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Study Of The Geometric Structure Of Low-Atomic Copper Clusters Using Computer Simulation, Nodirbek Ikromjonovich Ibrokhimov 2021 Ferghana Polytechnic Institute

Study Of The Geometric Structure Of Low-Atomic Copper Clusters Using Computer Simulation, Nodirbek Ikromjonovich Ibrokhimov

Scientific-technical journal

In this work, we investigated the geometric structure of small neutral copper clusters with low energy using the MD (Molecular Dynamics) method. When calculating the processes of interatomic interaction, we used a potential EAM (Embedded-atom method). A computer model of Cun (n = 2-13) clusters has been created. The geometric shapes of the Cu2, Cu3, Cu4, Cu5, Cu6, Cu7, Cu8, Cu9, Cu10, Cu11, Cu12, and Cu13 clusters have been studied and the structural parameters (Cu-Cu bond …


Quantum State Tomography Of Molecules By Ultrafast Diffraction, Ming Zhang, Shuqiao Zhang, Yanwei Xiong, Hankai Zhang, Anatoly A. Ischenko, Oriol Vendrell, Xiaolong Dong, Xiangxu Mu, Martin Centurion, Haitan Xu, R. J.Dwayne Miller, Zheng Li 2021 Peking University

Quantum State Tomography Of Molecules By Ultrafast Diffraction, Ming Zhang, Shuqiao Zhang, Yanwei Xiong, Hankai Zhang, Anatoly A. Ischenko, Oriol Vendrell, Xiaolong Dong, Xiangxu Mu, Martin Centurion, Haitan Xu, R. J.Dwayne Miller, Zheng Li

Martin Centurion Publications

Ultrafast electron diffraction and time-resolved serial crystallography are the basis of the ongoing revolution in capturing at the atomic level of detail the structural dynamics of molecules. However, most experiments capture only the probability density of the nuclear wavepackets to determine the time-dependent molecular structures, while the full quantum state has not been accessed. Here, we introduce a framework for the preparation and ultrafast coherent diffraction from rotational wave packets of molecules, and we establish a new variant of quantum state tomography for ultrafast electron diffraction to characterize the molecular quantum states. The ability to reconstruct the density matrix, which …


Voltage Controlled Néel Vector Rotation In Zero Magnetic Field, Ather Mahmood, Will Echtenkamp, Mike Street, Jun Lei Wang, Shi Cao, Takashi Komesu, Peter Dowben, Pratyush Buragohain, Haidong Lu, Alexei Gruverman, Arun Parthasarathy, Shaloo Rakheja, Christian Binek 2021 University of Nebraska–Lincoln

Voltage Controlled Néel Vector Rotation In Zero Magnetic Field, Ather Mahmood, Will Echtenkamp, Mike Street, Jun Lei Wang, Shi Cao, Takashi Komesu, Peter Dowben, Pratyush Buragohain, Haidong Lu, Alexei Gruverman, Arun Parthasarathy, Shaloo Rakheja, Christian Binek

Peter Dowben Publications

Multi-functional thin films of boron (B) doped Cr2O3 exhibit voltage-controlled and nonvolatile Néel vector reorientation in the absence of an applied magnetic field, H. Toggling of antiferromagnetic states is demonstrated in prototype device structures at CMOS compatible temperatures between 300 and 400 K. The boundary magnetization associated with the Néel vector orientation serves as state variable which is read via magnetoresistive detection in a Pt Hall bar adjacent to the B:Cr2O3 film. Switching of the Hall voltage between zero and non-zero values implies Néel vector rotation by 90 degrees. Combined magnetometry, spin resolved inverse …


Sigesn Light-Emitting Devices: From Optical To Electrical Injection, Yiyin Zhou 2021 University of Arkansas, Fayetteville

Sigesn Light-Emitting Devices: From Optical To Electrical Injection, Yiyin Zhou

Graduate Theses and Dissertations

Si photonics is a fast-developing technology that impacts many applications such as data centers, 5G, Lidar, and biological/chemical sensing. One of the merits of Si photonics is to integrate electronic and photonic components on a single chip to form a complex functional system that features compact, low-cost, high-performance, and reliability. Among all building blocks, the monolithic integration of lasers on Si encountered substantial challenges. Si and Ge, conventional epitaxial material on Si, are incompetent for light emission due to the indirect bandgap. The current solution compromises the hybrid integration of III-V lasers, which requires growing on separate smaller size substrates …


Ultrafast Magnetic Entropy Dynamics With Time-Resolved Pump-Probe Magneto-Optical Technique., Sahar Goharshenasanesfahani 2021 University of Louisville

Ultrafast Magnetic Entropy Dynamics With Time-Resolved Pump-Probe Magneto-Optical Technique., Sahar Goharshenasanesfahani

Electronic Theses and Dissertations

It has been observed that ultrathin films, multilayers, or magnetic nanostructures indicate novel magnetic phenomena that differ profoundly from the respective bulk properties. Besides, because of the broad applications of these magnetic materials in the industry, they are an exciting research area. Hence, investigating the low-dimensional magnetic systems is one of the most active fields in experimental condensed matter physics. Magnetization dynamics can occur over a wide range of time scales (from seconds to femtoseconds). Some of these processes even occur on time scales as short as a few picoseconds (10-12s) or femtoseconds (10-15s). Measurement of …


Development Of A Magnetic Confinement Attachment For Enhanced Signal In Handheld Laser Induced Breakdown Spectroscopy Soil Analysis, Alfred C. Anderson 2021 Jr.

Development Of A Magnetic Confinement Attachment For Enhanced Signal In Handheld Laser Induced Breakdown Spectroscopy Soil Analysis, Alfred C. Anderson

Theses and Dissertations

Field techniques for characterizing low levels of heavy elements of less than 100 parts per million in soils tend to be unreliable because of the relatively weak signal of these elements and the large, variable background inherent to analyzing soils with minimal sample preparation. To enhance the detection and analysis capability of a handheld laser-induced breakdown spectroscopy (LIBS) instrument, this work investigates the effects of a unique magnetic confinement apparatus on signal intensities, focusing on five iron lines as well as those from actinides in 11 soil samples. The proposed magnetic confinement apparatus achieved over 0.8 T but did not …


Parity-Time Symmetry In A Coherent Atomic Medium, Jingliang Feng 2021 University of Arkansas, Fayetteville

Parity-Time Symmetry In A Coherent Atomic Medium, Jingliang Feng

Graduate Theses and Dissertations

Parity-time (PT) symmetry has attracted considerable attention since optics was realized with the ability to provide a fertile platform for the exploration of PT symmetry. Although many of the previous researches on PT symmetry have been conducted in solid-state system and the network of fiber loops, coherent atomic medium offers another platform for the exploration of PT symmetry due to its easy reconfigurability and flexible tunability in parameters.

This dissertation mainly focuses on the investigations of the phenomena related to PT-symmetric optical lattice in a coherent atomic medium. First, a controllable photonic crystal with periodic Raman gain was constructed in …


Ferromagnetic Resonances In Single-Crystal Yttrium Iron Garnet Nanofilms Fabricated By Metal-Organic Decomposition, Szu Fan Wang, Kayetan Chorazewicz, Suvechhya Lamichhane, Ronald A. Parrott, Stefano Cabrini, Peter Fischer, Noah Kent, John H. Turner, Takayuki Ishibashi, Zachary Parker Frohock, Jacob J. Wisser, Peng Li, Ruthi Zielinski, Bryce Herrington, Yuri Suzuki, Mingzhong Wu, Keiko Munechika, Carlos Pina-Hernandez, Robert Streubel, Allen A. Sweet 2021 University of California, Berkeley

Ferromagnetic Resonances In Single-Crystal Yttrium Iron Garnet Nanofilms Fabricated By Metal-Organic Decomposition, Szu Fan Wang, Kayetan Chorazewicz, Suvechhya Lamichhane, Ronald A. Parrott, Stefano Cabrini, Peter Fischer, Noah Kent, John H. Turner, Takayuki Ishibashi, Zachary Parker Frohock, Jacob J. Wisser, Peng Li, Ruthi Zielinski, Bryce Herrington, Yuri Suzuki, Mingzhong Wu, Keiko Munechika, Carlos Pina-Hernandez, Robert Streubel, Allen A. Sweet

Robert Streubel Papers

Tunable microwave and millimeter wave oscillators and bandpass filters with ultra-low phase noise play a critical role in electronic devices, including wireless communication, microelectronics, and quantum computing. Magnetic materials, such as yttrium iron garnet (YIG), possess ultra-low phase noise and a ferromagnetic resonance tunable up to tens of gigahertz. Here, we report structural and magnetic properties of single-crystal 60 and 130 nm-thick YIG films prepared by metal-organic decomposition epitaxy. These films, consisting of multiple homoepitaxially grown monolayers, are atomically flat and possess magnetic properties similar to those grown with liquid-phase epitaxy, pulsed laser deposition, and sputtering. Our approach does not …


Conformer-Specific Photochemistry Imaged In Real Space And Time, E. G. Champenois, D. M. Sanchez, J. Yang, J. P. Figueira Nunes, A. Attar, Martin Centurion, R. Forbes, M. Gühr, K. Hegazy, F. Ji, S. K. Saha, Y. Liu, M. F. Lin, D. Luo, B. Moore, X. Shen, M. R. Ware, Xijie Wang, T. J. Martínez, Thomas J. A. Wolf 2021 SLAC National Accelerator Laboratory

Conformer-Specific Photochemistry Imaged In Real Space And Time, E. G. Champenois, D. M. Sanchez, J. Yang, J. P. Figueira Nunes, A. Attar, Martin Centurion, R. Forbes, M. Gühr, K. Hegazy, F. Ji, S. K. Saha, Y. Liu, M. F. Lin, D. Luo, B. Moore, X. Shen, M. R. Ware, Xijie Wang, T. J. Martínez, Thomas J. A. Wolf

Martin Centurion Publications

Conformational isomers (conformers) of molecules play a decisive role in biology and organic chemistry. However, experimental methods for investigating chemical reaction dynamics are typically not conformersensitive. We report on a gas-phase megaelectronvolt ultrafast electron diffraction investigation of a-phellandrene undergoing an electrocyclic ring-opening reaction. We directly imaged the evolution of a specific set of a-phellandrene conformers into the product isomer predicted by the Woodward-Hoffmann rules in real space and time. Our experimental results are in quantitative agreement with nonadiabatic quantum molecular dynamics simulations, which provide considerable detail of how conformation influences the time scale and quantum efficiency of photoinduced ring-opening reactions. …


Wave Function Identity: A New Symmetry For 2-Electron Systems In An Electromagnetic Field, Marlina Slamet, Viraht Sahni 2021 Sacred Heart University

Wave Function Identity: A New Symmetry For 2-Electron Systems In An Electromagnetic Field, Marlina Slamet, Viraht Sahni

Publications and Research

Stationary-state Schrödinger-Pauli theory is a description of electrons with a spin moment in an external electromagnetic field. For 2-electron systems as described by the Schrödinger-Pauli theory Hamiltonian with a symmetrical binding potential, we report a new symmetry operation of the electronic coordinates. The symmetry operation is such that it leads to the equality of the transformed wave function to the wave function. This equality is referred to as the Wave Function Identity. The symmetry operation is a two-step process: an interchange of the spatial coordinates of the electrons whilst keeping their spin moments unchanged, followed by an inversion. The Identity …


Magnetic Field Perturbations To A Soft X-Ray-Activated Fe (Ii) Molecular Spin State Transition, Guanhua Hao, Alpha T. N’diaye, Thilini K. Ekanayaka, Ashley S. Dale, Xuanyuan Jiang, Esha Mishra, Corbyn Mellinger, Saeed Yazdani, John W. Freeland, Jian Zhang, Ruihua Cheng, Xiaoshan Xu, Peter Dowben 2021 University of Nebraska - Lincoln

Magnetic Field Perturbations To A Soft X-Ray-Activated Fe (Ii) Molecular Spin State Transition, Guanhua Hao, Alpha T. N’Diaye, Thilini K. Ekanayaka, Ashley S. Dale, Xuanyuan Jiang, Esha Mishra, Corbyn Mellinger, Saeed Yazdani, John W. Freeland, Jian Zhang, Ruihua Cheng, Xiaoshan Xu, Peter Dowben

Peter Dowben Publications

The X-ray-induced spin crossover transition of an Fe (II) molecular thin film in the presence and absence of a magnetic field has been investigated. The thermal activation energy barrier in the soft X-ray activation of the spin crossover transition for [Fe{H2B(pz)2 }2 (bipy)] molecular thin films is reduced in the presence of an applied magnetic field, as measured through X-ray absorption spectroscopy at various temperatures. The influence of a 1.8 T magnetic field is sufficient to cause deviations from the expected exponential spin state transition behavior which is measured in the field free case. We find …


Variational Energies For The Rydberg P States Of Helium, Cody McLeod 2021 University of Windsor

Variational Energies For The Rydberg P States Of Helium, Cody Mcleod

Electronic Theses and Dissertations

The aim of this work is to solve the quantum mechanical three-body problem for helium, and to obtain high precision eigenvalues for the higher-lying Rydberg states where previous methods have been of limited accuracy. A variational method in correlated Hylleraas coordinates is used involving three distinct distance scales, called a triple basis set. The eigenvalues and matrix elements of other operators are computed for P states of helium up to n = 15 using the varational method with a triple basis set in Hylleraas coordinates. The construction of the wave functions, as well as the behaviour of the asymptotic, intermediate …


Giant Transport Anisotropy In Res2 Revealed Via Nanoscale Conducting-Path Control, Dawei Li, Shuo Sun, Jingfeng Song, Ding-Fu Shao, Evgeny Y. Tsymbal, Stephen Ducharme, Xia Hong 2021 University of Nebraska-Lincoln

Giant Transport Anisotropy In Res2 Revealed Via Nanoscale Conducting-Path Control, Dawei Li, Shuo Sun, Jingfeng Song, Ding-Fu Shao, Evgeny Y. Tsymbal, Stephen Ducharme, Xia Hong

Stephen Ducharme Publications

The low in-plane symmetry in layered 1T’-ReS2 results in strong band anisotropy, while its manifestation in the electronic properties is challenging to resolve due to the lack of effective approaches for controlling the local current path. In this work, we reveal the giant transport anisotropy in monolayer to four-layer ReS2 by creating directional conducting paths via nanoscale ferroelectric control. By reversing the polarization of a ferroelectric polymer top layer, we induce a conductivity switching ratio of >1.5 × 108 in the ReS2 channel at 300 K. Characterizing the domain-defined conducting nanowires in an insulating background shows that the …


Spontaneous Fluctuations In A Magnetic Fe/Gd Skyrmion Lattice, M. H. Seaberg, B. Holladay, S. A. Montoya, X. Y. Zheng, J. C.T. Lee, A. H. Reid, J. D. Koralek, L. Shen, V. Esposito, G. Coslovich, P. Walter, S. Zohar, V. Thampy, M. F. Lin, P. Hart, K. Nakahara, R. Streubel, S. D. Kevan, P. Fischer, W. Colocho, A. Lutman, F. J. Decker, E. E. Fullerton, M. Dunne, S. Roy, S. K. Sinha, J. J. Turner 2021 SLAC National Accelerator Laboratory

Spontaneous Fluctuations In A Magnetic Fe/Gd Skyrmion Lattice, M. H. Seaberg, B. Holladay, S. A. Montoya, X. Y. Zheng, J. C.T. Lee, A. H. Reid, J. D. Koralek, L. Shen, V. Esposito, G. Coslovich, P. Walter, S. Zohar, V. Thampy, M. F. Lin, P. Hart, K. Nakahara, R. Streubel, S. D. Kevan, P. Fischer, W. Colocho, A. Lutman, F. J. Decker, E. E. Fullerton, M. Dunne, S. Roy, S. K. Sinha, J. J. Turner

Robert Streubel Papers

Magnetic skyrmions are topological spin textures that exhibit classical or quantum quasiparticle behavior. A substantial amount of research has occurred in this field, both because of their unique electromagnetic properties and potential application for future nonvolatile memory storage applications, as well as fundamental questions on their topology and unique magnetic phases. Here, we investigate the fluctuation properties of a magnetic Fe/Gd skyrmion lattice, using short-pulsed x rays. We first measure spontaneous fluctuations of the skyrmion lattice phase and find an inherent, collective mode showing an underdamped oscillation with a relaxation of a couple of nanoseconds. Further observations track the response …


Nonlinear Optical Studies Of Interfacial Ferroelectricity And Strain Distribution In Perovskite Dielectric Films, Tony Le 2021 The Graduate Center, City University of New York

Nonlinear Optical Studies Of Interfacial Ferroelectricity And Strain Distribution In Perovskite Dielectric Films, Tony Le

Dissertations, Theses, and Capstone Projects

Dielectric and ferroelectric perovskite films have been model energy storage structures for their low-dielectric loss, extremely high charge-discharge speed, and good temperature stability, yet there is still much to understand about the material’s limitations. This dissertation presents a detailed understanding of the strain-induced ferroelectricity at the boundary between a strontium titanate (SrTiO3) ultrathin film epitaxially grown on a germanium (Ge) substrate through optical second harmonic generation (SHG), and the polydomain distribution in the Zr-doped BaTiO3 (BZT) films by time-resolved pump-probe spectroscopy.

First, SHG measurements were performed to reveal interfacial ferroelectricity in the epitaxial SrTiO3/Ge (100) …


Development Of A Low Field Mri-Based Approach For Observation Of Water Penetration Into Clay: Preliminary Results, Shivam Gupta 2021 Western University

Development Of A Low Field Mri-Based Approach For Observation Of Water Penetration Into Clay: Preliminary Results, Shivam Gupta

Undergraduate Student Research Internships Conference

Magnetic resonance imaging (MRI) are considered one of the most efficient and non-invasive methods of observing water content in permeable substances. MRI can visualize and quantify the movement of water in real time. In this study, MRI was used to observe the water penetration through clay. Furthermore, MRI can acquire three-dimensional data due to its radio-frequency signals from any orientation. The contrast of the images produced by MRI is a display of the fluid concentration. As such, any change in the contrast intensity is interpreted as a regional change in the concentration of fluid. This report summarizes the preliminary results …


Simulating 129-Xe Hyperpolarization, Jacob F. Abiad 2021 Western University

Simulating 129-Xe Hyperpolarization, Jacob F. Abiad

Undergraduate Student Research Internships Conference

Hyperpolarized 129-Xe is an important resource in many fields of medical physics and MRI research. The physics of the efficient production of hyperpolarized 129-Xe is therefore equally worth investigation. The main process of hyperpolarizing 129-Xe is Spin Exchange Optical Pumping (SEOP) and is dependent on several physical factors that can be difficult to constantly change in a lab setting. Physical modelling of 129-Xe hyperpolarization allows for the more efficient testing of hyperpolarization physics in a wide array of experimental setups to better determine the optimal values for hyperpolarization. This research project attempted to create a working model for 129-Xe hyperpolarization …


Dicationic Stilbazolium Salts: Structural, Thermal, Optical, And Ionic Conduction Properties, Pradip K. Bhowmik, Jung J. Koh, David King, Haesook Han, Benoît Heinrich, Bertrand Donnio, Daniel Zaton, Alfonso Martinez-Felipe 2021 University of Nevada, Las Vegas

Dicationic Stilbazolium Salts: Structural, Thermal, Optical, And Ionic Conduction Properties, Pradip K. Bhowmik, Jung J. Koh, David King, Haesook Han, Benoît Heinrich, Bertrand Donnio, Daniel Zaton, Alfonso Martinez-Felipe

Chemistry and Biochemistry Faculty Publications

Two series of new dicationic stilbazolium salts containing tosylate and triflimide counterions, respectively, were synthesized and characterized by spectroscopic techniques and elemental analysis. Despite of their promesogenic structures, none of these salts are mesomorphous, and instead they solely exhibit crystalline polymorphism, as deduced from differential scanning calorimetry, polarizing optical microscopy and variable temperature X-ray measurements. These salts were also found to be highly thermally stable with decomposition temperatures occurring well above 300 °C, and up to 367 °C for the triflimide salts, as determined by thermogravimetric analysis. UV–Vis absorption and photoluminescent properties were examined in both solution and in the …


High Sensitivity Multi-Axes Rotation Sensing Using Large Momentum Transfer Point Source Atom Interferometry, Jinyang Li, Gregório R. M. da Silva, Wayne Cheng-Wei Huang, Mohamed Fouda, Jason Bonacum, Timothy L. Kovachy, Selim M. Shahriar 2021 Northwestern University

High Sensitivity Multi-Axes Rotation Sensing Using Large Momentum Transfer Point Source Atom Interferometry, Jinyang Li, Gregório R. M. Da Silva, Wayne Cheng-Wei Huang, Mohamed Fouda, Jason Bonacum, Timothy L. Kovachy, Selim M. Shahriar

Faculty Publications, Department of Physics and Astronomy

A point source interferometer (PSI) is a device where atoms are split and recombined by applying a temporal sequence of Raman pulses during the expansion of a cloud of cold atoms behaving approximately as a point source. The PSI can work as a sensitive multi-axes gyroscope that can automatically filter out the signal from accelerations. The phase shift arising from the rotations is proportional to the momentum transferred to each atom from the Raman pulses. Therefore, by increasing the momentum transfer, it should be possible to enhance the sensitivity of the PSI. Here, we investigate the degree of enhancement in …


Fabrication Of Specialized Scintillators For Nuclear Security Applications, Cordell James Delzer 2021 University of Tennessee, Knoxville

Fabrication Of Specialized Scintillators For Nuclear Security Applications, Cordell James Delzer

Doctoral Dissertations

Radiation detectors are important for a variety of fields including medical imaging, oil drilling, and nuclear security. Within nuclear security, they can serve a multitude of purposes whether that be imaging, localization, isotopic identification, or even just activity measurement. Even without directly seeing a nuclear material it is often able to notice their existence without a detector. Scintillators make up an important part of these detectors due to their large intrinsic efficiency, low cost, large volume, and relatively low upkeep. Due to the importance of the large number of purposes these scintillators may be used for, it can often be …


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