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Full-Text Articles in Physics

Light Matter Interaction In Single Molecule Magnets, Rebecca Cebulka May 2019

Light Matter Interaction In Single Molecule Magnets, Rebecca Cebulka

Electronic Theses and Dissertations

This dissertation includes a series of experimental realizations which focus on studying the coupling between photons and single-molecule magnets (SMMs) in both the weak and strong coupling regimes. In the weak coupling regime, the aim is to achieve coherent control over the time evolution of the spin of SMMs while applying rapid microwave pulses at sub-Kelvin temperatures, where polarization of the spin bath may be achieved without large magnetic fields, allowing the suppression of dipolar dephasing. The continuing results of this experiment will be to provide a window into fundamental sources of decoherence in single-crystal SMMs in an energy range ...


A Theoretical Investigation Of Small Organic Molecules On Transition Metal Surfaces, Walter Malone May 2019

A Theoretical Investigation Of Small Organic Molecules On Transition Metal Surfaces, Walter Malone

Electronic Theses and Dissertations

With the ever growing number of proposed desnity functional theory (DFT) functionals it becomes necessary to thoroughly screen any new method to determine its merit. Especially relevant methods include a proper description of the van der Waals (vdW) interaction, which can prove vital to a correct description of a myriad of systems of technological importance. The first part of this dissertation explores the utility of several vdW-inclusive DFT functionals including optB86b-vdW, optB88-vdW, optPBE-vdW, revPBE-vdW, rPW86-vdW2, and SCAN+rVV10 by applying them to model systems of small organic molecules, pyridine and thiophene, on transition metal surfaces. Overall, we find the optB88-vdW ...


Chemistry And Dissipation At Mineral Surfaces In The Space Environment, William Tucker May 2019

Chemistry And Dissipation At Mineral Surfaces In The Space Environment, William Tucker

Electronic Theses and Dissertations

The composition and morphology of mineral surfaces is known to play an important role in various phenomena relevant to planetary science. For example, the synthesis and processing of complex organics likely occurs at mineral surfaces strongly affected by the space environment. Furthermore, the dissipative and adhesive properties of dust grains may depend strongly on the chemical state of the surface including the presence of dangling bonds, adsorbates, and radicals. In this dissertation, experimental results are first presented which demonstrate that mineral grains subjected to high temperatures in a reducing environment lead to iron nanoparticles which are strongly catalytic for the ...


Fundamental Properties Of Metallic Nanolasers, William Hayenga Jan 2019

Fundamental Properties Of Metallic Nanolasers, William Hayenga

Electronic Theses and Dissertations

The last two decades have witnessed tremendous advancements in the area of nanophotonics and plasmonics, which has helped propel the development of integrated photonic sources. Of central importance to such circuits is compact, scalable, low threshold, and efficient coherent sources that can be driven at high modulation frequencies. In this regard, metallic nanolasers offer a unique platform. Their introduction has enabled confinement of light at a subwavelength scale and the ultra-small size of the modes afforded by these structures allows for cavity enhancing effects that can help facilitate thresholdless lasing and large direct modulation bandwidths. In this report, I present ...


Broadband Mid-Infrared Frequency Combs Generated Via Frequency Division, Qitian Ru Jan 2019

Broadband Mid-Infrared Frequency Combs Generated Via Frequency Division, Qitian Ru

Electronic Theses and Dissertations

Frequency combs have revolutionized metrology and demonstrated numerous applications in science and technology. Combs operating in the mid-infrared region could be beneficial for molecular spectroscopy for several reasons. First, numerous molecules have their spectroscopic signatures in this region. Furthermore, the atmospheric window (3-5μm and 8-14μm) is located here. Additionally, a mid-infrared frequency comb could be employed as a diagnostic tool for the many components of human breath, as well as for detection of harmful gases and contaminants in the atmosphere. In this thesis, I used synchronously pumped subharmonic optical parametric oscillators (OPOs) operating at degeneracy to produce ultra-broadband outputs near ...


Holographic Optical Elements For Visible Light Applications In Photo-Thermo-Refractive Glass, Fedor Kompan Jan 2019

Holographic Optical Elements For Visible Light Applications In Photo-Thermo-Refractive Glass, Fedor Kompan

Electronic Theses and Dissertations

This dissertation reports on design and fabrication of various optical elements in Photo-thermo-refractive (PTR) glass. An ability to produce complex holographic optical elements (HOEs) for the visible spectral region appears very beneficial for variety of applications, however, it is limited due to photosensitivity of the glass confined within the UV region. First two parts of this dissertation present two independent approaches to the problem of holographic recording using visible radiation. The first method involves modification of the original PTR glass rendering it photosensitive to radiation in the visible spectral region and, thus, making possible the recording of holograms in PTR ...


Structure Difference And Implication To Assembly Morphology Control Of Rous Sarcoma Virus Capsid Protein, John Hastings Jan 2019

Structure Difference And Implication To Assembly Morphology Control Of Rous Sarcoma Virus Capsid Protein, John Hastings

Honors Undergraduate Theses

Rous Sarcoma Virus (RSV) is an avian retrovirus with an enclosing capsid protein (CA) shell. RSV CA is studied due to its similar molecular structure to other retrovirus capsid proteins such as Human Immunodeficiency Virus (HIV). In this project, turbidity assay is used to track the assembly process of RSV CA, while solid state nuclear magnetic resonance (ssNMR) is used to probe the CA structure at a site specific level and investigate the morphology of the spherical structure of the I190V mutated strain of RSV CA. The I190V mutant is a naturally occurring mutation and is able to form into ...


Third-Order Optical Nonlinearities For Integrated Microwave Photonics Applications, Marcin Malinowski Jan 2019

Third-Order Optical Nonlinearities For Integrated Microwave Photonics Applications, Marcin Malinowski

Electronic Theses and Dissertations

The field of integrated photonics aims at compressing large and environmentally-sensitive optical systems to micron-sized circuits that can be mass-produced through existing semiconductor fabrication facilities. The integration of optical components on single chips is pivotal to the realization of miniature systems with high degree of complexity. Such novel photonic chips find abundant applications in optical communication, spectroscopy and signal processing. This work concentrates on harnessing nonlinear phenomena to this avail. The first part of this dissertation discusses, both from component and system level, the development of a frequency comb source with a semiconductor mode-locked laser at its heart. New nonlinear ...


High Performance Liquid Crystal Devices For Augmented Reality And Virtual Reality, Md Javed Rouf Talukder Jan 2019

High Performance Liquid Crystal Devices For Augmented Reality And Virtual Reality, Md Javed Rouf Talukder

Electronic Theses and Dissertations

See-through augmented reality and virtual reality displays are emerging due to their widespread applications in education, engineering design, medical, retail, transportation, automotive, aerospace, gaming, and entertainment. For augmented reality and virtual reality displays, high-resolution density, high luminance, fast response time and high ambient contrast ratio are critically needed. High-resolution density helps eliminate the screen-door effect, high luminance and fast response time enable low duty ratio operation, which plays a key role for suppressing image blurs. A dimmer placed in front of AR display helps to control the incident background light, which in turn improves the image contrast. In this dissertation ...


Asteroid Surfaces: The Importance Of Cohesive Forces, Keanna Jardine Jan 2019

Asteroid Surfaces: The Importance Of Cohesive Forces, Keanna Jardine

Electronic Theses and Dissertations

Adhesive forces play a significant role on airless bodies due to their weak gravities. Investigating adhesion at the surface of asteroids and their constituent components is vital to understanding their formation and evolution. Previous research has been done to understand the interaction of micron-sized spheres to planar surfaces and sphere-to-sphere interactions, which have been used to develop models of asteroid surfaces. Our investigation experimentally investigates adhesion through atomic force microscopy (AFM) measurements between JSC-1 simulant particles and several AFM tips, including a typical pyramidal gold tip and microspheres of sizes 2 μm and 15 μm. The samples of JSC-1 consist ...


Grating Coupler For Surface Waves Based On Electrical Displacement Currents, Jonathan R. Brescia Jan 2019

Grating Coupler For Surface Waves Based On Electrical Displacement Currents, Jonathan R. Brescia

Honors Undergraduate Theses

Bound electromagnetic surface waves can be excited by free-space waves on a corrugated conduction surface. These electromagnetic surface waves, called surface plasmon polaritons (SPPs), are coupled to a plasma of free charges, which travel together with the wave. We investigated the effect of separating metal corrugations from the smooth metal ground plane with a thin dielectric layer and show that SPPs can be excited via displacement currents. However, the SPP excitation resonances broaden and disappear as the dielectric thickness approaches 1% of the wavelength.


Far-Infrared Bands In Plasmonic Metal-Insulator-Metal Absorbers Optimized For Long Wave Infrared, Rachel Evans Jan 2018

Far-Infrared Bands In Plasmonic Metal-Insulator-Metal Absorbers Optimized For Long Wave Infrared, Rachel Evans

Electronic Theses and Dissertations

Metal–insulator–metal (MIM) resonant absorbers comprise a conducting ground plane, a thin dielectric, and thin separated metal top-surface structures. Long-wave infrared (LWIR) fundamental absorptions are experimentally shown to be optimized for a ratio of dielectric thickness to top-structure dimension t/l > 0.08. The fundamental resonance wavelength is predicted by different analytic standing-wave theories to be ~2nl, where n is the dielectric refractive index. Thus, for the dielectrics SiO2, AlN, and TiO2, l values of a few microns give fundamentals in the 8-12 micron LWIR wavelength region. Agreement of observed fundamental resonance wavelength with theory is better for t ...


Development Of A Tabletop Coherent Soft X-Ray Source, Hanfu Kong Jan 2018

Development Of A Tabletop Coherent Soft X-Ray Source, Hanfu Kong

Electronic Theses and Dissertations

The goal of this thesis is to design a tabletop coherent soft X-ray source for attosecond high resolution imaging. We collect signals from gas cells with different length and lens with different focal length. A spectrometer with a grating and a CCD camera is applied to observe and measure the spectrum of the X-ray attosecond pulses. This thesis first introduces the theory background of ultrafast lasers, then mainly explains high harmonic generation, which is the key method for attosecond pulses generation, subsequently presents the experiment system and analyzes the results from the experiment, also compares different combinations of parameters of ...


Investigating Compositional Variations Of S-Complex Near-Earth Asteroids: (1627) Ivar, Jenna Jones Jan 2018

Investigating Compositional Variations Of S-Complex Near-Earth Asteroids: (1627) Ivar, Jenna Jones

Electronic Theses and Dissertations

We seek to investigate the complexity and heterogeneity of the surfaces of near-Earth asteroids (NEAs). In particular, we are studying the S-complex NEAs, which account for a large portion of the observed near-Earth objects. Here we present our results for (1627) Ivar, an Amor class NEA with taxonomic type Sqw. In 2013, Ivar's large size and close approach to Earth (minimum distance 0.32 AU) provided an opportunity to observe the asteroid over many different viewing angles for an extended period of time. We collected delay-Doppler radar images and Doppler spectra using the Arecibo Observatory's 2380 MHz radar ...


Electronic, Optical, And Magnetic Properties Of Graphene And Single-Layer Transition Metal Dichalcogenides In The Presence Of Defects, Mahtab Khan Jan 2018

Electronic, Optical, And Magnetic Properties Of Graphene And Single-Layer Transition Metal Dichalcogenides In The Presence Of Defects, Mahtab Khan

Electronic Theses and Dissertations

Two-dimensional (2D) materials, such as graphene and single-layer (SL) transition metal dichalcogenides (TMDCs), have attracted a lot of attention due to their fascinating electronic and optical properties. Graphene was the first 2D material that has successfully been exfoliated from bulk graphite in 2004. In graphene, charge carriers interacting with the honeycomb lattice of carbon atoms of graphene to appear as massless Dirac fermions. Massless quasiparticles with linear dispersion are also observed in surface states of 3D topological insulators and quantum Hall edge states. My first project deals with the two-dimensional Hong-Ou-Mandel (HOM) type interference experiment for massless Dirac fermions in ...


Generation And Characterization Of Isolated Attosecond Pulse In The Soft X-Ray Regime, Jie Li Jan 2018

Generation And Characterization Of Isolated Attosecond Pulse In The Soft X-Ray Regime, Jie Li

Electronic Theses and Dissertations

The observation of any atomic and molecular dynamics requires a probe that has a timescale comparable to the dynamics itself. Ever since the invention of laser, the temporal duration of the laser pulse has been incrementally reduced from several nanoseconds to just attoseconds. Picosecond and femtosecond laser pulses have been widely used to study molecular rotation and vibration. In 2001, the first single isolated attosecond pulse (1 attosecond = 10^-18 seconds.) was demonstrated. Since this breakthrough, "attoscience" has become a hot topic in ultrafast physics. Attosecond pulses typically have span between EUV to X-ray photon energies and sub-femtosecond pulse duration ...


Tuning Chemical And Optical Properties Of Nanomaterials: From Extended Surfaces To Finite Nanoclusters, Zahra Hooshmand Gharehbagh Jan 2018

Tuning Chemical And Optical Properties Of Nanomaterials: From Extended Surfaces To Finite Nanoclusters, Zahra Hooshmand Gharehbagh

Electronic Theses and Dissertations

Modifying the electronic and optical properties of surfaces and nanostructures are in the forefront of surface science. This dissertation's focus is on this problem. The first part is on the adsorption of functionalized naphthalene molecules on Cu(111) surface. The results show that changing the functional group results in modification of charge redistribution at the interface of molecule and surface and the electronic structure of Cu changes. The second part discusses the new Moire structure of h-BN on Rh(111) induced by intrinsic carbon impurities of Rh single crystals. We found that these impurities intercalate between h-BN and Rh ...


Resonant Anisotropic Emission In Rabbitt Spectroscopy, Bejan M. Ghomashi Jan 2018

Resonant Anisotropic Emission In Rabbitt Spectroscopy, Bejan M. Ghomashi

Honors Undergraduate Theses

A variant of RABBITT pump-probe spectroscopy in which the attosecond pulse train comprises both even and odd harmonics of the fundamental IR probe frequency is explored to measure time-resolved photoelectron emission in systems that exhibit autoionizing states. It is shown that the group delay of both one-photon and two-photon resonant transitions is directly encoded in the energy-resolved photoelectron anisotropy as a function of the pump-probe time-delay. This principle is illustrated for a 1D model with symmetric zero-range potentials that supports both bound states and shape-resonances. The model is studied using both perturbation theory and solving the time-dependent Schodinger equation on ...


Nonlinear Dynamics In Multimode Optical Fibers, Mohammad Amin Eftekhar Jan 2018

Nonlinear Dynamics In Multimode Optical Fibers, Mohammad Amin Eftekhar

Electronic Theses and Dissertations

Multimode optical fibers have recently reemerged as a viable platform for addressing a number of long-standing issues associated with information bandwidth requirements and power-handling capabilities. The complex nature of heavily multimoded systems can be effectively exploited to observe altogether novel physical effects arising from spatiotemporal and intermodal linear and nonlinear processes. Here, we have studied nonlinear dynamics in multimode optical fibers (MMFs) in both the normal and anomalous dispersion regimes. In the anomalous dispersion regime, the nonlinearity leads to a formation of spatiotemporal 3-D solitons. Unlike in single-mode fibers, these solitons are not unique and their properties can be modified ...


Mathematical Foundations Of Adaptive Quantum Processing, Daniel Bonior Jan 2018

Mathematical Foundations Of Adaptive Quantum Processing, Daniel Bonior

Electronic Theses and Dissertations

Quantum information has the potential to revolutionize the way we store, process, transfer and acquire information [1,14,15,21,37]. In particular, quantum information offers exciting new approaches to secure communication, computation and sensing. However, in order to realize such technologies, we must first understand the effect that environmental noise has on a quantum system. This dissertation builds upon recent studies that have explored the underlying structure of quantum information and the effects of qubit channels in quantum communication protocols. This work is divided into five main chapters, with Chapter 1 being a brief introduction to quantum information. We ...


Thin-Film Lithium Niobate Photonics For Electro-Optics, Nonlinear Optics, And Quantum Optics On Silicon, Ashutosh Rao Jan 2018

Thin-Film Lithium Niobate Photonics For Electro-Optics, Nonlinear Optics, And Quantum Optics On Silicon, Ashutosh Rao

Electronic Theses and Dissertations

Ion-sliced thin-film lithium niobate (LN) compact waveguide technology has facilitated the resurgence of integrated photonics based on lithium niobate. These thin-film LN waveguides offer over an order of magnitude improvement in optical confinement, and about two orders of magnitude reduction in waveguide bending radius, compared to conventional LN waveguides. Harnessing the improved confinement, a variety of miniaturized and efficient photonic devices are demonstrated in this work. First, two types of compact electrooptic modulators are presented – microring modulators, and Mach-Zehnder modulators. Next, two distinct approaches to nonlinear optical frequency converters are implemented – periodically poled lithium niobate, and mode shape modulation (grating ...


From Excited Charge Dynamics To Cluster Diffusion: Development And Application Of Techniques Beyond Dft And Kmc, Shree Ram Acharya Jan 2018

From Excited Charge Dynamics To Cluster Diffusion: Development And Application Of Techniques Beyond Dft And Kmc, Shree Ram Acharya

Electronic Theses and Dissertations

This dissertation focuses on developing reliable and accurate computational techniques which enable the examination of static and dynamic properties of various activated phenomena using deterministic and stochastic approaches. To explore ultrafast electron dynamics in materials with strong electron-electron correlation, under the influence of a laser pulse, an ab initio electronic structure method based on time-dependent density functional theory (TDDFT) in combination with dynamical mean field theory (DMFT) is developed and applied to: 1) single-band Hubbard model; 2) multi-band metal Ni; and 3) multi-band insulator MnO. The ultrafast demagnetization in Ni reveal the importance of memory and correlation effects, leading to ...


Impact Of Ionizing Radiation And Electron Injection On Carrier Transport Properties In Narrow And Wide Bandgap Semiconductors, Jonathan Lee Jan 2018

Impact Of Ionizing Radiation And Electron Injection On Carrier Transport Properties In Narrow And Wide Bandgap Semiconductors, Jonathan Lee

Electronic Theses and Dissertations

This study investigated the minority carrier properties of wide and narrow bandgap semiconductors. Included specifically are wide bandgap materials GaN and β-Ga2O3, and narrow bandgap InAs/GaSb type-II strain-layer superlattice. The importance of minority carrier behavior in bipolar device performance is utmost because it is the limiting component in current conduction. The techniques used to determine minority carrier properties include electron beam induced current (EBIC) and cathodoluminescence (CL) spectroscopy. The CL spectroscopy is complemented with time-resolved CL (TRCL) for direct measurement of carrier radiative recombination lifetime. The minority carrier properties and effect of high energy radiation is explored. The GaN ...


Non-Hermitian Optics, Absar Ulhassan Jan 2018

Non-Hermitian Optics, Absar Ulhassan

Electronic Theses and Dissertations

From the viewpoint of quantum mechanics, a system must always be Hermitian since all its corresponding eigenvalues must be real. In contrast, the eigenvalues of open systems-unrestrained because of either decay or amplification-can be in general complex. Not so long ago, a certain class of non-Hermitian Hamiltonians was discovered that could have a completely real eigenvalue spectrum. This special class of Hamiltonians was found to respect the property of commutation with the parity-time (PT) operator. Translated into optics, this implies a balance between regions exhibiting gain and loss. Traditionally, loss has been perceived as a foe in optics and something ...


Undergraduate Student Agreement With Reformed Introductory Physics Classes, Matthew Wilcox Jan 2018

Undergraduate Student Agreement With Reformed Introductory Physics Classes, Matthew Wilcox

Electronic Theses and Dissertations

In this study, I investigate student "buy-in", defined as students' proper understanding of and agreement with the class format, for introductory studio physics classes that incorporate lectures, labs, and group problem-solving activities into one interactive environment. I also investigate the ways in which instructors try to gain student buy-in to their class. Research has shown that student resistance to reformed instruction is a barrier to an instructor's use of research-based instructional strategies that are common to the studio class. Expectancy value theory suggests that by gaining student buy-in to the reformed class format, student resistance will decrease thus allowing ...


The Subject Librarian Newsletter, Physics, Spring 2017, Sandy Avila Jan 2017

The Subject Librarian Newsletter, Physics, Spring 2017, Sandy Avila

Libraries' Newsletters

No abstract provided.


Mesoscopic Interactions In Complex Photonic Media, Roxana Rezvani Naraghi Jan 2017

Mesoscopic Interactions In Complex Photonic Media, Roxana Rezvani Naraghi

Electronic Theses and Dissertations

Mesoscale optics provides a framework for understanding a wide range of phenomena occurring in a variety of fields ranging from biological tissues to composite materials and from colloidal physics to fabricated nanostructures. When light interacts with a complex system, the outcome depends significantly on the length and time scales of interaction. Mesoscale optics offers the apparatus necessary for describing specific manifestations of wave phenomena such as interference and phase memory in complex media. In-depth understanding of mesoscale phenomena provides the required quantitative explanations that neither microscopic nor macroscopic models of light-matter interaction can afford. Modeling mesoscopic systems is challenging because ...


Computational Approach To Electrocatalysis, Nagendra Dhakal Jan 2017

Computational Approach To Electrocatalysis, Nagendra Dhakal

Electronic Theses and Dissertations

The main objective of this work is to understand the theoretical basis of the working principle of the Hydrogen fuel cell. We seek the physical basis of the Rational Design Technique, the smart way of preselecting materials from the material-pool, implemented in our study anticipating highly promising electrocatalysts for promoting the conversion of chemical energy stored in hydrogen molecules into the electrical energy. It needs the understanding of the relationship among the compositions of the materials under consideration, their electronic structure and catalytic activities. We performed the first principle DFT calculations to achieve the goal. Our work is focused first ...


Design And Verification Of A Multi-Terawatt Ti-Sapphire Femtosecond Laser System, Patrick Roumayah Jan 2017

Design And Verification Of A Multi-Terawatt Ti-Sapphire Femtosecond Laser System, Patrick Roumayah

Electronic Theses and Dissertations

Ultrashort pulse lasers are well-established in the scientific community due to the wide range of applications facilitated by their extreme intensities and broad bandwidth capabilities. This thesis will primarily present the design for the Mobile Ultrafast High Energy Laser Facility (MU-HELF) for use in outdoor atmospheric propagation experiments under development at the Laser Plasma Laboratory at UCF. The system is a 100fs 500 mJ Ti-Sapphire Chirped-Pulse Amplification (CPA) laser, operating at 10 Hz. Some background on the generation of very high intensity optical pulses is also presented, alongside an overview of the physics of filamentation. As part of the design ...


The Consequences Of A Reduced Superlattice Thickness On Quantum Cascade Laser Performance, Pedro Figueiredo Jan 2017

The Consequences Of A Reduced Superlattice Thickness On Quantum Cascade Laser Performance, Pedro Figueiredo

Electronic Theses and Dissertations

Coherent infrared radiation sources are essential for the operability of a wide range of scientific, industrial, military and commercial systems. The importance of the mid-infrared spectral region cannot be understated. Numerous molecules have some vibrational band in this range, allowing for identification of species by means of absorption, emission or some other form of spectroscopy. As such, spectroscopy alone has numerous applications ranging from industrial process control to disease diagnosis utilizing breath analysis. However, despite the discovery of the LASER in the 60s, to this day the amount of coherent sources in this range is limited. It is for this ...