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Physics Faculty Research & Creative Works

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Articles 1351 - 1380 of 1762

Full-Text Articles in Physical Sciences and Mathematics

Classical Calculation Of High-Energy Electron Capture In 5-Mev Proton-Hydrogen Collisions, D. R. Schultz, C. O. Reinhold, Ronald E. Olson Jan 1992

Classical Calculation Of High-Energy Electron Capture In 5-Mev Proton-Hydrogen Collisions, D. R. Schultz, C. O. Reinhold, Ronald E. Olson

Physics Faculty Research & Creative Works

The existence of the classical Thomas peak in the angular distribution of projectiles undergoing capture in collisions of 5-MeV protons with atomic hydrogen is explored using the three-body, three-dimensional classical-trajectory Monte Carlo technique. A method that selects only that portion of the initial phase space which yields capture at this energy was developed to make the calculation tractable due to the extremely small cross section. The spectrum obtained displays only a small shoulder near the angle predicted by Thomas on the basis of successive classical binary collisions and the total (integral) cross section is overestimated by a factor of 26 …

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Homogeneous Nucleation Of Liquid From The Vapor Phase In An Expansion Cloud Chamber, John L. Schmitt Jan 1992

Homogeneous Nucleation Of Liquid From The Vapor Phase In An Expansion Cloud Chamber, John L. Schmitt

Physics Faculty Research & Creative Works

A Wilson expansion cloud chamber has been used to measure the homogeneous vapor-to-liquid nucleation of several materials over the past decade. These data, representing nucleation rate as a function of temperature and supersaturation ratio for toluene, nonane, and water measured in our center, have been re-examined and are presented both in graphical form and as a table of selected data points. The latter is included for ease of comparison with theory. Measurements of the binary homogeneous nucleation of ethanol-water (E-W) mixtures are also presented. The expansion chamber experimental technique and data reduction technique are discussed.

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Differential Cross Sections For State-Selective Electron Capture In 25100-Kev Proton-Helium Collisions, D. R. Schultz, C. O. Reinhold, Ronald E. Olson, D. G. Seely Jan 1992

Differential Cross Sections For State-Selective Electron Capture In 25100-Kev Proton-Helium Collisions, D. R. Schultz, C. O. Reinhold, Ronald E. Olson, D. G. Seely

Physics Faculty Research & Creative Works

Cross sections differential in the scattering angle of the projectile are presented for electron capture summed over all states and to the 2s, 2p, 3s, 3p, 4s, and 4p states of hydrogen in 25-, 50-, and 100-keV proton-helium collisions. The classical-trajectory Monte Carlo (CTMC) technique was employed for these calculations as well as to compute total cross sections as a function of impact energy. The latter are compared with experiment to display the behavior of the integral state-selective cross sections in this energy regime. Detailed comparison is also made between the calculated angular differential cross sections and the experimental measurements …

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Collisional Redistribution Of Polarized Radiation For Sr-Ar(He) Systems: A Numerical Comparison Of The Semiclassical Decoupiing/Locking Model To Exact Results, Ronald James Bieniek, Paul S. Julienne, Rank Rebentrost Dec 1991

Collisional Redistribution Of Polarized Radiation For Sr-Ar(He) Systems: A Numerical Comparison Of The Semiclassical Decoupiing/Locking Model To Exact Results, Ronald James Bieniek, Paul S. Julienne, Rank Rebentrost

Physics Faculty Research & Creative Works

Abstract Semiclassical formulations of collisional redistribution of polarized radiation are presented at several levels of approximation, from full classical path coupled equations to the backing/decoupling model. These are numerically tested against the results of a quantum mechanical coupled-channels formalism, by the comparison of polarization curves in both spectral wings of the Srf1 So-1 Pi) transition, with Ar and He as collisional perturbers. It is found that the locking/decoupling model can often produce good agreement with exact results if the effects due to trajectories and multiple Condon points are treated properly. Significant discrepancies due to the Condon approximation used ty the …

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Binary Peak Enhancement And Structure In Partially Stripped Ion-Atom Collisions, D. R. Schultz, Ronald E. Olson Aug 1991

Binary Peak Enhancement And Structure In Partially Stripped Ion-Atom Collisions, D. R. Schultz, Ronald E. Olson

Physics Faculty Research & Creative Works

Recent experiments have found both an unexpected enhancement and structure of the binary peak in the spectrum of electrons ejected in partially stripped ion-atom collisions. Utilizing the theoretical approach which has been used to elucidate the origin of this behavior, a survey of their manifestation is presented over a broad range of nuclear and ionic charges (C, F, Fe, I and U ions) and impact energies (0.1 to 100 MeV u-1). For forward binary electron emission it is shown that the greatest enhancement occurs for the lowest projectile ion charge states (highly screened nuclei). The magnitude of the enhancement maximizes …

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X-Ray Emission From Slow Highly Charged Ar Ions Interacting With A Ge Surface, Michael Schulz, C. Lewis Cocke, Siegbert Hagmann, Martin P. Stockli, Horst Schmidt-Bocking Aug 1991

X-Ray Emission From Slow Highly Charged Ar Ions Interacting With A Ge Surface, Michael Schulz, C. Lewis Cocke, Siegbert Hagmann, Martin P. Stockli, Horst Schmidt-Bocking

Physics Faculty Research & Creative Works

We have measured K x-ray spectra and yields from Ar17+ ions slowly approaching a single-crystal Ge surface. The yields were measured as a function of the projectile velocity component perpendicular to the surface. From the data a characteristic time of approximately 1 psec was extracted for the in-flight filling above the surface of the Ar K vacancy.

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Dielectronic Recombination On And Electron-Impact Excitation Of Heliumlike Argon, Rami M. Ali, Chander P. Bhalla, C. Lewis Cocke, Michael Schulz, Martin P. Stockli Jul 1991

Dielectronic Recombination On And Electron-Impact Excitation Of Heliumlike Argon, Rami M. Ali, Chander P. Bhalla, C. Lewis Cocke, Michael Schulz, Martin P. Stockli

Physics Faculty Research & Creative Works

We have measured cross sections for Δn=1 dielectronic recombination (DR) on He-like argon and found good agreement with theoretical calculations based on the Hartree-Fock atomic model. Experimental absolute cross sections were obtained by using the electron-energy dependence of yields of He-like and Li-like argon ions from the Kansas State University electron-beam ion source to measure the ratio of the DR cross section on He-like argon to the electron-impact-ionization cross section of Li-like argon and normalizing to the latter. The K x-ray emission spectra due to Δn=1,2 DR and n=1→2 electron-impact excitation of He-like argon were also observed with a Si(Li) …

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Abnormal Behaviour Of Zero Degree Δ-Electron Emission On The Projectile Ionic Charge, O. Jagutzkit, S. Hagtnanni, H. Schmidt-Bockingt, Ronald E. Olson, D. R. Schultz, R. Dornert, R. Kocht, A. Skutlartz, A. González, T. B. Quinterosi, C. Kelbcht, P. Richardt May 1991

Abnormal Behaviour Of Zero Degree Δ-Electron Emission On The Projectile Ionic Charge, O. Jagutzkit, S. Hagtnanni, H. Schmidt-Bockingt, Ronald E. Olson, D. R. Schultz, R. Dornert, R. Kocht, A. Skutlartz, A. González, T. B. Quinterosi, C. Kelbcht, P. Richardt

Physics Faculty Research & Creative Works

The 0° δ-electron emission was investigated by an electron-projectile coincidence technique as a function of incoming and outgoing projectile charge state for 0.53 MeV u-1Cuq+ on He. The electron emission spectra vary strongly with initial and final projectile charge state. For pure ionization channels the cross sections follow for low electron energy the q2-scaling law whereas in the binary encounter regime the scaling is reversed. Ctmc calculations are in fair agreement with the experimental data. © 1991 IOP Publishing Ltd.

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Population Of Highly Excited Intermediate Resonance States By Electron Transfer And Excitation, Reinhold S. Schuch, Edson L B Justiniano, Michael Schulz, Sheldon Datz, Peter F. Dittner, J. P. Giese, Herbert F. Krause, Harald Schone, Charles Randy Vane, Stephen M. Shafroth May 1991

Population Of Highly Excited Intermediate Resonance States By Electron Transfer And Excitation, Reinhold S. Schuch, Edson L B Justiniano, Michael Schulz, Sheldon Datz, Peter F. Dittner, J. P. Giese, Herbert F. Krause, Harald Schone, Charles Randy Vane, Stephen M. Shafroth

Physics Faculty Research & Creative Works

Coincidences between two sulfur K x rays were detected from collisions of hydrogenlike S ions with H2 gas in the projectile energy range between 150 and 225 MeV. These K x rays are emitted in the decay of doubly excited states formed in the collisions via transfer and excitation. The excitation function for two coincident Kβ transitions peaks at about 175 MeV, slightly above the expected KMM resonance energy for resonant transfer and excitation (RTE). This demonstrates the occurrence of ΔN≥2 transitions (i.e., KMM and higher resonances) in the RTE process. The cross sections for the population of the …

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Intraconfiguration Interactions In Barium 6p1/2Nf Autoionizing States, Xiao Wang, J. Greg Story, William E. Cooke Apr 1991

Intraconfiguration Interactions In Barium 6p1/2Nf Autoionizing States, Xiao Wang, J. Greg Story, William E. Cooke

Physics Faculty Research & Creative Works

Measurements are reported of the energies and linewidths of the J=2, 3, and 4 components of the 6p1/214f and 6p1/219f states of barium. These states are anomalously broad, having autoionization lifetimes of approximately 1/2 of a classical Rydberg orbit period, and previously measurements have discerned no differences among the various J components. This work shows that the differences can be observed, and are consistent with calculations. The variations between states would be large if the states were LS coupled, but the large 6p ionic fine-structure forces recoupling into jj configurations. The spherical symmetry of the 6p …

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Realization Of A Measurement Of A Weak Value, N. W M Ritchie, J. Greg Story, Randall G. Hulet Mar 1991

Realization Of A Measurement Of A Weak Value, N. W M Ritchie, J. Greg Story, Randall G. Hulet

Physics Faculty Research & Creative Works

We present the first realization of a measurement of a weak value, a concept recently introduced by Aharonov, Albert, and Vaidman (AAV). Our experiment uses a birefringent crystal to separate the two linear-polarization components of a laser beam by a distance small compared to the laser-beam waist. This weak measurement is followed by a strong measurement which translates the centroid of the beam by a distance far larger than the birefringence-induced separation. In addition, we present data corresponding to orthogonal initial and final states, for which the weak value is not defined. This interference effect may have application in the …

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Recent Advances In The Comparison Of Matter— And Antimatter—Atom Collisions, D. R. Schultz, Ronald E. Olson, C. O. Reinhold Feb 1991

Recent Advances In The Comparison Of Matter— And Antimatter—Atom Collisions, D. R. Schultz, Ronald E. Olson, C. O. Reinhold

Physics Faculty Research & Creative Works

The relatively recent advent of low energy antimatter projectiles has spurred a rapid advance in the comparison of matter- and antimatter-atom collisions. These experimental studies have in turn stimulated a great deal of theoretical effort to explain their results, and together both theory and experiment have shed new light on the dynamics of ion-atom collisions. Here we review these developments with particular emphasis on the processes of ionization and charge transfer. © 1991 IOP Publishing Ltd.

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Effects Of Sample Orientation On The Corrosion Of Zinc In Ammonium Sulfate And Sodium Hydroxide Solutions, D. Abayarathna, Edward Boyd Hale, Thomas J. O'Keefe, Y. M. Wang, D. Radovic Jan 1991

Effects Of Sample Orientation On The Corrosion Of Zinc In Ammonium Sulfate And Sodium Hydroxide Solutions, D. Abayarathna, Edward Boyd Hale, Thomas J. O'Keefe, Y. M. Wang, D. Radovic

Physics Faculty Research & Creative Works

The corrosion and electrochemical properties of three zinc single crystal surfaces with different orientations have been investigated. In near-neutral 1 M (NH4)2SO4, the corrosion rates on all three surfaces were found to be similar. However, the SEM morphologies of the corresponding corroded surfaces were markedly different from each other, but consistent with preferential attack of {1120} surfaces. In alkaline 0.5 N NaOH solution, the three sample orientations showed significantly different reactivities, with the (1120) surface exhibiting the highest reactivity and corrosion rate. Here, passivation ultimately occurred and the difference in the corrosion performance of …

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Quantum Interference In Clothed-Ion-Atom Binary Peak Structures, C. O. Reinhold, D. R. Schultz, Ronald E. Olson, C. Kelbch, R. Koch, H. Schmidt-Böcking Jan 1991

Quantum Interference In Clothed-Ion-Atom Binary Peak Structures, C. O. Reinhold, D. R. Schultz, Ronald E. Olson, C. Kelbch, R. Koch, H. Schmidt-Böcking

Physics Faculty Research & Creative Works

An impulse approximation for ionizing collisions of clothed ions with atoms is used to explain the origin of an anomalous oscillation in the ejected electron spectrum in the region of the binary peak. In addition, measurements which evidence this feature for 1-MeV/u U21+ ions colliding with helium are presented. It is shown that this behavior arises from interference structures in the elastic differential cross section for the scattering of target electrons from the impinging ion and that it is associated with the well-known phenomenon of rainbow scattering. © 1991 The American Physical Society.

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Feq⁺+ H, H2and He Electron Loss And He2++ H(N = 1, 2) Electron Capture Cross Sections: Processes Of Interest In Fusion Plasmas, D. R. Schultz, L. Meng, C. O. Reinhold, Ronald E. Olson Jan 1991

Feq⁺+ H, H2and He Electron Loss And He2++ H(N = 1, 2) Electron Capture Cross Sections: Processes Of Interest In Fusion Plasmas, D. R. Schultz, L. Meng, C. O. Reinhold, Ronald E. Olson

Physics Faculty Research & Creative Works

Cross sections have been calculated utilizing the classical trajectory Monte Carlo method for collisional processes of special interest to plasma fusion research. Specifically, H1H2and He total electron loss cross sections for the impact by Feq+(1 < q < 26) impurity ions, in the energy range of 50 to 500keV/u, are presented. These results illustrate a clear departure for low charge states (q < 10) from scaling of the cross section with projectile charge (q). Further, cross sections for electron capture from both the ground and n = 2 states of H by 30 to lOOkeV/u He2+impact are tabulated as function of final n-level, yielding information for neutral beam heating models. © 1991 IOP Publishing Ltd.

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Projectile- And Target-Charge Dependent Effects In Ionizing Collisions Of H ⁺ And He 2+ With He, Ne And Ar Atoms, Timothy James Gay, M. W. Gealy, M. E. Rudd Dec 1990

Projectile- And Target-Charge Dependent Effects In Ionizing Collisions Of H ⁺ And He 2+ With He, Ne And Ar Atoms, Timothy James Gay, M. W. Gealy, M. E. Rudd

Physics Faculty Research & Creative Works

The spectra of electrons emitted in collisions between H + and He 2+ projectiles and He, Ne and Ar targets at energies of 50 and 100 keV amu -1 have been studied. The data are in qualitative agreement with results of Irby el al., but are in disagreement with measurements of Bernardi et al. It is shown that the observed electron spectra have a dependence on both target-ion and projectile effective charge that can be understood qualitatively in terms of 'saddle-point' ionization. Several issues relevant to saddle-point ionization are discussed. © 1990 IOP Publishing Ltd.

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Uniform Stationary-Phase Methods For Energy Spectra Resulting From Collisions In A Complex Potential: Penning And Associative Ionization Of He*(2³S)+He*(23s), Ronald James Bieniek, M. W. Muller, M. Movre Dec 1990

Uniform Stationary-Phase Methods For Energy Spectra Resulting From Collisions In A Complex Potential: Penning And Associative Ionization Of He*(2³S)+He*(23s), Ronald James Bieniek, M. W. Muller, M. Movre

Physics Faculty Research & Creative Works

Heavy-particle collisions involving strong electronic coupling can be conveniently described by using a complex (optical) potential in the entrance channel. Uniform JWKB stationary-phase techniques are used to evaluate T-matrix elements for transitions where an electron is ejected. The semi-analytic expressions for the resulting electron energy spectra are no more difficult to implement than corresponding ones for totally real potentials. Numerical results are reported for Penning and associative ionization from sub thermal He*(23S)+He*(23S) collisions. These are in excellent agreement with fully quantal, complex-potential computations. The stationary-phase expressions for T-matrix elements and differential cross sections are employed to elucidate the rapid and …

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Tunable Lasers At 1080 Nm For Helium Optical Pumping, Laird D. Schearer, Padetha Tin Dec 1990

Tunable Lasers At 1080 Nm For Helium Optical Pumping, Laird D. Schearer, Padetha Tin

Physics Faculty Research & Creative Works

We describe the current status of tunable, cw, solid-state lasers in the infrared region of the spectrum which may be tuned to the helium resonance transition near 1083 nm. The principal use for these laser devices is the optical pumping of 3He and 4He atoms via the 23S1 metastable state. The tunable lasers we have examined include Nd3+-doped YAlO3, LaxNd1-xMgAl11O19 (x ∼0.15), Nd:LiNbO3, and Nd:silica glass fibers. Power outputs from these lasers range from a milliwatt to more than 1 W at …

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A High Power, Tunable, Arc-Lamp Pumped Nd-Doped Lanthanum-Hexaluminate Laser, Padetha Tin, Laird D. Schearer Dec 1990

A High Power, Tunable, Arc-Lamp Pumped Nd-Doped Lanthanum-Hexaluminate Laser, Padetha Tin, Laird D. Schearer

Physics Faculty Research & Creative Works

An LNA (Nd-doped lanthanum-hex aluminate) crystal has been pumped with a cw, krypton arc lamp in a commercial Nd:YAG cavity. The cw output power greater than 6 W is obtained in a 28-cm long, plane mirror cavity. The free-running wavelength is near 1083 nm and has a width of about 0.8 nm. Inserting a 0.25 mm thick, uncoated solid etalon in the cavity permits the laser output to be continuously tuned from 1082 to 1084 nm by tilting the etalon. The laser bandwidth is reduced to below 0.016 nm. Over 3 W are obtained at the helium resonance transition. The …

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Single Transfer-Excitation Resonance Observed Via The Two-Photon Decay In He-Like Ge³⁰⁺, Paul H. Mokler, S. Reusch, A. Warczak, Zbigniew Stachura, T. Kambara, Alfred K. Muller, Reinhold S. Schuch, Michael Schulz Dec 1990

Single Transfer-Excitation Resonance Observed Via The Two-Photon Decay In He-Like Ge³⁰⁺, Paul H. Mokler, S. Reusch, A. Warczak, Zbigniew Stachura, T. Kambara, Alfred K. Muller, Reinhold S. Schuch, Michael Schulz

Physics Faculty Research & Creative Works

We measured the 2E1 decay of the 1s2s 1S0 →1s2 1S0 transition in He-like germanium for 12- to 19-MeV/u Ge31+ +H2 collisions. The resonant population of the 2s2p 1P1 state by transfer excitation was isolated due to its cascading to the 1s2s 1S0 state. The experimental cross sections compare well with calculations using dielectronic recombination rates. The method gives the unique possibility to populate selectively the 1S0 state in heavy He-like ions.

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Electron Emission From Both Target And Projectile In C⁺ + He Collisions, C. O. Reinhold, D. R. Schultz, Ronald E. Olson, L. H. Toburen, R. (Robert) D. Dubois Dec 1990

Electron Emission From Both Target And Projectile In C⁺ + He Collisions, C. O. Reinhold, D. R. Schultz, Ronald E. Olson, L. H. Toburen, R. (Robert) D. Dubois

Physics Faculty Research & Creative Works

The first classical trajectory Monte Carlo calculation of the electronic spectra arising from both target and projectile ionization is presented and compared with experimental measurements of the differential cross section for electrons emitted in C++He collisions. The theoretical treatment is based on an independent-electron model in which the interactions between the electrons are approximated by quantum model potentials. Good agreement is obtained between theory and experiment and structures appearing in the measurements can be explained in terms of the electron emission from either, or both, target and projectile. Further, the relative importance of the electron capture to the continuum and …

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Coincident Charge State Production In F⁶⁺+Ne Collisions, D. R. Schultz, Ronald E. Olson, C. O. Reinhold Nov 1990

Coincident Charge State Production In F⁶⁺+Ne Collisions, D. R. Schultz, Ronald E. Olson, C. O. Reinhold

Physics Faculty Research & Creative Works

Total cross sections are presented for the production of various stages of multiple ionization of the target in coincidence with the final projectile charge state for collisions of F6+ with Ne at 10 and 15 MeV. In particular, the current measurements are compared with the results of a classical trajectory Monte Carlo method in which electrons are included explicitly on both target and projectile (nCTMC) and with those based on the conventional independent electron model (IEM). It is shown by the good agreement with experiment that the nCTMC model simultaneously represents well the ionization, charge transfer and excitation channels …

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Theoretical Description Of The Binary Peak In Clothed Ion-Atom Collisions, C. O. Reinhold, Ronald E. Olson Oct 1990

Theoretical Description Of The Binary Peak In Clothed Ion-Atom Collisions, C. O. Reinhold, Ronald E. Olson

Physics Faculty Research & Creative Works

The impulse or binary encounter approximation for ion-atom collisions is extended to treat the non-Coulomb interaction between a clothed projectile ion and the target electrons. This model is shown to reproduce the unexplained enhancement of the zero-degree binary peak for partially stripped ions over that for Equi velocity fully stripped ions that has recently been observed experimentally in Fq++H2, He collisions. Very good agreement is obtained between theory and experiment and, furthermore, this model is used to illuminate the underlying dynamics which leads to the observed enhancement. © 1990 IOP Publishing Ltd.

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Angular Distribution Of Auger Electrons Emitted Through The Resonant Transfer And Excitation Process Following O⁵⁺+He Collisions, Malika Benhenni, Stephen M. Shafroth, J. K. Swenson, Michael Schulz, J. P. Giese, Harald Schone, Charles Randy Vane, Peter F. Dittner, Sheldon Datz Oct 1990

Angular Distribution Of Auger Electrons Emitted Through The Resonant Transfer And Excitation Process Following O⁵⁺+He Collisions, Malika Benhenni, Stephen M. Shafroth, J. K. Swenson, Michael Schulz, J. P. Giese, Harald Schone, Charles Randy Vane, Peter F. Dittner, Sheldon Datz

Physics Faculty Research & Creative Works

This Letter reports the first measurements of the angular distribution of Auger electrons emitted from the decay of the (1s2s2p2)3D O4+** doubly excited state formed predominantly through resonant transfer and excitation (RTE) in collisions of 13-MeV O5+ projectiles with He. The (1s2s2p2)3D angular distribution is strongly peaked along the beam direction, in agreement with recent calculations of the RTE angle-dependent impulse approximation. Furthermore, interference effects between the RTE and the elastic target direct-ionization channels are observed.

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Double Excitation Of He By Fast Ions, J. P. Giese, Michael Schulz, J. K. Swenson, Harald Schone, Malika Benhenni, S. L. Varghese, Charles Randy Vane, Peter F. Dittner, Stephen M. Shafroth, Sheldon Datz Aug 1990

Double Excitation Of He By Fast Ions, J. P. Giese, Michael Schulz, J. K. Swenson, Harald Schone, Malika Benhenni, S. L. Varghese, Charles Randy Vane, Peter F. Dittner, Stephen M. Shafroth, Sheldon Datz

Physics Faculty Research & Creative Works

Autoionization of He atoms following double excitation by electrons, protons, CQ+ (Q=4-6), and FQ+ (Q=7-9) ions has been studied. The electron-emission yields from the doubly excited 2s2(1S), 2s2p(1P), and 2p2(1P) states were measured at the reduced projectile energy of 1.5 MeV/nucleon for observation angles between 10°and 60°. The results indicate excitation to the 2s2(1S) and 2p2(1D) states increases as approximately Q3, while excitation to the 2s2p(1P) state varies as approximately Q2, where Q is …

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Observation Of Velocity-Tuned Multiphoton Doppleron Resonances In Laser-Cooled Atoms, Jeffrey J. Tollett, Jian Chen, J. Greg Story, N. W M Ritchie, Curtis C. Bradley, Randall G. Hulet Jul 1990

Observation Of Velocity-Tuned Multiphoton Doppleron Resonances In Laser-Cooled Atoms, Jeffrey J. Tollett, Jian Chen, J. Greg Story, N. W M Ritchie, Curtis C. Bradley, Randall G. Hulet

Physics Faculty Research & Creative Works

An atomic beam of Li was transversely cooled using an intense standing-wave radiation field. A dramatic change in the transverse velocity distribution was observed. Structure in the resulting velocity distribution was found to be due to velocity-tuned multiphoton Doppleron resonances. The force due to seven-photon resonances is clearly resolved in the data. The data are in good agreement with theoretical predictions.

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Rotational Effects In The Vuv Continuum Of H2, H. Schmoranzer, T. Noll, T. Noll, E. Roueff, H. Abgrall, Ronald James Bieniek Jun 1990

Rotational Effects In The Vuv Continuum Of H2, H. Schmoranzer, T. Noll, T. Noll, E. Roueff, H. Abgrall, Ronald James Bieniek

Physics Faculty Research & Creative Works

The effects of rotation-vibration interaction and of rotational coupling between the B 2p 1Σu+ and C 2p 1Πu electronic states on the B-X continuum of H2 were investigated spectroscopically using monochromatized synchrotron radiation for selective excitation of rovibronic states. The perturbed continuum intensities observed for the first time agree well with close-coupling calculations also performed. © 1990 IOP Publishing Ltd.

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Coupled-Channel Optical Calculation Of Electron-Hydrogen Scattering: The Distorted-Wave Optical Potential, Igor Bray, Don H. Madison, Ian E. Mccarthy Jun 1990

Coupled-Channel Optical Calculation Of Electron-Hydrogen Scattering: The Distorted-Wave Optical Potential, Igor Bray, Don H. Madison, Ian E. Mccarthy

Physics Faculty Research & Creative Works

The coupled-channel optical method solves a set of coupled momentum-space integral equations for a finite set of reaction channels. The remaining channels, including the target continuum, are described by the polarization potential operator, which formally depends on the full three-body state vectors for these channels. The distorted-wave optical potential makes the distorted-wave Born approximation for these state vectors, using exact target states. No other approximation is made. Calculations and comparison with experiment are reported for total ionization cross sections and asymmetries, total excitation cross sections, entrance-channel phenomena, and the coupled 1s,2s,2p channels, at a range of energies.

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Effect Of Second-Order Exchange In Electron-Hydrogen Scattering, Don H. Madison, Igor Bray, Ian E. Mccarthy May 1990

Effect Of Second-Order Exchange In Electron-Hydrogen Scattering, Don H. Madison, Igor Bray, Ian E. Mccarthy

Physics Faculty Research & Creative Works

The electron-hydrogen scattering problem has been a nemesis to theoretical atomic physicists due to the fact that even the most sophisticated of theoretical calculations, both perturbative and nonperturbative, do not agree with experiment. The current opinion is that the perturbative approach cannot be used for this problem since recent second-order calculations are not in agreement with the experimental data and higher-order calculations are deemed impractical However, these second-order calculations neglected second-order exchange. We have now added exchange to the second-order calculation and have found that the primary source of disagreement between experiment and theory for intermediate energies is attributable not …

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Subshell Electron Capture In Collisions Of Fully Stripped Ions With He And H2 At Intermediate Energies, L. Meng, C. O. Reinhold, Ronald E. Olson Jan 1990

Subshell Electron Capture In Collisions Of Fully Stripped Ions With He And H2 At Intermediate Energies, L. Meng, C. O. Reinhold, Ronald E. Olson

Physics Faculty Research & Creative Works

Classical phase-space models of the hydrogen molecule and helium are utilized to study shell and subshell electron-capture processes in collisions of fully stripped ions on charge states from 1 to 15 with H2 and He at intermediate impact energies (20200 keV/amu). Autoionization after double electron capture is approximated and is found to be an important channel for high projectile charges. The resulting (n,l) distributions for proton impact of He and H2 as well as total capture cross sections are found to be in very good agreement with experimental data. l distributions for high projectile charges are also analyzed for …

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