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- And slower but still dynamic changes occur in YAP nuclear translocation in response to time-dependent application of a magnetic field. The near instantaneous change in hydrogel mechanics provides new insight into the effect of changing extracellular stiffness on both acute and chronic changes in diverse cell types embedded in protein-based scaffolds. Due to its flexibility (1)
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Articles 1 - 30 of 153
Full-Text Articles in Physics
Second-Harmonic Signature Of Chiral Spin Structures In W/Pt/Co Heterostructures With Tunable Magnetic Anisotropy, Yang Wang, Ying-Ting Chan, Xiao Wang, Tao Wang, Xuemei Cheng, Weida Wu, John Q. Xiao
Second-Harmonic Signature Of Chiral Spin Structures In W/Pt/Co Heterostructures With Tunable Magnetic Anisotropy, Yang Wang, Ying-Ting Chan, Xiao Wang, Tao Wang, Xuemei Cheng, Weida Wu, John Q. Xiao
Physics Faculty Research and Scholarship
Second-harmonic Hall voltage (SHV) measurement method has been widely used to characterize the strengths of spin–orbit torques (SOTs) in heavy metal/ferromagnet thin films saturated in the single-domain regime. Here, we show that the magnetic anisotropy of a W/Pt/Co trilayer can be robustly tuned from in-plane to out-of-plane by varying W, Pt, or Co thicknesses. Moreover, in samples with easy-cone anisotropy, SHV measurements exhibit anomalous ‘humps’ in the multidomain regime accessed by applying a nearly out-of-plane external magnetic field. These hump features can only be explained as a result of the formation of Néel-type domain walls, efficiently driven by nevertheless small …
Interfacial And Surface Magnetism In Epitaxial Nico2o4(001)/Mgal2o4 Films, Corbyn Mellinger, Xiao Wang, Arjun Subedi, Andy T. Clark, Takashi Komesu, Richard Rosenberg, Peter A. Dowben, Xuemei Cheng, Xiaoshan Xu
Interfacial And Surface Magnetism In Epitaxial Nico2o4(001)/Mgal2o4 Films, Corbyn Mellinger, Xiao Wang, Arjun Subedi, Andy T. Clark, Takashi Komesu, Richard Rosenberg, Peter A. Dowben, Xuemei Cheng, Xiaoshan Xu
Physics Faculty Research and Scholarship
NiCo2O4 (NCO) films grown on MgAl2O4 (001) substrates have been studied using magnetometry, x-ray magnetic circular dichroism (XMCD) based on x-ray absorption spectroscopy, and spin-polarized inverse photoemission spectroscopy (SPIPES) with various thickness down to 1.6 nm. The magnetic behavior can be understood in terms of a layer of optimal NCO and an interfacial layer (1.2± 0.1 nm), with a small canting of magnetization at the surface. The thickness dependence of the optimal layer can be described by the finite-scaling theory with a critical exponent consistent with the high perpendicular magnetic anisotropy. The interfacial layer couples antiferromagnetically to the optimal layer, …
Dative Epitaxy Of Commensurate Monocrystalline Covalent Van Der Waals Moiré Supercrystal, Mengying Bian, Liang Zhu, Xiao Wang, Junho Choi, Rajesh V. Chopdekar, Sichen Wei, Lishu Wu, Chang Huai, Austin Marga, Qishuo Yang, Yuguang C. Li, Fei Yao, Ting Yu, Scott A. Crooker National High Magnetic Field Laboratory, Los Alamos National Laboratory, Xuemei Cheng, Renat F. Sabirianov, Shengbai Zhang, Junhao Lin, Yanglong Hou, Hao Zeng
Dative Epitaxy Of Commensurate Monocrystalline Covalent Van Der Waals Moiré Supercrystal, Mengying Bian, Liang Zhu, Xiao Wang, Junho Choi, Rajesh V. Chopdekar, Sichen Wei, Lishu Wu, Chang Huai, Austin Marga, Qishuo Yang, Yuguang C. Li, Fei Yao, Ting Yu, Scott A. Crooker National High Magnetic Field Laboratory, Los Alamos National Laboratory, Xuemei Cheng, Renat F. Sabirianov, Shengbai Zhang, Junhao Lin, Yanglong Hou, Hao Zeng
Physics Faculty Research and Scholarship
Realizing van der Waals (vdW) epitaxy in the 1980s represents a breakthrough that circumvents the stringent lattice matching and processing compatibility requirements in conventional covalent heteroepitaxy. However, due to the weak vdW interactions, there is little control over film qualities by the substrate. Typically, discrete domains with a spread of misorientation angles are formed, limiting the applicability of vdW epitaxy. Here, the epitaxial growth of monocrystalline, covalent Cr5Te8 2D crystals on monolayer vdW WSe2 by chemical vapor deposition is reported, driven by interfacial dative bond formation. The lattice of Cr5Te8, with a lateral dimension of a few tens of micrometers, …
Impact Of The Electron Density And Temperature Gradient On Drift-Wave Turbulence In The Large Plasma Device, Conor Perks, Saskia Mordijck, Troy Carter, Bart Van Compernolle, Stephen Vincena, Giovanni Rossi, David A. Schaffner
Impact Of The Electron Density And Temperature Gradient On Drift-Wave Turbulence In The Large Plasma Device, Conor Perks, Saskia Mordijck, Troy Carter, Bart Van Compernolle, Stephen Vincena, Giovanni Rossi, David A. Schaffner
Physics Faculty Research and Scholarship
In this paper we present an experimental study of edge turbulence in the Large Plasma Device at UCLA. We utilize a scan of discharge power and prefill pressure (neutral density) to show experimentally that turbulent density fluctuations decrease with decreasing density gradient, as predicted for resistive drift-wave turbulence (RDWT). As expected for RDWT, we observe that the cross-phase between the density and potential fluctuations is close to 0. Moreover, the addition of an electron temperature gradient leads to a reduction in the amplitude of the density fluctuations, as expected for RDWT. However, counter to theoretical expectations, we find that the …
The Effect Of Polymer Stiffness On Magnetization Reversal Of Magnetorheological Elastomers, Andy T. Clark, David Marchfield, Zheng Cao, Tong Dang, Nan Tang, Dustin Gilbert, Elise A. Corbin, Kristen S. Buchanan, Xuemei Cheng
The Effect Of Polymer Stiffness On Magnetization Reversal Of Magnetorheological Elastomers, Andy T. Clark, David Marchfield, Zheng Cao, Tong Dang, Nan Tang, Dustin Gilbert, Elise A. Corbin, Kristen S. Buchanan, Xuemei Cheng
Physics Faculty Research and Scholarship
Ultrasoft magnetorheological elastomers (MREs) offer convenient real-time magnetic field control of mechanical properties that provides a means to mimic mechanical cues and regulators of cells in vitro. Here, we systematically investigate the effect of polymer stiffness on magnetization reversal of MREs using a combination of magnetometry measurements and computational modeling. Poly-dimethylsiloxane- based MREs with Young’s moduli that range over two orders of magnitude were synthesized using commercial polymers SylgardTM 527, Sylgard 184, and carbonyl iron powder. The magnetic hysteresis loops of the softer MREs exhibit a characteristic pinched loop shape with almost zero remanence and loop widening at intermediate fields …
Persistent Opto-Ferroelectric Responses In Molecular Ferroelectrics, Xuanyuan Jiang, Xiao Wang, Pratyush Buragohain, Andy T. Clark, Haidong Lu, Shashi Poddar, Le Yu, Anthony D. Dichiara, Alexei Gruverman, Xuemei Cheng, Xiaoshan Xu
Persistent Opto-Ferroelectric Responses In Molecular Ferroelectrics, Xuanyuan Jiang, Xiao Wang, Pratyush Buragohain, Andy T. Clark, Haidong Lu, Shashi Poddar, Le Yu, Anthony D. Dichiara, Alexei Gruverman, Xuemei Cheng, Xiaoshan Xu
Physics Faculty Research and Scholarship
Persistent photoresponses require optical excitations to metastable states, which are rare of ionic origin due to the indirect photon-ion interaction. In this work, we explore the photoinduced metastable proton states in the proton-transfer type molecular ferroelectric croconic acid. We observe that, after the photoexcitation, the changes of structural and ferroelectric properties relax in ∼10^3s, indicating persistent photoresponses of ionic origin. In contrast, the photoconductivity relaxes within 1 s. The 10^3s timescale suggests that the ionic metastable states result from proton transfer both along and out of the hydrogen bonds. This discovery unveils an ionic mechanism for the phototunability, which offers …
Topological Spin Memory Of Antiferromagnetically Coupled Skyrmion Pairs In Co/Gd/Pt Multilayers, Xiao Wang, Alexandra R. Stuart, Mitchell S. Swyt, Carla M. Quispe Flores, Andy T. Clark, Adzo Fiagbenu, Rajesh V. Chopdekar, Pavel N. Lapa, Zhuyun Xiao, Dava Keavney, Richard Rosenberg, Michael Vogel, John E. Pearson, Suzanne G. E. Te Velthius, Axel Hoffmann, Kristen S. Buchanan, Xuemei Cheng
Topological Spin Memory Of Antiferromagnetically Coupled Skyrmion Pairs In Co/Gd/Pt Multilayers, Xiao Wang, Alexandra R. Stuart, Mitchell S. Swyt, Carla M. Quispe Flores, Andy T. Clark, Adzo Fiagbenu, Rajesh V. Chopdekar, Pavel N. Lapa, Zhuyun Xiao, Dava Keavney, Richard Rosenberg, Michael Vogel, John E. Pearson, Suzanne G. E. Te Velthius, Axel Hoffmann, Kristen S. Buchanan, Xuemei Cheng
Physics Faculty Research and Scholarship
Antiferromagnetically (AFM) coupled skyrmions offer potential advantages for spintronic devices, including reduced dipolar fields that may enable smaller skyrmion sizes and a reduction of the skyrmion Hall effect. However, the topological stability of AFM-coupled skyrmions subjected to dramatic spin deformation through low-temperature cycling has not been investigated. Here we report the discovery of a topological spin memory effect for AFM-coupled skyrmion pairs in [Co/Gd/Pt]10 multilayered films. Photoemission electron microscopy imaging shows that bubble skyrmions in the multilayer that are stable at room temperature evolve into complex in-plane spin textures as the temperature is lowered and reform completely when the sample …
Measurement Of The Taylor Scale In A Magnetized Turbulent Laboratory Plasma Wind-Tunnel, Carlos A. Cartagena-Sanchez, Joshua M. Carlson, David A. Schaffner
Measurement Of The Taylor Scale In A Magnetized Turbulent Laboratory Plasma Wind-Tunnel, Carlos A. Cartagena-Sanchez, Joshua M. Carlson, David A. Schaffner
Physics Faculty Research and Scholarship
The fluid Taylor scale is measured in the Bryn Mawr Experiment (BMX) of the Bryn Mawr Plasma Laboratory and examined as a potential dissipation scale of magnetic turbulence within the plasma. We present the first laboratory measurements of the Taylor scale of a turbulent magnetized plasma through multi-point correlations of broadband magnetic fluctuations. From spatial and temporal correlations, respectively, the measured Taylor scales are 261 and 361 cm. These measurements are on the same order of magnitude as estimated ion dissipation scales within the BMX plasma with ion inertial scales between 1 and 10 cm and ion gyroscales between 0:1 …
Probing Exchange Bias At The Surface Of A Doped Ferrimagnetic Insulator, Yang Wang, Xiao Wang, Andy T. Clark, Hang Chen, Xuemei Cheng, John W. Freeland, John Q. Xiao
Probing Exchange Bias At The Surface Of A Doped Ferrimagnetic Insulator, Yang Wang, Xiao Wang, Andy T. Clark, Hang Chen, Xuemei Cheng, John W. Freeland, John Q. Xiao
Physics Faculty Research and Scholarship
With the realization of stress-induced perpendicular magnetic anisotropy, efficient spin-orbit torque switching, and room temperature topological Hall effect, interest in rare earth iron garnets has been revived in recent years for their potential in spintronic applications. In this study, we investigate the magnetic properties of micrometer-thick Bi and Ga substituted thulium iron garnets (BiGa:TmIG) grown by the liquid-phase epitaxy method. Above the magnetization compensation (MC) temperature, anomalous triple hysteresis is observed in BiGa:TmIG/Pt heterostructures by anomalous Hall effect measurements. X-ray magnetic circular dichroism and energy dispersive spectroscopy measurements reveal its origin as an internal exchange bias (EB) effect arising from …
Yyy Dynamic Tuning Of Viscoelastic Hydrogels With Carbonyl Iron Microparticles Reveals The Rapid Response Of Cells To Three-Dimensional Substrate Mechanics, Kiet A. Tran, Emile Kraus, Andy T. Clark, Alex Bennet, Katarzyna Pogoda, Xuemei Cheng, Andrejs Cēbers, Paul A. Janmey, Peter A. Galie
Yyy Dynamic Tuning Of Viscoelastic Hydrogels With Carbonyl Iron Microparticles Reveals The Rapid Response Of Cells To Three-Dimensional Substrate Mechanics, Kiet A. Tran, Emile Kraus, Andy T. Clark, Alex Bennet, Katarzyna Pogoda, Xuemei Cheng, Andrejs Cēbers, Paul A. Janmey, Peter A. Galie
Physics Faculty Research and Scholarship
Current methods to dynamically tune three-dimensional hydrogel mechanics require specific chemistries and substrates that make modest, slow, and often irreversible changes in their mechanical properties, exclude the use of protein-based scaffolds, or alter the hydrogel microstructure and pore size. Here, we rapidly and reversibly alter the mechanical properties of hydrogels consisting of extracellular matrix proteins and proteoglycans by adding carbonyl iron microparticles (MPs) and applying external magnetic fields. This approach drastically alters hydrogel mechanics: rheology reveals that application of a 4000 Oe magnetic field to a 5 mg/mL collagen hydrogel containing 10 wt % MPs increases the storage modulus from …
Magneto-Driven Gradients Of Diamagnetic Objects For Engineering Complex Tissues, Hannah M. Zlotnick, Andy T. Clark, Sarah E. Gullbrand, James L. Carey, Xuemei Cheng, Robert L. Mauck
Magneto-Driven Gradients Of Diamagnetic Objects For Engineering Complex Tissues, Hannah M. Zlotnick, Andy T. Clark, Sarah E. Gullbrand, James L. Carey, Xuemei Cheng, Robert L. Mauck
Physics Faculty Research and Scholarship
Engineering complex tissues represents an extraordinary challenge and, to date, there have been few strategies developed that can easily recapitulate native‐like cell and biofactor gradients in 3D materials. This is true despite the fact that mimicry of these gradients may be essential for the functionality of engineered graft tissues. Here, a non‐traditional magnetics‐based approach is developed to predictably position naturally diamagnetic objects in 3D hydrogels. Rather than magnetizing the objects within the hydrogel, the magnetic susceptibility of the surrounding hydrogel precursor solution is enhanced. In this way, a range of diamagnetic objects (e.g., polystyrene beads, drug delivery microcapsules, and living …
Solid State Proton Spin-Lattice Relaxation In Polycrystalline Methylphenanthrenes. Iv. 1,4-Dimethylphenanthrene, Peter A. Beckmann
Solid State Proton Spin-Lattice Relaxation In Polycrystalline Methylphenanthrenes. Iv. 1,4-Dimethylphenanthrene, Peter A. Beckmann
Physics Faculty Research and Scholarship
We present and model the NMR frequency (8.50, 22.5, and 53.0 MHz) and temperature (97–300 K) dependence of the solid state 1H spin-lattice relaxation process in polycrystalline 1,4-dimethylphenanthrene. The solid state gives rise to a situation where methyl group rotation is the only motion on the NMR time scale and the relaxation rates due to the rotations of the 1- and 4-methyl groups are conveniently well-separated in temperature. At these low NMR frequencies, both the slow- and fast-motion limits are observed for the rotation of both methyl groups which allows for a more stringent test of the models. The relaxation …
Diaryl Hydroxylamines As Pan Or Dual Inhibitors Of Indoleamine 2,3-Dioxygenase-1, Indoleamine 2,3-Dioxygenase-2 And Tryptophan Dioxygenase, Maria Winters, James B. Duhadaway, Khoa N. Pham, Ariel Lewis-Ballester, Shorouk Badir, Jenny Wai, Eesha Sheikh, Syun-Ru Yeh, George C. Pendergast, Alexander J. Muller, William Paul Malachowski
Diaryl Hydroxylamines As Pan Or Dual Inhibitors Of Indoleamine 2,3-Dioxygenase-1, Indoleamine 2,3-Dioxygenase-2 And Tryptophan Dioxygenase, Maria Winters, James B. Duhadaway, Khoa N. Pham, Ariel Lewis-Ballester, Shorouk Badir, Jenny Wai, Eesha Sheikh, Syun-Ru Yeh, George C. Pendergast, Alexander J. Muller, William Paul Malachowski
Physics Faculty Research and Scholarship
Tryptophan (Trp) catabolizing enzymes play an important and complex role in the development of cancer. Significant evidence implicates them in a range of inflammatory and immunosuppressive activities. Whereas inhibitors of indoleamine 2,3-dioxygenase-1 (IDO1) have been reported and analyzed in the clinic, fewer inhibitors have been described for tryptophan dioxygenase (TDO) and indoleamine 2,3-dioxygenase-2 (IDO2) which also have been implicated more recently in cancer, inflammation and immune control. Consequently the development of dual or pan inhibitors of these Trp catabolizing enzymes may represent a therapeutically important area of research. This is the first report to describe the development of dual and …
Measuring The Equations Of State In A Relaxed Magnetohydrodynamic Plasma, M. Kaur, L. J. Barbano, E. M. Suen-Lewis, J. E. Shrock, A. D. Light, M. R. Brown, David A. Schaffner
Measuring The Equations Of State In A Relaxed Magnetohydrodynamic Plasma, M. Kaur, L. J. Barbano, E. M. Suen-Lewis, J. E. Shrock, A. D. Light, M. R. Brown, David A. Schaffner
Physics Faculty Research and Scholarship
We report measurements of the equations of state of a fully relaxed magnetohydrodynamic (MHD) laboratory plasma. Parcels of magnetized plasma, called Taylor states, are formed in a coaxial magnetized plasma gun, and are allowed to relax and drift into a closed flux conserving volume. Density, ion temperature, and magnetic field are measured as a function of time as the Taylor states compress and heat. The theoretically predicted MHD and double adiabatic equations of state are compared to experimental measurements. We find that the MHD equation of state is inconsistent with our data.
Constraints On Radial Migration In Spiral Galaxies - Ii. Angular Momentum Distribution And Preferential Migration, Kathryne J. Daniel, Rosemary F. G. Wyse
Constraints On Radial Migration In Spiral Galaxies - Ii. Angular Momentum Distribution And Preferential Migration, Kathryne J. Daniel, Rosemary F. G. Wyse
Physics Faculty Research and Scholarship
The orbital angular momentum of individual stars in galactic discs can be permanently changed through torques from transient spiral patterns. Interactions at the corotation resonance dominate these changes and have the further property of conserving orbital circularity. We derived in an earlier paper an analytic criterion that an unperturbed stellar orbit must satisfy in order for such an interaction to occur i.e. for it to be in a trapped orbit around corotation. We here use this criterion in an investigation of how the efficiency of induced radial migration for a population of disc stars varies with the angular momentum distribution …
Constraints On Radial Migration In Spiral Galaxies – Ii. Angular Momentum Distribution And Preferential Migration, Kathryne J. Daniel, Rosemary F. G. Wyse
Constraints On Radial Migration In Spiral Galaxies – Ii. Angular Momentum Distribution And Preferential Migration, Kathryne J. Daniel, Rosemary F. G. Wyse
Physics Faculty Research and Scholarship
The orbital angular momentum of individual stars in galactic discs can be permanently changed through torques from transient spiral patterns. Interactions at the corotation resonance dominate these changes and have the further property of conserving orbital circularity. We derived in an earlier paper an analytic criterion that an unperturbed stellar orbit must satisfy in order for such an interaction to occur, i.e. for it to be in a trapped orbit around corotation. We here use this criterion in an investigation of how the efficiency of induced radial migration for a population of disc stars varies with the angular momentum distribution …
Note: Methyl And T-Butyl Group Rotation In Van Der Waals Solids, Peter A. Beckmann, Arnold L. Rheingold, Jason Schmink
Note: Methyl And T-Butyl Group Rotation In Van Der Waals Solids, Peter A. Beckmann, Arnold L. Rheingold, Jason Schmink
Physics Faculty Research and Scholarship
No abstract provided.
Tuning The Néel Temperature Of Hexagonal Ferrites By Structural Distortion, Kishan Sinha, Haohan Wang, Xiao Wang, Liying Zhou, Yuewei Yin, Wenbin Wang, Xuemei Cheng, David J. Keavney, Huibo Cao, Yaohua Liu, Xifan Wu, Xiaoshan Xu
Tuning The Néel Temperature Of Hexagonal Ferrites By Structural Distortion, Kishan Sinha, Haohan Wang, Xiao Wang, Liying Zhou, Yuewei Yin, Wenbin Wang, Xuemei Cheng, David J. Keavney, Huibo Cao, Yaohua Liu, Xifan Wu, Xiaoshan Xu
Physics Faculty Research and Scholarship
To tune the magnetic properties of hexagonal ferrites, a family of magnetoelectric multiferroic materials, by atomic-scale structural engineering, we studied the effect of structural distortion on the magnetic ordering temperature (TN) in these materials. Using the symmetry analysis, we show that unlike most antiferromagnetic rare-earth transition-metal perovskites, a larger structural distortion leads to a higher TN in hexagonal ferrites and manganites, because the K3 structural distortion induces the three-dimensional magnetic ordering, which is forbidden in the undistorted structure by symmetry. We also revealed a near-linear relation between TN and the tolerance factor and a power-law relation between TN and the …
Proton Spin-Lattice Relaxation In Organic Molecular Solids: Polymorphism And The Dependence On Sample Preparation, Peter A. Beckmann, Jamie Ford, William Paul Malachowski, Andrew R. Mcghie, Curtis E. Moore, Arnold L. Rheingold, Gilbert J. Sloan, Steven T. Szewczyk
Proton Spin-Lattice Relaxation In Organic Molecular Solids: Polymorphism And The Dependence On Sample Preparation, Peter A. Beckmann, Jamie Ford, William Paul Malachowski, Andrew R. Mcghie, Curtis E. Moore, Arnold L. Rheingold, Gilbert J. Sloan, Steven T. Szewczyk
Physics Faculty Research and Scholarship
We report solid‐state nuclear magnetic resonance 1H spin‐lattice relaxation, single‐crystal X‐ray diffraction, powder X‐ray diffraction, field emission scanning electron microscopy, and differential scanning calorimetry in solid samples of 2‐ethylanthracene (EA) and 2‐ethylanthraquinone (EAQ) that have been physically purified in different ways from the same commercial starting compounds. The solid‐state 1H spin‐lattice relaxation is always non‐exponential at high temperatures as expected when CH3 rotation is responsible for the relaxation. The 1H spin‐lattice relaxation experiments are very sensitive to the “several‐molecule” (clusters) structure of these van der Waals molecular solids. In the three differently prepared samples of EAQ, the relaxation also becomes …
Photoelectron Angular Distributions From Rotationally Resolved Autoionizing States Of N2, Alexander M. Chartrand, Elizabeth F. Mccormack, Ugo Jacovella, David M P Holland, Berenger Gans, Xiaofeng Tang, Gustavo A. García, Laurent Nahon, Stephen T. Pratt
Photoelectron Angular Distributions From Rotationally Resolved Autoionizing States Of N2, Alexander M. Chartrand, Elizabeth F. Mccormack, Ugo Jacovella, David M P Holland, Berenger Gans, Xiaofeng Tang, Gustavo A. García, Laurent Nahon, Stephen T. Pratt
Physics Faculty Research and Scholarship
The single-photon, photoelectron-photoion coincidence spectrum of N2 has been recorded at high (~1.5 cm–1 ) resolution in the region between the N2+ X 2Σg+, v+ = 0 and 1 ionization thresholds by using a double-imaging spectrometer and intense vacuum-ultraviolet light from the Synchrotron SOLEIL. This approach provides the relative photoionization cross section, the photoelectron energy distribution, and the photoelectron angular distribution as a function of photon energy. The region of interest contains autoionizing valence states, vibrationally autoionizing Rydberg states converging to vibrationally excited levels of the N2+ X 2 …
Continuity Of Heavy Rydberg Behaviour In The Ungerade Ion-Pair States Of H2, Alexander M. Chartrand, Robert J. Donovan, Kenneth P. Lawley, Elizabeth Mccormack
Continuity Of Heavy Rydberg Behaviour In The Ungerade Ion-Pair States Of H2, Alexander M. Chartrand, Robert J. Donovan, Kenneth P. Lawley, Elizabeth Mccormack
Physics Faculty Research and Scholarship
Heavy Rydberg behaviour and absolute quantum defects are reported for resonances in the ungerade manifold of H2 above the (1s, 3l) dissociation limit. The continuity of the vibrational progression of the B''B-bar state through the crossing with the 3p asymptote is demonstrated and a predominantly diabatic picture of the vibrational motion emerges, indicating that the ion-pair resonances possess little 61Σu+ state character.
Solid Solid Phase Transitions And Tert-Butyl And Methyl Group Rotation In An Organic Solid: X-Ray Diffractometry, Differential Scanning Calorimetry, And Solid-State H-1 Nuclear Spin Relaxation, Peter A. Beckmann, Andrew R. Mcghie, Arnold L. Rheingold, Gilbert J. Sloan, Steven T. Szewczyk
Solid Solid Phase Transitions And Tert-Butyl And Methyl Group Rotation In An Organic Solid: X-Ray Diffractometry, Differential Scanning Calorimetry, And Solid-State H-1 Nuclear Spin Relaxation, Peter A. Beckmann, Andrew R. Mcghie, Arnold L. Rheingold, Gilbert J. Sloan, Steven T. Szewczyk
Physics Faculty Research and Scholarship
Using solid state 1H nuclear magnetic resonance (NMR) spin-lattice relaxation experiments, we have investigated the effects of several solid-solid phase transitions on t-butyl group and methyl group rotation in solid 1,3,5-tri-t-butylbenzene. The goal is to relate the dynamics of the t-butyl groups and their constituent methyl groups to properties of the solid determined using single-crystal X-ray diffraction and differential scanning calorimetry (DSC). On cooling, the DSC experiments see a first-order, solid-solid phase transition at either 268 K or 155 K (but not both) depending on thermal history. The 155 K transition (on cooling) is identified by …
Monitoring A Simple Hydrolysis Process In An Organic Solid By Observing Methyl Group Rotation, Peter A. Beckmann, Joseph M. Bohen, Jamie Ford, William P. Malachowski, Clelia W. Mallory, Frank B. Mallory, Andrew R. Mcghie, Arnold L. Rheingold, Gilbert J. Sloan, Steven T. Szewczyk, Xianlong Wang, Kraig A. Wheeler
Monitoring A Simple Hydrolysis Process In An Organic Solid By Observing Methyl Group Rotation, Peter A. Beckmann, Joseph M. Bohen, Jamie Ford, William P. Malachowski, Clelia W. Mallory, Frank B. Mallory, Andrew R. Mcghie, Arnold L. Rheingold, Gilbert J. Sloan, Steven T. Szewczyk, Xianlong Wang, Kraig A. Wheeler
Physics Faculty Research and Scholarship
We report a variety of experiments and calculations and their interpretations regarding methyl group (CH3) rotation in samples of pure 3-methylglutaric anhydride (1), pure 3-methylglutaric acid (2), and samples where the anhydride is slowly absorbing water from the air and converting to the acid [C6H8O3(1) + H2O → C6H10O4(2)]. The techniques are solid state 1H nuclear magnetic resonance (NMR) spin-lattice relaxation, single-crystal X-ray diffraction, electronic structure calculations in both isolated molecules and in clusters of molecules that mimic the crystal structure, field emission scanning electron microscopy, differential scanning calorimetry, and high resolution …
An Approximate Analytic Model Of A Star Cluster With Potential Escapers, Kathryne J. Daniel, Douglas C. Heggie, Anna Lisa Varri
An Approximate Analytic Model Of A Star Cluster With Potential Escapers, Kathryne J. Daniel, Douglas C. Heggie, Anna Lisa Varri
Physics Faculty Research and Scholarship
In the context of a star cluster moving on a circular galactic orbit, a “potential escaper” is a cluster star that has orbital energy greater than the escape energy, and yet is confined within the Jacobi radius of the stellar system. On the other hand analytic models of stellar clusters typically have a truncation energy equal to the cluster escape energy, and therefore explicitly exclude these energetically unbound stars. Starting from the landmark analysis performed by Hénon of periodic orbits of the circular Hill equations, we present a numerical exploration of the population of “non-escapers”, defined here as those stars …
Observations Of High Vibrational Levels Of The 4fσ 41Σ+ U State Of H2, Alexander M. Chartrand, Robert C. Ekey Jr., Elizabeth F. Mccormack
Observations Of High Vibrational Levels Of The 4fσ 41Σ+ U State Of H2, Alexander M. Chartrand, Robert C. Ekey Jr., Elizabeth F. Mccormack
Physics Faculty Research and Scholarship
Resonantly enhanced multiphoton ionization via the EF 1Σg+, v′ = 6 double-well state has been used to probe the energy region below the third dissociation limit of H2 where several high vibrational levels of the 41Σu+ state are expected. Theoretical ab initio potential energy curves for this state predict a deep inner well and shallow outer well where vibrational levels above v = 8 are expected to exhibit the double-well character of the state. Since the 41Σu+ state has f-state character, transitions to it from the …
Observations Of The High Vibrational Levels Of The B′′B̄ 1Σu+ State Of H2, Alexander M. Chartrand, W. Duan, R. C. Ekey, Elizabeth Mccormack
Observations Of The High Vibrational Levels Of The B′′B̄ 1Σu+ State Of H2, Alexander M. Chartrand, W. Duan, R. C. Ekey, Elizabeth Mccormack
Physics Faculty Research and Scholarship
Double-resonance laser spectroscopy via the E F 1Σg+, v'=6, J'=0-2 state was used to probe the high vibrational levels of the B"B-bar 1Σu+ state of molecular hydrogen. Resonantly-enhanced multiphoton ionization spectra were recorded by detecting ion production as a function of energy using a time of flight mass spectrometer. New measurements of energies for the v=51-66 levels for the B"B-bar state of H2 are reported, which, taken with previous results, span the v=46-69 vibrational levels. Results for energy levels are compared to theoretical close-coupled calculations [L. Wolniewicz, T. …
Observations Of The High Vibrational Levels Of The B′′B̄ 1Σ+U State Of H2, A. M. Chartrand, W. Duan, R. C. Ekey, Elizabeth Mccormack
Observations Of The High Vibrational Levels Of The B′′B̄ 1Σ+U State Of H2, A. M. Chartrand, W. Duan, R. C. Ekey, Elizabeth Mccormack
Physics Faculty Research and Scholarship
Double-resonance laser spectroscopy via the E F 1Σ+g, v' = 6, J' = 0–2 state was used to probe the high vibrational levels of the B′′B̄ 1Σ+u state of molecular hydrogen. Resonantly enhanced multiphotonionization spectra were recorded by detecting ion production as a function of energy using a time of flight mass spectrometer. New measurements of energies for the v = 51–66 levels for the B00B ̄ state of H2 are reported, which, taken with previous results, span the v = 46–69 vibrational levels. Results for energy levels are compared to theoretical close-coupled …
Methyl And T-Butyl Group Rotation In A Molecular Solid: 1h Nmr Spin-Lattice Relaxation And X-Ray Diffraction, Peter A. Beckmann, Curtis E. Moore, Arnold L. Rheingold
Methyl And T-Butyl Group Rotation In A Molecular Solid: 1h Nmr Spin-Lattice Relaxation And X-Ray Diffraction, Peter A. Beckmann, Curtis E. Moore, Arnold L. Rheingold
Physics Faculty Research and Scholarship
We report solid state 1H nuclear magnetic resonance spin-lattice relaxation experiments and X-ray diffractometry in 2-t-butyldimethylsilyloxy-6-bromonaphthalene. This compound offers an opportunity to simultaneously investigate, and differentiate between, the rotations of a t-butyl group [C(CH3)3] and its three constituent methyl groups (CH3) and, simultaneously, a pair of 'lone' methyl groups (attached to the Si atom). The solid state 1H relaxation experiments determine activation energies for these rotations. We review the models for the dynamics of both 'lone' methyl groups (ones whose rotation axes do not move on the NMR time scale) and models for the dynamics of the t-butyl group and …
1h And 19f Spin-Lattice Relaxation And Ch3 Or Cf3 Reorientation In Molecular Solids Containing Both H And F Atoms, Peter A. Beckmann, Andrew L. Rheingold
1h And 19f Spin-Lattice Relaxation And Ch3 Or Cf3 Reorientation In Molecular Solids Containing Both H And F Atoms, Peter A. Beckmann, Andrew L. Rheingold
Physics Faculty Research and Scholarship
The dynamics of methyl (CH3) and fluoromethyl (CF3) groups in organic molecular (van der Waals) solids can be exploited to survey their local environments. We report solid state 1H and 19F spin-lattice relaxationexperiments in polycrystalline 3-trifluoromethoxycinnamic acid, along with an X-ray diffraction determination of the molecular and crystal structure, to investigate the intramolecular and intermolecular interactions that determine the properties that characterize the CF3 reorientation. The molecule is of no particular interest; it simply provides a motionless backbone (on the nuclear magnetic resonance (NMR) time scale) to investigate CF3reorientation occurring on the NMR time scale. The effects of 19F–19F and …
Imaging The Dipole-Dipole Energy Exchange Between Ultracold Rubidium Rydberg Atoms, Donald Fahey, Thomas J. Carroll, Michael W. Noel
Imaging The Dipole-Dipole Energy Exchange Between Ultracold Rubidium Rydberg Atoms, Donald Fahey, Thomas J. Carroll, Michael W. Noel
Physics Faculty Research and Scholarship
The long-range, anisotropic nature of the interaction among atoms in an ultracold dipolar gas leads to a rich array of possibilities for studying many-body physics. In this work, an ultracold gas of highly excited atoms is used to study energy transport due to the long-range dipole-dipole interaction. A technique is developed to measure both the internal energy states of the interacting Rydberg atoms and their positions in space. This technique is demonstrated by observing energy exchange between two spatially separated groups of Rydberg atoms excited to two different internal states. Simulations confirm the general features of the energy transport in …