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Control Of Spontanous Emission From Quantum Emitters Using Hyperbolic Metamaterial Substrates, Tal Galfsky 2016 The Graduate Center, City University of New York

Control Of Spontanous Emission From Quantum Emitters Using Hyperbolic Metamaterial Substrates, Tal Galfsky

All Graduate Works by Year: Dissertations, Theses, and Capstone Projects

Hyperbolic metamaterials (HMMs) are so named for possessing a hyperboloid-shaped dispersion which gives rise to a large photonic density of states. Quantum emitters placed inside or in the near-field of a HMM have been shown to exhibit strong enhancement of spontaneous emission due to the increase in available states. This thesis focuses on enhancing spontaneous emission of quantum emitters in optical frequencies by utilizing multilayered metal/dielectric composites that form these highly anisotropic metamaterials. In conjunction with the enhanced decay rate we experimentally demonstrate two methods for shaping and directing radiation trapped in the HMM into free space by employing ...


Imaging Population Transfer In Atoms With Ultrafast Electron Pulses, Hua-Chieh Shao, Anthony F. Starace 2016 Purdue University

Imaging Population Transfer In Atoms With Ultrafast Electron Pulses, Hua-Chieh Shao, Anthony F. Starace

Anthony F. Starace Publications

We propose the use of ultrafast electron diffraction (UED) to image a controllable, laser-driven coherent electron population transfer in lithium atoms with currently available femtosecond electron pulses. Our simulations demonstrate the ability of ultrafast electrons to image such an electronic population transfer, thus validating UED as a direct means of investigating electron dynamics. Provided the incident electron pulses have sufficient temporal resolution, the diffraction images are shown to resolve also the relative phases of the target electronic wave functions.


Enhancement Of Hopping Conductivity By Spontaneous Fractal Ordering Of Low-Energy Sites, Tianran Chen, Brian Skinner 2016 West Chester University of Pennsylvania

Enhancement Of Hopping Conductivity By Spontaneous Fractal Ordering Of Low-Energy Sites, Tianran Chen, Brian Skinner

Physics

Variable-range hopping conductivity has long been understood in terms of a canonical prescription for relating the single-particle density of states to the temperature-dependent conductivity. Here we demonstrate that this prescription breaks down in situations where a large and long-ranged random potential develops. In particular, we examine a canonical model of a completely compensated semiconductor, and we show that at low temperatures hopping proceeds along self-organized, low-dimensional subspaces having fractal dimension d = 2. We derive and study numerically the spatial structure of these subspaces, as well as the conductivity and density of states that result from them. One of our prominent ...


Infrared Skin Damage Thresholds From 1319-Nm Continous-Wave Laser Exposures, Gavin D. Buffington, Clifton D. Clark 2016 Fort Hays State University

Infrared Skin Damage Thresholds From 1319-Nm Continous-Wave Laser Exposures, Gavin D. Buffington, Clifton D. Clark

Gavin Buffington

A series of experiments were conducted in vivo using Yucatan miniature pigs (Sus scrofa domestica) to determine thermal damage thresholds to the skin from 1319-nm continuous-wave Nd:YAG laser irradiation. Experiments employed exposure durations of 0.25, 1.0, 2.5, and 10 s and beam diameters of ∼0.6 and 1 cm. Thermal imagery data provided a time-dependent surface temperature response from the laser. A damage endpoint of fifty percent probability of a minimally visible effect was used to determine threshold for damage at 1 and 24 h postexposure. Predicted thermal response and damage thresholds are compared with a ...


Infrared Skin Damage Thresholds From 1319-Nm Continous-Wave Laser Exposures, Gavin D. Buffington, Clifton D. Clark 2016 Fort Hays State University

Infrared Skin Damage Thresholds From 1319-Nm Continous-Wave Laser Exposures, Gavin D. Buffington, Clifton D. Clark

Clifton D. Clark

A series of experiments were conducted in vivo using Yucatan miniature pigs (Sus scrofa domestica) to determine thermal damage thresholds to the skin from 1319-nm continuous-wave Nd:YAG laser irradiation. Experiments employed exposure durations of 0.25, 1.0, 2.5, and 10 s and beam diameters of ∼0.6 and 1 cm. Thermal imagery data provided a time-dependent surface temperature response from the laser. A damage endpoint of fifty percent probability of a minimally visible effect was used to determine threshold for damage at 1 and 24 h postexposure. Predicted thermal response and damage thresholds are compared with a ...


Fractional Charge Methods For Correcting Approximate Kohn-Sham Potentials, Darya N. Komsa 2016 The University of Western Ontario

Fractional Charge Methods For Correcting Approximate Kohn-Sham Potentials, Darya N. Komsa

Electronic Thesis and Dissertation Repository

The Kohn-Sham density functional theory relies on approximating the exchange-correlation energy functional or the corresponding potential. The behavior of the exchange-correlation potential as a function of position in a system can be used to detect and correct deficiencies of the parent functional. The too-fast decay of the potentials derived from common density functionals is a major problem, because it causes inaccurate Rydberg excitation energies and erroneous fractional charges in dissociating molecules. An efficient method to correct the shape of the exchange-correlation potential was proposed by Gaiduk et al. [A. P. Gaiduk, D. S. Firaha, and V. N. Staroverov, Phys. Rev ...


Photonicstd-2d: Modeling Light Scattering In Periodic Multilayer Photonic Structures, Alexey Bondarev, Shaimaa Azzam, Zhaxylyk Kudyshev, Alexander V. Kildishev 2016 North Carolina State University at Raleigh

Photonicstd-2d: Modeling Light Scattering In Periodic Multilayer Photonic Structures, Alexey Bondarev, Shaimaa Azzam, Zhaxylyk Kudyshev, Alexander V. Kildishev

The Summer Undergraduate Research Fellowship (SURF) Symposium

Efficient modeling of electromagnetic processes in optical and plasmonic metamaterials is important for enabling new and exciting ways to manipulate light for advanced applications. In this work, we put together a tool for numerical simulation of propagation of normally incident light through a nanostructured multilayer composite material. The user builds a unit cell of a given material layer-by-layer starting from a substrate up to a superstrate, splitting each layer further into segments. The segments are defined by width and material -- dielectric, metal or active medium. Simulations are performed with the finite difference time domain (FDTD) method. A database of common ...


Hyperpolarized 3he Magnetic Resonance Imaging Phenotypes Of Chronic Obstructive Pulmonary Disease, Damien Pike 2016 The University of Western Ontario

Hyperpolarized 3he Magnetic Resonance Imaging Phenotypes Of Chronic Obstructive Pulmonary Disease, Damien Pike

Electronic Thesis and Dissertation Repository

Chronic obstructive pulmonary disease (COPD) is the third leading cause of death in the world. Identifying clinically relevant COPD phenotypes has the potential to reduce the global burden of COPD by helping to alleviate symptoms, slow disease progression and prevent exacerbation by stratifying patient cohorts and forming targeted treatment plans. In this regard, quantitative pulmonary imaging with hyperpolarized 3He magnetic resonance imaging (MRI) and thoracic computed tomography (CT) have emerged as ways to identify and measure biomarkers of lung structure and function. 3He MRI may be used as a tool to probe both functional and structural properties of the lung ...


Observations Of High Vibrational Levels Of The 4fσ 41Σ+ U State Of H2, Alexander M. Chartrand, Robert C. Ekey Jr., Elizabeth F. McCormack 2016 Bryn Mawr College

Observations Of High Vibrational Levels Of The 4fσ 41Σ+ U State Of H2, Alexander M. Chartrand, Robert C. Ekey Jr., Elizabeth F. Mccormack

Physics Faculty Research and Scholarship

Resonantly enhanced multiphoton ionization via the EF 1Σg+, v′ = 6 double-well state has been used to probe the energy region below the third dissociation limit of H2 where several high vibrational levels of the 41Σu+ state are expected. Theoretical ab initio potential energy curves for this state predict a deep inner well and shallow outer well where vibrational levels above v = 8 are expected to exhibit the double-well character of the state. Since the 41Σu+ state has f-state character, transitions to it from the ground state are nominally forbidden. However ...


Multistart Spiral Electron Vortices In Ionization By Circularly Polarized Uv Pulses, Jean Marcel Ngoko Djiokap, Alexei V. Meremianin, N. L. Manakov, S. X. Hu, L. B. Madsen, Anthony F. Starace 2016 University of Nebraska-Lincoln

Multistart Spiral Electron Vortices In Ionization By Circularly Polarized Uv Pulses, Jean Marcel Ngoko Djiokap, Alexei V. Meremianin, N. L. Manakov, S. X. Hu, L. B. Madsen, Anthony F. Starace

Anthony F. Starace Publications

Multistart spiral vortex patterns are predicted for the electron momentum distributions in the polarization plane following ionization of the helium atom by two time-delayed circularly polarized ultrashort laser pulses. For two ultraviolet (UV) pulses having the same frequency (such that two photons are required for ionization), single-color two-photon interferometry with corotating or counter-rotating time-delayed pulses is found to lead respectively to zero-start or four-start spiral vortex patterns in the ionized electron momentum distributions in the polarization plane. In contrast, two-color one-photon plus two-photon interferometry with time-delayed corotating or counter-rotating UV pulses is found to lead respectively to one ...


Theoretical Analysis Of Single Molecule Spectroscopy Lineshapes Of Conjugated Polymers, Murali Devi 2016 Graduate Center, City University of New York

Theoretical Analysis Of Single Molecule Spectroscopy Lineshapes Of Conjugated Polymers, Murali Devi

All Graduate Works by Year: Dissertations, Theses, and Capstone Projects

Conjugated Polymers(CPs) exhibit a wide range of highly tunable optical properties. Quantitative and detailed understanding of the nature of excitons responsible for such a rich optical behavior has significant implications for better utilization of CPs for more efficient plastic solar cells and other novel optoelectronic devices. In general, samples of CPs are plagued with substantial inhomogeneous broadening due to various sources of disorder. Single molecule emission spectroscopy (SMES) offers a unique opportunity to investigate the energetics and dynamics of excitons and their interactions with phonon modes. The major subject of the present thesis is to analyze and understand room ...


Model For The Electrolysis Of Water And Its Use For Optimization, Roger Lascorz, Javier E. Hasbun Dr 2016 Georgia Institute of Technology

Model For The Electrolysis Of Water And Its Use For Optimization, Roger Lascorz, Javier E. Hasbun Dr

Georgia Journal of Science

The goal of this research was to study the optimization of the electrolysis of water both theoretically and experimentally. For accuracy, 3 hr experiments were made with measurements recorded every 15 min. The results show that a better model than the classical one is needed for water electrolysis. A new model that fits experimental data better is proposed. The results of this new model not only predict hydrogen production in electrolysis of water better, but show a way to predict gas production of any liquid as well as what voltage to use to optimize it.


Dissociative Excitation Of H2 In An Rf Plasma, John Carlson 2016 Macalester College

Dissociative Excitation Of H2 In An Rf Plasma, John Carlson

Macalester Journal of Physics and Astronomy

Plasma-enhanced chemical vapor deposition is a widely used method for depositing thin films. In order to optimize the properties of the films, it is important to understand the plasma processes that occur during film growth. In this research we use optical emission spectroscopy in order to measure the spectral emission lines of a plasma produced with hydrogen gas. In conjunction with other measurements and modeling, these measurements can provide insight to the electron energy distribution of the plasma.


Numerical Simulations Of High-Dimensional Mode-Coupling Models In Molecular Dynamics, Kyle Lewis Liss 2016 Dickinson College

Numerical Simulations Of High-Dimensional Mode-Coupling Models In Molecular Dynamics, Kyle Lewis Liss

Honors Theses By Year

A fundamental question in molecular dynamics is the following: Given some bond-localized excitation of a molecule, what will be the pathway and rate of energy ow throughout the molecule's various degrees of freedom? This notion of vibrational energy transfer throughout a molecule is referred to as intramolecular vibrational redistribution (IVR) and has been a long-standing subject of interest in physical chemistry. Historically, IVR has been studied on a case-by-case basis. However, the essence of IVR for any molecular system is an anharmonic potential energy surface that causes dynamics in which the system's many degrees of freedom are coupled ...


A Cylindrically Symmetric “Micro-Mott” Electron Polarimeter, Nathan B. Clayburn, Evan M. Brunkow, S. J. Burtwistle, George H. Rutherford, Timothy J. Gay 2016 University of Nebraska - Lincoln

A Cylindrically Symmetric “Micro-Mott” Electron Polarimeter, Nathan B. Clayburn, Evan M. Brunkow, S. J. Burtwistle, George H. Rutherford, Timothy J. Gay

Timothy J. Gay Publications

A small, novel, cylindrically symmetric Mott electron polarimeter is described. The effective Sherman function, Seff , or analyzing power, for 20 kV Au target bias with a 1.3 keV energy loss window is 0.16 ± 0.01, where uncertainty in the measurement is due primarily to uncertainty in the incident electron polarization. For an energy loss window of 0.5 keV, Seff reaches its maximum value of 0.24 ± 0.02. The device’s maximum efficiency, I/Io, defined as the detected count rate divided by the incident particle rate, is 3.7 ± 0.2 ...


Development Of A Digital Offset Laser Lock, Ian W. Hage 2016 College of William and Mary

Development Of A Digital Offset Laser Lock, Ian W. Hage

College of William & Mary Undergraduate Honors Theses

An offset laser lock is an optoelectronic system capable of stabilizing a laser's optical frequency to a variable offset from another stable laser's frequency. The lock system described in this report relies on a digital frequency comparison of the beat note of two lasers to determine and fix the frequency difference, or offset, between them. This thesis describes the construction of a configurable proportional-integral (PI) control circuit to regulate a laser's frequency based on the error signal generated by a digital comparison of the beat note frequency, as well as the integration of formerly unconnected circuit elements ...


Increasing Quantum Limited Sensitivity Of Interferometers Using Electromagnetically Induced Transparency, Hunter Blake Rew 2016 College of William and Mary

Increasing Quantum Limited Sensitivity Of Interferometers Using Electromagnetically Induced Transparency, Hunter Blake Rew

College of William & Mary Undergraduate Honors Theses

We explore the properties of electromagnetically induced transparency (EIT) and its applications as a frequency filter in the field of gravitational wave interferometry. Through modeling and simulation, we determine parameters for atom-light configurations of multi- state atoms which will theoretically allow for transmission frequencies and intensities of squeezed light in a range suitable for increasing sensitiviy levels in gravitational wave interferometers. This corresponds to contrasts greater than 50% and linewidths of 100 Hz or less. We produce EIT experimentally and characterize the distributions by fitting them to a generalized Lorentzian. The largest contrast observed is 3.9% with a linewidth ...


Improving Optical Gyroscope Sensitivity Using A Fast Light Regime, Owen R. Wolfe 2016 College of William and Mary

Improving Optical Gyroscope Sensitivity Using A Fast Light Regime, Owen R. Wolfe

College of William & Mary Undergraduate Honors Theses

Optical gyroscopes use Sagnac interferometry to make precise measurements of angular velocity. In- creased gyroscope sensitivity will allow for more accurate control of aerospace systems and allow for more precise measurements of the Earth's rotation. Severalfold improvements to optical gyroscope sensitivity were predicted for fast light regimes (ng < 1). We evaluated the feasibility of these improvements in the N-bar dual pump scheme in 87Rb vapor. We were able to modify the stimulated gyroscope response via tuning the experimental parameters. Gyroscope sensitivity was shown to be dependent on several parameters including pump power, pump detuning, and vapor density.


Spontaneous Parametric Down Conversion Of Photons Through Β-Barium Borate, Luke Horowitz 2016 California Polytechnic State University, San Luis Obispo

Spontaneous Parametric Down Conversion Of Photons Through Β-Barium Borate, Luke Horowitz

Physics

An apparatus for detecting pairs of entangled 405nm photons that have undergone Spontaneous Parametric Down Conversion through β-Barium Borate is described. By using avalanche photo-diodes to detect the low-intensity converted beam and a coincidence module to register coincident photons, it is possible to create an apparatus than can be used to perform quantum information experiments under a budget appropriate for an undergraduate physics lab.


A Case For Chiral Contributions To Nondipole Effects In Photoionization Using Linearly Polarized Soft X-~Rays, Kyle Patrick Bowen 2016 University of Nevada, Las Vegas

A Case For Chiral Contributions To Nondipole Effects In Photoionization Using Linearly Polarized Soft X-~Rays, Kyle Patrick Bowen

UNLV Theses, Dissertations, Professional Papers, and Capstones

Modelling angular distributions of photoelectrons requires making accurate approximations of both the incoming light and the behavior of bound electrons. The experimental determination of photoelectron angular distributions is crucial to the development of accurate theoretical models governing the light-matter interaction. To date, many models have relied upon the dipole approximation, which assumes a constant electric field as the source of ionization. Despite knowing that the dipole approximation would break down as photon energy increased, the precise limit was unclear. Over the past two decades, a strong case has been made that corrections to the dipole approximation are necessary for accurately ...


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