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Solid State Proton Spin-Lattice Relaxation In Polycrystalline Methylphenanthrenes. Iv. 1,4-Dimethylphenanthrene, Peter A. Beckmann Mar 2019

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 ...


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 Jan 2019

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 ...


Constraints On Radial Migration In Spiral Galaxies - Ii. Angular Momentum Distribution And Preferential Migration, Kathryne J. Daniel, Rosemary F. G. Wyse Jan 2018

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 ...


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 Jan 2018

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 Jan 2018

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 ...


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 Jan 2018

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 ...


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 Jan 2018

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 ...


Note: Methyl And T-Butyl Group Rotation In Van Der Waals Solids, Peter A. Beckmann, Arnold L. Rheingold, Jason Schmink Jan 2018

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.


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 Dec 2017

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 2Σg+ ground state, and electronically ...


Continuity Of Heavy Rydberg Behaviour In The Ungerade Ion-Pair States Of H2, Alexander M. Chartrand, Robert J. Donovan, Kenneth P. Lawley, Elizabeth Mccormack May 2017

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.


An Approximate Analytic Model Of A Star Cluster With Potential Escapers, Kathryne J. Daniel, Douglas C. Heggie, Anna Lisa Varri Jan 2017

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 ...


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 Jan 2017

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 ...


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 Jan 2017

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 1H NMR spectroscopy. The solid state 1H spin-lattice ...


Observations Of High Vibrational Levels Of The 4fσ 41Σ+ U State Of H2, Alexander M. Chartrand, Robert C. Ekey Jr., Elizabeth F. Mccormack Jul 2016

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 ground state are nominally forbidden. However ...


Observations Of The High Vibrational Levels Of The B′′B̄ 1Σu+ State Of H2, Alexander M. Chartrand, W. Duan, R. C. Ekey, Elizabeth Mccormack Jan 2016

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. Orlikowski ...


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 Jan 2016

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 ...


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 Jan 2016

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 ...


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 Jan 2016

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 calculations [L. Wolniewicz, T ...


Imaging The Dipole-Dipole Energy Exchange Between Ultracold Rubidium Rydberg Atoms, Donald Fahey, Thomas J. Carroll, Michael W. Noel Jan 2015

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 ...


Magnetohydrodynamic Turbulence: Observation And Experiment, M. R. Brown, David A. Schaffner, P. J. Weck Jan 2015

Magnetohydrodynamic Turbulence: Observation And Experiment, M. R. Brown, David A. Schaffner, P. J. Weck

Physics Faculty Research and Scholarship

We provide a tutorial on the paradigms and tools of magnetohydrodynamic (MHD) turbulence. The principal paradigm is that of a turbulent cascade from large scales to small, resulting in power law behavior for the frequency power spectrum for magnetic fluctuations EB(f) . We will describe five useful statistical tools for MHD turbulence in the time domain: the temporal autocorrelation function, the frequency power spectrum, the probability distribution function of temporal increments, the temporal structure function, and the permutation entropy. Each of these tools will be illustrated with an example taken from MHD fluctuations in the solar wind. A single dataset ...


Methoxy And Methyl Group Rotation: Solid State Nmr 1h Spin-Lattice Relaxation, Electronic Structure Calculations, Xray Diffractometry, And Scanning Electron Microscopy, Peter A. Beckmann, Clelia W. Mallory, Frank B. Mallory, Arnold L. Rheingold, Xianlong Wang Jan 2015

Methoxy And Methyl Group Rotation: Solid State Nmr 1h Spin-Lattice Relaxation, Electronic Structure Calculations, Xray Diffractometry, And Scanning Electron Microscopy, Peter A. Beckmann, Clelia W. Mallory, Frank B. Mallory, Arnold L. Rheingold, Xianlong Wang

Physics Faculty Research and Scholarship

We report solid-state (1) H nuclear magnetic resonance (NMR) spin-lattice relaxation experiments, X-ray diffractometry, field-emission scanning electron microscopy, and both single-molecule and cluster ab initio electronic structure calculations on 1-methoxyphenanthrene (1) and 3-methoxyphenanthrene (2) to investigate the rotation of the methoxy groups and their constituent methyl groups. The electronic structure calculations and the (1) H NMR relaxation measurements can be used together to determine barriers for the rotation of a methoxy group and its constituent methyl group and to develop models for the two coupled motions.


Quantum Interference In The Field Ionization Of Rydberg Atoms, Rachel Feynman, Jacob Hollingsworth, Michael Vennettilli, Tamas Budner, Ryan Zmiewski, Donald Fahey, Thomas J. Carroll, Michael W. Noel Jan 2015

Quantum Interference In The Field Ionization Of Rydberg Atoms, Rachel Feynman, Jacob Hollingsworth, Michael Vennettilli, Tamas Budner, Ryan Zmiewski, Donald Fahey, Thomas J. Carroll, Michael W. Noel

Physics Faculty Research and Scholarship

We excite ultracold rubidium atoms in a magneto-optical trap to a coherent superposition of the three |mj | sublevels of the 37d5/2 Rydberg state. After some delay, during which the relative phases of the superposition components can evolve, we apply an electric field pulse to ionize the Rydberg electron and send it to a detector. The electron traverses many avoided crossings in the Stark levels as it ionizes. The net effect of the transitions at these crossings is to mix the amplitudes of the initial superposition into the same final states at ionization. Similar to a Mach-Zehnder interferometer, the three ...


Permutation Entropy And Statistical Complexity Analysis Of Turbulence In Laboratory Plasmas And The Solar Wind, P. J. Weck, David A. Schaffner, M. R. Brown Jan 2015

Permutation Entropy And Statistical Complexity Analysis Of Turbulence In Laboratory Plasmas And The Solar Wind, P. J. Weck, David A. Schaffner, M. R. Brown

Physics Faculty Research and Scholarship

The Bandt-Pompe permutation entropy and the Jensen-Shannon statistical complexity are used to analyze fluctuating time series of three different turbulent plasmas: the magnetohydrodynamic (MHD) turbulence in the plasma wind tunnel of the Swarthmore Spheromak Experiment (SSX), drift-wave turbulence of ion saturation current fluctuations in the edge of the Large Plasma Device (LAPD), and fully developed turbulent magnetic fluctuations of the solar wind taken from the Wind spacecraft. The entropy and complexity values are presented as coordinates on the CH plane for comparison among the different plasma environments and other fluctuation models. The solar wind is found to have the highest ...


Nonexponential 1h Spin-Lattice Relaxation And Methyl Group Rotation In Molecular Solids, Peter A. Beckmann Jan 2015

Nonexponential 1h Spin-Lattice Relaxation And Methyl Group Rotation In Molecular Solids, Peter A. Beckmann

Physics Faculty Research and Scholarship

We report a quantitative measure of the nonexponential 1H spin-lattice relaxation resulting from methyl group (CH3) rotation in six polycrystalline van der Waals solids. We briefly review the subject in general to put the report in context. We then summarize several significant issues to consider when reporting 1H or 19F spin-lattice relaxation measurements when the relaxation is resulting from the rotation of a CH3 or CF3 group in a molecular solid.


I-127 And Pb-207 Solid-State Nmr Spectroscopy And Nuclear Spin Relaxation In Lead Iodide: A Preliminary Study, R. E. Taylor, Peter A. Beckmann, Shi Bai, C. Dybowski Jan 2014

I-127 And Pb-207 Solid-State Nmr Spectroscopy And Nuclear Spin Relaxation In Lead Iodide: A Preliminary Study, R. E. Taylor, Peter A. Beckmann, Shi Bai, C. Dybowski

Physics Faculty Research and Scholarship

Lead iodide is a layered structure that experiences polytypism. The 2H polytype contains high rates of iodine vacancies but retains its stoichiometry. This characteristic feature makes it potentially useful for many practical applications. The hopping of iodine ions among vacancies is the dominant motion in the 2H polytype. We present a preliminary 127I and 207Pb solid-state nuclear magnetic resonance (NMR) spectroscopy and spin–lattice relaxation study of the 2H polytype below 400 K. We present reasonable models for the solid-state NMR results in terms of the effects of iodine hopping and lattice vibrations.


Observation Of Turbulent Intermittency Scaling With Magnetic Helicity In An Mhd Plasma Wind Tunnel, David A. Schaffner, A. Wan, M. R. Brown Jan 2014

Observation Of Turbulent Intermittency Scaling With Magnetic Helicity In An Mhd Plasma Wind Tunnel, David A. Schaffner, A. Wan, M. R. Brown

Physics Faculty Research and Scholarship

The intermittency in turbulent magnetic field fluctuations has been observed to scale with the amount of magnetic helicity injected into a laboratory plasma. An unstable spheromak injected into the MHD wind tunnel of the Swarthmore Spheromak Experiment displays turbulent magnetic and plasma fluctuations as it relaxes into a Taylor state. The level of intermittency of this turbulence is determined by finding the flatness of the probability distribution function of increments for magnetic pickup coil fluctuations B_ðtÞ. The intermittency increases with the injected helicity, but spectral indices are unaffected by this variation. While evidence is provided which supports the hypothesis that ...


Solid State 1 H Spin - Lattice Relaxation And Isolated - Molecule And Cluster Electronic Structure Calculations In Organic Molecular Solids: The Relationship Between Structure And Methyl Group And T - Butyl Group Rotation, Xianlong Wang, Frank B. Mallory, Clelia W. Mallory, Hosanna R. Odhner, Peter A. Beckmann Jan 2014

Solid State 1 H Spin - Lattice Relaxation And Isolated - Molecule And Cluster Electronic Structure Calculations In Organic Molecular Solids: The Relationship Between Structure And Methyl Group And T - Butyl Group Rotation, Xianlong Wang, Frank B. Mallory, Clelia W. Mallory, Hosanna R. Odhner, Peter A. Beckmann

Physics Faculty Research and Scholarship

We report ab initio density functional theory electronic structure calculations of rotational barriers for t-butyl groups and their constituent methyl groups both in the isolated molecules and in central molecules in clusters built from the X-ray structure in four t-butyl aromatic compounds. The X-ray structures have been reported previously. We also report and interpret the temperature dependence of the solid state 1H nuclear magnetic resonance spin-lattice relaxation rate at 8.50, 22.5, and 53.0 MHz in one of the four compounds. Such experiments for the other three have been reported previously. We compare the computed barriers for methyl ...


Double Resonance Spectroscopy Of The D1Πu+ And B''B-Bar 1Σu+ States Near The Third Dissociation Threshold Of H2, R. C. Ekey, A. E. Cordova, W. Duan, Alexander M. Chartrand, Elizabeth Mccormack Nov 2013

Double Resonance Spectroscopy Of The D1Πu+ And B''B-Bar 1Σu+ States Near The Third Dissociation Threshold Of H2, R. C. Ekey, A. E. Cordova, W. Duan, Alexander M. Chartrand, Elizabeth Mccormack

Physics Faculty Research and Scholarship

Double-resonance laser spectroscopy via the E, F 1Σg+, v' = 6, J' state was used to probe the energy region below the third dissociation limit of molecular hydrogen. Resonantly enhanced multi-photon ionization spectra were recorded by detecting ion production as a function of energy using a time-of-flight mass spectrometer. Energies and line widths for the v = 14–17 levels of the D1Πu+ state of H2 are reported and compared to experimental data obtained by using VUV synchrotron light excitation (Dickenson et al. 2010 J. Chem. Phys. 133 144317) and fully ab initio non-adiabatic calculations of ...


Room-Temperature Multiferroic Hexagonal Lufeo3 Films, Wenbin Wang, Jun Zhao, Wenbo Wang, Zheng Gai, Nina Balke, Miaofang Chi, Ho Nyung Lee, Wei Tian, Leyi Zhu, Xuemei Cheng, David J. Keavney, Jieyu Yi, Thomas Z. Ward, Paul C. Snijders, Hans M. Christen, Weida Wu, Jian Shen, Xiaoshan Xu Jun 2013

Room-Temperature Multiferroic Hexagonal Lufeo3 Films, Wenbin Wang, Jun Zhao, Wenbo Wang, Zheng Gai, Nina Balke, Miaofang Chi, Ho Nyung Lee, Wei Tian, Leyi Zhu, Xuemei Cheng, David J. Keavney, Jieyu Yi, Thomas Z. Ward, Paul C. Snijders, Hans M. Christen, Weida Wu, Jian Shen, Xiaoshan Xu

Physics Faculty Research and Scholarship

The crystal and magnetic structures of single-crystalline hexagonal LuFeO3 films have been studied using x-ray, electron, and neutron diffraction methods. The polar structure of these films are found to persist up to 1050 K; and the switchability of the polar behavior is observed at room temperature, indicating ferroelectricity. An antiferromagnetic order was shown to occur below 440 K, followed by a spin reorientation resulting in a weak ferromagnetic order below 130 K. This observation of coexisting multiple ferroic orders demonstrates that hexagonal LuFeO3 films are room-temperature multiferroics.


Tuning Vortex Confinement By Magnetic Domains In A Superconductor/Ferromagnet Bilayer, Marta Z. Cieplak, Z. Adamus, M. Kończykowski, L. Y. Zhu, Xuemei Cheng, C. L. Chien Jan 2013

Tuning Vortex Confinement By Magnetic Domains In A Superconductor/Ferromagnet Bilayer, Marta Z. Cieplak, Z. Adamus, M. Kończykowski, L. Y. Zhu, Xuemei Cheng, C. L. Chien

Physics Faculty Research and Scholarship

We use a line of miniature Hall sensors to study the effect of magnetic-domain-induced vortex confinement on the flux dynamics in a superconductor/ferromagnet bilayer. A single tunable bilayer is built of a ferromagnetic Co/Pt multilayer with perpendicular magnetic anisotropy and a superconducting Nb layer, with the insulating layer in-between to avoid the proximity effect. The magnetic-domain patterns of various geometries are reversibly predefined in the Co/Pt multilayer using the appropriate magnetization procedure. The magnetic-domain geometry strongly affects vortex dynamics, leading to geometry-dependent trapping of vortices at the sample edge, nonuniform flux penetration, and strongly nonuniform critical current ...