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Articles 1  20 of 20
FullText Articles in Physical Sciences and Mathematics
Binary Condensation In A Supersonic Nozzle, Barbara Ellen Wyslouzil, Christopher H. Heath, Janice L. Cheung, Gerald Wilemski
Binary Condensation In A Supersonic Nozzle, Barbara Ellen Wyslouzil, Christopher H. Heath, Janice L. Cheung, Gerald Wilemski
Physics Faculty Research & Creative Works
We present data from the first systematic studies of binary condensation in supersonic nozzles. The apparatus used to conduct the experiments is described in detail, and the important issues of stability and reproducibility of the experiments are discussed. Experiments were conducted with water, ethanol, propanol, and binary mixtures of these compounds. Onset was determined in the temperature range of 190215 K, and for each mixture composition the pressures of the condensible species at an onset temperature of 207 K were determined. For the ideal ethanolpropanol mixtures, the onset pressures at constant temperature vary almost linearly between those of the pure ...
Transport Anomalies And Marginal FermiLiquid Effects At A Quantum Critical Point, Dietrich Belitz, Theodore R. Kirkpatrick, Rajesh S. Narayanan, Thomas Vojta
Transport Anomalies And Marginal FermiLiquid Effects At A Quantum Critical Point, Dietrich Belitz, Theodore R. Kirkpatrick, Rajesh S. Narayanan, Thomas Vojta
Physics Faculty Research & Creative Works
The conductivity and the tunneling density of states of disordered itinerant electrons in the vicinity of a ferromagnetic transition at low temperature are discussed. Critical fluctuations lead to nonanalytic frequency and temperature dependencies that are distinct from the usual longtime tail effects in a disordered Fermi liquid. The crossover between these two types of behavior is proposed as an experimental check of recent theories of the quantum ferromagnetic critical behavior. In addition, the quasiparticle properties at criticality are shown to be those of a marginal Fermi liquid.
Ionization Of Hydrogen Atoms By Fast Electrons, Sindu P. Jones, Don H. Madison
Ionization Of Hydrogen Atoms By Fast Electrons, Sindu P. Jones, Don H. Madison
Physics Faculty Research & Creative Works
We study ionization of atomic hydrogen by fast electrons using asymptotically correct twocenter wave functions to describe the scattering system both initially and finally. For the final state, we employ the wellknown product wave function of Redmond, which treats all three twobody Coulomb interactions exactly, albeit independently. This "3C" wave function is the leading term of the exact scattering wave function, regardless of how slow the three particles are, if any two particles have large relative separation [Y.E. Kim and A.L. Zubarev, Phys. Rev. A 56, 521 (1997)]. Here we extend the analysis of Qiu et al. [Phys ...
Resummation Of Nonalternating Divergent Perturbative Expansions, Ulrich D. Jentschura
Resummation Of Nonalternating Divergent Perturbative Expansions, Ulrich D. Jentschura
Physics Faculty Research & Creative Works
A method for the resummation of a nonalternating divergent perturbation series is described. The procedure constitutes a generalization of the BorelPadã method. Of crucial importance is a special integration contour in the complex plane. Nonperturbative imaginary contributions can be inferred from the purely real perturbative coefficients. A connection is drawn from the quantum field theoretic problem of resummation to divergent perturbative expansions in other areas of physics.
Concept Of Local Polaritons And Optical Properties Of Mixed Polar Crystals, Lev I. Deych, Alexey Yamilov, Alexander A. Lisyansky
Concept Of Local Polaritons And Optical Properties Of Mixed Polar Crystals, Lev I. Deych, Alexey Yamilov, Alexander A. Lisyansky
Physics Faculty Research & Creative Works
The concept of local polaritons is used to describe the optical properties of mixed crystals in the frequency region of their restrahlen band. It is shown that this concept allows for a physically transparent explanation of the presence of weak features in the spectra of socalled onemode crystals and for onetwo mode behavior. The previous models Were able to explain these features only with the use of many fitting parameters. We show that under certain Conditions new impurityinduced polariton modes may arise within the restrahlen of the host crystals, and study their dispersion laws and density of states. Particularly, we ...
Resummation Of Qed Perturbation Series By Sequence Transformations And The Prediction Of Perturbative Coefficients, Ulrich D. Jentschura, Jens Becher, Ernst Joachim Weniger, Gerhard Soff
Resummation Of Qed Perturbation Series By Sequence Transformations And The Prediction Of Perturbative Coefficients, Ulrich D. Jentschura, Jens Becher, Ernst Joachim Weniger, Gerhard Soff
Physics Faculty Research & Creative Works
We propose a method for the resummation of divergent perturbative expansions in quantum electrodynamics and related field theories. The method is based on a nonlinear sequence transformation and uses as input data only the numerical values of a finite number of perturbative coefficients. The results obtained in this way are for alternating series superior to those obtained using Padé approximants. The nonlinear sequence transformation fulfills an accuracythroughorder relation and can be used to predict perturbative coefficients. In many cases, these predictions are closer to available analytic results than predictions obtained using the Padé method.
ShortPulse LaserInduced Stabilization Of Autoionizing States, Heider N. Ereifej, J. Greg Story
ShortPulse LaserInduced Stabilization Of Autoionizing States, Heider N. Ereifej, J. Greg Story
Physics Faculty Research & Creative Works
Atoms in doubly excited states above the first ionization limit can decay via autoionization in which an electron is emitted leaving an ion, or by photoemission which leaves the atom in a singly excited state. In this paper, it is demonstrated that interaction between the atoms and a laser pulse that is short compared to the autoionization lifetime can lead to large enhancement of the photoemission process by stimulating the atoms to emit a photon. Since the resultant singly excited atoms do not autoionize, this process can be viewed as an enhancement of the stabilization of the doubly excited atoms ...
Observation Of Stratospheric Ozone Depletion Associated With Delta Ii Rocket Emissions, Martin N. Ross, Darin W. Toohey, W. T. Rawlins, E. C. Richard, K. K. Kelly, A. F. Tuck, M. H. Proffitt, Donald E. Hagen, Alfred R. Hopkins, Philip D. Whitefield, J. R. Benbrook, W. R. Sheldon
Observation Of Stratospheric Ozone Depletion Associated With Delta Ii Rocket Emissions, Martin N. Ross, Darin W. Toohey, W. T. Rawlins, E. C. Richard, K. K. Kelly, A. F. Tuck, M. H. Proffitt, Donald E. Hagen, Alfred R. Hopkins, Philip D. Whitefield, J. R. Benbrook, W. R. Sheldon
Physics Faculty Research & Creative Works
Ozone, chlorine monoxide, methane, and submicron particulate concentrations were measured in the stratospheric plume wake of a Delta II rocket powered by a combination of solid (NH_{4}ClO_{4}/Al) and liquid (LOX/kerosene) propulsion systems. We apply a simple kinetics model describing the main features of gasphase chlorine reactions in solid propellant exhaust plumes to derive the abundance of total reactive chlorine in the plume and estimate the associated cumulative ozone loss. Measured ozone loss during two plume encounters (12 and 39 minutes after launch) exceeded the estimate by about a factor of about two. Insofar as only ...
Direct Measurement Of Oscillations Between Degenerate TwoElectron BoundState Configurations In A Rapidly Autoionizing System, Heider N. Ereifej, J. Greg Story
Direct Measurement Of Oscillations Between Degenerate TwoElectron BoundState Configurations In A Rapidly Autoionizing System, Heider N. Ereifej, J. Greg Story
Physics Faculty Research & Creative Works
In this paper we report a direct observation of the oscillation between boundstate configurations in a rapidly autoionizing system. Calcium atoms were excited to a pure 4p_{3/2}nd twoelectron configuration using a 500fsec laser pulse. The initial 4p_{3/2}nd doubly excited state is energy degenerate with the 4p_{1/2}n'd states and several continuum channels. Because of the shortpulse excitation, the initial state of the atom is not an energy eigenstate, but a nonstationary wave packet. As a result, oscillations between the two bound configurations were produced. These oscillations were measured by scanning the ...
Annealed Disorder, Rare Regions, And Local Moments: A Novel Mechanism For MetalInsulator Transitions, Dietrich Belitz, Theodore R. Kirkpatrick, Thomas Vojta
Annealed Disorder, Rare Regions, And Local Moments: A Novel Mechanism For MetalInsulator Transitions, Dietrich Belitz, Theodore R. Kirkpatrick, Thomas Vojta
Physics Faculty Research & Creative Works
It is shown that, for noninteracting electron systems, annealed magnetic disorder leads to a new mechanism, and a new universality class, for a metalinsulator transition. The transition is driven by a vanishing of the thermodynamic density susceptibility rather than by localization effects. The critical behavior in d = 2 + ∈ dimensions is determined, and the underlying physics is discussed. It is further argued that annealed magnetic disorder, in addition to underlying quenched disorder, describes local magnetic moments in electronic systems.
Genuine Saddle Point And Nucleation Potential For Binary Systems, Jinsong Li, Igor L. Maksimov, Gerald Wilemski
Genuine Saddle Point And Nucleation Potential For Binary Systems, Jinsong Li, Igor L. Maksimov, Gerald Wilemski
Physics Faculty Research & Creative Works
A generalized nucleation potential is constructed for binary systems. The potential consists of the reversible work of cluster formation plus additional terms arising from various kinetic effects. We show that the major nucleation flux passes through the saddle point (termed the genuine saddle point) of this generalized nucleation potential. The generalized nucleation potential reduces to the kinetic potential of a unary system when one component vanishes. The genuine saddle point concept provides a convenient way to identify systems and conditions for which the ridge crossing phenomenon occurs. Our theory agrees approximately with exact numerical results.
Photoelectron Diffraction Determination Of The Structure Of Ultrathin Vanadium Films On Cu(001), George Daniel Waddill, D. P. Moore, Osman Ozturk
Photoelectron Diffraction Determination Of The Structure Of Ultrathin Vanadium Films On Cu(001), George Daniel Waddill, D. P. Moore, Osman Ozturk
Physics Faculty Research & Creative Works
Xray photoelectron diffraction (XPD) and lowenergy electron diffraction (LEED) have been used to study the structural properties of V thin films on Cu(001). For roomtemperature growth, submonolayer coverages result in (1x1) LEED patterns that evolve to exhibit very diffuse (2x1) structure at approximately 1 monolayer coverage. We do not observe any V forwardfocusing enhancements for V films that exhibit either the (1x1) or (2x1) structure, suggesting that these structures are limited to the first 12 vanadium layers. At coverages above 1 monolayer, the V films display complex LEED patterns characteristic of four bcc(110) domains. This structure persists to ...
Quantum Gravity Corrections To The Schwarzschild Mass, Marco Cavaglia, Carlo Ungarelli
Quantum Gravity Corrections To The Schwarzschild Mass, Marco Cavaglia, Carlo Ungarelli
Physics Faculty Research & Creative Works
Vacuum spherically symmetric Einstein gravity in (N≥4) dimensions can be cast in a twodimensional conformal nonlinear sigma model form by first integrating on the (N  2)dimensional (hyper)sphere and then performing a canonical transformation. The conformal sigma model is described by two fields which are related to the ArnowittDeserMisner (ADM) mass and to the radius of the (N  2)dimensional (hyper)sphere, respectively. By quantizing perturbatively the theory we estimate the quantum corrections to the ADM mass of a black hole.
Excitation Of Ar 3p⁵4s3p⁵4p Transitions By Electron Impact, Colette M. Maloney, Jerry Peacher, Klaus Bartschat, Don H. Madison
Excitation Of Ar 3p⁵4s3p⁵4p Transitions By Electron Impact, Colette M. Maloney, Jerry Peacher, Klaus Bartschat, Don H. Madison
Physics Faculty Research & Creative Works
Electronimpact excitation of argon from the 3p^{5}4s (J=0,2) metastable states to the 3p^{5}4p (J=0,1,2,3) manifold has been investigated in the semirelativistic firstorder distortedwave and planewave Born approximations. The results are compared with recent experimental data of Boffard et al. [Phys. Rev. A 59, 2749 (1999)] and Rmatrix predictions by Bartschat and Zeman [Phys. Rev. A 59, R2552 (1999)]. In cases for which perturbative approaches are expected to be valid, the planewave Born approximation is found to be sufficiently accurate and thus allows for an efficient calculation of results over a ...
Correlated ThreeElectron Continuum States In Triple Ionization By Fast HeavyIon Impact, Michael Schulz, Robert Moshammer, Wayne M. Schmitt, Holger Kollmus, Rido Mann, Siegbert Hagmann, Ronald E. Olson, Joachim Hermann Ullrich
Correlated ThreeElectron Continuum States In Triple Ionization By Fast HeavyIon Impact, Michael Schulz, Robert Moshammer, Wayne M. Schmitt, Holger Kollmus, Rido Mann, Siegbert Hagmann, Ronald E. Olson, Joachim Hermann Ullrich
Physics Faculty Research & Creative Works
We have performed a kinematically complete experiment for triple ionization in atomic collisions. Data were obtained for 3.6MeV/amu Au^{53+} impact on Ne. A specific Dalitz representation was developed allowing one to plot in a single spectrum the energy of all three ionized electrons and, simultaneously, obtain information on their emission angles with respect to the projectile direction. The data show distinct fragmentation patterns favoring very asymmetric energy partitionings with one fast and two slow electrons. They are compared to various Classical Trajectory Monte Carlo (CTMC) models. The experimental results are well described only if the electronelectron interaction ...
Observations Of Particulates Within The North Atlantic Flight Corridor: Polinat 2, SeptemberOctober 1997, J. D. Paladino, Donald E. Hagen, Philip D. Whitefield, Alfred Raymond Hopkins, Otmar Schmid, M. R. Wilson, Hans Schlager, Peter Schulte
Observations Of Particulates Within The North Atlantic Flight Corridor: Polinat 2, SeptemberOctober 1997, J. D. Paladino, Donald E. Hagen, Philip D. Whitefield, Alfred Raymond Hopkins, Otmar Schmid, M. R. Wilson, Hans Schlager, Peter Schulte
Physics Faculty Research & Creative Works
This paper discusses particulate concentration and size distribution data gathered using the University of MissouriRolla Mobile Aerosol Sampling System (UMRMASS), and used to investigate the southern extent of the eastern end of the North Atlantic Flight Corridor (NAFC) during project Pollution From Aircraft Emissions in the North Atlantic Flight Corridor/Subsonic Assessment (SASS) Ozone and Nitrogen Oxide Experiment (POLINAT 2/SONEX) from September 19 to October 23, 1997. The analysis presented in this paper focuses on "the corridor effect," or enhancement of pollutants by jet aircraft combustion events. To investigate the phenomena, both vertical and horizontal profiles of the corridor ...
The Effects Of Substituting Iron For Manganese In Smmn₆Ge₆: Magnetic And Crystallographic Properties, J. Han, William B. Yelon, Naushad Ali, I. Dubenko, G. K. Marasinghe, Ph. I'Héritier, William Joseph James
The Effects Of Substituting Iron For Manganese In Smmn₆Ge₆: Magnetic And Crystallographic Properties, J. Han, William B. Yelon, Naushad Ali, I. Dubenko, G. K. Marasinghe, Ph. I'Héritier, William Joseph James
Physics Faculty Research & Creative Works
No abstract provided.
Crystal And Magnetic Structures Of Lani₅₋ₓMnₓ, ChiuYing Tai, G. K. Marasinghe, Oran Allan Pringle, William Joseph James, Muguo Chen, William B. Yelon, I. Dubenko, Naushad Ali, Ph. I'Héritier
Crystal And Magnetic Structures Of Lani₅₋ₓMnₓ, ChiuYing Tai, G. K. Marasinghe, Oran Allan Pringle, William Joseph James, Muguo Chen, William B. Yelon, I. Dubenko, Naushad Ali, Ph. I'Héritier
Physics Faculty Research & Creative Works
The crystallographic and magnetic properties of LaN_{5x}Mn_{x} with x = 1, 1.5, and 2, have been investigated using xray and neutron diffraction, vibrating sample magnetometer and superconducting quantum interference device measurements. All the samples crystallize in the hexagonal CaCu_{5}type (P6/mmm) structure. Manganese atoms preferentially occupy the 3 g site in the LaNi_{5} structure. The bulk magnetization of the LaNi_{5x}Mn_{x} powder samples decreases rapidly as nickel is replaced by manganese. A ferrimagnetic model is applied to describe the magnetic structure of the LaNi_{5x}Mn_{x} samples for x = 1.5 ...
Neutron Scattering From Aerosols: Intraparticle Structure Factor, Guinier Analysis Of Particle Speed, And Crossed Beam Kinematics, Gerald Wilemski
Neutron Scattering From Aerosols: Intraparticle Structure Factor, Guinier Analysis Of Particle Speed, And Crossed Beam Kinematics, Gerald Wilemski
Physics Faculty Research & Creative Works
A theoretical formalism for neutron scattering from systems of particles is applied to liquid nanodroplet aerosols. A term arising from intraparticle, intermolecular correlations is identified. The kinematical theory of two body scattering is recast into a form convenient for interpreting the results of experiments with crossed beams of neutrons and aerosol particles. Based on a theoretical analysis of the scattered intensity in the Guinier region, a method for determining the particle velocity directly from the experimental data is outlined. The method is not restricted by assumptions about particle shape, composition, uniformity, or size distribution.
Electron Correlations Observed Through Intensity Interferometry, Michael Schulz, Robert Moshammer, Wayne M. Schmitt, Holger Kollmus, Bernold Feuerstein, Rido Mann, Siegbert Hagmann, Joachim Hermann Ullrich
Electron Correlations Observed Through Intensity Interferometry, Michael Schulz, Robert Moshammer, Wayne M. Schmitt, Holger Kollmus, Bernold Feuerstein, Rido Mann, Siegbert Hagmann, Joachim Hermann Ullrich
Physics Faculty Research & Creative Works
Intensity interferometry was applied to study electron correlations in doubly ionizing ionatom collisions. In this method, the probability to find two electrons emitted in the same double ionization event with a certain momentum difference is compared to the corresponding probability for two uncorrelated electrons from two independent events. The ratio of both probabilities, the socalled correlation function, is found to sensitively reveal electron correlation effects, but it is rather insensitive to the collision dynamics.