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Hot Electron Chemistry On Bimetallic Plasmonic Nanoparticles, Bryn E. Merrill, Bingjie Zhang, Jerry LaRue 2020 Chapman University

Hot Electron Chemistry On Bimetallic Plasmonic Nanoparticles, Bryn E. Merrill, Bingjie Zhang, Jerry Larue

Student Scholar Symposium Abstracts and Posters

Catalysis provides pathways for efficient and selective chemical reactions through the lowering of energy barriers for desired products. Gold nanoparticles (AuNP) show excellent promise as plasmonic catalysts. Localized surface plasmon resonances are oscillations of the electron bath at the surface of a nanoparticle that generate energetically intense electric fields and rapidly decay into energetically excited electrons. The excited electrons have the potential to destabilize strongly bound oxygen atoms through occupation of accessible anti-bonding orbitals. Tuning the anti-bonding orbitals to make them accessible for occupancy will be achieved by coating the AuNP in a thin layer of another transition metal, such …


240— Target Characterization Using Rutherford Backscattering Spectroscopy, Matthew G. Klein, Anthony C. Cooper, Jovahn A. Roumell 2020 SUNY Geneseo

240— Target Characterization Using Rutherford Backscattering Spectroscopy, Matthew G. Klein, Anthony C. Cooper, Jovahn A. Roumell

GREAT Day Posters

Rutherford backscattering spectroscopy (RBS) is a non-destructive ion-beam analytical technique that is used to determine properties of a target such as thickness, areal density, and elemental composition. This scattering is the result of Coulomb forces between the target atoms and the incident particle. The energy spectrum of the scattered ions depends on the atomic number of the target atoms as well as the target thickness.


1d Fluid Model Of Rf-Excited Cold Atmospheric Plasmas In Helium With Air Gas Impurities, Yifan Liu, Dingxin Liu, Jishen Zhang, Bowen Sun, Aijun Yang, Michael G. Kong 2020 Old Dominion University

1d Fluid Model Of Rf-Excited Cold Atmospheric Plasmas In Helium With Air Gas Impurities, Yifan Liu, Dingxin Liu, Jishen Zhang, Bowen Sun, Aijun Yang, Michael G. Kong

Bioelectrics Publications

Cold atmospheric plasmas (CAPs) in helium with air gas impurities (HeþAir for abbreviation) compromise the discharge stability of helium and the chemical reactivity of air, having great prospects for various applications such as plasma biomedicine. However, different kinds of reactive species are produced in HeþAir CAPs but only a few of them could be measured, and the plasma chemistry is so complex that the reported simulation models are simplified to a large extent, such as neglecting the space variation of CAPs by using a 0D model. As a result, much remains unknown for HeþAir CAPs, which hinders the development of …


Optimizing Llrf Parameters In The Electron-Ion Collider, William M. Bjorndahl 2020 California Polytechnic State University, San Luis Obispo

Optimizing Llrf Parameters In The Electron-Ion Collider, William M. Bjorndahl

Physics

To improve particle interaction in the future Electron-Ion Collider (EIC), we investigated different feedback implementations to control the accelerating voltage and examined the power and beam phase for each instance. Using MATLAB, we studied three feedback mechanisms: Direct, One Turn, and Feedforward. Enacting feedforward yielded the best performance. To minimize the klystron power consumption, we analyzed different Low-Level Radio Frequency (LLRF) parameters such as detuning. Combining theory and simulated results, we found the optimal detuning value that minimizes klystron power consumption.


Determining Bulk Aerosol Absorption From Off Axis Backscattering Using Rayleigh Beacon Laser Pulses, Julie C. Grossnickle 2020 Air Force Institute of Technology

Determining Bulk Aerosol Absorption From Off Axis Backscattering Using Rayleigh Beacon Laser Pulses, Julie C. Grossnickle

Theses and Dissertations

Aerosol absorption and scattering can play a key role in degrading high energy laser performance in the form of thermal blooming and beam attenuation. Aerosol absorption properties are not completely understood, and thus affect how we are able to quantify expected high energy laser weapon performance. The Air Force Institute of Technology Center for Directed Energy (AFIT CDE) developed both Laser Environmental Effects Definition and Reference (LEEDR) and the High Energy Laser End-to-End Operational Simulation (HELEEOS) code to characterize atmospheric radiative transfer effects and evaluate expected directed energy weapon system performance. These packages enable modeling of total irradiance at given …


Laser Shock Peening Pressure Impulse Determination Via Empirical Data-Matching With Optimization Software, Colin C. Engebretsen 2020 Air Force Institute of Technology

Laser Shock Peening Pressure Impulse Determination Via Empirical Data-Matching With Optimization Software, Colin C. Engebretsen

Theses and Dissertations

Laser shock peening (LSP) is a form of work hardening by means of laser induced pressure impulse. LSP imparts compressive residual stresses which can improve fatigue life of metallic alloys for structural use. The finite element modeling (FEM) of LSP is typically done by applying an assumed pressure impulse, as useful experimental measurement of this pressure impulse has not been adequately accomplished. This shortfall in the field is a current limitation to the accuracy of FE modeling, and was addressed in the current work. A novel method was tested to determine the pressure impulse shape in time and space by …


Laser Induced Thermal Degradation Of Carbon Fiber-Carbon Nanotube Hybrid Laminates, Joshua A. Key 2020 Air Force Institute of Technology

Laser Induced Thermal Degradation Of Carbon Fiber-Carbon Nanotube Hybrid Laminates, Joshua A. Key

Theses and Dissertations

Recent advancements in fiber laser technology have increased interest in target material interactions and the development of thermal protection layers for tactical laser defense. A significant material of interest is carbon fiber reinforced polymers due to their increased use in aircraft construction. In this work, the thermal response of carbon fiber-carbon nanotube (CNT) hybrid composites exposed to average irradiances of 0.87-6.8 W/cm2 were observed using a FLIR sc6900 thermal camera. The camera had a pixel resolution of 640x512 which resulted in a spatial resolution of 0.394x0.383 mm/pixel for the front and 0.463x0.491 mm/pixel for the back. The hybrid samples …


Conduction Mapping For Quality Control Of Laser Powder Bed Fusion Additive Manufacturing, Chance M. Baxter 2020 Air Force Institute of Technology

Conduction Mapping For Quality Control Of Laser Powder Bed Fusion Additive Manufacturing, Chance M. Baxter

Theses and Dissertations

A process was developed to identify potential defects in previous layers of Selective Laser Melting (SLM) Powder Bed Fusion (PBF) 3D printed metal parts using a mid-IR thermal camera to track infrared 3.8-4 m band emission over time as the part cooled to ambient temperature. Efforts focused on identifying anomalies in thermal conduction. To simplify the approach and reduce the need for significant computation, no attempts were made to calibrate measured intensity, extract surface temperature, apply machine learning, or compare measured cool-down behavior to computer model predictions. Raw intensity cool-down curves were fit to a simplified functional form designed to …


Cn And C2 Spectroscopy On The Pulsed Ablation Of Graphite In The Visible Spectrum, Brandon A. Pierce 2020 Air Force Institute of Technology

Cn And C2 Spectroscopy On The Pulsed Ablation Of Graphite In The Visible Spectrum, Brandon A. Pierce

Theses and Dissertations

An experimental study was conducted on the nanosecond pulsed laser ablation of graphite using a KrF laser at a fluence of 3.8 J/cm2 in Air, Ar, He, and N2. Optical emissions spectroscopy revealed the C2 Swan sequences and the CN Violet sequences. A spectroscopic model was developed to extract the molecular rotational and vibrational temperatures of each excited species for t=0.5-10 microseconds after laser irradiation. The rovibrational temperatures were found to vary with background gas for the CN Violet; however, only the vibrational temperature varied between He and the other background gases for C2 Swan. …


Si Nanocrystal Synthesis Via Double Implantation And Variable Implantation, James M. Gaudet 2020 The University of Western Ontario

Si Nanocrystal Synthesis Via Double Implantation And Variable Implantation, James M. Gaudet

Electronic Thesis and Dissertation Repository

Silicon (Si) nanocrystals (nc) precipitated from silicon-implanted silicon oxide (SiO2) are of interest as a novel light source for illumination, biomedical applications, optical computing, etc. They have some advantages over conventional III-V compound semiconductor nanocrystals produced by colloidal synthesis. They are compatible with Si/SiO2 based semiconductor processing, are stable, non-toxic at point of synthesis and consumption, and their luminescence falls with the infrared transmission window of biological materials. Unfortunately, synthesis of Si-nc embedded SiO2 is uneconomical and is not as amenable to precise control of the size distribution of nanocrystals as is the case for III-V …


Three-Dimensional Measurement Of Electron Temperature And Density In A Split Ring Resonator Microplasma, Neil Laya 2020 University of Alabama in Huntsville

Three-Dimensional Measurement Of Electron Temperature And Density In A Split Ring Resonator Microplasma, Neil Laya

Summer Community of Scholars Posters (RCEU and HCR Combined Programs)

No abstract provided.


Classifying Aurora Borealis: From Human Eyes To Machine Vision, Caleb Dowell 2020 University of Alabama in Huntsville

Classifying Aurora Borealis: From Human Eyes To Machine Vision, Caleb Dowell

Summer Community of Scholars Posters (RCEU and HCR Combined Programs)

No abstract provided.


Shape Tuning Of Silicon Nano-Tip Arrays Through Reactive Ion Etching For Cold Field Emission, Giridhar Tulasi Ram Sankabathula 2020 Northern Illinois University

Shape Tuning Of Silicon Nano-Tip Arrays Through Reactive Ion Etching For Cold Field Emission, Giridhar Tulasi Ram Sankabathula

Graduate Research Theses & Dissertations

Large area silicon nano-tip arrays have been predominantly used as cold cathode electron sources in the wide range of field emission applications. Various fabrication methodologies have been developed over the decades to obtain sharp-pointed field emitters. In this thesis, we mainly emphasized on reproducing high aspect ratio field emitters and to study their surface topographical changes encountered through reactive ion etching. A discrete set of high-density field emitters have been fabricated over the large area surfaces through a three-step nanofabrication process. The surface curvatures of the obtained emitter tips are finely tuned with multiple oxidation cycles to achieve a tip’s …


Birefringent Optofluidic Gratings, Sergio Calixto, JOSE L. GARCIA-CORDERO, DIANA F. CEDILLO-ALCANTAR, Izabela Naydenova, GUILLERMO GARNICA 2020 Centro de Investigaciones en Optica, Mexico

Birefringent Optofluidic Gratings, Sergio Calixto, Jose L. Garcia-Cordero, Diana F. Cedillo-Alcantar, Izabela Naydenova, Guillermo Garnica

Articles

A set of parallel microfluidic channels behaving as a diffraction grating operating in the Raman-Nath regime has been fabricated and studied. The diffraction efficiency of such structure can be tuned by selecting a liquid with a particular refractive index and/or optical anisotropy. Alternatively the optical properties of the liquid can be characterised by measuring the diffraction efficiency and the state of polarization of the diffracted beam. In this work, the microfluidic channels under study have been filled with penicillin molecules dissolved in water. Due to the chirality of the penicillin, the liquid has been found to have circular birefringence of …


Interfacial Current Distribution Between Helium Plasma Jet And Water Solution, Sui Wang, Dingxin Liu, Zifeng Wang, Yifan Liu, Qiaosong Li, Xiaohua Wang, Michael G. Kong, Mingzhe Rong 2020 Old Dominion University

Interfacial Current Distribution Between Helium Plasma Jet And Water Solution, Sui Wang, Dingxin Liu, Zifeng Wang, Yifan Liu, Qiaosong Li, Xiaohua Wang, Michael G. Kong, Mingzhe Rong

Bioelectrics Publications

The plasma-liquid interaction holds great importance for a number of emerging applications such as plasma biomedicine, yet a main fundamental question remains about the nature of the physiochemical processes occurring at the plasma-liquid interface. In this paper, the interfacial current distribution between helium plasma jet and water solution was measured for the first time by means of the splitting electrode method, which was borrowed from the field of arc plasma. For a plasma plume in continuous mode, it was found that the mean absolute current distribution at the plasma-liquid interface typically had an annular shape. This shape could be affected …


Control Of Charged Particle Dynamics And Electron Power Absorption Dynamics Utilizing Voltage Waveform Tailoring In Capacitively Driven Radio-Frequency Plasmas, Steven W. Brandt 2020 West Virginia University

Control Of Charged Particle Dynamics And Electron Power Absorption Dynamics Utilizing Voltage Waveform Tailoring In Capacitively Driven Radio-Frequency Plasmas, Steven W. Brandt

Graduate Theses, Dissertations, and Problem Reports

In this work, experimental measurements and analysis of numerical simulations are performed for capacitively coupled plasmas driven by tailored voltage waveforms under conditions which examine complicating factors present in industrial processes, including the influence of resonance effects, electronegative gases or gas mixtures, and plasma-surface interactions at a changing plasma-surface interface. Furthermore, the influence of different tailored voltage waveforms on the spatio-temporal electron power absorption, the generation of a DC self-bias, and on process relevant plasma parameters like ion energy distribution functions is investigated to provide a more complete understanding of the underlying fundamental plasma physics responsible for sustaining the discharge. …


Characterization Of A Plasma Source Simulating Solar Wind Plasma In A Vacuum Chamber, Blake Anthony Folta 2020 Missouri University of Science and Technology

Characterization Of A Plasma Source Simulating Solar Wind Plasma In A Vacuum Chamber, Blake Anthony Folta

Masters Theses

"The United States has set an aggressive time line to not only return to the Moon, but also to establish a sustained human presence. In the Apollo missions dust was a significant factor, but the duration of those missions was short so dust and surface charging were problems, but they did not pose an immediate threat. For a long-term mission, these problems instead become incredibly detrimental. Because of this, research needs to be conducted to investigate these phenomena so that mitigation techniques can be developed and tested. To this end, this thesis serves to demonstrate the Gas and Plasma Dynamics …


Attosecond-Pulse Metrology Based On High-Order Harmonic Generation, T. S. Sarantseva, M. V. Frolov, N. L. Manakov, A. A. Silaev, A. A. Romanov, N. V. Vvedenskii, Anthony F. Starace 2020 Voronezh State University

Attosecond-Pulse Metrology Based On High-Order Harmonic Generation, T. S. Sarantseva, M. V. Frolov, N. L. Manakov, A. A. Silaev, A. A. Romanov, N. V. Vvedenskii, Anthony F. Starace

Anthony F. Starace Publications

An all-optical method to retrieve the temporal intensity profile of an extreme ultraviolet (XUV) attosecond pulse is proposed based on XUV-assisted high-order harmonic generation (HHG) by an intense infrared (IR) pulse. For a harmonic located on the XUV-induced high-energy plateau (beyond the IR HHG plateau), the measured harmonic yield as a function of the time delay between the XUV and IR pulses is shown to accurately map the temporal intensity profile of the XUV pulse. Single-color and two-color orthogonal, linearly polarized IR pulses are used to demonstrate the method.


Minimizing The Duration Of Isolated Attosecond Pulses, Dian Peng, Anthony F. Starace, Hua-Chieh Shao, Jean Marcel Ngoko Djiokap 2020 University of Nebraska-Lincoln

Minimizing The Duration Of Isolated Attosecond Pulses, Dian Peng, Anthony F. Starace, Hua-Chieh Shao, Jean Marcel Ngoko Djiokap

Anthony F. Starace Publications

We investigate theoretically how the duration of an isolated attosecond pulse (IAP) can be minimized by carefully selecting frequencies of high-order harmonic generation (HHG) spectra produced by ultrashort driving laser pulses. Based on numerical calculations of HHG by solving the time-dependent Schrödinger equation for a single H atom, we provide three strategies for generating shorter IAPs. First, when the high-frequency region of an HHG plateau is selected one should use frequencies below the cutoff. Second, for a wide HHG plateau the low-frequency region can produce shorter IAPs than the high-frequency region. Third, we propose a method of producing IAPs with …


Origin Of The Multiphoton-Regime Harmonic-Generation Plateau Structure, Jean Marcel Ngoko Djiokap, Anthony F. Starace 2020 University of Nebraska-Lincoln

Origin Of The Multiphoton-Regime Harmonic-Generation Plateau Structure, Jean Marcel Ngoko Djiokap, Anthony F. Starace

Anthony F. Starace Publications

A physical interpretation is provided for the formation of the multiphoton-regime plateau feature in the spectra of nonlinear and correlated process of high-order harmonic generation (HHG) of two-active-electron atoms interacting with an intense linearly polarized laser field [Phys. Rev. A 88, 053412 (2013) for beryllium]. While in the strong-field tunneling regime the plateau feature is well known to be due to rescattering effects of the freed electron, its counterpart in the multiphoton regime is due to atomic resonance effects involving both singly excited states and doubly excited states. Here, we propose a strategy to uncover which kind of these states …


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