Physical Sciences and Mathematics Commons^™

Treatment Of A Ring With Periodic Atomic Placement Through Differential Geometry, Gregory Karjala, Lok Lew Yan Voon

Explorations – The Journal of Undergraduate Research, Scholarship and Creativity at Wright State

Most treatments of Bloch’s Theorem have relied on group theory or other mathematical methods for its proof. In this paper we give a derivation of the quantum number first proposed by Y.C Lee and Wei Z. Lee for the Benzene ring through the use of differential geometry. We also develop a Bloch style relationship relation for the benzene ring with an additional quantum number. Through this treatment we show the usefulness of differential geometry in the theorist’s toolkit when it comes to solid-state problems.

Saturation-Dependence Of Dispersion In Porous Media, B. Ghanbarian-Alavijeh, Thomas E. Skinner, Allen Hunt

Physics Faculty Publications

In this study, we develop a saturation-dependent treatment of dispersion in porous media using concepts from critical path analysis, cluster statistics of percolation, and fractal scaling of percolation clusters. We calculate spatial solute distributions as a function of time and calculate arrival time distributions as a function of system size. Our previous results correctly predict the range of observed dispersivity values over ten orders of magnitude in experimental length scale, but that theory contains no explicit dependence on porosity or relative saturation. This omission complicates comparisons with experimental results for dispersion, which are often conducted at saturation less than 1. …

Characterization Of Structured Nanomaterials Using Terahertz Frequency Radiation, Andrew Niklas

Andrew Niklas

Measurements that use terahertz frequency radiation to characterize materials are beneficial for scientists trying to determine the physical parameters that govern the interaction of electromagnetic waves and matter at those frequencies. Results will be presented of time domain terahertz spectroscopy measurements taken in forward and backward scattering directions from vertically aligned arrays of multi‐walled carbon nanotubes and thin films of perforated copper. The intent of this research is to both corroborate results from independent research groups conducting similar experiments and to further increase understanding in the scientific community with respect to carbon nanotube reflection phenomena at terahertz frequencies.

Magnetic Nanoparticles In Hyperthermia Treatment, Gregory Kozlowski

Special Session 5: Carbon and Oxide Based Nanostructured Materials (2012)

No abstract provided.

Ac Magnetic Heating Of Superparamagnetic Fe And Co Nanoparticles, Anna Lukawska, Zafrullah Jagoo, Gregory Kozlowski, Zafer Turgut, Hiroyuki Kosai, Alexander Sheets, Tyler Bixel, Andrew Wheatley, Pavel Abdulkin, Benjamin Knappett, Thomas Houlding, Volkan Degirmenci

Special Session 5: Carbon and Oxide Based Nanostructured Materials (2012)

No abstract provided.

Growth Of Graphene Architectures On Sic, John J. Boeckl, Weijie Lu, William C. Mitchel, Kurt G. Eyink, Howard Smith, Larry Grazulis, Gerry Landis, Said Elhamri

Special Session 5: Carbon and Oxide Based Nanostructured Materials (2012)

No abstract provided.

In-Situ Engineering Of Graphene With Electrons, Mark Ruemmeli

Special Session 5: Carbon and Oxide Based Nanostructured Materials (2012)

No abstract provided.

New Routes To Copper Nanocatalysts For Fine Chemical Synthesis, Pavel Abdulkin, Yanina Moglie, Faysal Benaskar, Volker Engels, Jan Meuldijk, Volker Hessel, Emiel J. M. Hensen, Miguel Yus, Jaap C. Schouten, Francisco Alonso, Andrew E. H. Wheatley

Special Session 5: Carbon and Oxide Based Nanostructured Materials (2012)

No abstract provided.

Properties Of Sbsi@Cnts And Sbsi Nanowires, Marian Nowak, Krzysztof Koziol, Gregory Kozlowski, Krystian Mistewicz, Marcin Jesionek

Special Session 5: Carbon and Oxide Based Nanostructured Materials (2012)

No abstract provided.

Extraordinary Optical Transmission And Extinction In A Terahertz Wire-Grid Polarizer, J. S. Cetnar, J. R. Middendorf, Elliott R. Brown

Physics Faculty Publications

A THz wire grid polarizer is simulated and demonstrated consisting of 40-μm periodic aluminum strips mounted on a polycarbonate substrate with a variable metal-to-gap ratio. Full-wave numerical simulations were performed from 100 GHz to 550 GHz predicting that the transmission in perpendicular (parallel) polarization is much higher (lower) than that predicted by geometric optics, leading to a very high extinction ratio of ∼60 dB between 100 and 550 GHz when the gaps become very small (<5 >μm). This behavior is confirmed qualitatively in experiments between 100 and 530 GHz where extinction ratios exceeding 40 dB are achieved. …

Stable Highly Conductive Zno Via Reduction Of Zn Vacancies, David C. Look, Timothy C. Droubay, Scott A. Chambers

Physics Faculty Publications

Growth of Ga-doped ZnO by pulsed laser deposition at 200 °C in an ambient of Ar and H₂produces a resistivity of 1.5 × 10⁻⁴ Ω-cm, stable to 500 °C. The resistivity can be further reduced to 1.2 × 10⁻⁴ Ω-cm by annealing on Zn foil, which reduces the compensating Zn-vacancy acceptor concentration N_A to 5 × 10¹⁹ cm⁻³, only 3% of the Ga-donor concentration N_D of 1.6 × 10²¹ cm⁻³, with N_D and N_A determined from a degenerate mobility theory. The plasmon-resonance wavelength is only 1060 …

A New Model For Mixing By Double-Diffusive Convection (Semi-Convection): I. The Conditions For Layer Formation, G. M. Mirouh, P. Garaud, S. Stellmach, Adrienne L. Traxler, T. S. Wood

Physics Faculty Publications

The process referred to as "semi-convection" in astrophysics and "double-diffusive convection in the diffusive regime" in Earth and planetary sciences occurs in stellar and planetary interiors in regions which are stable according to the Ledoux criterion but unstable according to the Schwarzschild criterion. In this series of papers, we analyze the results of an extensive suite of three-dimensional (3D) numerical simulations of the process, and ultimately propose a new 1D prescription for heat and compositional transport in this regime which can be used in stellar or planetary structure and evolution models. In a preliminary study of the phenomenon, Rosenblum et …

Analytical Chemical Sensing Using High Resolution Terahertz/Submillimeter Wave Spectroscopy, Benjamin L. Moran

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A highly sensitive and selective Terahertz gas sensor used to analyze a complex mixture of Volatile Organic Compounds (VOCs) has been developed. To best demonstrate analytical capabilities of a THz chemical sensor, we chose to perform analytical quantitative analysis of a certified gas mixture using a prototype gas phase chemical sensor that couples a commercial preconcentration system (Entech 7100A) to a custom high resolution THz spectrometer. A Method TO-14A certified mixture of thirty-nine VOCs was purchased. Twenty-six of the thirty-nine chemicals were identified as suitable for THz spectroscopic detection. The Entech 7100A system is designed and marketed as an inlet …

Model For Triggering Of Non-Volcanic Tremor By Earthquakes, Naum I. Gershenzon, Gust Bambakidis

Physics Faculty Publications

There is evidence of tremor triggering by seismic waves emanating from distant large earthquakes. The frequency content of both triggered and ambient tremor are largely identical, suggesting that this property does not depend directly on the nature of the source. We show here that the model of plate dynamics developed earlier by us is an appropriate tool for describing tremor triggering. In the framework of this model, tremor is an internal response of a fault to a failure triggered by external disturbances. The model predicts generation of radiation in a frequency range defined by the fault parameters. Thus, although the …

Broadband 180 Degree Universal Rotation Pulses For Nmr Spectroscopy Designed By Optimal Control, Thomas E. Skinner, Naum I. Gershenzon, Manoj Nimbalkar, Wolfgang Bermel, Burkhard Luy, Steffen J. Glaser

Physics Faculty Publications

Broadband inversion pulses that rotate all magnetization components 180 degrees about a given fixed axis are necessary for refocusing and mixing in high-resolution NMR spectroscopy. The relative merits of various methodologies for generating pulses suitable for broadband refocusing are considered. The de novo design of 180 degree universal rotation pulses using optimal control can provide improved performance compared to schemes which construct refocusing pulses as composites of existing pulses. The advantages of broadband universal rotation by optimized pulses (BURBOP) are most evident for pulse design that includes tolerance to RF inhomogeneity or miscalibration. We present new modifications of the optimal …

A Mems Photoacoustic Detector Of Terahertz Radiation For Chemical Sensing, Nathan E. Glauvitz, S. Blazevic, Ronald A. Coutu Jr., Michael N. Kistler, Ivan Medvedev, Douglas T. Petkie

Physics Faculty Publications

A piezoelectric Microelectromechanical system (MEMS) cantilever pressure sensor was designed, modeled, fabricated, and tested for sensing the photoacoustic response of gases to terahertz (THz) radiation. The sensing layers were comprised of three thin films; a lead zirconate titanate (PZT) piezoelectric layer sandwiched between two metal contact layers. The sensor materials were deposited on the silicon device layer of a silicon-on-insulator (SOI) wafer, which formed the physical structure of the cantilever. To release the cantilever, a hole was etched through the backside of the wafer and the buried oxide was removed with hydrofluoric acid. Devices were then tested in a custom …

Characterization Of Ceramic Matrix Composite Materials Using Millimeter-Wave Techniques, Matthew Lee Bischoff

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This thesis describes studies that were carried out on Ceramic Matrix Composite (CMC) materials. These materials were provided by the Air Force Research Laboratory for evaluation in the millimeter-wave frequency region with the goal of developing Non-Destructive Evaluation techniques. This thesis centers on describing the measured reflections from an Oxide/Oxide and SiC/SiNC CMC materials. Models were derived from the Fresnel equations to account for the reflected and transmitted waves in these materials. System models were developed to describe the power coupling of the spectra measured in three separate measurement systems. Using these models the complex index of refraction was determined …

Characterization Of Ceramic Composite Materials Using Terahertz Non-Destructive Evaluation Techniques, Lindsay Owens

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The characterization of defects such as rust, voids, etc. on materials and the analysis and prediction of strain and stress induced breakdown are well known applications of non-destructive evaluation (NDE) techniques. THz radiation has been suggested as an effective NDE tool for use in the field of ceramics and ceramic matrix composite materials (CMC), via THz spectroscopy and imaging. The goal of this research is to monitor the progression of thermal and mechanical damage applied to the CMC materials using terahertz spectroscopic imaging in order to create a predictive model that will correlate THz imaging data of these materials to …

Terahertz Time Domain Spectroscopy And Fresnel Coefficient Based Predictive Model, Justin C. Wheatcroft

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An optical material parameter predictive model that accounts for sample to air interfaces was developed. The model predicts how a terahertz time-domain spectroscopy time domain pulse will be affected as it passes through a given thickness of a material. The model assumes a homogenous, linear, isotropic dielectric or semiconductor. The inputs to the model are the real and imaginary refractive indices across the desired frequency band. Different dielectric material's optical parameters were taken from the literature and the predicted time domain pulses were shown. It was also shown that the refractive index and absorption coefficient for samples that were optically …

Electronic And Structural Properties Of Silicene And Graphene Layered Structures, Patrick B. Benasutti

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Graphene is a two-dimensional nanomaterial with useful and novel properties, but it is a material that does not integrate well with the current silicon microchip infrastructure. Silicene could solve this problem, as it is made of silicon yet retains the novel properties that make graphene desirable. This thesis will outline density functional calculations of a newly proposed structure involving the combination of these two materials. The structure includes silicene layered on graphene in such a manner that it composes a superlattice. It will be examined using the ab-initio density functional theory software Quantum Espresso.

This superlattice structure is proposed to …

Photorefractive Thin Films And Polymers For Use In Organic-Inorganic Hybrid Cells, Steven Harris Buller

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Two classes of materials were investigated as possible replacements for the bulk photorefractive windows in inorganic-organic hybrid cells: thin films and polymers. Each material was fabricated and subsequently characterized using two different methods due to their different stages of development. The thin films were characterized by X-ray diffraction while the polymers were characterized by two-beam coupling. Thin films of strontium barium niobate and potassium niobate were grown, using pulsed laser deposition, on four different substrates. It was found that it was possible to grow a thin film of potassium niobate in the correct orientation to replace a bulk photorefractive window. …

On The Quantization Problem In Curved Space, Benjamin Bernard

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The nonrelativistic quantum mechanics of particles constrained to curved surfaces is studied. There is open debate as to which of several approaches is the correct one. After a review of existing literature and the required mathematics, three approaches are studied and applied to a sphere, spheroid, and triaxial ellipsoid.

The first approach uses differential geometry to reduce the problem from a three dimensional problem to a two-dimensional problem. The second approach uses three dimensions and holds one of the separated wavefunctions and its associated coordinate constant. A third approach constrains the particle in a three-dimensional space between two parallel surfaces …

Comparing Us And Chinese High-School Physics Teaching In Terms Of The Use Of Inquiry, Lingbo Qian

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Inquiry based teaching has been widespread in the United States as well as in China in the last two decades. It was implemented by many teachers and shown to be effective in both countries. This study examines the extent to which inquiry-based teaching in high-school physics is practiced in US and China through the use of lesson observations and a survey. Nineteen lessons taught by 19 teachers (9 US and 10 Chinese) were observed (N=19). Results show that both US and Chinese teachers know well about the inquiry-based teaching. However, in practice, little inquiry-based teaching was observed in the two …

Dielectric Constant Measurements Using Atomic Force Microscopy System, Hembathanthirige Yasas Dhanapala

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A new technique to obtain local dielectric constant of thin films was developed using atomic force microscopy system. This technique, in addition to other characterization methods such as AFM imaging and X-Ray diffraction, was used to study, as an example, dielectric constant of thin films of 0.3BiScO3 - 0.7BaTiO3. The thin films were fabricated by using pulsed laser deposition technique under following temperature of the substrate: 6500C, 7000C and 7500C. At each temperature, two different oxygen pressures were used in deposition chamber: 50 mTorr and 100 mTorr. Our goal was to find optimal growth conditions with the highest dielectric constant …

Radio-Frequency Heating Of Magnetic Nanoparticles, Mohammud Zafrullah Jagoo

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In the present study, a power supply capable of converting a direct current into an alternating current was built. The frequency of oscillation of the output current could be varied from 174.8 kHz to 726.0 kHz by setting a set of capacitors in resonance. To this power supply is attached a 20-turns copper coil in the shape of a spiral. Because of the high heat generated in the coil, the latter has to be permanently water-cooled. A vacuum pump removes the air between the sample holder and the coil. A fiber optic temperature sensor with an accuracy of 0.001 K …

The Mechanisms Of Luminescence From Zno Under Electron Irradiation, Devin Marlinjames Todd

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Zinc Oxide has been utilized for centuries in a wide range of applications including medical, food, and materials. It is now that ZnO draws much attention to its potential as a high frequency semiconductor and UV laser. As a result, there has been much investigation into the properties of ZnO and many papers have been published in the area. Despite this fact, there is still much that is unknown about its electronic defect structure. This research investigates the broad region of the Zinc Oxide luminescence spectrum known as the green band, which lies roughly between 480 - 580 nm or …

Characterization Of Structured Nanomaterials Using Terahertz Frequency Radiation, Andrew John Niklas

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Measurements that use terahertz frequency radiation to characterize materials are beneficial for scientists trying to determine the physical parameters that govern the interaction of electromagnetic waves and matter at those frequencies. Results will be presented of time domain terahertz spectroscopy measurements taken in forward and backward scattering directions from vertically aligned arrays of multi-walled carbon nanotubes and thin films of perforated copper. The intent of this research is to both corroborate results from independent research groups conducting similar experiments and to further increase understanding in the scientific community with respect to carbon nanotube reflection phenomena at terahertz frequencies.