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Articles 1 - 11 of 11
Full-Text Articles in Physical Sciences and Mathematics
Ultrafast Spectroscopy Of Air Lasing In Filaments, Brian Robert Kamer
Ultrafast Spectroscopy Of Air Lasing In Filaments, Brian Robert Kamer
Optical Science and Engineering ETDs
Filamentation in air is a phenomenon that has been extensively investigated for the last two decades. At sufficiently high intensity, even air is a nonlinear medium. These intensities are reached with ultrashort pulses (50 to 100 fs) of more than 1 J energy, which self-focus in air, reach ionizing intensities of oxygen and nitrogen, creating a plasma that defocuses the beam. The air filament is a self-induced waveguide resulting from a balance of focusing and defocusing. In this work new techniques were developed to visualize and analyze this phenomenon through its emission, in particu- lar the UV emission of the …
The Profound Photophysical Effects Of Organic Chromophore Connectivity And Coupling, David J. Walwark Jr
The Profound Photophysical Effects Of Organic Chromophore Connectivity And Coupling, David J. Walwark Jr
Nanoscience and Microsystems ETDs
Through-bond and through-space interactions between chromophores are shown to have wide-ranging effects on photophysical outcomes upon light absorption in organic molecules. In collapsed poly(3-hexylthiophene), through-space coupling creates hybrid chromophores that act as energy sinks for nearby excitons and favorable sites for molecular oxygen to dock. Upon excitation with visible light the highly-coupled chromophores react with the docked oxygen and subsequently do not quench nearby excitons as efficiently. In tetramer arrays of perylene diimide chromophores the central moiety through-bond connectivity is synthesized in two variants which exhibit vastly different single-molecule blinking behavior and theoretically-predicted electronic transition character. In the more-connected tetramer …
Ultrasound Regulated Flexible Protein Materials: Fabrication, Structure And Physical-Biological Properties., Bowen Cai, Hanling Gu, Fang Wang, Kyle Printon, Zhenggui Gu, Xiao Hu
Ultrasound Regulated Flexible Protein Materials: Fabrication, Structure And Physical-Biological Properties., Bowen Cai, Hanling Gu, Fang Wang, Kyle Printon, Zhenggui Gu, Xiao Hu
Faculty Scholarship for the College of Science & Mathematics
Ultrasound can be used in the biomaterial field due to its high efficiency, easy operation, no chemical treatment, repeatability and high level of control. In this work, we demonstrated that ultrasound is able to quickly regulate protein structure at the solution assembly stage to obtain the designed properties of protein-based materials. Silk fibroin proteins dissolved in a formic acid-CaCl solution system were treated in an ultrasound with varying times and powers. By altering these variables, the silks physical properties and structures can be fine-tuned and the results were investigated with Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron …
Neutron Energy Tuning Assemblies For Nuclear Weapon Environment Applications At The National Ignition Facility, Nicholas J. Quartemont
Neutron Energy Tuning Assemblies For Nuclear Weapon Environment Applications At The National Ignition Facility, Nicholas J. Quartemont
Theses and Dissertations
An energy tuning assembly was developed to spectrally shape the National Ignition Facility deuterium-tritium fusion neutron source to a notional thermonuclear and prompt fission neutron spectrum to fulfill neutron source capability gaps. The experimental neutron environment was characterized with activation dosimetry, neutronics and covariance models, and unfolded to determine the as-fielded neutron spectrum. The first energy tuning assembly was demonstrated to create synthetic spectrally accurate post-detonation fission products, enhancing U.S. technical nuclear forensics capabilities. ATHENA, a second-generation energy tuning assembly, was also optimized to meet similar objectives, but the new platform neutron fluence efficiency was increased by a factor of …
Linear And Non Linear Properties Of Two-Dimensional Exciton-Polaritons, Mandeep Khatoniar
Linear And Non Linear Properties Of Two-Dimensional Exciton-Polaritons, Mandeep Khatoniar
Dissertations, Theses, and Capstone Projects
Technology has been accelerating at breakneck speed since the first quantum revolution, an era that ushered transistors and lasers in the late 1940s and early 1960s. Both of these technologies relied on a matured understanding of quantum theories and since their inception has propelled innovation and development in various sectors like communications, metrology, and sensing. Optical technologies were thought to be the game changers in terms of logic and computing operations, with the elevator pitch being "computing at speed of light", a fundamental speed limit imposed by this universe’s legal system (a.k.a physics). However, it was soon realized that that …
Optical Two-Dimensional Coherent Spectroscopy Of Many-Body Dynamics In Quantum Materials, Maria Fernanda Munoz
Optical Two-Dimensional Coherent Spectroscopy Of Many-Body Dynamics In Quantum Materials, Maria Fernanda Munoz
FIU Electronic Theses and Dissertations
Since the rise of the concept of quantum materials (QM), these materials described as many-body quantum systems (interacting atoms, molecules, or electrons) have been suitable for many optoelectronic and quantum applications. Additionally, there has been significant interest in the research of QM to understand the underlying physics behind their extraordinary optical properties. Examples of QM are ultracold atoms, layered 2D semiconductors, supramolecular materials, and more. In 2012, a high energy conversion efficiency of over 10% was reported for the first time for metal-halide perovskite (MHP) solar cells, opening a new era for photovoltaics research. The reported efficiencies have been improved …
Spectroscopic Properties Of Ferroic Superlattices, Shiyu Fan
Spectroscopic Properties Of Ferroic Superlattices, Shiyu Fan
Doctoral Dissertations
The interplay between charge, structure, magnetism, and orbitals leads to rich physics and exotic cross-coupling in multifunctional materials. Superlattices provide a superb platform to study the complex interactions between different degrees of freedom. In this dissertation, I present a spectroscopic investigation of natural and engineered superlattices including FexTaS2 and (LuFeO3)m/(LuFe2O4)1 under external stimuli of temperature and magnetic field as well as chemical substitution. Studying the phase transitions, symmetry-breaking, and complex interface interactions from a microscopic viewpoint enhances fundamental understanding of coupling mechanism between different order parameters and the …
High Frequency Electron Spin Resonance Investigations On Quasi-Two-Dimensional Chromium Halide Magnets, Christian Saiz
High Frequency Electron Spin Resonance Investigations On Quasi-Two-Dimensional Chromium Halide Magnets, Christian Saiz
Open Access Theses & Dissertations
Broadening the knowledge and understanding on the magnetic correlations in van der Waals layered magnets is critical in realizing their potential next-generation applications in devices such as spintronics. In this study, we employ high frequency (ν = 120 GHz, 240 GHz) electron spin resonance (ESR) spectroscopy on plate-like CrX3 (where X = Cl, Br, I) to gain insight into the magnetic interactions as a function of temperature (200 – 4.4 K) and the angle of rotation θ (degrees). We find that the temperature dependence of the ESR linewidth is well described by the Ginzburg-Landau critical model, indicative of antiferromagnetic correlations …
Investigation Of G Protein-Coupled Receptor Quaternary Structure Through Fluorescence Micro-Spectroscopy And Theoretical Modeling: Interdependence Between Receptor-Receptor And Receptor-Ligand Interactions, Joel David Paprocki
Theses and Dissertations
Proteins are of high interest in biophysics research due to the important roles they play within cells, such as sensing of chemical (ions and small molecules) and physical (e.g., light) stimuli, providing structure, transporting ions/molecules, signaling, and intercellular communication. The studies described in this dissertation focus on a particular type of membrane proteins known as G protein-coupled receptors (GPCR), which play a key role in cellular response to external stimuli. We used the sterile 2 α-factor mating pheromone receptor (Ste2), a prototypical class D GPCR present within Saccharomyces cerevisiae (baker’s yeast). Ste2 is responsible for initiating the second messenger signal …
Improved Λp Elastic Scattering Cross Sections Between 0.9 And 2.0 Gev/C As A Main Ingredient Of The Neutron Star Equation Of State, J. Rowley, N. Compton, C. Djalali, Krishna P. Adhikari, Dilini L. Bulumulla, Mohammad Hattawy, Sebastian E. Kuhn, Pushpa Pandey, Yelena Prok, M. Yurov, J. Zhang, Z. W. Zhao, Et Al., Clas Collaboration
Improved Λp Elastic Scattering Cross Sections Between 0.9 And 2.0 Gev/C As A Main Ingredient Of The Neutron Star Equation Of State, J. Rowley, N. Compton, C. Djalali, Krishna P. Adhikari, Dilini L. Bulumulla, Mohammad Hattawy, Sebastian E. Kuhn, Pushpa Pandey, Yelena Prok, M. Yurov, J. Zhang, Z. W. Zhao, Et Al., Clas Collaboration
Physics Faculty Publications
Strange matter is believed to exist in the cores of neutron stars based on simple kinematics. If this is true, then hyperon-nucleon interactions will play a significant part in the neutron star equation of state. Yet, compared to other elastic scattering processes, there is very little data on Λ-N scattering. This experiment utilized the CEBAF Large Acceptance Spectrometer (CLAS) detector to study the Λp→Λp elastic scattering cross section in the incident Λ momentum range 0.9-2.0 GeV/c. These are the first data on this reaction since the 1970s. The new cross sections have significantly better accuracy and precision than the existing …
Photoemission Investigation Of Topological Quantum Materials, Klauss M. Dimitri
Photoemission Investigation Of Topological Quantum Materials, Klauss M. Dimitri
Honors Undergraduate Theses
Topological insulators (TIs) are a class of quantum materials, which behave as insulators in the bulk, yet possess gapless spin-polarized surface states, which are robust against nonmagnetic impurities. The unique properties of TIs make them attractive not only for studying various fundamental phenomena in condensed matter and particle physics, but also as promising candidates for applications ranging from spintronics to quantum computation. Within the topological insulator realm, a great deal of focus has been placed on discovering new quantum materials, however, ideal multi-modal quantum materials have yet to be found. Here we study alpha-PdBi2, KFe2Te2, and DySb compounds including others …