Open Access. Powered by Scholars. Published by Universities.®

Atomic, Molecular and Optical Physics Commons™

Open Access. Powered by Scholars. Published by Universities.®

2009

Discipline
Institution
Keyword
Publication
Publication Type

Articles 1 - 30 of 44

Full-Text Articles in Atomic, Molecular and Optical Physics

Midwave Infrared Imaging Fourier Transform Spectrometry Of Combustion Plumes, Kenneth C. Bradley Dec 2009

Midwave Infrared Imaging Fourier Transform Spectrometry Of Combustion Plumes, Kenneth C. Bradley

Theses and Dissertations

A midwave infrared (MWIR) imaging Fourier transform spectrometer (IFTS) was used to successfully capture and analyze hyperspectral imagery of combustion plumes. Jet engine exhaust data from a small turbojet engine burning diesel fuel at a flow rate of 300 cm3/min was collected at 1 cm−1 resolution from a side-plume vantage point on a 200x64 pixel window at a range of 11.2 meters. Spectral features of water, CO, and CO2 were present, and showed spatial variability within the plume structure. An array of thermocouple probes was positioned within the plume to aid in temperature analysis. A single-temperature …

Go to article

Pair Creation Rates For One-Dimensional Fermionic And Bosonic Vacua, T Cheng, M R. Ware, Q Su, Rainer Grobe Dec 2009

Pair Creation Rates For One-Dimensional Fermionic And Bosonic Vacua, T Cheng, M R. Ware, Q Su, Rainer Grobe

Faculty publications – Physics

We compare the creation rates for particle-antiparticle pairs produced by a supercritical force field for fermionic and bosonic model systems. The rates obtained from the Dirac and Klein-Gordon equations can be computed directly from the quantum-mechanical transmission coefficients describing the scattering of an incoming particle with the supercritical potential barrier. We provide a unified framework that shows that the bosonic rates can exceed the fermionic ones, as one could expect from the Pauli-exclusion principle for the fermion system. This imbalance for small but supercritical forces is associated with the occurrence of negative bosonic transmission coefficients of arbitrary size for the …

Go to article

Constructing A Magneto-Optical Trap For Cold Atom Trapping, Eric S. Muckley Dec 2009

Constructing A Magneto-Optical Trap For Cold Atom Trapping, Eric S. Muckley

Physics

A magneto-optical trap, or MOT, is a device that traps atoms between three pairs of opposing perpendicular laser beams for cooling the atoms to temperatures near absolute zero. The MOT uses Doppler cooling and a magnetic quadrupole field to trap the atoms; in our case, Rb87 atoms. In the future, the MOT will be used in experiments pertaining to the advancement of quantum computing. In this paper, I explain some of the processes required for construction and operation of the MOT.

Go to article

Simulations Of The Dipole-Dipole Interaction Between Two Spatially Separated Groups Of Rydberg Atoms, Thomas J. Carroll, Christopher Daniel, Leah Hoover, Timothy Sidie, Michael W. Noel Nov 2009

Simulations Of The Dipole-Dipole Interaction Between Two Spatially Separated Groups Of Rydberg Atoms, Thomas J. Carroll, Christopher Daniel, Leah Hoover, Timothy Sidie, Michael W. Noel

Physics and Astronomy Faculty Publications

The dipole-dipole interaction among ultracold Rydberg atoms is simulated. We examine a general interaction scheme in which two atoms excited to the x and x states are converted to y and y states via a Förster resonance. The atoms are arranged in two spatially separated groups, each consisting of only one species of atom. We monitor the state mixing by recording the fraction of atoms excited to the y state as the distance between the two groups is varied. With zero detuning a many-body effect that relies on always resonant interactions causes the state mixing to have a finite range. …

Go to article

Fragmentation Properties Of Three-Membered Ring Heterocyclic Molecules By Partial Ion Yield Spectroscopy: C2h4o And C2h4s, Wayne C. Stolte, I. Dumitriu, S-W Yu, Gunnar Ohrwall, Maria Novella Piancastelli, Dennis W. Lindle Nov 2009

Fragmentation Properties Of Three-Membered Ring Heterocyclic Molecules By Partial Ion Yield Spectroscopy: C2h4o And C2h4s, Wayne C. Stolte, I. Dumitriu, S-W Yu, Gunnar Ohrwall, Maria Novella Piancastelli, Dennis W. Lindle

Chemistry and Biochemistry Faculty Research

We investigated the photofragmentation properties of two three-membered ring heterocyclic molecules, C2H4O and C2H4S, by total and partial ion yield spectroscopy. Positive and negative ions have been collected as a function of photon energy around the C 1s and O 1s ionization thresholds in C2H4O, and around the S 2p and C 1s thresholds in C2H4S. We underline similarities and differences between these two analogous systems. We present a new assignment of the spectral features around the C K-edge and the sulfur L2 …

Go to article

Signal Classification In Fading Channels Using Cyclic Spectral Analysis, Zhiqiang Wu, Eric C. Like, Vasu D. Chakravarthy, Paul Ratazzi Sep 2009

Signal Classification In Fading Channels Using Cyclic Spectral Analysis, Zhiqiang Wu, Eric C. Like, Vasu D. Chakravarthy, Paul Ratazzi

Student Publications

Cognitive Radio (CR), a hierarchical Dynamic Spectrum Access (DSA) model, has been considered as a strong candidate for future communication systems improving spectrum efficiency utilizing unused spectrum of opportunity. However, to ensure the effectiveness of dynamic spectrum access, accurate signal classification in fading channels at low signal to noise ratio is essential. In this paper, a hierarchical cyclostationary-based classifier is proposed to reliably identify the signal type of a wide range of unknown signals. The proposed system assumes no a priori knowledge of critical signal statistics such as carrier frequency, carrier phase, or symbol rate. The system is designed with …

Go to article

Experimental And Theoretical Investigation Of Molecular Field Effects By Polarization-Resolved Resonant Inelastic X-Ray Scattering, Stephane Carniato, Renaud Guillemin, Wayne C. Stolte, Loic Journel, Richard Taieb, Dennis W. Lindle, Marc Simon Sep 2009

Experimental And Theoretical Investigation Of Molecular Field Effects By Polarization-Resolved Resonant Inelastic X-Ray Scattering, Stephane Carniato, Renaud Guillemin, Wayne C. Stolte, Loic Journel, Richard Taieb, Dennis W. Lindle, Marc Simon

Chemistry and Biochemistry Faculty Research

We present a combined theoretical and experimental study of molecular field effects on molecular core levels. Polarization-dependent resonant inelastic x-ray scattering is observed experimentally after resonant K-shell excitation of CF3Cl and HCl. We explain the linear dichroism observed in spin-orbit level intensities as due to molecular field effects, including singlet-triplet exchange, and interpret this behavior in terms of population differences in the 2px,y,z inner-shell orbitals. We investigate theoretically the different factors that can affect the electronic populations and the dynamical R dependence of the spin-orbit ratio. Finally, the results obtained are used to interpret the L-shell …

Go to article

Structural Role Of Pseudouridines In The Peptidyl Transferase Center Of Human 28s Ribosomal Rna, Chris Mart Aug 2009

Structural Role Of Pseudouridines In The Peptidyl Transferase Center Of Human 28s Ribosomal Rna, Chris Mart

All Theses

The human ribosome is an RNA-protein complex responsible for protein synthesis in the cell. Crystal structures of bacterial ribosomes solved to date depict no protein sidechains within the catalytic core, or peptidyl transferase center (PTC). This region of the human ribosome comprises approximately 230 highly conserved nucleotides. Notably, several of the uridine bases clustered within the human PTC are post-transcriptionally modified to pseudouridines, as compared with bacterial analogues. Pseudouridines are base-rotated uridines, linked to their sugar moieties through C5-C1' linkages, affording additional hydrogen-bond donor groups at the N1 position of their rings. A connection was recently made between the absence …

Go to article

Fluorescence Polarization Of Atomic, Dissociated Atomic, And Molecular Transitions Induced By Spin-Polarized Electron Impact, Jack W. Maseberg Aug 2009

Fluorescence Polarization Of Atomic, Dissociated Atomic, And Molecular Transitions Induced By Spin-Polarized Electron Impact, Jack W. Maseberg

Department of Physics and Astronomy: Dissertations, Theses, and Student Research

Excitation of atoms by spin-polarized electron impact yields fluorescence that can generally exhibit both linear and circular polarization. For experiments where the scattered electrons are not detected, symmetry requires that the electron beam be spin polarized in order for non-zero circular polarization to be observed. Extensive theoretical and experimental investigations have been performed regarding fluorescence polarizations (Stokes parameters) resulting from spin-polarized electron impact excitation of atoms. Measurement of fluorescence polarization provides insight into the angular momentum coupling that exists in the atomic state of interest. It also enables the measurement of electron spin polarization and experimental benchmarking of theoretical atomic …

Go to article

Thermodynamic Stability Of Transition States In Nanosystems, Alexander Umantsev Jul 2009

Thermodynamic Stability Of Transition States In Nanosystems, Alexander Umantsev

Chemistry and Physics Faculty Working Papers

We present a theory which shows that, in a closed system of fixed volume capable of undergoing a phase transition, the transition state can be thermodynamically stable against the bulk phases if a certain material parameters criterion is fulfilled. In a small system below the critical size the transition state turns into a globally stable phase that can be observed experimentally. This effect is analogous to stabilization of icosahedral structures in clusters of certain sizes and energies. Stabilization of the transition state in small systems of limited resources allows us to conjecture that, in the case of a melting/freezing transition …

Go to article

Creation Of Multiple Electron-Positron Pairs In Arbitrary Fields, T Cheng, Q Su, Rainer Grobe Jul 2009

Creation Of Multiple Electron-Positron Pairs In Arbitrary Fields, T Cheng, Q Su, Rainer Grobe

Faculty publications – Physics

We examine the spontaneous breakdown of the matter vacuum triggered by an external force of arbitrary strength and spatial and temporal variations. We derive a nonperturbative framework that permits the computation of the complete time evolution of various multiple electron-positron pair probabilities. These time-dependent probabilities can be computed from a generating function as well as from solutions to a set of ratelike equations with coupling constants determined by the single-particle solutions to the time-dependent Dirac equation. This approach might be of relevance to the planned experiments to observe for the first time the laser-induced breakdown process of the vacuum.

Go to article

Sum Rules And Universality In Electron-Modulated Acoustic Phonon Interaction In A Free-Standing Semiconductor Plate, Shigeyasu Uno, Darryl H. Yong, Nobuya Mori Jun 2009

Sum Rules And Universality In Electron-Modulated Acoustic Phonon Interaction In A Free-Standing Semiconductor Plate, Shigeyasu Uno, Darryl H. Yong, Nobuya Mori

All HMC Faculty Publications and Research

Analysis of acoustic phonons modulated due to the surfaces of a free-standing semiconductor plate and their deformation-potential interaction with electrons are presented. The form factor for electron-modulated acoustic phonon interaction is formulated and analyzed in detail. The form factor at zero in-plane phonon wave vector satisfies sum rules regardless of electron wave function. The form factor is larger than that calculated using bulk phonons, leading to a higher scattering rate and lower electron mobility. When properly normalized, the form factors lie on a universal curve regardless of plate thickness and material.

Go to article

Pressure-Driven Transport Of Particles Through A Converging-Diverging Microchannel, Ye Ai, Sang W. Joo, Yingtao Jiang, Xiangchun Xuan, Shizhi Qian Jun 2009

Pressure-Driven Transport Of Particles Through A Converging-Diverging Microchannel, Ye Ai, Sang W. Joo, Yingtao Jiang, Xiangchun Xuan, Shizhi Qian

Mechanical Engineering Faculty Research

Pressure-driven transport of particles through a symmetric converging-diverging microchannel is studied by solving a coupled nonlinear system, which is composed of the Navier–Stokes and continuity equations using the arbitrary Lagrangian–Eulerian finite-element technique. The predicted particle translation is in good agreement with existing experimental observations. The effects of pressure gradient, particle size, channel geometry, and a particle’s initial location on the particle transport are investigated. The pressure gradient has no effect on the ratio of the translational velocity of particles through a converging-diverging channel to that in the upstream straight channel. Particles are generally accelerated in the converging region and then …

Go to article

Experimental Studies Of Nacs, Seth T. Ashman, C. M. Wolfe, J. P. Huennekens May 2009

Experimental Studies Of Nacs, Seth T. Ashman, C. M. Wolfe, J. P. Huennekens

Engineering & Physics Faculty Publications

We present experimental studies of excited electronic states of the NaCs molecule that are currently underway in our laboratory. The optical-optical double resonance method is used to obtain Doppler-free excitation spectra for several excited states. These data are being used to obtain RydbergKlein-Rees (RKR) or Inverse Perturbation Approach (IPA) potential curves for these states. We are also trying to map the bound portion of the 1(a) 3Σ + potential using resolved laser-induced fluorescence and Fourier transform spectroscopy to record transitions into the shallow well. Bound-free spectra from single ro-vibrational levels of electronically excited states to the repulsive wall of the …

Go to article

Polarization Spectroscopy And Collisions In Nak, Seth T. Ashman, C. M. Wolfe, J. Huennekens, B. Beser, J. Bai, A. M. Lyyra May 2009

Polarization Spectroscopy And Collisions In Nak, Seth T. Ashman, C. M. Wolfe, J. Huennekens, B. Beser, J. Bai, A. M. Lyyra

Engineering & Physics Faculty Publications

We report current work to study transfer of population and orientation in collisions of NaK molecules with argon and potassium atoms using polarization labeling (PL) and laser-induced fluorescence (LIF) spectroscopy. In the PL experiment, a circularly polarized pump laser excites a specific NaK A1Σ +(v=16, J) ← X1Σ +(v=0, J ± 1) transition, creating an orientation (non-uniform MJ level distribution) in both levels. The linear polarized probe laser is scanned over various 3 1Π(v=8, J 0 ± 1) ← A1Σ +(v=16, J 0 ) transitions. The probe laser passes through a crossed linear polarizer before detection, and signal is recorded …

Go to article

Imaging Second-Harmonic Radiation And Scattering Patterns In Zno Micro/Nanostructures, Katrina Marie Geren May 2009

Imaging Second-Harmonic Radiation And Scattering Patterns In Zno Micro/Nanostructures, Katrina Marie Geren

Graduate Theses and Dissertations

The optical characteristics of ZnO nanostructures have recently garnered interest due to the inclusion of these structures in many nanoscale optical and optoelectronic devices. This thesis will address several characteristics involving second harmonic generation and scattering in ZnO nano- and microstructures. A method will be presented for determining the nonlinear coefficients of the second order susceptibility in a single ZnO rod. This method uses transmission geometry where previous methods have employed back-reflected irradiation. The nonlinear coefficients found using this new technique were consistent with previous data from similar structures. Models will be presented for predicting the second harmonic scattering patterns …

Go to article

Oscillator Strength Measurements Of The 5s6s 1s0→5snp 1p1 Rydberg Transitions Of Strontium, S. U. Haq, M. A. Kalyar, M. Rafiq, R. Ali, Naveed K. Piracha, M. A. Baig Apr 2009

Oscillator Strength Measurements Of The 5s6s 1s0→5snp 1p1 Rydberg Transitions Of Strontium, S. U. Haq, M. A. Kalyar, M. Rafiq, R. Ali, Naveed K. Piracha, M. A. Baig

Physics

We report the experimentally determined oscillator strengths for the 5s6s 1S0→5snp 1P1 Rydberg transitions of strontium using two-step excitation in conjunction with a thermionic diode ion detector. The absolute photoionization cross section from the 5s6s 1S0 excited state has been determined by adjusting the polarization vector of the ionizing laser beam parallel, perpendicular, and at the magic angle with respect to that of the exciting dye laser. The measured absolute value of the photoionization cross section 0.9±0.2 Mb at the 5s threshold is used to extract the f values of the 5s6s 1 …

Go to article

Spiral Patterns In Liquid Crystals, Gavin Hartnett Apr 2009

Spiral Patterns In Liquid Crystals, Gavin Hartnett

Renée Crown University Honors Thesis Projects - All

Abstract not Included

Go to article

Characterization Of Microwave Cavity Discharges In A Supersonic Flow, Dareth Janette Drake Apr 2009

Characterization Of Microwave Cavity Discharges In A Supersonic Flow, Dareth Janette Drake

Physics Theses & Dissertations

A partially ionized gas is referred to as either a plasma or a discharge depending on the degree of ionization. The term discharge is usually applied to a weakly ionized gas, i.e. mostly neutrals, where as a plasma usually has a larger degree of ionization. To characterize a discharge the plasma parameters, such as the rotational temperature, vibrational temperature, and electron density, must be determined. Detailed characterization of supersonic flowing discharges is important to many applications in aerospace and aerodynamics. One application is the use of plasma-assisted hydrogen combustion devices to aid in supersonic combustion. In conditions close to the …

Go to article

Theoretical Model Analysis Of Absorption Of A Three Level Diode Pumped Alkali Laser, Charlton D. Lewis Ii Mar 2009

Theoretical Model Analysis Of Absorption Of A Three Level Diode Pumped Alkali Laser, Charlton D. Lewis Ii

Theses and Dissertations

This paper models the absorption phenomena of light in a three level diode pumped alkali laser system. Specifically this model calculates for a user defined set of system parameters the attenuation of the input pump beam and characteristics of the bleached wave. Using Wolfram's Mathematical 6.0 software all necessary physics for an accurate description of absorption was modeled from first principles: energy levels, cross sections, spin-orbit kinetic processes, saturation frequencies, pump attenuation, and differential transmittance, which is a representation of the bleached wave. A specific DPAL scenario was simulated, 455K system temperature, alkali concentration of 6.1 - 1013, …

Go to article

Demonstration And Verification Of A Broad Spectrum Anomalous Dispersion Effects Tool For Index Of Refraction And Optical Turbulence Calculations, J. Jean Cohen Mar 2009

Demonstration And Verification Of A Broad Spectrum Anomalous Dispersion Effects Tool For Index Of Refraction And Optical Turbulence Calculations, J. Jean Cohen

Theses and Dissertations

An atmospheric optical turbulence strength model with a broad wavelength range of 355nm (ultraviolet) to 8.6m (radio frequencies) has been created at AFIT and implemented into the High Energy Laser End-to-End Operational Simulation tool (HELEEOS). This modeling and simulation tool is a first principles atmospheric propagation and characterization model. Within HELEEOS lies the High-Resolution Transmission Molecular Absorption (HITRAN) database, containing 1,734,469 spectral lines for 37 different molecules as of version 12.0 (2004). HITRAN affords HELEEOS incredible accuracy for electromagnetic (EM) propagation prediction. A full understanding of optical turbulence is needed to successfully predict EM radiation propagation, particularly within the application …

Go to article

Analysis And Application Of The Bi-Directional Scatter Distribution Function Of Photonic Crystals, Robert B. Lamott Mar 2009

Analysis And Application Of The Bi-Directional Scatter Distribution Function Of Photonic Crystals, Robert B. Lamott

Theses and Dissertations

Photonic crystals (PCs) are periodic structures built from materials with different refractive indices repeated at sub-wavelength intervals, which results in unusual optical characteristics, including narrowband laser protection, and zero reflectance and high absorption anomalies. Most of the research into the optical properties of PCs has concentrated only on the small range of wavelengths and angles where these effects occur. To better understand where all light leaving a PC is scattered, a Complete Angle Scatter Instrument was used to analyze the scatter from three Guided Mode Resonance Filters designed for laser protection. In the plane of incidence, measurements of the scatter …

Go to article

The Effective Potential Energy Surfaces Of The Nonadiabatic Collision B(2PJA) + H2(1Σ+G,Ν,J) ↔ B(2PJ'A) + H2(1Σ+G,Ν',J'), Matthew B. Garvin Mar 2009

The Effective Potential Energy Surfaces Of The Nonadiabatic Collision B(2PJA) + H2(1Σ+G,Ν,J) ↔ B(2PJ'A) + H2(1Σ+G,Ν',J'), Matthew B. Garvin

Theses and Dissertations

Effective potential energy surfaces (PESs) are calculated for a nonadiabatic collision . This calculation employed 1 2A', 2 2A' and 1 2A" adiabatic PESs numerically calculated at the state-averaged multiconfigurational self-consistent field (SA-MCSCF)/configuration interaction (CI) level for several values of the H2 bond length, H2 orientation angle, and boron distance. The associated nonadiabatic coupling terms (NACTs) were calculated from the SA-MCSCF/CI wave functions using analytic gradient techniques. A line integral through the NACTs was then used to determine the adiabatic-to-diabatic mixing angle required to transform from the 1 2A' and 2 2A' …

Go to article

Separation Of Topographic Features From Magnetic Force Images Using Capacitive Coupling Effect, Byung I. Kim Feb 2009

Separation Of Topographic Features From Magnetic Force Images Using Capacitive Coupling Effect, Byung I. Kim

Physics Faculty Publications and Presentations

Separation of topographic features from magnetic images has been an issue for the past two decades in magnetic force microscopy (MFM). The frequent pickups of the topographic features are interpreted as transitions of the tip between bistable states of the tip-sample assembly in the noncontact and tapping regions. MFM using electrostatic force modulation demonstrates the separation of the topographic features from the magnetic images by removing the tapping state from the bistable states through the introduction of a capacitive coupling.

Go to article

Diffraction Of X-Waves From Multiple Rectangular Slits In An Opaque Screen, Ahmed El Saeed El Halawani Feb 2009

Diffraction Of X-Waves From Multiple Rectangular Slits In An Opaque Screen, Ahmed El Saeed El Halawani

Archived Theses and Dissertations

No abstract provided.

Go to article

Optical Properties And Magnetochromism In Multiferroic Bifeo3, X. S. Xu, T. V. Brinzari, S. Lee, Y. H. Chu, L. W. Martin, A. Kumar, S. Mcgill, R. C. Rai, R. Ramesh, V. Gopalan, S. W. Cheong, J. L. Musfeldt Jan 2009

Optical Properties And Magnetochromism In Multiferroic Bifeo3, X. S. Xu, T. V. Brinzari, S. Lee, Y. H. Chu, L. W. Martin, A. Kumar, S. Mcgill, R. C. Rai, R. Ramesh, V. Gopalan, S. W. Cheong, J. L. Musfeldt

Xiaoshan Xu Papers

In order to investigate spin-charge coupling in multiferroic oxides, we measured the optical properties of BiFeO3. Although the direct 300 K charge gap is observed at 2.67 eV, absorption onset actually occurs at much lower energy with Fe3+ excitations at 1.41 and 1.90 eV. Temperature and magnetic-field-induced spectral changes reveal complex interactions between on-site crystal-field and magnetic excitations in the form of magnon sidebands. We employ the sensitivity of these magnon sidebands to map out the magnetic-fieldtemperature phase diagram which demonstrates optical evidence for spin spiral quenching above 20 T and suggests a spin domain reorientation near …

Go to article

A Review Of Helium Hamiltonians, Carl W. David Jan 2009

A Review Of Helium Hamiltonians, Carl W. David

Chemistry Education Materials

Helium Hamiltonian transformations are discussed in extreme detail.

Go to article

Absence Of Spin Liquid Behavior In Nd3ga5sio14 Using Magneto-Optical Spectroscopy, X. S. Xu, T. V. Brinzari, S. Mcgill, H. D. Zhou, C. R. Wiebe, J. L. Musfeldt Jan 2009

Absence Of Spin Liquid Behavior In Nd3ga5sio14 Using Magneto-Optical Spectroscopy, X. S. Xu, T. V. Brinzari, S. Mcgill, H. D. Zhou, C. R. Wiebe, J. L. Musfeldt

Xiaoshan Xu Papers

We measured the low-lying crystal field levels of Nd3+ in Nd3Ga5SiO14 via magneto-optical spectroscopy and employed the extracted energies, magnetic moments, and symmetries to analyze the magnetic properties and test the spin liquid candidacy of this material. The exchange interaction is surprisingly small, a discovery that places severe constraints on models used to describe the ground state of this system. Further, it demonstrates the value of local-probe photophysical techniques for rare-earthcontaining materials where bulk property measurements can be skewed by low-lying electronic structure.

Go to article

Magnon Sidebands And Spin-Charge Coupling In Bismuth Ferrite Probed By Nonlinear Optical Spectroscopy, M. O. Ramirez, A. Kumar, S. A. Denev, N. J. Podraza, X. S. Xu, R. C. Rai, Y. H. Chu, J. Seidel, L. W. Martin, S. -Y. Yang, E. Saiz, J. F. Ihlefeld, S. Lee, J. Klug, S. W. Cheong, M. J. Bedzyk, O. Auciello, D. G. Schlom, R. Ramesh, J. Orenstein, J. L. Musfeldt, V. Gopalan Jan 2009

Magnon Sidebands And Spin-Charge Coupling In Bismuth Ferrite Probed By Nonlinear Optical Spectroscopy, M. O. Ramirez, A. Kumar, S. A. Denev, N. J. Podraza, X. S. Xu, R. C. Rai, Y. H. Chu, J. Seidel, L. W. Martin, S. -Y. Yang, E. Saiz, J. F. Ihlefeld, S. Lee, J. Klug, S. W. Cheong, M. J. Bedzyk, O. Auciello, D. G. Schlom, R. Ramesh, J. Orenstein, J. L. Musfeldt, V. Gopalan

Xiaoshan Xu Papers

The interplay between spin waves (magnons) and electronic structure in materials leads to the creation of additional bands associated with electronic energy levels which are called magnon sidebands. The large difference in the energy scales between magnons (meV) and electronic levels (eV) makes this direct interaction weak and hence makes magnon sidebands difficult to probe. Linear light absorption and scattering techniques at low temperatures are traditionally used to probe these sidebands. Here we show that optical secondharmonic generation, as the lowest-order nonlinear process, can successfully probe the magnon sidebands at room temperature and up to 723 K in bismuth ferrite, …

Go to article

Synthesis And Characterization Of Homoleptic And Heteroleptic Ruthenium Polypyridine Complexes, Anwar A. Bhuiyan, S. Kudo, C. Wade, R. F. Davis Jan 2009

Synthesis And Characterization Of Homoleptic And Heteroleptic Ruthenium Polypyridine Complexes, Anwar A. Bhuiyan, S. Kudo, C. Wade, R. F. Davis

Journal of the Arkansas Academy of Science

The homoleptic ruthenium(II) complex Ru(C13H10N2)3(PF6)2, and heteroleptic ruthenium(II) complexes Ru(C13H10N2)2(C10H8N2)(PF6)2, and Ru(C13H10N2)(C10H8N2)2(PF6)2 have been prepared by following the standard synthetic procedure. These complexes were then purified by repeated column chromatography. The identity and the integrity of the complexes were confirmed by elemental analysis and mass spectroscopy. The calculated and the experimental values for the elemental analysis were in good agreement. The calculated and the experimental molar masses obtained were also identical. Ultravioletvisible absorption and emission spectroscopic methods were used to investigate the properties of these complexes. The absorption spectra of all complexes consist of a series of absorption bands in …

Go to article

Next Last