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Atomic, Molecular and Optical Physics Commons™
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Articles 1 - 24 of 24
Full-Text Articles in Atomic, Molecular and Optical Physics
Fabrication Of Robust Superconducting Granular Aluminium/Palladium Bilayer Microbolometers With Sub-Nanosecond Response, Thomas E. Wilson
Fabrication Of Robust Superconducting Granular Aluminium/Palladium Bilayer Microbolometers With Sub-Nanosecond Response, Thomas E. Wilson
Physics Faculty Research
We provide a convenient recipe for fabricating reliable superconducting microbolometers as acoustic phonon detectors with sub-nanosecond response, using imagereversal optical lithography and dc-magnetron sputtering, and our recipe requires no chemical or plasma etching. Our approach solves the traditional problem for granular aluminium bolometers of unreliable (i.e., non-Ohmic) electrical contacts by sequentially sputtering the granular aluminium film and then a palladium capping layer. We use dc calibration data, the method of Danilchenko et al. [1], and direct nanosecond-pulsed photoexcitation to obtain the microbolometer’s characteristic current, thermal conductance, characteristic relaxation time, and heat capacity. We also demonstrate the use of the deconvolution …
Decomposition-Based Recovery Of Absorbers In Turbid Media, S D. Campbell, I L. Goodin, S D. Grobe, Qichang Su, Rainer Grobe
Decomposition-Based Recovery Of Absorbers In Turbid Media, S D. Campbell, I L. Goodin, S D. Grobe, Qichang Su, Rainer Grobe
Faculty publications – Physics
We suggest that the concept of the point-spread function traditionally used to predict the blurred image pattern of various light sources embedded inside turbid media can be generalized under certain conditions to predict also the presence and location of spatially localized absorbing inhomogeneities based on shadow point-spread functions associated with each localized absorber in the medium. The combined image obtained from several absorbers can then be decomposed approximately into the arithmetic sums of these individual shadow point-spread functions with suitable weights that can be obtained from multiple-regression analysis. This technique permits the reconstruction of the location of absorbers.
Practical Sensor For Measurement Of Nitrogen, Dusan Popovic, Vladimir Milosavljevic, Steven Daniels
Practical Sensor For Measurement Of Nitrogen, Dusan Popovic, Vladimir Milosavljevic, Steven Daniels
Articles
This paper presents a method for precise measurement of atomic and molecular nitrogen in an oxygen-nitrogen dc plasma. This is achieved by monitoring the intensities of the atomic nitrogen spectral line at 821.6 nm and the molecular nitrogen bandhead at 337.1 nm, relative to the atomic oxygen spectral line at 844.7 nm. Oxygen is one of the most frequently used gases for surface chemical treatment, including deposition and etching, therefore the ability to measure and control the process and chemical composition of the process is essential. To validate this oxygen actimometry method for N2-xO2 (where x varies from 0 to …
Higher-Order Threshold Corrections For Single Top Quark Production, Nikolaos Kidonakis
Higher-Order Threshold Corrections For Single Top Quark Production, Nikolaos Kidonakis
Faculty Articles
I discuss single top quark production at the Tevatron and the LHC. The cross section, including soft-gluon threshold corrections through NNNLO, is presented for each partonic channel. The higher-order corrections provide significant contributions to the single top cross sections at both colliders.
Classical-Quantum Correspondence In Electron-Positron Pair Creation, N I. Chott, Qichang Su, Rainer Grobe
Classical-Quantum Correspondence In Electron-Positron Pair Creation, N I. Chott, Qichang Su, Rainer Grobe
Faculty publications – Physics
We examine the creation of electron-positron pairs in a very strong force field. Using numerical solutions to quantum field theory we calculate the spatial and momentum probability distributions for the created particles. A comparison with classical mechanical phase space calculations suggests that despite the fully relativistic and quantum mechanical nature of the matter creation process, most aspects can be reproduced accurately in terms of classical mechanics.
Optical Absorption, Depolarization, And Scatter Of Epitaxial Single-Crystal Chemical-Vapor-Deposited Diamond At 1.064 Μm, Giorgio Turri, Ying Chen, Michael Bass
Optical Absorption, Depolarization, And Scatter Of Epitaxial Single-Crystal Chemical-Vapor-Deposited Diamond At 1.064 Μm, Giorgio Turri, Ying Chen, Michael Bass
Publications
No abstract provided.
Optical Properties Of Epitaxial Single-Crystal Chemical-Vapor-Deposited Diamond, Giorgio Turri, Ying Chen, Michael Bass, David Orchard, James E. Butler
Optical Properties Of Epitaxial Single-Crystal Chemical-Vapor-Deposited Diamond, Giorgio Turri, Ying Chen, Michael Bass, David Orchard, James E. Butler
Publications
Epitaxial single-crystal chemical-vapor-deposited diamond was obtained from Element Six Ltd. (Ascot, UK) and from Apollo Diamond (Boston, MA). Both companies provided 5 x 5 mm squares with thicknesses ranging from 0.5 to 1.5 mm. In addition, Element Six provided 10-mm-diameter disks with a thickness of 1.0 mm. The absorptance of all specimens at 1064 nm was measured by laser calorimetry, with good agreement between independent measurements at the University of Central Florida and at QinetiQ (Malvern, UK). Depolarization at 1064 nm and ultraviolet absorption properties are also reported.
Velocity Half-Sphere Model For Multiple Scattering In A Semi-Infinite Medium, S Menon, Q Su, Rainer Grobe
Velocity Half-Sphere Model For Multiple Scattering In A Semi-Infinite Medium, S Menon, Q Su, Rainer Grobe
Faculty publications – Physics
We show how the velocity half-sphere model [S. Menon, Q. Su, and R. Grobe, Phys. Rev. E 72, 041910 (2005)] recently introduced to predict the propagation of light for an infinite turbid medium can be extended to account for the emission of multiply scattered light for a geometry with a planar boundary. A comparison with exact solutions obtained from Monte Carlo simulations suggests that this approach can improve the predictions of the usual diffusion theory for both isotropic and highly forward scattering media with reflecting interfaces.
Higher-Order Soft Gluon Corrections In Single Top Quark Production At The Cern Lhc, Nikolaos Kidonakis
Higher-Order Soft Gluon Corrections In Single Top Quark Production At The Cern Lhc, Nikolaos Kidonakis
Faculty Articles
I present a calculation of soft-gluon corrections to single top-quark production in pp collisions at the LHC via the standard model partonic processes in the t and s channels and associated top quark and W boson production. Higher-order soft-gluon corrections through next-to-next-to-next-to-leading order (NNNLO) are calculated at next-to-leading logarithmic (NLL) accuracy. The soft-gluon corrections in the s channel and in tW production are large and dominant, while in the t channel they are not a good approximation of the complete QCD corrections.
Nonlocal Entanglement Of Coherent States, Complementarity, And Quantum Erasure, Christopher C. Gerry, Rainer Grobe
Nonlocal Entanglement Of Coherent States, Complementarity, And Quantum Erasure, Christopher C. Gerry, Rainer Grobe
Faculty publications – Physics
We describe a nonlocal method for generating entangled coherent states of a two-mode field wherein the field modes never meet. The proposed method is an extension of an earlier proposal [C. C. Gerry, Phys. Rev. A 59, 4095 (1999)] for the generation of superpositions of coherent states. A single photon injected into a Mach-Zehnder interferometer with cross-Kerr media in both arms coupling with two external fields in coherent states produces entangled coherent states upon detection at one of the output ports. We point out that our proposal can be alternatively viewed as a "which path" experiment, and in the case …
Ground State Structures And Photoelectron Spectroscopy Of [Com(Coronene)]− Complexes, Anil K. Kandalam, Boggavarapu Kiran, Puru Jena, Xiang Li, Andrej Grubisic, Kit H. Bowen
Ground State Structures And Photoelectron Spectroscopy Of [Com(Coronene)]− Complexes, Anil K. Kandalam, Boggavarapu Kiran, Puru Jena, Xiang Li, Andrej Grubisic, Kit H. Bowen
Physics & Engineering Faculty Publications
No abstract provided.
Focusing Capillary Optics For Use In Solution Small-Angle X-Ray Scattering, Jessica S. Lamb, Sterling Cornaby, Kurt Andresen, Lisa W. Kwok, Hye Yoon Park, Xiangyun Qiu, Detlef-M. Smilgies, Donald H. Bilderback, Lois Pollack
Focusing Capillary Optics For Use In Solution Small-Angle X-Ray Scattering, Jessica S. Lamb, Sterling Cornaby, Kurt Andresen, Lisa W. Kwok, Hye Yoon Park, Xiangyun Qiu, Detlef-M. Smilgies, Donald H. Bilderback, Lois Pollack
Physics and Astronomy Faculty Publications
Measurements of the global conformation of macromolecules can be carried out using small-angle X-ray scattering (SAXS). Glass focusing capillaries, manufactured at the Cornell High Energy Synchrotron Source (CHESS), have been successfully employed for SAXS measurements on the heme protein cytochrome c. These capillaries provide high X-ray flux into a spot size of tens of micrometres, permitting short exposures of small-volume samples. Such a capability is ideal for use in conjunction with microfluidic mixers, where time resolution may be determined by beam size and sample volumes are kept small to facilitate mixing and conserve material.
Low-Energy Electron Capture By 6-Aza-2-Thiothymine: Investigations By Electron Attachment And Electron Transmission Spectroscopies, Stanislav A. Pshenichnyuk, Gordon A. Gallup, Paul Burrow
Low-Energy Electron Capture By 6-Aza-2-Thiothymine: Investigations By Electron Attachment And Electron Transmission Spectroscopies, Stanislav A. Pshenichnyuk, Gordon A. Gallup, Paul Burrow
Paul Burrow Publications
The interaction of low-energy (0-10 eV) electrons with 6-aza-2-thiothymine is investigated in the gas phase by studies of sharp structure in the total electron scattering cross section and by mass analysis of the stable or long-lived negative ions produced by electron attachment. The most efficient fragmentation process, occurring at 0.15 eV, involves the ejection of a closed-shell neutral molecule (CH3CN). Ab initio calculations support our proposal that this process leads to ring closure to form a stable four-member heterocyclic anion. A long-lived parent anion with an approximate lifetime of 75 microseconds is observed near zero electron energy, and …
Anisotropic Magnetoresistance In Colossal Magnetoresistive La1−Xsrxmno3 Thin Films, Jeng-Bang Yau, X. Hong, A. Posadas, C. H. Ahn, W. Gao, E. Altman, Y. Bason, L. Klein, M. Sidorov, Z. Krivokapic
Anisotropic Magnetoresistance In Colossal Magnetoresistive La1−Xsrxmno3 Thin Films, Jeng-Bang Yau, X. Hong, A. Posadas, C. H. Ahn, W. Gao, E. Altman, Y. Bason, L. Klein, M. Sidorov, Z. Krivokapic
Xia Hong Publications
We report on magnetic field and temperature-dependent measurements of the anisotropic magnetoresistance (AMR) in epitaxial La1−xSrxMnO3 (LSMO) thin films. While in 3d ferromagnetic alloys increasing the magnetization, either by reducing the temperature or increasing the magnetic field, increases the AMR, we find that in LSMO films the AMR dependence on magnetization displays nonmonotonic behavior which becomes particularly pronounced in lightly doped compounds. We believe that this behavior is related to the inhomogeneity exhibited by these materials.
Planar Hall Effect In Epitaxial Thin Films Of Magnetite, Y. Bason, L. Klein, H. Q. Wang, J. Hoffman, X. Hong, V. E. Henrich, C. H. Ahn
Planar Hall Effect In Epitaxial Thin Films Of Magnetite, Y. Bason, L. Klein, H. Q. Wang, J. Hoffman, X. Hong, V. E. Henrich, C. H. Ahn
Xia Hong Publications
We measured the planar Hall effect (PHE) of magnetite (Fe3O4) films between 150 and 350 K. The PHE was measured both with a constant magnetic field rotating in the plane of the sample and in a remanent state after applying a field in specific directions. The PHE amplitude decreases with temperature; however, it changes little between 300 and 350 K. The remanent PHE signal is as high as 10 V/A, larger than previously observed in manganite films. We also measured the PHE in the remanent state and found that its magnitude and stability make it a …
A Relation Between Energies Of The Short-Lived Negative Ion States And Energies Of Unfilled Molecular Orbitals For A Series Of Bromoalkanes, S. A. Pshenichnyuk, N. L. Asfandiarov, Paul Burrow
A Relation Between Energies Of The Short-Lived Negative Ion States And Energies Of Unfilled Molecular Orbitals For A Series Of Bromoalkanes, S. A. Pshenichnyuk, N. L. Asfandiarov, Paul Burrow
Paul Burrow Publications
A series of bromoalkanes was investigated by means of electron transmission spectroscopy in the gas phase. Experimental values of vertical electron affinities associated with occupation of the LUMO by an incoming electron were assigned using ab initio quantum chemical calculations. The predicted vertical electron affinity values differ from measured ones by at most ±0.2 eV.
Magnetic Enhancement In Cobalt-Manganese Alloy Clusters, Shuangye Yin, Ramiro Moro, Xiaoshan Xu, Walter A. De Heer
Magnetic Enhancement In Cobalt-Manganese Alloy Clusters, Shuangye Yin, Ramiro Moro, Xiaoshan Xu, Walter A. De Heer
Xiaoshan Xu Papers
Magnetic moments of CoNMnM and CoNVM clusters (N ≤ 60; M ≤ N/3) are measured in molecular beams using the Stern-Gerlach deflection method. Surprisingly, the per atom average moments of CoNMnM clusters are found to increase with Mn concentration, in contrast to bulk CoMn. The enhancement with Mn doping is found to be independent of cluster size and composition in the size range studied. Meanwhile, CoNVM clusters show reduction of average moments with increasing V doping, consistent with what is expected in bulk CoV. The results are …
Unitary And Nonunitary Approaches In Quantum Field Theory, K D. Lamb, Christopher C. Gerry, Rainer Grobe
Unitary And Nonunitary Approaches In Quantum Field Theory, K D. Lamb, Christopher C. Gerry, Rainer Grobe
Faculty publications – Physics
We use a simplified essential state model to compare two quantum field theoretical approaches to study the creation of electron-positron pairs from the vacuum. In the unitary approach the system is characterized by a state with different numbers of particles that is described by occupation numbers and evolves with conserved norm. The nonunitary approach can predict the evolution of wave functions and density operators with a fixed number of particles but time-dependent norms. As an example to illustrate the differences between both approaches, we examine the degree of entanglement for the Klein paradox, which describes the creation of an electron-positron …
Temperature-Driven Transition From The Wigner Crystal To The Bond-Charge-Density Wave In The Quasi-One-Dimensional Quarter-Filled Band, R. T. Clay, Rahul Hardikar, S. Mazumdar
Temperature-Driven Transition From The Wigner Crystal To The Bond-Charge-Density Wave In The Quasi-One-Dimensional Quarter-Filled Band, R. T. Clay, Rahul Hardikar, S. Mazumdar
Scholarship and Professional Work - LAS
It is known that within the interacting electron model Hamiltonian for the one-dimensional 1/4-filled band, the singlet ground state is a Wigner crystal only if the nearest-neighbor electron-electron repulsion is larger than a critical value. We show that this critical nearest-neighbor Coulomb interaction is different for each spin subspace, with the critical value decreasing with increasing spin. As a consequence, with the lowering of temperature, there can occur a transition from a Wigner crystal charge-ordered state to a spin-Peierls state that is a bond-charge-density wave with charge occupancies different from the Wigner crystal. This transition is possible because spin excitations …
Phase Diagram Of The One-Dimensional Hubbard-Holstein Model At Half And Quarter Filling, Rahul Hardikar, R. T. Clay
Phase Diagram Of The One-Dimensional Hubbard-Holstein Model At Half And Quarter Filling, Rahul Hardikar, R. T. Clay
Scholarship and Professional Work - LAS
The Hubbard-Holstein model is one of the simplest to incorporate both electron-electron and electron-phonon interactions. In one dimension at half filling, the Holstein electron-phonon coupling promotes on-site pairs of electrons and a Peierls charge-density wave, while the Hubbard on-site Coulomb repulsion U promotes antiferromagnetic correlations and a Mott insulating state. Recent numerical studies have found a possible third intermediate phase between Peierls and Mott states. From direct calculations of charge and spin susceptibilities, we show that (i) as the electron-phonon coupling is increased, first a spin gap opens, followed by the Peierls transition. Between these two transitions, the metallic intermediate …
Formation Of In- (2×1) And In Islands On Si (100) - (2×1) By Femtosecond Pulsed Laser Deposition, M. A. Hafez, H. E. Elsayed-Ali
Formation Of In- (2×1) And In Islands On Si (100) - (2×1) By Femtosecond Pulsed Laser Deposition, M. A. Hafez, H. E. Elsayed-Ali
Electrical & Computer Engineering Faculty Publications
The growth of indium on a vicinal Si (100) - (2×1) surface at room temperature by femtosecond pulsed laser deposition (fsPLD) was investigated by in situ reflection high-energy electron diffraction (RHEED). Recovery of the RHEED intensity was observed between laser pulses and when the growth was terminated. The surface diffusion coefficient of deposited In on initial two-dimensional (2D) In- (2×1) layer was determined. As growth proceeds, three-dimensional In islands grew on the 2D In- (2×1) layer. The RHEED specular profile was analyzed during film growth, while the grown In islands were examined by ex situ atomic force microscopy. The full …
Design And Performance Of A Curved-Crystal X-Ray Emission Spectrometer, A. C. Hudson, Wayne C. Stolte, Dennis W. Lindle, Renaud Guillemin
Design And Performance Of A Curved-Crystal X-Ray Emission Spectrometer, A. C. Hudson, Wayne C. Stolte, Dennis W. Lindle, Renaud Guillemin
Chemistry and Biochemistry Faculty Research
A curved-crystal x-ray emission spectrometer has been designed and built to measure 2–5 keV x-ray fluorescence resulting from a core-level excitation of gas phase species. The spectrometer can rotate 180°, allowing detection of emitted x rays with variable polarization angles, and is capable of collecting spectra over a wide energy range (20 eV wide with 0.5 eV resolution at the Cl K edge) simultaneously. In addition, the entire experimental chamber can be rotated about the incident-radiation axis by nearly 360° while maintaining vacuum, permitting measurements of angular distributions of emitted x rays.
Experimental Study Of Exclusive ²H(E,E'P)N Reaction Mechanisms At High Q², S. E. Kuhn, M. J. Amaryan, H. Bagdasaryan, M. Bektasoglu, S. L. Careccia, K. V. Dharmawardane, G. E. Dodge, N. Guler, C. E. Hyde-Wright, H. G. Juengst, N. Kalantarians, A. Klein, M. R. Niroula, R. A. Niyazov, S. Tkachenko, L. B. Weinstein, J. Zhang, Et. Al., Clas Collaboration
Experimental Study Of Exclusive ²H(E,E'P)N Reaction Mechanisms At High Q², S. E. Kuhn, M. J. Amaryan, H. Bagdasaryan, M. Bektasoglu, S. L. Careccia, K. V. Dharmawardane, G. E. Dodge, N. Guler, C. E. Hyde-Wright, H. G. Juengst, N. Kalantarians, A. Klein, M. R. Niroula, R. A. Niyazov, S. Tkachenko, L. B. Weinstein, J. Zhang, Et. Al., Clas Collaboration
Physics Faculty Publications
The reaction 2H(e,e(')p)n has been studied with full kinematic coverage for photon virtuality 1.75 < Q2< 5.5 GeV2. Comparisons of experimental data with theory indicate that for very low values of neutron recoil momentum (pn< 100 MeV/c) the neutron is primarily a spectator and the reaction can be described by the plane-wave impulse approximation. For 100 < pn< 750 MeV/c, proton-neutron rescattering dominates the cross section, while Delta production followed by the NΔ → NN transition is the primary contribution at higher momenta.
Diffusion And Fractional Diffusion Based Models For Multiple Light Scattering And Image Analysis, Jonathan Blackledge
Diffusion And Fractional Diffusion Based Models For Multiple Light Scattering And Image Analysis, Jonathan Blackledge
Articles
This paper considers a fractional light diffusion model as an approach to characterizing the case when intermediate scattering processes are present, i.e. the scattering regime is neither strong nor weak. In order to introduce the basis for this approach, we revisit the elements of formal scattering theory and the classical diffusion problem in terms of solutions to the inhomogeneous wave and diffusion equations respectively. We then address the significance of these equations in terms of a random walk model for multiple scattering. This leads to the proposition of a fractional diffusion equation for modelling intermediate strength scattering that is based …