Digital Commons Network^™

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 …

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.

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.

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.

Basic Physics Of Emp, Beam Weapons, And Abm, David W. Hafemeister

Physics

No abstract provided.

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 …

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 …

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.

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

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 …

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.

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.

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.

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 …

Elastic Differential Cross Sections For Small-Angle Scattering Of 25-, 50-, And 100-Kev Protons By Helium Atoms, Jerry Peacher, Thomas J. Kvale, E. Redd, Paul J. Martin, D. M. Blankenship, Eduard P. Rille, V. C. Sutcliffe, John T. Park

Physics Faculty Research & Creative Works

The first measurements of elastic differential cross sections have been carried out for 25-, 50-, and 100-keV protons scattered through very small angles by helium atoms. The University of Missouri Rolla energy-loss spectrometer provided the required high angular resolution and also separated the elastically scattered ions from the inelastically scattered ions. The data are compared to our Born, Glauber, and classical calculations as well as a four-state calculation. All of the measured elastic differential cross sections are more sharply peaked than theory for the smallest scattering angles. At the larger scattering angles all of the measured elastic differential cross sections …

Structural Effects On K-Vacancy Production By Protons Of Extreme Relativistic Energies, P.T. Leung, M. L. Rustgi

Physics Faculty Publications and Presentations

The effect on the K-vacancy-production cross section due to the finite distribution of charge and magnetic moment of the incident proton is examined. Numerical results are given for two target elements, namely, Ni and U. The results show that even at energy as high as 10³ GeV the incident proton can still be regarded as a point charge. The effect on the stopping power of matter is discussed.

Subharmonic Generation By Resonant Three‐Wave Interaction Of Deep‐Water Capillary Waves, Partha P. Banerjee, Adrianus Korpel

Electrical and Computer Engineering Faculty Publications

Subharmonic generation has been observed during the propagation of deep‐water capillary waves. The observations are shown to be in agreement with the theory of degenerate resonant noncollinear three‐wave interaction in a nonlinear, dispersive medium.

Magnetic And Crystallization Studies Of Splat-Cooled Praseodymium–Gallium–Iron Alloys, George C. Hadjipanayis, S.H. Woollins, R.C. Hazelton, K.R. Lawless, R. Prestipino, David J. Sellmyer

David Sellmyer Publications

Magnetic hysteresis and crytallization studies are reported for several (Pr₈₀Ga₂₀)_100-xFe_x metallic glasses, where 30≤x≤80. Thermomagnetic data show the presence of two magnetic phases which are probably responsible for the relatively high coercive fields observed at cryogenic temperatures. As the iron content of the sample is increased, the magnetic moment increases substantially but the coercivity is drastically reduced. In (Pr₈₀Ga₂₀)₇₀Fe₃₀ the observed coercive fields are strongly temperature dependent indicating strong thermal activation effects which are consistent with the magnetic viscosity measurements. The hard magnetic properties disappear after …

Magnetic Properties Of Hydrides Of Rare Earth–Transition Metal Glasses, C.G. Robbins, Z.D. Chen, J.G. Zhao, Michael J. O'Shea, David J. Sellmyer

David Sellmyer Publications

The effect of hydrogen on magnetic properties of metallic glasses of the form (R₈₀Ga₂₀)_1-xT_xH_y where R=Pr, Nd, Gd, Tb, Er; T=Cr, Fe, Co, B; 0≤x≤0.3 and 0≤y≤1.7 is reported. The anisotropic rare earth glasses without H all exhibit speromagnetic (spin-glass-like) transitions and the effect of hydrogen, in most cases, is to lower the peak in χ_ac significantly but leave T_C relatively unchanged. For the Gd glass with T=Fe and x=0.1 the introduction of H at the level y=0.55 causes a large decrease in T_C and a significant increase …

Electron Transport In Tb- And Pr-Based Metallic Glasses, S.G. Cornelison, David J. Sellmyer

David Sellmyer Publications

Electrical resistivity measurements are reported on several metallic glasses based on Pr and Tb, and Ga and various transition metals as the glass formers. In general negative temperature coefficients were observed and these are discussed in terms of the extended Ziman theory and the tunneling or localization theory. Low temperature structure in the resistivity can be understood with the coherent exchange scattering model of Asomoza et al. Journal of Applied Physics is copyrighted by The American Institute of Physics.

Resistivity And Galvanomagnetic Coefficients Of Iron Group Metallic Glasses With Chromium Substitutions, J.R. Long, George C. Hadjipanayis, David J. Sellmyer

David Sellmyer Publications

Magnetic field and temperature dependences of the electrical resistivities and Hall resistivities were measured for the metallic glass ferromagnets Fe₁₃Ni₆₀Cr₅Si₁₀B₁₂, Fe₃₇Ni₃₆Cr₅Si₁₀B₁₂, Fe₈₁B_13.5Si_3.5C₂, and Fe₅Co₇₅Si₁₅B₅. Resistance minima and magnetoresistivity of the FeNiCr glasses have been found to be consistent with a modified Kondo model of low temperature scattering. The Hall resistivities are positive and large. The spontaneous Hall coefficients of the FeNiCr glasses are in …

Amorphous FeXNb100-X With Wide Composition Range, C.L. Chien, K.M. Unruh, Sy_Hwang Liou

Sy-Hwang Liou Publications

Sputtered amorphous Fe_xNb_100-x (30 ≤ x ≤ 85) has been studied by Mössbauer spectroscopy and resistivity measurements. The samples with x< 60 are nonmagnetic. The magnetic ordering temperatures of the samples with x ≥ 60 increase with Fe content. Small magnetic hyperfine fields are observed in the magnetic samples, consistent with the small Fe moments measured. The resistivity of the magnetic and nonmagnetic samples show different temperature dependences. Only the magnetic samples exhibit a resistivity minimum, indicating a Kondo-like mechanism.