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

Physical Sciences and Mathematics Commons™

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

Physics Faculty Research & Creative Works

Discipline
Keyword
Publication Year

Articles 1381 - 1410 of 1959

Full-Text Articles in Physical Sciences and Mathematics

Nonlinear Field Dependence Of The Mobility Of A Charge Subjected To A Superposition Of Dichotomous Stochastic Potentials, A. M. Kenkre, Marek Kus, David H. Dunlap, Paul Ernest Parris Jul 1998

Nonlinear Field Dependence Of The Mobility Of A Charge Subjected To A Superposition Of Dichotomous Stochastic Potentials, A. M. Kenkre, Marek Kus, David H. Dunlap, Paul Ernest Parris

Physics Faculty Research & Creative Works

A general prescription is presented to address a large variety of forms of the nonlinear dependence of the static charge mobility on the applied electric field. The system consists of a classical charge subjected to an arbitrarily strong steady state electric field and to a stochastic potential consisting of a linear superposition of an unlimited number of dichotomous potentials in one-dimensional space. It is shown that the nonlinear mobility can be calculated for arbitrary forms of the density function of the individual dichotomous components of the stochastic potential. Specific cases of physical interest are analyzed. One of them provides a …

Go to article

Particulate Sizing And Emission Indices For A Jet Engine Exhaust Sampled At Cruise, Donald E. Hagen, Philip D. Whitefield, J. Paladino, Max B. Trueblood, H. Lilenfeld May 1998

Particulate Sizing And Emission Indices For A Jet Engine Exhaust Sampled At Cruise, Donald E. Hagen, Philip D. Whitefield, J. Paladino, Max B. Trueblood, H. Lilenfeld

Physics Faculty Research & Creative Works

Particle size and emission indices measurements for jet engines, primarily the Rolls Royce RB211 engines on a NASA 757 aircraft are reported. These data were used to estimate the fraction of fuel sulfur that was converted to particulates. These measurements were made in-situ with the sampling aircraft several kilometers behind the source. Some complimentary ground measurements on the same source aircraft and engines are also reported. Significant differences are seen between the ground observations and the in-situ observations, indicating that plume processes are changing the aerosol' s characteristics.

Go to article

Sources And Chemistry Of Noₓ In The Upper Troposphere Over The United States, Lyatt Jaegle, Daniel J. Jacob, Yuhua Wang, Andrew J. Weinheimer, Brian A. Ridley, Teresa L. Campos, Glen W. Sachse, Donald E. Hagen May 1998

Sources And Chemistry Of Noₓ In The Upper Troposphere Over The United States, Lyatt Jaegle, Daniel J. Jacob, Yuhua Wang, Andrew J. Weinheimer, Brian A. Ridley, Teresa L. Campos, Glen W. Sachse, Donald E. Hagen

Physics Faculty Research & Creative Works

The origin of NOx in the upper troposphere over the central United States is examined using aircraft observations obtained during the SUCCESS campaign in April–May of 1996. Correlations between NOy (sum of NOx and its oxidation products) and CO at 8–12 km altitude indicate that NOx originates primarily from convective transport of polluted boundary layer air. Lightning and aircraft emissions appear to be only minor sources of NOx. Chemical steady state model calculations constrained by local observations of NO underestimate the measured NOx/NOy concentration ratio at 8–12 km altitude by a …

Go to article

Particulate Sizing And Emission Indices For A Jet Engine Exhaust Sampled At Cruise, Donald E. Hagen, Philip D. Whitefield, Jonathan D. Paladino, Max B. Trueblood May 1998

Particulate Sizing And Emission Indices For A Jet Engine Exhaust Sampled At Cruise, Donald E. Hagen, Philip D. Whitefield, Jonathan D. Paladino, Max B. Trueblood

Physics Faculty Research & Creative Works

Particle size and emission indices measurements for jet engines, primarily the Rolls Royce RB211 engines on a NASA 757 aircraft are reported. These data were used to estimate the fraction of fuel sulfur that was converted to particulates. These measurements were made in-situ with the sampling aircraft several kilometers behind the source. Some complimentary ground measurements on the same source aircraft and engines are also reported. Significant differences are seen between the ground observations and the in-situ observations, indicating that plume processes are changing the aerosol's characteristics.

Go to article

Solvable Model Of Two-Dimensional Dilaton Gravity Coupled To A Massless Scalar Field, Marco Cavaglia Apr 1998

Solvable Model Of Two-Dimensional Dilaton Gravity Coupled To A Massless Scalar Field, Marco Cavaglia

Physics Faculty Research & Creative Works

We present a solvable model of two-dimensional dilaton-gravity coupled to a massless scalar field. We locally integrate the field equations and briefly discuss the properties of the solutions. For a particular choice of the coupling between the dilaton and the scalar field the model can be interpreted as the two-dimensional effective theory of 2+1 cylindrical gravity minimally coupled to a massless scalar field.

Go to article

Aerosol Particle Scavenging By Fog And Haze Droplets, Josef Podzimek Jan 1998

Aerosol Particle Scavenging By Fog And Haze Droplets, Josef Podzimek

Physics Faculty Research & Creative Works

Droplet imprints in thin gelatin layers have been used for the investigation of coarse particles embedded in fog (haze) droplets in comparison to interstitial particles. Droplet samples were taken in less polluted regions of Missouri and Illinois and also in more polluted marine-urban environment in Italy. Considerable differences in particle size distribution and particle location inside the droplets have been found in samples collected on four sampling sites. The deduced relationships can be applied for the description of the aerosol scavenging process in fogs. The pollution of fog (haze) droplets may be related to the droplet mean volume radius and …

Go to article

A Neutron Diffraction Structural Study Of R₂Fe₁₇₋ₓalx(C) (R=Tb,Ho) Alloys, William B. Yelon, H. Luo, Mingxing Chen, W. C. Chang, S. H. Tsai Jan 1998

A Neutron Diffraction Structural Study Of R₂Fe₁₇₋ₓalx(C) (R=Tb,Ho) Alloys, William B. Yelon, H. Luo, Mingxing Chen, W. C. Chang, S. H. Tsai

Physics Faculty Research & Creative Works

No abstract provided.

Go to article

Neutron Diffraction And Frequency Dependence Of The A.C. Susceptibility Of The System Zncr₂Xal₂-₂Xs₄, M. Hamedoun, A. Hourmatallah, N. Benzakour, K. Mediouri, J. Ilali, William B. Yelon, H. Luo Jan 1998

Neutron Diffraction And Frequency Dependence Of The A.C. Susceptibility Of The System Zncr₂Xal₂-₂Xs₄, M. Hamedoun, A. Hourmatallah, N. Benzakour, K. Mediouri, J. Ilali, William B. Yelon, H. Luo

Physics Faculty Research & Creative Works

No abstract provided.

Go to article

Magnetic And Thermal Properties Of Pr In La₁₋ₓprxbacacu₃O₇ System With 0.0, Rajvir Singh, S. Uma, E. Gmelin, William B. Yelon, V. P. S. Awana, S. X. Dou, A. V. Narlikar, Satish K. Malik Jan 1998

Magnetic And Thermal Properties Of Pr In La₁₋ₓprxbacacu₃O₇ System With 0.0, Rajvir Singh, S. Uma, E. Gmelin, William B. Yelon, V. P. S. Awana, S. X. Dou, A. V. Narlikar, Satish K. Malik

Physics Faculty Research & Creative Works

No abstract provided.

Go to article

Pressure Induced Reversal Of The Volume Expansion Caused By Interstitial Nitrogen In Nd₂Fe₁₇N₃, R. Luo, William B. Yelon, Yusheng S.. Zhao, M. Ellouze, Ph. I'Héritier, G. K. Marasinghe, Peter C. Ezekwenna, R. B. Von Dreele, William Joseph James Jan 1998

Pressure Induced Reversal Of The Volume Expansion Caused By Interstitial Nitrogen In Nd₂Fe₁₇N₃, R. Luo, William B. Yelon, Yusheng S.. Zhao, M. Ellouze, Ph. I'Héritier, G. K. Marasinghe, Peter C. Ezekwenna, R. B. Von Dreele, William Joseph James

Physics Faculty Research & Creative Works

No abstract provided.

Go to article

Complete Single-Ionization Momentum Spectra For Strong Perturbation Collisions, Ronald E. Olson, C. J. Wood, H. Schmidt-Böcking, R. Moshammer, J. Ullrich Jan 1998

Complete Single-Ionization Momentum Spectra For Strong Perturbation Collisions, Ronald E. Olson, C. J. Wood, H. Schmidt-Böcking, R. Moshammer, J. Ullrich

Physics Faculty Research & Creative Works

The combination of recoil ion and ionized electron momentum spectroscopy provides an unparalleled method to investigate the details of ion-atom collision dynamics in kinematically complete experiments. To predict single ionization scattering behavior at the level now realized by experiment, the classical trajectory three-body Monte Carlo method has been used to obtain complete momenta information for the ionized electron, recoil ion, and projectile in the collision plane defined by the incident projectile and outgoing recoil ion. Strongly coupled systems were considered where the charge state of the projectile divided by the speed of the collision [Formula Presented] is greater than unity. …

Go to article

Ionization Dynamics In Fast Ion-Atom Collisions. Ii. Final-State Momentum Distributions Of The Ionization Products In Collisions Of He With Bare Carbon Ions, Lokesh C. Tribedi, P. Richard, Y. D. Wang, C. D. Lin, Ronald E. Olson, L. Gulyas Jan 1998

Ionization Dynamics In Fast Ion-Atom Collisions. Ii. Final-State Momentum Distributions Of The Ionization Products In Collisions Of He With Bare Carbon Ions, Lokesh C. Tribedi, P. Richard, Y. D. Wang, C. D. Lin, Ronald E. Olson, L. Gulyas

Physics Faculty Research & Creative Works

We have used the energy and angular distributions of the low-energy electron emission cross sections from the preceding paper [Lokesh C. Tribedi et al., Phys. Rev. A 58, 3619 (1998)] to derive the doubly differential final-state longitudinal momentum distributions of the electrons, recoil ions, and projectiles in ion-atom ionization for [Formula Presented] The complementary nature of the electron spectroscopy and the recoil-ion momentum spectroscopy have been investigated using a formulation based on three-body kinematics to explore the ionization dynamics in detail. The influence of the three-body ionization as well as the binary-encounter processes on the recoil-ion (and projectile) longitudinal momentum …

Go to article

Effect Of Exchange Interactions At Antiferromagnetic/Ferromagnetic Interfaces On Exchange Bias And Coercivity, D. Dimitrov, Shufeng Zhang Jan 1998

Effect Of Exchange Interactions At Antiferromagnetic/Ferromagnetic Interfaces On Exchange Bias And Coercivity, D. Dimitrov, Shufeng Zhang

Physics Faculty Research & Creative Works

We report on the correlation between unidirectional and uniaxial anisotropy in exchange-biased ferromagnetic Permalloy layers. The dependence of exchange bias and coercivity on temperature and the antiferromagnetic and ferromagnetic layer thickness was studied and compared with the predictions of different theoretical models. A thorough explanation of the experimental data is provided by theoretical extension of Malozemoff's model. © 1998 The American Physical Society.

Go to article

Near-Field Measurements On Contrail Properties From Fuels With Different Sulfur Content, Andreas Petzold, Reinhold Busen, Franz Peter Schroder, Robert Baumann, Markus Kuhn, Johan Strom, Donald E. Hagen, Philip D. Whitefield, Darrel G. Baumgardner, Frank Arnold, Stephan Borrmann, Ulrich Schumann Dec 1997

Near-Field Measurements On Contrail Properties From Fuels With Different Sulfur Content, Andreas Petzold, Reinhold Busen, Franz Peter Schroder, Robert Baumann, Markus Kuhn, Johan Strom, Donald E. Hagen, Philip D. Whitefield, Darrel G. Baumgardner, Frank Arnold, Stephan Borrmann, Ulrich Schumann

Physics Faculty Research & Creative Works

Microphysical properties of jet exhaust aerosol and contrails were studied in the near field of the emitting aircraft for different fuel sulfur contents. Measurements were performed behind two different aircraft (ATTAS test aircraft of type VFW 614 and Airbus A310-300) using fuels with sulfur contents of 6 ppm and 2700 ppm, respectively. At closest approach (plume age < 1 s), the total number concentrations exceeded the measuring range of the condensation particle counter, i.e., N > 105 cm-3. The concentration of the dry accumulation mode aerosol, i.e., predominantly soot particles, was not affected by the fuel sulfur content. At a plume age of 10 s, an increase in total number concentration (Dp > 0.01 μm) by a …

Go to article

Bound Μ⁺Μˉ System, Ulrich D. Jentschura, Gerhard Soff, Vladimir G. Ivanov, Savely Karshenboim Dec 1997

Bound Μ⁺Μˉ System, Ulrich D. Jentschura, Gerhard Soff, Vladimir G. Ivanov, Savely Karshenboim

Physics Faculty Research & Creative Works

We consider the hyperfine structure, the atomic spectrum, and the decay channels of the bound μ+μ- system (dimuonium). The annihilation lifetimes of low-lying atomic states of the system lie in the 10-12 s range. The decay rates could be measured by detection of the decay products (high-energy photons or electron-positron pairs). The hyperfine-structure splitting of the dimuonic system and its decay rate are influenced by electronic vacuum polarization effects in the far timelike asymptotic region. This constitutes a previously unexplored kinematic regime. We evaluate next-to-leading-order radiative corrections to the decay rate of low-lying atomic states. We …

Go to article

Nonlinear Response Theory: Transport Coefficients For Driving Fields Of Arbitrary Magnitude, Paul Ernest Parris, Marek Kus, David H. Dunlap, Vasudev M. Kenkre Nov 1997

Nonlinear Response Theory: Transport Coefficients For Driving Fields Of Arbitrary Magnitude, Paul Ernest Parris, Marek Kus, David H. Dunlap, Vasudev M. Kenkre

Physics Faculty Research & Creative Works

A theory of nonlinear response is developed for driving fields of arbitrary magnitude. Exact and usable expressions are provided for electrical and thermal mobility, and related transport coefficients, in terms of correlation functions of the system. A generalization into the nonlinear domain is provided of the Wiedemann-Franz law connecting electrical and thermal response and of the Einstein relation relating the diffusion constant and the mobility.

Go to article

Lamb Shift Of 3p And 4p States And The Determination Of Α, Ulrich D. Jentschura, Gerhard Soff, Peter J. Mohr Sep 1997

Lamb Shift Of 3p And 4p States And The Determination Of Α, Ulrich D. Jentschura, Gerhard Soff, Peter J. Mohr

Physics Faculty Research & Creative Works

The fine-structure interval of P states in hydrogenlike systems can be determined theoretically with high precision, because the energy levels of P states are only slightly influenced by the structure of the nucleus. Therefore a measurement of the fine structure may serve as an excellent test of QED in bound systems, or alternatively as a means of determining the fine-structure constant a with very high precision. In this paper an improved analytic calculation of higher-order binding corrections to the one-loop self-energy of 3P and 4P states in hydrogenlike systems with a low nuclear charge number Z is presented. The method …

Go to article

Quantum Coulomb Glass Within A Hartree-Fock Approximation, Frank Epperlein, Michael Schreiber, Thomas Vojta Sep 1997

Quantum Coulomb Glass Within A Hartree-Fock Approximation, Frank Epperlein, Michael Schreiber, Thomas Vojta

Physics Faculty Research & Creative Works

We study the influence of electron-electron interactions on the electronic properties of disordered materials. In particular, we consider the insulating side of a metal-insulator transition where screening breaks down and the electron-electron interaction remains long ranged. The investigations are based on the quantum Coulomb glass, a generalization of the classical Coulomb glass model of disordered insulators. The quantum Coulomb glass is studied by decoupling the Coulomb interaction by means of a Hartree-Fock approximation and exactly diagonalizing the remaining localization problem. We investigate the behavior of the Coulomb gap in the density of states when approaching the metal-insulator transition and study …

Go to article

Small Angle Neutron Scattering From Nanodroplet Aerosols, Barbara Ellen Wyslouzil, Janice L. Cheung, Gerald Wilemski, Reinhard Strey Jul 1997

Small Angle Neutron Scattering From Nanodroplet Aerosols, Barbara Ellen Wyslouzil, Janice L. Cheung, Gerald Wilemski, Reinhard Strey

Physics Faculty Research & Creative Works

We report the first measurements of small angle neutron scattering from an aerosol. The aerosol was produced by expanding a D2O-N2 vapor mixture in a supersonic Laval nozzle. The neutron wavelength (0.5 nm) is less than the typical particle size, and we can therefore derive the average particle size (5-8 nm), number density (~1012 cm-3), and polydispersity of the size distribution directly from the experimental data rather than by inferring them from complex models of particle formation and growth. We also predict and observe a Doppler shift-induced anisotropy in the scattering pattern due to …

Go to article

In Situ Observations Of Air Traffic Emission Signatures In The North Atlantic Flight Corridor, Hans Schlager, Paul Konopka, P. Schulte, U. Schumann, H. Ziereis, F. Arnold, M. Klemm, Donald E. Hagen, Philip D. Whitefield, J. Ovarlez May 1997

In Situ Observations Of Air Traffic Emission Signatures In The North Atlantic Flight Corridor, Hans Schlager, Paul Konopka, P. Schulte, U. Schumann, H. Ziereis, F. Arnold, M. Klemm, Donald E. Hagen, Philip D. Whitefield, J. Ovarlez

Physics Faculty Research & Creative Works

Focussed aircraft measurements have been carried out over the eastern North Atlantic to search for signals of air traffic emissions in the flight corridor region. Observations include NO, NO2, HNO3, SO2, O3, H2O, total condensation nuclei (CN), and meteorological parameters. A flight pattern with constant-altitude north-south legs across the major North Atlantic air traffic tracks was flown. Signatures of air traffic emissions were clearly detected for NOx, SO2, and CN with peak concentrations of 2 ppbv, 0.25 ppbv, and 500 cm-3, respectively, exceeding background …

Go to article

Chaotic Behavior And Damage Spreading In The Glauber Ising Model: A Master Equation Approach, Thomas Vojta May 1997

Chaotic Behavior And Damage Spreading In The Glauber Ising Model: A Master Equation Approach, Thomas Vojta

Physics Faculty Research & Creative Works

We investigate the sensitivity of the time evolution of a kinetic Ising model with Glauber dynamics against the initial conditions. To do so we apply the "damage spreading" method, i.e., we study the simultaneous evolution of two identical systems subjected to the same thermal noise. We derive a master equation for the joint probability distribution of the two systems. We then solve this master equation within an effective-field approximation which goes beyond the usual mean-field approximation by retaining the fluctuations though in a quite simplistic manner. The resulting effective-field theory is applied to different physical situations. It is used to …

Go to article

Studies Of V, Nb, Cr, And Zr Substituted 2:17 Compounds And Their Carbides Using Neutron Diffraction, H. Luo, Z. Hu, Muguo Chen, William B. Yelon, G. K. Marasinghe, Peter C. Ezekwenna, William Joseph James, W. C. Chang, S. H. Tsai Apr 1997

Studies Of V, Nb, Cr, And Zr Substituted 2:17 Compounds And Their Carbides Using Neutron Diffraction, H. Luo, Z. Hu, Muguo Chen, William B. Yelon, G. K. Marasinghe, Peter C. Ezekwenna, William Joseph James, W. C. Chang, S. H. Tsai

Physics Faculty Research & Creative Works

Samples of Nd2Fe17-xTxCy with T=V, Nb, Cr, and Zr were prepared by melting of the constituent elements including C and studied by neutron diffraction. Comparing with their uncarbided counterparts, we found that the substituents transfer, more or less, from the 6c site to the 18f and 18h sites with the introduction of C atoms. This behavior appears to relate to the electronegativities between the C atoms and the early transition series elements because the 18f and 18h sites are near neighbors of the interstitial C site. However, the C effects in the V. …

Go to article

Nonanalytic Behavior Of The Spin Susceptibility In Clean Fermi Systems, Dietrich Belitz, Theodore R. Kirkpatrick, Thomas Vojta Apr 1997

Nonanalytic Behavior Of The Spin Susceptibility In Clean Fermi Systems, Dietrich Belitz, Theodore R. Kirkpatrick, Thomas Vojta

Physics Faculty Research & Creative Works

The wave vector and temperature-dependent static spin susceptibility, Xs(Q, T), of clean interacting Fermi systems is considered in dimensions 1 ≤ d ≤ 3. We show that at zero temperature Xs is a nonanalytic function of |Q|, with the leading nonanalyticity being |Q|d-1 for 1 < d < 3, and Q2ln|Q| for d = 3. For the homogeneous spin susceptibility we find a nonanalytic temperature dependence Td-1 for 1 < d < 3. We give qualitative mode-mode coupling arguments to that effect, and corroborate these arguments by a perturbative calculation to second order in the electron-electron interaction amplitude. The implications of this, in particular for itinerant ferromagnetism, are discussed. We also point out the relation between our findings and established perturbative results for one-dimensional systems, as well as for the temperature dependence of Xs(Q = 0) in d = 3.

Go to article

Monte Carlo Simulations Of The Dynamical Behavior Of The Coulomb Glass, Torsten Wappler, Thomas Vojta, Michael Schreiber Mar 1997

Monte Carlo Simulations Of The Dynamical Behavior Of The Coulomb Glass, Torsten Wappler, Thomas Vojta, Michael Schreiber

Physics Faculty Research & Creative Works

We study the dynamical behavior of disordered many-particle systems with long-range Coulomb interactions by means of damage-spreading simulations. In this type of Monte Carlo simulation one investigates the time evolution of the damage, i.e., the difference of the occupation numbers of two systems, subjected to the same thermal noise. We analyze the dependence of the damage on temperature and disorder strength. For zero disorder the spreading transition coincides with the equilibrium phase transition, whereas for finite disorder we find evidence for a dynamical phase transition well below the transition temperature of the pure system.

Go to article

Velocity Space "Snapshots" Of Continuum Electrons Produced By Slow, Bare, Highly Charged Ions: Saddle-Point Electrons?, M. Abdallah, S. Kravis, C. L. Cocke, Y. D. Wang, M. Stöckli, Ronald E. Olson Jan 1997

Velocity Space "Snapshots" Of Continuum Electrons Produced By Slow, Bare, Highly Charged Ions: Saddle-Point Electrons?, M. Abdallah, S. Kravis, C. L. Cocke, Y. D. Wang, M. Stöckli, Ronald E. Olson

Physics Faculty Research & Creative Works

Comprehensive velocity-space "snapshots" of the electron continua produced by the impact of ions on He at a projectile velocity of 1.63 a.u. have been measured for the bare projectiles of p, He, C, O and Ne. For the three highly charged ions, this velocity lies in the "ionization threshold" region where electron capture dominates the reaction. The experimental technique projects the distribution of soft continuum electrons onto a two-dimensional detector in such a way that the velocity-space distribution for all electrons with laboratory energies in the range from 0-30eV is accurately imaged. The data show no evidence for a saddle-point …

Go to article

Momentum Spectra For Single And Double Electron Ionization Of He In Relativistic Collisions, C. J. Wood, Ronald E. Olson, W. Schmitt, R. Moshammer, J. Ullrich Jan 1997

Momentum Spectra For Single And Double Electron Ionization Of He In Relativistic Collisions, C. J. Wood, Ronald E. Olson, W. Schmitt, R. Moshammer, J. Ullrich

Physics Faculty Research & Creative Works

The complete momentum spectra for single and double ionization of He by [Formula Presented] [Formula Presented] [Formula Presented] have been investigated using a classical trajectory Monte Carlo method corrected for the relativistic projectile. The [Formula Presented] electron-electron interaction has been included in the post-collision region for double ionization to incorporate the effects of both the nuclear-electron and electron-electron ionizing interactions, and to access the effects of electron correlation in the electron spectra. Experimental measurements were able to determine the longitudinal momentum spectra for single ionization; these observations are in accordance with the theoretical predictions for the three-body momentum balance between …

Go to article

Droplet Concentration And Size Distribution In Haze And Fog, Josef Podzimek Jan 1997

Droplet Concentration And Size Distribution In Haze And Fog, Josef Podzimek

Physics Faculty Research & Creative Works

Fog (haze) droplet concentrations and size distributions were measured at five sampling sites representing rural and urban regions and a highly polluted marine-urban environment. Droplet imprints in a thin gelatine layer were evaluated and compared to the measurement by light scattering instruments. This enabled conditions for the application of the logarithmic-normal size distribution and for the classification of typical fog droplet size distributions to be established. In particular, the parameters featuring the width and asymmetry of a size distribution were suggested and calculated. Advantages and drawbacks of the applied droplet sampling and evaluation technique are discussed in more detail. © …

Go to article

Three-Body Models Of Electron-Hydrogen Ionization, Stephenie J. Jones, Don H. Madison, Dmitry A. Konovalov Jan 1997

Three-Body Models Of Electron-Hydrogen Ionization, Stephenie J. Jones, Don H. Madison, Dmitry A. Konovalov

Physics Faculty Research & Creative Works

In this paper, we report calculations of electron-hydrogen ionization whereby the final-state wave Function is approximated by recently reported analytical three-body wave functions. In a first model we use the wave function of Alt and Mukhamedzhanov [Phys. Rev. A 47, 2004 (1993)], and in a second model we use the wave function of Berakdar [Phys. Rev. A 53, 2314 (1996)].

Go to article

Observation Of Upper Tropospheric Sulfur Dioxide- And Acetone-Pollution: Potential Implications For Hydroxyl Radical And Aerosol Formation, F. Arnold, J. Schneider, K. Gollinger, H. Schlager, P. Schulte, Donald E. Hagen, Philip D. Whitefield, Peter F. J. Van Velthoven Jan 1997

Observation Of Upper Tropospheric Sulfur Dioxide- And Acetone-Pollution: Potential Implications For Hydroxyl Radical And Aerosol Formation, F. Arnold, J. Schneider, K. Gollinger, H. Schlager, P. Schulte, Donald E. Hagen, Philip D. Whitefield, Peter F. J. Van Velthoven

Physics Faculty Research & Creative Works

Aircraft-based measurements of sulfur dioxide, acetone, carbon dioxide, and condensation nuclei (CN) were made over the north-eastern Atlantic at upper tropospheric altitudes, around 9000 m. On October 14, 1993, strong SO 2- and acetone-pollution (both up to 3 ppbv) were observed, which were accompanied by a CO 2-enhancement of up to 6 ppmv, and large CN-concentrations of up to about 1500 cm -3 (for radii ≥ 6 nm). CN, excess CO 2, and to a lesser degree also acetone, were positively correlated with SO 2. Air mass trajectory analyses indicate, that most of the air masses …

Go to article

Ionization Of Helium In The Attosecond Equivalent Light Pulse Of 1 Gev/Nucleon U⁹²⁺ Projectiles, R. Moshammer, W. Schmitt, J. Ullrich, H. Kollmus, A. Cassimi, R. Dörner, O. Jagutzki, R. Mann, Ronald E. Olson, H. T. Prinz, H. Schmidt-Böcking, L. Spielberger Jan 1997

Ionization Of Helium In The Attosecond Equivalent Light Pulse Of 1 Gev/Nucleon U⁹²⁺ Projectiles, R. Moshammer, W. Schmitt, J. Ullrich, H. Kollmus, A. Cassimi, R. Dörner, O. Jagutzki, R. Mann, Ronald E. Olson, H. T. Prinz, H. Schmidt-Böcking, L. Spielberger

Physics Faculty Research & Creative Works

Single and double ionization of helium by 1 GeV/nucleon U92+ impact was explored in a kinematically complete experiment. The relativistic ion generates a subattosecond (10−18s) superintense (I > 1019W/cm2) electromagnetic pulse, which is interpreted as a field of equivalent photons (Weizsäcker-Williams method). Cross sections, the emission characteristics of ions and electrons as well as momentum balances, are quantitatively discussed in terms of photoionization of the atom in this broadband, ultrashort virtual photon field. © 1997 The American Physical Society.

Go to article

First Prev Next Last