Thèses : « Magneto plasmonic »

1

Li, Zhi. « Controlled nanotherapies using magneto-plasmonic nanodomes ». Doctoral thesis, Universitat Autònoma de Barcelona, 2019. http://hdl.handle.net/10803/667779.

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Con el objetivo de mejorar la concentración de los agentes terapéuticos dentro de tumores y maximizar sus efectos terapéuticos, esta Tesis se centró en el desarrollo de nuevos y versátiles nanocúpulas magneto-plasmónicas (i.e., nanopartículas dieléctricas con semicubiertas plasmónicas y ferromagnéticas) activadas y controladas externamente por luz y campos magnéticos, para la activación, amplificación y control eficiente de nanoterapias. La innovadora combinación de procesos de fabricación “top-down” y “bottom-up” nos ha permitido: i) fusionar nanomateriales que difícilmente podrían combinarse mediante síntesis química, ii) sintonizar las propiedades ferromagnéticas y ópticas, iii) lograr una funcionalización simple y una dispersión directa en soluciones acuosas, y iv) mantener bajo costo y escalabilidad. En primer lugar, desarrollamos nanocúpulas de Fe/Au con núcleos fluorescentes para terapias fototérmicas magnéticamente amplificadas y contraste de imagen multimodal. La variación del grosor de las capas de Fe y Au permitió obtener nanopartículas ferromagnéticas monodominio o con vórtice, coloidalmente estables, y con propiedades ópticas ampliamente sintonizables. Las capas gruesas de Fe proporcionaron una fuerte supresión de la dispersión y una alta absorción de la luz infrarroja cercana, que fueron clave para demostrar una alta eficiencia de conversión fototérmica (65%). La capacidad de concentrar magnéticamente las nanocúpulas en la región iluminada mejoró aún más la eficiencia de calentamiento local. La semi-cubierta de Fe/Au y el núcleo de polímero fluorescente proporcionaron intensos contrastes T2 en resonancia magnética nuclear, en absorción de rayos X y en fluorescencia. Los resultados in vitro mostraron una baja citotoxicidad y efectos fototérmicos mejorados magnéticamente para la erradicación de células cancerosas, lo que destacó el potencial biomédico. Para ganar control sobre los efectos fototérmicos, en la segunda parte desarrollamos un nuevo concepto de nano-calentadores/termómetros simultáneos, basado en la rotación magnética eficiente de las nanocúpulas magneto-plasmónicas altamente anisótropas. El análisis de la rotación de las nanocúpulas en función de la frecuencia magnética, permitió cuantificar la reducción de la viscosidad en el fluido que rodea a las nanocúpulas calentadas ópticamente, como un nuevo principio de nanotermometría. Estos nanotermómetros mostraron un límite de detección bajo de 0.05ºC, independencia de su concentración y un sistema detección mucho más simple y económico que los nanotermómetros luminiscentes. La capacidad de integrar el calentamiento y la termometría en una única nanoestructura y el uso del mismo láser para calentar y detectar fueron ventajas relevantes que pudieron demostrarse incluso en dispersiones celulares altamente concentradas. El objetivo final de la Tesis fue maximizar el potencial biomédico de las nanocúpulas para nanoterapias contra el cáncer mediante el desarrollo de nanocápsulas magnetoplasmónicas completamente biodegradables de PLGA@Fe/SiO2 cargadas con un fármaco, para conseguir: i) mayor biodegradabilidad, ii) reforzamiento del control magnético, iii) alta eficiencia fototérmica en ambas ventanas biológicas del infrarrojo cercano (63-67%), iv) mayor contraste de T2 en resonancia magnética nuclear y v) nanotermometros y biosensores integrados. Las nanocápsulas sin fármaco mostraron una toxicidad muy baja en cultivos celulares de largo plazo e in vivo en ratones. Se explotó el alto contraste de T2 para monitorizar la biodistribución in vivo de las nanocápsulas después de la inyección intravenosa, que mostró una acumulación en el hígado 1 h después de la inyección, y una recuperación casi total después de 96 h. Estos resultados preliminares son alentadores para su aplicación en terapias locales multiactivas. En conclusión, hemos mostrado cómo una estrategia de nanofabricación híbrida podría explotarse para desarrollar nanoestructuras con fuertes propiedades ferromagnéticas y plasmónicas que permitan el control y actuación externo y la visualización no invasiva. Los prometedores resultados preliminares in vitro e in vivo promueven un mayor desarrollo de esta nueva nanotecnología para aplicaciones clínicas.
With the aim of improving the concentration of the therapeutic agents inside tumours and maximizing their therapeutic effects, this Thesis focused on developing novel versatile magneto-plasmonic nanodomes (i.e. dielectric nanoparticles with plasmonic and ferromagnetic semi-shells) externally actuated and controlled by light and magnetic fields for efficient nanotherapy activation, amplification and control. The innovative combination of bottom-up and top-down fabrication processes have enabled us: i) merging nanomaterials that could be hardly combined by chemical synthesis, ii) fine tuning the magnetic and optical properties, iii) achieving simple functionalization and direct dispersion in water solutions, and iv) keeping low cost and scalability. Firstly, we developed Fe/Au nanodomes with fluorescent cores for magnetically amplified photothermal therapies and multimodal imaging. The variation of the Fe and Au layers thickness enabled attaining colloidally stable single domain or vortex ferromagnetic nanoparticles with widely tunable optical properties. Thick Fe layers provided strongly supressed scattering and high optical absorption in the near infrared, which were key to demonstrate high photothermal conversion efficiencies (ca. 65%). The capacity to magnetically concentrate the nanodomes at the illuminated region enhanced even further the local heating efficiency. The Fe/Au semi-shell and the fluorescent polymer core provided intense contrasts in T2 nuclear magnetic resonance, X-ray absorption, and fluorescence. The in vitro results showed low cytotoxicity and magnetically enhanced photothermal effects for cancer cell eradication, which highlighted the biomedical potential. To gain control on the photothermal effects, in the second part we developed a novel simultaneous nano-heating/thermometry concept, based on the efficient magnetic rotation of highly anisotropic magneto-plasmonic nanodomes. By analyzing the nanodomes rotation as a function of the magnetic frequency, we quantified and monitored the viscosity reduction in the fluid surrounding the optically heated nanodomes, as novel nanothermometry concept. This nanothermometers showed a low detection limit of 0.05ºC, independence on their concentration, and much simpler and cost-effective detection setup than luminescent nanothermometers. The capacity to integrate heating and thermometry in a single nanostructure and using the same laser for heating and detecting were relevant advantages that could be demonstrated even in highly concentrated cell dispersions. The final goal of the Thesis was maximizing the biomedical potential of the nanodomes for cancer nanotherapies by developing fully biodegradable drug loaded PLGA@Fe/SiO2 magnetoplasmonic nanocapsules to achieve: i) improved biodegradability, ii) reinforced magnetic actuation, iii) high photothermal conversion efficiency in both near-infrared biological windows (63-67%), iv) higher T2 contrast in nuclear magnetic resonance, and v) integrated nanothermometry and biosensing. The unloaded nanocapsules showed very low toxicity in vitro in long-term cell cultures, and in vivo in mice. The high T2 contrast was exploited to monitor the in vivo biodistribution of the nanocapsules after intravenous injection, which showed accumulation in the liver 1h after the injection, and almost total recovery after 96h. These preliminary results are encouraging for their application in multi-active local therapies. In conclusion, we have shown how a hybrid nanofabrication strategy could exploited to develop nanostructures with strong ferromagnetic and plasmonic properties enabling external control and non-invasive visualization. The in vitro and preliminary in vivo results encourage further technological development of this novel nanotechnology for clinical applications.

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2

George, Sebastian. « Optical and Magneto-Optical Measurements of Plasmonic Magnetic Nanostructures ». Thesis, Uppsala universitet, Materialfysik, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-229511.

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At the interface between a metal and dielectric, it is possible for an electromagnetic wave to couple with the conduction electrons of the metal to create a coupled oscillation known as a surface plasmon. These surface plasmons can exhibit properties which are not shared with their purely electronic or electromagnetic components. Such unique properties include the ability to transmit plasmonic waves through sub-wavelength spaces, opening up the possibility of combining the high data density seen in photonics-based information technologies with the nanometer-scale electronic components of modern integrated circuitry. Other plasmon properties such as the highly resonant nature of plasmon excitation may potentially lend themselves to novel cancer treatments and medical probing techniques. In order to develop such technologies, a deeper understanding of surface plasmons and their relationship with a material’s properties and structure is necessary. In the present work, angle- and energy-resolved optical measurements for a square lattice of circular Fe20Pd80 islands are presented in the form of reflectivity and transmission maps, along with higher resolution reflectivity, transmission, and TMOKE measurements for a few specific wavelengths. A theoretical model describing the connection between plasmonic and magneto-optical behavior is described and compared with the experimental data, showing a very high correlation.

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Huber, Jana. « Plasmonic resonances in metallic nanoarrays ». Thesis, Uppsala universitet, Materialfysik, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-262269.

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The optical and magneto-optical response of plasmonic resonances in metallic nanoarrays out of square structures, either in holes or islands, were investigated. The excitation of the Bragg Plasmons takes place within a grating. Significant differences in the excited plasmon modes were seen by using p- or s-polarized light as well between the holes and islands sample. In order to investigate magneto-optical response from the magnetic nanostrucures, transverse magneto-optical Kerr effect (TMOKE) measurements were done with the result that there is a difference in holes and islands sample. Contrary to what is generally expected for the polarization dependence of TMOKE, a TMOKE signal for s-polarized light on the holes sample was measured.

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Brynolf, Max, et Rohini Sengupta. « Magneto-Plasmonic Gold & ; Nickel Core-Shell Structures ». Thesis, Uppsala universitet, Materialfysik, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-387353.

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The presented project explores the optical properties of magnetoplasmonic Au/Ni core-shell structures. The work aims at controlling dimensions and parameters in order to influence and analyze the optical properties of the nanostructures. The softwares utilized for the simulations were COMSOL Multiphysics 5.1 and MATLAB. Experimental results were acquired from labs done at Ångströms laboratory. From the research based study where the gold to nickel ratio was influenced, it was observed that the transmissions for the nanostructures at the differing wavelengths produced transmissions of similar bearings. Modes for certain wavelengths were found in correspondence with the transmissions and could potentially render explanations for influence on the optical properties of the nanostructures. Conclusively, it can be stated that the optical properties of the nanostructures could be influenced and controlled by varying the dimensions and properties of the said structure. Differing dimensions corresponded to noteworthy changes in the cross sections, the transmissions as well as the mode formations.

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Loughran, Thomas. « Exploration of plasmonic antennas, for sub-wavelength magneto-optical Kerr imaging ». Thesis, University of Exeter, 2016. http://hdl.handle.net/10871/28077.

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This thesis outlines work performed with the intention of producing a novel near- field magneto-optical scanning microscope. This scanning microscope utilises a near field probe, produced through modification of existing atomic force micro- scopy (AFM) probes. In order to achieve the goal of strongly sub-wavelength res- olution imaging of magneto-dynamics, studies of planar plasmonic structures, and their interaction with magnetic materials were made. This was done in order to gain a better understanding of the complex interaction between plasmonic anten- nas, and magnetic materials. Investigations of planar systems, began with finite element modelling of the magneto optical Kerr effect (MOKE) effect, and its in- teraction with plasmonic structures. Initial modelling demonstrated the suitability of the commercial finite element modelling software ”COMSOL Multiphysics" for modelling magneto-optical effects. A series of plasmonic antennas were in- troduced to this model. The simplest of these (a gold disc of 140nm diameter) showed enhancement of the MOKE signal at resonance of up to 40x. A cut- cross antenna (consisting of two crossed cavities of 20nm width, and variable length and depth), which had been selected as a promising candidate for high field confinement, showed a generally smaller enhancement. However the field distribution from these structures was more suitable for the eventual near field microscopy applications. Similar real world structures were fabricated in mul- tilayer stacks consisting of P t(3nm)/ 4x[Co(0.5nm)/ P t(3nm)]/ T a2 O5 (various)/ 5 Au(100nm) layers. This was accomplished by focussed ion beam lithography (FIB) lithography through the gold layer. Magneto-optical characterisation of these structures was not possible, and this was believed to be due to FIB induced gal- lium poisoning of the magnetic layers. A gold floating technique was pursued in order to circumvent the gallium poisoning. New structures fabricated on gold films were shown to be resonant at optical wavelengths, through bright field trans- mission spectroscopic characterisation. However the floating technique in com- bination with the FIB beam produced capillaries that adhere to the underside of the gold film, which again prevent magneto-optical characterisation. Concurrent to the development of planar antenna structures, a platform for performing near field optical measurements of magnetic materials utilising an AFM, and modified probes was developed. This platform was used to obtain time resolved images of permalloy elements with a spatial resolution comparable to that achieved with a diffraction limited laser spot. A number of potential techniques for AFM probe modification that could be used to produce strongly sub-wavelength resolution time-resolved imaging have been explored.

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

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

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Spitzer, Felix [Verfasser], Ilya [Akademischer Betreuer] Akimov et Manfred [Gutachter] Bayer. « Magneto-optical intensity effects in hybrid plasmonic structures / Felix Spitzer ; Gutachter : Manfred Bayer ; Betreuer : Ilya Akimov ». Dortmund : Universitätsbibliothek Dortmund, 2019. http://d-nb.info/1178115887/34.

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Piatek, Anna [Verfasser], et Stephan [Akademischer Betreuer] Barcikowski. « Laser generated magneto-plasmonic Fe-Au Nanoparticles : Formation, Real Structure and Properties / Anna Piatek ; Betreuer : Stephan Barcikowski ». Duisburg, 2020. http://d-nb.info/1218465328/34.

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Pohl, Martin [Verfasser], Ilya [Akademischer Betreuer] Akimov et Heinz [Gutachter] Hövel. « Ultrafast optical phenomena in magneto-plasmonic crystals and magnetically ordered materials / Martin Pohl. Betreuer : Ilya Akimov. Gutachter : Heinz Hövel ». Dortmund : Universitätsbibliothek Dortmund, 2014. http://d-nb.info/1105476111/34.

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Loiselet, Ophelliam. « Synthèse et caractérisation d’agrégats bimétalliques pour la magnéto-plasmonique ». Thesis, Lyon, 2018. http://www.theses.fr/2018LYSE1033/document.

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Depuis plusieurs années les physiciens de la matière condensée s'intéressent aux propriétés optiques et magnétiques des nanoparticules métalliques. Deux propriétés restent largement étudiées : les résonances plasmon localisées et l'anisotropie magnétique à l'échelle nanométrique. Ces deux effets résultant de propriétés électroniques bien différentes sont habituellement rencontrés dans des nanosystèmes distincts. Depuis les années 2000 des études ont montré qu'il était possible de bénéficier de ces deux caractéristiques dans un seul et même système nanométrique. Dans cette thèse, nous nous intéresserons à la combinaison des propriétés magnétiques et plasmoniques dans des systèmes de taille inférieure à la dizaine de nanomètres: les agrégats bimétalliques de CoAg et de CoAu synthétisés par voie physique sous ultravide encapsulés en matrice (alumine et carbone). Nous nous intéresserons à la structure de ces agrégats bimétalliques de différentes stœchiométries et à l'effet de leur environnement à travers l'étude de leurs propriétés optiques, magnétiques et électroniques (par spectroscopie électronique par perte d'énergie (EELS) sur des particules individuelles). Nous montrerons l'effet de la matrice, carbone ou alumine, sur la structure des agrégats ainsi que sur leurs propriétés magnétiques (moment par agrégat, anisotropie). En optique nous verrons également l'importance de la stœchiométrie entre métal noble et cobalt sur les phénomènes d'amortissement et de décalage de résonance plasmon. Enfin nous montrerons la répartition spatiale des plasmons de surface sur des particules unique par des mesures de STEM-EELS
For several years condensed matter physicists have been interested in the optical and magnetic properties of metallic nanoparticles. Two properties remain largely studied: localized plasmon resonances and magnetic anisotropy at the nanoscale. These two effects resulting from very different electronic properties which are usually encountered in separate nanosystems. Since the 2000's, studies have shown that it is possible to benefit from these two characteristics in a single nanometric system. In this thesis, we will focus on the combination of magnetic and plasmonic properties in systems of size less than ten nanometers: bimetallic clusters of CoAg and CoAu synthesized physically under ultrahigh vacuum and embedded in a matrix (alumina and carbon). We will study the structure of these bimetallic clusters of different stoichiometries and the effect of their environment through the investigation of their optical, magnetic and electronic properties (by electron energy loss spectroscopy (EELS) on individual particles ). We will show the effect of the matrix, carbon or alumina, on the structure of the clusters as well as on their magnetic properties (moment by cluster, anisotropy). In optics we will also see the importance of stoichiometry between noble metal and cobalt on the phenomena of the damping and shifting of the plasmon resonance. Finally we will show the spatial distribution of surface plasmons on single particles by STEM-EELS measurements

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Scales, Christine. « Magneto-plasmons in optical slab waveguides ». Thesis, University of Ottawa (Canada), 2004. http://hdl.handle.net/10393/26765.

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The effect of an externally applied magnetic field on the propagation characteristics of a plasmon-polariton wave supported by an infinitely wide thin metal waveguide was investigated. In order to do so, the dispersion relation was derived, from Maxwell's equations, enabling accurate modelling of the situation of interest. The general dispersion relation, including the constraint equation, for magneto-plasmons was derived in general, and then, specifically for a magnetic field applied along three orthogonal cartesian axes. The losses in the metal were included in the dispersion equation so that a better understanding of the influence of an externally applied magnetic field may be provided. The dispersion relation is used as the basis of a software model of magneto-plasmons in thin metal films. This model is validated against specific cases in the literature with and without an externally applied magnetic field. The specific formulations in the literature were deemed to be incorrect, and have been corrected and the results have been interpreted. The model is then used to simulate thin gold films bounded by silicon dioxide at an infrared wavelength. The modelling results include the effect of the externally applied magnetic field on the propagation constant and the corresponding field components for all three Cartesian orientations of externally applied magnetic field. The results from these simulations are presented and interpreted. (Abstract shortened by UMI.)

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Zheng, Wei. « Nonlinear Optical Studies of Photoelastic Effect and Magneto-Plasmonics ». W&M ScholarWorks, 2014. https://scholarworks.wm.edu/etd/1539623369.

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Nonlinear optical (NLO) processes are optical phenomena involving a nonlinear response to an applied light field. Two kinds of nonlinearities are studied in this dissertation: magnetic-induced second-harmonic generation (MSHG) interacting with surface plasmon, called "nonlinear magnetoplasmonics" (NMP), and the nonlinear index induced by a strong pump beam in Titanium doped sapphire crystal, referred to as population-induced nonlinear index effect.;The fundamentals of the major effects involved are discussed, which include: surface plasmon and its field enhancement effect, MSHG technique and phenomenological calculations, the contrast ratio of magnetic switching, the calculation of lensing effects, population induced strain, and photoelastic effect. Furthermore, the experimental techniques and setup are presented. Two ultrafast laser systems and the design of a spatially and temporally homogenized chirped pulse amplifier are also elaborated, because these are the most important devices in the experiments.;In the study of population-induced nonlinear index effect, a fast measurement system is developed and one of the photoelastic constants of Ti:sapphire is obtained, which is useful to optimize Ti:sapphire lasers and amplifiers. In the study of NMP, the MSHG signal enhancement effect and the magnetic contrast tuning effect are discovered in a single crystal iron film. The two jump switching process induced by the cubic magnetic anisotropy of the iron film opens the way for simultaneously investigating both longitudinal and transverse magnetization components regardless of the external magnetic field. This study has potential usage in quaternary magnetic storage systems because it enables the read-out of all four magnetization states from crystalline iron with high contrast ratio, and it is also of interest for bio-chemical sensor applications due to its very high surface sensitivity and simple structure.

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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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Bhatta, Hari Lal. « UV Magnetic Plasmons in Cobalt Nanoparticles ». Thesis, University of North Texas, 2019. https://digital.library.unt.edu/ark:/67531/metadc1505221/.

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The main goals of this research were to fabricate magnetic cobalt nanoparticles and study their structural, crystal structure, optical, and magnetic properties. Cobalt nanoparticles with average particle size 8.7 nm were fabricated by the method of high temperature reduction of cobalt salt utilizing trioctylphosphine as a surfactant, oleic acid as a stabilizer, and lithium triethylborohydride as a reducing reagent. Energy-dispersive X-ray spectroscopy (EDX) analysis confirmed the formation of cobalt nanoparticles. High resolution transmission electron microscopy images show that Co NPs form both HCP and FCC crystal structure. The blocking temperature of 7.6 nm Co NPs is 189 K. Above the blocking temperature, Co NPs are single domain and hence showed superparamagnetic behavior. Below the blocking temperature, Co NPs are ferromagnetic. Cobalt nanoparticles with a single-domain crystal structure support a sharp plasmon resonance at 280 nm. Iron nanoparticles with average particle size 4.8 nm were fabricated using chemical reduction method show plasmon resonance at 266 nm. Iron nanoparticles are ferromagnetic at 6 K and superparamagnetic at 300 K.

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Werra, Julia Franziska Maria. « Probing plasmonic nanostructures ». Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät, 2016. http://dx.doi.org/10.18452/17658.

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Elektrische und magnetische Emitter können zur Erforschung unterschiedlicher plasmonischer Nanostrukturen genutzt werden. Indem wir die Änderung der Abstrahldynamik und in der Lebensdauer bestimmen, detektieren wir die photonische lokale Zustandsdichte. Diese Zustandsdichte, die eine Eigenschaft der Umgebung ist, ermöglicht uns nicht nur Rückschlüsse auf die elektronischen und andere physikalische Eigenschaften dieser zu treffen sondern auch die allgemeinen Eigenschaften der plasmonischen Nanostruktur im Bezug auf Licht-Materie Kopplung zu bestimmen. Eine starke Licht-Materie-Kopplung ist für die zukünftige Anwendung im Bereich der Quantentechnologien wichtig. Wenn Emitter hierbei mit plasmonischen Nanostrukturen koppeln, fokussieren letztere nicht nur das emittierte Lichts an der Oberfläche im Subwellenlängenbereich sondern ermöglichen durch die Feldüberhöhung an der Oberfläche auch eine starke Licht-Materie-Kopplung. In der Arbeit konzentrieren wir uns auf zwei grundlegend unterschiedliche plasmonische Systeme: zunächst untersuchen wir analytisch den Einfluss von Graphen auf elektrische und magnetische Emitter und diskutieren dann die Lebensdaueränderungen und Strahlungsdynamiken in der Nähe von Silber- und Goldnanostrukturen. Im ersten Teil der Arbeit analysieren wir den Einfluss von Graphen mit einer Bandlücke auf den Emitter und zeigen Möglichkeiten zur experimentellen Bestimmung der Bandlücke auf. Im zweiten Teil modellieren wir die Propagation elektromagnetischer Felder im dreidimensionalen Raum mit Hilfe der Diskontinuierlichen Galerkin Zeitraum Methode mit erweiterten Funktionalitäten. Diese verwenden wir sowohl zur theoretischen Modellierung des ersten dreidimensionalen Fluoreszenlebensdauerabbildungsmikroskopie mit einem einzelnen Quantenemitter als auch zur selbstkonsistent Beschreibung von Emittern in der Nähe eines Goldpentamers. Die Kombination der Studien betont die Stärke von Emittern elektrische, optische und magnetische Eigenschaften zu detektieren.
Electric and magnetic emitters can be used to probe different plasmonic nanostructures. By determining the modification of the radiation dynamics and the lifetimes, we can measure the photonic local density of states. This, being a property of the enviroment, does not only allow us to draw conclusions regarding the electronic and other physical properties of the latter but also regarding the general light-matter coupling properties of the plasmonic nanostructure. A strong light-matter coupling is important for future applications in quantum technology. If emitters couple specifically to plasmonic nanostructure, the latter do not only focus the emitted light at the sub-wavelength scale at the surface of the structure but also allow for such a strong light-matter coupling due to the field enhancement at the surface. In this work, we focus on two different basic plasmonic systems: first, we study analytically the influence of graphene on electric and magnetic emitters, and second we discuss lifetime modifications and radiation dynamics close to silver and gold nanostructures. In the first part of this work, we specifically focus on the influence of graphene exhibiting a finite band gap on the emitter. In the second part, we model the propagation of electromagnetic fields in three-dimensional space making use of the discontinuous Galerkin time-domain method with extended functionalities. This framework we apply to model the first three-dimensional scanning-probe fluorescence-lifetime imaging microscopy by use of a single quantum-emitter as well as for a self-consistent description of emitters in the proximity of a gold pentamer. The combination of these studies stress that the strength of emitters lies in the detection of electronic, optical and magnetic properties.

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Scaramuzza, Stefano. « Laser Ablation Synthesis in Solution and Characterization of Magnetic-plasmonic alloy nanoparticles ». Doctoral thesis, Università degli studi di Padova, 2016. http://hdl.handle.net/11577/3424317.

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In the history of nanoparticle synthesis, combining the properties of different elements in a single nanostructure has always been an important objective. In particular, alloy nanoparticles (NPs) are attracting a great research interest from the scientific community, since alloying is a way for combining different properties in a single nano-object, and obtaining peculiar structures such as NPs with magnetic and plasmonic response. Besides, by acting on alloy composition, it becomes possible to finely tune a given physical or chemical property, such as intensity and position of the surface plasmon resonance in Ag-Au NPs, or the efficiency of hydrogenation of nitro-substituted aromatics with Ni-Pd nanoalloys. The most frequent approach for the synthesis of metal alloy NPs relies on wet-chemistry methods. There are many available reactions, such as the one used to obtain in one step Ag-Au alloy NPs by co-reduction of HAuCl4 and AgNO3, and they depend on the type of metal precursors and solvents employed. Other chemical methods have also been used, such as radiolysis, electrochemistry, sonochemistry and biosynthesis. All these methods run in thermodynamic or near-to-thermodynamic equilibrium conditions, thus limiting the type and composition of achievable nanoalloys. Physical methods such as ion implantation and molecular beams can also produce metastable nanoalloys, but are less frequently employed because of the limitations in the scalability and use of final products. With these methods, NPs are produced inside a solid matrix or on a substrate where they often undergo irreversible agglomeration. A different and more promising physical method for the production of both thermodynamically stable and metastable alloy NPs consists in Laser Ablation Synthesis in Solution (LASiS). LASiS employs a pulsed laser focused on the surface of a bulk metal target for the generation of a colloidal solution of NPs. Following laser absorption by the bulk target, the ablation process takes place through the generation of a plasma plume and the formation of a cavitation bubble, where NPs form. The structure and composition of the NPs are determined by a number of ablation parameters, like laser power, pulse duration, solvent, target, and molecules available in the solvent. In recent years, LASiS has been employed to create metal alloy NPs such as Au-Ag, Pt-Au, Pt-Ir. In this PhD work, the synthesis of alloy nanoparticles by LASiS was investigated, considering in particular the Au-Fe and Ag-Fe systems. Au-Fe alloy nanoparticles were obtained by laser ablation of a bulk Au73Fe27 target. Different solvents were used to obtain more insight about the influence of the ablation liquid environment on the structure and composition of the nanoparticles. The plasmonic and magnetic properties of the nanoparticles were also studied in detail and, taking advantage from their coexistence, these nanoalloys were optimized as multimodal contrast agents for Magnetic Resonance Imaging, x-ray absorption computerized tomography, and surface enhanced Raman scattering (SERS) imaging. In-vitro and in-vivo tests of their biocompatibility and functionality as multimodal contrast agents were also carried out. Ag-Fe nanoparticles were synthesized in water and ethanol from targets with different composition. The nanoparticles were studied for their plasmonic and magnetic properties, and in-depth understanding of their complex structure required the use of various complementary techniques of analysis. Due to their magnetic properties, these nanoparticles were used to create customizable arrays for SERS analysis. Various nanoparticles parameters were studied to optimize the SERS efficiency of these arrays, such as surface coating with thiolated ligands or nanoparticles concentration. As a last step, the possibility of reusing these arrays was investigated. In summary, the application of LASiS to the synthesis of magnetic-plasmonic alloy NPs, which has been attempted in this thesis for the first time, opens several fascinating opportunities for the development of new multifunctional tools in various fields ranging from nanophotonics to nanomedicine.
Nella storia della sintesi delle nanoparticelle, unire le proprietà di differenti elementi in una singola nanostruttura è sempre stato un obiettivo molto importante. Le nanoparticelle di lega metallica attraggono molto l’attenzione dalla comunità scientifica interessata proprio perché creare una lega è un interessante modo di combinare molteplici proprietà in un singolo oggetto, ottenendo ad esempio nanoparticelle con proprietà magnetiche e plasmoniche. Con queste nanostrutture è inoltre possibile effettuare una messa a punto precisa ed accurata di una determinata proprietà fisica o chimica, come ad esempio la posizione del picco di risonanza plasmonico nelle particelle di lega Au-Ag, o l’efficienza dell’idrogenazione di molecole aromatiche nitro-sostituite con leghe Ni-Pd. L’approccio più frequentemente utilizzato per la sintesi di nanoparticelle in lega metallica sfrutta la sintesi chimica in fase liquida. Molteplici procedure sono state utilizzate in questo ambito, come ad esempio la co-riduzione in singolo stadio di HAuCl4 e AgNO3. Altri metodi chimici possibili sono la radiolisi, la sintesi elettrochimica e anche la biosintesi. Tutti questi metodi lavorano in condizioni di equilibrio termodinamico, e questo induce delle severe limitazioni alla varietà di struttura e composizione ottenibili per le nanoleghe. Metodi fisici come l’impianto ionico o l’epitassia con raggi molecolari possono produrre nanoleghe metastabili, ma sono usate più raramente a causa dei limiti insiti nella scalabilità della produzione di nanoparticelle e nella difficoltà di utilizzo quando le particelle sono inglobate in matrici solide o sono aggregate (spesso irreversibilmente) su un substrato. Un metodo differente e promettente per la produzione di nanoparticelle in lega è denominato Laser Ablation Synthesis in Solution (LASiS), ovvero ablazione laser in soluzione. Questo metodo prevede l’utilizzo di un laser ad impulsi focalizzato sulla superficie di un bersaglio metallico per generare nanoparticelle in soluzione. Dopo l’assorbimento dell’energia dell’impulso laser da parte del bersaglio metallico, il processo di ablazione avviene mediante la generazione di un plasma e, successivamente, di una bolla di cavitazione, nella quale le nanoparticelle si formano per essere poi raccolte sotto forma di soluzione colloidale nel liquido circostante. La struttura e la composizione delle nanoparticelle sono determinate da numerosi parametri, come la potenza del laser, la durata dell’impulso, il solvente impiegato, la presenza di eventuali molecole in soluzione. Recentemente, la tecnica LASiS è stataimpiegata per creare nanoparticelle in lega metallica, come oro-argento, platino-oro, o platino-iridio. In questa tesi di dottorato è stata affrontata la sintesi mediante LASiS di nanoparticelle in lega metallica a base di Au-Fe ed Ag-Fe, la cui composizione è metastabile. Nanoparticelle in lega Au-Fe sono state ottenute ablando un target Au73Fe27. Differenti solventi sono stati impiegati per ottenere una comprensione più approfondita dell’effetto della soluzione liquida sulla struttura e composizione delle nanoleghe ottenute mediante LASiS. Le proprietà plasmoniche e magnetiche di queste nanoleghe sono state studiate in dettaglio dal punto di vista sperimentale e con il supporto di modelli teorici. Inoltre, le nanoparticelle di Au-Fe sono state ingegnerizzate per un’applicazione specifica, quella di agenti di contrasto multimodali per imaging mediante risonanza magnetica nucleare, tomografia computerizzata da assorbimento di raggi x, e Raman amplificato tramite l’effetto di Surface Enhanced Raman Scattering (SERS). Nanoparticelle di Ag-Fe sono state ottenute mediante LASiS partendo da target bimetallici immersi in etanolo. Le proprietà magnetiche e plasmoniche delle nanoparticelle sono state studiate e messe in relazione con la complessa struttura cristallina, che ha richiesto l’utilizzo di numerose tecniche di indagine strutturale per essere compresa appieno. Grazie alle apprezzabili proprietà magnetiche, le nanoparticelle di Ag-Fe sono state utilizzate per realizzare arrays auto-assemblanti utili come substrati per analisi SERS. In conclusione, la LASiS si è rivelata essere uno strumento molto potente per sintetizzare nanoleghe multifunzionali. In particolare, le nanoparticelle magneto-plasmoniche, qui sintetizzate, studiate ed utilizzate per la prima volta, aprono affascinanti prospettive nella creazione di nuovi strumenti multifunzionali di interesse per vari campi, dalla nanofotonica alla nanomedicina.

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HICKERNELL, ROBERT KERR. « NONLINEAR AND MAGNETO-OPTIC EFFECTS ON LONG-RANGE SURFACE PLASMON POLARITONS ». Diss., The University of Arizona, 1987. http://hdl.handle.net/10150/184145.

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The properties of surface plasmon polaritons which propagate in optically nonlinear or magnetic media are investigated. Expressions for the electromagnetic fields of a multilayer stack are derived by modification of the Fresnel reflection coefficients. Original research on prism-coupled, nonlinear, long-range surface plasmon polaritons, and on bound and prism-coupled, long-range surface magnetoplasmon polaritons in a transversely-applied magnetic field, is compared to previous research on single-interface plasmon polaritons. The reflectance from prism-coupled, nonlinear surface plasmons is analyzed using the infinite plane-wave approximation and a substrate nonlinearity which depends on the square of the transverse-electric field. Bistable switching requires incident intensities two orders of magnitude smaller for the long-range mode than for the single-interface mode. The regime in which the approximations are valid is shown to extend beyond that of first-order perturbation theory to guided waves that are very near cutoff. The sign and location of the nonlinearity become significant for these waves. For positive nonlinearities, nonlinear wave analysis indicates an additional branch of the reflected intensity curve, due to self-focussing of the guided wave. Positive and negative nonlinearities exhibit different switching intensities. The propagation constant of the long-range surface plasmon of a magnetic metal film is shifted by the application of a transverse magnetic field. The sign and magnitude of the shift are highly dependent on the metal thickness and the refractive indices of the bounding media. The shift is manifested experimentally as a resonant modulation of the reflectance from the prism-coupled surface plasmon due to changes in the angular position and width of the plasmon resonance. Experimental prism-coupling to the long-range surface magnetoplasmon in thin nickel films confirms the theoretical expectations for a wide variety of sample parameters. The phase of the magneto-optic coefficient is determined from the angular profile of the reflectance modulation. Although the shift of the propagation constant may be two orders of magnitude smaller for the long-range mode, the modulation signal is the same order of magnitude for long-range and single-interface magnetoplasmons.

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Toal, Brian. « Fabrication and characterisation of nanowire arrays : magnetic and plasmonic interactions at the nanoscale ». Thesis, Queen's University Belfast, 2015. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.676613.

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In this thesis the fabrication and characterisation of nanostructured arrays are discussed. Nanowires, nanotubes and core-shell nanostructures are produced through electrodeposition into the pores of anodised aluminium oxide templates. The electrochemical process is optimised for all materials used. Using nickel, it is demonstrated that the dimensions of the nanowires within the template alter the wavelength position of a reflectivity minima associated with a sub-wavelength optical resonance, corresponding to enhancement of Kerr rotation. The magnetic properties are largely dictated by magnetostatic interactions resulting in an easy axis of magnetisation perpendicular to the nanowire long axis Cobalt nanowires produce a larger Kerr rotation than analogous nickel samples. The magnetic properties are altered by the uniaxial magnetocrystalline anisotropy, confirmed by x-ray diffraction to lie along the long axis of the nanowires. It is therefore possible to rotate the easy axis of magnetisation from the plane of the substrate to the nanowire long axis by increasing the aspect ratio and inter-wire separation. Cobalt nanotubes create a highly complex magneto-optical response with multiple resonances. Nickel-iron alloy nanowires were also made, and the results are compared for changing geometry as well as varying concentration levels. It is revealed through transmission electron microscopy that the grain structure is richly textured with nanocrystalline grains and high volume fraction of grain boundaries. The magnetoplasmonic properties of gold-core cobalt-shell nanowire arrays conclude the thesis. It is found that a nanometric cobalt layer is sufficient to demonstrate magnetic control over optical properties. The optical properties of the array are characteristic of the plasmonic resonances associated with the gold nanowires and the magnetic properties are similar to those of cobalt nanotubes. Combined, however, the wavelength and magnitude of the relative phase shift between P and S polarised components of incident light can be altered with the application of a magnetic field.

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

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

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Litti, Lucio. « Plasmonic and Magnetic Nanostructures for Multiplexing Detection and Multiple Imaging Techniques in Bionanomed ». Doctoral thesis, Università degli studi di Padova, 2015. http://hdl.handle.net/11577/3424704.

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In the last years nanotechnology is strongly influencing the progresses of medicine, in particular against cancer, both for diagnostic and therapeutic purposes. Nanostructures can be planned with properties useful for a specific application. However, the same nanostructure can be synthesized also for more diagnostic techniques. In addiction, one can also plan these nanostructures for what is called multiplexing, namely the presence in the same diagnostic signal of information related to many analytes at the same time. The nanostructures can be synthesized for obtaining targeting, which increases the ability of discriminating different type of tumour associated antigens or, in the case of therapeutic purposes, for the ability of being directed to a specific site. In the present thesis, nanostructures have been synthesized for their applications in particular with two techniques like surface enhanced Raman spectroscopy (SERS) and magnetic resonance imaging (MRI), which are complementary techniques for imaging. The nanostructures have been functionalized also with antibodies for targeting antigens. SERS exploits the huge enhancement of electromagnetic fields of plamonic nanostructures. It is shown that this technique can be used for quantitative measurements of clinically interesting anticancer drugs, with a linear range response in the order of nanomole per millimetre square of SERS active area, which is appropriate also for clinical purposes. It is also demonstrated how molecules with a poor Raman cross section could be revealed with the help of a protocol, called Reactive-SERS, which considers a simple photoactivated reaction. Nanoparticles are obtained with laser ablation and they are found easy to functionalize due to their unique naked surface. It is shown that their properties are useful in laser desorption ionization mass spectrometry. Used as a matrix, they are compared with chemically produced particles and with a widely used organic matrix and they always show the lowest background especially in the low mass region under 500 Da, which is important for the identification of small molecules. Multiplexing analysis are carried out with gold nanoparticles (AuNP) functionalized with different dyes, as SERS reporters, associated to different antibodies. The library of optimized thiolated reporters is increased and makes possible to investigate more complex biological samples. This application is also translated to the cultural heritage research field for the characterization of paint stratigraphic samples. Multimodal contrast agents are developed, coupling the SERS activity, typical of dye functionalized gold nanoparticles, with magnetic sensitive moieties, like iron atoms in alloy nanoparticles or with Gd3+ ions linked to gold nanoparticles. A new polymer, called SuperDOTA, is synthetized for achieving high Gd3+ loadings on the surface of nanoparticles. Preliminary results show that AuNPs, functionalized with both a SERS reporter dye and SuperDOTA-Gd, have useful properties for in vivo MRI tumour analysis and ex-vivo SERS imaging.
Negli ultimi anni le nanotecnologie stanno fortemente influenzando i progressi della medicina, in particolare contro il cancro, sia per quanto riguarda la diagnostica che la terapia. Le nanostrutture possono essere pianificate con proprietà utili per specifiche applicazioni. Ad ogni modo, la stessa nanostruttura può essere sintetizzata anche per più tecniche diagnostiche. In aggiunta, si possono ottenere nanostrutture per quel che viene chiamato multiplexing, ovvero la presenza nello stesso segnale diagnostico di informazioni relative a più analiti simultaneamente. Le nanostrutture possono essere sintetizzate per ottenere targeting, che aumenta l’abilità di discriminare differenti tipi di antigeni associati a tumori o, nel caso di obiettivi terapeutici, per l’abilità di raggiungere un sito specifico. Nella presente tesi, le nanostrutture sono state sintetizzate per applicazioni con due particolari tecniche come la spettroscopia Raman amplificata da superfici (SERS) e l’imaging per risonanza magnetica (MRI), che sono tecniche di imaging complementari. Le nanostrutture sono state altresì funzionalizzate con anticorpi per il riconoscimento di antigeni. Il SERS sfrutta l’enorme amplificazione dei campi elettromagnetici di una nanostruttura plasmonica. Viene mostrato che questa tecnica può essere usata per misure quantitative di farmaci antitumorali di interesse clinico, con un range di risposta lineare nell’ordine delle nanomoli per millimetro quadrato di superficie SERS attiva, che risulta appropriato anche per applicazioni cliniche. Viene in oltre dimostrato come molecole con una bassa sezione d’urto Raman possano essere rivelate con l’aiuto di un protocollo, chiamato Reactive-SERS, che sfrutta una semplice reazione fotoattivata. Le nanoparticelle sono ottenute per ablazione laser e risultano quindi facili da funzionalizzare a causa della loro peculiare purezza superficiale. Viene mostrato che le loro proprietà sono utili per la spettrometria di massa a ionizzazione per desorbimento laser. Usate come matrice, sono state confrontate con particelle prodotte chimicamente e con una matrice organica largamente utilizzata e hanno sempre mostrato un rumore di fondo inferiore, specialmente nella zona dei bassi pesi molecolari, sotto i 500 Da, che è una zona importante per l’identificazione di piccole molecole. L’analisi in multiplexing viene fatta con nanoparticelle di oro (AuNP) funzionalizzate con differenti coloranti, come SERS reporters, associati a differenti anticorpi. La libreria di coloranti tiolati ottimizzati è stata incrementata e rende possibile investigare campioni biologici più complessi. Questa applicazione è stata anche traslata alla ricerca applicata ai beni culturali per la caratterizzazione di campioni pittorici stratigrafici. Sono stati sviluppati agenti di contrasto multimodali, accoppiando l’attività SERS, tipica delle particelle di oro funzionalizzate con coloranti, e agenti sensibili a campi magnetici, come atomi di ferro in nanoparticelle di lega o ioni Gd3+ legati alle nanoparticelle di oro. Un nuovo polimero, chiamato SuperDOTA, è stato sintetizzato per raggiungere alte concentrazioni di Gd3+ sulla superficie delle nanoparticelle. Risultati preliminari mostrano che queste AuNP, funzionalizzate sia con coloranti SERS reporter che con SuperDOTA-Gd, hanno proprietà utili per analisi in vivo di tumori con MRI ed imaging ex vivo con SERS.

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Roccapriore, Kevin M. « Nanophotonics of Plasmonic and Two-Dimensional Metamaterials ». Thesis, University of North Texas, 2018. https://digital.library.unt.edu/ark:/67531/metadc1248498/.

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Various nanostructured materials display unique and interesting optical properties. Specific nanoscale objects discussed in an experimental perspective in this dissertation include optical metamaterials, surface plasmon sensors, and two-dimensional materials. These nanoscale objects were fabricated, investigated optically, and their applications are assessed. First, one-dimensional magnetic gratings were studied, followed by their two-dimensional analog, the so-called "fishnet." Both were fabricated, characterized, and their properties, such as waveguiding modes, are examined. Interestingly, these devices can exhibit optical magnetism and even negative refraction; however, their general characterization at oblique incidence is challenging due to diffraction. Here, a new method of optical characterization of metamaterials which takes into account diffraction is presented. Next, surface plasmon resonance (SPR) was experimentally used in two schemes, for the first time, to determine the transition layer characteristics between a metal and dielectric. The physics of interfaces, namely the singularity of electric permittivity and how it can be electrically shifted, becomes clearer owing to the extreme sensitivity of SPR detection mechanisms. Finally, ultra-thin two-dimensional semiconducting materials had their radiative lifetime analyzed. Their lifetimes are tuned both by number of atomic layers and applied voltage biasing across the surface, and the changes in lifetime are suspected to be due to quenching or enhancement of non-radiative process rates.

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Gupta, Maneesh Kumar. « Stimuli-responsive hybrid nanomaterials : spatial and temporal control of multifunctional properties ». Diss., Georgia Institute of Technology, 2012. http://hdl.handle.net/1853/45920.

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Recently, technological advancement and the promise of next-generation devices have created an overwhelming push for the continued miniaturization of active systems to the micro- and nanometer scale. In this regime, traditional mechanical systems are largely inaccessible and as a result new active or stimuli-responsive materials are required. The work presented in this dissertation provides an understanding of the responsive nature of polymer and biopolymer interfaces especially in contact with metal nanoparticles. This understanding was utilized in conjunction with top-down template-based and self-assembly fabrication strategies to create hybrid protein based films and active polymer-metal hybrids that exhibit large and well-defined modulation of mechanical and optical properties. These materials processing developments represent advancement in the current state of the art specifically in three major areas: 1. template-based top-down control of protein chain conformation, 2. high-throughput synthesis and assembly of strongly coupled plasmonic nanoparticles with modulated optical properties (both near- and far-field), 3. field-assisted assembly of highly mobile and non-close packed magnetic nanorods with capabilities for rapid actuation.

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Kana, Jean Bosco Kana. « Towards stimuli-responsive functional nanocomposites : smart tunable plasmonic nanostructures Au-VO2 ». Thesis, University of the Western Cape, 2010. http://etd.uwc.ac.za/index.php?module=etd&action=viewtitle&id=gen8Srv25Nme4_8032_1299494958.

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The fascinating optical properties of metallic nanostructures, dominated by collective oscillations of free electrons known as plasmons, open new opportunities for the development of devices fabrication based on noble metal nanoparticle composite materials. This thesis demonstrates a low-cost and versatile technique to produce stimuli-responsive ultrafast plasmonic nanostructures with reversible tunable optical properties. Albeit challenging, further control using thermal external stimuli to tune the local environment of gold nanoparticles embedded in VO2 host matrix would be ideal for the design of responsive functional nanocomposites. We prepared Au-VO2 nanocomposite thin films by the inverted cylindrical reactive magnetron sputtering (ICMS) known as hollow cathode magnetron sputtering for the first time and report the reversible tuning of surface plasmon resonance of Au nanoparticles by only adjusting the external temperature stimuli. The structural, morphological, interfacial analysis and optical properties of the optimized nanostructures have been studied. ICMS has been attracting much attention for its enclosed geometry and its ability to deposit on large area, uniform coating of smart nanocomposites at high deposition rate. Before achieving the aforementioned goals, a systematic study and optimization process of VO2 host matrix has been done by studying the influence of deposition parameters on the structural, morphological and optical switching properties of VO2 thin films. A reversible thermal tunability of the optical/dielectric constants of VO2 thin films by spectroscopic ellipsometry has been intensively also studied in order to bring more insights about the shift of the plasmon of gold nanoparticles imbedded in VO2 host matrix.

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Selvanathan, Pramila. « Photochromic switches for luminescence, plasmonic resonance, single molecule magnetic properties, and molecular wires for nano junctions ». Thesis, Rennes 1, 2016. http://www.theses.fr/2016REN1S145.

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Ce travail est consacré à la synthèse et la caractérisation des commutateurs et des fils moléculaires incorporant l'unité et le ruthénium organométalliques fractions photochromiques. La première partie traite de lanthanides complexe Yb combiné avec l'unité et le ruthénium acétylure fractions photochromiques afin de moduler la luminescence avec l'aide de redox et de stimuli lumineux. Dans la deuxième partie explique la combinaison d'unités DTE photochromiques avec des fragments acétylures de ruthénium pour fixer sur la surface de nanoparticules métalliques afin d'affiner leur résonance plasmonique grâce à la modification de l'environnement de surface en utilisant la lumière et redox stimuli. La troisième partie décrit la préparation de complexes de lanthanides combinés avec une unité photochromique spiropyranne pour commuter les propriétés SMM des complexes via photoisomérisation de l'unité spiropyranne. Dans la dernière partie, nous présentons la synthèse de Oligo (phénylène éthylène) Les fils moléculaires avec différents noyaux centraux afin d'obtenir une variété de fil avec différents niveaux d'énergie HOMO-LUMO pour vérifier l'effet de l'épinglage
This work is devoted to the synthesis and characterization of novel molecular switches and wires incorporating photochromic unit and ruthenium organometallic moieties. The first part deals with lanthanide Yb complex combined with photochromic unit and ruthenium acetylide moieties in order to modulate the luminescence with the help of redox and light stimuli. In the second part explained the combination of photochromic DTE units with ruthenium acetylide moieties to attach on the surface of metal nanoparticles in order to tune their plasmonic resonance through the surface environment modification by using light and redox stimuli. The third part describes the preparation of lanthanide complexes combined with a spiropyran photochromic unit in order to switch the SMM properties of the complexes via photoisomerization of the spiropyran unit. In the last part, we report the synthesis of Oligo(phenylene ethylene) molecular wires with different central cores in order to obtain various wire with different HOMO-LUMO energy levels to check the effect of pinning

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25

Mohammad, Jabeen Irrem Laareb. « Insights into the myristoylated c-Src N-terminal Regulatory Element ». Doctoral thesis, Universitat de Barcelona, 2021. http://hdl.handle.net/10803/672570.

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c-Src is a non-receptor tyrosine kinase that controls numerous cellular signaling pathways. c-Src implication in human cancers was brought into the attention in the 1980s. Since its discovery, unveiling of c-Src structural architecture and subsequent regulatory function focused on the folded domains cassette SH3-SH2-SH1(kinase), while the remaining N-terminal intrinsically disordered myristoylated SH4 and Unique domains were assumed to have a membrane-connecting function. c-Src membrane binding has been well-characterized as a two-prong association requiring the burial of its myristoyl moiety and the electrostatic interaction of the cluster of basic residues in the SH4 domain to the anionic lipids. Membrane binding of c-Src is mostly reversible, however accumulated evidence shows clustering and irreversible binding of a small fraction of c-Src molecules upon membrane anchoring. All the elements required for c-Src self-association are found in the N-terminal myristoylated SH4 domain. However, self-association through the strongly positively charged SH4 domain (+5 net charge) is counterintuitive. The structural basis of this self- association has been investigated in this thesis using Surface Plasmon Resonance. Performing individual mutations, we have determined that the alternate lysine residues at positions 5, 7 and 9 in the myristoylated SH4 domain enables c-Src self-association upon membrane binding. Further analysis reveals that the positive charge of the lysine residues is essential for clustering and thus a role of the lipids in the membrane as mediators of the c-Src self-association is proposed. Recently, it was shown that the (non-myristoylated) N-terminal region comprising the intrinsically disordered SH4-Unique domains and the adjacent globular SH3 domain formed a novel regulatory unit designated as the c-Src N-terminal Regulatory Element (SNRE). The (non- myristoylated) SNRE features an interdomain fuzzy complex, where the Intrinsically Disordered Regions: SH4 and Unique domains (IDR) maintain multiple weak contacts with the SH3 domain. The unavoidable question is whether the nature of this fuzzy complex is altered when the SH4 domain is in its native myristoylated form. In this thesis, characterization of the myristoylated SNRE has been performed using Nuclear Magnetic Resonance and various constructs of the SNRE in the myristoylated and non-myristoylated forms. We show that the myristoyl moiety increases the local concentration of the intrinsically disordered SH4 and Unique domains in the proximity of the SH3 domain by cooperatively favoring the intramolecular interactions that define the fuzzy complex. When c-Src is not bound to the membrane, the myristoyl moiety is harbored in the fuzzy interdomain complex through multiple binding sites in the SH3 domain. Finally, a preliminary characterization of the SNRE with the adjacent SH2 domain has revealed that the interface region connecting the SH3-SH2 could also be a key component of the SNRE.
c-Src es una tirosina quinasa no receptora que regula múltiples vías de señalización celular. Destaca su implicación en diversos tipos de cáncer en humanos. Desde su descubrimiento, el análisis de la arquitectura estructural de c-Src y posteriormente la función reguladora se centró en el casete de dominios plegados SH3-SH2-SH1 (quinasa), mientras que se asumió que la función de los dominios N-terminales intrínsecamente desordenados SH4 miristoilado y Unique era la unión a membrana. La asociación de c-Src a la membrana citoplasmática se caracteriza por la inserción del grupo miristoilo y la interacción electrostática del clúster de residuos básicos del dominio SH4 con los lípidos cargados negativamente. La interacción de c-Src con la membrana es en general reversible, aunque, se ha observado que una fracción minoritaria se une de manera permanente formando en su mayoría especies diméricas en la membrana. Esta dimerización de c-Src se produce mediante el dominio N-terminal SH4 miristoilado. Sin embargo, la autoasociación a través del dominio SH4 con una alta carga positiva (carga neta +5) es algo contradictoria. En la presente tesis se ha investigado la base estructural de esta autoasociación mediante Resonancia de Plasmones Superficiales. Mediante la realización mutaciones individuales en el dominio SH4 se determina que los residuos de lisina en las posiciones alternativas 5, 7 y 9 en el dominio SH4 miristoilado permiten la autoasociación de c- Src tras la unión a la membrana. Un análisis más detallado revela que la carga positiva de los residuos de lisina es esencial para la dimerización y, por lo tanto, se propone que los lípidos de la membrana son mediadores de la autoasociación de c-Src. Recientemente, se demostró que la región N-terminal (no miristoilada) que comprende los dominios intrínsecamente desordenados (SH4-Unique) y el dominio globular adyacente SH3 forman una unidad funcional conocida como Elemento Regulador N-terminal de c-Src (ERNS). El ERNS (no miristoilado) se caracteriza por la formación de un complejo difuso, donde las regiones intrínsecamente desordenadas: dominios SH4 y Unique mantienen múltiples interacciones débiles con el dominio SH3. La pregunta inevitable es si la naturaleza de este complejo difuso se altera cuando el dominio SH4 está en su forma nativa miristoilada. En esta tesis, se ha realizado la caracterización de la ERNS miristoilada mediante Resonancia Magnética Nuclear y utilizando varias construcciones del ERNS en las formas miristoilada y no miristoilada. Se demuestra que el grupo miristoílo aumenta la concentración local de los dominios SH4 y Unique intrínsecamente desordenados en la proximidad del dominio SH3 favoreciendo cooperativamente las interacciones intramoleculares que definen el complejo difuso. Cuando c- Src no está unido a la membrana, el grupo miristoílo se aloja de manera dinámica en el complejo difuso a través de múltiples sitios de unión en el dominio SH3. Por último, se ha realizado una caracterización preliminar del ERNS en presencia del dominio SH2 adyacente y ésta ha revelado que la región interfaz que conecta los dominios SH3-SH2 también podría ser un componente clave del ERNS.

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Farzinpour, Pouyan. « DYNAMIC TEMPLATING : A NEW PATHWAY FOR THE ASSEMBLY OF LARGE-AREA ARRAYS OF PLASMONIC, MAGNETIC AND SEMICONDUCTOR NANOMATERIALS ». Diss., Temple University Libraries, 2014. http://cdm16002.contentdm.oclc.org/cdm/ref/collection/p245801coll10/id/280637.

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Mechanical Engineering
Ph.D.
Substrate-based nanostructures are of great importance due to their applications in microelectronic devices, chemical sensors, catalysis and photovoltaics. This dissertation describes a novel fabrication technique for the formation of periodic arrays of substrate-based nanoparticles. The prescribed route, referred to as dynamic templating, requires modest levels of instrumentation consisting of a sputter coater, micrometer-scale shadow masks and a tube furnace. The route has broad applicability, having already produced periodic arrays of gold, silver, copper, platinum, nickel, cobalt, germanium and Au-Ag alloys on substrates as diverse as silicon, sapphire, silicon-carbide, and glass. The newly devised method offers large-area, high-throughput capabilities for the fabrication of periodic arrays of sub-micrometer and nanometer-scale structures and overcomes a significant technological barrier to the widespread use of substrate-based templated assembly by eliminating the need for periodic templates having nanoscale features. Because this technique only requires modest levels of instrumentation, researchers are now able to fabricate periodic arrays of nanostructures that would otherwise require advanced fabrication facilities.
Temple University--Theses

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Hardy, M. J. « Integrated surface plasmon generator for application in heat assisted magnetic recording ». Thesis, Queen's University Belfast, 2014. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.676510.

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Presented here is a novel design for a vertical cavity surface emitting laser for supplying heat to a recording medium in a magnetic recording drive, in an attempt to overcome the superparamagnetic limit. Included in the thesis is a discussion of the requirement for a system to focus energy beyond the diffraction limit and onto a recording platter. Plasmonics is introduced as a method to achieve this focusing and the structure to be used in this work is presented. Initial modelling of the structure for a theoretical efficiency and hence feasibility of the design is then conducted. Fabrication of the device is discussed in detail and preliminary characterisation of the device is undertaken.

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Tran, Ngoc Minh. « Applications of nonlinear magneto-photonics at the nanoscale ». Thesis, Le Mans, 2018. http://www.theses.fr/2018LEMA1029/document.

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La génération de seconde harmonique magnétique (mSHG pour magnetic Second Harmonic Generation) est un phénomène physique très sensible apparaissant grâce aux brisures de symétrie aux niveaux des surfaces et interfaces des structures métalliques magnétiques. Elle constitue donc un outil puissant pour explorer ce type d'interfaces et des nanostructures. Dans ce travail, nous nous intéressons aux couplages et interactions entre la mSHG et les ondes électromagnétiques pouvant se propager en surface des matériaux. Un intérêt spécifique est porté sur l’ excitation de (i) plasmon polaritons de surfaces (SPP) dans des films métalliques en structures multicouches, (ii) d'anomalies de diffraction (dîtes de Wood) dans des nanostructures métalliques périodiques. Pour étudier l'influence de l'excitation linéaire et non-linéaire des SPP sur la mSHG, l'intensité du signal réfléchi par génération de seconde harmonique (SH) et le contraste magnétique lié à ce signal ont été mesurés par la technique de l'effet Kerr magnéto-optique transverse (MOKE) en fonction de l'angle d'incidence. Via l'utilisation de sources lasers femtosecondes émettant dans le proche infrarouge, domaine spectral où les variations de la dispersion des SPP et du coefficient d'amortissement sont significatives, nous avons pu distinguer les différentes contributions linéaires et non-linéaires aux processus d'excitation. Ce travail de thèse a ainsi permis de montrer que l’accord de phase entre la mSHG et les ondes électromagnétiques de surface peuvent contribuer très efficacement à l'augmentation des signaux SH et de contraste magnétique associé
Owing to surface and interface sensitivity, the magnetic Second Harmonic Generation (mSHG) represents a useful tool to probe magnetic interfaces and nanostructures. This work investigates the coupling and interaction of the mSHG with electromagnetic waves propagating along the surface. Two types of surface waves have been studied: (i) surface plasmon polaritons (SPP) at surfaces of metallic thin films and multilayers, and (ii) the diffraction anomaly at the surface of periodically arranged metallic nanostructures. To study influence of linear and nonlinear excitation of surface waves on the mSHG, the reflected second harmonic (SH) intensity and the magnetic SH contrast in the transverse magneto-optical geometry were measured as a function of the angle of incidence. The use of different femtosecond light sources in the near-infrared optical range, where the SPP dispersion and damping exhibit significant variations, made it possible to disentangle linear and nonlinear contributions to the excitation of surface waves. In this thesis, it is proven that phase-matching of the mSHG and surface electromagnetic waves can lead to the enhancement of both the SH yield and the nonlinear magneto-optical signal. These results are important for controlling of the nonlinear magneto-optical response and could impact the development of magnetic storage devices, label-free biosensors and nonlinear magneto-optical switches

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Marangoni, Valeria Spolon. « Theranostic nanomaterials applied to the cancer diagnostic and therapy and nanotoxicity studies ». Universidade de São Paulo, 2016. http://www.teses.usp.br/teses/disponiveis/76/76132/tde-21102016-155818/.

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Multifunctional plasmonic nanoparticles have shown extraordinary potential for near infrared photothermal and triggered-therapeutic release treatments of solid tumors. However, the accumulation rate of the nanoparticles in the target tissue, which depends on their capacity to escape the immune system, and the ability to efficiently and accurately track these particles in vivo are still limited. To address these challenges, we have created two different systems. The first one is a multifunctional nanocarrier in which PEG-coated gold nanorods were grouped into natural cell membrane vesicles from lung cancer cell membranes (A549) and loaded with β-lap (CM-β-lap-PEG-AuNRs). Our goal was to develop specific multifunctional systems for cancer treatment by using the antigens and the unique properties of the cancer cell membrane combined with photothermal properties of AuNRs and anticancer activity of β-lap. The results confirmed the assembly of PEG-AuNRs inside the vesicles and the irradiation with NIR laser led to disruption of the vesicles and release of the PEG-AuNRs and β-Lap. In vitro studies revealed an enhanced and synergic cytotoxicity against A549 cancer cells, which can be attributed to the specific cytotoxicity of β-Lap combined with heat generated by laser irradiation of the AuNRs. No cytotoxicity was observed in absence of laser irradiation. In the second system, MRI-active Au nanomatryoshkas were developed. These are Au core-silica layer-Au shell nanoparticles, where Gd(III) ions are encapsulated within the silica layer between the inner core and outer Au layer of the nanoparticle (Gd-NM). This theranostic nanoparticle retains its strong near infrared optical absorption properties, essential for in vivo photothermal cancer therapy, while simultaneously providing increased T1 contrast in MR imaging by concentrating Gd(III) within the nanoparticle. Measurements of Gd-NM revealed a substantially enhanced T1 relaxivity (r1 ~ 17 mM-1 s-1) even at 4.7 T, surpassing conventional Gd(III)-DOTA chelating agents (r1 ~ 4 mM-1 s-1) currently in clinical use. The observed relaxivities are consistent with Solomon-Bloembergen-Morgan (SBM) theory, describing the longer-range interactions between the Gd(III) and protons outside the nanoparticle. These novel multifunctional systems open the door for the development of more efficient nanoplatforms for diagnosis and treatment of cancer.
Nanopartículas plasmônicas multifuncionais têm revelado elevado potencial para fototermia na região (NIR) do infravermelho e liberação controlada de fármacos para o tratamento de tumores sólidos. No entanto, a taxa de acumulação das nanoparticulas no tecido alvo, que depende da capacidade delas de escapar do sistema imunológico, e a habilidade de rastrear de maneira efetiva essas partículas in vivo ainda são limitadas. Para superar essas barreiras, dois sistemas diferentes foram desenvolvidos. O primeiro corresponde a um nanocarreador multifunctional, onde nanobastões de ouro funcionalizados com PEG foram agrupados dentro de vesículas de membranas de células naturais originarias de células cancerígenas de pulmão (A549) conjugadas com β-Lap (CM-β-lap-PEG-AuNRs). Nosso principal objetivo foi desenvolver um sistema multifuncional especifico para tratamento de câncer utilizando os antígenos e propriedades únicas da membrana das células cancerígenas combinados com as propriedades fototérmicas dos AuNRs e a atividade anticancerígena da β-Lap. Os resultados confirmaram o agrupamento dos PEG-AuNRs dentro das CM e irradiação com o laser no NIR levou ao rompimento das vesículas e liberação dos AuNRs e β-Lap. Estudos in vitro revelaram uma elevada e sinérgica citotoxicidade contra células A549, que pode ser atribuída a combinação da especifica toxicidade da β-Lap com o calor gerado pelos AuNRs por meio da irradiação com laser. Nenhuma citotoxicidade significativa foi observada na ausência de irradiação com laser. No segundo sistema, nanomatryoshkas de Au ativas em MRI foram desenvolvidas. Elas consistem em um núcleo de Au, uma camada intersticial de sílica, onde os íons de Gd(III) são encapsulados, e uma camada externa de Au (Gd-NM). Esta nanopartícula teranóstica mantém as propriedades de elevada absorção óptica no NIR, enquanto simultaneamente fornece um elevado contraste T1 em imagem por ressonância magnética por meio da concentração dos íons de Gd(III) dentro da nanoparticula. Medidas de Gd-NM revelaram uma relaxividade elevada (r1 ~ 17 mM-1 s-1 ) a 4,7 T, superando os convencionais agentes quelantes de Gd(III)-DOTA (r1 ~ 4 mM-1 s-1) utilizados clinicamente. As relaxividades observadas são consistentes com a teoria Solomon-Bloembergen-Morgan (SBM), descrevendo as interações de longo alcance entre Gd(III) e prótons de H fora da partícula. Os novos sistemas multifuncionais desenvolvidos abrem oportunidades para o desenvolvimento de nanoplataformas mais eficientes para o diagnóstico e tratamento de câncer.

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Torres, Israel da Silva. « Magnetoplasmons de borda em sistemas bidimensionais : estudo do Helicon de Borda ». Universidade Federal do Amazonas, 2012. http://tede.ufam.edu.br/handle/tede/4542.

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CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
In this work we will make a theoretical investigation over some general properties of edge magnetoplasmos (EMP) - collective quiral excitations which propagates at the edges of a bidimensional solid state plasma (often called bidimensional electronic system- 2DES) under the quantum Hall regime (QHR) with lling factor of = 1(2),with very strong dissipation in the edges, where the Landau levels (LL) intercept the Fermi levels (FL). We will take into account only homogenuous samples, that means, without a consideration of a gate nor an air substrate over the heterostructure; pointed out that the EMP behaviour, especially the wave quality, has a strong dependence on the gate. EMP s were rst reported in the 80 s, and have attracted much attention in the past decade with advent of some new nano-2DES, new experimental methods - as the time- resolved experiments, and nano electronic aplications. Adopting a microscopic model, we could con rm recent works (2010), and we con rmed that even in the strong dissipation regime, here considered, there is still a mode that persists, an edge helicon (EH), with excelent quality - when all other modes are very damped. We also nd new interesting properties of this EH, in fact, we can show that the "window of transparency" of this EH is 10 times bigger then the value so far known from the scienti c literature, its spatial structure was also here accquired with better precision; and it exibits a more smooth behavior if compared to recent articles.
Neste trabalho faremos um estudo teórico acerca de propriedades dos magneto-plasmons de borda (MPB) excitações quirais coletivas e que se propagam nas bordas de um plasma de estado sólido bidimensional (comumente cunhado como um sistema eletrônico bidimensional - SE2D) - sob o regime Hall quântico inteiro (RHQI) com fator de preenchimento = 1(2) e com muito-forte dissipação nas regiões de estados de borda, onde os níveis de Landau (NL) cruzam o nível de Fermi (NF). Serão considerados neste trabalho apenas amostras homogêneas, ou seja, sem a consideração de um gate ou uma camada de ar sobre a heteroestrutura; cujo comportamento dos MPB s, especialmente a qualidade do MPB, tem forte vínculo com propriedades do meio em questão. Os primeiros MPB s foram descobertos na década de 1980, e têm despertado um grande interesse na última década, com o advento de novas nanoestruturas eletrônicas bidimensionais, novos métodos experimentais - como por exemplo os experimentos com tempo-resolvido (time-resolved) e aplicacões diretas em nanoeletrônica. Adotando-se um modelo miscroscópico, pudemos con firmar resultados de trabalhos recentes (2010), e confi rmamos que mesmo no regime de muito-forte dissipação, aqui considerado, ainda há um modo que persiste, um Helicon de Borda (HB), com excelente qualidade - enquanto que todos os outros mo- dos são fortemente amortecidos. Encontramos também novas interessantes propriedades deste HB, em particular, mostramos que "janela de transparência" deste HB é 10 vezes maior do que o valor conhecido na literatura, a estrutura espacial do HB também foi aqui obtida com melhor precisão; e exibe um comportamento mais suave que o apresentado em trabalhos recentes.

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Berger, T., J. Konheiser, A. V. Anikeev, V. V. Prikhodko, P. A. Bagryansky, E. Yu Kolesnikov, E. I. Soldatkina, Yu A. Tsidulko, K. Noack et A. A. Lizunov. « Study of high temperature and high density plasmoids in axially symmetrical magnetic fields ». Forschungszentrum Dresden, 2010. http://nbn-resolving.de/urn:nbn:de:bsz:d120-qucosa-27870.

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Within the framework of an Institutional Partnership of the Alexander von Humboldt Foundation, the Budker Institute of Nuclear Physics Novisibirsk (BINP) and Forschungszentrum Dresden-Rossendorf worked together in a joint project devoted to the research at the coupled GDT-SHIP facility of the BINP with the focus on the study of plasma phenomena within the SHIP mirror section. The project began at July 1st, 2005 and ended on August 30th, 2008. It included work packages of significant theoretical, computational and analyzing investigations. The focus of this final report is on the presentation of results achieved whereas the work that was done is described briefly only. Chapter 2 illustrates the GDT-SHIP facility and describes shortly the planned topics of the SHIP plasma research. Chapter 3 explains the main extensions and modifications of the Integrated Transport Code System (ITCS) which were necessary for the calculations of the fast ion and neutral gas particle fields in SHIP, describes briefly the scheme of computations and presents significant results of pre-calculations from which conclusions were drawn regarding the experimental program of SHIP. In chapter 4, the theoretical and computational investigations of self-organizing processes in two-component plasmas of the GDT-SHIP device are explained and the results hitherto achieved are presented. In chapter 5, significant results of several experiments with moderate and with enhanced plasma parameters are presented and compared with computational results obtained with the ITCS. Preparing neutron measurements which are planned for neutron producing experiments with deuterium injection, Monte Carlo neutron transport calculations with the MCNP code were also carried out. The results are presented. Finally, from the results obtained within the joint research project important conclusions are drawn in chapter 6.

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Chamorro, Coral William. « Microstructure, chemistry and optical properties in ZnO and ZnO-Au nanocomposite thin films grown by DC-reactive magnetron co-sputtering ». Thesis, Université de Lorraine, 2014. http://www.theses.fr/2014LORR0253/document.

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Les matériaux composites peuvent présenter des propriétés qu'aucun des composants individuels ne présente. En outre, à l'échelle du nanomètre les nanocomposites peuvent présenter de nouvelles propriétés par rapport à l'état massif ou à des macrocomposites des mêmes composants en raison d’effets de confinement et d’effets quantiques liés à la taille. Les nanocomposites semi-conducteur/métal sont très intéressants en raison de leurs uniques propriétés catalytiques et opto-électroniques et la possibilité de les ajuster facilement. Ce travail de thèse étudie les interactions spécifiques et les propriétés physiques qui se manifestent dans les films minces de ZnO et nanocomposites ZnO-Au synthétisés par pulvérisation magnétron réactive continue. Premièrement, il est observé qu’il est possible d'ajuster les propriétés microstructurales et optiques des couches de ZnO en réglant les paramètres expérimentaux. La croissance épitaxiale de ZnO sur saphir a été réalisée pour la première fois dans des conditions riches en oxygène sans assistance thermique. En outre, une étude des propriétés optiques met en évidence la relation étroite entre les propriétés optiques et de la chimie des défauts dans les couches minces de ZnO. Un modèle a été proposé pour expliquer la grande dispersion des valeurs de gap rencontrées dans la littérature. Deuxièmement, il a été possible de révéler l'influence profonde de l'incorporation de l'or dans la matrice de ZnO sur des propriétés importantes dans des films nanocomposites. En outre, la présence de défauts donneurs (accepteurs) au sein de la matrice ZnO se permet de réduire (oxyder) les nanoparticules d’or. Ce travail de recherche contribue à une meilleure compréhension des nanocomposites semi-conducteurs/métal et révèle le rôle important de l'état de la matrice semi-conductrice et de la surface des particules pour les propriétés finales du matériau
Composite materials can exhibit properties that none of the individual components show. Moreover, composites at the nanoscale can present new properties compared to the bulk state or to macro-composites due to confinement and quantum size effects. The semiconductor/metal nanocomposites are highly interesting due to their unique catalytic and optoelectronic properties and the possibility to tune them easily. This PhD work gives insight into the specific interactions and resulting physical properties occurring in ZnO and ZnO-Au nanocomposite films grown by reactive DC magnetron sputtering. The results can be summarized in two points: First, it was possible to tune the microstructural and optical properties of ZnO. Epitaxial growth of ZnO onto sapphire was achieved for the first time in O2-rich conditions without thermal assistance. Also, a study of the optical properties highlights the close relationship between the bandgap energy (E_g ) and the defect chemistry in ZnO films. A model was proposed to explain the large scatter of the E_g values reported in the literature. Second, the deep influence of the incorporation of gold into the ZnO matrix on important material properties was revealed. Moreover, the presence of donor (acceptor) defects in the matrix is found to give rise to the reduction (oxidation) of the Au nanoparticles. This research work contributes to a better understanding of semiconductor/metal nanocomposites revealing the key role of the state of the semiconductor matrix

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Dolci, Mathias. « Design of magnetic iron oxide nanoparticle assemblies supported onto gold thin films for SPR biosensor applications ». Thesis, Strasbourg, 2018. http://www.theses.fr/2018STRAE001/document.

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La bio-détection de molécules reposant sur le phénomène de résonnance plasmon permet de détecter des espèces en utilisant les propriétés optiques de films métalliques. L’utilisation de ce type de capteurs nécessite néanmoins l’augmentation de leurs performances afin de détecter des concentrations faibles d’analyte dans des milieux complexes. L’assemblage de nanoparticules d’oxyde de fer sur des substrats d’or, en utilisant des groupements complémentaires spécifiques via la méthode de chimie « click », permet de contrôler leur distribution spatiale à la surface du substrat. Les propriétés magnétiques portées par les nanoparticules sont ainsi étudiées en fonction de leurs distances inter-particules ainsi que de leurs tailles. Par ailleurs, le plasmon de surface du substrat étant directement influencé par l’assemblage des nanoparticules, il sera possible de contrôler la sensibilité du capteur pour étudier la détection de différentes biomolécules impliquées dans des processus biologiques. La présence des nanoparticules augmente les propriétés optiques intrinsèques de la surface du substrat et la géométrie de l’assemblage permet d’augmenter la quantité de biomolécules détectées
Biomolecular detection based on the surface plasmon resonance phenomenon allow detecting species by using the optics properties of metallic thin films. This kind of biosensors require the increase of their performances in order to detect low concentration analyte in complex medium. The assembly of iron oxide nanoparticles on gold substrates by using specific complementary groups via the “click” chemistry technique allows controlling their spatial distribution on the substrate surface. The magnetic properties carried by the nanoparticles are studied as function of their inter-particle distances and their sizes. Moreover, the surface plasmon of the substrate is directly influenced by the nanoparticle assembly and the control of the sensor sensitivity will be possible in order to study the detection of different biomolecules implies in biological processes. The presence of nanoparticles increases the intrinsic optical properties at the substrate surface and the geometry of the assembly allow increasing the number of biomolecules detected

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Sokolov, A. E., V. N. Zabluda, S. G. Ovchinnikov, B. A. Knyazev, V. V. Gerasimov, Yu L. Michlin, E. A. Veshnyakova, Y. V. Zubavichus et A. M. Kalsin. « Magnetooptics in Gold and Silver NanoSizes Low-Dimensional Objects ». Thesis, Sumy State University, 2013. http://essuir.sumdu.edu.ua/handle/123456789/35344.

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The spectra of optical absorption and of magnetic circular dichroism (MCD) have been measured in the 350–1150 nm wavelength range for a set of colloidal solutions containing Au and Ag nanoparticles. The average size of Au nanoparticles was 6 nm and having thiolate coatings with different degrees of chirality. (The average size of Ag nanoparticles was 14 nm and having citrate coatings) The form of absorption and MCD spectra suggests the dipole character of interband transitions involving the 5d–6(sp) for Au orbitals and 4d–5(sp) for Ag orbitals. The absence (within the experimental error) of the MCD spectra dependence on the coating type rules out the hypothesis on the orbital nature of the observed magnetism. We argue that the spin polarization plays the dominant role in the magnetism both for Au and Ag nanoparticles. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/35344

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Berger, T., J. Konheiser, A. V. Anikeev, V. V. Prikhodko, P. A. Bagryansky, E. Yu Kolesnikov, E. I. Soldatkina, Yu A. Tsidulko, K. Noack et A. A. Lizunov. « Study of high temperature and high density plasmoids in axially symmetrical magnetic fields ». Forschungszentrum Dresden-Rossendorf, 2009. https://hzdr.qucosa.de/id/qucosa%3A21614.

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Within the framework of an Institutional Partnership of the Alexander von Humboldt Foundation, the Budker Institute of Nuclear Physics Novisibirsk (BINP) and Forschungszentrum Dresden-Rossendorf worked together in a joint project devoted to the research at the coupled GDT-SHIP facility of the BINP with the focus on the study of plasma phenomena within the SHIP mirror section. The project began at July 1st, 2005 and ended on August 30th, 2008. It included work packages of significant theoretical, computational and analyzing investigations. The focus of this final report is on the presentation of results achieved whereas the work that was done is described briefly only. Chapter 2 illustrates the GDT-SHIP facility and describes shortly the planned topics of the SHIP plasma research. Chapter 3 explains the main extensions and modifications of the Integrated Transport Code System (ITCS) which were necessary for the calculations of the fast ion and neutral gas particle fields in SHIP, describes briefly the scheme of computations and presents significant results of pre-calculations from which conclusions were drawn regarding the experimental program of SHIP. In chapter 4, the theoretical and computational investigations of self-organizing processes in two-component plasmas of the GDT-SHIP device are explained and the results hitherto achieved are presented. In chapter 5, significant results of several experiments with moderate and with enhanced plasma parameters are presented and compared with computational results obtained with the ITCS. Preparing neutron measurements which are planned for neutron producing experiments with deuterium injection, Monte Carlo neutron transport calculations with the MCNP code were also carried out. The results are presented. Finally, from the results obtained within the joint research project important conclusions are drawn in chapter 6.

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Wang, Mengjia. « Spin-orbit interactions for steering Bloch surface waves with the optical magnetic field and for locally controlling light polarization by swirling surface plasmons ». Thesis, Bourgogne Franche-Comté, 2019. http://www.theses.fr/2019UBFCD013/document.

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Ma thèse est consacrée aux nouveaux phénomènes nano-optiques et aux dispositifs basés sur l'interaction spin-orbite de la lumière (SOI). Tout d'abord, il a été démontré un SOI uniquement piloté par le champ magnétique de la lumière permettant de diriger avec précision les ondes de surface de Bloch, offrant ainsi une nouvelle manifestation du champ magnétique optique. Ensuite, nous avons proposé et démontré le concept de nano-antenne plasmonique hélicoïdale à ondes progressives (TW-HPA), c’est-à-dire un fil hélicoïdal en or étroit alimenté optiquement par une nano-antenne dipolaire dans une configuration « end-firing ». Une telle nano-antenne a été démontrée comme la première optique de polarisation sublongueur d’onde. L’agencement de TW-HPAs à l’échelle de quelques microns a permis de convertir « à la carte » un faisceau polarisé linéairement en une distribution de faisceaux directifs présentant des polarisations différentes définies de façon déterministe par la géométrie et les dimensions des nano-antennes. Par le biais d’un couplage en champ proche de quatre nano-antennes à hélicités opposées, nous avons obtenus une optique sublongueur d’onde permettant un degré de liberté dans le contrôle de la polarisation qui est interdit avec les composants et méthodes classiques basées sur l’exploitation de matériaux biréfringents ou dichroïques, ou de métamatériaux imitant ces propriétés
My thesis is devoted to novel nano-optical phenomena and devices based on spin-orbit interaction (SOI) of light. First, magnetic spin-locking, i.e., an SOI solely driven by the magnetic field of light, is demonstrated with Bloch surface waves. It provides a new manifestation of the magnetic light field. Then, we propose and demonstrate the concept of traveling-wave plasmonic helical antenna (TW-HPA), consisting of a narrow helical gold-coated wire non-radiatively fed with a dipolar nano-antenna. By swirling surface plasmons, the TW-HPA combines subwavelength illumination and polarization transformation. The TW-HPA is demonstrated to radiate on the subwavelength scale almost perfectly circularly polarized optical waves upon illumination with linearly polarized light. With this subwavelength plasmonic antenna, we developed strongly integrated arrays of point-light emissions of opposite handedness and tunable intensities. Finally, by coupling two couples of TW-HPAs of opposite handedness, we obtained new polarization properties so far unattainable

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AHMAD, ALI. « Study of impulsive magnetic reconnection due to resistive tearing mode with the effect of viscosity and dynamic flow in fusion plasmas ». Kyoto University, 2015. http://hdl.handle.net/2433/199415.

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Machacek, A. C. « Extending the validity range of the linear, fluid description of parametric instabilities in laser produced plasma ». Thesis, University of Oxford, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.326108.

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Nunez, Eroles Marc. « Nanogravure et caractérisation structurale et électronique de rubans de graphène cristallins ». Thesis, Toulouse 3, 2015. http://www.theses.fr/2015TOU30201/document.

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Les principaux objectifs de cette thèse sont la fabrication et la caractérisation structurale à haute résolution de nanorubans de graphène à bords atomiquement lisses ainsi que leur intégration dans des composants et l'étude du transport électronique. En premier lieu, nous montrons que des nanorubans de graphène cristallins de largeur inférieure à 100 nm et avec des qualités structurales supérieures l'état de l'art peuvent être découpé par un faisceau électronique focalisé d'énergie modérée en présence d'oxygène. Les caractéristiques des rubans obtenus sont également supérieures à l'approche précédente utilisant la vapeur d'eau. Dans un deuxième temps, la structure des nanorubans est caractérisée jusqu'à l'échelle atomique par microscopie électronique en transmission corrigée des aberrations sphériques. Nous montrons que la cristallinité des nanorubans, tant en leur centre que le long des bords de découpe, est préservée. Les performances de notre approche atteignent l'état de l'art et sa reproductibilité permet de fabriquer des rubans longs de plusieurs centaines de nanomètres mais de largeur aussi fine que 16 nm. Ensuite, nous avons transposé la découpe de nanoruban suspendus à une configuration partiellement suspendue sur substrat SiO2/Si permettant de les intégrer dans des composants adaptés aux mesures de transport électronique à basse température et sous champ magnétique. Le transport électronique dans les rubans contactés de 60 x 300 nm présente un gap et des oscillations en balayage de grille arrière qui sont en accord avec un mécanisme de blocage de Coulomb dans un domaine de taille de l'ordre de la taille du ruban. Si ces résultats montrent la persistance de barrières tunnel, ses bords semblent de qualité suffisante pour ne pas induire de confinement supplémentaire. Au-delà des composants mésoscopiques, notre méthode de fabrication des rubans par gravure électronique sous oxygène ouvre des perspectives dans deux domaines en émergence. Elle est compatible avec l'ultravide et parfaitement adaptée au développement d'une technologie atomique à base de graphène. Une caractérisation de la contamination du graphène ainsi qu'une caractérisation électrique de dispositifs de graphène qui a été fait par microscopie à effet tunnel multisonde en ultra vide. Enfin, les rubans de graphène que nous produisons ont les dimensions et qualités structurales requises pour observer un comportement plasmonique du graphène dans le visible et ainsi interagir avec des structures plasmoniques métalliques. Ce couplage a été examiné en étudiant le signal Raman du graphène au voisinage de colloïdes d'or
The main objectives of this thesis are the fabrication and high-resolution structural characterisation of graphene nanoribbons with atomically smooth edges as well as their device integration and electronic transport study. In first place, we show that crystalline graphene nanoribbons with width under 100 nm and structural properties better than the state of the art can be patterned by a focused electron beam in presence of oxygen. The structural characteristics of the ribbons are also better than the old process using water vapour. Secondly, nanoribbons structure is characterized down to the atomic scale by spherical aberration corrected transmission electron microscopy. We show that the nanoribbons crystallinity, of the centre as well as along the cut edges, is preserved. The performance of our process reaches the state of the art and its reproducibility allows to produce ribbons with length of hundreds of nanometer but as narrow as 16 nm. After that, we have transposed the suspended nanoribbon etching to a partially suspended configuration on a SiO2/Si substrate allowing the integration in devices suitable for electronic transport measurements at low temperature and under magnetic field. The electronic transport in contacted ribbons of 60x300 nm shows a gap and oscillations on backgate scanning measurements that are in agreement with a Coulomb blockade mechanism with dot sizes in the range of the ribbon surface. Even though those results show the persistence of tunnel barriers, the edges quality look good enough to avoid additional confinement. Other than mesoscopic devices, our ribbon fabrication process by electronic beam under oxygen atmosphere opens perspectives in two emergent fields. The process is ultra high vacuum compatible and perfectly adapted to the development of an atomic graphene based technology. A characterisation of contaminants of graphene samples as well as electrical characterisation of graphene devices has been performed in a multiprobe scanning tunnelling microscope in ultra high vacuum. Finally, our graphene nanoribbons have the right dimensions and structural qualities required for the observation of plasmonic behaviour of graphene in visible light and so interact with metallic plasmonic structures. This coupling has been analysed by studying the Raman signal of graphene at the close environment of gold colloids

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AHMAD, ALI. « 核融合プラズマにおける粘性と動的流れの影響を受けた抵抗性ティアリングモードによる突発的磁気リコネクションに関する研究 ». Kyoto University, 2015. http://hdl.handle.net/2433/199546.

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Beneš, Adam. « Plazmonické antény pro vysoké vlnové délky ». Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2021. http://www.nusl.cz/ntk/nusl-443226.

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Tato diplomová práce se zabývá vlastnostmi plazmonických antén v oblasti vysokých vlnových délek. Důraz je kladen na popis rezonančních vlastností jednotlivých antén i antén uspořádaných do periodických polí. Těžiště práce spočívá v počítačovém modelování navýšení magnetického pole v blízkosti antén, které lze využít ve vysokofrekvenční elektronové paramagnetické rezonanci (HFEPR) k zesílení měřeného signálu. Autor se zabývá kvantifikací zesílení v anténách s odlišnou geometrií a navrhuje i geometrii vlastní. Značná část práce se také věnuje snaze rozlišit příspěvky k navýšení magnetického pole od různých zdrojů při měření HFEPR v uspořádání s dvojitou transmisí záření.

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Johansson, Malin. « Investigation of hPin1 mediated phosphorylation dependency in degradation control of c-Myc oncoprotein ». Thesis, Linköpings universitet, Molekylär Bioteknik, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-92718.

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Cancer is the main cause of death in economically developed countries and the second leading cause of death in developing countries. Along with today’s knowledge that more than two hundred different diseases lie in the category of this prognosis there is an urge for more detailed and case-specific treatments to replace the dramatic actions of available radiation- and chemotherapy, which in many cases do not make a difference between healthy and cancer cells. The transcription factor and onco-protein c-Myc has, after being extensively studied during the past decades, become a prognostic marker for almost all cancer forms known. Still, many questions remain regarding how c-Myc interacts with its many different target proteins involved in cell-cycle regulation, proliferation and apoptosis. Current cell biology states that one of the regulating proteins, hPin1, interacts with c-Myc in a phosphorylation-dependent manner which appears to direct the correct timing of c-Myc activation and degradation through the ubiquitin/proteasome-pathway. The critical phosphorylation sites, T58 and S62, are located in the Myc-Box-I (MBI) region, a highly conserved sequence strongly coupled to aggressive tumourigenesis by hotspot mutations. Interestingly, preliminary results in the Sunnerhagen group suggested that MBI alone did not bind hPin1, suggesting hPin1 targeting a site distal from the residues to be phosphorylated. In this thesis, results from Surface Plasmon Resonance (SPR) and Nuclear Magnetic Resonance (NMR) show that the docking WW-domain of hPin1 binds unphosphorylated c-Myc at a region distal from the phosphorylation site, including residues 13-34. Furthermore, SPR experiments revealed that hPin1 binds unphosphorylated c-Myc with apparently greater affinity and with much slower kinetics than phosphorylated c-Myc. Thus, hPin1 recognition and interaction with c-Myc appears not to be dependent on phosphorylation of c-Myc prior binding. The newly identified binding region of c-Myc, located N-terminal of MBI, may further increase the understanding of protein degradation control and c-Myc function. The studies presented in this thesis provide a brick in the puzzle of c-Myc and hPin1 coupled oncogenesis for further development of new therapeutic strategies.

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Brannon, Mary Katherine. « Binding properties of adaptor proteins Tollip and Tom1 ». Thesis, Virginia Tech, 2015. http://hdl.handle.net/10919/73814.

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Adaptor proteins, like Tollip and Tom1, facilitate cellular cargo sorting through their ubiquitin-binding domains. Tollip and Tom1 bind to each other through their TBD and GAT domains, respectively, whereas Tollip interacts with phosphatidylinositol-3-phosphate (PtdIns(3)P)-containing endosomal membranes. Tom1 and Tollip interaction and association with endosomes is proposed to be involved in the lysosomal degradation of polyubiquitinated cargo. Through cellular, biochemical, and biophysical techniques, we have further characterized the association of Tom1 with Tollip. Mutations in the binding interface of the Tom1 GAT and Tollip TBD complex leads to a subcellular mis-localization of both proteins, indicating that Tom1 may serve to direct Tollip to specific cellular pathways. It was determined that Tom1 inhibits the binding of Tollip to PtdIns(3)P and inhibition was reversed when mutations in the binding interface of the Tom1 GAT and Tollip TBD were present. Furthermore, it was established that, upon the binding of Tollip TBD to Tom1 GAT, ubiquitin is inhibited from binding to Tom1 GAT. It was also demonstrated that Tom1 GAT, but not Tollip TBD, can weakly bind to PtdIns(3)P. Consequently, we propose that association of Tom1 may serve to direct Tollip for involvement in specific cell signaling pathways. Gaining insight into the function of Tom1 and Tollip may lead to their use as therapeutic targets for increasing the efficiency of cargo trafficking and also for patients recovering from various cardiac injuries.
Master of Science

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De, Masi Deborah. « Nanoparticules bimétalliques combinant propriétés catalytiques et physiques pour la valorisation du CO2 et de la biomasse ». Thesis, Toulouse, INSA, 2019. http://www.theses.fr/2019ISAT0024.

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Les réactions réalisées en catalyse hétérogène nécessitent des températures et pressions élevées. Une façon originale pour améliorer ces conditions de réaction est de générer des températures élevées directement à la surface des catalyseurs par des stimuli physiques (magnétiques ou plasmoniques). L’objectif de cette thèse a été la mise en place de la synthèse de nanoparticules complexes combinant des propriétés physiques et des propriétés catalytiques. Ainsi, deux types de nanoparticules ont été synthétisées, des nanoparticules de fer-nickel pour le chauffage magnétique et des nanoparticules bimétalliques or-ruthénium pour le chauffage plasmonique. Dans le contexte actuel de développement durable et de stockage des énergies renouvelables, nous avons étudié deux réactions catalytiques : la réaction de Sabatier et l’hydrodésoxygénation de molécules plateformes issues de la biomasse lignocellulosique. Sous champ magnétique, la génération au voisinage des nanoparticules de fer-nickel de très hautes températures a permis de créer un environnement hétérogène à la surface des nanoparticules. Ainsi, la conversion totale du furfural et de l’hydroxyméthylfurfural en biocarburants (le méthylfurane et le diméthylfurane) a pu être réalisée en solution dans des conditions très douces. Les propriétés de chauffe et les propriétés catalytiques des nanoparticules de fer-nickel ont permis d’activer la réaction de Sabatier, et d’atteindre pour la première fois des rendements en méthane de 100 %. Dans la même optique, les propriétés plasmoniques et catalytiques des nanoparticules d’or-ruthénium ont été étudiées pour la réaction de Sabatier. Un couplage entre chauffage classique et irradiation lumineuse a permis de mettre en évidence un effet synergique entre le ruthénium et l’or pour l’activation de la réaction
Heterogeneous catalytic reactions require often very harsh conditions, i.e. high temperature and high pressure in the overall system. An original way to lower these reaction conditions consists in generating a local heating directly at the surface of the catalysts by the means of physical stimuli (magnetic or plasmonics). However, up to now, the catalytic sites and the heating agents were spatially separated, reducing the efficiency of the heat transfer. The aim of this thesis is thus to elaborate complex bimetallic nanoparticles combining physical properties and catalytic properties in the very same object. Two types of nanoparticles have been synthesized, iron-nickel nanoparticles for magnetic heating and gold-ruthenium nanoparticles for plasmonic heating. In the current context of sustainable development and storage of renewable energies, we studied two catalytic reactions: the Sabatier reaction, to valorize CO2 gas and the hydrodeoxygenation of platforms molecules from lignocellulosic biomass to yield biofuel. Under alternating magnetic field, iron-nickel nanoparticles generate high temperatures creating a heterogeneous environment at their surface. Thanks to these peculiar conditions, the furfural and the hydroxymethylfurfural could be totally converted, in liquid phase, into biofuels (methylfurane and dimethylfurane) under mild conditions. Moreover, heat properties of iron-nickel nanoparticles combining with their catalytic properties have made possible the total conversion of carbon dioxide into methane. Similarly, plasmonic and catalytic properties of gold-ruthenium nanoparticles were studied for the Sabatier reaction. By coupling classical heating and light irradiation a synergetic effect between ruthenium and gold was observed leading to the efficient activation of the reaction

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Ernandes, Cyrine. « Manipuler l'émission et l'absorption de transitions dipolaires magnétiques par l'utilisation de nano-antennes optiques ». Electronic Thesis or Diss., Sorbonne université, 2019. http://www.theses.fr/2019SORUS091.

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Au cours des dernières années, les progrès technologiques dans le domaine de la nanophotonique ont permis le développement des nanostructures optiques. Ces dernières possèdent la particularité de modifier l'émission lumineuse de nanoémetteurs quantiques .Cependant, l’interaction lumière-matière est considérée comme étant véhiculée par le champ électrique. Les études se sont alors concentrées sur le contrôle et la modification des propriétés d'excitation et d'émission des transitions dipolaires électriques.Récemment, il a été décrit qu’il existe dans la nature des nanoémetteurs possédant des transitions magnétiques détectables : ces nanoémetteurs sont les ions lanthanides.Les nanostructures optiques développant des résonances magnétiques pourraient alors modifier l’émission et l’excitation de transitions dipolaires magnétiques, de la même manière que leurs homologues électriques.Dernièrement , il a été démontré théoriquement que certain type de nanostructure, peuvent renforcer le champ magnétique optique par deux ordres de grandeur et qu’une fois couplé à un dipôle magnétique, ils peuvent augmenter fortement la fluorescence des transitions magnétiques comme celle qui que se trouve dans les ions de lanthanide.Une étude publiée dans Physical review letters, a rapporté qu’il était aussi possible d’étudier l’excitation de transitions dipolaires magnétiques.L’objectif de ma thèse a donc été d’utiliser certaines nanostructures ayant des affinités particulières avec le champ magnétique afin d’étudier et de manipuler l’émission et l'absorbption de transitions dipolaires magnétiques
During the last years, technological progresses in the field of nanophotonic have allowed the development of optical nanostructures to manipulate the emission of fluorescent nanoemitters . However, light-matter interactions are usually considered to be mediated by the optical electric field only, discarding the magnetic side of it. Indeed, most of the past studies have been only studying the modification of the excitation or emission properties of electric dipole transitions. Recently, it was demonstrated that magnetic dipole could also be found in lanthanide ions. It was also shown that by changing the magnetic local density of states near these ions, the emission fluorescent of the magnetic transitions could be enhanced or decreased with respect to their electric counterpart. In here, we demonstrate experimentally, in perfect agreement with numerical simulations, the manipulation of magnetic and electric dipolar transitions by means of plasmonic cavities. Using a near-field scanning optical microscope (NSOM), we bring in close proximity a nanoparticle doped with trivalent europium to plasmonic cavities of different sizes made of aluminum , allowing perfect control over the interactions between the emitter and the nanostructures. In this study, we show both an increase and decrease of electric and magnetic signal from the particle, and we also display the spatial distribution of both the electric and magnetic radiative local density of state at the surface of the cavities.Therefore, this work pave the way to the understanding of ‘magnetic light’ and matter interactions

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Robertson, Ian Butler. « An investigation into the molecular mechanism of the fibrillin1-LTBP1 interaction ». Thesis, University of Oxford, 2012. http://ora.ox.ac.uk/objects/uuid:e154e0a2-c0cb-42bd-8b90-7a13460700c0.

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Many studies have demonstrated a connection between the fibrillin matrix and TGFβ signalling, but at present the mechanistic basis for this link is unclear. An interaction between the C-terminus of Latent TGFβ Binding Protein 1 (LTBP1) and the N-terminus of fibrillin1 has previously been identified, and may have the potential to directly link the fibrillin matrix to TGFβ signalling. To investigate the structural basis for this interaction, several multi-domain fragments of fibrillin1 and LTBP1 were expressed prokaryotically and refolded in vitro. After initial characterisation to confirm folding, the structure, dynamics, and interdomain interactions of these fragments were investigated in more detail using NMR techniques. Domains in both LTBP1 and fibrillin1 appear to demonstrate folds consistent with homologous structures, and while the LTBP1 C-terminal cbEGF14-TB3-EGF3-cbEGF15 region contains many flexible linkers and few interdomain interactions, the fibrillin1 EGF2-EGF3-hyb1-cbEGF1 region appears rigid, with interfaces forming between all domains present. SPR studies were used to demonstrate binding between distinct LTBP1 and fibrillin fragments, suggesting interactions between multiple domains are involved in the LTBP1-fibrillin1 interaction. The binding sites involved were then mapped to specific residues using HSQC titration studies, and structural models for the LTBP1-fibrillin1 interaction were generated based on these data. Predictions from these models were used to target residues for site-directed mutagenesis, based on their potential involvement in salt bridges, and when certain residues were replaced with those of opposite charge, reductions in binding could be seen in the SPR assay. These key residues were consistent with a particular model of the LTBP1-fibrillin1 interaction, as derived from the HSQC titration data. The conservation of potential binding site residues through deuterostome evolution also supports an important biological role for the LTBP-fibrillin interaction.

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Magné, Damien. « Synthèse et structure électronique de phases MAX et MXènes ». Thesis, Poitiers, 2016. http://www.theses.fr/2016POIT2284/document.

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Les objectifs de ce travail sont d'une part d'étudier la structure électronique de carbures de titane bidimensionnels appartenant à la famille des MXènes, et d'autre part de synthétiser des films minces pour caractériser certaines de leurs propriétés. L'étude de la structure électronique a été réalisée sur le système Ti3C2T2 avec une attention particulière portée aux groupements de surface T (T=OH, F ou O) en comparant les résultats obtenus par spectroscopie de perte d'énergie des électrons à ceux des calculs ab initio. Cette étude, portée à la fois sur les excitations du gaz d'électrons de valence et des électrons de coeur, a permis de mettre en évidence la localisation des groupements de surface, ainsi que leur influence sur la structure électronique du MXene. La comparaison des simulations et des spectres expérimentaux a également permis de caractériser la nature chimique des groupements de surface. Enfin, la limite d'une telle étude est discutée en considérant les phénomènes d'irradiation responsables de la perte d'atomes d'hydrogène. La synthèse d'échantillons modèles nécessite la synthèse préalable d'un film mince de phase MAX précurseur pour le MXene : nous avons choisi la phase Ti2AlC, précurseur de Ti2C. La synthèse de Ti2AlC a été réalisée par recuit ex-situ de systèmes multicouches déposés à température ambiante. Les films ont été caractérisés par diffraction des rayons X et microscopie électronique en transmission. Au-delà de l'obtention d'un film mince de Ti2AlC texturé, cette étude a permis de montrer que la phase recherchée était obtenue via des mécanismes d'interdiffusions induisant la formation d'une solution solide métastable vers 400°C qui se transforme en phase MAX vers 600°C. Enfin, l'application de ce procédé à la phase V2AlC a permis de montrer l'importance de l'orientation de la phase initiale pour l'obtention d'un film mince texturé
The aim of this work is at first to study the electronic structure of bidimensional titanium carbide systems, belonging to the MXene family and also to synthesize thin films of such new materials to characterize their properties. The study of the electronic structure has been performed for the Ti3C2T2 MXene with a special attention to the T surface groups by using a combination of electron energy loss spectroscopy and ab initio calculations. This study, focused on both valence and core electrons excitations, enabled the identification of the surface group localization, their influence on the MXene electronic structure as well as their chemical nature. The limits of our TEM-based study is also discussed in view of irradiation phenomena which induce the loss of hydrogen atoms. The synthesis of a MXene thin film requires, beforehand, that of a MAX phase thin film: we opted for Ti2AlC, the precursor for the Ti2C MXene. The MAX phase thin film synthesis was carried out by ex-situ annealing of a multilayer layers. X-ray diffraction experiments and cross-sectional transmission electron microscopy observations show that a highly textured Ti2AlC thin film is obtained above 600°C after the formation, at 400°C, of a metastable solid solution. Finally, by using the same process for V2AlC, we demonstrate that the initial phase orientation plays a key role for the texture of the thin film so obtained

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SHEN, CHUN-HAO, et 沈俊豪. « The Magneto-plasmonic Effect of Amorphous Carbon/Gold Multilayer ». Thesis, 2016. http://ndltd.ncl.edu.tw/handle/03216126292059305770.

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碩士
國立屏東大學
應用物理系碩士班
104
The gold nanoparticles have been accepted as great potential plasmonic material due to its low impedance property. Recently, a research reported an applied plasmonic mode which is magneto plasmonic on colloidal gold nanoparticles detected by magnetic circular dichroism spectroscopy. In terms of carbonaceous material, interface of carbon has rich phenomena. Compared to silicon only sp3 orbit, amorphous carbon has both sp3 and sp2 orbit. To modulate the thin film property of carbon-based material just needs to modify its orbital configurations. Therefore, this study prepared amorphous carbon/gold discontinuous multilayers by RF Magnetron Sputtering and measured magneto-plasmonic by the Magnetic Circular Dichroism. Compare C/Au and Si/Au discontinuous multilayers in same thickness, C/Au has strong MCD signals relatively. It’s probable that lone pair of carbon sp2 orbits occurs charge-transfer at the interface between carbon and gold. This result may promote the research about combining of carbon and gold.

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LIN, EN-PING, et 林恩平. « Enhanced Magneto-optical Kerr Effects on Surface Plasmonic Grating ». Thesis, 2012. http://ndltd.ncl.edu.tw/handle/61801994581803442494.

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碩士
國立清華大學
光電工程研究所
101
Surface plasmonic polariton (SPP) for the use of bio-sensing has been widely studied. In this thesis, SPP combined with magneto-optical effect is used for enhancing the sensitivity of the device. We designed a sub-wavelength grating structure made from Au/Fe/Au composite layers simultaneously achieving the advantage of low optical absorption of gold and high permeability characteristics of iron. The grating structure used in this experiment not only can be able to remove the prism which the conventional surface plasmon sensor requires but also satisfy the conditions of surface plasmon coupling in normal incident situation. Unlike the general prism setup that the SPP is coupled from the back side of structure, the grating coupler can be able to excite the SPP wave on the top of the grating and reduced the absorption of surface plasmon from ferromagnetic material. Based on these characteristics, the structure designed in this thesis can increase the thickness of ferromagnetic material to improve the magnetization without inducing more absorption and enhanced the magneto-optical signal significantly. The experimental results agree well with the analysis of magneto-optical signal enhanced by SPP near the surface plasmon resonance wavelength. The estimated sensitivity of our structure is 1.7 times larger than the grating coupler without including the magneto-optical effect. And the sensitivity of Au/Fe/Au SPP grating coupler designed in our experiment is 4 times larger than the Au/Fe/Au SPP sensor through prism couplers.

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(9026657), Bradlee K. Beauchamp. « Synthetic Ferrimagnets and Magneto-Plasmonic Structures for Ultrafast Magnetization Switching ». Thesis, 2020.

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The response time of magnetization switching in current spintronic devices is limited to nanosecond timescales due to the precessional motion of the magnetization during reversal. To overcome this limit two routes of investigation leading to novel recording and logic devices are considered in this thesis: 1) Magnetic tunnel junction structures where the recording and reference layers are replaced by synthetic ferrimagnets and switching is induced by spin transfer torque and 2) Hybrid magneto-photonic devices where switching is induced by plasmon-enhanced all-optical switching. To circumvent limitations of the materials and magnetic properties of CoFeB, the most utilized alloy in spintronics, hcp-CoCrPt, a material that exhibits superior perpendicular anisotropy and thermal stability, is chosen as the ferromagnetic electrode in this work. Whereas actual devices based on the two schemes aforementioned are still in the process of being fabricated, through collaborative work with our international collaborators, this thesis describes fundamental magnetic and structural characterization needed for the realization of said ultrafast switching devices. The magnetic switching behavior of CoCrPt-Ru-CoCrPt synthetic ferrimagnets with perpendicular magnetic anisotropy have been studied in the temperature range from 2K to 300K. It was found that two sets of magnetic transitions occur in the CoCrPt-Ru-CoCrPt ferrimagnet systems studied. The first set exhibits three magnetization states in the 50K – 370K range, whereas the second involves only two states in the 2K and 50K range. The magnetic hysteresis curves of the synthetic ferrimagnet are assessed using an energy diagram technique which accurately describes the competition between interlayer exchange coupling energy, Zeeman energy, and anisotropy energy in the system. This energy diagram analysis is then used to predict the changes in the magnetic hysteresis curves of the synthetic ferrimagnet from 200K to 370K. This represents the potential operation temperature extrema that a synthetic ferrimagnet could be expected to operate at, were it to be utilized as a free layer in a memory or sensor spintronic device in the device configuration described in this dissertation.

Circularly polarized fs laser pulses generate large opto-magnetic fields in magnetic materials, through the inverse Faraday effect. These fields are attributed to be largely responsible for achieving ultrafast all-optical magnetization switching (AOS). All experimental demonstrations of AOS thus far have been realized on thin films over micron-sized irradiated regions. To achieve magnetization switching speeds in the ps and potentially fs time regimes, this work proposes the use of surface plasmon resonances at the interface of hybrid magneto-photonic heterostructures. In addition to the ability of plasmon resonances to confine light in the nm scale, the resonant excitation can largely enhance induced opto-magnetic fields in perpendicular magnetic anisotropy materials. This requires strong spin-photon coupling between the plasmonic and the magnetic materials, which thus requires the minimization of seed layers used for growth of the magnetic layer. This work reports on the development of ultrathin (1 nm thick) interlayers to control the growth orientation of hcp-Co alloys grown on the refractory plasmonic material, TiN, to align the magnetic axis out-of-plane. CoCrPtTa seed layers down to 1 nm were developed to seed the growth of CoCrPt, and the dependence of the quality of the CoCrPt is investigated as Ta composition is varied in the seed layer. Whereas bismuth iron garnet (BIG) meets the magneto-optical requirements for a hybrid magneto-photonic material, its magnetic and structural properties are highly sensitive to the Bi:Fe ratio and must be grown epitaxially on single crystalline substrates. Therefore, in this work we have investigated alternative materials that offer superior magnetic properties and are amenable to growth on inexpensive substrates. Opto-magnetic field enhancements up to 2.6x in Co-ferrite magneto-photonic heterostructures have been obtained via finite element analysis modelling. Alternative materials for plasmon-enhanced all-optical switching such as Co/Pd multilayers have also been investigated. Successful growth of Co/Pd multilayers on TiN using ultrathin Ti interlayers has been achieved.

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Thèses sur le sujet « Magneto plasmonic »

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