Spectroscopic End Point Detection With An Electron Beam Evaporator, 2024 Portland State University
Spectroscopic End Point Detection With An Electron Beam Evaporator, Ryan M. Mcgraw
University Honors Theses
Spectroscopic end point detection is a com- mon tool used for measuring slope changes in
wavelength intensity. Using algorithms able to apply this concept, coatings will be able to be dynamically measured in real time and stopped
at the appropriate level to ensure process uni- formity. It is currently applied to reductive pro- cesses such as etching, where the surface will
start to be eaten away, creating a plasma. When the entire amount of a material on a substrate has been eaten away, the plasma will change
color as it is beginning to etch a different ma- terial. Using a …
On The Exact Helium Wave Function Expansion, Ii, An Exponential Modulated Form, 2024 University of Connecticut
On The Exact Helium Wave Function Expansion, Ii, An Exponential Modulated Form, Carl W. David
Chemistry Education Materials
A 11S wave function’s expansion for 2 electron atoms and ions is proposed employing an appropriate exponential factor and Fock’s logarithmic terms. The leading coefficient’s are presented.
Light That Appears To Come From A Source That Does Not Exist, 2024 The Hebrew University of Jerusalem
Light That Appears To Come From A Source That Does Not Exist, Itamar Stern, Yakov Bloch, Einav Grynszpan, Merav Kahn, Yakir Aharonov, Justin Dressel, Eliahu Cohen, John C. Howell
Mathematics, Physics, and Computer Science Faculty Articles and Research
Superoscillatory, band-limited functions oscillate faster than their fastest Fourier component. Superoscillations have been intensively explored recently as they give rise to many out-of-the-spectrum phenomena entailing both fundamental and applied significance. We experimentally demonstrate a form of superoscillations which is manifested by light apparently coming from a source located far away from the actual one. These superoscillations are sensed through sharp transverse shifts in the local wave vector at the minima of a pinhole diffraction pattern. We call this phenomenon “optical ventriloquism.”
Questioning Reality: The Progressive Development Of Modern Physics, 2024 Golda Och Academy
Questioning Reality: The Progressive Development Of Modern Physics, Joshua Lancman
STEM for Success Showcase
Humanity has a tendency to divide time. The past is distinct from the present which is entirely separate from the future. In supposedly 20-20 vision history is neatly divided into different sections, distinct eras with sharp lines between them. What is present and in the future is always modern. What is past is something else with another name.
Yet time is not divided so neatly. We know this living through it: years and decades blend into one another in a non-uniform progression. To divide human history into separate eras is a necessary simplification, as it helps to ascribe order onto …
Single-Stage Few-Cycle Pulse Amplification, 2024 Manipal Institute of Technology, Manipal University
Single-Stage Few-Cycle Pulse Amplification, Sagnik Ghosh, Nathan G. Drouillard, Tj Hammond
Physics Publications
Kerr instability can be exploited to amplify visible, near-infrared, and midinfrared ultrashort pulses. We use the results of Kerr instability amplification theory to inform our simulations amplifying few-cycle pulses. We show that the amplification angle dependence is simplified to the phase-matching condition of four-wave mixing when the intense pump is considered. Seeding with few-cycle pulses near the pump leads to broadband amplification without spatial chirp, while longer pulses undergo compression through amplification. Pumping in the midinfrared leads to multioctave spanning amplified pulses with single-cycle duration not previously predicted. We discuss limitations of the amplification process and optimizing pump and seed …
Lithium Tetraborate As A Neutron Scintillation Detector: A Review, 2023 Oklahoma State University
Lithium Tetraborate As A Neutron Scintillation Detector: A Review, Elena Echeverria, John W. Mcclory, Lauren Samson, Katherine Shene, Juan A. Colon Santana, Yaroslav V. Burak, Volodymyr T. Adamiv, Ihor M. Teslyuk, Lu Wang, Wai-Ning Mei, Kyle A. Nelson, Douglas S. Mcgregor, Peter A. Dowben, Carolina C. Ilie, James C. Petrosky, Archit Dhingra
Faculty Publications
The electronic structure and translucent nature of lithium tetraborate (Li2B4O7) render it promising as a scintillator medium for neutron detection applications. The inherently large neutron capture cross-section due to 10B and 6Li isotopes and the ease with which Li2B4O7 can be enriched with these isotopes, combined with the facile inclusion of rare earth dopants (occupying the Li+ sites), are expected to improve the luminescent properties, as well as the neutron detection efficiency, of Li2B4O7. The electronic structure of both doped …
Electro-Optical Effect Of 4-N-Alkyl-Sulfanyl-4' Isothiocyanate-Biphenyl Liquid Crystal Homologous Series Under Terahertz Frequency: A Theoretical Approach, 2023 Department of Physics, School of Applied & Life Sciences, Uttaranchal University, Uttarakhand 248007, India
Electro-Optical Effect Of 4-N-Alkyl-Sulfanyl-4' Isothiocyanate-Biphenyl Liquid Crystal Homologous Series Under Terahertz Frequency: A Theoretical Approach, Yogesh Kumar, Narinder Kumar
Makara Journal of Science
This work presented the electro-optical effect of the homologous series 4-n-alkyl-sulfanyl-4'-isothiocyanate-biphenyl (N1SC13H8-SH2n+1Cn) under an electric field with terahertz (THz) frequency. The increase in alkyl sulfanyl chain length reduces the birefringence but increases the order parameter in THz frequency. An inverse relationship exists between the birefringence and order parameter. Meanwhile, the increase in alkyl sulfanyl chain length increases the refractive index with an even–odd effect. Birefringence, refractive index, order parameter, and director angle show an even–odd effect in the THz frequency range. The calculation is performed between 1 and 1,200 THz frequency. The isothiocyanate stretching corresponding to …
Analyzing The Effects Of Ultrafast Laser Processing On Mechanical Properties Of 3d-Printed Pla Parts, 2023 Florida Institute of Technology
Analyzing The Effects Of Ultrafast Laser Processing On Mechanical Properties Of 3d-Printed Pla Parts, Darshan Pramodbhai Yadav
Theses and Dissertations
Recent advances in additive manufacturing technologies have already led to wide-scale adoption of 3D-printed parts in various industries. The expansion in choice of materials that can be processed, particularly using Fused Deposition Modeling (FDM), and the steady advancements in dimensional accuracy control have extended the range of applications far beyond rapid prototyping. However, additive manufacturing still has considerable limitations compared to traditional and subtractive manufacturing processes. This work addresses limitations associated with the as-deposited surface roughness of 3D-printed parts. The effects of roughness-induced stress concentrations were studied on ultimate tensile strength and fatigue life. The samples were manufactured using a …
Radiation Exposure Calibration Of The Al2o3:C With Radium-226 And Cesium-137 Using The Osl Method, 2023 Clemson University
Radiation Exposure Calibration Of The Al2o3:C With Radium-226 And Cesium-137 Using The Osl Method, Selma Tepeli Aydin
All Theses
Optically stimulated luminescence (OSL) dosimetry was utilized to calibrate Al2O3:C powder dosimeters, available commercially as the nanoDot® from Landauer Inc., and compare the dosimeter response to radium-226 (226Ra) and cesium-137 (137Cs). The signal from the OSL was quantified using a microSTARii® OSL reader also produced by Landauer Inc. Dose-response curves were developed for 226Ra and 137Cs experiments (5 dosimeters each) at thirteen absorbed doses. Individual dosimeter response was tracked by serial number. Linear regression analysis was performed to determine if there were significant differences between the intercepts of the …
Acoustically Levitated Whispering-Gallery Mode Microlasers, 2023 Universidad de Guanajuato
Acoustically Levitated Whispering-Gallery Mode Microlasers, H. M. Reynoso-De La Cruz, E. D. Hernández-Campos, E. Ortiz-Ricardo, A. Martínez-Borquez, I. Rosas-Román, V. Contreras, G. Ramos-Ortiz, B. Mendoza-Santoyo, Cecilia Zurita-Lopez, R. Castro-Beltrán
Biology, Chemistry, and Environmental Sciences Faculty Articles and Research
Acoustic levitation has become a crucial technique for contactless manipulation in several fields, particularly in biological applications. However, its application in the photonics field remains largely unexplored. In this study, we implement an affordable and innovative phased-array levitator that enables stable trapping in the air of micrometer dye-doped droplets, thereby enabling the creation of microlasers. For the first time, this paper presents a detailed performance of the levitated microlaser cavity, supported by theoretical analysis concerning the hybrid technology based on the combination of whispering-gallery modes and acoustic fields. The pressure field distribution inside the acoustic cavity is numerically solved and …
Experiments With Monopoles, Rings And Knots In Spinor Bose-Einstein Condensates, 2023 University of Massachusetts Amherst
Experiments With Monopoles, Rings And Knots In Spinor Bose-Einstein Condensates, Alina A. Blinova
Doctoral Dissertations
Topological excitations are ubiquitous in nature, their charge being a naturally-quantized, conserved quantity that can exhibit particle-like behavior. Spinor Bose-Einstein condensates (BECs) are an exceptionally versatile system for the study and exploration of topological excitations. Between the spin-1 and spin-2 87Rb condensates there are seven possible broken-symmetry magnetic phases, with each one hosting unique opportunities for topological defects. We have created and observed several novel topological excitations in a spinor 87Rb BEC. In this dissertation I present and discuss three principal experimental findings: (1) The discovery of an Alice ring, or a half-quantum vortex ring, emerging from a …
Thermal Conductivity And Mechanical Properties Of Interlayer-Bonded Graphene Bilayers, 2023 University of Massachusetts Amherst
Thermal Conductivity And Mechanical Properties Of Interlayer-Bonded Graphene Bilayers, Afnan Mostafa
Masters Theses
Graphene, an allotrope of carbon, has demonstrated exceptional mechanical, thermal, electronic, and optical properties. Complementary to such innate properties, structural modification through chemical functionalization or defect engineering can significantly enhance the properties and functionality of graphene and its derivatives. Hence, understanding structure-property relationships in graphene-based metamaterials has garnered much attention in recent years. In this thesis, we present molecular dynamics studies aimed at elucidating structure-property relationships that govern the thermomechanical response of interlayer-bonded graphene bilayers.
First, we present a systematic and thorough analysis of thermal transport in interlayer-bonded twisted bilayer graphene (IB-TBG). We find that the introduction of interlayer C-C …
The Fate Of The Crossbridge After Phosphate Rebinding: Implications For Fatigue, 2023 University of Massachusetts Amherst
The Fate Of The Crossbridge After Phosphate Rebinding: Implications For Fatigue, Christopher P. Marang
Doctoral Dissertations
In response to repeated intense contractile activity, a muscle’s ability to generate force decreases due to the created state of muscular fatigue. This compromised force production state is dependent on changes within the microenvironment of muscle thought to alter the function of the force generating, contractile protein myosin. For example, phosphate (Pi), elevated during fatigue, has been suggested to alter how myosin generates force. However, the effects of Pi are not straightforward, as muscle fiber data suggest that Pi's interaction with myosin may be force-dependent. In particular, Pi has no effect on maximal shortening …
Equilibrium And Quench-Dynamical Studies Of Ultracold Fermions In Ring-Shaped Optical Traps, 2023 Dartmouth College
Equilibrium And Quench-Dynamical Studies Of Ultracold Fermions In Ring-Shaped Optical Traps, Daniel Gordon Allman
Dartmouth College Ph.D Dissertations
The unique capability to precisely tune the few and many-body configurations of
ultracold Fermi gases provides a multi-dimensional platform for studying novel, ex-
otic aspects of quantum systems. These aspects include superfluid/superconducting
phenomena supported by potentially exotic pairing mechanisms, non-equilibrium and
critical dynamics, and proposed quantum sensing or computing applications based on
atomtronics.
Ring geometries provide natural arenas for probing transport properties of super-
fluids. Metastable states of quantized superfluid flow —persistent currents— exhibit
remarkable properties, and the manner in which they form is an incredibly rich sub-
ject. Studies of quenched superfluids demonstrate that persistent currents can form
from …
Quantitative, Photocurrent Multidimensional Coherent Spectroscopy, 2023 University of Denver
Quantitative, Photocurrent Multidimensional Coherent Spectroscopy, Adam Halaoui
Electronic Theses and Dissertations
Multidimensional coherent spectroscopy (MDCS) is a quickly growing field that has a lot of advantages over more conventional forms of spectroscopy. These advantages all come from the fact that MDCS allows us to get time resolved correlated emission and absorption spectra using very precisely chosen interactions between the density matrix and the excitation laser. MDCS spectra gives the researcher a lot of information that can be extracted purely through qualitative analysis. This is possible because state couplings are entirely separated on the spectra, and once we know how to read the data, we can see how carriers transport in the …
Ferroelectric Hafnia Surface In Action, 2023 University of Nebraska-Lincoln
Ferroelectric Hafnia Surface In Action, Xia Hong
Nebraska Center for Materials and Nanoscience: Faculty Publications
Piezoresponse microscopy and spectroscopy reveal the inextricable role of surface electrochemistry in stabilizing and controlling ferroelectricity in doped hafnia.
Doped hafnia (HfO2), a relatively new member of the ferroelectric family, has challenged in many ways our conventional perception of ferroelectric oxides. It possesses extremely localized electric dipoles that are independently switchable,1 making it immune to finite size effects — the loss of long-range dipole order in ferroic materials due to size scaling. While polycrystalline grains and microstructures can yield lower polarization and poorer cycling behavior in canonical ferroelectrics such as Pb(Zr,Ti)O3 and BaTiO3, in …
Theoretical Framework Of Exchange Coupled Tripartite Spin Systems With Magnetic Anisotropy And Predictions Of Spin And Electronic Transport Properties For Their Use In Quantum Architectures, 2023 University of Central Florida
Theoretical Framework Of Exchange Coupled Tripartite Spin Systems With Magnetic Anisotropy And Predictions Of Spin And Electronic Transport Properties For Their Use In Quantum Architectures, Eric Switzer
Electronic Theses and Dissertations, 2020-
There has been significant interest in spin systems involving two or more coupled spins as a single logical qubit, particularly for scalable quantum computing architectures. Recent realizations include the so-called singlet-triplet qubits and coupled magnetic molecules. An important class of coupled-spin systems, the three-spin paradigm for spin greater than 1/2, has not yet been fully realized in scalable qubit architectures. In this thesis, I develop the theoretical framework to investigate a class of tripartite spin models for realistic systems. First, I model a spin 1/2 particle (e.g., an electron) and two spin 1 particles (in a dimer arrangement) coupled with …
Design And Fabrication Of A Trapped Ion Quantum Computing Testbed, 2023 University of Massachusetts Amherst
Design And Fabrication Of A Trapped Ion Quantum Computing Testbed, Christopher A. Caron
Masters Theses
Here we present the design, assembly and successful ion trapping of a room-temperature ion trap system with a custom designed and fabricated surface electrode ion trap, which allows for rapid prototyping of novel trap designs such that new chips can be installed and reach UHV in under 2 days. The system has demonstrated success at trapping and maintaining both single ions and cold crystals of ions. We achieve this by fabricating our own custom surface Paul traps in the UMass Amherst cleanroom facilities, which are then argon ion milled, diced, mounted and wire bonded to an interposer which is placed …
Anomaly Detection In The Molecular Structure Of Gallium Arsenide Using Convolutional Neural Networks, 2023 Air Force Institute of Technology
Anomaly Detection In The Molecular Structure Of Gallium Arsenide Using Convolutional Neural Networks, Timothy Roche *, Aihua W. Wood, Philip Cho *, Chancellor Johnstone
Faculty Publications
This paper concerns the development of a machine learning tool to detect anomalies in the molecular structure of Gallium Arsenide. We employ a combination of a CNN and a PCA reconstruction to create the model, using real images taken with an electron microscope in training and testing. The methodology developed allows for the creation of a defect detection model, without any labeled images of defects being required for training. The model performed well on all tests under the established assumptions, allowing for reliable anomaly detection. To the best of our knowledge, such methods are not currently available in the open …
High-Power Laser Cooling And Temperature-Dependent Fluorescence Studies Of Ytterbium Doped Silica, 2023 University of New Mexico
High-Power Laser Cooling And Temperature-Dependent Fluorescence Studies Of Ytterbium Doped Silica, Brian Topper
Optical Science and Engineering ETDs
Experimental observation of optical refrigeration using ytterbium doped silica glass in recent years has created a new solution for heat mitigation in high-power laser systems, nonlinear fiber experiments, integrated photonics, and precision metrology. Current efforts of different groups focus on compositional optimization, fiber fabrication, and investigating how much silica can be cooled with a laser. At the start of this work, the best effort in laser cooling ytterbium doped silica saw cooling by 6 K from room temperature. This dissertation follows the experimental efforts that culminated in the increase of this initial record by one order of magnitude. Comprehensive spectroscopic …