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Eikonal Approximation For Coupled Equations For Multichannel Scattering, Rung T. Ling, Joseph C.Y. Chen, Jerry Peacher, Kenneth M. Watson

Physics Faculty Research & Creative Works

It is well known that the Glauber approximation for scattering amplitudes is obtained by applying the eikonal approximation to the Fourier transform of the transition operator. The eikonal approximation can also be applied to the coupled equations of scattering obtained by the expansion of the state function in terms of a suitable set of functions. The scattering amplitude can thus be obtained by solving the set of eikonal coupled equations. The latter approach is analyzed for a special class of channel-coupling potentials. The first-order approximation to the derived eikonal coupled equations is the eikonal Born approximation. Numerical illustrations in this …

Hydrostatic Pressure Effects On The Epr Spectrum Of V2+: A1203 And Cr3+: A120, Charles J. Wilcox

Masters Theses

No abstract provided.

14th Annual Rocky Mountain Spectroscopy Conference

Rocky Mountain Conference on Magnetic Resonance

Program and abstracts from the 14th annual meeting of the Rocky Mountain Spectroscopy Conference, sponsored by the Rocky Mountain Section of the Society for Applied Spectroscopy. Held in Denver, Colorado, July 31 - August 1, 1972.

Molecular Model For Prenucleation Water Clusters, P. L. M. Plummer, Barbara N. Hale

Physics Faculty Research & Creative Works

A molecular model applicable to prenucleation water clusters is described. As an illustration the model is applied to water clusters having clathrate-like structures composed of five-menibered rings. This work was motivated by the apparent inadequacies of the corrected liquid drop model which (in addition to applying bulk properties to small clusters) predicts nucleation rates which may be as much as 10¹⁷ larger than experiment. We present the "energy of formation" at a temperature of 277°K for our molecular model for clusters ranging in size from 5 to 57 molecules. These results agree qualitatively with experiment and, we believe, provide …

Nuclear-Magnetic-Resonance Measurement Of The Conduction-Electron G Factor In Cdte, David C. Look, D. L. Moore

Physics Faculty Publications

The effective g factor g^* of conduction electrons in degenerate CdTe has been determined by using measurements of the Cd¹¹³ nuclear spin-lattice relaxation time T₁ and the Knight shift K. It is shown that the magnitude of g^* is given by the Korringa product T₁TK²=C(g^*)², where C is a known constant and T is the absolute temperature, and that the sign of g^* is given by the sign of K for a spherically symmetric conduction band. The measured value, g^*=-1.1±0.1, is within the range allowed …

Schottky Defects In Alkali Halides, Paul D. Schulze, John R. Hardy

John R. Hardy Papers

The method of lattice statics and the deformation-dipole model have been applied to Schottky defects in ionic crystals in approximations higher than zero order. For an isolated vacancy, all host-lattice-ion potential energy functions for short-ranged repulsive and Coulomb-defect forces were expanded to terms quadratic in the displacements and dipole moments, and the resulting forces were allowed to act on the first and/or second neighbors to the vacancy. The zero-order Coulomb force was allowed to act on the remainder of the host-lattice ions past first and/or second neighbors. The vacancy and Schottky-pair-formation energies in the 12 Na, K, Rb halides have …

Nuclear Quadrupole Coupling Of B-12 In A Single Be Crystal, R. L. Williams Jr., Richard C. Haskell, Leon Madansky

All HMC Faculty Publications and Research

Quadrupole resonance lines of β-unstable 12B have been distinctly resolved in a single crystal of Be, and have behaved properly under field reversal and variation of the angle θ between crystal c axis and external magnetic field.

Electronic Properties Of Fe2+ In Cubic Kmgf3 From Mössbauer Spectroscopy, Richard B. Frankel, J. Chappert, J. R. Regnard, A. Misetich, C. R. Abeledo

Physics

Iron-doped KMgF₃ single crystals have been studied by Mössbauer spectroscopy of Fe⁵⁷. Single lines due to Fe²⁺ and Fe³⁺ are observed at room temperature. For TK, the Fe²⁺ line splits into a quadrupole doublet with a splitting ΔE_Q=0.44±0.02 mm/sec. Comparison with a random-strain model due to Ham yields a value of 120 cm^-1 for the position of the first excited spin-orbit split level. Magnetic hyperfine structure in external magnetic fields at low temperature is observed and analysis yields a value of -495 ±30 kOe for the corepolarization hyperfine field …

Studies Of Bistable Fluid Devices For Particle Flow Control, Gerald H. Hogland

Dissertations and Theses

This study was directed toward the development of a bistable wall attachment Flip-Flop device which was capable of directionally controlling particle flow. The particles were transported by a fluid stream which under the influence of wall attachment. The dominant criteria in the development of the device was the achievement of the highest recovery of particles at the active output, without destroying the wall attachment of the fluid stream The experiment was conducted in several distinct stages; each of which was concerned with at least one aspect of wa1l attachment or particle flow. Results derived from one test were used to …

Diffusion-Controlled Reaction Kinetics, David Peak, J W. Corbett

All Physics Faculty Publications

The theory of diffusion-controlled correlated reaction kinetics is developed for the radiation boundary condition (RBC) at the reaction surface. Limited only by the assumptions of purely radial spatial dependence, of a spherical reaction surface, and of continuum diffusion, these results comprise a complete solution for these kinetics. The limiting solutions are obtained for the case of the Smoluchowski boundary condition (SBC) at the reaction surface; numerical solutions are presented, as are the analytic forms of certain limiting cases. The initial recovery for the RBC is linear in time, whereas for the SBC it is well known to be proportional to …

Thomson's E/M Experiment Revisited, Michael Glascock, Don M. Sparlin

Physics Faculty Research & Creative Works

The objective of this experiment is to familiarize the student with the impulse theorem, electron dynamics, and magnetic field contours. He is challenged to obtain accurate as well as precise measurements with suboptimum apparatus through correct analysis. He also investigates the influence of various systematic errors using model calculations on a small computer. © 1972, American Association of Physics Teachers. All rights reserved.

A Correction To Classical Homogeneous Nucleation Theory For Polar Molecules Exhibiting An Electric Double Layer At The Liquid Surface, Daniel R. White, James L. Kassner

Physics Faculty Research & Creative Works

An oriented dipole surface layer is added to the classical liquid drop model of nucleation to account for the surface behavior of substances having polar nonsymmetrical molecules. The preliminary treatment of the change in free energy as given by Abraham is modified to include Fletcher's exponential decay of the degree of orientation. An additional correction for the excess binding energy due to the presence of a foreign molecule in the prenucleation cluster is included to account for the inflections observed in the experimental results of Allen and Kassner. The resulting free energy of formation is combined with the kinetic treatment …

Time-Dependent Ionization Equilibrium And Line Radiation Under Flarelike Conditions, Menas Kafatos, W. H. Tucker

Mathematics, Physics, and Computer Science Faculty Articles and Research

The results of calculations for time-dependent ionization equilibrium and line emission are presented and compared with the values obtained under the assumption that steady-state conditions prevail. In the models considered, it is assumed that the electron density is constant (=10^3 cm^-3) and that the temperature increases by a factor of 10 from 3 x 10^6 K on timescales ranging from 100 to 300 s and decays back to 3 x 10^6 K on a timescale ranging from 600 to 1400 s. Ions of oxygen and silicon are considered, and it is found that the spectrum is softer during the rise …

Detection Of Energetic Heavy Ions, Robert Katz, S. C. Sharma, Mehdi Homayoonfar

Robert Katz Publications

The delta-ray theory of track structure, applied earlier to such 1-or-more hit detection systems as the inactivation of dry enzymes and viruses, the NaI(Tl) scintillation counter, and nuclear emulsion, is extended to the silver activated phosphate glass dosimeter, the LiF thermoluminescent dosimeter, the creation of free radicals in solid biological substances, solid and liquid organic scintillators, and the ferrous sulfate (Fricke) dosimeter. The response of these systems to both gamma-rays and heavy ions is characterized by two parameters: 1) D_γ³⁷, the dose of gamma-rays at which 37% of the sensitive elements remain unaffected by the radiation, and …

The Eikonal Distorted Wave Born Approximation For The Excitation Of Hydrogen By Impact With Hydrogen And Helium In The Intermediate Energy Range, Richard Homer Shields

Doctoral Dissertations

"An eikonal approximation is applied to atom-atom scattering in the intermediate energy range. The theory and the form of the eikonal approximation are reviewed. Also a brief survey of previous theoretical methods for all energy ranges is included.

In particular, the differential and total cross sections for the excitation of hydrogen to the 2s and 2p states by impact on hydrogen and helium atoms have been calculated using the eikonal distorted wave Born approximation (DWBA) for the incident energy range of 2.25-100 keV. The eikonal DWBA differential cross sections are compared to the differential cross sections given by the first …

Radiative And Predissociative Lifetimes Of The A²Σ⁺ State Of Oh, Robert Allen Sutherland

Doctoral Dissertations

"Lifetime measurements have been made on the A²Σ⁺ state of OH by the delayed coincidence technique in conjunction with an interrupted rf discharge through water vapor. Lifetimes are reported for rotational states up to K = 29 and K = 20 in the v = 0 and v = 1 vibrational levels respectively and on the unresolved levels of v =2. A predissociation, previously predicted from relative intensity measurements, resulting from a curve crossing by the repulsive 4 Σˉ state, was observed for the rotational states above K = 23 of v = 0, for those above K = 14 …

Diffusiophoretic Forces Between Juxtaposed Atmospheric Particles, Allen L. Williams

Doctoral Dissertations

"The role of diffusiophoretics and Stefan flow in droplet growth by accretion and in-cloud scavenging is examined. A calculation is made for the diffusive forces between two juxtaposed spheres one or both of which are undergoing diffusional growth and the influence of the diffusive force on the trajectories of two spheres, assumed to obey the creeping flow equations is found. The results are: a) the diffusiophoretic force between two water droplets is zero. b) the diffusiophoretic force between a spherical ice particle and a water droplet, although non-zero, is too small to appreciably influence the fall trajectories. c) the diffusiophoretic …

A Study Of Isospin Mixing In 16O Near 18 Mev Exitation Energy, Li-Yun Kuo

Masters Theses

No abstract provided.

Thermionic Space Charge Oscillations, William Carl

Masters Theses & Specialist Projects

Thermionic electrons emitted into a potential well will produce radiation, the frequency of which is determined by the transit time of the electrons. This paper investigates the case where radiation is produced by a vacuum tube in which two Pierce guns face each other, one acting as the emitter, the other acting as a reflector. Symmetry and the focusing of the electron beam by the Pierce guns make it possible to make an accurate determination of the electron transit time. Measurements showed that the period of the oscillation was 1.5 times the period required for an electron to traverse the …

Mössbauer-Effect Studies Of The Phase Transitions In Antiferroelectric Pbzro₃ And Ferroelectric Pbti₀.₀₂Zr₀.₈O₃, James P. Canner, C. M. Yagnik, Robert Gerson, William Joseph James

Physics Faculty Research & Creative Works

The Mössbauer spectra were studied for the antiferroelectric compound PbZrO₃ and for the closely related ferroelectric PbTi_0.2Zr_0.8O₃. In both cases, a substitution of 5-mol% BiFeO₃ was made to permit the Mössbauer measurements. Little difference was found in the isomer shift in these compounds, whether they were in the ferroelectric, antiferroelectric, or cubic state, indicating that the bonding character is not affected by the transitions among the states. There was a pronounced and approximately equivalent dip in the recoil-free fraction at the Curie points of both the antiferroelectric and ferroelectric materials, associated with …

Cellular Inactivation By Heavy Ions, Neutrons, And Pions, Robert Katz, S. C. Sharma, M. Hamayoonfar

Robert Katz Publications

The delta-ray theory of the inactivation of cells by energetic heavy ions describes cellular survival after heavy ion bombardment through a two-component survival model, in which 4 operational parameters (E₀,m₀, σ₀, and κ) describe the response of a particular cellular variety in a particular ambient condition, for an arbitrary radiation environment. The quantities m and E₀ are the extrapolation number and extrapolated D-37 dose of the survival curve after gamma-ray irradiation. The quantities σ₀ and κ are found from the initial slope of survival curves after irradiation with ions of different LET, …

Nuclear-Magnetic-Resonance Studies Of The Semiconductor-To-Metal Transition In Chlorine-Doped Cadmium Sulfide, Frank D. Adams, David C. Look, Carlton L. Brown, Donald R. Locker

Physics Faculty Publications

Spin-lattice relaxation times (T₁) and Knight shifts were measured for Cd¹¹³ nuclei in 12 CdS crystals doped with various amounts of chlorine. Hall coefficients were measured in order to estimate conduction-electron concentrations. Data were obtained for all samples at 300 °K and for some highly doped samples at 77, 4.2, and 2.13 °K. Metallic properties were observed in all samples having electron concentrations n>2×10¹⁸ cm^-3. At 300 °K, we find 1/T₁∝n for nonmetallic samples and 1/T₁∝n^2/3 when samples are metallic. The latter proportionality continues to hold at lower …

Comment On Electron Scattering In The Image Potential Well, Pavel Smejtek, M. Silver

Physics Faculty Publications and Presentations

Comments are made on the model of electron injection into SiO₂ proposed by Berglund and Powell. Their assumptions on electron scattering, disregarding the change of the escape cone with the distance from the emitter, lead to serious underestimation of the injected current. Two alternative models of electron injection, based solely on elastic scattering are discussed and do not predict the experimental results. We suggest that observed field dependence of the injected current into SiO₂ indicates that energy relaxation associated with the injected electrons is responsible for the voltage dependence of the current.

Evidence For The Existence Of Two Stable Sites For Cobalt Impurity Atoms In Aluminum, Arun Venkatachar

Dissertations and Theses

Using Fe⁵⁷Mössbauer spectroscopy, two alternative sites occupied by cobalt (10^-4 at. % ) impurity atoms in aluminum have been isolated. The substitutional site A is the stable position after annealing the sample above 840 K, followed by a rapid quench. The impurity atoms in site A are characterized by a single line Mössbauer spectrum (indicative of a cubic environment), a room-temperature f = 0.502 (r. m. s. displ. 0.071 A) and an I. S. (reI. to Fe) = -0.421 mm/sec. For anneals below 770 K the cobalt atoms migrate to site B, which is characterized by a …

Application Of The Method Of Lattice Statics To Vacancies In Aluminum, Larry Boyer, John R. Hardy

John R. Hardy Papers

In this paper the method of lattice statics is applied to the calculation of the atomic displacements about a vacancy in aluminum using a fifth-neighbor force-constant model for the dynamical matrix and the vacancy-host lattice interaction. The strain-field interaction energy between two vacancies is similarly calculated. The main object of this work is to demonstrate the important modifications of earlier results, obtained for a first- and second-neighbor force-constant model, when one uses the fifth-neighbor model designed to give a significantly better fit to the measured phonon dispersion curves. In particular it is demonstrated that the displacements about the vacancy continue …

13th Annual Rocky Mountain Spectroscopy Conference

Rocky Mountain Conference on Magnetic Resonance

Program and abstracts from the 13th annual meeting of the Rocky Mountain Spectroscopy Conference, hosted by the Rocky Mountain Section of the Society for Applied Spectroscopy. Held in Denver, Colorado, August 9-10, 1971.

Energy Calibration Of The Western Michigan University Model En Tandem Accelerator, Michael Joseph Parrott

Masters Theses

No abstract provided.

On The Molecular Theory Of Dielectric Polarization In Rigid‐Dipole Fluids, John D. Ramshaw

Physics Faculty Publications and Presentations

A molecular theory is developed for the polarization P(r) produced by a weak position‐dependent external electric field E₀(r) in a finite fluid system, of arbitrary shape, composed of rigid polar molecules. The theory differs from earlier work in that no assumption is made concerning the form of the electrostatic constitutive relation. [The usual assumption in this regard is that P(r) = (ε–1) E(r) / 4π, where E(r) is the total Maxwell electric field. The “dielectric constant” ε is well defined only if the relation between P(r) and E(r) …

An Application Of Spectroscopic Techniques To The Measurement Of Electron Density And Temperature In A Brush Cathode Plasma, Ramabhai M. Patel

Physics Theses & Dissertations

A brief review of the Langmuir probe, microwave and spectroscopic techniques most commonly used to make measurements .of plasma electron temperature and density is presented. Of these various methods, certain spectroscopic methods are applied to the measurements of electron density and temperature in a helium brush cathode plasma. The density measurement is based on the manner in which a series of Stark broadened spectral lines merges into an apparent continuum before the normal series limit is reached. This approach met with only limited success in that the density could be determined only by extrapolating the data obtained. Primarily because of …

Laser Induced Optical Modulation In Zinc Selenide, Donald Edward Everett

Master's Theses

The experiments reported here with zinc selenide have a two-fold purpose. First, by using basically the same experimental set-up as Conway did, we are attempting to duplicate this LIMA using zinc selenide instead of cadium sulfide. Unlike his set-up, primarily one laser chopping frequency was used. Also, only one laser wavelength, 632.8 nanometers, was available, where Conway used lasers of wave­ lengths 647.1 nanometers and 530.8 nanometers. Another main difference is that in earlier works by Conway, laser pulse duration was of the order of 40 milliseconds, whereas the present duration is approximately 2.5 milliseconds. It was observed that the …