Physics Commons^™

Geometries In Soft Matter, Zhenwei Yao

Physics - Dissertations

No abstract provided.

Transport And Spectroscopic Studies Of The Effects Of Fullerene Structure On The Efficiency And Lifetime Of Polythiophene-Based Solar Cells, Emilee L. Sena, Justin H. Peel, Devin Wesenberg, Shreya Nathan, Marianne Wallis, Maxwell J. Giammona, Thorsteinn Adalsteinsson, Brian J. Mcnelis, Richard P. Barber Jr.

Physics

Time-dependent measurements of both power conversion efficiency and ultraviolet-visible absorption spectroscopy have been observed for solar cell blends containing the polymer poly(3-hexylthiophene-2,5-diyl) (P3HT) with two different functionalized C60 electron acceptor molecules: commercially available [6,6]-phenyl C61 butyric acid methyl ester (PCBM) or [6,6]-phenyl C61 butyric acid octadecyl ester (PCBOD) produced in this laboratory. Efficiency was found to decay with an exponential time dependence, while spectroscopic features show saturating exponential behavior. Time constants extracted from both types of measurements showed reasonable agreement for samples produced from the same blend. In comparison to the PCBM samples, the stability of the PCBOD blends was …

Delphi: A Comprehensive Suite For Delphi Software And Associated Resources, Lin Li, Chuan Li, Subhra Sarkar, Jie Zhang, Shawn Witham, Zhe Zhang, Lin Wang, Nicholas Smith, Marharyta Petukh, Emil Alexov

Publications

Background

Accurate modeling of electrostatic potential and corresponding energies becomes increasingly important for understanding properties of biological macromolecules and their complexes. However, this is not an easy task due to the irregular shape of biological entities and the presence of water and mobile ions.

Results

Here we report a comprehensive suite for the well-known Poisson-Boltzmann solver, DelPhi, enriched with additional features to facilitate DelPhi usage. The suite allows for easy download of both DelPhi executable files and source code along with a makefile for local installations. The users can obtain the DelPhi manual and parameter files required for the corresponding …

The Quantum Mechanics Of Supersymmetry, Joshua Gearhart

Physics

No abstract provided.

Building And Characterization Of Laser Diodes As Well As System Design Of A Dual Wavelength Fabry-Perot Interferometer, Nicholas Czapla

Physics

No abstract provided.

Evaluation Of The Temperature Dependence Of Endurance Models Of Electrostatic Breakdown, Charlie Sim, Jr Dennison

Senior Theses and Projects

The goal of this research was to investigate temperature and time dependent models for the electrostatic breakdown of polymeric spacecraft insulators. Temperature dependent breakdown was found by inducing an electrostatic breakdown in the prototypical polymer Low Density Polyethylene (LDPE) at various temperatures. Time dependent breakdown was found by applying a static voltage to LDPE and measuring the time to electrostatic breakdown. No significant temperature dependence of the electrostatic breakdown of LDPE was observed in a temperature range of 150 K to 300 K. The time dependent results show that the time to electrostatic breakdown is modeled by a negative logarithmic …

Search For Gravitational Waves From Intermediate Mass Binary Black Holes, J. Abadie, Marco Cavaglia, For Full List Of Authors, See Publisher's Website.

Physics Faculty Research & Creative Works

We present the results of a weakly modeled burst search for gravitational waves from mergers of nonspinning intermediate mass black holes in the total mass range 100-450M_⊙ and with the component mass ratios between 1:1 and 4:1. The search was conducted on data collected by the LIGO and Virgo detectors between November of 2005 and October of 2007. No plausible signals were observed by the search which constrains the astrophysical rates of the intermediate mass black holes mergers as a function of the component masses. In the most efficiently detected bin centered on 88 + 88 M_⊙, …

The Effects Of Surface Roughness On Diffuse Optical Reflection And Photoyields On Spacecraft Materials, Amberly Evans Jensen

Senior Theses and Projects

The goal of this project was to measure the change in the absorbance of spacecraft materials due to changes in the surface of the material. The absorbance was obtained by measuring reflectance and transmittance. We found that modifying the surface of a material did affect the material’s specular reflectance. However, the change may not have been entirely due to an increase in absorbance, but may also imply an increase in the diffuse reflection. To understand the affect on absorbance, diffuse reflectance and transmission will need to be measured. This will lead to a prediction of how surface modification affects the …

Differential Cross Sections For Top-Pair And Single-Top Production, Nikolaos Kidonakis

Faculty and Research Publications

I present theoretical results at approximate NNLO from NNLL resummation for top quark production at the LHC and the Tevatron, including new results at 8 TeV LHC energy. Total cross sections are shown for tt¯ production, for single top production in the t and s channels and via associated tW production, and for associated tH− production. Top quark transverse momentum and rapidity distributions in tt¯production are also presented, as well as new results for t-channel single top and single antitop pT distributions.

Real Time Shrinkage Studies In Photopolymer Films Using Holographic Interferometry, Mohesh Moothanchery, Izabela Naydenova, Viswanath Bavigadda, Suzanne Martin, Vincent Toal

Conference Papers

Polymerisation induced shrinkage is one of the main reasons why photopolymer materials are not more widely used for holographic applications. The aim of this study is to evaluate the shrinkage in an acrylamide photopolymer layer during holographic recording using holographic interferometry. Shrinkage in photopolymer layers can be measured by real time capture of holographic interferograms during holographic recording. Interferograms were captured using a CMOS camera at regular intervals. The optical path length change and hence the shrinkage were determined from the captured fringe patterns. It was observed that the photopolymer layer shrinkage is in the order of 3.5%.

Insulator-To-Metal Transition And Correlated Metallic State Of V 2 O 3 Investigated By Optical Spectroscopy, M. K. Stewart, D. Brownstead, (...), M. M. Qazilbash, Et Al.

Arts & Sciences Articles

The optical properties of V2O3 thin films are investigated across the insulator-to-metal transition and in the metallic state. The spectral weight transfer observed across the transition, over an energy scale of 5 eV, is consistent with the Mott-Hubbard model for correlated electron systems. In the metallic phase, a strong Drude peak is observed, which exhibits a pronounced temperature dependence related to the transfer of states from the Hubbard bands to the quasiparticle peaks as the temperature is reduced. The analysis of the far-infrared spectra reveals signatures of strong electronic correlations in V2O3. Finally, a comparison to VO2 data is presented.

Mott Transition And Electronic Structure In Complex Oxide Heterostructures, Jian Liu

Graduate Theses and Dissertations

Strongly correlated electron systems, particularly transition metal oxides, have been a focus of condensed matter physics for more than two decades since the discovery of high-temperature superconducting cuprates. Diverse competing phases emerge, spanning from exotic magnetism to unconventional superconductivity, in proximity to the localized-itinerant transition of Mott insulators. While studies were concentrated on bulk crystals, the recent rapid advance in synthesis has enabled fabrication of high-quality oxide heterostructures, offering a new route to create novel artificial quantum materials.

This dissertation details the investigation on ultrathin films and heterostructures of 3d⁷(t_2g⁶e_g¹) systems with …

Hybrid Nanostructures For Artificial Machine Olfaction, Landon Joseph Oakes

Masters Theses & Specialist Projects

The detection of low level concentrations of particles in a gaseous environment is of importance to many fields, especially Homeland Security. The ability to identify ppb concentrations of explosives and their degradation products can aid in the detection of improvised explosive devices (IEDs), ammunition dumps, or hidden explosives. One method of accomplishing this task is through the use of an array of chemiresistors in an electronic nose device. For this study, chemiresistors were constructed using 3-D silica nanospring mats with a contiguous film of ZnO nanocrystals and ZnO nanocrystals decorated by metallic nanoparticles. Samples with an average grain size of …

Use Of Ultra High Vacuum Plasma Enhanced Chemical Vapor Deposition For Graphene Fabrication, Shannen Adcock

Graduate Theses and Dissertations

Graphene, what some are terming the "new silicon", has the possibility of revolutionizing technology through nanoscale design processes. Fabrication of graphene for device processing is limited largely by the temperatures used in conventional deposition. High temperatures are detrimental to device design where many different materials may be present. For this reason, graphene synthesis at low temperatures using plasma-enhanced chemical vapor deposition is the subject of much research. In this thesis, a tool for ultra-high vacuum plasma-enhanced chemical vapor deposition (UHV-PECVD) and accompanying subsystems, such as control systems and alarms, are designed and implemented to be used in future graphene growths. …

First Low-Latency Ligo+Virgo Search For Binary Inspirals And Their Electromagnetic Counterparts, J. Abadie, Marco Cavaglia, For Full List Of Authors, See Publisher's Website.

Physics Faculty Research & Creative Works

Aims. The detection and measurement of gravitational-waves from coalescing neutron-star binary systems is an important science goal for ground-based gravitational-wave detectors. In addition to emitting gravitational-waves at frequencies that span the most sensitive bands of the LIGO and Virgo detectors, these sources are also amongst the most likely to produce an electromagnetic counterpart to the gravitational-wave emission. A joint detection of the gravitational-wave and electromagnetic signals would provide a powerful new probe for astronomy. Methods. During the period between September 19 and October 20, 2010, the first low-latency search for gravitational-waves from binary inspirals in LIGO and Virgo data was …

Effects Of Long-Range Tip-Sample Interaction On Magnetic Force Imaging: A Comparative Study Between Bimorph Driven System And Electrostatic Force Modulation, Byung I. Kim

Physics Faculty Publications and Presentations

Magnetic force microscopy (MFM) using electrostatic force modulation has been designed and developed to avoid the drawbacks of the bimorph driven system. The bimorph driven system has poor frequency response and overlap of the topographic features on magnetic structures of the MFM images. In the electrostatic force modulation system, the amplitude increases in the noncontact regime as the tip approaches due to the capacitive coupling between tip and sample. MFM using electrostatic force modulation has been applied to observe maze-like stripe domain structures on a CoCr film. The contrast mechanism and imaging stability of MFM using electrostatic force modulation are …

Finite-Difference Time-Domain Modeling Of Nickel Nanorods, Joseph Steele Parris

Theses and Dissertations

Theoretical and experimental plasmonics is a growing field as a method to create near fields at sub-wavelength distances. In this thesis, a finite-difference time-domain method is used to simulate electromagnetic waves onto a thin film that present of nickel nanorods with sharp apexes. The absorbed, transmitted, and reflected fields were shown to depend linearly on silver film thickness and nanotip length. The electric field is visualized along the tip to show strong charge density along the base of the tip’s apex and how that density changes for wavelength, metal, and source tilt. Lastly, the study shows gold film on the …

Coupled-Channel Theory Of Photoionization Microscopy, L. B. Zhao, I. I. Fabrikant, John B. Delos, F. Lepine, S. Cohen, C. Bordas

Arts & Sciences Articles

We develop a quantum-mechanical coupled-channel theory to simulate spatial distributions of electron current densities, produced in photoionization for nonhydrogenic atoms in the presence of a uniform external electric field. The coupled Schrodinger equations are numerically solved using the renormalized Numerov method. The expression for the outgoing wave function for photoelectrons ejected from the nonhydrogenic atomic source is derived. The theory is applied to investigations of photoionization for ground-state Li atoms. The distributions of electron current densities are computed and compared to the corresponding experimental images. Excellent agreement is obtained. It is, furthermore, found that the presence of the nonhydrogenic residual …

Differential And Total Cross Sections For Top Pair And Single Top Production, Nikolaos Kidonakis

Faculty and Research Publications

I present theoretical results at approximate NNLO from NNLL resummation for top quark production at the LHC and the Tevatron, including new results at 8 TeV LHC energy. Total cross sections are shown for tt¯ production, for single top production in the t and s channels and via associated tW production, and for associated tH− production. Top quark transverse momentum and rapidity distributions in tt¯production are also presented, as well as new results for t-channel single top and single antitop pT distributions.

Time Dependence Of Bathymetric Effects On Hurricane Storm Surge, Christopher Dupuis

Honors Theses

No abstract provided.