Atomic, Molecular and Optical Physics Commons^™

Convergent Close-Coupling Approach To Electron Scattering On H3+ : Scattering Dynamics And Dissociative Processes, Reese K. Horton, Michael V. Pak, Igor Bray, Dmitry V. Fursa

Faculty Publications

Cross sections for electron impact dissociative excitation and ionization in scattering on vibrationally excited levels of the ground electronic state of H₃⁺, D₃⁺, and T₃⁺ are reported in the energy range of 8–1000 eV. Calculations have been performed using a newly developed version of the molecular convergent close-coupling code. Convergence of the cross sections with the size of the projectile partial-wave and close-coupling expansions is examined. Branching ratios and cross sections for the yields of D₂⁺ and D⁺ from dissociative excitation of D₃⁺ are presented and isotope …

Convergent Close-Coupling Approach To Electron Impact Dissociation Of The Polyatomic Molecule H 3 + And Its Isotopologues, Reese K. Horton, Michael V. Pak, Igor Bray, Dmitry V. Fursa

Faculty Publications

Cross sections for electron impact dissociative excitation and ionization in scattering on vibrationally excited levels of the ground electronic state of H₃⁺ and its isotopologues are reported in the energy range of 8 to 1000 eV. Calculations have been performed using a newly developed version of the molecular convergent close-coupling code. Cross sections for total dissociative excitation, ionization yielding atomic fragments such as D⁺, and the total inelastic cross section are presented. Good agreement with available experiments has been demonstrated.

Explorations Of Dna-Single-Walled Carbon Nanotube Interactions To Develop Multiplexed Molecularly Specific Biosensors For Inflammation, Amelia K. Ryan

Dissertations and Theses

Inflammatory cytokines such as interleukin-6 (IL-6) and interleukin-12 (IL-12) are central regulators of immune signaling and key biomarkers of disease, yet existing assays for their detection remain slow, invasive, and lack multiplexing ability. This dissertation advances the development of single-walled carbon nanotube (SWCNT) optical nanosensors capable of real-time, multiplexed, and molecularly specific cytokine detection through innovative use of single-stranded DNA (ssDNA) interfaces.

First, an IL-6-specific DNA aptamer was employed as both a dispersing agent and recognition probe for SWCNT fluorescence sensing. Sequence modifications, including anchor domains, truncations, and thermally induced refolding, were systematically tested to optimize sensitivity and selectivity. The …

Design And Construction Of An Affordable Adjustable Repetition Rate Optical Frequency Comb, Christopher Latchford

Physics, Astronomy and Geophysics Honors Papers

Two different adjustable repetition rate optical frequency combs were designed and constructed with off-the-shelf components, including several improvements to established erbium fiber designs. These designs were assembled at a fraction of the cost of a commercial comb. Both combs were constructed with a repetition rate of roughly 100 MHz, with one combs tuning range being 2 MHz and the others being 3 MHz. These combs followed different designs, the first being a modification of an established nonlinear polarization rotation (NPR) design, the second being a modification to a “figure 9” design. A stabilization control loop for frep achieved long-term drifts …

Quantum-Mechanical Definition Of The Classical Scalar Potential In Schrödinger-Pauli And Schrödinger Theory, Viraht Sahni

Publications and Research

According to the Bohr correspondence principle, the external temporal scalar potential in the classical equation of motion is replicated in quantum theory as a multiplicative operator. An equivalent quantum-mechanical definition of the scalar potential in Schrödinger-Pauli/Schrödinger theory is provided. The potential is a known universal functional of the wave function. At each instant of time, it is the work done in a conservative “classical” field representative of internal properties of the system: Pauli and Coulomb correlations, kinetic effects, the density, the Lorentz force, an internal magnetic component, and the current density response. The Hamiltonians are thus rewritten in a …

Collision-Induced Absorption Spectra Of N₂ And Ch₄, Ryan M. Johnson, Peter F. Bernath, Brant Billinghurst, Jianbao Zhao

Chemistry & Biochemistry Faculty Publications

Collision-induced spectra are essential for radiative transfer modeling of Titan's atmosphere. We present experimental spectra of nitrogen–methane mixtures with an accompanying fit of N₂-CH₄ collision-induced absorption in the 30–400 cm⁻¹ region at about 130 K. We found a peak absorption of 2.30 × 10⁻⁵ cm⁻¹ amagat⁻² at 75 cm⁻¹ and a secondary peak of 1.35 × 10⁻⁵ c⁻¹ amagat⁻² at 206.5 cm⁻¹, which agrees with previous studies. Our work does not support the suggestion that N₂-CH₄ CIA in the far-infrared should be increased by about 50%, as suggested by spectroscopic modeling of Titan using data from A. Borysow & C. …

Momentum Imaging Of Electrons And Recoil Ions From Anion-Neutral Interactions In A Cryogenic Ion Storage Ring, F. Herrmann, W. Zhang, M. Schulz, D. V. Chicharro, A. Dorn, M. Grieser, F. Grussie, H. Kreckel, O. Novotny, F. Trost, A. Wolf, T. Pfeifer, C. D. Schröter

Physics Faculty Research & Creative Works

We have momentum-analyzed electrons and recoil ions in triple coincidence with projectiles neutralized in 300-keV Si-+Ar collisions. The experiment was performed at a cryogenic ion storage ring with an in-ring reaction microscope. Differential momentum distributions for detachment with simultaneous target ionization were obtained. At more than 15% of the detachment-only rate the ionization rate is surprisingly large. A correlated two-electron channel is found to be dominant. This is also unexpected because the projectile energy is well below the threshold for the correlated process.

A Distorted-Wave Approach To The Elastic Scattering Of Twisted Electrons, Allison Harris, Stephan Fritzsche

Faculty publications – Physics

The elastic scattering of spinless vortex electrons on realistic target atoms has been investigated. In particular, expressions are derived in different approximations for the angular distribution of elastically scattered electrons. We develop a distorted wave formalism that includes the effect of the atomic potential on the impinging vortex electron and compare this to a plane-wave Born approximation (PWBA) without such a distortion. Detailed computations have been performed for elastic scattering of vortex electrons on helium, neon, and argon targets by varying the energy, topological charge, and opening angle. Our results show that the overall magnitude of the angular distribution of …

Entangled Photoelectron Attosecond Spectroscopy, Jonathan Sar-Shalom

Honors Undergraduate Theses

In this thesis we propose an interferometric scheme to retrieve the dynamics of an electron wave packet emitted from two distinct residual photo-ion channels in the ionization of an atom by an ultra-short UV pulse. EPAS (Entangled-Photoelectron Attosecond Spectroscopy) works by having a non-overlapping UV and few-cycle IR pulse, where the IR is tuned near the transition frequency between two electronic bound states of the photo-ion. Using a time-dependent simulation based on a two-channel atomic model, supported by a perturbative approach, we were able to compute the resulting interference in the angular distribution of the photoelectron and retrieve the energy-dependent …

Investigation Of Colorimetric Trends In Rare-Earth Co-Doped Ypo₄, Barit K. Essman

All Master's Theses

From detectors in scientific instrumentation to medical imaging devices and nuclear monitoring systems to LEDs seen in consumer products, phosphors are utilized in a myriad of applications experienced by both the general public and scientific community alike. For many phosphor applications, emission color and intensity are notably important features to consider. When phosphors are co-doped with rare-earth activators, the ability to predict emission intensity and color output becomes challenging due to competition kinetics and energy transfer between the dopants. During this study, correlation between trends in co-doped phosphor excitation and color output were analyzed to interpret optical behaviors originating from …

Effect Of Reduction Annealing On The Structural And Electrical Properties Of Α-Moo3 Thin Films, Sandipani Ghosh

Graduate Theses/Dissertations

2D layered molybdenum oxide has attracted significant research interest due to its tuneable bandgap and diverse structural, chemical, electrical, and optical properties influenced by growth parameters and synthesis techniques. In this study, the effects of reduction annealing on the structural and electrical properties of few-layer MoO₃ thin films, deposited on Si/SiO₂ substrates via pulsed laser deposition, were investigated. X-ray diffraction revealed nanocrystalline structures with a preferred (020) orientation, reduction annealing produced highly crystalline orthorhombic α-MoO₃ with reduced unit cell volume. FESEM/EDS provided detailed analyses of microstructures and elemental compositions. Raman spectroscopy confirmed the orthorhombic structure, with characteristic peaks at 667, …

Interactions And Applications Of Optical Angular Momentum In Magneto-Optical Material, Seth R. Nelson

Dissertations, Master's Theses and Master's Reports

This dissertation explores the interactions and applications of optical angular momentum within magneto-optical materials. Beginning with a theoretical and experimental analysis of multiple reflection and refraction phenomena within magneto-optical material. We derive and verify the dependence of refractive indices on optical spin angular momentum and magneto-optical magnetization, resulting in nonreciprocal elliptical and linear polarization beam splitting effects and wavevector discretization. We fabricate a magnetless slab waveguide isolator with minimal optical loss. Extending our study to optical orbital angular momentum, we introduce a perturbation to the electronic transition model in bismuth-substituted iron garnets. We demonstrate that this perturbation leads to nonreciprocal …

Formation Of Pyramidal Palladium Enhanced By B(C₆F₅)₃ Additive Enabling Selective Alkene Monoisomerization, Paul D. Miller, Trandon A. Bender

Chemistry & Biochemistry Faculty Publications

The addition of a strong Lewis acid, tris(pentafluorophenyl)borane, facilitates the reduction of Pd(cod)Cl₂ with Et₃SiH to form palladium nanoparticles in organic solvents. It was found that these palladium nanoparticles are capable of selective monoisomerization of linear alkenes. This heterogeneous palladium catalyst is tolerant of a wide variety of functional groups, confirmed by substrate and robustness screenings. It is also possible to utilize poly(methylhydro)siloxane, an industrial waste byproduct, as the reductant to enable similar isomerization chemistry.

Periodic Trends In The Electronic And Magnetic Structure Of Superatomic 3d Transition Metal Chalcogenide Clusters, Gabriel Bohannon

Theses and Dissertations

We have systematically investigated the electronic structure of octahedral transition metal chalcogenide clusters, TM₆S₈(CO)₆, in which the transition metal atoms are from the 3d series in order to identify if periodic properties emerge. We were motivated by the identification of closed electronic shells with electron counts of 96, 100 and 114 in similar clusters from the 4d and 5d transition metal series. Further motivation was the finding of a dual-shell closing in the Fe₆S₈(CN)₆^5- cluster. This cluster is stabilized with a large spin magnetic moment due to the …

Applying The Lagrangian Variational Method To Atom Interferometry, Jeffrey W. Heward

College of Graduate Studies: Theses & Dissertations

Atom interferometry in Bose-Einstein condensate systems has emerged as a promising technique for precision metrology. The dynamics of these systems are well-described by the Gross-Pitaevskii equation (GPE), but direct numerical solution of this equation is infeasible for realistic systems. We use the Lagrangian Variational Method (LVM) to approximate solutions of the GPE in 1D and 3D, and we compare the LVM results to the exact solutions. We also present 3D LVM results for a case where numerical solution of the GPE is infeasible.

Synthesis And Characterization Of Doped Rare-Earth Zinc Alloys, Partha Das

Graduate Theses/Dissertations

Rare-Earth-Zinc (RE-Zn) alloys doped with manganese represent a promising class of materials with diverse applications in magnetic, electronic, and thermoelectric devices. These alloys hold significant potential owing to the unique combination of rare-earth elements' properties with the versatility of zinc, augmented by manganese doping. In this study, I present the successful synthesis of ErMn_0.2Zn_11.8 alloys, achieved through self-flux method. The synthesized crystals were characterized using electron dispersive spectroscopy (EDS) and single crystal X-ray diffraction (XRD). Additionally, magnetic measurements were performed to investigate the magnetic properties. Future plans include DFT calculations and comparison study between Rare-Earth-Zinc alloys with …

Photoionization Of Spin-Polarized Rydberg Atoms Out Of A Continuous Wave Optical Dipole Trap, Kevin Lee Romans

Doctoral Dissertations

"Recent research has demonstrated the need for a fully differential experiment on the photoionization of ⁶Li Rydberg atoms in a continuous wave (cw) laser field, as this would provide a new path forward for studying never before accessible atom-light interactions. Rydberg atoms are back in the focus of intense research due to their peculiar properties, which make them interesting candidates for quantum optics and information applications. In this work, we study the ionization of such Rydberg atoms, due to their interaction with a trapping laser field, by utilizing a reaction microscope (ReMi) capable of measuring photoelectron momentum distributions with …

Laser–Assisted Free–Free (Laff) Electron Scattering: An Elastic Angular Distribution In Argon And The Use Of A Novel Pulsed-Laser Multipass System In Laff Experiments, Charles M. Weaver

Theses and Dissertations--Physics and Astronomy

Laser–assisted free–free experiments investigate the emission or absorption of photons when an electron scatters from an atom in the presence of a laser field.

We measured the relative differential cross sections for 350 eV electrons scattered by an argon target in the presence of 1.17 eV photons from a Nd:YAG laser. The angular distribution for elastically scattered 350 eV electrons was measured over scattering angles from 4◦ to 80◦. This distribution exhibits a pronounced maximum near 47◦ and is symmetric about this angle, as predicted by a Kroll–Watson approximation (KWA) calculation for the experimental kinematics. These measurements directly test a …

Reconstructing Superoscillations Buried Deeply In Noise, Derek D. White, Shunxing Zhang, Barbara Šoda, Achim Kempf, Daniele C. Struppa, Andrew N. Jordan, John C. Howell

Mathematics, Physics, and Computer Science Faculty Articles and Research

We utilize a method using frequency combs to construct waves that feature superoscillations—local regions of the wave that exhibit a change in phase that the bandlimits of the wave should not otherwise allow. This method has been shown to create superoscillating regions that mimic any analytic function—even ones well outside the bandlimits—to an arbitrary degree of accuracy. We experimentally demonstrate that these waves are extremely robust against noise, allowing for accurate reconstruction of a superoscillating target function thoroughly buried in noise. We additionally show that such a construction can be easily used to range-resolve a signal well below the commonly …

Modeling Of Light Filamentation For Nonlinear Imaging And Waveguiding, Nicholas Bagley

Mathematics Theses and Dissertations

Ultrashort pulses are capable of extremely high powers; in addition to enabling various applications in defense, sensing, and imaging, they provide a useful arena in which to study nonlinear optical phenomena that are observable only at high intensities. Due to these effects, which can include ionization and thermal blooming, simulation of ultrashort pulse propagation is a complicated multiphysics problem. We provide an overview of techniques used to simulate the propagation of ultrashort pulses in the nonlinear regime, including the formation of light filaments due to the competition of Kerr self-focusing and defocusing (e.g. via plasma generation). We discuss both carrier-resolved …

Effect Of Temperature And Rhenium Content In Precipitates On Dispersion Hardening Of Tungsten, Yulia R. Sharapova, Arseny M. Kazakov, Elena A. Korznikova, Alexandr Zinovev, Dmitry Terentyev, Sergey V. Dmitriev

Karbala International Journal of Modern Science

Tungsten (W) is being developed as a plasma-facing material for fusion reactors, where it is subjected to MeV neutron irradiation, low-energy helium isotope particles, and high temperatures. These conditions lead to the formation of point defects, dislocation loops, voids, and transmutation into rhenium (Re) and osmium (Os), which form precipitates that significantly impact dislocation motion and increase hardness. This study uses molecular dynamics modeling to examine the interaction between an edge dislocation and Re-rich particles of various stoichiometries, specifically coherent bcc-phase particles and noncoherent σ-phase precipitates. Results show that shear stress increases by approximately 20-40% with larger particle size (3-5 …

Beamed: A Bench For Automated Measurements Of Electrical Discharges - A New Standard For Paschen Curves, Jared Nelson

Doctoral Dissertations and Master's Theses

The initiation of electrical discharges, particularly glow discharges, plays a significant role in industry and environmental science, affecting systems such as electronics, power grids, and atmospheric phenomena. Despite extensive studies and applications of Paschen's law, current methodologies for experimental Paschen tests in direct current (DC) conditions lack standardized practices. This thesis presents the development and validation of a DC-based standard for electrical discharge initiation, using the BEnch for Automated Measurements of Electrical Discharges (BeAMED). BeAMED is designed to standardize the experimental process by automating electrical discharges' initiation and data acquisition. The autonomous nature of the system provides insights into the …

Characterizing 2d Materials Using Positron Impact Induced Electron Spectroscopy And Development Of A Novel Thin Film Zno Based Piezo-Photonic Detector For Cryogenic And Mems Applications, Pratyanik Sau

2024 Fall Honors Capstone Projects - Archive

Surface analytical techniques are essential for engineering nano-detectors allowing characterization of their chemical composition, electromechanical properties, and physical structure. In the first chapter, the positron impact-induced secondary electron (PIISE) energy spectra and yield from single-layer graphene (SLG) and multi-layer graphene (MLG) grown on a polycrystalline Cu substrate have been presented. In the second chapter, an extensive catalog of Positron Induced Auger Spectra is presented to aid in the analysis of elemental composition of various materials. Additionally, in the third chapter, a novel detection scheme utilizing the piezo-pyroelectric properties of Zinc Oxide (ZnO) thin films have been demonstrated for its application …

Graphene-Based Antennas Utilizing Polyvinylidene Fluoride (Pvdf) Substrates For Attenuation, Josef Frankhouse

Mechanical Engineering Undergraduate Honors Theses

In this study, a Terahertz (THz) band antenna which can regulate its own resonant frequency without the requirement of manual adjustment is simulated. A polyvinylidene fluoride (PVDF) substrate is applied onto a rectangular graphene patch antenna. With a voltage potential applied onto the PVDF, the patch antenna can attenuate its frequency by physically changing the shape of the antenna, and in turn its resonant frequency. These antennas are within a 0.1 THz band between 1.32 THz to 1.22 THz measured from a radial bend of a flat surface to r = 75 , fitting into a return loss (S_{11 …}

A Simple And Low-Cost Method For Generating Short Laser Pulses, Daniel Fisher

Undergraduate Research Symposium Posters

A simple, portable method is described and demonstrated for generating short optical pulses (~ 1 μsec) from a continuous wave (CW) source using a rotating pinhole. A CW 633nm HeNe beam was focused onto a 225 μm diameter stainless steel pinhole, which was rotated up to 1000 Hz using an optical chopper wheel. The pulsed light was then focused onto a silicon photodetector and read by an oscilloscope. This novel setup aims to bridge the gap between pulsed laser performance and price for wide application in spectroscopy methods, industrial laser peening, and medical treatments. This will be the first publication …

Computational Design Of Complex Concentrated Alloys, Hamid Sharifi

Doctoral Dissertations

A high-throughput parameterization of modified embedded atom model (MEAM) interatomic potentials for combinations of Cu, Ti, Ni, Cr, Co, Al, Fe, and Mn was carried out using a genetic algorithm. Unary systems were parameterized based on DFT calculations and experimental results. MEAM potentials for 28 binary and 56 ternary combinations of the elements were parameterized to DFT results that were carried out with semi-automated frameworks. Specific attention was made to reproduce properties that impact compositional segregation, material strength, and mechanics. Utilizing the MEAM interatomic potentials and a Monte Carlo scheme, phase segregation in the CrNiCo, CuNiCr and CuNiCo fcc alloys …

Scalable Methods For Performant Control Of Hyperfine Qubits In Atoms And Ions, Matthew N. H. Chow

Physics & Astronomy ETDs

Qubits encoded within internal energy levels of atoms and ions have been used to demonstrate high-performance primitives of quantum computing for small numbers of qubits. Yet, the path to achieving sufficient size and fidelity for useful fault-tolerant quantum computation remains daunting. In this dissertation, I present several techniques I developed as steps along this path. These results include high-fidelity, low-loss detection for alkali atoms in optical tweezers, crosstalk-mitigated parallel one-qubit gates, robust entangling gates on trapped ions, and leakage-to-erasure conversion for non-destructive detection of atom loss errors. Through this collection of techniques, I have sought to make full use of …

Quantum Many-Body Scars In Few-Body Dipole-Dipole Interactions, Sarah E. Spielman, Alicia Handian, Nina P. Inman, Thomas J. Carroll, Michael W. Noel

Physics and Astronomy Faculty Publications

We simulate the dynamics of Rydberg atoms resonantly exchanging energy via two-, three-, and four-body dipole-dipole interactions in a one-dimensional array. Using simplified models of a realistic experimental system, we study the initial-state survival probability, mean level spacing, spread of entanglement, and properties of the energy eigenstates. By exploring a range of disorders and interaction strengths, we find regions in parameter space where the three- and four-body dynamics either fail to thermalize or do so slowly. The interplay between the stronger hopping and weaker field-tuned interactions gives rise to quantum many-body scar states, which play a critical role in slowing …

Experimental Characterization, Computational Investigation, And Structure-Property–Activity Relationship Studies Of Nickel Ferrite Nanostructures, Ali Ben Ahmed

Polytechnic Journal

Intending to predict the multifunctionality of Nickel ferrite in several technological and medical fields, we have prepared nickel ferrite nanostructure by coprecipitation method. X-ray Diffraction (XRD) is used to determine the crystalline structure and phase composition of materials by analyzing the pattern of X-rays scattered by the atoms within the material. Fourier Transform Infrared Spectroscopy (FTIR) provides information about a material's chemical bonds and functional groups by analyzing how it absorbs infrared light at various wavelengths. Scanning Electron Microscopy (SEM) offers high-resolution images of the material's surface morphology and texture by scanning it with a focused beam of electrons. Transmission …

Super-Resolution Magnetic Microscopy And Earth’S Field Magnetometry With Color Centers In Diamond, Nazanin Mosavian

Optical Science and Engineering ETDs

In recent years, the negatively charged nitrogen- vacancy (NV) center has emerged as a promising solid-state color center capable of measuring magnetic fields with high sensi- tivity and spatial resolution under ambient conditions. In this thesis I will discuss how we perform super resolution magnetic microscopy and acquire magnetic field images of nanoparticle samples at 100 nm resolution. I will explain how 3D flux concentrators increase magnetic field amplitude and allows us to measure vector component magnetic fields as low as 50 µT with a diamond magnetometer, without the use of an additional bias magnetic field. I also describe how …