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Full-Text Articles in Physics
Calculation Of Electron Capture Cross Sections Of Collisions Of Be ²⁺ On H, A. E. Wetmore, H. R. Cole, Ronald E. Olson
Calculation Of Electron Capture Cross Sections Of Collisions Of Be ²⁺ On H, A. E. Wetmore, H. R. Cole, Ronald E. Olson
Physics Faculty Research & Creative Works
Using the perturbed stationary state method, including electron translation factors, the authors have calculated electron capture cross sections for the helium-like ions Be2+ and B3+ incident on ground-state atomic hydrogen. The molecular structure calculation employs pseudo-potentials to represent the inactive K-shell electrons on the incident ions. The calculated cross sections vary rapidly in the 107 cm s-1 velocity range (E approximately 1 keV amu-1). The calculations show preferential transfer to the Be+(2s) and the B2+(2p) product states. The calculations for B3++H are in good agreement with experimental measurements of Cradall et al …
Double Electron Transitions In Collisions Between Multiply Charged Ions And Helium Atoms, Ronald E. Olson, A. E. Wetmore, M. L. Mckenzie
Double Electron Transitions In Collisions Between Multiply Charged Ions And Helium Atoms, Ronald E. Olson, A. E. Wetmore, M. L. Mckenzie
Physics Faculty Research & Creative Works
A semiclassical model for He is applied to the study of multiply charged ions colliding with He at intermediate energies. Single and double-electron capture and ionisation and capture-ionisation reactions are studied for incident-ion charge states q=+1 to +50 at 1 MeV amu-1. For charge states q>or approximately=+10, single electron capture is found to be dominated by a two-electron transition in which one electron is captured and the other is ionised.
Negative Ion Drift Velocities In Mixtures Of Methane And Sulphur Hexafluoride, M. C. Cornell, Ian M. Littlewood
Negative Ion Drift Velocities In Mixtures Of Methane And Sulphur Hexafluoride, M. C. Cornell, Ian M. Littlewood
Physics Faculty Research & Creative Works
The velocities of negative ions drifting in mixtures of methane and Sulphur hexafluoride have been measured. Measurements were made as a function of gas composition, reduced electric field strength between 3 and 185 Td, and total gas pressure in the range 100-600 Torr at 300K. The data indicate that SF 6- (SF6) ions are the dominant ion in all of the gas mixtures studied. Extrapolation of the data using Blanc's Law was used to determine the velocity of Sulphur hexafluoride ions drifting in pure methane.
Photoconductivity Parameters In Lithium Niobate, Robert Gerson, J. F. Kirchhoff, L. E. Halliburton, D. A. Bryan
Photoconductivity Parameters In Lithium Niobate, Robert Gerson, J. F. Kirchhoff, L. E. Halliburton, D. A. Bryan
Physics Faculty Research & Creative Works
Measurements on a variety of doped (magnesium and/or iron) and undoped lithium niobate crystals in the oxidized state demonstrate an Arrhenius dependence of dark conductivity on reciprocal temperature between 460 and 590 K. All of the crystals had roughly the same conductivity and activation energy (1.21 eV) over the temperature range, implying that all have about the same free-carrier concentration and mobility. The enhanced photoconductivity of magnesium-doped lithium niobate is attributed to a greatly reduced trapping cross section of Fe3+ for electrons, the smaller cross section being due to a changed substitutional site for Fe3+. The Fe …
Experimental Test Of Higher-Order Electron-Capture Processes In Collisions Of Fast Protons With Atomic Hydrogen, Hans G. Vogt, Reinhold S. Schuch, Edson L B Justiniano, Michael Schulz, W. Schwab
Experimental Test Of Higher-Order Electron-Capture Processes In Collisions Of Fast Protons With Atomic Hydrogen, Hans G. Vogt, Reinhold S. Schuch, Edson L B Justiniano, Michael Schulz, W. Schwab
Physics Faculty Research & Creative Works
We present measurements of the angular distribution of fast hydrogen atoms formed by electron capture of 2.8- and 5.0-MeV protons in atomic hydrogen. In the angular region of the Thomas peak (0.47 mrad) the experimental results obtained with this pure three-body collision system are in reasonable agreement with a strong-potential Born calculation and the impulse approximation, but not with other higher-order theories.
Two-Step Stabilization Of Autoionizing States, J. Greg Story, Linn D. Van Woerkom, William E. Cooke
Two-Step Stabilization Of Autoionizing States, J. Greg Story, Linn D. Van Woerkom, William E. Cooke
Physics Faculty Research & Creative Works
A two-step process using internal conversion and fluorescence to stabilize the 6P3/211d autoionizing state of barium has been observed. The internal conversion produces very highly excited autoionizing Rydberg states, which then emit fluorescence to produce singly excited, bound states. Inclusion of this process should bring calculations closer to agreement with recent measurements of dielectronic recombination.
Measurement Of The Lifetime Of The Metastable 5d3/226d3/2, J=0 Autoionizing State Of Barium, Linn D. Van Woerkom, J. Greg Story, William E. Cooke
Measurement Of The Lifetime Of The Metastable 5d3/226d3/2, J=0 Autoionizing State Of Barium, Linn D. Van Woerkom, J. Greg Story, William E. Cooke
Physics Faculty Research & Creative Works
We report a measurement of the lifetime of the metastable 5d3/226d3/2, J=0 autoionizing state of barium. We have determined the lifetime to be 190(10) ns.
Application Of A Scaled Homogeneous Nucleation-Rate Formalism To Experimental Data At T≪TC, Barbara N. Hale
Application Of A Scaled Homogeneous Nucleation-Rate Formalism To Experimental Data At T≪TC, Barbara N. Hale
Physics Faculty Research & Creative Works
It is pointed out that for temperatures T<0.5Tc, where Tc is the critical temperature, the classical steady-state nucleation-rate formalism of Becker and Doring predicts an approximate critical supersaturation ratio Scr (for the onset of nucleation) given by lnScr/Ω3/2~0.53(Tc/T-1)3/2. Ω is a material-dependent quantity approximately equal to the excess surface entropy per molecule. For most substances Ω ~ 2.0 and for associated liquids Ω ~ 1.5.The experimental data (for nucleation from vapor to liquid) from diffusion chamber and nozzle beam studies are found to be consistent with the above …
Energy Transfer Collisions Between Vibrationally Excited Molecular Nitrogen And Atoms, Laird D. Schearer
Energy Transfer Collisions Between Vibrationally Excited Molecular Nitrogen And Atoms, Laird D. Schearer
Physics Faculty Research & Creative Works
Chemiluminescent reactions between metastable states of molecular nitrogen and atoms are used to determine the vibrational temperatures of these Non radiating molecular systems. The excitation rates of Na, Mg, Cd, and Zn are used to obtain the vibrational temperature of N2(X 1Σ) and N2(A 3Σ) states in a fast-flowing nitrogen afterglow. The exponential dependence of the intensities of the emission from atoms excited by the energy transfer collisions on the energy of the level yields vibrational temperatures on the order of 3100 K. We also report the presence of apparent strong selection rules on the total spin of the system …
Lna: A New Cw Nd Laser Tunable Around 1.05 And 1.08 Μm, Laird D. Schearer, Michele Leduc, Daniel Vivien, Anne Marie Lejus, Jeanine Thery
Lna: A New Cw Nd Laser Tunable Around 1.05 And 1.08 Μm, Laird D. Schearer, Michele Leduc, Daniel Vivien, Anne Marie Lejus, Jeanine Thery
Physics Faculty Research & Creative Works
We have investigated the CW laser properties of the lanthamide hexa-aluminate La0.9Nd0.1MgAl11O19 at room temperature. When a I cm long crystal is pumped by an Ar+ laser (514 nm) or a Kr+ laser (752 nm), CW emission is obtained with slope efficiencies of 10 and 26 percent, respectively. A four-plate Lyot filter in the cavity forces the LNA crystal to oscillate in either of the two major bands centered at 10 820 A (tuning range 80 A) and 10 545 A (tuning range 35 Å). Copyright © 1986 by The Institute of Electrical and Electronics Engineers, Inc.
Comments On The Raindrop Problem, I. Adawi
Comments On The Raindrop Problem, I. Adawi
Physics Faculty Research & Creative Works
No abstract provided.
The Spin‐1 Anisotropic Heisenberg Ferromagnet With Biquadratic Exchange, Harry A. Brown
The Spin‐1 Anisotropic Heisenberg Ferromagnet With Biquadratic Exchange, Harry A. Brown
Physics Faculty Research & Creative Works
No abstract provided.
Structure In The Energy Dependence Of High-Energy Electron-Capture Cross Sections, W. G. Graham, E. M. Bernstein, M. W. Clark, J. A. Tanis, K. H. Berkner, P. Gohil, R. J. Mcdonald, A. S. Schlachter, J. W. Stearns, Robert H. Mcfarland, T. J. Morgan, A. M̈Ller
Structure In The Energy Dependence Of High-Energy Electron-Capture Cross Sections, W. G. Graham, E. M. Bernstein, M. W. Clark, J. A. Tanis, K. H. Berkner, P. Gohil, R. J. Mcdonald, A. S. Schlachter, J. W. Stearns, Robert H. Mcfarland, T. J. Morgan, A. M̈Ller
Physics Faculty Research & Creative Works
Previous experimental and theoretical work has found electron capture to be a monotonically decreasing function of energy in fast ion-atom collisions. We report here the experimental observation of nonmonotonic behavior of the electron-capture cross sections in fast collisions of calcium ions, in charge states 16+ to 19+, with molecular hydrogen, in the energy range 97368 MeV. The structure observed in the measured cross sections is attributed to the contribution of resonant transfer and excitation to electron capture. © 1986 The American Physical Society.
Tuning Characteristics And New Laser Lines In An Nd:Yap Cw Laser, Laird D. Schearer, Michele Leduc
Tuning Characteristics And New Laser Lines In An Nd:Yap Cw Laser, Laird D. Schearer, Michele Leduc
Physics Faculty Research & Creative Works
We have investigated the CW laser properties of Nd-doped yttrium-aluminum-perovskite (YAP) in a Kr are-lamp, pumped cavity, Seven laser transitions within the 4F3/2-4I11/2 multiplet have been observed. A simple Lyot filter is used to select the particular transitions. The tuning characteristics of the transitions at 1.0745 and 1.0845 μm were also obtained with the addition of a thin, uncoated etalon within the cavity. Tuning widths of 32 and 23 Å, respectively, were obtained. Copyright © 1986 IEEE
The Three‐Spin Box Product Interaction, Harry A. Brown
The Three‐Spin Box Product Interaction, Harry A. Brown
Physics Faculty Research & Creative Works
The three‐spin interaction in the form of a box product, σ1 x σ2 · σ3, is investigated including additional interaction terms in the Hamiltonian in the forms \document class{article}\page style{empty}\begin{document}$ \sum\limits_i {\sigma _{iz},} \sum\limits_{ij} {\sigma _{iz} \sigma _{jz}} $\end{document}, and πiσiz. With the relative strengths considered as parameters, the thermodynamic properties are evaluated as a function of temperature and show considerable variety. Both second‐ and first‐order phase transitions are found. Copyright © 1986 WILEY‐VCH Verlag GmbH & Co. KGaA
Erratum: Dipole Moment And Potential Energy Functions Of The X ¹∑+ And A1∑+ States Of Nah. (The Journal Of Chemical Physics (1984) 80 (356)), W. T. Zemke, Ronald E. Olson, K. K. Verma, W. C. Stwalley, B. Liu
Erratum: Dipole Moment And Potential Energy Functions Of The X ¹∑+ And A1∑+ States Of Nah. (The Journal Of Chemical Physics (1984) 80 (356)), W. T. Zemke, Ronald E. Olson, K. K. Verma, W. C. Stwalley, B. Liu
Physics Faculty Research & Creative Works
No abstract provided.
General Features Of The Aerosol Observed In The Guinean Savannah At The Level Of The Itcz Influence Of The Drought, F. Désalmand, R. Serpolay, Josef Podzimek
General Features Of The Aerosol Observed In The Guinean Savannah At The Level Of The Itcz Influence Of The Drought, F. Désalmand, R. Serpolay, Josef Podzimek
Physics Faculty Research & Creative Works
The stagnation and mixing of various air masses at the level of the ITCZ in the dry season, together with the absence of rain, favor, in the Guinean savannah, the formation of a well-aged and homogeneous aerosol made up of very active mixed nuclei. When the drought increases, the aerosol always remains an aged one, i.e. absence of particles with radius r < 0.02 μm, no nucleation mode. However, different properties show a younger and less homogeneous aerosol, i.e. very high counts in all the categories of particles (the concentration of nuclei activated at the supersaturation S {reversed tilde equals} 0.32% reaches 9960 cm-3), poor correlations between the concentrations of various groups of particles and no fog. When the fires are frequent and spread all over the savannah, a permanent addition of new particles to the local background aerosol (due to a complicated circulation) prevents the ageing of the aerosol that is observed during the usual drought with a moderate extension of bushfires. © 1986.
Multiple-Electron Capture And Ionization In Collisions Of Highly Stripped Ions With Ar Atoms, A. M̈Ller, B. Schuch, W. Groh, E. Salzborn, H. F. Beyer, P. H. Mokler, Ronald E. Olson
Multiple-Electron Capture And Ionization In Collisions Of Highly Stripped Ions With Ar Atoms, A. M̈Ller, B. Schuch, W. Groh, E. Salzborn, H. F. Beyer, P. H. Mokler, Ronald E. Olson
Physics Faculty Research & Creative Works
Multiple-vacancy production in Ar atoms by 1.4-MeV/u highly stripped ion impact is studied. From a recoil-ionprojectile-ion coincidence experiment charge-state distributions of Ar ions were obtained distinguishing between pure ionization and capture of up to three electrons by N6+,7+, Fe12+,15+,20+,21+, Kr18+, Gd37+, and U30+,36+,41+,44+,4 8+ ions. With increasing projectile charge state the relative abundances of multiply charged recoil ions increase. However, for high-charge-state projectiles, the relative fractions of recoil ions for concomitant electron capture and ionization are found to be independent of projectile charge or species. To interpret the data, classical trajectory Monte Carlo calculations have been made assuming the applicability …
Resonant Transfer And Excitation: Dependence On Projectile Charge State And Target-Electron Momentum Distribution, J. A. Tanis, E. M. Bernstein, M. W. Clark, W. G. Graham, Robert H. Mcfarland, T. J. Morgan, J. R. Mowat, D. W. Mueller, A. Müller, M. P. Stockli, K. H. Berkner, P. Gohil, R. J. Mcdonald, A. S. Schlachter, J. W. Stearns
Resonant Transfer And Excitation: Dependence On Projectile Charge State And Target-Electron Momentum Distribution, J. A. Tanis, E. M. Bernstein, M. W. Clark, W. G. Graham, Robert H. Mcfarland, T. J. Morgan, J. R. Mowat, D. W. Mueller, A. Müller, M. P. Stockli, K. H. Berkner, P. Gohil, R. J. Mcdonald, A. S. Schlachter, J. W. Stearns
Physics Faculty Research & Creative Works
Resonant transfer and excitation (RTE) involving simultaneous electron capture and projectile K-shell excitation has been measured for calcium ions in charge states ranging from neon like to hydrogen like incident on molecular hydrogen over an energy range 100-370 MeV. The results establish a projectile charge-state dependence for RTE and provide a detailed test of theoretical calculations. The effect of the target-electron momentum distribution on the RTE process is demonstrated by comparing with previous results for calcium ions incident on helium. © 1986 The American Physical Society.
Electron Capture And Loss For 2.5-200-Mev 16s13++He Collisions, M. W. Clark, E. M. Bernstein, J. A. Tanis, W. G. Graham, Robert H. Mcfarland, T. J. Morgan, B. M. Johnson, K. W. Jones, M. Meron
Electron Capture And Loss For 2.5-200-Mev 16s13++He Collisions, M. W. Clark, E. M. Bernstein, J. A. Tanis, W. G. Graham, Robert H. Mcfarland, T. J. Morgan, B. M. Johnson, K. W. Jones, M. Meron
Physics Faculty Research & Creative Works
Electron capture and loss cross sections have been measured for highly charged (q=13+) sulfur ions with energies 2.5-200 MeV colliding with helium. Electron capture varies by nearly six orders of magnitude over the energy range investigated, while electron loss varies by only about a factor of 2. The capture cross sections are in reasonable agreement with classical and empirical scaling rules, while the loss cross sections agree well with the plane-wave Born approximation. © 1986 The American Physical Society.
V/2 Electrons In H++H Ionizing Collisions, Ronald E. Olson
V/2 Electrons In H++H Ionizing Collisions, Ronald E. Olson
Physics Faculty Research & Creative Works
Classical-trajectory Monte Carlo calculations are used to determine the velocity and angular dependence of the electron ionized in the H++HH++H++e- collision. The energy range studied is 40200 keV. At energies E60 keV, ionized electrons with velocities that are near one-half (v/2) the relative velocity v of the collision dominate the electron spectra. At higher energies the maximum position of the ionized electrons shifts and is found centered about the target nucleus. © 1986 The American Physical Society.
Resonant Charge Transfer In Symmetric Alkali-Ion Alkali-Atom Collisions, F. K. Men, M. Kimura, Ronald E. Olson
Resonant Charge Transfer In Symmetric Alkali-Ion Alkali-Atom Collisions, F. K. Men, M. Kimura, Ronald E. Olson
Physics Faculty Research & Creative Works
Resonant charge transfer in alkali-ion alkali-atom collisions is investigated by using the molecular-orbital expansion method incorporating the use of electron translation factors. Molecular wave functions and eigen energies are obtained by the pseudopotential method. Molecular properties, Re, De, and e, obtained in the present calculation are in good accord with other recent theoretical results, as well as spectroscopic measurements. Three-state close-coupling calculations reproduce the positions of the maxima and minima in the oscillatory structure seen experimentally in the resonant-charge-transfer cross sections for the Li2 + and Cs2 + systems. The magnitude of the total cross sections and their velocity dependence …
Ionization Of H And He+ By Electrons And Positrons Colliding At Near-Threshold Energies, A. E. Wetmore, Ronald E. Olson
Ionization Of H And He+ By Electrons And Positrons Colliding At Near-Threshold Energies, A. E. Wetmore, Ronald E. Olson
Physics Faculty Research & Creative Works
Ionization cross sections for the four combinations of electrons and positrons on H and He+ have been calculated at energies near the threshold for ionization using the classical trajectory Monte Carlo method. In addition, charge-exchange (positronium formation) cross sections have been calculated for the positron-impact collisions. The ionization cross sections compare well with the predictions of the Wannier and Klar models and experimental observations. Our results indicate that the Wannier-type threshold behavior may extend to higher energies than was previously thought. In addition, we have calculated two of the collision parameters, the angle and the relative separation between the escaping …