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A Theoretical Study Of The Predissociation Of The O2 B 3Ʃu- Electronic State, Richard Allan Harris

Physics & Astronomy ETDs

It has been known for many decades that the B 3Ʃ_u^- state of the oxygen molecule, the upper state of the Schumann-Runge electronic band system, is predissociated. The predissociation has been attributed to the 3Π_u state, arising from the ground state, separated atom, manifold of molecular states, by previous investigators with the crossing point of the potential energy curves ranging from somewhere on the inner limb to somewhere on the outer limb of the bound excited B 3Ʃ_u^- state. This research has been undertaken to quantitatively describe the observed predissociation. A model with adjustable parameters …

Antithesis In Physical Science, Russell W. Maatman

Pro Rege

No abstract provided.

Kinectics Of The Ground State Transformation In Fe(Ii) (N, N -Dicyclohexylthiourea)6(Cio4)2, R. Latorre, J. A. Costamagna, E. Frank, C. R. Abeledo, Richard B. Frankel

Physics

The high spin complex Fe(II) (N, N'-dicyclohexylthiourea)₆(ClO₄)₆ exists in two forms which only differ in the distortion from octahedral symmetry of the environment of the Fe ion. Thermodynamic data for the transformation from one form to the other as obtained from Mössbauer spectroscopy are presented and a method to derive kinetic parameters is described.

Repeatable Testing-A Tool For Learning Physics, David E. Golden, Robert Fuller, Donald D. Jensen

Robert G. Fuller Publications

Physics courses have traditionally used one-chance-only examinations as a probe to tell the professor how much physics each student has learned, with the result that physics examinations have been a common cause of anxiety among undergraduates.

Repeatable equivalent examinations, on the other hand, offer an alternative testing procedure which underscores material not mastered on the first examination and then allows remedial study of this material for the next examination. Furthermore, the thought that it will be possible to have another try at the examination greatly decreases the anxiety associated with examinations. While repeatable examinations are routinely used in Keller-plan courses, …

Second-Order Raman Scattering In Alkali Fluoride Crystals, S. L. Cunningham, T. P. Sharma, Sitaram Jaswal, M. Hass, John R. Hardy

John R. Hardy Papers

We present theoretical and experimental second-order Raman spectra for NaF, KF, RbF, and CsF. The theoretical calculation follows the formalism of Born and Bradburn. For the lattice-dynamic calculation we use the deformation-dipole model and present comparisons with measured dispersion curves. For the polarizability calculation, we retain all eight first-neighbor and all thirty second-neighbor polarizability coefficients. We find that, in addition to all of the first-neighbor coefficients, only three of the second-neighbor coefficients are needed to obtain good agreement between the calculated and observed spectra both as regards peak positions and over-all shape. Comparison with other types of calculations are made.

Ππ Scattering In The Energy Region 0.6 To 1.42 Gev, J. Díaz, F. A. Dibianca, William J. Fickinger, D. K. Robinson

Faculty Scholarship

ππ scattering amplitudes have been determined in the energy range 0.6 to 1.42 GeV. The amplitudes have been extracted in the framework of an absorption-modified one-pion-exchange model with certain energy-dependent assumptions.

The Effects Of Pentachlorophenol On The Electrical Conductivity Of Lipid Bilayer Membranes, William Harvey Perman

Dissertations and Theses

The effects of pentachlorophenol (PCP), a widely used pesticide, on the electrical characteristics of lipid bilayer membranes has been studied. When a small amount of PCP (even at a concentration of a few micromoles per liter) is present in the electrolytic solution surrounding the membrane, the electrical conductivity of the membrane significantly increases. The present work was concerned with detailed measurements of the changes in the conductivity caused by PCP under chemically controlled conditions. The experimental results were analyzed to determine the permanent species in the membrane, and an attempt was made to correlate the data with existing models of …

16th Annual Rocky Mountain Spectroscopy Conference

Rocky Mountain Conference on Magnetic Resonance

Final program and abstracts from the 16th annual meeting of the Rocky Mountain Spectroscopy Conference, sponsored by the Rocky Mountain Section of the Society for Applied Spectroscopy. Held in Denver, Colorado, August 5-6, 1974.

Measurement Of Neutron Differential Cross Sections Using The Associated Particle Method, Gary Eugene Rochau

Masters Theses

No abstract provided.

On The Reduction Of Many-Body Dielectric Theories To The Onsager Equation, John D. Ramshaw

Physics Faculty Publications and Presentations

An approximate theory for the dielectric constant ℇ of a dense polar fluid was derived by Ramshaw, Schaefer, Waugh, and Deutch (RSWD). In the present article, the RSWD theory is generalized and made rigorous by another method of derivation. The result is a rigorous expression for ℇ which differs from the RSWD expression by the presence of a fluctuation term. Both the rigorous expression and the RSWD expression are then specialized to the Onsager model. It is found that the rigorous expression for ℇ reduces to the Onsager equation, but that the RSWD expression does not because the fluctuation term …

Experiments On Dynamic Parallel Magnetism In Superfluid 3he, Richard A. Webb, R. L. Kleinberg, J. C. Wheatley

Faculty Publications

Observations are reported of the ringing of parallel magnetization in superfluid ³He when an incremental magnetic field parallel to a steady field is suddenly turned off.

Eikonal Distorted-Wave Calculation For The Excitation Of H By He, Jerry Peacher, Richard H. Shields

Physics Faculty Research & Creative Works

The eikonal distorted-wave Born approximation developed recently by Chen, Joachain, and Watson is applied to hydrogen excitation by helium impact in the intermediate-energy range. The differential and total cross sections for the excitation of the hydrogen atom to the 2s, 2p_±, or 2p₀ state by helium impact are presented. These results are compared to experiment and previous calculations. The differential cross section for the excitation of hydrogen to the 2s state compares well with the experimental data of Thomas and Sauers in shape and slope, but has a discrepancy in magnitude.

Heat Transfer Across Carbon - Liquid Helium I Interface, Constantine Antonopoulos

Dissertations and Theses

Carbon samples were electrically heated while immersed in liquid helium I. Their temperature rise was observed on an oscilloscope as a function of the time after the onset of the electric current. There was no indication of the temperature overshoot previously reported for the case of bismuth in liquid helium.

Reasons are presented for the difference in behavior of carbon and bismuth.

Vibration Damping Characteristics Of Typical Harpsichord Strings, Jack Lee Simmons

Dissertations and Theses

Present-day builders of harpsichords disagree as to the use of iron or carbon-steel wire in their attempt to duplicate the tonal qualities of the early 16th century instruments. The variations in tone produced by vibrating iron and steel wires may be due, at least in part, to differences in their decay characteristics. A wire was set into vibration by placing a section in a magnetic field and passing a variable-frequency alternating current through it. A condition of resonance was established by appropriately selecting frequencies, lengths, and tensions that would simultaneously satisfy the relationship: fr = n/2L(T/p)1/2. Then measurements of decay …

A Theoretical Proton-Proton Pair Production Cross-Section Calculation, Jay W. Phippen

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The calculation of both electron-pair and muon-pair production cross-sections was made using Feynman's quantum electrodynamics. Pseudo-scaler coupling was used between the nucleons and vector coupling was used between the photon and the Fermions. The protons were considered as Dirac particles and radiative corrections were omitted.

Eight fourth-order Feynman-Dyson diagrams were used. The subsequent sixty-four TRACES were reduced to seven basic topologically different TRACES. From the seven basic TRACES, it was possible to generate the sixty-four TRACES by the proper permutations of the variables.

With the mathematics and the corresponding computer programs written down, data (energies and momenta which represent the …

Angular Distribution Of Photoelectrons From Atomic Oxygen, Nitrogen, And Carbon, Steven T. Manson, David J. Kennedy, Anthony F. Starace, Dan Dill

Anthony F. Starace Publications

The angular distributions of photoelectrons from atomic oxygen, nitrogen and carbon are calculated. Both Hartree-Fock and Hartree-Slater (Herman-Skillman) wave functions are used for oxygen, and the agreement is excellent; thus only Hartree-Slater functions are used for carbon and nitrogen. The pitch angle distribution of photoelectrons is discussed and it is shown that previous approximations of energy independent isotropic or sin² θ distributions are at odds with our results, which vary with energy. This variation with energy is discussed as is the reliability of these calculations.

Evidence For The Ωππ Decay Modes Of The A₂ And Ω(1675), J. Diaz, F. A. Dibianca, William J. Fickinger, A. Malko, D. K. Robinson, C. R. Sullivan

Faculty Scholarship

We present evidence for the decay A20→ωπ+π0 with a branching ratio Γ(A2→ωππ)/Γ(A2→ρπ)=0.28±0.09 and for the decay ω(1675)→ωπ+π- with a branching ratio Γ(ω(1975)→ωπ+π-)/Γ(ω(1675)→ρπ)=0.47±0.18. Evidence is given for an intermediate B(1235)π state in the ω(1675) decay.

Pb And Bi L-Subshell Ionization Cross-Section Ratios Versus Proton Bombarding Energy From 0.5 To 4 Mev, Don H. Madison, A. B. Baskin, C. E. Busch, Stephen M. Shafroth

Physics Faculty Research & Creative Works

Experimental ratios of L-subshell cross sections are given for ionization of lead and bismuth by 0.5-4-MeV-proton bombardment. The ratio of the L_II to L_I cross sections exhibits a maximum near 1.75 MeV. Individual subshell cross sections are obtained from the experimental ratios and previous total-cross-section data. These subshell ratios and cross sections are compared with the theoretical predictions of the plane-wave Born approximation using nonrelativistic hydrogenic wave functions, of the binary-encounter approximation scaled from Mg K-shell cross sections, and of the binary-encounter approximation scaled from cross sections obtained using L-shell velocity distributions. It was found that both approximations …

Diffusion-Controlled Intrachain Reactions Of Polymers. I Theory, Gerald Wilemski, Marshall Fixman

Physics Faculty Research & Creative Works

A theory of diffusion-controlled intramolecularly catalyzed reactions of polymer chains in dilute solution is formulated. A closure approximation yields a soluble integral equation for (essentially) the transient rate of the reaction. The time dependent solution consists of a sum of simple exponential terms whose coefficients and decay constants can be readily calculated. The theory is also applied to luminescence quenching and ring-chain interconversion.

Diffusion-Controlled Intrachain Reactions Of Polymers. Ii Results For A Pair Of Terminal Reactive Groups, Gerald Wilemski, Marshall Fixman

Physics Faculty Research & Creative Works

The formulas and results of the preceding paper are used to calculate the rate of reaction between reactive groups attached to the ends of a polymer chain. Extensive numerical calculations have been made for both transient rate processes and steady state luminescence quenching. The results are restricted to chains in dilute solution, in either the free draining or nondraining limits and with no excluded volume forces present. A discussion of the qualitative effects of excluded volume forces on the results is included. The results suggest that experimental studies of these processes may be feasible.

Eikonal Approximation Applied To Atom-Atom Excitation At Intermediate Energies: Excitation Of H By H, Richard H. Shields, Jerry Peacher

Physics Faculty Research & Creative Works

The eikonal distorted-wave Born approximation (DWBA) developed recently by Chen, Joachain, and Watson is applied to atom-atom excitation in the intermediate energy range. In this paper the excitation of a hydrogen atom to the 2s, 2p_±, or 2p₀ state by hydrogen impact is considered. Differential cross sections are presented. Total cross sections are presented and compared to previous calculations. It is shown that the eikonal DWBA results for the total cross section approach the two-state distortion-approximation results in the limit of high energy and very-small-angle scattering.

Mössbauer Spectroscopy Of Magnetic Phases In Fecl2 · 2h2O, L. Kandel, M. A. Weber, Richard B. Frankel, C. R. Abeledo

Physics

Mössbauer spectroscopy of the three magnetic phases of single crystal FeCl₂ · 2H₂ in external magnetic fields at 4.2 K is reported.

Incoherent Scatter Radar Observations Of Westward Electric Fields And Plasma Densities In The Auroral Ionosphere, 1, M P. Banks, C L. Rino, Vincent B. Wickwar

All Physics Faculty Publications

This paper reports the results of incoherent scatter radar observations of high-altitude ion drifts and other plasma parameters made February 24, 1972, at Chatanika, Alaska (L = 5.7), during a period of magnetic disturbance. For this experiment, conducted between 0909 to 1303 UT (2309 to 0303 AST), the radar line of sight was held fixed in the magnetic meridian plane so that the observed north-south ion drifts could be interpreted in terms of a westward electric field that ranged in magnitude from −10 to +35 mV m⁻¹. The results confirm many effects found previously through other experimental …

Combined Airglow And Incoherent Scatter Observations As A Technique For Studying Neutral Atmospheric Variations, L L. Cogger, Vincent B. Wickwar, Herbert C. Carlson

All Physics Faculty Publications

Night airglow 6300 Å intensities and electron density altitude profiles observed at Arecibo have been combined with dissociative recombination theory to obtain information about the nighttime variation of F-region N₂ and O₂ densities. The application of this technique is illustrated using data from two nights in March 1971. The gross nighttime variation shows reasonable similarity to the Jacchia [1970] model, and also follows the time variation of the measured exospheric temperature. However, on both nights there is evidence of a postmidnight enhancement of the O₂/N₂ density ratio associated with a rapid decrease in the …

Structural Strain In Small Prenucleation Water Clusters, Donald E. Hagen

Physics Faculty Research & Creative Works

A method is developed for incorporating strain energy into a microphysical treatment of small prenucleation water clusters. The molecules are arranged in a clathrate-cage structure, and this structure is allowed to relax to minimize the strain energy resulting from hydrogen bond stretching and bending. The method is applied to various cluster sizes up to 130 molecules and the results are compared with the classical liquid drop model. The effect of anharmonic terms in the interaction is included.

Fresnel Drag In Uniformly Moving Media, William F. Parks, J. T. Dowell

Physics Faculty Research & Creative Works

A general first-order formula is derived for the Fresnel-drag effect in a uniformly moving medium with a plane surface. The two classical equations due to Lorentz and Laub are shown to be special cases corresponding to different experimental arrangements. The recent experiment of Bilger and Zavodny on Fresnel drag in a ring laser is discussed. © 1974 The American Physical Society.

Measurements Of The Average Electric Dipole Polarizabilities Of The Alkali Dimers, Robert W. Molof, Thomas M. Miller, Henry L. Schwartz, Benjamin Bederson, John T. Park

Physics Faculty Research & Creative Works

The average electric dipole polarizabilities of the homonuclear alkali dimers have been measured in an electric deflection experiment. The molecular results are normalized to the corresponding atomic polarizabilities by comparing deflections of atomic and molecular alkali beams passing through an inhomogenous electrostatic field. The average polarizabilities in units of 10-24 cm3 are: Li2(990°K), 34±3; Na2(736°K), 30±3; K2(569°K), 61±5; Rb2(534°K), 68±7; Cs2(515°K), 91±7. Copyright © 1974 American Institute of Physics.

Statistical Time-Dependent Model For The Interstellar Gas, H. Gerola, Menas Kafatos, R. Mccray

Mathematics, Physics, and Computer Science Faculty Articles and Research

We present models for temperature and ionization structure of low, uniform-density (n ~ 0.3 cm^-3) interstellar gas in a galactic disk which is exposed to soft X-rays from supernova outbursts occurring randomly in space and time. The structure was calculated by computing the time record of temperature and ionization at a given point by Monte Carlo simulation. The calculation yields probability distribution functions for ionized fraction x, temperature T, and their various observable moments. These time-dependent models predict a bimodal temperature distribution of the gas with structure in x, T that agrees with various observations. Cold regions in the low-density …

Phase Transitions In Antiferromagnets In External Magnetic Fields: Mossbauer Spectroscopy, Richard B. Frankel

Physics

No abstract provided.

Charge Transfer Between H ˉIons And O₂ Molecules And D ˉIons And O₂ Molecules In The Ground State., Paul Edgar Chaplin

Masters Theses

"This thesis has been prepared in the style utilized by the Physical Review A. Pages 1-17 will be presented for publication in that journal. Appendices I, II, III, and IV have been added for purposes normal to thesis writing"-- Abstract, p. ii