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Full-Text Articles in Physics

Phys 812 Apr 2024

Phys 812

Department of Physics and Astronomy: Syllabi

No abstract provided.


Ultrafast Electronic Relaxation Pathways Of The Molecular Photoswitch Quadricyclane, Kurtis D. Borne, Joseph C. Cooper, Michael N. R. Ashfold, Julien Bachmann, Surjendu Bhattacharyya, Rebecca Boll5, Matteo Bonanomi, Michael Bosch, Carlo Callegari, Martin Centurion, Marcello Coreno, Basile F. E. Curchod, Miltcho B. Danailov, Alexander Demidovich, Michele Di Fraia, Benjamin Erk, Davide Faccialà, Raimund Feifel, Ruaridh J. G. Forbes, Christopher S. Hansen, David M. P. Holland, Rebecca A. Ingle, Roland Lindh, Lingyu Ma, Henry G. Mcghee, Sri Bhavya Muvva, Joao Pedro Figueira Nunes, Asami Odate, Shashank Pathak, Oksana Plekan, Kevin C. Prince, Primoz Rebernik, Arnaud Rouzée, Artem Rudenko, Alberto Simoncig, Richard J. Squibb, Anbu Selvam Venkatachalam, Caterina Vozzi, Peter M. Weber, Adam Kirrander, Daniel Rolles Dec 2023

Ultrafast Electronic Relaxation Pathways Of The Molecular Photoswitch Quadricyclane, Kurtis D. Borne, Joseph C. Cooper, Michael N. R. Ashfold, Julien Bachmann, Surjendu Bhattacharyya, Rebecca Boll5, Matteo Bonanomi, Michael Bosch, Carlo Callegari, Martin Centurion, Marcello Coreno, Basile F. E. Curchod, Miltcho B. Danailov, Alexander Demidovich, Michele Di Fraia, Benjamin Erk, Davide Faccialà, Raimund Feifel, Ruaridh J. G. Forbes, Christopher S. Hansen, David M. P. Holland, Rebecca A. Ingle, Roland Lindh, Lingyu Ma, Henry G. Mcghee, Sri Bhavya Muvva, Joao Pedro Figueira Nunes, Asami Odate, Shashank Pathak, Oksana Plekan, Kevin C. Prince, Primoz Rebernik, Arnaud Rouzée, Artem Rudenko, Alberto Simoncig, Richard J. Squibb, Anbu Selvam Venkatachalam, Caterina Vozzi, Peter M. Weber, Adam Kirrander, Daniel Rolles

Martin Centurion Publications

The light-induced ultrafast switching between molecular isomers norbornadiene and quadricyclane can reversibly store and release a substantial amount of chemical energy. Prior work observed signatures of ultrafast molecular dynamics in both isomers upon ultraviolet excitation but could not follow the electronic relaxation all the way back to the ground state experimentally. Here we study the electronic relaxation of quadricyclane after exciting in the ultraviolet (201 nanometres) using time-resolved gas-phase extreme ultraviolet photoelectron spectroscopy combined with non-adiabatic molecular dynamics simulations. We identify two competing pathways by which electronically excited quadricyclane molecules relax to the electronic ground state. The fast pathway (<100 femtoseconds) is distinguished by effective coupling to valence electronic states, while the slow pathway involves initial motions across Rydberg states and takes several hundred femtoseconds. Both pathways facilitate interconversion between the two isomers, albeit on different timescales, and we predict that the branching ratio of norbornadiene/ quadricyclane products immediately after returning to the electronic ground state is approximately 3:2.


Relativistic Ultrafast Electron Diffraction At High Repetition Rates, K. M. Siddiqui, D. B. Durham, F. Cropp, F. Ji, S. Paiagua, C. Ophus, N. C. Andresen, L. Jin, J. Wu, S. Wang, X. Zhang, W. You, M. Murnane, Martin Centurion, X. Wang, D. S. Slaughter, R. A. Kaindl, P. Musumeci, A. M. Minor, D. Filippetto Dec 2023

Relativistic Ultrafast Electron Diffraction At High Repetition Rates, K. M. Siddiqui, D. B. Durham, F. Cropp, F. Ji, S. Paiagua, C. Ophus, N. C. Andresen, L. Jin, J. Wu, S. Wang, X. Zhang, W. You, M. Murnane, Martin Centurion, X. Wang, D. S. Slaughter, R. A. Kaindl, P. Musumeci, A. M. Minor, D. Filippetto

Department of Physics and Astronomy: Faculty Publications

The ability to resolve the dynamics of matter on its native temporal and spatial scales constitutes a key challenge and convergent theme across chemistry, biology, and materials science. The last couple of decades have witnessed ultrafast electron diffraction (UED) emerge as one of the forefront techniques with the sensitivity to resolve atomic motions. Increasingly sophisticated UED instruments are being developed that are aimed at increasing the beam brightness in order to observe structural signatures, but so far they have been limited to low average current beams. Here, we present the technical design and capabilities of the HiRES (High Repetition-rate Electron …


Characterization Of Interlayer Laser Shock Peening During Fused Filament Fabrication Of Polylactic Acid (Pla), Fabien Denise Dec 2023

Characterization Of Interlayer Laser Shock Peening During Fused Filament Fabrication Of Polylactic Acid (Pla), Fabien Denise

Department of Mechanical and Materials Engineering: Dissertations, Theses, and Student Research

The field of additive manufacturing (AM) has gained a significant amount of popularity due to the increasing need for more sustainable manufacturing techniques and the adaptive development of complex product geometries. The problem is that AM parts routinely exhibit flaws or weaknesses that affect functionality or performance. Over the years, surface treatments have been developed to compensate certain flaws or weaknesses in manufactured products. Combining surface treatments with the modularity of additive manufacturing could lead to more adaptable and creative improvements of product functions in the future. The current work evaluates the feasibility of pursuing a new research axis in …


Capturing The Generation And Structural Transformations Of Molecular Ions, Jun Heo, Doeyeong Kim, Alekos Segalina, Hosung Ki, Doo-Sik Ahn, Seonggon Lee, Jungmin Kim, Yongjun Cha, Kyung Won Lee, Jie Yang, J. Pedro F. Nunes, Xijie Wang, Hyotcherl Ihee Nov 2023

Capturing The Generation And Structural Transformations Of Molecular Ions, Jun Heo, Doeyeong Kim, Alekos Segalina, Hosung Ki, Doo-Sik Ahn, Seonggon Lee, Jungmin Kim, Yongjun Cha, Kyung Won Lee, Jie Yang, J. Pedro F. Nunes, Xijie Wang, Hyotcherl Ihee

Department of Physics and Astronomy: Faculty Publications

Molecular ions are ubiquitous and play pivotal roles1–3 in many reactions, particularly in the context of atmospheric and interstellar chemistry4–6. However, their structures and conformational transitions7,8, particularly in the gas phase, are less explored than those of neutral molecules owing to experimental difficulties. A case in point is the halonium ions9–11, whose highly reactive nature and ring strain make them short-lived intermediates that are readily attacked even by weak nucleophiles and thus challenging to isolate or capture before they undergo further reaction. Here we show that megaelectronvolt ultrafast electron diffraction (MeV-UED)12–14, …


Prediction Of Giant Tunneling Magnetoresistance In Ruo2/Tio2/Ruo2 (110) Antiferromagnetic Tunnel Junctions, Yuan-Yuan Jiang, Zi-An Wang, Kartik Samanta, Shu-Hui Zhang, Rui-Chun Xiao, W. J. Lu, Y. P. Sun, Evgeny Y. Tsymbal, Ding-Fu Shao Nov 2023

Prediction Of Giant Tunneling Magnetoresistance In Ruo2/Tio2/Ruo2 (110) Antiferromagnetic Tunnel Junctions, Yuan-Yuan Jiang, Zi-An Wang, Kartik Samanta, Shu-Hui Zhang, Rui-Chun Xiao, W. J. Lu, Y. P. Sun, Evgeny Y. Tsymbal, Ding-Fu Shao

Department of Physics and Astronomy: Faculty Publications

Using first-principles quantum-transport calculations, we investigate spin-dependent electronic and transport properties of antiferromagnetic tunnel junctions (AFMTJs) that consist of (110)-oriented antiferromagnetic (AFM) metal RuO2 electrodes and an insulating TiO2 tunneling barrier. We predict the emergence of a giant tunneling magnetoresistance (TMR) effect in a wide energy window, a series of barrier layer thicknesses, and different interface terminations, indicating the robustness of this effect. We show that the predicted TMR cannot be explained in terms of the global transport spin-polarization of RuO2 (110) but is well understood based on matching the momentum-dependent spin-polarized conduction channels of the two …


Relativistic Ultrafast Electron Diffraction At High Repetition Rates, K. M. Siddiqui, D. B. Durham, F. Cropp, F. Ji, S. Paiagua, C. Ophus, N. C. Andresen, L. Jin, J. Wu, S. Wang, X. Zhang, W. You, M. Murnane, Martin Centurion, X. Wang, D. S. Slaughter, R. A. Kaindl, P. Musumeci, A. M. Minor, D. Filippetto Nov 2023

Relativistic Ultrafast Electron Diffraction At High Repetition Rates, K. M. Siddiqui, D. B. Durham, F. Cropp, F. Ji, S. Paiagua, C. Ophus, N. C. Andresen, L. Jin, J. Wu, S. Wang, X. Zhang, W. You, M. Murnane, Martin Centurion, X. Wang, D. S. Slaughter, R. A. Kaindl, P. Musumeci, A. M. Minor, D. Filippetto

Martin Centurion Publications

The ability to resolve the dynamics of matter on its native temporal and spatial scales constitutes a key challenge and convergent theme across chemistry, biology, and materials science. The last couple of decades have witnessed ultrafast electron diffraction (UED) emerge as one of the forefront techniques with the sensitivity to resolve atomic motions. Increasingly sophisticated UED instruments are being developed that are aimed at increasing the beam brightness in order to observe structural signatures, but so far they have been limited to low average current beams. Here, we present the technical design and capabilities of the HiRES (High Repetition-rate Electron …


Probing The Electroweak Phase Transition With Exotic Higgs Decays, Marcela Carena, Jonathan Kozaczuk, Zhen Liu, Tong Ou, Michael J. Ramsey-Musolf, Jessie Shelton, Yikun Wang, Ke-Pan Xie Nov 2023

Probing The Electroweak Phase Transition With Exotic Higgs Decays, Marcela Carena, Jonathan Kozaczuk, Zhen Liu, Tong Ou, Michael J. Ramsey-Musolf, Jessie Shelton, Yikun Wang, Ke-Pan Xie

Department of Physics and Astronomy: Faculty Publications

An essential goal of the Higgs physics program at the LHC and beyond is to explore the nature of the Higgs potential and shed light on the mechanism of electroweak symmetry breaking. An important class of models alter the thermal history of electroweak symmetry breaking from the predictions of the Standard Model (SM). This paper reviews the existence of a region of parameter space where a strong first-order electroweak phase transition is compatible with exotic decays of the SM-like Higgs boson. A dedicated search for exotic Higgs decays can actively explore this framework at the Large Hadron Collider (LHC), while …


Hydroxyapatite-Based Coatings On Silicon Wafers And Printed Zirconia, Antoine Chauvin Nov 2023

Hydroxyapatite-Based Coatings On Silicon Wafers And Printed Zirconia, Antoine Chauvin

Department of Mechanical and Materials Engineering: Dissertations, Theses, and Student Research

Dental surgery needs a naturally attract implant design that can ensure both osseointegration and soft tissue integration. Hydroxyapatite (HAp), the main mineral constituent of dentine and tooth enamel, is commonly used as a coating component, notably for overlaying titanium– or ceramics–based implants. This thesis aims to investigate the behavior of a HAp-based coating, specifically designed to be compatible with a porous substrate. Coating layers are made by sol–gel dip coating by immersion of porous substrates made by additive manufacturing into solutions of HAp, having been mixed with polyethyleneimine (PEI), to improve the adhesion of HAp on the substrate. First, the …


Uv Dynamics Of Different Ring Molecules Studied By Ultrafast Electron Diffraction, Sajib Kumar Saha Nov 2023

Uv Dynamics Of Different Ring Molecules Studied By Ultrafast Electron Diffraction, Sajib Kumar Saha

Dissertations and Doctoral Documents, University of Nebraska-Lincoln, 2023–

Understanding natural light-induced phenomena requires a direct viewing of atomic motion during structural evolution, which, in turn, facilitates controlling and manipulating these light-induced processes. Ultrafast Electron Diffraction (UED) is a structure-sensitive technique that can probe electronic and nuclear dynamics at sub-angstrom spatial and femtosecond time scales. UED has become a vital tool for studying photo-induced molecular dynamics and underlying science. Organic ring systems are prevalent in biology, materials, and pharmaceuticals. Their synthesis and transformation are fundamental in synthetic chemistry, influencing various fields. We used UV photons to photo-excite different cyclic molecules and investigated their photo-dynamics using gas phase UED. The …


A Simple, Isotropic Depolarized Light Source, Keith Foreman, T. J. Gay Oct 2023

A Simple, Isotropic Depolarized Light Source, Keith Foreman, T. J. Gay

Department of Physics and Astronomy: Faculty Publications

Unpolarized light can be an important tool in optical experiments. Producing it, however, can prove to be a challenge. Natural sources of light that are commonly thought of as unpolarized are, in fact, either weakly polarized or not practical sources of light in a laboratory setting. Standard, commercially available light depolarizers produce unpolarized light only after the polarization state of the light across the diameter of the output beam has been averaged. Locally, such beams are highly polarized. In this work, we report a simple, low cost light depolarizer capable of producing light with a total polarization of less than …


Breakdown Of The Drift-Diffusion Model For Transverse Spin Transport In A Disordered Pt Film, Kirill D. Belashchenko, Giovanni G. Baez Flores, Wuzhang Fang, Alexey Kovalev, Mark Van Schilfgaarde, Paul M. Haney, Mark D. Stiles Oct 2023

Breakdown Of The Drift-Diffusion Model For Transverse Spin Transport In A Disordered Pt Film, Kirill D. Belashchenko, Giovanni G. Baez Flores, Wuzhang Fang, Alexey Kovalev, Mark Van Schilfgaarde, Paul M. Haney, Mark D. Stiles

Department of Physics and Astronomy: Faculty Publications

Spin-accumulation and spin-current profiles are calculated for a disordered Pt film subjected to an in-plane electric current within the nonequilibrium Green's function approach. In the bulklike region of the sample, this approach captures the intrinsic spin Hall effect found in other calculations. Near the surfaces, the results reveal qualitative differences with the results of the widely used spin-diffusion model, even when the boundary conditions are modified to try to account for them. One difference is that the effective spin-diffusion length for transverse spin transport is significantly different from its longitudinal counterpart and is instead similar to the mean-free path. This …


Majorana Bound States In A D-Wave Superconductor Planar Josephson Junction, Hamed Vakili, Moaz Ali, Mohamed Elekhtiar, Alexey Kovalev Oct 2023

Majorana Bound States In A D-Wave Superconductor Planar Josephson Junction, Hamed Vakili, Moaz Ali, Mohamed Elekhtiar, Alexey Kovalev

Department of Physics and Astronomy: Faculty Publications

We study phase-controlled planar Josephson junctions comprising a two-dimensional electron gas with strong spin-orbit coupling and d-wave superconductors, which have an advantage of a high critical temperature. We show that a region between the two superconductors can be tuned into a topological state by the in-plane Zeeman field, and can host Majorana bound states. The phase diagram as a function of the Zeeman field, chemical potential, and the phase difference between superconductors exhibits the appearance of Majorana bound states for a wide range of parameters. We further investigate the behavior of the topological gap and its dependence on the …


Observation Of Τ Lepton Pair Production In Ultraperipheral Pb-Pb Collisions At √SNn=5.02 Tev, A. Tumasyan Oct 2023

Observation Of Τ Lepton Pair Production In Ultraperipheral Pb-Pb Collisions At √SNn=5.02 Tev, A. Tumasyan

Department of Physics and Astronomy: Faculty Publications

We present an observation of photon-photon production of τ lepton pairs in ultraperipheral lead-lead collisions. The measurement is based on a data sample with an integrated luminosity of 404 μb−1 collected by the CMS experiment at a center-of-mass energy per nucleon pair of √sNN = 5.02 TeV. The γγ → τ+τ process is observed for τ+τ events with a muon and three charged hadrons in the final state. The measured fiducial cross section is σ(γγ → τ+τ-) = 4.8 ± 0.6(stat) ± 0.5(syst) μb, where the second …


Scaling Isolated-Attosecond-Pulse Duration By Controlling A Trajectory Parameter, Dian Peng, Jean Marcel Ngoko Djiokap Oct 2023

Scaling Isolated-Attosecond-Pulse Duration By Controlling A Trajectory Parameter, Dian Peng, Jean Marcel Ngoko Djiokap

Department of Physics and Astronomy: Faculty Publications

Reaching an ever shorter duration of isolated attosecond pulses (IAPs) is an ongoing mission in attosecond science. Wide usage of long-wavelength driving lasers has greatly broadened bandwidths for generating IAPs. We propose a strategy to further exploit the ability of a long-wavelength laser in producing short IAPs. We introduce a scaling relationship between IAP duration and a trajectory parameter that is associated with the classical cutoff trajectory of high-order harmonic generation (HHG) in gases. This trajectory parameter can facilitate in shortening IAP duration by shaping laser waveform. We demonstrate the effectiveness of our methods with calculations of HHG from Ne …


Electrode Effect On Ferroelectricity In Free-Standing Membranes Of Pbzr0.2Ti0.8O3, Qiuchen Wu, Kun Wang, Alyssa Simpson, Yifei Hao, Jia Wang, Dawei Li, Xia Hong Oct 2023

Electrode Effect On Ferroelectricity In Free-Standing Membranes Of Pbzr0.2Ti0.8O3, Qiuchen Wu, Kun Wang, Alyssa Simpson, Yifei Hao, Jia Wang, Dawei Li, Xia Hong

Department of Physics and Astronomy: Faculty Publications

We report the effects of screening capacity, surface roughness, and interfacial epitaxy of the bottom electrodes on the polarization switching, domain wall (DW) roughness, and ferroelectric Curie temperature (TC) of PbZr0.2Ti0.8O3 (PZT)- based free-standing membranes. Singe crystalline 10−50 nm (001) PZT and PZT/La0.67Sr0.33MnO3 (LSMO) membranes are prepared on Au, correlated oxide LSMO, and two-dimensional (2D) semiconductor MoS2 base layers. Switching the polarization of PZT yields nonvolatile current modulation in the MoS2 channel at room temperature, with an on/off ratio of up to 2 × 105 …


Phys 431/831 Oct 2023

Phys 431/831

Department of Physics and Astronomy: Syllabi

No abstract provided.


Phys 811 Oct 2023

Phys 811

Department of Physics and Astronomy: Syllabi

No abstract provided.


Astr 103 Oct 2023

Astr 103

Department of Physics and Astronomy: Syllabi

No abstract provided.


Astr 204 Oct 2023

Astr 204

Department of Physics and Astronomy: Syllabi

No abstract provided.


Phys 311 Oct 2023

Phys 311

Department of Physics and Astronomy: Syllabi

No abstract provided.


Phys 911 Oct 2023

Phys 911

Department of Physics and Astronomy: Syllabi

No abstract provided.


Phys 925 Oct 2023

Phys 925

Department of Physics and Astronomy: Syllabi

No abstract provided.


Phys 201 Oct 2023

Phys 201

Department of Physics and Astronomy: Syllabi

No abstract provided.


Phys 441/841 Oct 2023

Phys 441/841

Department of Physics and Astronomy: Syllabi

No abstract provided.


Astr 224 Oct 2023

Astr 224

Department of Physics and Astronomy: Syllabi

No abstract provided.


Astr 103h Oct 2023

Astr 103h

Department of Physics and Astronomy: Syllabi

No abstract provided.


Astr 117 Oct 2023

Astr 117

Department of Physics and Astronomy: Syllabi

No abstract provided.


Phys 151 Oct 2023

Phys 151

Department of Physics and Astronomy: Syllabi

No abstract provided.


Phys 452/852 Oct 2023

Phys 452/852

Department of Physics and Astronomy: Syllabi

No abstract provided.