Physics Commons^™

Probing The Existence Of Energetically Degenerate Cluster Isomers By Chemical Tagging, Qian Wang, Qiang Sun, Puru Jena

Physics Publications

Current methods for identifying the ground state geometry of a cluster require synergy between theory and experiment. However, this becomes a difficult problem when the accuracy of the theoretical methods is not sufficient to distinguish between nearly degenerate isomers. Using density functional theory based calculations, we show that the near degeneracy between the planar and the cage structures can be lifted by tagging these with halogens and superhalogens moieties such as Cl and BO2. The energy of the planar Au16− isomer is lowered from 0.15 eV before tagging to 0.51–0.55 eV after tagging, thus providing a way to probe its …

Magnetism In Zno Nanowire With Fe/Co Codoping: First-Principles Density Functional Calculations, S. Ghosh, Q. Wang, G. P. Das, Puru Jena

Physics Publications

Using first-principles density functional calculations, at both generalized gradient approximation (GGA) and GGA+U levels we have investigated the electronic structure and magnetic properties of Fe/Co codoped ZnO nanowire. Here we have addressed some of the key issues such as, the preferable sites that Fe/Co can occupy, the coupling mechanism, and role of defects in coupling. We found that the spin alignment between the transition-metal atoms depends on their location. When Fe and Co atoms are nearest neighbors on the outer surface of the nanowire along [0001] direction is the lowest energy configuration with ferrimagnetic (FiM) ground state. At GGA level …

Communications: Chain And Double-Ring Polymeric Structures: Observation Of Alnh3n+1− (N=4–8) And Al4h14, Xiang Li, Andrej Grubisic, Kit H. Bowen, Anil K. Kandalam, Boggavarapu Kiran, Gerd Gantefor, Puru Jena

Physics Publications

A pulsed arc discharge source was used to prepare gas-phase, aluminum hydride cluster anions, AlnHm−, exhibiting enhanced hydrogen content. The maximum number of hydrogen atoms in AlnHm− species was m=3n+1 for n=5–8, i.e., AlnH3n+1−, and m=3n+2 for n=4, i.e., Al4H14−, as observed in their mass spectra. These are the most hydrogen-rich aluminum hydrides to be observed thus far, transcending the 3:1 hydrogen-to-aluminum ratio in alane. Even more striking, ion intensities for AlnHm− species with m=3n+1 and m=3n+2 hydrogen atoms were significantly higher than those of nearby AlnHm− mass peaks for which m<3n+1, i.e., the ion intensities for AlnH3n+1− and for Al4H14− deviated from the roughly bell-shaped ion intensity patterns seen for most AlnHm−species, in which m ranges from 1 to 3n. Calculations based on density functional theory showed that AlnH3n+1− clusters have chain and/or double-ring polymericstructures.

Demonstration Of A Neutral Atom Controlled-Not Quantum Gate, L. Isenhower, E. Urban, X. L. Zhang, A. T. Gill, T. Henage, Todd A. Johnson, T. G. Walker, M. Saffman

Physics Faculty Publications

We present the first demonstration of a CNOT gate between two individually addressed neutral atoms. Our implementation of the CNOT uses Rydberg blockade interactions between neutral atoms held in optical traps separated by >8  μm. Using two different gate protocols we measure CNOT fidelities of F=0.73 and 0.72 based on truth table probabilities. The gate was used to generate Bell states with fidelity F=0.48±0.06. After correcting for atom loss we obtain an a posteriori entanglement fidelity of F=0.58.

The Gas Team And Nasa (Aka Boil, Boil, Toil And Trouble), Get Away Special Team 2010

Education and Outreach

No abstract provided.

Imaging Live Cells Grown On A Three Dimensional Collagen Matrix Using Raman Microspectroscopy, Franck Bonnier, Peter Knief, Basil Lim, Aidan Meade, Jennifer Dorney, Kunal Bhattacharya, Fiona Lyng, Hugh Byrne

Articles

Three dimensional collagen gels have been used as matrices for the imaging of live cells by Raman spectroscopy. The study is conducted on a human lung adenocarcinoma (A549) and a spontaneously immortalized human epithelial keratinocyte (HaCaT) cell line. The lateral resolution of the system has been estimated to be

Oscillatory And Monotonic Modes Of Long-Wave Marangoni Convection In A Thin Film, Sergey Shklyaev, Mikhail Khenner, Alexei Alabuzhev

Mathematics Faculty Publications

We study long-wave Marangoni convection in a layer heated from below. Using the scaling k=O Bi, where k is the wave number and Bi is the Biot number, we derive a set of amplitude equations. Analysis of this set shows presence of monotonic and oscillatory modes of instability. Oscillatory mode has not been previously found for such direction of heating. Studies of weakly nonlinear dynamics demonstrate that stable steady and oscillatory patterns can be found near the stability threshold.

Temperature Trends And Episodic Changes Of The Middle Atmosphere Over Logan Utah With Consideration To Model Specification, Troy A. Wynn, Vincent B. Wickwar

Reports

A summary of the linear trends estimated from the USU Rayleigh Lidar (41.74o N, 118oW) temperature data set. The data set covers a time span from September, 1993 to August, 2003 and an altitude range of 45 to 80 km. The data set includes 584 data points at 45 km to 580 data points at 80 km. Cooling trend profiles are calculated and compared to results from other researchers. Collinearity and bias are also considered as issues that could affect the regression results. Also considered is the possibility that the Mt. Pinatubo eruption has influenced temperature trend estimates. This is …

Alignment And Orientation Of Diatomic Molecules Induced By Polarized Electron Impact, Jack W. Maseberg, Timothy J. Gay

Timothy J. Gay Publications

We report measurements of linear and circular fluorescence polarizations for molecular transitions in H₂, D₂, and N₂ induced by spin-polarized electron impact. Circular polarizations resulting from some Fulcher-α transitions in H₂ and D₂ are found to be significant, while the null results from nitrogen’s second positive system are consistent with an earlier measurement by the Münster group. We compare this nitrogen data to that from our previous study of nitrogen’s first negative system. Emphasis is placed on understanding the mechanisms that cause the values of circular polarization from N₂ to be relatively …

Research Report 2010, College Of Arts And Sciences

Physics Research Reports

• Introduction
• From the Chairperson
• Astronomy
• Atomic and Molecular Physics
• Condensed Matter Physics
• Physics Education
• Research and Public Lectures at WMU
• Personnel January 1-December 31, 2010

Controlled Assembly And Electronic Transport Studies Of Solution Processed Carbon Nanotube Devices, Paul Stokes

Electronic Theses and Dissertations

Developing techniques for the parallel fabrication of Complementary Metal Oxide Semiconductor (CMOS) compatible single walled carbon nanotube (SWNT) electronic devices is of great importance for nanoelectronic applications. In this thesis, solution processed SWNTs in combination with AC dielectrophoresis (DEP) were utilized to fabricate CMOS compatible SWNT field effect transistors (FETs) and single electron transistors (SETs) with high yield and their detailed electronic transport properties were studied. Solution processing of SWNTs is attractive not only for the high throughput and parallel manufacturing of SWNT devices but also due to the ease of processing at room temperature, and compatibility with various substrates. …

Search For The Decay Ds To Omega L Nu, Jin Zhu

Wayne State University Dissertations

This analysis searches for a new type of rare decay of the charmed mesons,

which would provide direct evidence for the presence of Fock states inside

hadrons.

We use 586pb of e+e- collisions at the Cornell Electron Storage

Ring (CESR), at \sqrt{s}=4.17 GeV, recorded with the Cleo-c detector.

A limit on the branching ratio Ds to omega e nu is found, at 0.231\%

(95\% C.L.).

Measuring The Nanomechanics Of Nanoconfined Water Layers, Shah Haidar Khan

Wayne State University Dissertations

Nanoconfined water has been the subject of special interest due to its applications in various fields such as biology, geology, medicine, and engineering tribology. While there is a general agreement on the layering of water molecules along atomically smooth surfaces, the behavior and properties of nanoconfined water is still poorly understood. A significant controversy exists whether there is a phase transformation imposed by confinement. We have measured the stiffness and damping coefficient of nanoconfined water using a small amplitude (0.5-1 Å) atomic force microscope. The results were analyzed with the help of two viscoelastic models, the Kelvin model and the …

Dihadron Fragmentation Functions In Proton-Proton Collisions At The Relativistic Heavy Ion Collider (Rhic), Muhammad Elnimr

Wayne State University Dissertations

Measurements of azimuthal correlations at the Relativistic Heavy Ion Collider (RHIC) have shown an away-side that is suppressed in Au+Au collisions compared to proton+proton/Deuteron+proton collisions. Such suppression is taken as a signature of the predicted QCD dense medium. However, the near-side of the azimuthal correlations shows little modification. The near-side of such correlations is related to the ratio of the dihadron fragmentation function to the single one. As such, dihadron fragmentation functions shall provide a better basis for the interpretation of the near-side correlations. Dihadron fragmentation functions also also provide a baseline of such measurements in heavy ion collisions.

Permittivity And Permeability Of Fe(Tb) Nanoparticles And Their Microwave Absorption In The 2–18 Ghz Range, Z. Han, D. Li, M. Tong, X. Wei, Ralph Skomski, W. Liu, Z. D. Zhang, David J. Sellmyer

Ralph Skomski Publications

The permittivity and permeability of the Tb-doped and undoped Fe core-shell nanoparticles were investigated for frequencies from 2 to 18 GHz. The particles were synthesized by arc discharge and contain some oxygen, probably in the form of Fe₂O₃, Fe₃O₄, and Tb₂O₃, whereas the core material is Fe. Both the electromagnetic materials constants and the morphology of the Fe nanoparticles are changed by Tb addition, which gives rise to the shifts to higher frequencies and thinner thicknesses of the maximum microwave absorption in the Tb-doped Fe nanoparticles.

Permanent Magnetism Of Dense-Packed Nanostructures, Ralph Skomski, Yi Liu, Jeffrey E. Shield, George C. Hadjipanayis, David J. Sellmyer

Ralph Skomski Publications

The effect of nanostructuring on magnetostatic interactions in permanent magnets is investigated by model calculations. Emphasis is on the energy product as a function of packing fraction of the magnetic phase, of the magnet’s macroscopic shape, and of the nanoscale feature size. The main difference between nanostructured and macroscopic magnetic bodies, namely, the transition between coherent and incoherent reversal, has a far-reaching impact on demagnetizing field and energy product. For small magnet sizes, the energy product is substantially enlarged, up to μ₀M_s²4 for soft magnetic materials, but this effect is difficult to exploit in real …

Magnetism Of Core-Shell Ti:Tio Nanoparticles, Xiaohui Wei, Ralph Skomski, Balamurugan Balasubramanian, David J. Sellmyer

Ralph Skomski Publications

Ti nanoparticles were produced using a cluster-deposition method. Ti:TiO core-shell structures were fabricated by partially oxidizing the surface of the Ti nanoparticles produced by a cluster-deposition system via multistep annealing at 250 °C in oxygen. X-ray diffraction and transmission-electron microscopy studies reveal an increase in the thickness of the TiO shell with increasing annealing time. The magnetic moment and the coercivity of the core-shell nanoparticles increase with the TiO shell thickness, which is consistent with homogenous bulk defects in TiO. The core-shell nanoparticles display an abnormal hysteresis loop, which probably reflects a combination of antiferromagnetic exchange and magnetocrystalline anisotropy.

Magnetic Antiphase Domains In Co/Ru/Co Trilayers, Zhen Li, Ralph Skomski, Steven A. Michalski, Lanping Yue, Roger D. Kirby

Ralph Skomski Publications

Ultrathin Co/Ru/Co trilayers are investigated experimentally by magnetization curves and magnetic-force microscopy (MFM). Emphasis is on the domain-wall fine structure of antiphase domain walls in the films. The trilayers are produced by sputtering and consist of two Co layers of equal thickness (5 nm), exchange-coupled through a Ru layer of variable thickness. The sign and magnitude of the interlayer exchange are tuned by the thickness of the Ru interlayer. The exchange and its distribution are investigated by measurements of the static magnetization curves. For a Ru thickness of 0.4 nm, the exchange is predominantly antiferromagnetic and the MFM images show …

Magnetic Anisotropy In Itinerant Magnets, Ralph Skomski, Arti Kashyap, A. Solanki, Axel Enders, David J. Sellmyer

Ralph Skomski Publications

The structural dependence of the magnetocrystalline anisotropy of itinerant permanent magnets (or nanostructures of iron-series 3d elements) is investigated by model and tight-binding calculations. Magnetic nanostructures yield strong oscillations of the anisotropy as a function of the number of d electrons per atom, which can be tuned by alloying. While interatomic hopping is usually more important in metals than crystal-field interactions, we find substantial crystal-field corrections for some configurations, especially for the atomic square. Finally, we compare our results with Néel model.

Magnetic Susceptibility Of Nanoscale Kondo Systems, Ralph Skomski, R. Zhang, Parashu Kharel, Axel Enders, Sy_Hwang Liou, D. J. Sellmyer

Axel Enders Publications

The mesoscopic Kondo effect in metallic nanoparticles containing a magnetic impurity is investigated by model calculations. A Maxwell–Garnett approach is used to approximately determine the resistivity of doped nanoparticles in a matrix, and the magnetic susceptibility is estimated from the confinement of the conduction electrons. Conductivity measurements of nanoparticles embedded in a matrix are difficult to realize, because metallic matrices distort the Kondo cloud, whereas insulating or semiconducting matrices yield a very weak signal. By comparison, susceptibility measurements do not suffer from these shortcomings. The Kondo effect survives in nanoparticles even if the cluster size is much smaller than the …