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Full-Text Articles in Nanoscience and Nanotechnology

Thermal Conductivity Of Complex Crystals, High Temperature Materials And Two Dimensional Layered Materials, Xin Qian Jan 2019

Thermal Conductivity Of Complex Crystals, High Temperature Materials And Two Dimensional Layered Materials, Xin Qian

Mechanical Engineering Graduate Theses & Dissertations

Thermal conductivity is a critical property for designing novel functional materials for engineering applications. For applications demanding efficient thermal management like power electronics and batteries, thermal conductivity is a key parameter affecting thermal designs, stability and performances of the devices. Thermal conductivity is also the critical material metrics for applications like thermal barrier coatings (TBCs) in gas turbines and thermoelectrics (TE). Therefore, thermal conductivities of various functional materials have been investigated in the past decade, but most of the materials are simple and isotropic crystals at low temperature. This is because the first-principles calculation is limited to simple crystals at ...


Photoinduced Hole Transfer And Recombination Dynamics Of A Cds Quantum Dot Sensitized Mononuclear Water Oxidation Catalyst, Orion Magruder Pearce Jan 2019

Photoinduced Hole Transfer And Recombination Dynamics Of A Cds Quantum Dot Sensitized Mononuclear Water Oxidation Catalyst, Orion Magruder Pearce

Chemistry & Biochemistry Graduate Theses & Dissertations (1986-2018)

Artificial photosynthesis represents a promising strategy to capture and store solar energy through the production of carbon neutral fuels. This process begins with absorption of a photon by a semiconductor creating an electron-hole pair which are then separated and used to drive reduction and oxidation reactions. CdS nanostructures are model light absorbers for studying these charge transfer reactions and have already demonstrated photoinduced electron transfer to drive a variety of reactions. However, there has been comparatively little progress in understanding how CdS nanostructures may be used to sensitize oxidation reactions such as water oxidation. To this end, we undertook a ...


Plasmonic And Upconversion Nanoparticles For Bladder Cancer Treatment, Suehyun Katherine Cho Apr 2018

Plasmonic And Upconversion Nanoparticles For Bladder Cancer Treatment, Suehyun Katherine Cho

Electrical, Computer & Energy Engineering Graduate Theses & Dissertations

This thesis reports syntheses and surface modifications of various nanoparticles, including plasmonic, upconversion, and indium tin oxide nanoparticles for in situ bladder cancer detection and treatment.

The first part of this thesis reports a new and efficient polyethylene glycol (PEG) coating of gold nanorods (AuNRs). This coating technique is proven not only to be more stable in water compared to conventional coating methods, but also allows conjugation of an anti-epidermal growth factor receptor, C-225 antibodies. The AuNRs conjugated with C-225 antibodies (CNR) is then used in both in vitro and in vivo settings to demonstrate specific, targeted treatment capabilities by ...


Liquid Crystals Formed By Short Dna Oligomers And The Origin Of Life, Gregory Patrick Smith Jan 2018

Liquid Crystals Formed By Short Dna Oligomers And The Origin Of Life, Gregory Patrick Smith

Physics Graduate Theses & Dissertations

When dissolved in water, base paired DNA oligomers form double helices with sufficient structural rigidity that, if they are at high enough concentration, can undergo a phase transition into chiral nematic or hexagonal columnar liquid crystalline (LC) order. Within these LC phases, constrained orientation allows these rods to stack more efficiently by hydrophobic forces than they would otherwise, building them into long double helical aggregates that can be chemically glued together (ligated) to further increase their lengths. Even in absence of chemical ligation, this stacking effect is strong enough that short DNA oligomers, which are otherwise too short to form ...


Designing Materials For Inorganic And Living Photocatalytic Systems For Air, Water, And Co2 Reduction From Sunlight, Yuchen Ding Jan 2018

Designing Materials For Inorganic And Living Photocatalytic Systems For Air, Water, And Co2 Reduction From Sunlight, Yuchen Ding

Chemistry & Biochemistry Graduate Theses & Dissertations (1986-2018)

Several strategies are currently being investigated for conversion of incident sunlight into chemical fuels, with readily available chemical feedstocks like air, water, and carbon-dioxide. This thesis focuses on research approach on designing high-efficiency and high-selective photocatalytic materials, ranging from inexpensive and stable inorganic photocatalysts to living nano-biohybrid organisms to achieve solar energy conversion.

This thesis is divided into multiple sections based on the materials and concepts in designing high-efficient and high-selective solar fuel generator. After a brief introduction of photocatalysis in Chapter 1, we describe a novel electrochemical anodization technique for making a wide-variety of doped metal-oxide nanotubes. Using optoelectronic ...


Excited-State Dynamics Of Semiconductor Nanocrystals: Trapped-Hole Diffusion And Electron-Transfer Kinetics In Cds And Cdse Nanorods, James Keller Utterback Jan 2018

Excited-State Dynamics Of Semiconductor Nanocrystals: Trapped-Hole Diffusion And Electron-Transfer Kinetics In Cds And Cdse Nanorods, James Keller Utterback

Chemistry & Biochemistry Graduate Theses & Dissertations (1986-2018)

Colloidal semiconductor nanocrystals have many remarkable properties—such as exceptionally tunable excited states and surface chemistry—that have led to an enthusiastic interest in using them for optoelectronic applications such as solar-energy conversion. Such technologies require control over the generation, separation, and extraction of photoexcited electrons and holes. However, the interpretation of experimentally measured excited-state decay curves is challenging because they typically exhibit complicated shapes that are elusive to simple kinetic models. To understand the principles that govern electron and hole relaxation dynamics in these complex systems, models rooted in fundamental physical phenomena are needed. This dissertation describes efforts to ...


Using Semiconductor Nanocrystals To Drive Redox Enzymes With Light, Hayden Tyler Hamby Jan 2018

Using Semiconductor Nanocrystals To Drive Redox Enzymes With Light, Hayden Tyler Hamby

Chemistry & Biochemistry Graduate Theses & Dissertations (1986-2018)

Nanocrystals are an emergent strategy for providing electrons to redox enzymes for catalysis. In this dissertation I present my work on the investigation of how nanocrystals can be used to drive active site chemistry of two different enzymes. In the first project I present for the first time the direct coupling of cadmium sulfide nanorods (CdS NRs) to a CO2 reduction enzyme for the creation of new carbon-carbon bonds using light. Under optimal conditions, the maximum turnover frequency (TOFmax) for CO2 reduction is similar to that obtained in the native system where the native electron donor ferredoxin ...


Revealing The Nanoscale Structure And Properties Of The Twist-Bend Nematic Liquid Crystal Phase, Michael Ryan Tuchband Jan 2018

Revealing The Nanoscale Structure And Properties Of The Twist-Bend Nematic Liquid Crystal Phase, Michael Ryan Tuchband

Physics Graduate Theses & Dissertations

The nematic phases of liquid crystals have been the most thoroughly investigated since the founding of the liquid crystal field in the early 1900’s. The resulting technologies, most notably the liquid crystal display, have changed our world and spawned an entire industry. Consequently, the recent identification of a new type of nematic – the twist-bend nematic – was met with as much surprise as excitement, as it melds the fluid properties and environmental responsiveness of conventional nematics with the intrinsic polarization and complex ordering of bent-core liquid crystals. I summarize the history of the twist-bend nematic phase, charting the development of ...


Exceeding Conventional Photovoltaic Efficiency Limits Using Colloidal Quantum Dots, Gregory F. Pach Apr 2017

Exceeding Conventional Photovoltaic Efficiency Limits Using Colloidal Quantum Dots, Gregory F. Pach

Electrical, Computer & Energy Engineering Graduate Theses & Dissertations

Colloidal quantum dots (QDs) are a widely investigated field of research due to their highly tunable nature in which the optical and electronic properties of the nanocrystal can be manipulated by merely changing the nanocrystal’s size. Specifically, colloidal quantum dot solar cells (QDSCs) have become a promising candidate for future generation photovoltaic technology. Quantum dots exhibit multiple exciton generation (MEG) in which multiple electron-hole pairs are generated from a single high-energy photon. This process is not observed in bulk-like semiconductors and allows for QDSCs to achieve theoretical efficiency limits above the standard single-junction Shockley-Queisser limit. However, the fast expanding ...


Exceeding Conventional Photovoltaic Efficiency Limits Using Colloidal Quantum Dots, Gregory F. Pach Jan 2017

Exceeding Conventional Photovoltaic Efficiency Limits Using Colloidal Quantum Dots, Gregory F. Pach

Electrical Engineering Graduate Theses & Dissertations

Colloidal quantum dots (QDs) are a widely investigated field of research due to their highly tunable nature in which the optical and electronic properties of the nanocrystal can be manipulated by merely changing the nanocrystal’s size. Specifically, colloidal quantum dot solar cells (QDSCs) have become a promising candidate for future generation photovoltaic technology. Quantum dots exhibit multiple exciton generation (MEG) in which multiple electron-hole pairs are generated from a single high-energy photon. This process is not observed in bulk-like semiconductors and allows for QDSCs to achieve theoretical efficiency limits above the standard single-junction Shockley-Queisser limit. However, the fast expanding ...


Quantum Measurement Backaction And Upconverting Microwave Signals With Mechanical Resonators, Robert William Peterson Jan 2017

Quantum Measurement Backaction And Upconverting Microwave Signals With Mechanical Resonators, Robert William Peterson

Physics Graduate Theses & Dissertations

The limits of optical measurement and control of mechanical motion are set by the quantum nature of light. The familiar shot noise limit can be avoided by increasing the optical power, but at high enough powers, the backaction of the randomly-arriving photons' radiation pressure can grow to become the dominant force on the system. This thesis will describe an experiment showing how backaction limits the laser cooling of macroscopic drumhead membranes, as well as work on how these membranes can be used to upconvert microwave signals to optical frequencies, potentially preserving the fragile quantum state of the upconverted signal.


Nanoscale And Ultrafast Imaging And Spectroscopy To Probe Heterogeneity Of Novel Materials And Coherence Of Thermal Near-Fields, Brian Thomas O'Callahan Jan 2017

Nanoscale And Ultrafast Imaging And Spectroscopy To Probe Heterogeneity Of Novel Materials And Coherence Of Thermal Near-Fields, Brian Thomas O'Callahan

Physics Graduate Theses & Dissertations

Novel optical phenomena emerge on nanometer length scales which determine the macroscopic material response. By bringing a sharp atomic force microscopy tip close to a surface and illuminating with either a laser, a broadband light source, or the intrinsic thermal fields of the material itself, we can probe near-field optical properties with spatial resolution only limited by the apex radius of the tip. These properties include the spectral, spatial, and coherence properties of the thermal near-fields that emerge at sub-wavelength distances from any matter at non-zero temperature that affect thermal emission and nanoscale heat transfer. I also apply near-field imaging ...


Uncovering New Thermal And Elastic Properties Of Nanostructured Materials Using Coherent Euv Light, Jorge Nicolás Hernández Charpak Jan 2017

Uncovering New Thermal And Elastic Properties Of Nanostructured Materials Using Coherent Euv Light, Jorge Nicolás Hernández Charpak

Physics Graduate Theses & Dissertations

Advances in nanofabrication have pushed the characteristic dimensions of nanosystems well below 100nm, where physical properties are often significantly different from their bulk counterparts, and accurate models are lacking. Critical technologies such as thermoelectrics for energy harvesting, nanoparticle-mediated thermal therapy, nano-enhanced photovoltaics, and efficient thermal management in integrated circuits depend on our increased understanding of the nanoscale. However, traditional microscopic characterization tools face fundamental limits at the nanoscale. Theoretical efforts to build a fundamental picture of nanoscale thermal dynamics lack experimental validation and still struggle to account for newly reported behaviors. Moreover, precise characterization of the elastic behavior of nanostructured ...


Coherent Femtosecond Spectroscopy And Nonlinear Optical Imaging On The Nanoscale, Vasily Kravtsov Jan 2017

Coherent Femtosecond Spectroscopy And Nonlinear Optical Imaging On The Nanoscale, Vasily Kravtsov

Physics Graduate Theses & Dissertations

Optical properties of many materials and macroscopic systems are defined by ultrafast dynamics of electronic, vibrational, and spin excitations localized on the nanoscale. Harnessing these excitations for material engineering, optical computing, and control of chemical reactions has been a long-standing goal in science and technology. However, it is challenging due to the lack of spectroscopic techniques that can resolve processes simultaneously on the nanometer spatial and femtosecond temporal scales. This thesis describes the fundamental principles, implementation, and experimental demonstration of a novel type of ultrafast microscopy based on the concept of adiabatic plasmonic nanofocusing. Simultaneous spatio-temporal resolution on a nanometer-femtosecond ...


Controlling The Photophysical Properties Of Semiconductor Quantum Dot Arrays By Strategic Alteration Of Their Surface Chemistry, Ashley R. Marshall Jan 2017

Controlling The Photophysical Properties Of Semiconductor Quantum Dot Arrays By Strategic Alteration Of Their Surface Chemistry, Ashley R. Marshall

Chemistry & Biochemistry Graduate Theses & Dissertations (1986-2018)

Semiconductor quantum dots (QDs) are interesting materials that, after less than 40 years of research, are used in commercial products. QDs are now found in displays, such as Samsung televisions and the Kindle Fire, and have applications in lighting, bio-imaging, quantum computing, and photovoltaics. They offer a large range of desirable properties: a controllable band gap, solution processability, controlled energy levels, and are currently the best materials for multiple exciton generation. The tunable optoelectronic properties of QDs can be controlled using size, shape, composition, and surface treatments—as shown here. Due to the quasi-spherical shape of QDs the surface to ...


Photophysics And Electron Transfer Dynamics Of Type-Ii And Quasi Type-Ii Heterostructure Nanocrystals, Amanda Norell Grennell Jan 2017

Photophysics And Electron Transfer Dynamics Of Type-Ii And Quasi Type-Ii Heterostructure Nanocrystals, Amanda Norell Grennell

Chemistry & Biochemistry Graduate Theses & Dissertations (1986-2018)

Type-II and quasi type-II heterostructure nanocrystals are known to exhibit extended excited-state lifetimes compared to their single material counterparts because of reduced wavefunction overlap between the electron and hole. Thus, type-II heterostructures are promising materials for solar-to-fuel conversion, as extended excited-state lifetimes make transfer of charges to a catalyst more competitive with intrinsic nanocrystal decay processes. However, due to fast and efficient hole trapping and non-uniform morphologies, the photophysics of dot-in-rod heterostructures are more rich and complex than this simple picture. Using transient absorption spectroscopy, we observe that the behavior of electrons in the CdS “rod” or “bulb” regions of ...


Photophysics And Electron Transfer Dynamics Of Type-Ii And Quasi Type-Ii Heterostructure Nanocrystals, Amanda N. Grennell Jan 2017

Photophysics And Electron Transfer Dynamics Of Type-Ii And Quasi Type-Ii Heterostructure Nanocrystals, Amanda N. Grennell

Chemistry & Biochemistry Graduate Theses & Dissertations (1986-2018)

Type-II and quasi type-II heterostructure nanocrystals are known to exhibit extended excited-state lifetimes compared to their single material counterparts because of reduced wavefunction overlap between the electron and hole. Thus, type-II heterostructures are promising materials for solar-to-fuel conversion, as extended excited-state lifetimes make transfer of charges to a catalyst more competitive with intrinsic nanocrystal decay processes. However, due to fast and efficient hole trapping and non-uniform morphologies, the photophysics of dot-in-rod heterostructures are more rich and complex than this simple picture. Using transient absorption spectroscopy, we observe that the behavior of electrons in the CdS “rod” or “bulb” regions of ...


Effect Of Hydration And Confinement On Micro-Structure Of Calcium-Silicate-Hydrate Gels, Harish Kumar Gadde Jan 2017

Effect Of Hydration And Confinement On Micro-Structure Of Calcium-Silicate-Hydrate Gels, Harish Kumar Gadde

Civil Engineering Graduate Theses & Dissertations

Calcium-silicate-hydrate(C-S-H) gel is a primary nano-crystalline phase present in hydrated Ordinary Portland Cement (OPC) responsible for its strength and creep behavior. Our reliance on cement for infrastructure is global, and there is a need to improve infrastructure life-times. A way forward is to engineer the cement with more durability and long-term strength. The main purpose of this research is to quantify the micro-structure of C-S-H to see if cement can be engineered at various length scales to improve long-term behavior by spatial arrangement. We investigate the micro-structure evolution of C-S-H in cement as a function of hydration time and ...


Effect Of Hydration And Confinement On Micro-Structure Of Calcium-Silicate-Hydrate Gels, Harish Kumar Gadde Jan 2017

Effect Of Hydration And Confinement On Micro-Structure Of Calcium-Silicate-Hydrate Gels, Harish Kumar Gadde

Civil Engineering Graduate Theses & Dissertations

Calcium-silicate-hydrate(C-S-H) gel is a primary nano-crystalline phase present in hydrated Ordinary Portland Cement (OPC) responsible for its strength and creep behavior. Our reliance on cement for infrastructure is global, and there is a need to improve infrastructure life-times. A way forward is to engineer the cement with more durability and long-term strength. The main purpose of this research is to quantify the micro-structure of C-S-H to see if cement can be engineered at various length scales to improve long-term behavior by spatial arrangement. We investigate the micro-structure evolution of C-S-H in cement as a function of hydration time and ...


Quantum Dot Nanobioelectronics And Selective Antimicrobial Redox Interventions, Samuel Martin Goodman Jan 2016

Quantum Dot Nanobioelectronics And Selective Antimicrobial Redox Interventions, Samuel Martin Goodman

Chemical & Biological Engineering Graduate Theses & Dissertations

The unique properties of nanomaterials have engendered a great deal of interest in applying them for applications ranging from solid state physics to bio-imaging. One class of nanomaterials, known collectively as quantum dots, are defined as semiconducting crystals which have a characteristic dimension smaller than the excitonic radius of the bulk material which leads to quantum confinement effects. In this size regime, excited charge carriers behave like prototypical particles in a box, with their energy levels defined by the dimensions of the constituent particle. This is the source of the tunable optical properties which have drawn a great deal of ...


Scattering-Scanning Near-Field Optical Microscopy With Femtosecond Laser Pulses, Peter B. Van Blerkom Jan 2016

Scattering-Scanning Near-Field Optical Microscopy With Femtosecond Laser Pulses, Peter B. Van Blerkom

Physics Graduate Theses & Dissertations

The macroscopic properties of materials we observe emerge from the collective structural configuration and dynamical behavior of the atomic or molecular constituents. Therefore, in order to fully characterize and understand these properties, it is necessary to develop measurement techniques capable of probing at these scales. Such a technique is that of combining scattering scanning near-field optical microscopy with ultrafast spectroscopy. Traditional, far-field microscopy is limited by diffraction, making it impossible to resolve details smaller than approximately half the wavelength of the illuminating light. However, the electromagnetic field that is produced when an object is illuminated is not simply characterized by ...


Shape Memorization And Reconfiguration Of Polymer Particles, Lewis Michael Cox Jan 2016

Shape Memorization And Reconfiguration Of Polymer Particles, Lewis Michael Cox

Mechanical Engineering Graduate Theses & Dissertations

Polymer particle systems have been experienced tremendous research efforts in recent years owing to their rapidly expanding applications. Improvements in synthesis methodologies have resulted in unprecedented control over the structure and chemistry of particles. In contrast to these advancements, knowledge of the experimental studies of the mechanical properties of particles remains scarce. Smart particles, specimens capable of changing shape in response to external stimuli, have specifically begun to attract attention. In this thesis two different smart particle systems capable of conforming to an infinite spectrum of user-controlled geometries are investigated: shape memory and shape reconfiguring particles.

Shape memory polymers have ...


Graphene-Semiconductor Heterojunctions And Devices, Tzu-Min Ou Apr 2015

Graphene-Semiconductor Heterojunctions And Devices, Tzu-Min Ou

Electrical, Computer & Energy Engineering Graduate Theses & Dissertations

In this thesis we explore the potential of versatile graphene-semiconductor heterojunctions in photodetection and field-effect transistor (FET) applications. The first part of the thesis studies near-infrared photodiode (NIR PD) based on a graphene- n-Si heterojunction in which graphene is used as the absorbing medium. Graphene is chosen for its absorption in NIR wavelengths to which Si is not responsive. Most graphene detectors in the literature are photoconductors that have a high dark current. The graphene-Si heterojunction PD has a large Schottky barrier height that suppresses the dark current and enhances the current rectification and the photon detectivity.

The fabricated graphene-Si ...


Simulation Studies Of Diblock-Copolymer Grafted Nanoparticle Assembly In Solvent And Polymer Matrix, Carla E. Estridge Jan 2015

Simulation Studies Of Diblock-Copolymer Grafted Nanoparticle Assembly In Solvent And Polymer Matrix, Carla E. Estridge

Chemistry & Biochemistry Graduate Theses & Dissertations (1986-2018)

Macroscopic properties of polymer nanocomposites are fundamentally linked to the morphology (or assembled structure) of its constituents. In order to design composites to have specific macroscopic properties it is important to be able to control the assembly of the constituents in the composite. In this thesis we use molecular simulations to study the molecular-level interactions and assembly of one class of polymer nanocomposites, namely diblock-copolymer grafted nanoparticles in solvent and in polymer matrix.

First, we study how the molecular features of the diblock-copolymer grafts affect the assembly of grafted nanoparticles in a (implicit) small molecule solvent. Using coarse-grained molecular dynamics ...


Charge Transfer Dynamics In Complexes Of Light-Absorbing Cds Nanorods And Redox Catalysts, Molly Bea Wilker Jan 2015

Charge Transfer Dynamics In Complexes Of Light-Absorbing Cds Nanorods And Redox Catalysts, Molly Bea Wilker

Chemistry & Biochemistry Graduate Theses & Dissertations (1986-2018)

The use of photoexcited electrons and holes in semiconductor nanocrystals as reduction and oxidation reagents is an intriguing way of harvesting photon energy to drive chemical reactions. This dissertation describes research efforts to understand the photoexcited charge transfer kinetics in complexes of colloidal CdS nanorods coupled with either a water oxidation or reduction catalyst. The first project focuses on the charge transfer interactions between photoexcited CdS nanorods and a mononuclear water oxidation catalyst derived from the [Ru(bpy)(tpy)Cl]+ parent structure. Upon excitation, hole transfer from CdS oxidizes the catalyst (Ru2+→Ru3+) on a 100 ps – 1 ...


Interactions Of Nanomaterials With Biological Systems: A Study Of Bio-Mineralized Nanoparticles And Nanoparticle Antibiotics, Jennifer Chappell Gifford Jan 2015

Interactions Of Nanomaterials With Biological Systems: A Study Of Bio-Mineralized Nanoparticles And Nanoparticle Antibiotics, Jennifer Chappell Gifford

Chemistry & Biochemistry Graduate Theses & Dissertations (1986-2018)

Nature is continually able to out-perform laboratory syntheses of nanomaterials with control of specific properties under ambient temperatures, pressures and pH. The investigation of existing biomolecule-mediated nanoparticle synthesis provides insight and knowledge necessary for duplicating these processes. In this way, peptides or proteins with nanomaterial mediation capabilities can be: 1) explored to further understand the ways in which biomolecules create specific nanoparticles then 2) used to create genetically encodable tags for use in electron tomography. The goal of designing such a tag was to assist in closing the resolution gap that exists in current imaging techniques between approximately 5 nm ...


Uncovering New Thermal And Mechanical Behavior At The Nanoscale Using Coherent Extreme Ultraviolet Light, Kathleen Marie Hoogeboom-Pot Jan 2015

Uncovering New Thermal And Mechanical Behavior At The Nanoscale Using Coherent Extreme Ultraviolet Light, Kathleen Marie Hoogeboom-Pot

Physics Graduate Theses & Dissertations

Tremendous recent progress in nanofabrication capabilities has made high-quality single-atomic layers and nanostructures with dimensions well below 50 nm commonplace, enabling unprecedented access to materials at the nanoscale. However, tools and techniques capable of characterizing the properties and function of nanosystems are still quite limited, leaving much of the fundamental physics that dominates material behavior in the deep nano-regime still unknown. Further understanding gained by studying nanoscale materials is critical both to fundamental science and to continued technological development. This thesis applies coherent extreme ultraviolet (EUV) light from tabletop high harmonic generation to study nanoscale systems on their intrinsic length ...


Novel Concepts In Near-Field Optics: From Magnetic Near-Field To Optical Forces, Honghua Yang Jan 2015

Novel Concepts In Near-Field Optics: From Magnetic Near-Field To Optical Forces, Honghua Yang

Physics Graduate Theses & Dissertations

Driven by the progress in nanotechnology, imaging and spectroscopy tools with nanometer spatial resolution are needed for in situ material characterizations. Near-field optics provides a unique way to selectively excite and detect elementary electronic and vibrational interactions at the nanometer scale, through interactions of light with matter in the near-field region. This dissertation discusses the development and applications of near-field optical imaging techniques, including plasmonic material characterization, optical spectral nano-imaging and magnetic field detection using scattering-type scanning near-field optical microscopy (s-SNOM), and exploring new modalities of optical spectroscopy based on optical gradient force detection.

Firstly, the optical dielectric functions ...


Ultra-Thin Materials From Atomic Layer Deposition For Microbolometers, Nathan Thomas Eigenfeld Jan 2015

Ultra-Thin Materials From Atomic Layer Deposition For Microbolometers, Nathan Thomas Eigenfeld

Mechanical Engineering Graduate Theses & Dissertations

This research focuses on the incorporation of atomic layer deposition (ALD) materials into microbolometer devices for infrared (IR) imaging. Microbolometers are suspended micro-electromechanical (MEMS) devices, which respond electrically to absorbed IR radiation. By minimizing the heat capacity (thermal mass) of these devices, their performance may be substantially improved. Thus, implementing ultra-thin freestanding ALD materials into microbolometer devices will offer a substantial reduction in the overall heat capacity of the device. A novel nanofabrication method is developed to produce robust ultra-thin suspended structures from ALD generated materials including W, Ru and Al2O3. Unique aspects of ALD such as high conformality offer ...


Graphene Geometric Diodes For Optical Rectennas, Zixu James Zhu Jul 2014

Graphene Geometric Diodes For Optical Rectennas, Zixu James Zhu

Electrical, Computer & Energy Engineering Graduate Theses & Dissertations

Optical rectennas, which are micro-antennas to convert optical-frequency radiation to alternating current combined with ultrahigh-speed diodes to rectify the current, can in principle provide high conversion efficiency solar cells and sensitive detectors. Currently investigated optical rectennas using metal/insulator/metal (MIM) diodes are limited in their RC response time and poor impedance matching between diodes and antennas. A new rectifier, the geometric diode, can overcome these limitations. The thesis work has been to develop geometric diode rectennas, along with improving fabrication processes for MIM diode rectennas. The geometric diode consists of a conducting thin-film, currently graphene, patterned into a geometry ...