilene dalla matrice a causa del forte riscaldamento locale causato dalla radiazione laser. Nonostante questo, si è comunque dimostrata l’aumentata efficienza del sensore progettato, rispetto ai suoi componenti singoli.
La seconda applicazione studiata ha riguardato la realizzazione di un sistema analita-accettore innovativo, che può essere utilizzato per diverse applicazioni bioanalitiche; esso è basato sull’interazione tra un cromoforo diazobenzenico (HABA) e il suo anticorpo specifico. Alla base dell’applicazione si trova una proprietà interessante del suddetto cromoforo, che è quella di cambiare la sua struttura molecolare, passando da una forma azo alla forma idrazo, dopo aver interagito con il suo anticorpo specifico. Questa variazione nella struttura molecolare può essere sfruttata per la rivelazione dell’avvenuta interazione analita-accettore, mediante SERS. Alcuni derivati di questo cromoforo sono stati sintetizzati e caratterizzati in modo da poter essere adsorbiti su un substrato SERS, che viene successivamente incubato in una soluzione di anticorpo. I segnali SERS della molecola di HABA sono risultati ben visibili sia sui substrati di nanoparticelle che di nanoshell d’oro. Purtroppo non è stato possibile rivelare la variazione strutturale del cromoforo, in quanto gli anticorpi, estratti in vivo da due coniglietti, inducono solo un parziale cambio di struttura, rendendo la rivelazione SERS alquanto difficile.
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Angiola, Marco. "Gas sensing properties of carbon nanostructures." Doctoral thesis, Università degli studi di Padova, 2016. http://hdl.handle.net/11577/3424809.
Full textAbstract:
This work is aimed to evaluate the optical gas sensing properties of carbon nanomaterial. In particular it is focused on two materials, Carbon Nanotubes (CNTs) and Graphene Oxide
(GO).
The comprehension of the mechanisms of interaction of these materials with the gas molecules is fundamental for a future application of these materials as sensors targeted to a
specific specie or capable to distinctly detect several dangerous species. On this purpose nanostructures based on GO and CNTs have been produced and tested as optical gas sensors toward oxidizing/reducing gases (H2, CO, NO2) and aromatic volatile Organic Compounds (benzene, toluene, xylene).
Gold nanoparticles (Au NPs) have been used as optical probe thanks to the peculiar Localized Surface Plasmon Resonance feature in the visible range, which is extremely
sensitive to the variation in optoelectronic properties of the surrounding media, such as refractive index and the variation in charge carrier involved in plasmonic excitation in the Au NPs.
Not only amplify the Au NPs the variation in optoelectronic properties of the layer of carbon nanomaterial, but also the electromagnetic coupling with carbon nanomaterials may induce
an enhancement in response and a lowering of the limit of detection of the sensors to the target species.
Moreover, the GO and CNTs are provided of a large possibility of functionalization, which can be used to tailor the gas sensing properties of the nanostructures toward specific species.
CNTs have been combined with the Au NPs, Pd NPs, Ni NPs and fullerenes. Pd and Au NPs increase the response toward H2
, meanwhile Ni NPs and fullerenes appear specific to CO. It
is also suggested the opportunity to monitor the features of the absorbance plot of fullerenes and CNT in the NIR as optical probes, with the carbon nanomaterials playing both the role
of sensing element and optical probe.
The presence of the different functional groups in GO was investigated. The increase in sp2conjugation has a profitable effect for the sensing of H2. Instead, the removal of the oxidized
functional groups hinder the response of the films toward CO and NO2.
The reduction and functionalization of the GO with para- Phenylene Diamine induces the detection of NH3without Au NPs as optical probe. The sensors produced are characterized by high transparency in the visible range and may be incorporated as non-invasive sensors on transparent surfaces.
Most of the sensors worked at 150°C and 300°C. Test of gas sensing have been conducted at low temperatures, at 80°C for CNTs in fullerene matrix and good results were achieved. The
possibility of sensors active at room temperature is suggested by the positive tests conducted with CMG, paving the way for future developments in active optical material sensitive to
gases at room temperature.<br>Il presente lavoro è focalizzato sullo studio di sensori ottici basati su nanomateriali di carbonio, nell’ottica di un’applicazione di questi materiali come sensori di gas. Il lavoro prende in analisi due materiali, i nanotubi di carbonio (CNTs) e il grafene ossido (GO).
La comprensione dei meccanismi di interazione di questi materiali con le molecole di gas è fondamentale per le applicazioni future di questi materiali nel rilevamento di diverse specie nocive di gas. A tal proposito, nanostrutture a base di GO e CNTs sono state sviluppate e studiate come sensori ottici verso gas ossidanti-riducenti (H2, CO, NO2) e nei contronti di
composti volatili organici aromatici (benzene, toluene, xylene).
Le nanoparticelle di oro sono state utilizzate come sonde ottiche grazie alla loro peculiare caratterista di risonanza plasmonica di superficie localizzata, la quale è estremamente sensibile alle variazioni di proprietà ottico-elettroniche del mezzo che le circonda, come l’indice di rifrazione, e alle variazione di densità di portatori di carica che sono coinvolti nell'eccitazione plasmonica nelle nanoparticelle di oro.
Quindi, le nanoparticelle di oro, non solo amplificano le variazioni optoelettroniche del film di nanomateriali di carbonio a cui sono state accoppiate, ma interagiscono con questi
inducendo un miglioramento della risposta ai gas e un abbassamento del limite di rilevamento ai gas in analisi.
Inoltre, GO e CNTs presentano una vasta gamma di possibili funzionalizzazioni, che, possono essere sfruttate per una progettazione mirata delle proprietà di gas sensing delle nanostrutture di carbonio.
I CNTs sono stati abbinati a nanoparticelle di Au, Pd, Ni e a fullereni. Pd e Au portano ad un miglioramento delle prestazioni dei sensori verso il gas H2, nanoparticelle di Ni e fullereni
sembrano avere un’azione specifica verso il gas CO.
In questo lavoro viene anche suggerita la possiblità di monitorare le proprietà di assorbanza di fullereni e CNTs nel range del vicino IR. I CNTs, in tal caso, avrebbero la duplice
funzione di sonde ottiche e di materiale sensibile.
Oltre all'effetto delle nanoparticelle di oro sulle proprietà di gas sensing del GO, è stata valutata l’influenza dei diversi gruppi funzionali. L’estensione dei domini sp2 sembra
favorire il rilevamento di H2, mentre una forte rimozione di gruppi funzionali inibisce la risposta del GO verso CO e NO
2.
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Powell, Alexander. "Engineering plasmonic light scattering with thin dielectric films : towards enhanced light trapping and novel sensing elements." Thesis, University of Oxford, 2015. https://ora.ox.ac.uk/objects/uuid:c18025ef-a693-441d-bd88-e37ebc09b6a5.
Full textAbstract:
Plasmonic research is becoming increasingly focused on the integration of noble metal nanostructures with planar devices to enhance their performance. Whilst the physics of noble metal nanoparticles at a simple interface is well studied, their behaviour inside a thin film structure is not. This work investigates the effect that placement in a thin dielectric film has on the excited modes and the directional scattering from various geometries of nanoparticle; the focus is on the fundamental principles but the application of this work in light trapping and nanoantenna design is also discussed. Research is conducted using finite-difference time-domain simulations and a custom built dark-field Fourier-space microscope, designed to interrogate individual particles and measure their angular scattering in thin films for the first time. It is found that the excited modes, large angle scattering and substrate coupling of the nanoparticles can be manipulated and improved considerably through careful choice of the materials and dimensions of the layers. Scattering from silver nanowires into a substrate is observed experimentally for the first time and an overcoating thin film is exploited to create highly directional emission, which is compared with nanoantennas in the literature. The potential to use this system as a novel sensing element is discussed. Following on from this, the nanocube patch antenna system is reviewed and its operation as a subwavelength plasmonic gas sensor is demonstrated for the first time to test for relative humidity using the Nafion polymer. This easily fabricable system shows superior sensitivities to other single-particle sensors across a range of humidities and simulations predict that by using sharper cubes and different deposition processes a further tripling of the recorded efficiency is achievable. The nanopatch structure can be readily adapted to detect a variety of other gases, and has the potential for integration into photonic circuitry.
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Hugall, James T. "On the nature of SERS from plasmonic nanostructures." Thesis, University of Cambridge, 2013. https://www.repository.cam.ac.uk/handle/1810/267496.
Full textAbstract:
The nature of surface-enhanced Raman scattering (SERS) on nanostructured surfaces is explored using both inorganic and organic-based systems and a variety of environmental perturbation mechanisms. Experimental optical characterisation systems are developed and existing systems extended to facilitate this exploration. SERS of inorganic semiconducting quantum dots (QDs) is observed for the first time, paving the way for their use as spatially well-defined SERS markers. Tuning of the Raman excitation wavelength allows comparison between resonance and nonresonance QD SERS and identifies enhancement due to the plasmonic nanostructure. A gentle mechano-chemical process (carbon dioxide snow jet) is used to rearrange adsorbed organic thiol monolayers on a gold plasmonic nanostructure. The necessity of nanoscale roughness to the large SERS enhancement on pit-like plasmonic nanostructures is shown and demonstrates a new method to boost SERS signals (> 500 %) on plasmonic nanostructures. A multiplexed time-varied exposure technique is developed to track this molecular movement over time and highlights the different origins of the SERS peak and its accompanying background continuum. Using low-temperature cryogenics (down to 10 K) the SERS peak and background continuum intensity are shown to increase as the plasmonic metal damping reduces with temperature. Temperature dependent measurements of QD (resonance) SERS are shown to have strong wavelength dependence due to the excitonic transitions in QDs. Changes to the QD fluorescence at low temperature allows striking comparison between the Raman and fluorescence processes. The role of charge transfer and electromagnetic enhancement in the SERS intensity of p-aminothiophenol (pATP) is investigated on nanostructured plasmonic surfaces coupled to metallic nanoparticles. The results support the importance of charge transfer effects to the SERS of pATP, and highlight the difference between those of electromagnetic origin. Addition of nanoparticles to the nanostructured surface was seen to enhance SERS signals by up to 100×.
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Wezenberg, Sander Johannes. "Exploring metallosalen complexes in materials science and catalysis." Doctoral thesis, Universitat Rovira i Virgili, 2011. http://hdl.handle.net/10803/37357.
Full textAbstract:
Los complejos “metalosalen” [salen = N,N’-bis(salicilideno)etilendiamina] han sido objeto de estudio en la catálisis homogénea y últimamente también en la ciencia de materiales y catálisis multimetálica. En cuanto a esto, hemos explorado el potencial de los complejos “salfen” [N,N’-bis(salicilideno) fenilendiamina] centrados en Zn(II) como componente en el desarrollo de nuevos materiales y sistemas multimetálicos. Los primeros capítulos de esta tesis proporcionan una mejor comprensión sobre las propiedades de estos complejos y esto es seguido por aplicación como detector quiral y estudios de comportamiento de autoensamblaje. Los últimos capítulos se centran en sistemas metalosalen multimetálicos mediante enfoques supramolecular y covalente para su aplicación en la catálisis cooperativa. Este tesis demuestra el potencial de los compuestos salen para su aplicación en ciencia de materiales y catálisis cooperativa.<br>Metallosalen complexes [salen = N,N’-bis(salicylidene)ethylenediamine] have been well-studied in homogeneous catalysis and lately reveive inceasing interest in materials science and multimetallic catalysis. In view of this, we have explored the potential of Zn(II)-centered salphen [N,N’-bis(salicylidene)phenylenediamine] complexes as a building block in the development of new materials and multimetallic systems. The first chapters of this thesis provide a better understanding of the properties of these complexes and this is followed by application as a chiral sensor and studies of their self-assembly behavior. The last chapters focus on multimetallic metallosalen systems for application in cooperative catalysis using supramolecular and covalent approaches. This thesis illustrates the potential of metallosalen complexes for application in materials science and cooperative catalysis
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Zhao, Jun [Verfasser], and Harald [Akademischer Betreuer] Giessen. "Large-area low-cost fabrication of complex plasmonic nanostructures for sensing applications / Jun Zhao. Betreuer: Harald Giessen." Stuttgart : Universitätsbibliothek der Universität Stuttgart, 2015. http://d-nb.info/1069533262/34.
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Yang, Sheng-Chieh, Ji-Ling Hou, Andreas Finn, Amit Kumar, Yang Ge, and Wolf-Joachim Fischer. "Synthesis of multifunctional plasmonic nanopillar array using soft thermal nanoimprint lithography for highly sensitive refractive index sensing." Royal Society of Chemistry, 2015. https://tud.qucosa.de/id/qucosa%3A36330.
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A low-cost plasmonic nanopillar array was synthesized using soft thermal nanoimprint lithography, and its sensitivity was determined through far-field spectroscopic measurements. Its transmission spectrum was highly dependent on the refractive index of the surrounding medium, with its sensitivity being 375 nm per refractive index unit according to the spectral shift. Moreover, a simple sensor whose reflected color changed with a change in the plasma frequency on varying the surrounding medium was fabricated.
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MANZATO, GIACOMO. "Development of multi-functional nanostructured membranes for airborne particles collection, fluidic sensing and co-localized plasmonic enhancement." Doctoral thesis, Università degli studi di Genova, 2022. http://hdl.handle.net/11567/1088143.
Full textAbstract:
The search for new methods enabling efficient collection of particulate matter and
multifactorial analysis in terms of size distribution, elemental composition, and structural
identification represents a key-aspect of current efforts in environmental science.
In this thesis a significant part of the effort has been devoted to the problem of collection
and concentration of airborne particulate matter on a miniaturised custom chip. For this
purpose, I applied original nanofabrication approaches derived from nanotechnology to
build a special Si3N4 sieve, capable of trapping the airborne micro- and nano-particles on the
active region of custom modified free standing TEM membranes. In addition to this, by
fabrication of nanophotonic structures on the active surface of chip concentrators, I studied
the possibility to achieve co-localised and spatially resolved detection of submicrometric
airborne particles, with high resolution and sensitivity. The results demonstrate that with the
new prototype it is possible to investigate not only the concentration, size, and shape of
collected particles, but also their chemical composition (via EDX spectroscopy) and molecular
structure (via Raman spectroscopy).
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Mercurio, James M. "Interlocked host structures for anion recognition and metal nanoparticles for catalysis and sensing applications." Thesis, University of Oxford, 2014. http://ora.ox.ac.uk/objects/uuid:40178988-4945-4a98-af98-59a1a35a12d5.
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This thesis describes the synthesis and anion recognition properties of a variety of interlocked host receptors and the application of metal nanoparticles in the areas of catalysis and sensing. <b>Chapter One</b> introduces the field of anion supramolecular chemistry, with particular emphasis on areas relevant to the research discussed in later chapters. Following this, the synthesis and applications of metal nanoparticles are outlined. <b>Chapter Two</b> details the synthesis of a range of halo-triazolium based rotaxanes and explores the effects of altering both the halogen bond donor atom and degree of preorganisation on the anion recognition properties of the interlocked host system. A halogen bond containing catenane is also prepared and its anion binding properties investigated. <b>Chapter Three</b> initially reports the anion-templated synthesis of a series of neutral pyridine N-oxide axle containing rotaxanes before their ability to recognise anions in aqueous solvent mixtures is studied. Attempts to enhance anion binding through the incorporation of a positive charge into the macrocyclic component of the rotaxane structure are also explored. <b>Chapter Four</b> outlines the preparation of β-cyclodextrin functionalised metal nanoparticles and investigations of their catalytic and sensing properties. <b>Chapter Five</b> describes in detail the synthetic and analytical procedures discussed in chapters two to four. <b>Chapter Six</b> summarises the conclusions of this thesis.
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Khan, Assad Ullah. "Thin-Film Polymer Nanocomposites Composed of Two-Dimensional Plasmonic Nanoparticles and Graphene." Diss., Virginia Tech, 2019. http://hdl.handle.net/10919/101942.
Full textAbstract:
Plasmonic polymer nanocomposites contain plasmonic nanoparticles that are dispersed within a polymer. The polymer matrix strongly influences the optical properties of plasmonic nanoparticles. It is imperative to understand the interaction between plasmonic nanoparticles and polymers so that one can develop functional devices using nanocomposites. The utilization of plasmonic nanoparticles as fillers has great potential to transform critical nanotechnologies where light management is crucial, such as refractive index based nanosensors, optical coatings, and light actuated devices. Despite the great potential, effective integration of plasmonic nanoparticles with polymers remains challenging. This dissertation presents i) the effects of dielectric media on the optical properties of plasmonic nanoparticles, ii) the sensing of polymer brush formation on nanoparticles, iii) the fabrication of plasmonic nanocomposite thin-films with controlled optical properties, and iv) the development of electrically conductive membranes for electrostatic speakers.
The optical response of plasmonic nanoparticles (referred to as wavelength of localized surface plasmon resonance, λLSPR) is sensitive to changes in refractive index of the medium. The sensitivity (S) plays a critical role in determining the performance of nanoparticles in sensing applications. In this dissertation, I have conducted a systematic study on the sensitivity of plasmonic nanoparticles as a function of various parameters: shape, size, composition, initial plasmonic resonance wavelength, cross-sectional area, and aspect ratio. Among the parameters investigated, aspect ratio (R) is determined to be the key parameter that controls S, following an empirical equation, S = 46.87 R + 109.37. This relationship provides a guideline for selecting fillers in plasmonic polymer nanocomposites, and it predicts the final effect of plasmonic nanoparticles on the optical properties of polymer nanocomposites.
Plasmonic nanoparticles are employed to probe polymer grafting on the surfaces of metal nanoparticles. Using ultraviolet-visible (UV-vis) spectroscopy, I have demonstrated the quantification of polymer grafting density on the surface of plasmonic nanoparticles. The λLSPR of plasmonic nanoparticles red-shifts as the polymer concentration near the nanoparticle surface increases. I have investigated the formation of polymer brush by grafting the nanoparticles with thiolated polyethylene glycol (PEG-SH) and revealed the three–regime kinetics in situ. Importantly, this study suggests that a latent regime arises due to fast polymer adsorption and prolonged chain rearrangement on nanoparticle surfaces. When the polymer chains rearrange and chemically tether to the surface, they contract and allow more polymer chains to graft onto the particle surface until saturation. This analytical method provides a new surface probing technique for polymer brush analysis, complementary to conventional methods such as quartz crystal microbalance, atomic force microscope, and microcantilivers.
Commercial tinted glass employs expensive metalized films to reduce light transmittance but has limited spectral selectivity. To reduce the cost of metalized films and to improve the spectral selectivity, I have employed plasmonic nanoparticles in polymers to fabricate spectral-selective tinted films. First, I have synthesized two-dimensional (2D) plasmonic silver nanoparticles (AgNPs) using multi-step growth. The nanoparticles have a tunable plasmon resonance and provide spectral selectivity. The multi-step growth forgoes polymeric ligands such as poly(vinylpyrrolidone) (PVP) and solely relies on a small molecule sodium citrate. Briefly, small citrate-capped Ag seeds are first grown into small 2D AgNPs. The small 2D AgNPs are then used to grow large 2D AgNPs via multiple growth steps. The PVP-free method allows for fast synthesis of 2D AgNPs with large sizes and tunable plasmon resonance across the visible and NIR region. The 2D AgNPs are integrated with polymers to produce thin-film plasmonic nanocomposites. By controlling the planar orientation of the 2D AgNPs through layer-by-layer assembly, the polymer nancomposites have achieved reduced light transmittance and enhanced reflectance across the visible and NIR range. In contrast to conventional polymer nanocomposites where the AgNPs are randomly oriented, the thin-film polymer nanocomposites exhibit excellent control over nanoparticle density and hence the optical properties, that is, tunable light transmittance and reflectance across the visible and NIR.
Lastly, graphene is used to prepare conductive free-standing polymer thin-films. Graphene, an ultralight weight 2D material with excellent electrical and mechanical properties, has potential for use in thin-film composites essential for photovoltaics, electrostatic speakers, sensors, and touch displays. Current graphene-based composite films contain graphene flakes randomly mixed in a polymer matrix and usually possess poor mechanical and electrical properties. In this dissertation, I have developed thin-film nanocomposites comprised of chemical vapor deposited (CVD) graphene and high-performance polyetherimide (PI). The CVD-grown graphene is polycrystalline, and it cannot be used as a free-standing film. By enforcing the polycrystalline graphene with a thin layer of PI, I have prepared free-standing thin-film composites with a high aspect ratio of 105. Mechanical and electrical property characterization reveals a Young's modulus of 3.33 GPa and a resistance of 200 - 500 Ω across the membrane. A typical spring constant of the membrane is ~387 N/m. Dynamic electromechanical actuation shows that the membrane vibrates at various input frequencies. The polymer/graphene film has excellent acoustic properties, and when used as a speaker membrane, it reduces the electrical power consumption by a factor of 10-100 over the frequency range of 600–10,000 Hz.<br>Doctor of Philosophy
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Jarro, Sanabria Carlos Andrés. "GROWTH OF SILVER NANOPARTICLES ON TRANSPARENT SUBSTRATES FROM LIQUID PRECURSORS: IMPROVEMENTS AND APPLICATIONS." UKnowledge, 2013. http://uknowledge.uky.edu/ece_etds/38.
Full textAbstract:
Interest in controlling the synthesis of silver nanoparticles in colloidal solutions has increased during the last two decades. There is also growing interest in forming layers of silver nanoparticles on substrates, particularly for surface-enhanced Raman spectroscopy applications. However, methods to grow silver nanoparticles directly on substrates have not been studied extensively, and there are few techniques for controlling the size, shape, density, and location of the particles. This work presents a simple and reliable method to photodeposit silver nanoparticles onto transparent substrates. The size, shape and deposition density of the nanoparticles are influenced by the precursor solution, light intensity, and surface modification of the substrate. This allows control of the optical and electrical properties of the nanoparticle films. Furthermore, the particles can be patterned using direct laser exposure, scanning probe methods, and electron-beam lithography. Applications and advantages of this deposition method are proposed and explored.
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Weerathunga, Kaluarachchige Don H. "Metal nanoparticle and semiconductor heterogeneous catalysis for synthetic organic oxidation reactions." Thesis, Queensland University of Technology, 2022. https://eprints.qut.edu.au/228677/1/Kaluarachchige%20Don_Weerathunga_Thesis.pdf.
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This thesis investigated new metal nanoparticle and semiconductor catalyst and photocatalyst systems for achieving fine chemical synthesis from both fossil-fuel sourced reactants and biomass carbohydrate-derived reactants. Photocatalysts for industrially important organic oxidation reactions were developed that efficiently worked with the aid of solar light irradiation, at low temperature and pressure, that avoided the use of hazardous chemicals. The effects on the organic reaction mechanisms of different noble metal nanoparticle and metal oxide nanostructures were explored for these chemical transformations. Success in developing the nanomaterial photocatalysts has contributed to the field of sustainable green chemical synthesis.
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Hajimammadov, R. (Rashad). "Plasmonic, electrical and catalytic properties of one-dimensional copper nanowires:effect of native oxides." Doctoral thesis, Oulun yliopisto, 2018. http://urn.fi/urn:isbn:9789526218878.
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Abstract Recent advances in materials synthesis resulted in a rediscovery of the low cost copper in its one and two-dimensional forms and project newer applications of this metal in fields not considered before. In this thesis, one-dimensional copper, i.e. nanowires are synthesized by a hydrothermal route and explored for their chemical, electrical, catalytic and plasmonic properties with highlighted advantages, benefited from their size and shape compared to thin film and bulk copper. Characterization of copper nanowires and their native oxides were performed using a number of analytical techniques such as X-ray photoelectron and Auger spectroscopy, Raman spectroscopy, X-ray diffraction as well as scanning probe and electron microscopy techniques to elucidate the oxidation mechanism and to assess the feasibility of the oxidized materials for various applications. A few atomic layers of cuprous oxide seem to form on the surface of the nanowires instantly, maybe already during synthesis, which then slowly grows further when exposing the nanowires to ambient air leading to the appearance of cupric oxide as well. Because of the surface oxides, individual nanowires and their bundled networks exhibit semiconducting behavior, which complicates the direct use of such materials for interconnections in electronics. However, even with the presence of native oxides, copper nanowires hold promise in many other applications such as the ones explored here for plasmonics and heterogeneous catalysis. As demonstrated in this work, surface plasmon absorption properties of the nanowires can be exploited for chemical sensing of surface adsorbed molecules (model compound Rhodamine 6G) by efficiently amplifying its Raman spectrum without using any lithographically defined sensor template. Further, it is shown that phenol contamination in water may be efficiently eliminated by converting it to nontoxic polyphenol as well as to CO2 owing to the highly efficient catalytic property of the mixed oxide phases on the surface of the nanowires. The results published in this thesis contribute to the understanding of the chemical and physical behavior of copper nanowires and other low dimensional copper nanostructures that undergo rapid surface oxidation<br>Tiivistelmä Jatkuva elektronisten laitteiden ja anturien pienentäminen on hyvin linjassa teknologian kehittymisen kanssa. Pyrkimys monitoimisiin ja tehokkaisiin materiaaleihin on muuttanut tavanomaisten materiaalien käsitystä. Viimeisimmät edistysaskeleet materiaalisynteesissä ovat johtaneet edullisen kuparin uudelleenlöytämiseen sen yksi- ja kaksidimensionaalisissa muodoissa ennustaen metallille uusia sovellutuksia alueilla, joissa sitä ei ole aiemmin hyödynnetty. Tässä väitöstyössä on tutkittu hydrotermisesti syntetisoitujen yksiulotteisten kuparinanojohtimien kemiallisia, sähköisiä, katalyyttisiä ja plasmonisia ominaisuuksia sekä näiden pieneen kokoon ja muotoon perustuvia etuoja ohutkalvo- ja bulkkikupariin verrattuna. Kuparinanojohtimia ja niiden luonnollisia oksideja karakterisoitiin useilla analyysitekniikoilla kuten röntgenelektroni- ja Auger-eletronispektroskopialla, Raman-spektroskopialla, röntgendiffraktiolla sekä pyyhkäisykärki- ja elektronimikroskopialla selvittäen hapettumismekanismeja ja oksidien soveltuvuutta eri käyttötarkoituksiin. Muutaman atomikerroksen paksuinen kupari(I)oksidikerros havaittiin muodostuvan välittömästi, luultavasti jo materiaalisynteesin aikana nanojohtimien pinnalle. Nanojohtimien altistuessa ympäröivälle ilmalle oksidikerros kehittyi hitaasti johtaen kupari(II)oksidin muodostumiseen. Pintaoksidien johdosta yksittäiset nanojohtimet ja niistä yhteenkasautuneet verkostot käyttäytyvät puolijohdemaisesti mikä monimutkaistaa näiden materiaalien käyttöä sellaisenaan elektroniikan johtimissa. Luonnollisista oksideista huolimatta kuparinanojohtimet ovat lupaavia monissa muissa sovelluksissa, kuten tässä työssä tutkituissa plasmonisessa ja heterogeenisessä katalyysissä. Väitöstyössä osoitetaan, että nanojohtimen pintaplasmonisia absorptio-ominaisuuksia voidaan hyödyntää pintaan absorboituneiden molekyylien kemiallisessa havainnoinnissa (mallinnettu yhdiste rodamiini 6G) vahvistamalla Raman–spektriä käyttämättä lainkaan litografiapohjaista anturisapluunaa. Myöskin vesien fenolikontaminaatio voidaan tehokkaasti muuntaa myrkyttömiksi polyfenoleiksi ja hiiidioksidiksi hyödyntämällä nanojohtimien pinnalla olevia oksideja tehokkaana katalyyttinä (jopa parempi kuin kaupallisten kupariin pohjautuvat katalyytit). Tässä väitöstyössä julkaistut tulokset edistävät kuparinanojohtimien sekä muiden pienikokoisten ja nopeasti hapettuvien kuparinanorakenteiden kemiallisen ja fyysisen käytöksen ymmärtämistä. Tieteellisten kehitysaskeleiden lisäksi tämä väitöstyö voi myös toimia lähteenä pienirakenteisten yleisten metallien sovelluksille
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Niedermayer, Stefan [Verfasser], and Thomas [Akademischer Betreuer] Bein. "Multifunctional mesoporous nanoparticles for catalysis, sensing and drug delivery applications / Stefan Niedermayer. Betreuer: Thomas Bein." München : Universitätsbibliothek der Ludwig-Maximilians-Universität, 2013. http://d-nb.info/1080663274/34.
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Gruber, Benjamin [Verfasser], and Burkhard [Akademischer Betreuer] König. "Functional lipid membranes: Bio-inspired nanomaterials for sensing and catalysis / Benjamin Gruber. Betreuer: Burkhard König." Regensburg : Universitätsbibliothek Regensburg, 2013. http://d-nb.info/1038091993/34.
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