Digital Commons Network^™

Universal Stationary-Phase Treatment Of Far-Wing And Excimer Spectral Line Shapes, Ronald James Bieniek, T. J. Streeter

Physics Faculty Research & Creative Works

When two atoms are in proximity, their resonance lines are broadened because of the formation of molecular potentials, between which photon transitions can occur. The level of experimental refinement in measuring excimer and collisional far-wing spectra calls for interpretive theoretical methods that accurately treat the observed structure in line shapes. Of particular interest are satellites and undulations, for they can give much information on intermolecular potentials. We derive an expression for T-matrix elements, based on JWKB wave functions and stationary-phase techniques, that is universally applicable to situations with one, two, or more Condon points. Each transition point is treated individually, …

Ion Scattering From State-Selected Rydberg Atoms, G. A. Kohring, A. E. Wetmore, Ronald E. Olson

Physics Faculty Research & Creative Works

Classical-trajectory Monte Carlo calculations have been performed for collisions of protons with state-selected hydrogenic Rydberg atoms. The examples investigated were Rydberg atoms in the n=10, l=9 level with ml=0 and 9. The collision velocity range was 0.1 to 1.0 a.u. (2.2x107 to 2.2x108 cm/s). The ionization cross sections were found to be relatively insensitive to changes in the ml levels. However, the charge-transfer cross sections showed considerable enhancement if the Rydberg electron is orientated in a plane which is parallel to the direction of the incident projectile. © 1983 The American Physical Society.

Homogeneous Nucleation Of Toluene, John L. Schmitt, R. A. Zalabsky, G. W. Adams

Physics Faculty Research & Creative Works

The authors have used a fast expansion chamber to measure the homogeneous nucleation rate of toluene as a function of temperature and supersaturation. The measured nucleation rate ranges from 102 to 105 drops/cm3 s over a temperature range of 215-267 K. The measurements are compared with the "classical" nucleation theory and with the RKC theory. The inclusion of the RKC replacement factor brings the data into good agreement with theory using physically realistic values of the surface tension and the sticking coefficient. An empirical curve fit to the data is presented as well as a full listing of the thermodynamic …

New Relativistic Paradoxes And Open Questions, Florentin Smarandache

Branch Mathematics and Statistics Faculty and Staff Publications

Following the Special Theory of Relativity, Florentin Smarandache generalized the Lorentz Contraction Factor to an Oblique-Contraction Factor, which gives the contraction factor of the lengths moving at an oblique angle with respect to the motion direction. He also proved that relativistic moving bodies are distorted, and he computed the Angle-Distortion Equations.

He then showed several paradoxes, inconsistencies, contradictions, and anomalies in the Theory of Relativity.

According to the author, not all physical laws are the same in all inertial reference frames, and he gives several counter-examples. He also supports superluminal speeds, and he considers that the …

Flat Plate Solar Thermal Collectors: A Comparison Of Efficiencies Of Various Collector Configurations, Rudolph J. Eichenberger

Journal of the Arkansas Academy of Science

No abstract provided.

Stopping Power Of K Electrons At Extreme Relativistic Energies, P.T. Leung, M. L. Rustgi

Physics Faculty Publications and Presentations

The recent work of Anholt (1979) on K-vacancy production by relativistic projectiles has been applied to calculate the stopping power of the K electrons. The results show that for protons of energy ~10³ GeV and heavy target elements, the relativistic contributions to the stopping power amount to several times the results due to the longitudinal terms obtained from Walske's (1956) work.

Observation Of Biexcitonic Optical Bistability And Optical Limiting In Cucl, N. Peyghambarian, H. M. Gibbs, M. C. Rushford, D. A. Weinberger

Physics: Faculty Publications

Experimental evidence for the occurrence of optical bistability using the biexciton two-photon resonance in CuCl is presented. These observations agree with recent theoretical predictions that require an intensity of 10 MW/cm2 and 10-μm-thick etalons with 90% reflective coatings. Earlier much less demanding predictions neglected two important physical effects: unsaturable background absorption at the biexciton from the tail of the exciton resonance and broadening of the biexciton resonance with intensity.

Application Of The Impact Approximation To Collisional Line Shifts In Na-Rare Gas Systems, Mahdi Azougui

Masters Theses

"This dissertation deals, mainly, with the line shifts of the excited atoms of sodium induced by collisions with argon atoms. The general work is based on the study of both, broadenings of the lines and line shifts with a particular emphasis on the latter. A review is given for the case of very large principal quantum numbers N; then the binary collision method is detailed for low transitions (N ≤ 6) where the computed values are in very good agreement with the experimental results obtained by Krebs and Schearer.¹ This method breaks down at larger N. Next, a modification …

Theoretical Studies Of Water On Substrates, Sergio M. Terrazas

Doctoral Dissertations

"Model interaction potentials for H₂O on a basal f)-silver iodide substrate containing two types of defects, a potassium impurity and a four atomic layer ledge, are used to calculate optimal binding energy contours for the adsorbed H₂O molecule. (J. Phys. Chern. 84, 1473(1980)). The model substrate with the potassium impurity appears to increase the optimal binding energy at the preferred adsorption sites to 23 kcal/rnol -- a value approximately 40 % larger than the maximal binding energy sites on the defect-free model silver-exposed basal plane of AgI. The impurity also distorts the hexagonal symmetry of the …

Homogeneous Nucleation Of Nonane In Argon Using An Expansion Cloud Chamber, Gregg Wesley Adams

Doctoral Dissertations

"The homogeneous nucleation rate of nonane has been measured using an expansion cloud chamber. Data were obtained for pre-expansion temperatures of 45°C, 35°C, 25°C, 15°C, 5°C, and -5°C. The measured nucleation rate ranges from 10² to 10⁵ drops/cm³ -sec over a temperature range of 216 K to 270 K. The data set is sufficiently extensive to provide a detailed test for nucleation theories applied to nonane. The measured rates are compared with the "classical" nucleation theory and with a modified classical theory using the replacement factor of Reiss, Katz and Cohen (RKC). It is found that neither …

Collisions Of Fast Highly Charged Ions In Gas Targets: Ionization, Recoil-Ion Production, And Charge Transfer, A. S. Schlachter, K. H. Berkner, H. F. Beyer, W. G. Graham, W. Groh, R. Mann, A. Müller, Ronald E. Olson, R. V. Pyle, J. W. Stearns, J. A. Tanis

Physics Faculty Research & Creative Works

Electron-capture, ionization, and recoil-ion-production cross-sections are measured and calculated for fast highly charged projectiles in hydrogen and rare-gas targets. Recoil-ion-production cross-sections are found to be large; the low energy and high charge states of the recoil ions make them useful for subsequent collision studies. © 1983 IOP Publishing Ltd.

Thermal Decomposition Kinetics Of Iodine‐Doped Polyacetylene In Vacuum, J. ‐E Osterholm, H. Yasuda, L. L. Levenson

Physics Faculty Research & Creative Works

The thermal stability of iodine‐doped polyacetylene films, (CHIy)x, has been studied by means of electrical conductivity measurements, measurements on weight loss, and mass spectrometric analysis of desorbing species. When heated between room temperature and 125°C in vacuum, these films proved to be of poor thermal stability, being unstable at temperatures above 20°C. During the thermal treatments, molecular iodine desorbs from the films, resulting in an appreciable dopant weight loss with accompanying decrease in the electrical conductivity. The decomposition process does not follow simple kinetics. Copyright © 1983 John Wiley & Sons, Inc.

Ion-Atom Differential Cross Sections At Intermediate Energies, Ronald E. Olson

Physics Faculty Research & Creative Works

The classical-trajectory Monte Carlo method has been used to calculate H++H(1s) electron-capture and ionization differential cross sections in the range 25-200 keV. The results indicate the importance of including excited product states to describe the small-angle electron-capture scattering. Angular scattering of the electron removed by the ionization process has been studied as a function of ejected-electron velocity ve. The classical calculations are in reasonable agreement with coupled-channel results of Shakeshaft [Phys. Rev. A 18, 1930 (1978)] as to the "electron capture to the continuum" (ECC) component of the ionization process where this term is defined as the ejected electron being …

Vibrational-Rotational Deexcitation Of Hf In Collision With He, Ronald James Bieniek

Physics Faculty Research & Creative Works

State-to-state cross sections are reported for vibrational-rotational transitions for HF in collisions with He, at collisional energies of 0.5 and 1.0 eV. These were computed within the infinite-order sudden (IOS) approximation using adiabatic, distorted-wave techniques. Values are tabulated for the vibrational-rotational deexcitation sequences (v,j)→(v-1, 0), with v=1, 2, 3, 4 and j=0-40. These quenching cross sections can be used in conjunction with IOS factorization formulas to compute VRT cross sections for final rotational states other jf=0. In addition to IOS results, vibrational quenching cross sections were computed using the much more simple breathing-sphere technique. The breathing-sphere results compare favorably to …

Molecular Treatment Of Charge Transfer In Li+ +Ca Collisions, M. Kimura, H. Sato, Ronald E. Olson

Physics Faculty Research & Creative Works

The perturbed-stationary-state method, appended with electron translation factors, has been applied to charge transfer in Li+ +Ca collisions for energies from 0.1 to 20 keV/amu. The Born-Oppenheimer wave functions and eigenvalues were generated using the pseudopotential technique, which reduced the many-electron system to a simpler two-electron problem. The molecular ground-state X +1 is calculated to be bound and has the potential-well parameters Re=6.20a0, De=1.11 eV, e=235 cm-1, and Be=0.263 cm-1. From the scattering computations, a representative value for the charge-transfer cross section is 4x10-15 cm2 at 5 keV/amu. The cross section decreases rapidly as the energy is reduced below 1 …

Intermolecular Interactions For Phosphatidyl Choline And Phosphatidyl Ethanolamine, Tony Flaim, Stig Friberg, Patricia L.M. Plummer

Chemistry Faculty Research & Creative Works

Intermolecular interaction between pairs of methylphosphocholine (MPC) and methylphosphoethanolamine were calculated using an extended CNDO/2 program. Experimentally determined conformations were used for the ethanolamine and choline groups. In the methylphosphocholine the major interaction was intramolecular, involving the phosphate ester-choline groups, while in the ethanolamine the maximum attraction was intermolecular between the ethanolamine and the phophate ester of a neighboring molecule(s). © 1983.

On The Schrödinger Spin‐Exchange Ferromagnet, Harry A. Brown

Physics Faculty Research & Creative Works

The thermodynamic behavior of a ferromagnet whose interactions are described by the Schrödinger spin‐exchange operator is investigated. The transition temperatures, magnetization, susceptibility, exchange energy, heat capacity, and entropy are calculated for general spin and lattice coordination number using the constant‐coupling approximation. Both first‐ and second‐order phase transitions are found. Comparison with some results of the high‐temperature expansion method shows some qualitative agreement. Copyright © 1983 WILEY‐VCH Verlag GmbH & Co. KGaA

Nanosecond Optical Transmission Studies Of Laser Annealing In Ion-Implanted Silicon-On-Sapphire, M. C. Lee, H. W. Lo, A. Aydinli, G. J. Trott, A. Compaan, Edward Boyd Hale

Physics Faculty Research & Creative Works

Time-resolved optical transmission has been studied using 633 and 514 nm CW probes on ion-implantation-amorphized silicon-on-sapphire during annealing by a 10 nsec, ⊥ J/cm2 pulse at either 532 nm or 485 nm. As recrystallization sets in the transmitted signal at 514 nm rises by ⊥ 103 in ⊥ 60 nsec and provides a measure of regrowth velocity. Beyond 200 nsec the much slower transmission rise is used to provide an estimate of the Si cooling rate. The difference in transmission observed between initially crystalline and initially amorphous Si provide an estimate of the latent heat of recrystallization of the amorphous …

Evidence For Coupling Of Velocity And Composition Fluctuations In A Binary Liquid Mixture, James V. Maher, Nalini Easwar, W. I. Goldburg, M. Joshua

Physics: Faculty Publications

A critical mixture of isobutyric acid and water was quenched from the one-phase region into the two-phase region and, after the spinodal ring was well developed, a reverse quench returned the system to the one-phase region. Light-scattering measurements for this process exhibit a clearly nondiffusive relaxation which, at least for early times after the quench reversal, is in good agreement with Ruiz's scheme for the coupling of velocity and composition fluctuations.

Positive Identification Of The Cr(4+)-->Cr(3+) Thermal Transition In Gaas, David C. Look, S. Chaudhuri, L. Eaves

Physics Faculty Publications

Temperature-dependent Hall-effect measurements on two Cr-doped GaAs samples
show a dominant center at E₁ =0.324—1.4 x 10^-4T eV, with respect to the valence-band edge. By comparison with secondary-ion mass spectroscopy measurements of the Cr concentration, and recent EPR measurements of the Cr²⁺, Cr³⁺, and Cr⁴⁺ concentration in several samples, it is shown unambiguously that this energy describes the Cr⁴⁺→Cr³⁺ transition. This is the first conclusive evidence for a charge-state transition involving Cr⁴⁺ in GaAs.

On The Ising Model For Amorphous Ferromagnets, Harry A. Brown

Physics Faculty Research & Creative Works

A calculation is made of the effect on the critical temperature of a ferromagnet whose exchange integrals are taken to be random variables. The Bethe-Peierls-Weiss approximation is used to find the partition function, Z, for an Ising system and then a configuration average is taken to find (InZ), from which the resulting decrease in the critical temperature can be found. Other results are discussed, and comparisons made with the present result.

Nonlinear Anelasticity Of Magnesium, Alexander Aning, Tetsuro Suzuki, Manfred Wuttig

Physics Faculty Research & Creative Works

An approximate solution of the equation of motion of a nonlinear anelastic reed at or near resonance is presented. The steady state solution reproduces the well-known nonlinear resonances. The solution also predicts the existence of auto modulations, i.e., self-excited modulations of the amplitude and phase at constant power of excitation of the reed. Numerical examples of such auto modulations are presented for an antisymmetric deformation potential. Experimental studies of finite amplitude oscillations of a magnesium reed vibrating at 72 and 431 Hz at room temperature confirm the existence of auto modulations. The experimental results can be semi quantitatively described in …

Measurement Of Spin-Exchange Effects In Electronhydrogen Collisions: Further Studies Of Impact Ionization, Timothy J. Gay, G. D. Fletcher, M. J. Alguard, V. W. Hughes, P. F. Wainwright, M. S. Lubell

Timothy J. Gay Publications

Using a Fano-effect polarized electron source and a state-selected thermally dissociated hydrogen beam, we measured the interference between the direct and exchange scattering amplitudes for electron-impact ionization of atomic hydrogen between 14.1 and 30.3 eV. We report the data from these measurements and the results of corrections applied to previously published data.

Electron Capture And Ionisation In H⁺, He2++Li Collisions, Ronald E. Olson

Physics Faculty Research & Creative Works

Single electron capture and ionization cross sections have been calculated for H++Li and He2++Li collisions at energies ranging from 50 to 400 keV amu-1. Double electrons capture cross sections are presented for the He2++Li system. The classical-trajectory Monte Carlo method and the independent-electron model were used to calculate the cross sections. In the energy range investigated, the ionization process is dominated by electron removal of the valence Li(2s) electron, whereas the single and double electron capture processes are the result of capture from the K shell of the lithium atom.

Electron Drift Velocities In Xenon, H. L. Brooks, M. C. Cornell, John L. Fletcher, Ian M. Littlewood, Kaare J. Nygaard

Psychological Science Faculty Research & Creative Works

The electron drift velocity has been measured in xenon over the range of reduced field strength 1 Td

Isotope Effect In Electron-Capture Differential Cross Sections At Intermediate Energies, Eduard P. Rille, Ronald E. Olson, Jerry Peacher, D. M. Blankenship, Thomas J. Kvale, E. Redd, John T. Park

Physics Faculty Research & Creative Works

The isotope dependence in the angular distribution of electron-capture cross sections for protons and deuterons with equal velocity (E=40 keV/u) colliding with atomic hydrogen or deuterium targets is predicted theoretically and observed experimentally. A projectile-dependent effect is observed at small scattering angles. No target dependence was detected in the differential cross sections. A scaling relationship is determined which permits the prediction of differential cross sections for hydrogen-isotope projectiles.

The Mystery Of The Missing Boundary Layer, Gary J. Ferland, S. S. Langer, J. Macdonald, G. H. Pepper, G. Shaviv, J. W. Truran

Physics and Astronomy Faculty Publications

The question of the nature of the ultraviolet and X-ray radiation field of cataclysmic binaries is addressed. The spectrum and luminosity of this radiation are important in determining the mass transfer rate and energy budget of the system and in studies of the ejecta surrounding novae. In many systems, the soft X-ray luminosity is ~ 10²-10⁴ times weaker than predicted by simple accretion models. We discuss several possible solutions to this discrepancy. The most likely are either that the optical luminosity of a typical old nova is produced partly by reprocessed ultraviolet light from the white dwarf, …

Broad Line Region Clouds And The Absorbing Material In Ngc 4151, Gary J. Ferland, R. F. Mushotzky

Physics and Astronomy Faculty Publications

The constraints imposed by X-ray, ultraviolet, and optical observations on the absorbing material in the Seyfert 1.5 galaxy NGC 4151 are discussed. These observations are compared to the predictions of photoionization models of both broad line region clouds, which Holt et al. identify as the source of the extinction, and to models of the narrow line region gas. The weakness of both C III] 1909 and the broad component of Hα relative to C IV 1549, together with the absence of an absorption Balmer jump, indicate that the ionization parameter for the broad line region is a factor …

Iron-Containing Cells In The Honey Bee (Apis Mellifera), Deborah A. Kuterbach, Benjamin Walcott, Richard J. Reeder, Richard B. Frankel

Physics

Honey bees are sensitive to earth strength magnetic fields and are reported to contain magnetite (Fe₃O₄) in their abdomens. We report bands of cells around each abdominal segment that contain numerous electron-opaque, iron-containing granules. The iron is principally in the form of hydrous iron oxides.

Effect Of Anisotropy Strength On Phase Transitions In Random Anisotropy Magnets, Michael J. O'Shea, David J. Sellmyer

David Sellmyer Publications

ac susceptibility and magnetization measurements are reported for a number of Gd and Tb based glasses. Raman magnetic anisotropy effects are observed in both the Gd and Tb glasses. The Gd glasses show a transition to an infinite susceptibility state and in some cases a further transition to an hysteretic state at low temperatures in which field-cooling and magnetic viscosity effects are observed. The Tb glass shows only a small speromagnetic peak at low temperatures. The ratio of anisotropy strength to exchange was varied in the Gd glasses by alloying, and the effect of this on the resulting magnetic states …