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Dissertations / Theses on the topic 'Plasmonic Nanoparticles(Au, Ag)'

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Published: 7 September 2023

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1

Adamiv, V. T., P. Yu Demchenko, R. M. Dutka, R. V. Gamernyk, Yu O. Kulyk, and I. M. Teslyuk. "Determination of Sizes of Ag Nanoparticles in Glass Li2B4O7:Ag,Gd." Thesis, Sumy State University, 2015. http://essuir.sumdu.edu.ua/handle/123456789/42610.

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Annealing in air and vacuum were obtained glass samples Li2B4O7:Ag,Gd with Ag NPs. Three methods: the half-width strip plasmon resonance, X-ray diffraction and Small-angle X-ray scattering, in these samples by size NPs Ag. Revealed that the size of NPs Ag, defined by half-widths plasmon resonance band much smaller than obtained by other methods. It is concluded that the methods of X-ray diffraction and small-angle X-ray scattering give results closer to reality than the method plasmon resonance.
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2

Pugliara, Alessandro. "Elaboration of nanocomposites based on Ag nanoparticles embedded in dielectrics for controlled bactericide properties." Thesis, Toulouse 3, 2016. http://www.theses.fr/2016TOU30324/document.

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Les nanoparticules (NPs) d'Ag sont très utilisées dans le secteur de la santé, dans l'industrie alimentaire et dans les produits de consommation pour leurs propriétés antimicrobiennes. Le grand rapport surface sur volume des NPs d'Ag permet une augmentation importante du relargage d'Ag comparé au matériau massif et donc une toxicité accrue vis à vis des micro-organismes sensibles à cet élément. Ce travail de thèse présente une évaluation des propriétés antimicrobiennes de petites NPs d'Ag (<20 nm) enrobées dans des matrices de silice sur la photosynthèse d'algues vertes. Deux techniques d'élaboration par voie physique ont été utilisées pour fabriquer ces nanocomposites: (i) l'implantation ionique à basse énergie et (ii) la pulvérisation d'Ag couplée avec la polymérisation plasma. Les propriétés structurales et optiques de ces nanostructures ont été étudiées par microscopie électronique à transmission, réflectivité et ellipsométrie. Cette dernière technique, couplée à un modèle basé sur l'approximation quasi-statique de type Maxwell-Garnett, a permis la détection de petites variations dans la taille et la densité des NPs d'Ag. Le relargage d'argent de ces NPs d'Ag enrobées dans des diélectriques a été mesuré par spectrométrie de masse après immersion dans de l'eau tamponnée. La toxicité à court terme de l'Ag sur la photosynthèse d'algues vertes, Chlamydomonas reinhardtii, a été évaluée par fluorométrie. L'enrobage des nanoparticules dans un diélectrique réduit leur interaction avec l'environnement, et les protège d'une oxydation rapide. La libération d'Ag bio-disponible (impactant sur la photosynthèse des algues) est contrôlée par la profondeur à laquelle se trouvent les NPs d'Ag dans la matrice hôte de silice. Cette étude permet d'envisager le design de revêtements à effet biocide contrôlé. En couplant les propriétés antimicrobiennes de ces NPs d'Ag enrobées à leur qualité d'antenne plasmonique, ces nanocomposites peuvent être utilisés pour détecter et prévenir les premières étapes de la formation de biofilms sur des surfaces. Ainsi, une dernière partie de ce travail est dédiée à l'étude de la stabilité et de l'adsorption de protéines fluorescentes Discosoma rouges recombinantes (DsRed) sur ces surfaces diélectriques avec la perspective du développement de dispositifs SERS
Silver nanoparticles (AgNPs) because of their strong biocide activity are widely used in health-care sector, food industry and various consumer products. Their huge surface-volume ratio enhances the silver release compared to the bulk material, leading to an increased toxicity for microorganisms sensitive to this element. This work presents an assessment of the biocide properties on algal photosynthesis of small (<20 nm) AgNPs embedded in silica layers. Two physical approaches were used to elaborate these nanocomposites: (i) low energy ion beam synthesis and (ii) combined silver sputtering and plasma polymerization. These techniques allow elaboration of a single layer of AgNPs embedded in silica films at defined nanometer distances (from 0 to 7 nm) beneath the free surface. The structural and optical properties of the nanocomposites were studied by transmission electron microscopy, reflectance spectroscopy and ellipsometry. This last technique, coupled to modelling based on the quasi-static approximation of the classical Maxwell-Garnett formalism, allowed detection of small variations over the size and density of the embedded AgNPs. The silver release from the nanostructures after immersion in buffered water was measured by inductively coupled plasma mass spectrometry. The short-term toxicity of Ag to the photosynthesis of green algae, Chlamydomonas reinhardtii, was assessed by fluorometry. Embedding AgNPs reduces their interactions with the buffered water, protecting the AgNPs from fast oxidation. The release of bio-available silver (impacting on the algal photosynthesis) is controlled by the depth at which AgNPs are located for the given host silica matrix. This provides a procedure to tailor the biocide effect of nanocomposites containing AgNPs. By coupling the controlled antimicrobial properties of the embedded AgNPs and their quality as plasmonic antenna, these coatings can be used to detect and prevent the first stages of biofilm formation. Hence, the last part of this work is dedicated to a study of the structural stability and adsorption properties of Discosoma recombinant red (DsRed) fluorescent proteins deposited on these dielectric surfaces with perspectives of development of SERS devices
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CALEFFI, MATTEO. "Deposizione di nanoparticelle core-shell di Ag@MgO e Au@MgO su TiO2 meso-poroso mediante sorgente di aggregazione di nanoparticelle: una strategia per migliorare l'efficienza di Celle Solari di Perovskite." Doctoral thesis, Università degli studi di Modena e Reggio Emilia, 2022. http://hdl.handle.net/11380/1271921.

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Attualmente, l'accoppiamento fra nanoparticelle metalliche (NP) e materiali foto-attivi rappresenta una via promettente per migliorare le efficienze di dispositivi in applicazioni di fotocatalisi ed energia solare. Nella maggior parte dei casi, il miglioramento dell'efficienza dei dispositivi solari mediante funzionalizzazione con NP core-shell è stato ottenuto attraverso metodi chimici sia per la sintesi che per la deposizione delle NP. Questi metodi sono limitati nella combinazione di materiali di core e shell, così come alcuni inconvenienti legati all'uso di solventi. D'altra parte, le sorgenti di aggregazione di NP basate su magnetron-sputtering, rappresentano un approccio versatile per depositare NP su superfici, con controllo preciso sulle quantità e sulle dimensioni medie, consentendo di ottenere strutture core-shell e/o NP metalliche incorporate in una matrice ultrasottile. Durante il mio progetto di dottorato, esploro le potenzialità nell'applicazione di questa tecnica alle celle solari di perovskite (PSC), con l'obiettivo di studiare le proprietà dei substrati funzionalizzati e di migliorarne l’assorbimento della luce e l'efficienza (PCE). In particolare, le NP core-shell Ag@MgO e Au@MgO vengono depositate sullo strato mesoporoso di TiO2, in PSC a triplo catione. Sono stati considerati ricoprimenti diversi di NP che variano tra l'1 e il 25% e le proprietà strutturali e morfologiche dei substrati funzionalizzati sono state caratterizzate combinando informazioni ottenute da HRTEM, EDX, SEM, AFM e XPS. La struttura delle NP di Ag@MgO è studiata mediante HRTEM ed EDXS, mostrando che il core di Ag presenta una struttura icosaedrica multi-dominio e dimostrando che la crescita di MgO è localizzata attorno ai nuclei di Ag, confermando l’ottenimento di una struttura core-shell. Le proprietà morfologiche delle NP, ad es. le dimensioni laterali e l'altezza, sono determinate rispettivamente tramite SEM e AFM. L'altezza media delle NP H è stimata intorno a 4 nm per le NP di Ag@MgO, e intorno a 6 nm per quelle di Au@MgO, mentre per entrambi i sistemi la dimensione laterale media D è di circa 8 nm. Quest'ultima aumenta in funzione del ricoprimento, cosicché le NP sono caratterizzate da un rapporto D/H variabile tra 1 e 2. Sia per le NP di Ag che per quelle di Au, gli esperimenti di stabilità termica fino a 150°C sono stati monitorati mediante XPS e dimostrano il ruolo benefico svolto da MgO nel preservare la stabilità termica delle NP ed evitarne l'ossidazione. Le trasmissività UV-Vis (T) e le riflettività (R) dei substrati e di quelli arricchiti con NP sono misurate con uno spettrofotometro, determinandone la Optical Loss differenziale (ΔL) per diversi ricoprimenti di NP. Gli spettri ottici dei campioni contenenti Ag@MgO rivelano un picco a 430 nm. Le simulazioni di polarizzabilità delle NP basate su Maxwell-Garnett confermano che il picco è correlato all'assorbimento del LSPR di Ag, mentre la sua posizione dipende dal rapporto D/H. Gli spettri ottici di campioni contenenti Au@MgO rivelano un picco più largo, a 520 nm, mostrando - in accordo con la letteratura e con i risultati delle simulazioni - che la banda di LSPR è più grande che nel caso di NP di Ag. Come ultima fase, viene esaminato l’effetto delle NP di Ag@MgO e Au@MgO nelle PSC. Vengono testati dispositivi con diverso ricoprimento superficiale tra 0 e 25% e per diversi spessori nominali della shell tra 2,5 e 0,6 nm. Per le PSC arricchite con NP di Ag@MgO, il ricoprimento ottimale è di 1,5%, che porta ad un aumento dell’efficienza dei dispositivi del 5%, fino al 17,8%, correlato con l’aumento di JSC e di VOC. D'altro canto, le misure preliminari relative all'incorporazione di NP Au@MgO nelle PSC non hanno determinato un aumento dell'efficienza e meritano ulteriori indagini.
Nowadays, coupling of Metal nanoparticles (NPs) with photo-active materials represents a promising route to enhance device performances in photocatalysis and solar energy applications. In most cases, efficiency improvement in photovoltaic devices by core-shell NP functionalization was obtained via chemical wet methods for both core and shell synthesis and deposition. These methods – though readily suitable for scalability – presents some limitations in combining NP and shell materials, as well as some drawbacks related to the use of solvents. On the other hand, nanocluster aggregation sources based on magnetron-sputtering represent a versatile route to deposit NPs on any selected surface, with precise control of both their quantity and average dimension. Moreover, co-deposition techniques allow to obtain core-shell structures and/or metal NPs embedded in ultra-thin host matrix. During my PhD project, I explore the potentialities of applying this methodology to Perovskite Solar Cells (PSCs), aiming to investigate the properties of these functionalized substrates and, ultimately, to improve their light harvesting and power conversion efficiency (PCE). In particular, Ag@MgO and Au@MgO core-shell NPs are deposited on the mesoporous TiO2 surface Electron-Transport Layer of triple-cation PSCs. Different NP coverage varying between 1-25% has been considered, and the structural and morphological properties of the functionalized substrate has been fully characterized by combining complementary information obtained by HRTEM, EDX, SEM, AFM and XPS. The Ag@MgO NP core-shell structure is investigated with HRTEM and EDXS, showing that the Ag core presents a multi-twinned icosahedral structure and proving that the MgO growth is preferentially localized around the metal cores, i.e. that a core-shell structure is obtained. Furthermore, NP morphological properties, i.e. their lateral size and height, are determined via SEM and AFM, respectively. The average NP height H is estimated around 4 nm and 6nm for Ag@MgO NPs and Au@MgO NPs, respectively, while for both systems the average lateral size D is found around 8 nm. The latter slightly increases as a function of coverage, so that the NP spheroidal shape is characterized by an aspect ratio D/H varying between 1 and 2. For both Ag and Au NPs, XPS annealing experiments performed in UHV up to 150°C demonstrate the beneficial role played by the MgO shell in preserving their thermal stability and avoiding oxidation. The UV-Vis Transmittivity (T) and Reflectivity (R) of pristine and NP-enriched substrates are measured with a spectrophotometer, thus determining the Differential Optical Loss (ΔL) spectra for different NP coverages. For Ag@MgO NP-enriched samples, spectra reveal an intense and broad band, peaked at 430 nm. NP polarizability simulations based on Maxwell-Garnett approach confirm that the band maximum is related to Ag LSPR absorption, while its position depends on the NP aspect ratio. Au@MgO NP spectra reveal a broader optical loss band, peaked at 520 nm, showing - in agreement with literature and with the results of simulations - that the plasmonic loss band is larger than the case with Ag NPs. As last step, the incorporation of core–shell Ag@MgO and Au@MgO NPs into PSCs is investigated. Devices with different NP surface coverage between 0 and 25% and for different nominal shell thickness between 2.5 and 0.6 nm are tested. For Ag@MgO NP-enriched PSCs, the optimum coverage is 1.5%, which leads to a relative increase of 5% in terms of device efficiencies up to 17.8%, related to an increase in both JSC and VOC. On the other hand, preliminary measures of the incorporation of Au@MgO core-shell NPs in PSCs did not result in an efficiency increase and deserve further investigation.
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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
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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Jouanin, Anthony. "Extraction de la lumière par des nanoparticules métalliques enterrées dans des films minces." Phd thesis, Palaiseau, Institut d'optique théorique et appliquée, 2014. http://pastel.archives-ouvertes.fr/pastel-01061272.

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L'essor des procédés de micro et nano-fabrications rend aujourd'hui accessible la synthèse contrôlée de nanoparticules métalliques (typiquement de 3 à 200nm) offrant de larges résonances d'absorption et de diffusion dont les fréquences peuvent être contrôlées finement en variant judicieusement leur géométrie et leur composition. Dans ce travail de thèse relevant de l'électrodynamique classique établit par Maxwell, nous étudions numériquement l'intérêt de ces particules pour la problématique du (dé)couplage de la lumière piégée dans un film mince diélectrique - une géométrie de référence permettant de rendre compte du phénomène de piégeage qui limite considérablement l'efficacité de dispositifs électroluminescents et de certaines cellules solaires. Pour ce faire, nous proposons quelques règles de conception de nanoparticules capables d'extraire efficacement la lumière piégée. Pour un émetteur seul, environ 20% de la lumière émise est rayonnée hors du guide (rad~0.2). L'ajout d'une monocouche (~50nm d'épaisseur) composée d'un ensemble de particules " optimisées " et aléatoirement positionnées autour de l'émetteur permet d'accroître cette efficacité jusqu'à 70% en moyenne statistique sur le désordre. D'intéressants effets de cohérences liés à la nature du désordre au sein de ladite couche sont également mis en évidence.
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Wood, Christopher. "Non-spherical plasmonic nanoparticles." Thesis, Imperial College London, 2016. http://hdl.handle.net/10044/1/48485.

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The field of nanotechnology has grown exponentially in recent years. As advancements are made in synthetic technology, this allows for their implementation into new research areas, industries, and potential applications. Nanoparticles are an extensively studied area in nanotechnology, with a plethora of constituent materials providing a vast array of potential properties. Plasmonic nanoparticles in particular have the ability to absorb light, leading to enhancements in many applications, for example surface enhanced Raman spectroscopy. Many plasmonic nanoparticle studies are focused on spherical nanoparticles, but significantly less is known of their non-spherical counterparts. Non-spherical plasmonic nanoparticles possess unique optical and behavioural properties that are of significant technological interest. However, their relatively unknown formation mechanisms typically result in polydisperse samples and little being known of their specific behaviour. The work in this thesis is centred on three areas of non-spherical plasmonic nanoparticles. The first is based on silver nanoprisms, synthesised from the photo-conversion of silver seeds. A blue-shift of their dipole excitation after illumination was noted and investigated using UV-Vis and TEM. Nanoprism analogues were synthesised and investigated, including gold-coated, and hollowed prisms. The second area is based on the size-selection of silver nanoprism solutions using ultraconcentration through a liquid-liquid interface. These investigations were to determine whether such methods and which conditions could be used to increase monodispersity of such nanoparticle samples. An increase in mean size indicated a more monodispersed sample was achieved, and if progressed further could significantly improve the results of other sections or future research. The final section studies magnetic nanoparticles, and using magnetism to direct nanoparticles to points of interest on large multifunctional plasmonic substrates. Through these investigations, magnetic trapping was observed of single nanoparticles on pyramidal substrates.
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Gross, Pierre-Alexandre. "Modification de nanotubes de TiO2 pour la production d’hydrogène par photodissociation de l’eau sous lumière solaire." Thesis, Strasbourg, 2014. http://www.theses.fr/2014STRAF053.

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Ce travail de thèse traite de la production d’hydrogène par le procédé de photoélectrocatalyse en utilisant une photoanode à base de nanotubes de TiO2 verticalement alignés. L’utilisation du TiO2 étant limité pour des applications solaires en raison de son large gap, il est nécessaire de le modifier. Deux approches sont proposées pour modifier les nanotubes de TiO2 et leur permettre d’absorber la lumière visible. La première est une modification chimique du TiO2 par co-dopage cationique-anionique (Ta-N) ou (Nb-N). Les cations sont insérés durant la croissance des nanotubes grâce à une approche inédite, et l’azote est inséré durant le traitement thermique. Ceci a pour effet la formation d’orbitales hybrides qui entraîne une réduction du gap et une activité sous lumière visible, tout en permettant une stabilité de la structure. La seconde approche consiste à déposer des nanoparticules d’Ag sur la surface des nanotubes de TiO2. Grâce au contrôle de la morphologie des nanoparticules d’Ag, leur résonnance plasmonique permet de stimuler l’absorption du TiO2 et ainsi d’augmenter son rendement à la fois sous lumière UV et sous lumière visible
This work is about the production of hydrogen by photoelectrocatalysis using a vertically aligned TiO2 nanotubes based photoanode. Utilization of TiO2 for solar applications is limited due to its large band gap, it has to be modified. Two approaches are proposed for the modification of the TiO2 nanotubes to make them absorb visible light. The first one is the chemical modification of the TiO2 by (Ta-N) or (Nb-N) cationic-anionic co-doping. Cations are inserted during the growth of the nanotubes by a novel approach, and nitrogen is inserted during heat treatment. This leads to the formation of hybrid orbitals resulting in a band gap reduction and of activity under visible light. The second approach consists of the deposition of Ag nanoparticles on the surface of the TiO2 nanotubes. Thanks to the control of the morphology of the Ag nanoparticles, their plasmonic resonance can enhance the absorption of TiO2 and thus increase its activity both under UV and visible light
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Adleman, James R. Psaltis Demetri Psaltis Demetri. "Plasmonic nanoparticles for optofluidic applications /." Diss., Pasadena, Calif. : California Institute of Technology, 2009. http://resolver.caltech.edu/CaltechETD:etd-05102009-103332.

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Li, Zhaozhu. "Plasmonic Approaches and Photoemission: Ag-Based Photocathodes." W&M ScholarWorks, 2017. https://scholarworks.wm.edu/etd/1516639865.

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Photocathodes play an important role in present large accelerator facilities by providing polarized or un-polarized electron beams. Current state-of-art high polarization photocathodes consist of strained super-lattice GaAs based photocathodes, e.g. GaAs/GaAsP has a quantum efficiency ~1% and polarization ~90% at near-infrared wavelength for the incident light. Despite the advantages offered by metallic photocathodes regarding longer life time, fast response time and low requirements of ultra-high vacuum environment, they have not been put to use due to their low quantum efficiency, even though one can envision several approaches to achieve spin-polarization from them. A possible solution is to apply the Fano resonance, that involves coupling the surface plasmon resonance and the 1st diffraction order of incident light on a corrugated silver surface. This thesis demonstrates that this approach yields an enhancement of the QE performance of a cesiated silver grating cathode for light incident at the resonance angle, compared to that of a cesiated flat silver cathode measured in the same system. By altering the grating profile through oblique angle deposition (OAD) of a silver thin film onto a grating surface using magnetron sputtering deposition, one can further enhance the Fano resonance and consequently improve the electric field intensity near the silver cathode surface. QE measurements confirm an enhancement of QE (26%) on the cesiated OAD sample compared to a cesiated one obtained under normal deposition(ND) for light incident at resonance, respectively, showcasing a possible road for metallic photocathodes for this application.
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Steven, Christopher R. "Plasmonic metal nanoparticles : synthesis and applications." Thesis, University of Strathclyde, 2017. http://digitool.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=27939.

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Plasmonic metal nanoparticles are widely exploited in academia and industry for use in various assay types. In collaboration with an industrial partner, BBI Solutions, the work here details investigations into the production and use of the plasmonic nanoparticles. The work was split into two themes. The first of these was flow chemistry of nanoparticles, covering a microfluidic assay platform and continuous colloid production. In chapter one, a novel microfluidic assay platform was developed which facilitated the transfer of multiple, sequential bench-top procedures into a single device. This allowed the rapid detection of a sugar binding protein to be demonstrated. The microfluidic system included all pre-detection steps involved in employing the specific aggregation of functionalised silver nanoparticles. Straightforward detection of the protein was demonstrated at concentrations lower than those achieved using comparable methods in the literature. In the second chapter, a novel bench-top scale continuous reactor for the production of gold nanoparticles was developed. It was found that the continuous stirred tank reactor was generally unsuitable for this synthesis. A laminar tubular reactor was more successful but fouling of the reactor material was a significant obstacle to production of good quality colloid. In both cases, nanoparticles produced in a batch synthesis were of more consistent quality. This suggested that further work was needed to develop a competitive continuous production method. The second research theme was development of a novel nanoparticle assembly assay, based on DNA assembly. In chapter three it was found that current tools for the understanding of dynamic DNA structure were limited. This led to the first use of an existing coarse grain model to determine thermodynamic properties of DNA assembly. Analysis showed that the results were comparable with the best simulation models shown in the literature, while being generated much more quickly and at less computational expense.
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MULTARI, CRISTINA. "Magneto-plasmonic nanoparticles for photothermal therapy." Doctoral thesis, Politecnico di Torino, 2020. http://hdl.handle.net/11583/2858359.

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12

Strandberg, Östman Felicia. "Optical Properties of Plasmonic Ag/Ni Square Nanostructures." Thesis, Uppsala universitet, Materialfysik, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-256885.

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13

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

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The aim of the present work is the study and the nanofabrication of innovative plasmonic nanostructured materials to develop label-free optical biosensors. The motivation arises from the need to identify specific biological molecules at very low concentrations (below the picoMolar level) and with high specificity. This goal is of paramount importance for instance in diagnostics and prognostics through the early-stage detection of markers in biological fluids indicating possible altered biological processes. At the same time a fast and simple detection scheme is required, without the use of labelling strategies. The innovative plasmonic properties of noble metals (Au,Ag) nanomaterials have been investigated for biosensing applications since 1983. These plasmonic properties arise from the interaction of an electromagnetic wave with nanostructured metals, i.e., metallic structures with size in the order of or smaller than the incident field wavelength in the Vis-NIR range: their most celebrated effect is the onset of the surface plasmon resonances (SPR). Prims-coupled biosensing devices based on SPR of gold thin film (thickness lower than 100 nm) were commercialized since 1990. These systems allow to monitor biomolecular interactions and to quantify a wide range of chemical and biological species down to nanomolar concentrations. The scientific community is strongly active in the optimization of the performances of the SPR sensors in terms of sensitivity, specificity and limit of detection. The present work is based on the application of the SPR properties of ordered Au/Ag nanoarrays for biological detection, in order to investigate and optimize their sensing performances. The detection mechanism is based on the variation of the SPR for refractive index changes, which are due to analyte molecules immobilized on the nanoarray's surface. We have studied three classes of nanoarrays based on noble metals: (i) semi-nanoshell array, (ii) nanoprism array and (iii) nanohole array. Gold and silver are the best plasmonic metals for their intrinsic properties of interaction with an electromagnetic field in the Vis-NIR range. The nanoarrays were synthesized by Nanosphere Lithography, and they are based on hexagonal arrays of nanounits such as nanoprims, semi-nanoshells and nanoholes. The synthesis technique allows to finely control the morphology and the dimensions of the nanounits and, as a consequence, their optical properties. The samples based on nanoprims and semi-nanoshells support high electromagnetic field localization on their surface, which is due to the excitation of localized SPR; for this reason these systems could be very interesting sensors to detect thin analyte molecules layers with low molecular weight. The samples based on nanoholes arrays are characterized by the EOT, which is controlled by the excitation of extended SPR. The longer decay length of this kind of plasmons makes EOT particularly useful to detect also bigger molecules such as viruses or bacteria. All the samples were functionalized with the same protocol based on the biotin-streptavidin couple as the receptor-ligand scheme. The sensing performances were investigated by exposing the functionalized samples to different analyte concentrations. Moreover, the local and bulk sensitivity to refractive index changes was measured. The experimental results were also compared with numerical simulations and we found a good level of agreement between the experimental and simulated data. Silver nanoprisms arrays were also studied as SERS substrates. They were oxidized with different treatments to investigate the silver oxide effect on the SERS performances. All the obtained results in the present work indicate performances of the three investigated nanotructures, which are at the state-of-the-art with respect to literature data.
Il tema centrale del presente lavoro di dottorato è lo studio e la nanofabbricazione di materiali plasmonici inovativi nanostrutturati per lo sviluppo di biosensori ottici label-free. La motivazione risiede nell'esigenza di identificare determinate specie biologiche in concentrazioni sempre minori (inferiore al picomolare) e con una tecnologia di rilevazione altamente sensibile e specifica, al fine di rilevare la presenza di processi biologici normali o alterati. Nello stesso tempo si richiede una rilevazione veloce, semplice e che non necessiti di un marcatore ottico. Le innovative proprietà plasmoniche che caratterizzano i nanomateriali costituiti da metalli nobili (Au,Ag) sono state investigate per applicazioni biosensoristiche fin dal 1983. Queste proprietà plasmoniche derivano dall'interazione di una radiazione elettromagnetica con i metalli nanostrutturati; i.e. strutture metalliche con dimensioni dell'ordine o minore della lunghezza d'onda della radiazione incidente nel range del Vis-NIR, e si basano sulla risonanza plasmonica superficiale (SPR). Dispositivi biosensoristici basati sulla SPR di film sottili di oro (spessore inferiore a 100 nm) accoppiati con un prisma, sono in commercio dal 1990. Questi sistemi permettono di monitorare interazioni biomolecolari e di quantificare una vasta gamma di specie chimiche e biologiche, fino a concentrazioni dell'ordine del nanomolare. La comunità scientifica è fortemente attiva nel cercare di ottimizzare le prestazioni dei sensori SPR in termini di sensibilità, specificità e limite di rilevazione. Il presente lavoro si basa sull'applicazione delle proprietà SPR di nanoarray ordinati a base di Au e Ag per la rilevazione di molecole biologiche, al fine di investigarne ed ottimizzarne le prestazioni. Il meccanismo di sensing si basa sulla variazione della SPR per variazioni di indice di rifrazione, che sono dovuti all'immobilizazione di molecole analita sulla superficie dei nanoarray. Sono state studiate tre classi di nanoarray costituiti da metalli nobili: (i) semi-nanoshell array, (ii) nanoprism array and (iii) nanohole array. Oro ed Argento sono i migliori candidati per applicazioni nel campo della plasmonica per le loro proprietà intrinseche di interazione con la radiazione elettromagnetica, in particolare nelle frequenze del visibile e del vicino infrarosso. I nanoarray sono stati sintetizzati mediante la tecnica di Litografia a Nanosfere, e sono costituiti da array esagonali di nanounità, cresciute in forma di nanoprismi, semi-nanoshells e nanoholes. La tecnica di sintesi utilizzata permette di controllare finemente la morfologia e le dimensioni delle nanounità e, di conseguenza, le rispettive proprietà ottiche. I sistemi costituiti da nanoprismi o semi-nanoshells sono caratterizzati da un'elevata amplificazione di campo elettromagnetico sulla loro superficie, la quale è dovuta all'eccitazione della SPR; per questo motivo questi sistemi potrebbero essere molto interessanti per la rilevazione di spessori molto piccoli di molecole analita con un basso peso molecolare. I nanoholes arrays sono caratterizzati dalla Trasmissione Ottica Straordinaria (EOT), che può invece essere investigata per la rilevazione di molecole di grande dimensione come virus o batteri. Tutti i campioni sono stati funzionalizzati con con lo stesso protocollo di funzionalizazione basato su una coppia modello di molecole biologiche recettore-analita (biotina-streptavidina). Le proprietà di sensing sono state investigate esponendo i campioni funzionalizzati con uno specifico recettore, a differenti concentrazioni della molecola analita. Inoltre è stata misurata la sensibilità locale e bulk in risposta alle variazioni di indice di rifrazione. I risultati sperimentali sono stati anche confrontati con dei modelli teorici ottenendo un buon accordo tra il dato sperimentale e quello simulato. I nanoprismi di argento sono stati anche studiati come possibili substrati per la spettroscopia SERS. I campioni sono stati ossidati con diversi trattamenti al fine di analizzare l'effetto dell'ossido sul segnale SERS. I risultati ottenuti nel prente lavoro hanno mostrato come le tre tipologie di nanostrutture studiate mostrino performance che sono allo stato dell'arte rispetto ai valori di letteratura.
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14

Kitenge, Denis. "Optical detection of CO and H2 based on surface plasmon resonance with Ag-YSZ, Au and Ag-Cu nanoparticle films." Scholar Commons, 2009. http://scholarcommons.usf.edu/etd/2047.

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Silver, gold, and copper metallic nanoparticle films have been utilized in various MEMS devices due to not only their electrical but also their optical properties. The focus of this research is to study the detection at room temperature of carbon monoxide (CO) and hydrogen (H2) via Surface Plasmon Resonance (SPR) phenomenon of silver-embedded Yttrium Stabilized Zirconium (Ag-YSZ) nanocomposite film, gold (Au) nanoparticle film, and an alloy film of silver-copper (Ag-Cu) , grown by the Pulsed Laser Deposition (PLD). To determine the appropriate film materials for quick and accurate CO and H2 detection at room temperature with the PLD technique, the growth process was done repeatedly. Optical tools such as X-Ray Diffraction, Alpha Step 200 Profilometer, Atomic Force Microscopy, and Scanning Electron Microscopy were used to characterize thin films. The gas sensing performance was studied by monitoring the SPR band peak behavior via UV/vis spectrophotometer when the films were exposed to CO and H2 and estimating the percent change in wavelength. The metallic nanoparticle films were tested for concentration of CO (100 to 1000 ppm) and H2 (1 to 10%). Silver based sensors were tested for the cross-selectivity of the gases. Overall the sensors have a detection limit of 100 ppm for CO and show a noticeable signal for H2 in the concentration range as low as 1%. The metallic films show stable sensing over a one-hour period at room temperature. The SPR change by UV/vis spectrophotometer shows a significant shift of 623 nm wavelength between 100 ppm CO gas and dry air at room temperature for the alloy films of Ag-Cu with a wider curve as compared to silver and gold films upon their exposure to CO and H2 indicating an improvement in accuracy and quick response. The results indicate that in research of CO and H2 detection at room temperature, optical gas sensors rather than metal oxide sensors are believed to be effective due to not only the absence of chemical involvement in the process but also the sensitivity improvement and accuracy, much needed characteristics of sensors when dealing with such hazardous gases.
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15

Kitenge, Denis. "Optical detection of CO and H₂ based on surface plasmon resonance with Ag-YSZ, Au and Ag-Cu nanoparticle films." [Tampa, Fla] : University of South Florida, 2009. http://purl.fcla.edu/usf/dc/et/SFE0003296.

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16

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

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Plasmonic nanoparticles show potential for numerous different biomedical applications, including diagnostic applications such as targeted labelling and therapeutic applications such as drug delivery and therapeutic hyperthermia. In order to support the development of these applications, imaging techniques are required for imaging and characterising nanoparticles both in isolation and in the cellular environment. The work presented in this thesis relates to the use and development of two different optical techniques for imaging and measuring the localised surface plasmon resonance of plasmonic nanoparticles, both for isolated particles and for particles in a cellular environment. The two techniques that have been used in this project are hyperspectral darkfield microscopy and spatial modulation microscopy. Hyperspectral darkfield microscopy is a darkfield technique in which a supercontinuum light source and an acousto-optic tuneable filter are used to collect darkfield images which include spectral information. This technique has been used to measure the spectra of single nanoparticles of different shapes and sizes, and nanoparticle clusters. The results of some of these measurements have also been correlated with finite element method simulations and transmission electron microscope images. The hyperspectral darkfield technique has also been used to image cells that have been incubated with nanoparticles, demonstrating that this technique may also be used to measure the spectra of nanoparticle clusters on a cellular background. Spatial modulation microscopy is based on fast modulation of the position of a nanoparticle in the focus of an optical beam. This modulation results in a variation in transmitted intensity, which can be detected with very high sensitivity using a lock-in amplifier. Since, for biological imaging applications it is desirable to be able to image, for example whole cells in real time, a fast scanning version of this technique has been implemented, which increases the applicability of the technique to imaging of nanoparticles in cells
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17

Otomalo, Tadele. "Ultrafast optical response of complex plasmonic nanoparticles." Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLC102.

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Les propriétés remarquables associées à la résonance plasmon localisée (LSPR) dans les nanoparticules (NP) de métaux nobles font de la plasmonique un sujet aux applications multiples. Lorsque les NP sont éclairées par des impulsions laser ultracourtes, une dynamique rapide d'échanges d'énergie conduit à la variation ultrarapide de leurs propriétés optiques, accompagnée d’autres effets comme la photoluminescence, l’échauffement hyperlocalisé, la photoémission électronique, la production de radicaux libres, la nano-cavitation. La conception de nanostructures hybrides complexes permet d'adapter les propriétés plasmoniques pour optimiser les applications. Nous avons étudié certaines nanostructures hybrides par spectroscopie d'absorption pompe-sonde large bande et une modélisation dédiée : fibres de silice décorées de NP d’or, NP cœurs-coquilles Au-Ag. Leurs réponses optiques stationnaire et transitoire sont analysées en fonction de la morphologie des NP.Dans les développements évoqués ci-dessus, l’exaltation de champ proche autour des NP plasmoniques joue un rôle clé. Cependant, l’étude de la modulation transitoire du champ proche est limitée par l'incapacité des outils numériques usuels à saisir de faibles variations de la permittivité des NP. Nous mettons en œuvre une méthode FDTD basée sur les paires pole-résidu complexes-conjugués pour pouvoir simuler l’évolution temporelle de la topographie du champ proche plasmonique. Au-delà, le mode LSPR peut être couplé à un mode photonique dans une cavité hybride pour concevoir des fonctionnalités photoniques optiquement contrôlées. Le couplage d'un réseau 2D de nanobâtonnets d'or parallèles avec le mode de défaut d'une cavité d’un cristal photonique 1D est étudié théoriquement. L'anisotropie optique permet de jouer avec plusieurs degrés de liberté comme la polarisation du champ. La modulation ultrarapide de la réponse optique prédite dans de telles nanostructures hybrides ouvre la possibilité de leur optimisation future pour la conception de capteurs résolus en temps
The remarkable properties associated with the localized plasmon resonance (LSPR) in noble metal nanoparticles (NPs) make plasmonics an important topic with multiple applications. When NPs are illuminated by ultrashort laser pulses they undergo a rapid dynamics of energy exchanges which leads to the ultrafast variation of their optical properties, associated with other effects such as broadband photoluminescence, hyperlocalized heat release, electron photoemission, production of reactive oxygen species and nano-cavitation. The design of complex hybrid nanostructures can enable us to tailor the plasmonic properties as to optimize the applications. We have studied some hybrid nanostructures by broadband pump-probe absorption spectroscopy and a dedicated modeling: AuNP-decorated silica fibers and core-shell Au-Ag NPs. Their stationary and transient optical responses are analyzed depending on the NP morphology.In the developments evoked above the enhanced near field around plasmonic NPs plays a key role. However, the study of the ultrafast transient modulation of the near field is limited by the inability of the conventional numerical tools to catch the small variations of the NP permittivity. Here, a complex-conjugate pole-residue pair based FDTD method is successfully implemented to simulate the time-dependence of the plasmonic near-field topography. Beyond, the LSPR mode can be resonantly coupled with a photonic mode in a hybrid microcavity for conceiving optically-controlled photonic functionalities. The coupling of a 2D array of parallel gold nanorods with the defect mode of a 1D photonic crystal cavity is investigated theoretically. The optical anisotropy enables us to play with several degrees of freedom like field polarization. The ultrafast modulation of the optical response that is predicted in such hybrid nanostructures opens the possibility of their future optimization for designing time-resolved sensors
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18

Cheng, Ka Ying. "Nano-metals plasmonic coupling." HKBU Institutional Repository, 2020. https://repository.hkbu.edu.hk/etd_oa/747.

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In this work, we investigated nano-metal plasmonic coupling between dissimilar metals. We measured the optical transmission of nano-Ag coupled to other nano-metals using glass and Si substrates respectively. The reflected colors shifted from yellow to violet were obtained through the plasmonic coupling with nearest-neighbor nano-metals such as aluminum, magnesium, and ytterbium nano-metals. They were deposited randomly next to the nano-Ag. The metal size is from 8 to 15 nanometers. The results show that the colors changing is essentially due to plasmonic coupling between nano-Ag and another the nano-metals e.g. nano-Al The coupling caused a red shift in plasmonic resonance frequency, thus, changing the reflection color. The resonance shift agrees well with the simulation result using COMSOL. The inter-particle distance and particle size dependency of the optical spectra correspond to surface plasmon resonance extinction peaks for isolated nano-Ag and coupled with those neighboring nano- metals. Due to plasmonic coupling between nanoparticles in small space can create new resonances; red shifts as the interparticle distance reduce. Wavelengths are tuned by the extent of the interparticles interactions which relate to the particles size, interparticles distance and the similarity of nano metals. Using different nano metals to fabricate thin films can change the plasmonic resonance frequency which makes the reflected colours become multihued. When we look into the effect of the nano-particle size, and the distance between nano-particles, we discovered that larger nano-particle size has larger distance between the particles, and since the plasmonic coupling is a function of Inverse Square of the distance between particles. Therefore, smaller nano-particles have the strongest plasmonic coupling. Al produced the smallest nano-particle therefore it has the shortest distance between nano-Al and nano-Ag. Since the size of the particles can be controlled during deposition, the color changing of nano-Ag can be well defined. Thus tunable color changing devices can be fabricated
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19

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

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20

Dienerowitz, Maria. "Plasmonic effects upon optical trapping of metal nanoparticles." Thesis, University of St Andrews, 2010. http://hdl.handle.net/10023/1634.

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Optical trapping of metal nanoparticles investigates phenomena at the interface of plasmonics and optical micromanipulation. This thesis combines ideas of optical properties of metals originating from solid state physics with force mechanism resulting from optical trapping. We explore the influence of the particle plasmon resonance of gold and silver nanospheres on their trapping properties. We aspire to predict the force mechanisms of resonant metal particles with sizes in the Mie regime, beyond the Rayleigh limit. Optical trapping of metal nanoparticles is still considered difficult, yet it provides an excellent tool to investigate their plasmonic properties away from any interface and offers opportunities to investigate interaction processes between light and nanoparticles. Due to their intrinsic plasmon resonance, metal nanoparticles show intriguing optical responses upon interaction with laser light. These differ greatly from the well-known bulk properties of the same material. A given metal nanoparticle may either be attracted or repelled by laser light, only depending on the wavelength of the latter. The optical forces acting on the particle depend directly on its polarisability and scattering cross section. These parameters vary drastically around the plasmon resonance and thus not only change the magnitude but also the direction and entire nature of the acting forces. We distinguish between red-detuned and blue-detuned trapping, that is using a trapping wavelength shorter or longer than the plasmon resonance of the particle. So far optical trapping of metal nanoparticles has focussed on a wavelength regime far from the particle’s resonance in the infrared. We experiment with laser wavelengths close to the plasmon resonance and expand the knowledge of metal nanoparticle trapping available to date. Existing theoretical models are put to the test when we compare these with our real experimental situations.
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21

Zhang, Li. "FDTD Algorithm for Plasmonic Nanoparticles with Spatial Dispersion." The Ohio State University, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=osu1452174003.

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22

Rouxel, Romain. "Ultrafast thermo-optical dynamics of single plasmonic nanoparticles." Thesis, Lyon, 2020. http://www.theses.fr/2020LYSE1306.

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Les changements de propriétés dynamiques de nanodisques d'or individuels supportés sur un substrat de saphir ont été étudiés sur des échelles de temps allant de la femtoseconde à la nanoseconde par la combinaison des techniques de spectroscopie par modulation spatiale et de spectroscopie optique résolue en temps. Les nanodisques sont mis hors-équilibre par l’absorption d’une impulsion optique de pompe, et leur relaxation est sondée optiquement par la mesure de la transmission d’une seconde impulsion. Dans la première partie de ce travail, la dynamique du transfert de chaleur du nano-objet au substrat a été mesurée de manière systématique pour des nanodisques de différentes dimensions. Les refroidissements observés sont quasi-exponentiels, avec une constante de temps dépendant principalement de l'épaisseur du disque, et faiblement de son diamètre. La comparaison des signaux expérimentaux avec les résultats de calculs par éléments finis indique que la dynamique de refroidissement est principalement limitée par la résistance thermique de Kapitza à l'interface nanodisque-substrat, dont la valeur a pu être extraite. En outre, la sensibilité des mesures pompe-sonde aux changements de température du nano-objet a été déterminée expérimentalement en fonction de la longueur d'onde de la sonde, ses valeurs et variations spectrales présentant un bon accord quantitatif avec les résultats d'un modèle thermo-optique par éléments finis. La deuxième partie de cette thèse se concentre sur les phénomènes ultra-rapides consécutifs à la photo-excitation d’un nano-objet, qui conduisent à sa thermalisation interne par des échanges d’énergie électron-électron et électron-phonon. En particulier, la sensibilité à ces phénomènes de l’extinction optique de nanodisques individuels a été étudiée expérimentalement en fonction de la longueur d'onde de la sonde. Ces mesures ont été comparées aux résultats d'un modèle numérique complet basé notamment sur la résolution de l'équation de Boltzmann et prenant également en compte l'effet du chauffage du réseau ionique, conduisant à un bon accord quantitatif. Une version simplifiée de ce modèle a également permis de mettre en évidence les rôles respectifs de l’évolution des températures des électrons et du réseau, clarifiant ainsi grandement les dépendances temporelle et spectrale des signaux résolus en temps
The ultrafast dynamics of individual gold nanodisks supported on a sapphire substrate occurring at femtosecond to nanosecond timescales have been investigated using the combination of single-particle spatial modulation and time-resolved optical spectroscopies. Nanodisks are excited out of equilibrium by the absorption of an optical pump pulse, and their relaxation is optically probed by measuring the transmission of a second probe pulse. In the first part of this work, the dynamics of heat transfer from the nano-object to the substrate have been systematically measured for nanodisks of various dimensions. Quasi-exponential cooling kinetics were found, with a time constant mainly depending on the disk thickness and weakly on its diameter. Comparison of experimental signals with the results of finite-element calculations indicates that the cooling dynamics are primarily limited by the Kapitza thermal boundary resistance at the nanodisk-substrate interface, whose value could be extracted. Additionally, the sensitivity of pump-probe measurements to transient temperature changes in the nano-object was experimentally determined as a function of the probe wavelength, its values and spectral variations presenting a good quantitative agreement with the results of a thermo-optical finite-element model. The second part of this thesis focuses on the ultrafast phenomena immediately following the nano-object photo-excitation, leading to its internal thermalization through electron-electron and electron-phonon energy exchanges. In particular, the sensitivity of the optical extinction of individual nanodisks to these phenomena has been experimentally investigated as a function of the probe wavelength. These measurements were compared with the results of a complete numerical model based notably on the resolution of the Boltzmann equation and also taking into account the effect of lattice heating, yielding a good quantitative agreement. A simplified version of this model also allowed to highlight the respective roles of the temperature evolutions of the electrons and of the ionic lattice, greatly clarifying the temporal and spectral dependences of the measured time-resolved signals
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23

Abkhalimov, E. V., R. D. Solovov, and B. G. Ershov. "Composite Ag-Pt Nanoparticles in Aqueous Solution." Thesis, Sumy State University, 2012. http://essuir.sumdu.edu.ua/handle/123456789/35033.

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It is shown that the saturation of an aqueous solution containing K2PtCl4 with hydrogen in the presence of 6.3 nm silver nanoparticles leads to the reduction of platinum on the silver surface and the formation of Ag/Pt core-shell nanoparticles. The Ag:Pt molar ratio is varied from 9:1 to 1:9 for synthesizing Pt shell layer of different thickness. An apparent shift of Ag surface plasmon band from 405 nm to 230 nm and broadening of one with decrease of Ag:Pt ratio was observed. The TEM images and SAED pattern of Pt@Ag nanoparticles has been obtained. The UV-Vis and TEM data confirms a formation of Ag/Pt coreshell nanoparticles. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/35033
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24

Auer, Mathias. "Preferentially Orienting Ag Nanoparticles Using CaF2 Nanorods." VCU Scholars Compass, 2012. http://scholarscompass.vcu.edu/etd/2730.

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A study was done to examine the effect of surface orientation as well as heterogeneous epitaxy at an interface between two materials with a large lattice mismatch. Silver nanoparticles of different diameters were grown in an effort to study methods of preferentially orienting the geometry of metal nanoparticles. Arrays of calcium fluoride nanorods were grown on silicon substrates using oblique angle thermal vapor deposition. The chamber operated at an ultra high vacuum pressure of 10^-10 Torr during the deposition of the rods and an oblique angle of 75° was kept between the silicon substrate normal and the direction of incident flux. A method was then developed to grow silver nanoparticles exclusively on the (111) facet of the calcium fluoride tips. This was accomplished by once again using oblique angle deposition with an angle of 75° along with the larger size of the (111) calcium fluoride tip facet. Cross sectional scanning electron microscopy and transmission electron microscopy imaging was used to verify that the nanoparticles adhered exclusively to the desired facet of the tip. Using selected area diffraction, (SAED) and dark field in the TEM, it was shown that the nanoparticles did grow at a (111) orientation at the interface between them and the calcium fluoride rods. Different thicknesses and diameters of nanoparticles were then grown to determine what an ideal size was to achieve the most (111) orientation of the nanoparticles. Thicknesses of the particles varied between 5 nanometers and 15 nanometers. Through characterization it was shown that all three of the different thicknesses grown exhibited (111) orientation of the silver nanoparticles, both at the interface and in the overall nanoparticle as well with the 10 nanometer sample being the most ideal in terms of the desired result. Lattice straining of the silver nanoparticles was also observed by characterization through diffraction and SAED.
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25

Dahal, Naween. "Synthesis and characterizations of novel magnetic and plasmonic nanoparticles." Diss., Manhattan, Kan. : Kansas State University, 2010. http://hdl.handle.net/2097/4269.

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26

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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27

Beliatis, Michail. "Laser fabrication of plasmonic metal nanoparticles for optoelectronic devices." Thesis, University of Surrey, 2011. http://epubs.surrey.ac.uk/761383/.

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Metal nanoparticles (MNP) are widely researched for the fabrication of novel low cost and more energy efficient optoelectronic devices. MNPs, which exhibit surface plasmon resonance (SPR), can be incorporated into thin film photovoltaic structures and as well as into substrates for enhancing the Raman spectroscopy performance. Recent demonstration of devices with plasmonic structures has limited utility due to the need for techniques of ordered MNPs for large area fabrication that are not currently available. This work examines the suitability of laser annealing for the fabrication of metal nanoparticles in large area optoelectronic devices, as well as the potential for tuning their optical properties precisely within the structure. Gold (Au), silver (Ag) and AuAg alloy particles were fabricated with laser annealing and fully characterized. Morphology characterization of the metal nanopartlcle films (MNFs) with scanning electron microscopy (SEM) and atomic force microscopy (AFM) revealed the control over the size by adjusting initial film thickness· and laser fluence. Optical characterization with UV-VIS spectrometry demonstrated that SPR of MNFs can be tuned by adjusting the alloy composition, the dielectric constant of surrounding medium, and the size distribution. This experimental result was confirmed by simulations. Direct incorporation of large well distributed Au nanoparticles into solar cells demonstrated enhanced performance. Dense MNFs with small particles decreased the photovoltaic efficiency. By contrast, in the case of Raman, small alloy particles with SPR wavelength close to the pump wavelength demonstrated the best enhancement. High resolution metal nanoparticle tracks written by the laser demonstrated gas sensing with good sensory capability. However, their high resistivity imposes difficulties in measurements. We conclude that with suitable optimisations the laser annealing technique studied here could be utilised for the fabrication of metal nanoparticles in large area optoelectronics devices. We demonstrate a number of such applications including solar cells and gas sensors and study the effects of metal nanoparticles within these devices in this thesis.
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Zhang, Xingguang. "Plasmonic photocatalysts of supported gold nanoparticles for organic conversions." Thesis, Queensland University of Technology, 2014. https://eprints.qut.edu.au/67714/4/Xingguang_Zhang_Thesis.pdf.

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This thesis is a comprehensive study of plasmonic gold photocatalysts for organic conversions. It presents the advantages of plasmonic gold photocatalysts in the selective oxidation, reduction, and acetalisation. It is discovered that plasmonic gold photocatalysts exhibit better catalytic performance (higher selectivity or activity) in these organic conversions. The study in this thesis highlights the capacity of plasmonic gold photocatalysts in harvesting solar energy for converting organic raw materials to value-added chemicals, and the great potential of gold photocatalysts in chemical production.
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29

Yen, Chun-Wan. "Plasmonic photochemistry on the nanoscale." Diss., Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/41085.

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When nanoparticles are small in size compared to the wavelength of incident light, a localized surface plasmon resonance occurs. For certain noble metals, such as gold and silver, this frequency occurs in the visible or near IR range, and therefore it can be utilized for many important applications. Only silver and gold nanoparticles were utilized in this thesis work, and they were used in application for three separate files: environment, catalysis, and energy.
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Rafiei, Miandashti Ali. "Synthesis, Characterization, and Photothermal Study of Plasmonic Nanostructures using Luminescence Nanomaterials." Ohio University / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1553788360252461.

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31

Dias, Jorge Maião Peres Teixeira. "Noble metal nanoparticles - Au and Ag - for biodetection." Master's thesis, Faculdade de Ciências e Tecnologia, 2008. http://hdl.handle.net/10362/3935.

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Dissertation submitted for obtainment of the Master’s Degree in Biotechnology, by the Universidade Nova de Lisboa, Faculdade de Ciências e Tecnologia
Metal nanoparticles possess unique optical, chemical and magnetic properties due to their size, shape and composition. Taking advantage of these properties, new biosensors have been developed using, mainly, gold nanoparticles. Silver nanoparticles, due to its enhanced surface plasmon resonance extinction coefficient are alternate candidates as labels to biodetection. However, unlike gold nanoparticles, silver nanoparticle derivatization with thiol-modified oligonucleotides requires cumbersome and time-consuming protocols. To circumvent this limitation, an approach is the use of gold-silver alloy nanoparticles, taking advantage of the ease of derivatization of gold nanoparticles and the enhanced surface plasmon resonance extinction coefficient of silver nanoparticles. This work describes the synthesis and characterization of gold-silver alloy nanoparticles (50% gold, 50% silver) and their thiol-ssDNA functionalized counterparts (nanoprobes) for application in molecular diagnostics. These new nanoprobes were used to specifically detect a sequence derived from the RNA polymerase -subunit gene of Mycobacterium tuberculosis, the etiologic agent of human tuberculosis. Complementary targets were detected using a non-cross-linking assay that consists on the spectrophotometric comparison between solutions before and after salt-induced nanoprobe aggregation. This new approach should allow the use of gold-silver alloy nanoparticles with different gold molar fractions, or even bimetallic nanoparticles composed of other metals (e.g., Cu, Pt) in the development of biosensors. The conjugation of these new nanoprobes with the well-established gold nanoparticle system can be the basis of new multiplex methods for specific DNA, RNA and/or other molecules biodetection.
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Burrows, Christopher P. "Plasmonic resonances of metallic nanoparticles in arrays and in isolation." Thesis, University of Exeter, 2010. http://hdl.handle.net/10036/3069.

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Plasmonics is the branch of photonics that is concerned with the interactions which take place between metallic structures and incident electromagnetic radiation. It is a field which has seen a recent resurgence of interest, predominantly due to the emerging fields of metamaterials and sub-wavelength optics. The original work contained within this thesis is concerned with the plasmonic resonances of metallic nanoparticles which can be excited with visible light. These structures have been placed in a variety of configurations, and the optical response of each of these configurations has been probed both experimentally, and with numerical simulations. The first chapter contains some background and describes some recent advances in the literature, set against the broad background of more general concepts which are important in plasmonics. The best starting point in describing the response of plasmonic systems is to consider individual metallic particles and this is the subject of the second chapter. Three separate modelling techniques are described and compared, and dark-field spectroscopy is used to produce experimental scattering spectra of single particles which support dipolar and higher order modes. Mie theory is used as a starting point in understanding these modes, and finite element method (FEM) modelling is used to make numerical comparisons with dark-field data. When two plasmonic particles are placed close to each other, interactions take place between them and their response is modified, sometimes considerably. This effect can be even stronger if particles are placed in large arrays. Interactions between the dipolar modes of gold particles form the basis of the third chapter. The discussion begins with pairs of particles, and the coupled dipole approximation (CDA) is introduced to describe the response. Ordered square arrays are considered and different modelling techniques are compared to experimental data. Also, random arrays have been investigated with a view to inferring the extinction spectrum of a single particle from a carefully chosen array of particles in which the inter-particle interactions are suppressed. The fourth chapter continues the theme of particles interacting in arrays, but the particles considered support quadrupolar modes (and they are silver instead of gold). The optical response is strongly modified, and an explanation is provided which overturns the accepted explanation. The final chapter of new results is somewhat different to the others in that a very different structure is considered and different parameters are extracted. Instead of far-field quantities, here, near-fields of composite structures are of interest; they can generate greatly enhanced fields in the vicinity of the structure. These enhanced fields, in turn, enhance the fluorescence and Raman emission of nearby dye molecules. A novel field integration technique is proposed which aims to mimic the experiments which were carried out using fluorescence confocal microscopy.
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33

Damato, Ralph. "Polarization control of plasmonic modes in single nanoparticles and nanostructures." Thesis, California State University, Long Beach, 2014. http://pqdtopen.proquest.com/#viewpdf?dispub=1527542.

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This thesis investigates the fundamental nanoscale near-field light matter interaction between a probe tip and plasmonic antenna nanostructures. The thesis is focused on polarization control of metallic plasmon modes using scattering-type scanning near-field optical microscopy (s-SNOM). Part of the thesis is dedicated to spectroscopic near-field comparison of coated and bare single plasmonic particles in the infrared wavelength range (λ= 9–11 µm) using s-SNOM. By tuning the wavelength of the incident light, we have acquired information on the spectral polarization dependence plasmon modes and plasmon/phonon–polariton resonant near-field interactions. The enhanced near-field coupling between the probe tip and high index Au nanostructures and Au-core thin silica coating (thickness ≈10 nm) is described and quantified.

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34

Austin, Lauren Anne. "Exploring some aspects of cancer cell biology with plasmonic nanoparticles." Diss., Georgia Institute of Technology, 2014. http://hdl.handle.net/1853/54236.

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Plasmonic nanoparticles, specifically gold and silver nanoparticles, exhibit unique optical, physical, and chemical properties that are exploited in many biomedical applications. Due to their nanometer size, facile surface functionalization and enhanced optical performance, gold and silver nanoparticles can be used to investigate cellular biology. The work herein highlights a new methodology that has exploited these remarkable properties in order to probe various aspect of cancer cell biology, such as cell cycle progression, drug delivery, and cell death. Cell death mechanisms due to localized gold and silver nanoparticle exposure were also elucidated in this work. Chapter 1 introduces the reader to the synthesis and functionalization of gold and silver nanoparticles as well as reviews their implementation in biodiagnostic and therapeutic applications to provide a foundation for Chapters 3 and 4, where their use in spectroscopic and cytotoxic studies are presented. Chapter 2 provides the reader with detailed explanations of experimental protocols for nanoparticle synthesis and functionalization, in vitro cellular biology experiments, and live-cell Raman spectroscopy experiments that were utilized throughout Chapters 3 and 4. Chapter 3 presents the use of nuclear-targeted gold nanoparticles in conjunction with a Raman microscope modified to contain a live-cell imaging chamber to probe cancer cell cycle progression (Chapter 3.1), examine drug efficacy (Chapter 3.2), monitor drug delivery (Chapter 3.3), and detect apoptotic molecular events in real-time (Chapter 3.4). In Chapter 4, the intracellular effects of gold and silver nanoparticles are explored through live-cell Rayleigh imaging, cell cycle analysis and DNA damage (Chapter 4.1), as well as through the elucidation of cytotoxic cell death mechanisms after nanoparticle exposure (Chapter 4.2) and live cell imaging of silver nanoparticle treated cancer cell communities (Chapter 4.3).
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Rondon, B. Rebeca A. "Gold Nanoparticles Plasmonic Enhancement for Decoding Of Molecule-Surface Interactions." Thesis, Université d'Ottawa / University of Ottawa, 2018. http://hdl.handle.net/10393/37950.

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In this research, the use of gold nanostructures (AuNS) was explored to evaluate the interaction between molecules and the nanoparticle (NP) surface. In that way, three different projects were developed; one project using fluorescence and two projects using Raman spectroscopy as measuring technique. The fluorescence spectroscopy project used the fluorescence lifetime imaging microscope (FLIM) to evaluate the relative position of the molecules methylene blue (MB) and cucurbit[7]uril (CB) on the gold nanoparticle (AuNP) surface. Although the inclusion complex is favored in solution, it was found that MB forms an exclusion complex with CB, when CB is attached to the AuNP surface. The first project utilizing Raman spectroscopy, specifically surface enhanced Raman scattering (SERS), took advantage of a confined system (a reverse micelle) to evaluate the Raman signal of water molecules in close proximity to the AuNP surface. It was observed that the SERS water signal had a big shift to higher energies compared with the Raman signal of the bulk water; indicating the water molecules in the system are subjected to different bond-stretching energies. The second Raman project studied the modification of two different AuNS (specifically AuNP and gold nanorod -AuNR) with thiols. Different thiols were used to evaluate the kinetics of the modification of the AuNS surface, also the different AuNS presented different ligands on their surface. In general, and considering the difference in the bonding strength of the ligands present on the AuNS surface (by synthesis) and the size of the thiol, at least 2 h are required to modify the complete AuNS surface.
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Zhang, Lu. "Design of plasmonic nanoparticles and their use for biotoxin immunosensing." Electronic Thesis or Diss., Sorbonne université, 2018. https://accesdistant.sorbonne-universite.fr/login?url=https://theses-intra.sorbonne-universite.fr/2018SORUS439.pdf.

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L'entérotoxine A du staphylocoque (SEA) produite par certaines souches de Staphylococcus aureus est une cause majeure d'intoxication alimentaire et représente la deuxième cause de maladies d'origine alimentaire en France. Les nanoparticules (NPs) plasmoniques aux propriétés optiques uniques sont largement utilisées comme transducteurs dans les biocapteurs en raison du phénomène de résonance de plasmons de surface localisée (LSPR). L'objectif de ce travail était de développer des biocapteurs basés sur des NPs plasmoniques à partir desquels la détection de SEA pourrait être réalisée par lecture à l'œil nu. Deux stratégies ont été mises en place. La première stratégie reposait sur le coefficient d'extinction extrêmement élevé des AuNPs. Des AuNPs conjuguées à l’anticorps anti-SEA (Ab) ont été utilisées comme rapporteurs dans l’immunocapteur colorimétrique en phase solide de type sandwich. Le capteur a été appliqué avec succès à la détection de SEA dans le tampon et le lait. 1 ng de SEA pourrait être visualisée par lecture à l’œil nu. La deuxième stratégie reposait sur la sensibilité de la bande LSPR de NPs plasmoniques au faible changement d'indice de réfraction local et à la capacité de l'homme à visualiser les changements de couleur dans la région de 500 nm. À cette fin, des NPs cœur-coquille or-argent (Au@AgNPs) avec la bande à 500 nm ont été synthétisées. La conjugaison de l'Ab aux Au@AgNPs a entraîné un décalage vers le rouge de la bande LPSR et un changement de couleur visuel de l'orange au rouge. Cependant, le décalage vers le rouge de la bande était important et aucun changement de couleur visible n’a été observé à l’œil nu lors de l’addition ultérieure de SEA
Staphylococcal enterotoxin A (SEA) produced by some Staphylococcus aureus strains is a major cause of food poising and especially represents the second cause of foodborne diseases in France. Plasmonic nanoparticles with unique optical properties are widely applied as transducers in biosensing devices owing to the Localized Surface Plasmon Resonance (LSPR) phenomenon. The objective of this work was to develop biosensors based on plasmonic nanoparticles from which SEA detection could be achieved by naked-eye readout. Two strategies were implemented. The first strategy was based on the extremely high extinction coefficient of gold nanoparticles (AuNPs). Anti-SEA antibody (Ab)-conjugated AuNPs were used as reporters in a solid-phase, sandwich-type, colorimetric immunosensor. The sensor was successfully applied to the detection of SEA in buffer and spiked milk. As low as 1 ng SEA could be visualized by naked-eye readout. The second strategy relied on both the sensitivity of the LSPR band of plasmonic nanoparticles to small local refractive index change and the ability of humans to visualize color changes in the 500 nm region. For this purpose, core-shell gold silver nanoparticles (Au@AgNPs) with LSPR band at 500 nm were successfully synthesized. Attachment of Ab to Au@AgNPs resulted in a red shift of LPSR band and a visual color change of colloidal solution from orange to red. Yet, the red shift of LSPR band was very important and no visible change of color was observed by naked-eye upon subsequent addition of SEA
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37

Liu, Junjun. "Optical properties of chiral plasmonic nanoparticles and mesoporous silicon nanowires." HKBU Institutional Repository, 2017. https://repository.hkbu.edu.hk/etd_oa/385.

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Structural engineering plays an essential role in controlling the optical properties of nanostructures, which are of fundamental and practical interest in nanoscience and technology. In this study, two kinds of nanostructural engineering were investigated systematically to enrich nano-optics research: structural helicity was imposed on plasmonic nanoparticles (NPs) with chiroptical activity engineerable in the ultraviolet (UV)-visible region, and porosification was imposed on silicon nanowires (SiNWs) to tune optical interaction and photoluminescence (PL).. The generation of helical metamaterials, which have strong, engineerable chiroptical activity in the UV-visible region, has attracted increasing attention due to the manipulation of the circular polarization state of light to develop diverse homochirality-associated bio-applications. Glancing-angle deposition with fast substrate rotation is performed to generate plasmonic helical NPs (PhNPs) with a helical pitch (P) of less than 10 nm, which is so much smaller than the wire diameter (d) that the PhNPs appear to be achiral NPs. The PhNPs exhibit chiroptical activity that originates intrinsically from hidden helicity, characterized by circular dichroism (CD). With an increase of P from 3 to 66 nm, the plasmonic CD signals barely shift but show a logarithmic amplification. PhNPs made of aluminum, silver, and copper exhibit a stable chiroptical response from the deep UV (~220 nm) region to the visible region. When an achiral plasmonic nanostructure guest is coated on a PhNP host (i.e., a chiral host@achiral guest nanostructure is created), the achiral guest becomes chiroptically active due to helicity transfer from the chiral host to the achiral guest. Such a helicity transfer can be generally adapted to diverse plasmonic metals to tailor the plasmonic chiroptical response flexibly in the UV-visible region. Furthermore, an amplification of the near-field optical chirality induced by the PhNPs would pave a novel way to performing asymmetric syntheses, for which investigations are currently lacking. Silver PhNPs are used to effectively mediate the enantioselective photocyclodimerization of 2-anthracenecarboxylate: left-handed silver PhNPs lead to a positive ee (enantiomeric excess) value, and right-handed silver PhNPs give rise to a negative ee value. The enantioselectivity is enhanced with a decreasing P. The PhNP-mediated enantioselective photocyclodimerization is ascribed to the synergistic contribution from chirally helical surface-induced enantioselective adsorption of 2-anthracenecarboxylate and chiroptically active nanoplasmon-enhanced optical chirality of near-field circularly polarized light.. Metal-assisted chemical etching (MACE) is carried out to generate mesoporous SiNWs (mp-SiNWs) with mesopores from 2 to 50 nm. The porosification imposes two prominent properties onto SiNWs: a high surface-to-volume ratio and quantum confinement ascribed to the shrinkage of silicon skeletons. Hence, engineering the porosity of SiNWs is of fundamental importance. Here, a new method is devised to reduce the porosity of mp-SiNWs without changes in the MACE conditions. After generating the mp-SiNWs with high porosity, the mp-SiNWs are removed from the mother Si wafers with sticky tape, followed by MACE under the same conditions to produce low-porosity mp-SiNWs. Less porous mp-SiNWs reduce optical scattering from the porous Si skeletons and vertically protrude on the wafer without aggregation to facilitate optical trapping. Consequently, low-porosity mp-SiNWs effectively reduce UV-visible reflection loss. Furthermore, optical applications require surface modification of mp-SiNWs with functional chemicals, which has a prerequisite to passivate mp-SiNWs with H-termination using 5% hydrogen fluoride. 40% NH4F, which has been widely used to passivate Si(111) wafers with H-termination, tends to unexpectedly etch mp-SiNWs attributed to surface F-termination caused by the nucleophilic attack of F− anions to Si atoms. It has been used to study systematically the NH4F-etching rate as a function of the doping levels of SiNWs, surface crystalline orientations, and porosity. At a modest temperature of 110°C, 1,4-diethynylbenzene (DEBZ) is grafted via monosilylation grafted on H-terminated mp-SiNWs. The modified mp-SiNWs with chemically active monolayers is facilely subjected to further chemical modification and surface functionalization. In addition, the monosilylation encodes mp-SiNWs with PL of DEBZ, opening a door to flexible engineering of PL of mp-SiNWs for optoelectronic and bio-detection applications.
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38

Sediq, Khalid. "The optical properties of photonic-crystal nanocavities containing plasmonic nanoparticles." Thesis, University of Sheffield, 2016. http://etheses.whiterose.ac.uk/12324/.

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39

Ott, Andreas. "Synthesis and application of hybrid materials based on plasmonic nanoparticles." Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät, 2016. http://dx.doi.org/10.18452/17511.

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Hybride Nanostrukturen verbinden die Vorzüge von individuellen Materialien, die neue Eigenschaften hervorrufen können. In dieser Arbeit wurden verschiedene Metal Nanostrukturen synthetisiert und deren optische Eigenschaften analysiert. Die Herstellung eines Spasers oder Lichteinfang in Solarzellen wurde untersucht. Der Einfluß von Größe, Form und Brechungsindex auf die Metal-Plasmonen wurde erforscht. Die gewonnen Erkenntnisse genutzt um Metal Nanopartikel mit gezielten Eigenschaften herzustellen. Hybride Gold Nanostrukturen (funktionalisiert mit Farbstoffen oder Quantenpunkten) wurden hergestellt und Energie-Transfereffekte untersucht. Diese hybriden Nanostrukturen wurden optisch gepumpt um Spasing zu erreichen. Allerdings wurde festgestellt, dass eine unrealistisch hohe Verstärkung benötigen wird, um die charakteristischen Verluste im Metal zu überwinden. Silber und Gold Nanopartikel wurden synthetisiert um diese in Dünnschichtsolarzellen einzusetzen. Es konnte gezeigt werden, dass Silber chemisch instabil ist und, wenn oxidiert, hohe Absorption auftritt. Durch hohe Temperaturen konnte die Oxidschicht auf den Silberpartikeln reduziert werden und damit auch die Verluste. Stabilere Gold Partikel wurden in Perovskit-Solarzellen eingebaut, wodurch die Effizienz einer solch modifizierten Solarzelle um ~40% gesteigert werden konnte. Dies wurde durch eine erhöhte Anzahl an generierten Ladungsträgern mittels metallischen Lichtfallen erreicht. Zusätzlich wurden anisotrope Janus Trägerpartikel synthetisiert und mit Metal Nano-partikeln funktionalisiert. Gold Nanopartikel wurden abgeschieden und zu einer Gold Hülle gewachsen. Dies erfolgte entweder gleichförmig über das gesamte Hantel-Trägerpartikel oder einseitig unter Ausnutzung der chemischen Anisotropie. Desweiteren wurden Platin Nano-partikel einseitig abgeschieden und in Wasserstoffperoxid Lösung gegeben. Die Partikel wurden daraufhin mittels dynamischer Lichtstreuung auf Selbstvortrieb untersucht.
Hybrid nanostructures combine the assets of the individual materials with a vast amount of new properties. In this work various metal nanoparticles have been synthesized and investigated on their optical properties. The synthesized metal nanoparticles have been implemented for potential applications, e.g. fabrication of a spaser or in solar cells. At first, the size, shape and refractive index effects of gold and silver nanoparticles have been investigated. The insight gained helps to optimize the synthesis of metal nanoparticles with specific optical properties needed for further applications. Optimized hybrid gold nanostructures have been synthesized and functionalized with dye molecules or quantum dots to investigate energy transfer effects. These hybrid structures have been optically pumped to achieve spasing. However, comparison with a theory showed that such metal nanostructures need unrealistic high gain to overcome the inherent losses and achieve spasing. Silver and gold nanoparticles have been synthesized for applications in thin film solar cells. It has been shown that silver lacks chemical stability and thus, if oxidized, the nanoparticles exhibit weak scattering and strong Ohmic losses. The oxide layer of silver nano-spheres could be via annealing. By contrast, gold nanoparticles, known for their higher stability, have been implemented in a perovskite solar cell. Such a modified solar cell showed an increase in efficiency by ~40% through increased generation of carriers. Anisotropic Janus carrier systems have been synthesized and functionalized with metal nanoparticles. Gold nanoparticles have been deposited either uniformly or on one lobe only of the dumbbell-shaped carrier system by using its chemical anisotropy. These gold nano¬particles have been grown to a gold shell. Platinum nanoparticles have been deposited on a single lobe and its self-propelling ability in a chemical fuel was investigated by means of dynamic light scattering.
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40

Pathak, Nilesh Kumar. "Study of plasmonic properties of metal nanoparticles and its applications." Thesis, IIT Delhi, 2016. http://localhost:8080/xmlui/handle/12345678/7040.

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41

Peiris, Gallage Sunari. "Pd and Pd based alloy nanoparticles as visible light photocatalysts for coupling reactions under ambient conditions." Thesis, Queensland University of Technology, 2017. https://eprints.qut.edu.au/113715/1/Gallage%20Sunari_Peiris_Thesis.pdf.

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This PhD thesis presents an investigation on the development of novel metal nanoparticle (NP) photocatalysts including non-plasmonic NPs and their alloy NPs for several important organic synthesis reactions. This study has provided solid information and advances in new materials design, synthesis and application for photocatalysis. The findings of this study demonstrate the use of visible light or sunlight to drive chemical reactions, which is an important aspect in the view of a sustainable and green chemistry.
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42

Wang, Jiyong. "Plasmonic Nanoantennas." Thesis, Troyes, 2017. http://www.theses.fr/2017TROY0021.

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Les réponses optiques linéaires et non linéaires de nanoparticules (NPs) plasmoniques fabriquées lithographiquement sont étudiées. La diffusion élastique donne une empreinte digitale des plasmons de surface des NPs, ces derniers exaltant les signaux optiques non linéaires. La dépendance en polarisation de la génération de seconde harmonique (SHG) montre un effet de basculement, qui est analysé à partir des décalages spectraux entre l’excitation et les resonances et des effets d'interférence de SHG. En régime de faible excitation, en plus d'un processus de recombinaison de paires électron-trou (e-h), les plasmons de particules (PPs) peuvent être excités par diffusion Auger avec une décroissance radiative donnant lieu à une photoluminescence métallique (MPL). Un modèle de l'efficacité quantique totale des émissions impliquant les deux contributions a été établi. En régime de forte excitation, une avalanche de photoluminescence multiphotonique (AMPL) est observée sur des hétérodimères couplés. Elle est interprétée par une recombinaison des porteurs chauds excités par ionisation multiphotonique (MI). Ce processus est assisté par le champ local des NPs. L'avalanche d’émission peut être évaluée en fonction de l'environnement du champ local et du facteur thermique des porteurs chauds. Le changement spectral du spectre d’émission indique une émission spontanée de paires e-h chaudes s'expliquant par une diminution du taux de diffusion des trous de la bande d lorsque la température augmente
Linear and nonlinear optical responses of lithographically fabricated plasmonic nanoparticles (NPs) are investigated. Elastic scattering offers the fingerprints for localized surface plasmon resonances of NPs, which enhance nonlinear optical signals. Excitation polarization dependent far-field radiation of second-harmonic generation (SHG) shows a flipping effect, which is analysed from the aspects of resonant excitation shifting and SH phase interference as size changes. The radiations of metallic photoluminescence (MPL) in the weak and strong radiation field are studied sequentially. In the weak excitation, besides a process via electron-hole (e-h) pair recombination, particle plasmons (PPs) can be excited via Auger scattering of photo-excited d-band holes and the radiative decay of which gives rise to PPs modulated MPL. A model of total emission quantum efficiency involving both contributions has been used to explain MPL radiation difference between the bulk and the NPs. In the strong excitation, avalanche multiphoton PL (AMPL) is observed from the coupled heterodimers, which is interpreted as the recombination of avalanche ionized hot carriers seeded by multiphoton ionization (MI). MI is greatly assisted by local field of coupled NPs at the excitation stage. The giant photon emission can be evaluated as a function of local field environment and thermal factor of hot carriers. The spectral change from PPs modulated profile to the one indicates spontaneous emission of hot e-h pairs is explained by the diminishment of d-band hole scattering rate as temperature increases
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43

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

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

QC 20140331

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Manley, Phillip [Verfasser]. "Simulation of Plasmonic Nanoparticles in Thin Film Solar Cells / Phillip Manley." Berlin : Freie Universität Berlin, 2016. http://d-nb.info/1107011779/34.

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45

Polyushkin, Dmitry Konstantinovich. "Investigation of plasmonic response of metal nanoparticles to ultrashort laser pulses." Thesis, University of Exeter, 2013. http://hdl.handle.net/10871/13521.

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In this thesis the interaction of ultrashort laser pulses with metal nanostructures is investigated via two different phenomena: coherent acoustic oscillations of nanoparticles and generation of THz pulses on metal surfaces. Both of these effects rely on the collective oscillations of free conduction electrons in metal surfaces, plasmons. The field of plasmonics gained a great interest in the last twenty years due to the unique properties of these surface modes. It is the effects of the resonant response of plasmonic structures to incident electromagnetic wave, in particular, in visible and infrared bands and the concentration of the electromagnetic field in small subwavelength regions with significant enhancement of the incident field that make plasmonics so attractive for various applications, such as biochemical sensing, enhanced fluorescence, surface-enhanced Raman scattering, and second harmonic generation, amongst others. Investigation of the coherent particle vibrations is performed using the pump-probe technique which allows measurement of the transient transmission signals. The expansion and subsequent contraction of the nanoparticle following the ultrashort laser pulse excitation lead to a shift of the plasmon band which can be traced by transient spectroscopy. We have investigated the effect of the particle thickness on the frequency of the fundamental vibrational mode. In addition, we measured the vibrational particle response during the particle shape deformation, both symmetrical and asymmetrical. Exploration of the THz generation phenomena on plasmonic structures was performed using THz time-domain spectroscopy, the method which allows tracing of the generated THz field in the time-domain. We were able for the first time to measure the THz pulses generated from arrays of metal nanoparticles. Our observations verify the role of the particle plasmon mode in the generation of THz pulses. In addition, by exploring the dependence of the THz emission on the femtosecond pulse intensity we showed a high nonlinearity in the THz generation mechanism. The experimental results were assessed in the context of a recently proposed model where the THz radiation is generated via the acceleration of the ejected electrons by ponderomotive forces. To reveal another proposed mechanism of the THz generation from plasmonic structures, namely optical rectification, we investigated the THz generation and electron emission from the arrays of nanoparticles and nanoholes. Our results suggest that both mechanisms may contribute to generation of THz pulses from the same sample under different illumination conditions. In addition to periodic arrays of nanoparticles and nanoholes, THz generation from random metal-dielectric films was investigated. The microstructuring of such films allowed selective THz frequency generation which was explained by a model of dipole THz emitters. In addition, the effects of low temperature and pressure on the THz generation efficiency were investigated.
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46

Shah, Raman Anand. "Orientational and quantum plasmonic effects in the optics of metal nanoparticles." Thesis, The University of Chicago, 2014. http://pqdtopen.proquest.com/#viewpdf?dispub=3638691.

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The classical theory of plasmonics envisions spherical nanoparticles obeying classical electrodynamics. Modern colloidal synthesis of noble metal nanoparticles, in tandem with emerging methods of nanoparticle assembly, transcends the assumptions of this theory. First, strongly nonspherical particles give rise to optical spectra with complicated orientation dependence. An interpolation method is introduced to connect electrodynamic simulation results, generally carried out at fixed orientations, with experimental optical spectra, such as those of randomly oriented ensembles. Second, the ability to manipulate and arrange multiple spherical particles in solution with optical binding demands efficient calculation of the optical forces giving rise to their preferred geometries. A coupled-dipole model is developed to allow for rapid optical force calculations that predict many of the phenomena seen in the laboratory. Third, the prospect of attaching semiconductor quantum dots to metal nanoparticles in the electromagnetic near-field raises new questions about how the quantum behavior of localized surface plasmons affects the nonlinear optical response of the coupled system. Investigating such questions yields several new predictions about the optical response of plasmon-exciton systems. Under ultrafast pulsed illumination, a reversal of a Fano resonance is predicted, turning a dip into a spike in the pulsed optical spectrum. When two quantum dots are coupled to the same metal nanoparticle, it is found that their individual couplings to a quantized plasmon can give rise to coherence between the quantum dots, in particular a state enriched in an antisymmetric dark excitation that can be prepared with pulsed laser illumination. These theoretical tools and predictions, in addition to providing basic insight into plasmonic systems, will serve to guide further developments in colloidal synthesis, nanoparticle assembly, and optical applications.

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47

Wang, Yisu. "Fabrication and quantitative correlative light-electron microscopy of novel plasmonic nanoparticles." Thesis, Cardiff University, 2018. http://orca.cf.ac.uk/120089/.

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Metallic nanoparticles (MNPs) are attracting increasing interest for many applications in photonics, ranging from optoelectronic devices to bioimaging and biosensing. An advantage of these systems is that their optical properties, governed by their localised surface plasmon resonance, are widely tunable via the nanoparticle shape and size, which can be controlled via e.g. colloid synthesis. In that context, it is important to develop accurate experimental methods able to correlate the size and shape of an individual single MNP, measured with nanometric precision, with its individual optical properties. In this thesis, three different MNP systems, namely i) commercially-available Ag nanocubes of 75 nm edge; ii) Ag tetrahedra, bi-tetrahedra and decahedra in the 25 - 50 nm size range which was fabricated in-house using a plasmon-mediated photochemistry method; iii) Ag nanodimers was fabricated in-house via controlled self-assembly of polymer linkers onto commercial nominally spherical Ag nanoparticles of 40 nm diameter. Beyond fabrication, a substantial part of the work reported in this thesis describes the experimental protocol for correlative optical and transmission electron microscopy, which was developed and optimised, comprising reproducible deposition of these silver nanoparticles onto TEM grids, their optical characterisation via polarisation-resolved high-resolution dark-field and extinction micro-spectroscopy, and subsequent high-resolution TEM of the same particle. As proof-of-concept, the same Ag nanocubes of 75 nm edge were characterised optically in different dielectric environments, using solvents of different refractive index n; specifically, anisole (n=1.52), water (n=1.33), and air (n=1). The MNP scattering and extinction cross-section was determined in absolute units using an in-house developed quantitative measurement protocol, and the results are compared with numerical simulations using the measured geometry. These studies pave the way toward an in depth understanding of the relationship between geometrical and optical properties of MNPs of non-trivial shapes, which in turn have the potential to be exploited in innovative bioimaging and biosensing platforms.
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48

Seirafianpour, Nader. "Study of nanoparticles of SnO2 on Au and nanoparticles of TiO2 on Ag for plasmonic applications." Thesis, 2007. http://spectrum.library.concordia.ca/975528/1/MR34776.pdf.

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Nanolayered systems composed of a gold film coated by a granular tin dioxide layer, and a silver film coated by a granular layer of titanium dioxide are fabricated by combined sputtering/sol-gel methods. The conditions of the sol-gel synthesis and the substrate materials were adjusted with a particular attention to the aggregation effects, especially in the case of the gold/tin dioxide system. The dielectric particles are uniformly distributed on the metal surfaces and the films are smooth (mean roughness less than 6 nm). The components of the nanolayered systems prepared in this work are found to be crystalline and the sputtered metal is preferentially oriented on the substrate. Because of the low-temperature sol-gel method used for the synthesis, especially small (4-5 nm) crystallites of titanium dioxide (anatase allotropic phase) have been found with a narrow size distribution. Size and intensity enhancement effects have been evidenced in both systems and studied by micro-Raman spectroscopy. A particular attention is paid in this work to the optical properties of the nanolayered composites with an emphasis on the surface plasmon resonance. The near-normal reflection spectra are measured and the effect of the dielectric coating on both the surface plasmon band of the noble metal and the band gap absorption of the dielectric are investigated. The effective-medium theory is used to calculate the reflection curves. The simulated curves show a qualitative agreement with the experimental spectra. The possibility to use these systems in sensing applications is discussed.
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49

Cheng, Chun-Chin, and 鄭鈞智. "Plasmonic Properties of Two-Dimensional Au/Ag Core-Shell Nanoparticle Superlattices." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/14626032296668285280.

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50

Huang, Jheng-Long, and 黃正隆. "Plasmonics and Photocatalysis of Sputtered Ag Nanoparticles Impregnated in N-TiO2 Thin Films." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/7wa4g7.

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碩士
國立東華大學
材料科學與工程學系
106
In this study, reactive magnetron sputtering was used to prepare different nitrogen doped titanium dioxide film (N-TiO2), which was combined with silicon dioxide layers and Ag nanoparticles (Ag NPs) to form a sandwich multilayer structure. The surface plasmon effect of Ag NPs could enhance the absorption of visible light of the film, and might improve the photocatalytic properties of titanium dioxide. The structure and crystallinity of the films were analyzed by XRD. The elemental composition and bonding of the films were examined by XPS. UV-vis spectrotometer was used to study the absorption phenomena of the films. The photocatalytic efficiency properties of the films under visible-light illumination were evaluated by measuring the decomposition rate of methylene blue in aqueous solution. From the experimental results, with the increase of silver sputtering time, the content and the size of silver nanoparticles increased which resulted in enhancement of visible light absorption of the films, but the rate of increase is limited. The silver nanoparticles may combine with the oxygen in the air or with the oxygen of TiO2 films and get oxidized, which reduce the surface plasmon effect of the nano-silver and as a result decrease the visible light absorption of the film. For this reason, SiO2 layers were deposited above and below silver layer to protect from oxidizing. At 30 seconds (Ag30-NT) deposition time of Ag, the distribution of Ag nano-particle size is uniform, so we used this parameter to deposit N-TiO2/SiO2/Ag/SiO2/N-TiO2 multilayer. This structure can provide Ag NPs with good surface plasmon effect and enhance the absorbance of the films in the visible light. However, the film didn’t show significant photocatalytic property. The possible reason is that SiO2 layer is too thick, which makes electron and hole pairs of the film hard to reach the surface of the film and could not exhibit significant photocatalytic property. When the nitrogen flow rate is 20 sccm, N-TiO2 has 16.9 at% of nitrogen content. The phases of the film obtained were anatase, Ti3O5 and TiN. The absorption in the visible light of 20 sccm nitrogen doped with TiO2 (N20T) is 3-4 times higher than TiO2 film. In addition, depositing anatase TiO2 on sample N20T, improved the photocatalytic phenomenon about 80% compared to that of pure TiO2 films. So the catalytic properties of photocatalyst films were affected by the absorbance and surface properties of the films.
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