Other Physics Commons^™

Experimental And Numerical Analysis Of Coupling Between Musical Drumheads, Ben Boe

Summer Research

The low frequency vibrations of two-headed musical drums are known to couple. However, little is known regarding the factors that determine the degree of coupling at higher frequencies. In this study the effects that depth, diameter and head tension have on the tendency of the drumheads to couple are investigated. Commercial finite element software was used to model a wide range of drums and to identify trends of coupling according to these factors. The numerical results were used to guide which parameters should be tested in the lab. Experimentally, two oppositely facing Electronic Speckle-Pattern Interferometry systems were used to optically …

Adsorption Of Tcnqh-Functionalized Quinonoid Zwitterions On Gold And Graphene: Evidence For Dominant Intermolecular Interactions+, Lingmei Kong, Lucie Routaboul, Pierre Braunstein, Hong-Gi Park, Jaewu Choi, John P. Colon Cordova, E Vega, Luis G. Rosa, Bernard Doudin, Peter A. Dowben

Peter Dowben Publications

We experimentally investigate the electronic structure of the strongly dipolar, quinonoid-type molecule obtained by TCNQH-functionalization (TCNQH = (NC)₂CC₆H₄CH(CN)₂) of (6Z)-4-(butylamino)-6-(butyliminio)- 3-oxocyclohexa-1,4-dien-1-olate C₆H₂(...NHR)₂(...O)₂ (where R = n-C₄H₉) to be very similar after deposition from solution on either graphene or gold substrates. These zwitterion adsorbate thin films form structures that are distinct from those formed by related quinonoid molecules previously studied. We argue that adsorbate–adsorbate interactions dominate and lead to a Stranski–Krastanov ‘island growth’ mechanism.

Search For Spin-Polarized Photoemission From Gaas Using Light With Orbital Angular Momentum, Nathan B. Clayburn, J. L. Mccarter, J. M. Dreiling, M. Poelker, D. M. Ryan, Timothy J. Gay

Timothy J. Gay Publications

Laser light with photon energy near the band gap of GaAs and in Laguerre-Gaussian modes with different amounts of orbital angular momentum was used to produce photoemission from unstrained GaAs. The degree of electron spin polarization was measured using a micro-Mott polarimeter and found to be consistent with zero with an upper limit of ∼3% for light with up to ±5h of orbital angular momentum. In contrast, the degree of spin polarization of 32.3 ± 1.4% using circularly polarized laser light at the as the same wavelength, which is typical for bulk GaAs photocathodes.

Threshold Alignment Reversal And Circularly Polarized Fluorescence In Rotationally Resolved H2, Jack W. Maseberg, Klaus Bartschat, Timothy J. Gay

Timothy J. Gay Publications

Using H₂ and D₂ targets, we have measured the polarization of Fulcher-band fluorescence resulting from spin-polarized electron-impact excitation of vibrationally and rotationally resolved d ³Π_u→ a ³ ∑_g⁺ transitions for incident electron energies from 14.3 to 28.5 eV. Near threshold, the linear polarization P₁ descends from positive values through zero to negative values, indicating a dynamic production of M_N = 0 states. The circular polarization P₃ is measured to be nonzero, indicating the orientation of rotationally resolved molecular states. For Q-branch transitions, P₃ is consistent with theory based …

Compact Inline Optical Electron Polarimeter, Munir Pirbhai, D. M. Ryan, G. Richards, Timothy J. Gay

Timothy J. Gay Publications

A compact optical electron polarimeter using a helium target is described. It offers a maximum fluorescence detection efficiency of ∼20 Hz/nA, which is an order of magnitude higher than that of earlier designs. With an argon target, this device is expected to have a polarimetric figure-of-merit of 270 Hz/nA. By relying on a magnetic field to guide a longitudinally spin-polarized electron beam, the present instrument employs fewer electrodes. It also uses a commercially available integrated photon counting module. These features allow it to occupy a smaller volume and make it easier to operate.

Two Novel Approaches For Electron Beam Polarization From Unstrained Gaas, James L. Mccarter, Nathan B. Clayburn, J. M. Dreiling, Timothy J. Gay, Dominic M. Ryan, John Hansknecht, Matt Poelker, Andrei Afanasev, Ara Kechiantz

Timothy J. Gay Publications

Two novel approaches to producing highly-polarized electron beams from unstrained GaAs were tested using a micro-Mott polarimeter. Based on a suggestion by Nakanishi [1]], twophoton photoemission with 1560 nm light was used with photocathodes of varying thickness: 625m, 0.32m, and 0.18m. For each of these photocathodes, the degree of spin polarization of the photoemitted beam was less than 50%. Polarization via two-photon absorption was highest from the thinnest photocathode sample and close to that obtained from one-photon absorption (using 778 nm light), with values 40.3±1.0% and 42.6±1.0%, respectively. The second attempt to produce highly-polarized electrons used one-photon emission with 778 …

Changing Molecular Band Offsets In Polymer Blends Of (P3ht/P(Vdf–Trfe)) Poly(3-Hexylthiophene) And Poly(Vinylidene Fluoride With Trifluoroethylene) Due To Ferroelectric Poling, Freddy Wong, Godohaldo Perez, Manuel Bonilla, Juan A. Colon-Santana, Xin Zhang, Pankaj Sharma, Alexei Gruverman, Peter A. Dowben, Luis G. Rosa

Peter Dowben Publications

Photoelectron emission and inverse photoemission spectroscopy studies of polymer blends of poly(vinylidene fluoride (70%) – trifluoroethylene (30%)) P(VDF–TrFE 70 : 30) and regio-regular poly(3- hexylthiophene) (P3HT) provide evidence of changes in the molecular band offsets as a result of changes in the ferroelectric polarization in P(VDF–TrFE). Investigation of the blends with higher concentrations of the semiconducting P3HT component revealed that the organic semiconductor component of the blend dominates the electronic structure in the vicinity of the chemical potential. Specifically, the states of P3HT at the conduction band minimum and valence band maximum fall within the HOMO–LUMO gap of the dielectric …

Induced Magneto-Electric Coupling In Ferroelectric/Ferromagnetic Heterostructures, Jeffery Carvell, Ruihua Cheng, Peter A. Dowben, Q Yang

Peter Dowben Publications

Using an external magnetic field, we have demonstrated room temperature control of the electric polarization of a ferroelectric polymer, polyvinylidene fluoride (PVDF), in an artificial multiferroic structure. For ferroelectric PVDF polymer thin films in an iron-PVDF-iron heterostructure, both the ferroelectric coercivity and polarization display a hysteresis dependence on the external magnetic field. We also find that the thickness of the PVDF layer has an effect on the magnetoelectric coupling in our samples. We observe a giant magnetoelectric coupling with values as large as 3700 V/cm Oe to 41700 V/cm Oe.

Magnetoelectric Coupling At The Euo/Batio3 Interface, Shi Cao, P Liu, Jinke Tang, Haidong Lu, C W. Bark, Sangjin Ryu, Chang-Beom Eom, Alexei Gruverman, Peter A. Dowben

Peter Dowben Publications

Magnetization modulation by ferroelectric polarization switching is reported for the ferromagnetic-ferroelectric EuO/BaTiO₃heterostructure. The value of the magnetization critical exponent β is consistent with the expected Heisenberg-like ferromagnetism of EuO and reported Curie temperature. The critical exponent is seen to decrease with increased magnetic coupling. The results are discussed in the context of data obtained earlier for epitaxial La_0.67Sr_0.33MnO₃/BaTiO₃ heterostructures, where magnetization increases and critical exponent b also declines with ferroelectric polarization pointing away from ferromagnetic layer. The observed similarity between two systems illustrates an importance of charge doping in magnetoelectric coupling, …

Review Of Computing With Quantum Cats: From Colossus To Qubits And Schrödinger’S Killer App: Race To Build The World’S First Quantum Computer, Matthew S. Leifer

Mathematics, Physics, and Computer Science Faculty Articles and Research

Book reviews of Computing With Quantum Cats: From Colossus To Qubits by John Gribbin and Schrödinger’s Killer App: Race To Build The World’s First Quantum Computer by John Dowling.

Oblique-Length Contraction Factor In The Special Theory Of Relativity, Florentin Smarandache

Branch Mathematics and Statistics Faculty and Staff Publications

In this paper one generalizes the Lorentz Contraction Factor for the case when the lengths are moving at an oblique angle with respect to the motion direction. One shows that the angles of the moving relativistic objects are distorted.

Point–Counterpoint: Can Anything Be Learned From Surveys On The Interpretations Of Quantum Mechanics?, Matthew S. Leifer, Nathan Harshman

Mathematics, Physics, and Computer Science Faculty Articles and Research

"In what follows, Matt Leifer and Nathan Harshman present opposing views on the value of surveys on foundational attitudes towards quantum mechanics. Three such surveys were recently published and their results are summarized in Table 1. Matt takes the `point,’ arguing that such surveys are not useful, while Nathan takes the `counterpoint.’ A complete set of references for both is given at the end."

Excitation Of Radiative Polaritons By Polarized Broadband Infrared Radiation In Thin Oxide Films Deposited By Atomic Layer Deposition, Anita J. Vincent-Johnson, Andrew E. Masters, Xiaofeng Hu, Giovanna Scarel

Department of Physics and Astronomy - Faculty Scholarship

This work contributes to the understanding of infrared radiation interaction with matter and its absorption for energy harvesting purposes. By exciting radiative polaritons in thin oxide filmswith polarized infrared radiation, a further evidence is collected that a link exists between radiative polaritons and the heat recovery mechanism hypothesized in previous research. In the voltage transient occurring when the infrared radiation is turned on, the observed time necessary to reach the maximum voltage and the voltage intensity versus angle of incidence exhibit a mismatch when generated by polarized and nonpolarized infrared radiation. The existence of collective charge oscillation modes in the …

Synthesis Of Al2tio5 And Its Effect On The Properties Of Chitosan-Nh4scn Polymer Electrolytes, Siti Rohana Majid, Hassan F., Woo H. J., Aziz N. A., Kufian M. Z.

Siti Rohana Majid

In this paper, Al2TiO5 ceramic material has been synthesised and used as filler in polymer electrolyte system to enhance the conductivity. The precursor sintered at 1,050 A degrees C and contained 0.08 mole of aluminium nitrate gives the best and complete formation of Al2TiO5. Composite polymer electrolytes of chitosan-NH4SCN containing different amount of home-made Al2TiO5 were prepared by solution casting. The addition of filler has enhanced the conductivity of polymer electrolyte. The sample 57 wt% chitosan-38 wt% NH4SCN-5 wt% Al2TiO5 exhibited the highest electrical conductivity of 2.10 x 10(-4) S cm(-1) at room temperature. The presence of the Al2TiO5 creates …

The Effect Of Antimony Trioxide On Poly (Vinyl Alcohol)-Lithium Perchlorate Based Polymer Electrolytes, Siti Rohana Majid, Lim C. S., Ramesh S.

Siti Rohana Majid

A new type of inorganic filler antimony trioxide (Sb2O3) is used to prepare composite polymer electrolytes based on poly (vinyl alcohol) (PVA) and lithium perchlorate (LiClO4) by solution casting technique. The incorporation of Sb2O3 enhances the ionic conductivity at ambient temperature and exhibits the highest ionic conductivity value of 9.51 x 10(-5) S cm(-1) upon the addition of 6 wt% Sb2O3. Thermogravimetric analyses (TGA) reveal that the second weight loss is reduced. This shows the improvement in thermal stability of electrolyte film upon addition of Sb2O3. Differential scanning calorimetry (DSC) analyses show that the glass transition temperature (T-g) value decreases …

Determination Of Kinetic Parameters From The Thermogravimetric Data Set Of Biomass Samples, Karol Postawa, Wojciech M. Budzianowski

Wojciech Budzianowski

This article describes methods of the determination of kinetic parameters from the thermogravimetric data set of biomass samples. It presents the methodology of the research, description of the needed equipment, and the method of analysis of thermogravimetric data. It describes both methodology of obtaining quantitative data such as kinetic parameters as well as of obtaining qualitative data like the composition of biomass. The study is focused mainly on plant biomass because it is easy in harvesting and preparation. Methodology is shown on the sample containing corn stover which is subsequently pyrolysed. The investigated sample show the kinetic of first order …

Simultaneous Radar And Video Meteors, Robert J. Weryk

Electronic Thesis and Dissertation Repository

The goal of this thesis is to better understand the physical and chemical properties of meteoroids by using simultaneous radar and video observations of meteors. The Canadian Meteor Orbit Radar (CMOR) and several Gen-III image-intensified CCD cameras were used to measure common meteors and validate metric errors determined through Monte Carlo modelling and to relate radar electron line density (q) to video photon radiant power (I). By adopting an ionisation coefficient from Jones (1997) and using recorded measurements of q/I, a corresponding estimate of the fraction of meteoroid kinetic energy loss converted into light (luminous efficiency) was found.

It was …

Aspects Of General Relativity In 1+1 Dimensions, Richard D. Mellinger Jr

Physics

What would be the properties of a universe with only one spatial dimension and one time dimension? General relativity in 1+1 dimensions is unique since the two curvature terms in the Einstein field equations cancel. This makes the Einstein field equations algebraic rather than differential equations. This special feature can make 1+1 dimensionality attractive as an instructional tool to simplify the mathematics that many beginners find opaque. We explore the implications and features of the Einstein field equations in 1+1 dimensions and find they provide a surprisingly rich and interesting model. We then study an alternate theory and its implications …

Development Of A Novel Technique For Predicting Tumor Response In Adaptive Radiation Therapy, Rebecca Marie Seibert

Doctoral Dissertations

This dissertation concentrates on the introduction of Predictive Adaptive Radiation Therapy (PART) as a potential method to improve cancer treatment. PART is a novel technique that utilizes volumetric image-guided radiation therapy treatment (IGRT) data to actively predict the tumor response to therapy and estimate clinical outcomes during the course of treatment. To implement PART, a patient database containing IGRT image data for 40 lesions obtained from patients who were imaged and treated with helical tomotherapy was constructed. The data was then modeled using locally weighted regression. This model predicts future tumor volumes and masses and the associated confidence intervals based …

Logistic Curves, Extraction Costs And Peak Oil, Robert J. Brecha

Physics Faculty Publications

Debates about the possibility of a near-term maximum in world oil production have become increasingly prominent over the past decade, with the focus often being on the quantification of geologically available and technologically recoverable amounts of oil in the ground. Economically, the important parameter is not a physical limit to resources in the ground, but whether market price signals and costs of extraction will indicate the efficiency of extracting conventional or nonconventional resources as opposed to making substitutions over time for other fuels and technologies. We present a hybrid approach to the peak-oil question with two models in which the …