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High-Performance Self-Powered Uv Detector Based On Sno2-Tio2 Nanomace Arrays, Duo Chen, Lin Wei, Lingpan Meng, Yanxue Chen, Yufeng Tian, Shishen Yan, Liangmo Mei, Jun Jiao 2018 School of Physics and State Key Laboratory of Crystal MaterialsShandong UniversityJinanPeople’s Republic of China

High-Performance Self-Powered Uv Detector Based On Sno2-Tio2 Nanomace Arrays, Duo Chen, Lin Wei, Lingpan Meng, Yanxue Chen, Yufeng Tian, Shishen Yan, Liangmo Mei, Jun Jiao

Physics Faculty Publications and Presentations

Photoelectrochemical cell-typed self-powered UV detectors have attracted intensive research interest due to their low cost, simple fabrication process, and fast response. In this paper, SnO2-TiO2 nanomace arrays composed of SnO2 nanotube trunk and TiO2 nanobranches were prepared using soft chemical methods, and an environment-friendly self-powered UV photodetector using this nanostructure as the photoanode was assembled. Due to the synergistic effect of greatly accelerated electron-hole separation, enhanced surface area, and reduced charge recombination provided by SnO2-TiO2 nanomace array, the nanostructured detector displays an excellent performance over that based on bare SnO2 arrays. The impact of the growing time of TiO2 branches ...


Radical Social Ecology As Deep Pragmatism: A Call To The Abolition Of Systemic Dissonance And The Minimization Of Entropic Chaos, Arielle Brender 2018 Fordham University

Radical Social Ecology As Deep Pragmatism: A Call To The Abolition Of Systemic Dissonance And The Minimization Of Entropic Chaos, Arielle Brender

Student Theses 2015-Present

This paper aims to shed light on the dissonance caused by the superimposition of Dominant Human Systems on Natural Systems. I highlight the synthetic nature of Dominant Human Systems as egoic and linguistic phenomenon manufactured by a mere portion of the human population, which renders them inherently oppressive unto peoples and landscapes whose wisdom were barred from the design process. In pursuing a radical pragmatic approach to mending the simultaneous oppression and destruction of the human being and the earth, I highlight the necessity of minimizing entropic chaos caused by excess energy expenditure, an essential feature of systems that aim ...


Experimental Progress Toward Eit In An Atomic Beam, Sean E. Tilton 2018 Lake Forest College

Experimental Progress Toward Eit In An Atomic Beam, Sean E. Tilton

Senior Theses

EIT (Electromagnetically Induced Transparency) is a quantum optics phenomenon that occurs under specific conditions during a photon-atom interaction. Under such conditions, slow-light may be produced as a by-product of this effect. The purpose of this research is to adapt previous work on rubidium atoms in vapor cells to lithium atoms in a thermal beam. By doing so, the hope is to better understand the limitations of slow light and produce better results by eliminating atomic collisions within the system.


A Sixteen-Channel Nanoammeter Current Measurement System For Profiling Charged Particle Beams, Zachery St. Pierre 2018 College of the Holy Cross

A Sixteen-Channel Nanoammeter Current Measurement System For Profiling Charged Particle Beams, Zachery St. Pierre

Physics Student Scholarship

No abstract provided.


Physics 516: Electromagnetic Phenomena (Spring 2018), Philip C. Nelson 2018 University of Pennsylvania

Physics 516: Electromagnetic Phenomena (Spring 2018), Philip C. Nelson

Department of Physics Papers

These course notes are made publicly available in the hope that they will be useful. All reports of errata will be gratefully received. I will also be glad to hear from anyone who reads them, whether or not you find errors: pcn@upenn.edu.


Spatially-Resolved Study Of The Meissner Effect In Superconductors Using Nv-Centers-In-Diamond Optical Magnetometry, Naufer Nusran, Kamal R. Joshi, Kyuil Cho, Makariy A. Tanatar, William R. Meier, Sergey Bud’ko, Paul C. Canfield, Yong Liu, Thomas A. Lograsso, Ruslan Prozorov 2018 Iowa State University and Ames Laboratory

Spatially-Resolved Study Of The Meissner Effect In Superconductors Using Nv-Centers-In-Diamond Optical Magnetometry, Naufer Nusran, Kamal R. Joshi, Kyuil Cho, Makariy A. Tanatar, William R. Meier, Sergey Bud’Ko, Paul C. Canfield, Yong Liu, Thomas A. Lograsso, Ruslan Prozorov

Ames Laboratory Accepted Manuscripts

Non-invasive magnetic field sensing using optically-detected magnetic resonance of nitrogen-vacancy centers in diamond was used to study spatial distribution of the magnetic induction upon penetration and expulsion of weak magnetic fields in several representative superconductors. Vector magnetic fields were measured on the surface of conventional, elemental Pb and Nb, and compound LuNi2B2C and unconventional iron-based superconductors Ba1−x KxFe2As2 (x=0.34 optimal hole doping), Ba(Fe1−x Cox)2As2 (x=0.07 optimal electron doping), and stoichiometric CaKFe4As4, using variable-temperature confocal system with diffraction-limited spatial resolution. Magnetic induction profiles across the crystal edges were measured in zero-field-cooled and field-cooled ...


Quasiprobability Behind The Out-Of-Time-Ordered Correlator, Nicole Yunger Halpern, Brian Swingle, Justin Dressel 2018 California Institute of Technology

Quasiprobability Behind The Out-Of-Time-Ordered Correlator, Nicole Yunger Halpern, Brian Swingle, Justin Dressel

Mathematics, Physics, and Computer Science Faculty Articles and Research

Two topics, evolving rapidly in separate fields, were combined recently: the out-of-time-ordered correlator (OTOC) signals quantum-information scrambling in many-body systems. The Kirkwood-Dirac (KD) quasiprobability represents operators in quantum optics. The OTOC was shown to equal a moment of a summed quasiprobability [Yunger Halpern, Phys. Rev. A 95, 012120 (2017)]. That quasiprobability, we argue, is an extension of the KD distribution. We explore the quasiprobability's structure from experimental, numerical, and theoretical perspectives. First, we simplify and analyze Yunger Halpern's weak-measurement and interference protocols for measuring the OTOC and its quasiprobability. We decrease, exponentially in system size, the number of ...


Characterization Of Magnetic Thin Films Using The Magneto Optic Kerr Effect, Nicholas J. Savino 2018 Lynchburg College

Characterization Of Magnetic Thin Films Using The Magneto Optic Kerr Effect, Nicholas J. Savino

Student Scholar Showcase

Understanding magnetic properties of materials allows for advances in applications such as data storage. The Magneto-Optic Kerr Effect (MOKE) displays the reflective response a magnetic material has to a magnetic field. When polarized light reflects off of a magnetic material, the polarization orientation can change. The application of an external magnetic field can affect how much this polarization changes in a non-linear manner. Hysteresis loops are created when examining the relationship between intensity of the reflected light to the applied magnetic field provide information about magnetic properties of that material, such as the coercive field and field retention. Preliminary measurements ...


Effect Of Fe Substitution On Structural, Magnetic And Electron-Transport Properties Of Half-Metallic Co2tisi, Juliana Herran 2018 University of Northern Iowa

Effect Of Fe Substitution On Structural, Magnetic And Electron-Transport Properties Of Half-Metallic Co2tisi, Juliana Herran

Research in the Capitol

In recent years, research on magnetic materials has been one of the most technologically appealing developments in materials science. Among other applications, magnetic materials are essential components of data storage and information processing in computer hardware elements, such as hard drives and random access memories. Here, we present a theoretical study of structural, magnetic and electronic properties of ferrimagnetic Co2Ti1−xFexSi (x = 0, 0.25, 0.5), using density functional calculations. We show that the magnetic moment of Co2Ti1−xFexSi increases when Ti is substituted with Fe, consistent ...


Dissipation Effects In Schrödinger And Quantal Density Functional Theories Of Electrons In An Electromagnetic Field, Xiao-Yin Pan, Viraht Sahni 2018 Ningbo University

Dissipation Effects In Schrödinger And Quantal Density Functional Theories Of Electrons In An Electromagnetic Field, Xiao-Yin Pan, Viraht Sahni

Publications and Research

Dissipative effects arise in an electronic system when it interacts with a time-dependent environment. Here, the Schrödinger theory of electrons in an electromagnetic field including dissipative effects is described from a new perspective. Dissipation is accounted for via the effective Hamiltonian approach in which the electron mass is time-dependent. The perspective is that of the individual electron: the corresponding equation of motion for the electron or time-dependent differential virial theorem—the ‘Quantal Newtonian’ second law—is derived. According to the law, each electron experiences an external field comprised of a binding electric field, the Lorentz field, and the electromagnetic field ...


Time-Resolved Electron (E,2E) Momentum Spectroscopy: Application To Laser-Driven Electron Population Transfer In Atoms, Hua-Chieh Shao, Anthony F. Starace 2018 University of Nebraska - Lincoln

Time-Resolved Electron (E,2E) Momentum Spectroscopy: Application To Laser-Driven Electron Population Transfer In Atoms, Hua-Chieh Shao, Anthony F. Starace

Anthony F. Starace Publications

Owing to its ability to provide unique information on electron dynamics, time-resolved electron momentum spectroscopy (EMS) is used to study theoretically a laser-driven electronic motion in atoms. Specifically, a chirped laser pulse is used to adiabatically transfer the populations of lithium atoms from the ground state to the first excited state. During this process, impact ionization near the Bethe ridge by time-delayed ultrashort, high-energy electron pulses is used to image the instantaneous momentum density of this electronic population transfer. Simulations with 100 fs and 1 fs pulse durations demonstrate the capability of EMS to image the time-varying momentum density, including ...


Simulation Of Charge Transport In Multi-Island Tunneling Devices: Application To Disordered One-Dimensional Systems At Low And High Biases, Madhusudan A. Savaikar, Douglas R. Banyai, Paul Bergstrom, John A. Jaszczak 2018 Michigan Technological University

Simulation Of Charge Transport In Multi-Island Tunneling Devices: Application To Disordered One-Dimensional Systems At Low And High Biases, Madhusudan A. Savaikar, Douglas R. Banyai, Paul Bergstrom, John A. Jaszczak

John Jaszczak

Although devices have been fabricated displaying interesting single-electron transport characteristics, there has been limited progress in the development of tools that can simulate such devices based on their physical geometry over a range of bias conditions up to a few volts per junction. In this work, we present the development of a multi-island transport simulator, MITS, a simulator of tunneling transport in multi-island devices that takes into account geometrical and material parameters, and can span low and high source-drain biases. First, the capabilities of MITS are demonstrated by modeling experimentaldevices described in the literature, and showing that the simulated device ...


Roughening And Preroughening Of Diamond-Cubic {111} Surfaces, Donald L. Woodraska, John A. Jaszczak 2018 Michigan Technological University

Roughening And Preroughening Of Diamond-Cubic {111} Surfaces, Donald L. Woodraska, John A. Jaszczak

John Jaszczak

A solid-on-solid model for {111} surfaces of diamond-cubic materials that correctly takes into account the diamond-cubic crystal structure has been developed for Monte Carlo simulation. In addition to a roughening transition at temperature TR, a distinct preroughening transition at TPR≈0.43TR is indicated by divergences in the surface specific heat and order-parameter susceptibility. Preroughening appears to arise naturally in our nearest-neighbor bond model from the entropic freedom available in the nontrivial crystal structure. Preroughening is shown to dramatically lower the nucleation barrier for growth and etching at low driving forces.


Mechanism For Spatial Organization In Quantum Dot Self-Assembly, Da Gao, Adam Kaczynski, John A. Jaszczak 2018 Michigan Technological University

Mechanism For Spatial Organization In Quantum Dot Self-Assembly, Da Gao, Adam Kaczynski, John A. Jaszczak

John Jaszczak

Inspired by experimental observations of spatially ordered growth hillocks on the (001) surfaces of natural graphite crystals, a mechanism for spatial organization in quantum dotself-assembly is proposed. The regular arrangement of steps from a screw dislocation-generated growth spiral provides the overall template for such ordering. An ordered array of quantum dots may be formed or nucleated from impurities driven to the step corners by diffusion and by their interactions with the spiral’s steps and kinks. Kinetic Monte Carlo simulation of a solid-on-solid model supports the feasibility of such a mechanism.


Understanding The Nature Of Nanoscale Wetting Through All-Atom Simulations, Oliver Evans 2018 The University of Akron

Understanding The Nature Of Nanoscale Wetting Through All-Atom Simulations, Oliver Evans

Honors Research Projects

The spreading behavior of spherical and cylindrical water droplets between 30Å and 100Å in radius on a sapphire surface is investigated using all-atom molecular dynamics simulations for durations on the order of tens of nanoseconds. A monolayer film develops rapidly and wets the surface, while the bulk of the droplet spreads on top of the monolayer, maintaining the shape of a spherical cap. Unlike previous simulations in the literature, the bulk radius is found to increase to a maximum value and receed as the monolayer continues to expand. Simple time and droplet size dependence is observed for monolayer radius and ...


Creating A Better Source Of 118 Nm Light, Benjamin Saarel 2018 University of Colorado, Boulder

Creating A Better Source Of 118 Nm Light, Benjamin Saarel

Undergraduate Honors Theses

The observed molecule signal in cold molecule experiments is limited by the molecule source and the efficiency of the detection method. The purpose of my thesis work was to improve the scientific apparatus physicists use to trap and detect cold molecules. The first part of my thesis focuses on improving a new cold molecule source known as a Nijmegen Pulsed Valve by optimizing the parameters used to run it. The valve worked best when operating at a voltage of 8-12V, valve pulse duration of 70-100 microseconds, and valve frequency of 1Hz. The new Neijmegen Pulsed Valve, run with optimized parameters ...


Block-Copolymer Assisted Fabrication Of Anisotropic Plasmonic Nanostructures, Calbi J. Gunder 2018 Missouri State University

Block-Copolymer Assisted Fabrication Of Anisotropic Plasmonic Nanostructures, Calbi J. Gunder

MSU Graduate Theses

The anisotropic nanostructures of noble metals are of great interest for plasmonic applications due to the possibility of tuning the localized surface plasmon resonance (LSPR) across the UV-VIS-NIR without sacrificing the linewidth as well as to achieve larger local field enhancement. Here, we report a simple and promising fabrication method of anisotropic gold nanostructures film using polystyrene-b-2vinylpyridine (PS-b-P2VP) block copolymers (BCP) as a template. In this approach, PS-b-P2VP spherical micelles were first synthesized as a template followed by selective deposition of Au precursor inside P2VP core of the micelles using ethanol solution of Au salt. Subsequently, heat treatment of the ...


Photoelectron Angular Distributions From Rotationally Resolved Autoionizing States Of N2, Alexander M. Chartrand, Elizabeth F. McCormack, Ugo Jacovella, David M P Holland, Berenger Gans, Xiaofeng Tang, Gustavo A. García, Laurent Nahon, Stephen T. Pratt 2017 Bryn Mawr College

Photoelectron Angular Distributions From Rotationally Resolved Autoionizing States Of N2, Alexander M. Chartrand, Elizabeth F. Mccormack, Ugo Jacovella, David M P Holland, Berenger Gans, Xiaofeng Tang, Gustavo A. García, Laurent Nahon, Stephen T. Pratt

Physics Faculty Research and Scholarship

The single-photon, photoelectron-photoion coincidence spectrum of N2 has been recorded at high (~1.5 cm–1 ) resolution in the region between the N2+ X 2Σg+, v+ = 0 and 1 ionization thresholds by using a double-imaging spectrometer and intense vacuum-ultraviolet light from the Synchrotron SOLEIL. This approach provides the relative photoionization cross section, the photoelectron energy distribution, and the photoelectron angular distribution as a function of photon energy. The region of interest contains autoionizing valence states, vibrationally autoionizing Rydberg states converging to vibrationally excited levels of the N2+ X 2Σg+ ground state, and electronically ...


Angle-Resolved Observation Of X-Ray Second Harmonic Generation In Diamond, Björn Senfftleben 2017 University of Nebraska-Lincoln

Angle-Resolved Observation Of X-Ray Second Harmonic Generation In Diamond, Björn Senfftleben

Theses, Dissertations, and Student Research: Department of Physics and Astronomy

This thesis reports angularly-resolved observation of X-ray second harmonic generation (XSHG) in diamond at several phase-matching geometries. The XSHG signal was produced by ultra-short, highly intense X-ray pulses with a photon energy of 9.831 keV generated by a free-electron laser. In some geometries for high pulse energies more than 10 second harmonic photons per pulse were generated.

Different phase-matched geometries were used for XSHG to investigate the angular dependence of the efficiency of the process. Furthermore, for each phase-matching condition, the quadratic dependence for second harmonic generation at each geometry was verified and the crystal rocking curves were measured ...


Design And Construction Of A High-Current Femtosecond Gas-Phase Electron Diffraction Setup, Omid Zandi 2017 University of Nebraska-Lincoln

Design And Construction Of A High-Current Femtosecond Gas-Phase Electron Diffraction Setup, Omid Zandi

Theses, Dissertations, and Student Research: Department of Physics and Astronomy

We designed and constructed a state-of-the-art high current ultrafast gas electron diffraction experimental setup, which resolved two main challenges that constraint temporal resolution in previous setups. These aforementioned bottlenecks were: the space charge effect due to the Coulomb expansion, and the velocity mismatch between the sub-relativistic electrons (probe) and the exciting laser pulse (pump). In our setup, the problem of space charge effect was ameliorated by compressing 90 keV photo-emitted electron pulses using a radio-frequency electric field. The compression allowed us to increase the beam current by almost two orders of magnitude higher than previously reported. We developed a laser-activated ...


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