Download or read book Near infrared Plasmonics with Vacancy Doped Semiconductor Nanocrystals written by Ilka Kriegel and published by . This book was released on 2013 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Near Infrared Localized Surface Plasmon Resonances Arising from Free Carriers in Doped Quantum Dots written by and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Quantum confinement of electronic wavefunctions in semiconductor quantum dots (QDs) yields discrete atom-like and tunable electronic levels, thereby allowing the engineering of excitation and emission spectra. Metal nanoparticles, on the other hand, display strong resonant interactions with light from localized surface plasmon resonance (LSPR) oscillations of free carriers, resulting in enhanced and geometrically tunable absorption and scattering resonances. The complementary attributes of these nanostructures lends strong interest toward integration into hybrid nanostructures to explore enhanced properties or the emergence of unique attributes arising from their interaction. However, the physicochemical interface between the two components can be limiting for energy transfer and synergistic coupling within such a hybrid nanostructure. Therefore, it is advantageous to realize both attributes, i.e., LSPRs and quantum confinement within the same nanostructure. Here, we describe well-defined LSPRs arising from p-type carriers in vacancy-doped semiconductor quantum dots. This opens up possibilities for light harvesting, non-linear optics, optical sensing and manipulation of solid-state processes in single nanocrystals.

Download or read book Plasmonic Materials and Metastructures written by Shangjr Gwo and published by Elsevier. This book was released on 2023-09-11 with total page 347 pages. Available in PDF, EPUB and Kindle. Book excerpt: Plasmonic Materials and Metastructures: Fundamentals, Current Status, and Perspectives reviews the current status and emerging trends in the development of conventional and alternative plasmonic materials. Sections cover fundamentals and emerging trends of plasmonic materials development, including synthesis strategies (chemical and physical) and optical characterization techniques. Next, the book addresses fundamentals, properties, remaining barriers for commercial translation, and the latest advances and opportunities for conventional noble metal plasmonic materials. Fundamentals and advances for alternative plasmonic materials are also reviewed, including two-dimensional hybrid materials composed of graphene, monolayer transition metal dichalcogenides, boron nitride, etc. In addition, other sections cover applications of plasmonic metastructures enabled by plasmonic materials with improved material properties and newly discovered functionalities. Applications reviewed include quantum plasmonics, topological plasmonics, chiral plasmonics, nanolasers, imaging (metalens), active, and integrated technologies. Provides an overview of materials properties, characterization and fabrication techniques for plasmonic metastructured materials Includes key concepts and advances for a wide range of metastructured materials, including metamaterials, metasurfaces and epsilon-near-zero plasmonic metastructures Discusses emerging applications and barriers to commercial translation for quantum plasmonics, topological plasmonics, nanolasers, imaging and integrated technologies

Download or read book Ultrafast Dynamics In Molecules Nanostructures And Interfaces Selected Lectures Presented At Symposium On Ultrafast Dynamics Of The 7th International Conference On Materials For Advanced Technologies written by Guglielmo Lanzani and published by World Scientific. This book was released on 2014-01-22 with total page 304 pages. Available in PDF, EPUB and Kindle. Book excerpt: Primary events in natural systems or devices occur on extremely short time scales, and yet determine in many cases the final performance or output. For this reason research in ultrafast science is of primary importance and impact in both fundamental research as well as its applications. This book reviews the advances in the field, addressing timely and open questions such as the role of quantum coherence in biology, the role of excess energy in electron injection at photovoltaic interfaces or the dynamics in quantum confined structures (e.g. multi carrier generation). The approach is that of a monograph, with a broad tutorial introduction and an overview of the recent results. This volume includes selected lectures presented at Symposium on Ultrafast Dynamics of the 7th International Conference on Materials for Advanced Technologies.

Download or read book Tunable Multiscale Infrared Plasmonics with Metal Oxide Nanocrystals written by Ankit Agrawal (Ph. D.) and published by . This book was released on 2017 with total page 416 pages. Available in PDF, EPUB and Kindle. Book excerpt: Degenerately doped semiconductor nanocrystals (NC) exhibit a localized surface plasmon resonance (LSPR) that falls in the near- to mid-IR range of the electromagnetic spectrum. Unlike metal, the metal oxide LSPR characteristics can be further tuned by doping, and structural control, or by in situ electrochemical or photochemical charging. Here, we illustrate how intrinsic NC attributes like its crystal structure, shape and size, along with band structure and surface properties affects the LSPR properties and its possible applications. First, the interplay of NC shape and the intrinsic crystal structure on the LSPR was studied using model systems of In:CdO and Cs:WO3, the latter of which has an intrinsic anisotropic crystal structure. For both systems, a change of shape from spherical to faceted NCs led to as anticipated higher near field enhancements around the particle. However, with Cs:WO3, presence of an anisotropic hexagonal crystal structure, leads to additional strong LSPR band-splitting into two distinct peaks with comparable intensities. Second, plasmon-molecular vibration coupling, as a proof of concept for sensing applications, was shown using newly developed F and Sn codoped In2O3 NCs to couple to the C-H vibration of surface-bound oleate ligands. A combined theoretical and experimental approach was employed to describe the observed plasmon-plasmon coupling, the influence of coupling strength and relative detuning between the molecular vibration and LSPR on the enhancement factor, and the observed Fano lineshape by deconvoluting the combined response of the LSPR and molecular vibration in transmission, absorption, and reflection. Third, plasmon modulation through dynamic carrier density tuning was investigated using thin films of monodisperse ITO NCs with various doping level and sizes along with an in situ electrochemical setup. From the combination of the in-situ spectroelectrochemical analysis and optical modeling, it was found that often-neglected semiconductor properties, such as band structure modification upon doping and surface chemistry, strongly affect the LSPR modulation behavior. The influence of band structure and effects like Fermi level pinning by surface defect states were shown to cause a surface depletion layer that alters the LSPR properties, namely the extent of LSPR modulation, near field enhancement, and sensitivity of the LSPR to the surrounding.

Download or read book World Scientific Reference On Plasmonic Nanomaterials Principles Design And Bio applications In 5 Volumes written by and published by World Scientific. This book was released on 2022-03-04 with total page 2475 pages. Available in PDF, EPUB and Kindle. Book excerpt: World Scientific Reference on Plasmonic Nanomaterials: Principles, Design and Bio-applications is a book collection that encompasses multiple aspects of the exciting and timely field of nanoplasmonics, under the coordination of international plasmonic nanomaterials expert, Dr Luis Liz-Marzán. Plasmonics has a long history, from stained glass in ancient cathedrals, through pioneering investigations by Michael Faraday, all the way into the nanotechnology era, where it blossomed into an extremely active field of research with potential applications in a wide variety of technologies.Given the breadth of the materials, phenomena and applications related to plasmonics, this Reference Set offers a collection of chapters within dedicated volumes, focusing on the description of selected phenomena, with an emphasis in chemistry as an enabling tool for the fabrication of, often sophisticated, plasmonic nanoarchitectures and biomedicine as the target application.Basic principles of surface plasmon resonances are described, as well as those mechanisms related to related phenomena such as surface-enhanced spectroscopies or plasmonic chirality. Under the guidance of theoretical models, wet chemistry methods have been implemented toward the synthesis of a wide variety of nanoparticles with different compositions and tailored morphology. But often the optimal nanoarchitecture requires post-synthesis treatments, including functionalization of nanoparticle surfaces, application of external stimuli toward self-assembly into well-defined supraparticle structures and so-called supercrystals. All such nanomaterials can find applications in various biomedical aspects, most often in relation to diagnosis, through either the detection of disease biomarkers at extremely low concentrations or the design of bioimaging methods for in vivo monitoring. Additionally, novel therapeutic tools can also profit from plasmonic nanomaterials, such as photothermal therapy or nanocatalysis.The reference set thus offers comprehensive information of an extremely active subset within the world of plasmonic nanomaterials and their applications, which aims at not just collecting existing knowledge but also promoting further research and technology transfer into the market and the clinic.

Download or read book Recent advances in heavily doped plasmonic copper chalcogenides from synthesis to biological application written by Qiulian Mao and published by OAE Publishing Inc.. This book was released on 2023-05-26 with total page 33 pages. Available in PDF, EPUB and Kindle. Book excerpt: Copper-based chalcogenide compounds have emerged as alternative materials to Cd- or Pb-based traditional semiconductors and have drawn significant attention. Compared with widely reported semiconductors, copper chalcogenide nanocrystals (NCs) with abundant copper defects and vacancies present p-type features. Additionally, the migration of free hole carriers in copper-based chalcogenide NCs produced a metal-like local surface plasmon resonance (LSPR) effect. In this review, we focused on the plasmonic copper chalcogenide NCs achieved through a heavily doped strategy. The copper sulfur compounds with versatile atomic ratios and complex crystal structures exhibit rich electrical, optical, and magnetic properties, making them highly promising for a broad range of applications, from energy conversion to biomedical fields. Therefore, our main focus is on the classification of copper chalcogenide synthesis strategies, theoretical studies of doping, doping strategies, and biological applications. We aim to analyze the trends of copper-based chalcogenide nanomaterials for clinical applications by summarizing previous studies and presenting designs and concepts in a brief manner.

Download or read book Plasmonics and its Applications written by Grégory Barbillon and published by MDPI. This book was released on 2019-06-05 with total page 196 pages. Available in PDF, EPUB and Kindle. Book excerpt: Plasmonics is a rapidly developing field that combines fundamental research and applications ranging from areas such as physics to engineering, chemistry, biology, medicine, food sciences, and the environmental sciences. Plasmonics appeared in the 1950s with the discovery of surface plasmon polaritons. Plasmonics then went through a novel propulsion in the mid-1970s, when surface-enhanced Raman scattering was discovered. Nevertheless, it is in this last decade that a very significant explosion of plasmonics and its applications has occurred. Thus, this book provides a snapshot of the current advances in these various areas of plasmonics and its applications, such as engineering, sensing, surface-enhanced fluorescence, catalysis, and photovoltaic devices.

Download or read book Study of Plasmonic and Magneto optical Properties of Transition Metal Doped Indium Oxide Nanocrystals written by Yi Tan and published by . This book was released on 2019 with total page 78 pages. Available in PDF, EPUB and Kindle. Book excerpt: Plasmonic nanostructure materials have been widely investigated recently because of their considerable potential for applications in biological and chemical sensors, nano-optical devices and photothermal therapy. Compared to metal nanocrystals (NCs), doped semiconductor NCs with tunable localized surface plasmon resonance (LSPR) from near-infrared (NIR) mid-infrared (MIR) region bring more opportunities to the applications of plasmonics. Magnetoplasmonic nanostructures which could be utilized in multifunctional devices also have attracted attention due to the combination of plasmonic and magnetic properties and the manipulation of light with external magnetic fields. In this research, indium oxide (In2O3) as a typical n-type semiconductor with high mobility and carrier concentration is selected as the host lattice for doping, and molybdenum (Mo) and tungsten (W) which are transition metal elements from the same group as dopants. Colloidal molybdenum-doped indium oxide (IMO) NCs and tungsten-doped indium oxide (IWO) NCs with varying doping concentrations have been successfully synthesized, and their plasmonic and magneto-optical properties have been explored. Similarities and differences between IMO NCs and IWO NCs were discussed. Both IMO and IWO NCs have shown good tunability of plasmon resonance in the MIR range approximately from 0.22 eV to 0.34 eV. 9.2 % IMO NCs show the strongest LSPR at 0.34 eV and the maximum free electron concentration of 1.1x1020 cm-3, and 1.5 % IWO NCs exhibit the strongest LSPR at 0.33 eV with the free electron concentration of 0.94x1020 cm-3. The magneto-optical properties were studied by magnetic circular dichroism (MCD) spectroscopy. The variable-temperature-variable-field MCD spectra that coincide with the band gap absorption, indicate the excitonic splitting in the NCs. A robust MCD intensity at room temperature suggests intrinsic plasmon-exciton coupling and carrier polarization induced by plasmon, which might be phonon-mediated. A decrease in MCD signal with temperature and the saturation-like field dependence of MCD intensity for IMO and IWO NCs may related to the different oxidation states of the dopant ions since the reduced 5+ oxidation states can exhibit the Curie-type paramagnetism. IMO and IWO NCs show the coupling between exciton and plasmon in a single-phase which opens a possibility for their application in electronics and photonics. Moreover, magnetoplasmonic modes provide a new degree of freedom for controlling carrier polarization at room temperature in practical photonic, optoelectronic and quantum-information processing devices.

Download or read book Semiconductor Nanomaterials written by Challa S. S. R. Kumar and published by John Wiley & Sons. This book was released on 2010-04-05 with total page 499 pages. Available in PDF, EPUB and Kindle. Book excerpt: The book series Nanomaterials for the Life Sciences, provides an in-depth overview of all nanomaterial types and their uses in the life sciences. Each volume is dedicated to a specific material class and covers fundamentals, synthesis and characterization strategies, structure-property relationships and biomedical applications. The series brings nanomaterials to the Life Scientists and life science to the Materials Scientists so that synergies are seen and developed to the fullest. Written by international experts of various facets of this exciting field of research, the series is aimed at scientists of the following disciplines: biology, chemistry, materials science, physics, bioengineering, and medicine, together with cell biology, biomedical engineering, pharmaceutical chemistry, and toxicology, both in academia and fundamental research as well as in pharmaceutical companies. VOLUME 6 - Semiconductor Nanomaterials

Download or read book Plasmon Induced Carrier Polarization in Semiconductor Nanocrystals written by Penghui Yin and published by . This book was released on 2020 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Currently used technologies are reaching the natural performance limit, invigorating the development of different quantum technologies. Spintronics and valleytronics are emerging quantum electronic technologies that rely on using electron spin and multiple extrema of the band structure (valleys), respectively, as additional degrees of freedom. There are also collective properties of electrons in semiconductor nanostructures that potentially could be exploited in multifunctional quantum devices. Specifically, plasmonic semiconductor nanocrystals (NCs) offer an opportunity for interface-free coupling between a plasmon and an exciton. However, plasmon-exciton coupling in single-phase semiconductor NCs remains challenging because confined plasmon oscillations are generally not resonant with excitonic transitions. In this thesis, using magnetic circular dichroism (MCD) spectroscopy, I examined the electron polarization in plasmonic semiconductor NCs, and the effect of electron localization, plasmon oscillator strength and damping, as well as NC morphology on carrier polarization. The results effectively open up the field of plasmontronics, which involves the phenomena that arise from intrinsic plasmon-exciton and plasmon-spin interactions. Furthermore, the dynamic control of carrier polarization allows us to harness the magnetoplasmonic mode as a new degree of freedom in practical photonic, optoelectronic and quantum-information processing devices. First, we demonstrated the control of excitonic splitting in In2O3 NCs upon excitation with circularly polarized light in an external magnetic field by simultaneous control of the electronic structure of donor defects and the nanocrystal host lattice. Using variable-temperature− variable-field MCD spectroscopy, we show that the NC band splitting has two distinct contributions in plasmonic In2O3 NCs. Temperature-independent splitting arises from the cyclotron magnetoplasmonic modes, which impart angular momentum to the conduction band excited states near the Fermi level, and increases with the intensity of the corresponding plasmon resonance. Temperature-dependent splitting is associated with the localized electron spins trapped in defect states. The ratio of the two components can be controlled by the formation of oxygen vacancies or introduction of aliovalent dopants. Using these experimental results in conjunction with the density functional theory modeling, relative contribution of the two mechanisms is discussed in the context of the perturbation theory taking into account energy separation between the NC excited states and the localized defect states. To implement such opportunities it is essential to develop robust understanding of the parameters that influence magnetoplasmon-induced carrier polarization. I investigated comparatively the plasmonic properties of Mo-doped In2O3 (IMO) and W-doped In2O3 (IWO) NCs, with a particular emphasis on the role of plasmonic properties on excitonic splitting. In contrast to tungsten dopants, which are predominantly in 6+ oxidation state, molybdenum coexists as Mo5+ and Mo6+, resulting in a lower dopant activation in IMO compared to IWO NCs. By manipulating the plasmonic properties of these two NC systems, such as localized surface plasmon resonance energy, intensity, and damping, we identified two opposing influences determining the excitonic Zeeman splitting induced by magnetoplasmonic modes. Localized surface plasmon resonance oscillator strength, commensurate with free carrier density, increases while electron damping, caused by ionized impurity scattering, decreases the transfer of the angular momentum from the magnetoplasmonic modes to the conduction band electronic states. The results contribute to fundamental understanding of the mechanism of non-resonant plasmon-exciton coupling and magnetoplasmon-induced Zeeman splitting in degenerate semiconductor NCs, allowing for the rational design of multifunctional materials with correlated plasmon and charge degrees of freedom. The magnetoplasmon-induced carrier polarization was further attested in oxygen-deficient TiO2 NCs of which the excitonic MCD band has an opposite sign compared to that observed for plasmonic In2O3 NCs indicating the plasmon-induced carrier polarization can be controlled by the electronic properties of NC host lattice. In addition, further manipulation of excitonic splitting in colloidal TiO2 NCs was demonstrated by simple control of their faceting. By changing NC morphology via reaction conditions, I controlled the concentration and location of oxygen vacancies, which can generate localized surface plasmon resonance and foster the reduction of lattice cations leading to the emergence of individual or exchange-coupled Ti(III) centers with high net-spin states. These species can all couple with the nanocrystal lattice under different conditions resulting in distinctly patterned excitonic Zeeman splitting and selective control of conduction band states in an external magnetic field. These results demonstrate that the combination of redox-active vacancy sites and nanocrystal morphology can be used to control quantum states in individual NCs using both localized and collective electronic properties, representing a new approach to complex multifunctionality in reduced dimensions. The results of this work demonstrate the ability to control carrier polarization in nonmagnetic metal oxide NCs using both individual and collective electronic properties, and allow for their application as an emerging class of multifunctional materials with strongly interacting degrees of freedom.

Download or read book Plasmonic Catalysis written by Pedro H.C. Camargo and published by John Wiley & Sons. This book was released on 2021-06-21 with total page 354 pages. Available in PDF, EPUB and Kindle. Book excerpt: Explore this comprehensive discussion of the foundational and advanced topics in plasmonic catalysis from two leaders in the field Plasmonic Catalysis: From Fundamentals to Applications delivers a thorough treatment of plasmonic catalysis, from its theoretical foundations to myriad applications in industry and academia. In addition to the fundamentals, the book covers the theory, properties, synthesis, and various reaction types of plasmonic catalysis. It also covers its applications in reactions including oxidation, reduction, nitrogen fixation, CO2 reduction, and more. The book characterizes plasmonic catalytic systems and describes their properties, tackling the integration of conventional methods as well as new methods able to unravel the optical, electronic, and chemical properties of these systems. It also describes the fundamentals of controlled synthesis of metal nanoparticles relevant to plasmonic catalysis, as well as practical examples thereof. Plasmonic Catalysis covers a wide variety of other practical topics in the field, including hydrogenation reactions and the harvesting of LSPR-excited charge carriers. Readers will also benefit from the inclusion of: A thorough introduction to plasmonic catalysis, a theory of plasmons for catalysis and mechanisms, as well as optical properties of plasmonic-catalytic nanostructures An exploration of the synthesis of plasmonic nanoparticles for photo and electro catalysis, as well as plasmonic catalysis towards oxidation reactions and hydrogenation reactions Discussions of plasmonic catalysis for multi-electron processes and artificial photosynthesis and N2 fixation An examination of control over reaction selectivity in plasmonic catalysis Perfect for catalytic chemists, materials scientists, photochemists, and physical chemists, Plasmonic Catalysis: From Fundamentals to Applications will also earn a place in the libraries of physicists who seek a one-stop resource to enhance their understanding of applications in plasmonic catalysis.

Download or read book Localized Surface Plasmon Resonances in Semiconductor Nanocrystals written by Carl Richard Conti (III) and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation examines the origins of free carrier density in semiconductor nanocrystals and relates these findings to the observed localized surface plasmon resonances (LSPRs). The first chapter introduces some of the most relevant and fundamental concepts in solid state physics, nanomaterials, plasmonics, and key analytical instrumentation used for the studies. Chapter two focuses on what is likely the most famous example of all plasmonic semiconductors, indium tin oxide (ITO) nanocrystals. ITO was one of the first semiconductors shown to exhibit a LSPR, a phenomenon previously thought to only occur in metallic systems such as gold and silver. In this chapter, the concentration of tin dopant is synthetically tuned to investigate its effect on the total number of free carriers generated and their relation to the overserved infrared LSPR. One electron chemical titrations are used to show that the Drude model is shown to be inaccurate for calculating free carrier concentrations and appropriate corrections are proposed. The third chapter examines the effect of dopant size mismatch on free carrier generation. Al3+, Ga3+, and In3+ doped ZnO nanocrystals are synthesized and shown to exhibit unique mid-infrared LSPRs that are not dependent on dopant concentration like is seen in ITO. A combination of infrared spectroscopy, powder X-ray diffraction, and chemical titrations were used to show that better dopant/host ion size matching results in higher free carrier densities. This work is further extended in chapter four, where solid state nuclear magnetic resonance spectroscopy is used as an element specific probe for Al3+ and Ga3+ doped ZnO nanocrystals. Evidence of the formation of an insulating spinel phase (AB2X4) explains the lack of tunability of the LSPR with dopant concentration.

Download or read book Silicon Nanocrystals written by Lorenzo Pavesi and published by John Wiley & Sons. This book was released on 2010-02-02 with total page 648 pages. Available in PDF, EPUB and Kindle. Book excerpt: This unique collection of knowledge represents a comprehensive treatment of the fundamental and practical consequences of size reduction in silicon crystals. This clearly structured reference introduces readers to the optical, electrical and thermal properties of silicon nanocrystals that arise from their greatly reduced dimensions. It covers their synthesis and characterization from both chemical and physical viewpoints, including ion implantation, colloidal synthesis and vapor deposition methods. A major part of the text is devoted to applications in microelectronics as well as photonics and nanobiotechnology, making this of great interest to the high-tech industry.

Download or read book Spectroscopic Analysis of the Thermal and Optical Effects of Plasmon Absorption in Semiconductor Metal Oxide Nanocrystals written by Michelle Ann Blemker and published by . This book was released on 2020 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Plasmonically active materials have the unique ability to use photons to drive a collective multi-electronic oscillatory response. On the nanoscale, this plasmon response gives rise to absorption features previously unseen in bulk materials. This brilliant optical effect has been seen for centuries; suspensions of metallic nanocrystals have been used as a way to achieve beautiful coloration in glassware and art. The nature of this phenomena has only recently been explained in the last century, however, the physics behind the relaxation of electrons driven by this response, and how to exploit them, still desire elucidation. Here, the energetic pathways of electronic absorption and relaxation in plasmonically-active doped semiconductor nanocrystals are studied using spectroscopic and computational methods. We explore the material-dependent properties of the localized surface plasmon resonance in doped metal-oxide nanoparticles, and how to optimize a material for a desired effect. We find that compared to their metallic counterparts, metal oxide nanoparticles have the unique ability to absorb near-infrared light while elevating their electrons to exceedingly high energies. The intense changes in electronic temperatures result in various optical and thermal changes necessary for applications such as electron transfer, biological phototherapies, and optical switching. Next, observable variations to the material’s extinction profile driven by plasmon excitation, whether absorption or reflectivity, are detected using ultrafast spectroscopic methods. The changes are due to alterations in the nanocrystal’s dielectric function due to heating of its electronic and lattice temperatures. We are able to successfully model the ultrafast response of these materials by determining several material constants, that allows us to predict how different materials will behave under plasmon excitation. Lastly, utilization of these plasmonically-active charge carriers for photocatalytic processes is explored. Knowledge of the physics behind how plasmonically-driven electrons respond to photoexcitation allows us to confidently move forward complexing these semiconductors with organic molecules with the goal of directing electron and/or hole transfer with low-energy photons. We find there is much to explore in this area, as the preliminary data suggests plasmonically-enhanced multiphoton absorption by organic semiconductors. The fundamentals of plasmon resonances in semiconductor nanoparticles is vast, yet current research, including this work, suggests their future as a photoactive material is bright

Download or read book Synthesis Characterization and Applications of Plasmonic Semiconductor Nanocrystals written by Su-Wen Hsu and published by . This book was released on 2014 with total page 151 pages. Available in PDF, EPUB and Kindle. Book excerpt: Semiconductor nanostructures are ideal candidates for non-metallic plasmonic materials that operate in the near- to mid-infrared range. In contrast to metal nanostructures, semiconductor nanomaterials have the advantage of possessing tunable carrier concentrations. However, unlike metal nanoparticles which are already widely exploited in plasmonics, little is known about the shape-dependent localized surface plasmon resonances (LSPRs) and near-field electromagnetic behavior of semiconductor nanocrystals. Moreover, a major challenge in the fabrication of plasmonic semiconductor nanomaterials is the ability to control LSPRs by independently varying the size, shape, and carrier density of the nanocrystal. In this dissertation, I describe colloidal synthetic methods for fabricating shaped Cu2-xS nanocrystals in which the morphology and stoichiometry of Cu2-xS can be modulated. These shaped Cu2-xS nanocrystals are used to observe the plasmon response for specific LSPR modes. Specifically, I discuss the plasmon response of Cu2-xS nanodisks as a model nanocrystal system. I demonstrate that LSPR wavelength can be tuned by independently varying the aspect-ratio of the disk and the overall carrier density of the nanocrystal. Increased carrier density in Cu2-xS occurs with oxidation and the formation of copper vacancies, an effect which can be suppressed by carrying out synthesis under an inert atmosphere. Using post-synthetic oxidation, Cu2-xS nanodisks achieve a critical carrier density beyond which the nanocrystals undergo an irreversible phase change, which limits tuning capability. To circumvent this, I use a solvothermal process to generate nanodisks with different crystal phases that enable carrier densities beyond this critical limit. This dissertation also explores the differences in near-field coupling between Cu2-xS nanodisks. These experiments were carried out on self-assembled two-dimensional nanodisk arrays. Varying nanodisk orientation produces a dramatic change in the magnitude and polarization direction of the local field generated by LSPR excitation. Moreover, plasmonic coupling is only observed for Cu2-xS phases that possess carrier densities above a critical value. Overall, this dissertation provides new methods for tuning the plasmonic response of semiconductor nanocrystals by controlling size, shape, and carrier density. It also demonstrates new strategies for designing electromagnetic junctions or coupled plasmonic architectures that operate in the infrared using nanocrystals as building blocks.

Download or read book Magnetic Nanoparticles written by Alberto López-Ortega and published by Royal Society of Chemistry. This book was released on 2024-09-16 with total page 499 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book covers the most cutting-edge developments in the field of magnetic nanoparticles and nanomagnetism, such as novel synthetic and fabrication technologies, diverse magnetic characterization techniques and highly proved and most innovative applications of magnetic nanoparticles. In addition, the book addresses characterization techniques including structural, morphological and magnetic. It is an invaluable reference for experts in the field to consolidate knowledge, provide insight and inspiration to beginners wishing to learn about magnetic nanoparticles. Written at an accessible level suitable for all researchers in materials science, including physicists, biologists, and engineers.