Digital Commons Network^™

Field Radiation Of Spin I Massless Particle, Ralph Alvin Mudgett

Masters Theses

No abstract provided.

A Photographic Study Of The Infrared Oh Airglow, G. C. Loos

Physics & Astronomy ETDs

OH airglow is due to the rotational-vibrational transitions of the hydroxyl radical. Previous efforts to find the airglow's emission height in the atmosphere are discussed. Photography of the infrared airglow with a fast 35mm camera and Eastman Kodak high speed infrared film is described and a method for triangulating emission heights by two station photography is explained. The techniques for reduction of film data to height measurements and velocity measurements are presented. Observations are reported concerning the frequency of occurrence of bright spots and other features on the OH background and the intensity of the airglow as a function of …

Self‐Focusing Of Laser Light In The Isotropic Phase Of A Nematic Liquid Crystal, D.V.G.L.N. Rao, S. Jayaraman

Physics Faculty Publications

Self‐focusing of ruby laser light is studied as a function of sample length and temperature in the isotropic phase of nematic liquid‐crystal MBBA. The critical power for self‐focusing, 0.36 kW, observed near the phase transition temperature is a factor of 20 times less than that for CS₂. The corresponding nonlinear index 4.4 × 10⁻¹⁰ esu is the largest value known so far for any material.

Dissociative Attachment From The O2 (A1 Δ G) State, P.D. Burrow

Paul Burrow Publications

The dissociative attachment cross section for production of O^- by electron impact on the metastable O₂ (a¹ Δ _g) state is studied. The cross section is found to be 4.6 ± 1.3 × 10^-18 cm² at its maximum. From the measured energy dependence, we infer that the dissociative attachment process takes place through the O^2̅ (² П_u) state as in the case of O^- production from the O₂ ground state. The information thus obtained is used to estimate the portion of the cross section for excitation of the …

Raman Spectrum Of Gadolinium Molybdate Above And Below The Ferroelectric Transition, Frank Ullman, B. J. Holden, B. N. Ganguly, John R. Hardy

John R. Hardy Papers

90 °-scattered Raman spectra of single-domain gadolinium molybdate have been obtained at room temperature and above the 159 °C ferroelectric transition on several crystal orientations. Lines in the 0-200-cm^-1 range can all be associated with Raman-active phonons and are identified by symmetry considerations, scattering-efficiency calculations, and comparison of spectra for different crystal orientations. Lines in the 200-1000-cm^-1 range can be identified with coupled vibrations of tetrahedral molybdate ions. Spectra for frequencies above 1,000 cm^-1 originate from impurity flourescence. The effect of the presence of multiple domains on the spectra was determined; the observed differences between single-domain and …

Orbital Ground State Inversion In [Fe(H2O)6](Clo4)2, W. M. Reiff, Richard B. Frankel, C. R. Abeledo

Physics

Mössbauer spectroscopy in external magnetic fields has been used to measure the signs of the principal components of the electric field gradient V_zz in the two forms of [Fe(H₂O)₆)(Cl0₄)₂. The signs are V_zznegative for low temperature form (A) with quadrupole splitting ΔE_A = 3.4 mm/sec, and V_zz positive for high temperature form (B) with ΔE_B = 1.4 mm/sec. This implies a trigonally distorted ligand field and the transition (A) → (B) corresponds to compression → elongation with respect to the trigonal axis.

Hyperfine Interactions In The Intramolecular Antiferromagnet (Fe Salen C1)2, R. Lechan, C. Nicolini, C. R. Abeledo, Richard B. Frankel

Physics

Magnetic hyperfine interactions in (Fe salen C1)₂ have been studied using the Mössbauer effect in external magnetic fields up to 80 kOe and for 4.2 ≤ T ≤ 80 °K. The low‐temperature results are adequately described by a simple intramolecular exchange model with J = 7.0 cm⁻¹ and a hyperfine interaction constant of −180 kOe per unit spin. At higher temperature the effective field approximation breaks down. Data for (Fe salen)₂O are also briefly reported.

Magnetic Interactions And High-Field Magnetization In Dilute Magnetic Alloys , J.M. Franz, David J. Sellmyer

David Sellmyer Publications

Magnetic interactions have been investigated in Cu(Mn) and Cu(Fe) alloys with concentrations ranging from several hundred to several thousand ppm. In each system two sets of alloys were prepared in different ways to test for sensitivity to structrual modifications. In the Cu(Mn) alloys there was very little difference in magnetic properties of the two sets of alloys which is consistent with the expectation that the Cu(Mn) alloys form good random solid solutions. The magnetic properties were compared with the recent mean-random-field theory of Klein in the low-temperature limit. It was found that the theory is able to explain the concentration …

Lattice Dynamics Of A Rigid-Ion Model For Gadolinium Molybdate, L. L. Boyer, John R. Hardy

John R. Hardy Papers

Results of lattice-dynamical calculations are presented which support the view that the ferroelectric phase transition in gadolinium molybdate (GMO) arises from the softening and ultimate instability of a doubly degenerate zone-edge mode of the high-temperature paraelectric phase. We have used a rigid-ion model in which the short-range force constants are obtained from a detailed knowledge of the crystal structure together with the conditions imposed by the requirement that the crystal must be in static equilibrium under the combined influence of both Coulomb and short-range forces. Our results show that this type of approach is very useful when one is dealing …

Orbital Ground State Reversal In The High‐Spin Complex Fe(Ii) (N, N′‐Dicyclohexylthiourea)6(Clo4)2, R. Latorre, C. R. Abeledo, Richard B. Frankel, J. A. Costamagna, W. M. Reiff, E. Frank

Physics

Mössbauer spectroscopy of iron (II)(N, N′‐Dicyclohexylthiourea)₆ (ClO₄)₂ shows the existence of two isomers. At low temperatures (T < 200°K) a form A with quadrupole splitting ΔE = 3.31 mm∕sec is stable. At and above room temperature a form B with ΔE = 1.32 mm∕sec is stable. For 200 °K < T < 300°K both forms are observed with the B∕A ratio increasing with increasing temperature. The values of ΔE are typical of Fe²⁺ with an orbital singlet and an orbital doublet ground state for A and B, respectively. The isomer shift and magnetic susceptibility results indicate that both …

High Magnetic Field Behavior Of Iron Impurities In Chromium, Richard B. Frankel, N. A. Blum

Physics

Mössbauer measurements in ⁵⁷Fe in dilute FeCr alloys in external magnetic fields up to 140 kOe are presented. The magnetic hyperfine interactions are compared with results obtained by Herbert, Clark and Wilson and are discussed in terms of a model due to Housley and Dash.

15th Annual Rocky Mountain Spectroscopy Conference

Rocky Mountain Conference on Magnetic Resonance

Program and abstracts from the 15th 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 20-21, 1973.

Synthetic Analogs Of The Active Sites Of Iron-Sulfur Proteins. Structure And Properties Of Bis[O-Xylyldithiolato-Μ2-Sulfidoferrate(Iii)], An Analog Of The 2fe-2s Proteins, J. J. Mayerle, Richard B. Frankel, R. H. Holm, James A. Ibers, W. D. Phillips, J. F. Weiher

Physics

The synthetic analog approach has been applied to a clarification of the active sites of 2Fe-2S* proteins. The compound (Et₄N)₂[FeS(SCH₂)₂C₆H₄]₂, derived from o-xylyl-α,α′-dithiol, has been prepared and its structure has been determined by x-ray diffraction. The centrosymmetric anion contains two tetrahedrally coordinated ferric ions bridged by two sulfide ions and separated by 2.70 Å. Comparison of electronic, Mössbauer, and proton magnetic resonance spectra and magnetic susceptibility of the anion with the corresponding properties of the oxidized forms of the proteins reveals …

Observation Of The Decay Ƒ⁰→Π⁺ Π⁺Π‾ Π‾, J. Diaz, F. A. Dibianca, William J. Fickinger, D. K. Robinson, C. R. Sullivan

Faculty Scholarship

We have observed the decay mode f0→π+π+π-π- and determined the branching ratio Γ(f0→π+π+π-π-)/Γ(f0→π+π-)=(5.5±1.0)×10-2.

Determination Of (N, 2n) Reaction Isomeric Cross Section For 87rb, 112cd, 138bz, And 186w Using 14 Mev Neutrons, Hsiao-Chueh Kao

Masters Theses & Specialist Projects

The purpose of this investigation was to measure the cross section for each of the reactions 87_{Rb(n, 2n)} 86m_Rb, 112_{Cd(n, 2n)}111m_Cd, 138_{Ba(n, 2n)} 137m_Ba and 186_{W(n, 2n)} 185m_W at 14.7 ± 0.03 MeV incident neutron energy. The incident neutron flux was determined during each irradiation from the activity produced in copper or aluminum disks between which the isotopically enriched sample was sandwiched. The 63_{Cu(n, 2n)}62_Cu and 27_{Al(n, p)}27_Mg reaction cross sections were assumed to be 593 ± 45 mb and 73 ± 5 …

Comment On "Length And Velocity Formulas In Approximate Oscillator-Strength Calculations", Anthony F. Starace

Anthony F. Starace Publications

A previous paper by Starace showed that the length formula for the electric-dipole matrix element is the only consistent one for calculations that solve for the exact eigenfunctions of an approximate Hamiltonian containing a nonlocal potential. It is emphasized here that disagreement between such a length-formula calculation and experiment indicates inadequacy of the approximate Hamiltonian and not that the velocity formula may be preferable.

Angular Distributions Of Protons From The 28Si(∝,P)31P Reaction, Susan Mary Allen

Masters Theses

No abstract provided.

Hot Electron Injection Into Dense Argon, Nitrogen, And Hydrogen, Pavel Smejtek, M. Silver, K. S. Dy, David G. Onn

Physics Faculty Publications and Presentations

Hot electrons have been injected into very dense argon, nitrogen, and hydrogen gases and liquids. The current‐voltage characteristics are experimentally determined for densities (N) of argon, nitrogen, and hydrogen ranging from about 10²⁰ to 10²² cm⁻³ and applied fields (E) ranging from about 10 to 10⁴ V cm⁻¹. The argon data show a square root E∕N dependence of the current. The nitrogen and hydrogen data show a complicated dependence of the current on E∕N due to the rapid thermalization in the region of the image potential of the injected electrons through inelastic collision processes not present in argon. A hydrodynamic‐two‐fluid …

Properties Of 1‾ Excited States Of Complex Nuclei, Carlos Ignacio Calle

Masters Theses

No abstract provided.

Intensity Correlation Spectroscopy Of Heme Proteins And Motile Microorganisms, Gordon E. Banks

Physics & Astronomy ETDs

The recently developed technique of autocorrelation of intensity fluctuations of Rayleigh (quasi-elastically) scattered light allows measurement of some dynamic properties of particles in solution. The origin of the intensity fluctuations and the form of the correlation spectra for various situations are discussed. The apparatus and methods are described along with methods of data reduction and sources of error. Measurements were made using a Spectra-Physics Model 125 (50mW) He-Ne laser (6328Å) in conjunction with a Saicor 43A 400 channel correlation and probability analyzer. The diffusion coefficient of cyanometmyoglobin was found to be D_{20, w} = (9.47 ± 0.28) x 10 …

Study Of The Reaction Π⁺N→Ωp At 6.0 Gev/C, J. Diaz, F. Dibianca, William J. Fickinger, D. K. Robinson

Faculty Scholarship

An analysis of the reaction π+n -> wp in a 6.0 GeV/c bubble chamber experiment is presented. The production differential cross section and spin density matrix elements are compared with Regge exchange models.

Magnetoresistance In Iron And Cobalt To 150 Koe , R.V. Coleman, R.C. Morris, David J. Sellmyer

David Sellmyer Publications

Magnetoresistance anisotropy and field dependence have been studied in single crystals of iron and cobalt in fields up to 150 kOe in the temperature range 1-4.2 K. The crystals of iron and cobalt had residual resistance ratios up to ∼4600 and ∼400, respectively. The relation Δρ/ρ₀=aBⁿ has been studied for both metals and in the case of iron the exponent n approaches values in the range 1.8-1.9 for fields up to 90 kOe and then decreases to the range 1.3-1.5 at 150 kOe. This decrease in the exponent has been observed for all field and current …

Electron-Beam Retardation Contact Potential Of Cuprous Oxide, James Lindle

Masters Theses & Specialist Projects

The purpose of this research is to determine the contact potential of cuprous oxide, Cu₂O, with respect to gold. A band model for cuprous oxide is presented.

Single-crystal cuprous oxide is prepared from Oxygen Free High Conductivity copper equilibrated at 120°C and at atmospheric pressure. The contact potential difference of cuprous oxide (using gold as a reference) is measured in a bakeable ultrahigh vacuum system using a modified version of Nelson's electron beam retardation method. Measurements made at 10^-6 torr and at room temperature give a value of 0.1 +/-0.05 eV for the contact potential difference of …

Proton-Scattering On (29)Si In Range Ep = 2.5-3.4 Mev*, Joseph W. Hemsky, S. C. Ling, Paul J. Wolfe

Physics Faculty Publications

Elastic and inelastic proton scattering measurements on Elastic and inelastic proton scattering measurements on ²⁹Si have been obtained in the energy range E_p = 2.5-3.4 MeV. 30 elastic and 32 inelastic resonances were observed. 14 prominent resonances from elastic scattering were analyzed. Results of the analysis for proton orbital momenta, spin and parity assignments, and proton partial widths are given. The inelastic resonance strengths measured relative to the known strength of the 1302-keV resonance in ²⁹Si(p,y)³⁰P are also reported.

Sensor Package For Electrical Sensing Of Plane Coordinates And Method Of Preparing The Same, George S. Hurst, William C. Colwell Jr.

Physics and Astronomy Faculty Patents

A sensor package for ready insertion in properly registered position upon, or for removal from, a cabinet employed in electrical sensing of plane coordinates, is constructed to provide accurate readings when pierced by a small manually operated cursor.

A method for manufacturing the package including the affixing of accurately spaced electrodes on the package, is disclosed.

A Relativistic One Pion Exchange Model Of Proton-Neutron Electron-Positron Pair Production, William A. Peterson

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Proton-neutron electron-positron pair production cross sections are calculated in the framework of the pseudoscalar one-pion exchange model in a fully relativistic manner.

A computer program has been developed to evaluate invariants and Dirac traces for a given data point.

The sections for symmetric coplanar events for laboratory kinetic energies of 10 to 250 MeV were calculated for pair angles of 20° to 120°.

Frequency distributions were also calculated, at a laboratory energy of 200 MeV, using a random number generator to select data points. The frequency distributions are illustrated by curves.

It was noted that the inclusion of heavier bosons …

Dynamic Impulse Calibration Of Sheet Loaded Explosive, William James Johnson

Physics & Astronomy ETDs

In the past, experimenters have used Sheet Loaded Explosive (SLE) to simulate the damage caused by x-rays to an ICBM as the result of a nuclear burst from an ABM. One of the attractive features of SLE is that it can also provide high impul3e levels for structural damage studies. Previous measurements of the usual shock parameters such as peak overpressure, ietonation velocity, and shock front definition with short time interval pressure transducers were not suitable for total impulse measurements. The High Explosive Impulse Responder (HEIR) was developed to fill the need for a simple, reliable and economical total impulse …

Quasi-Landau Spectrum Of A Hydrogen Like Atom In A High Magnetic Field, Anthony F. Starace

Anthony F. Starace Publications

A two dimensional semiclassical approximation is used to examine the σ polarization spectrum of a hydrogen like atom in a strong magnetic field. Resonances above the zero field ionization limit are found and their energy separations are computed over the region from the ionization limit to 40 ħω_c above, where ω_c is the cyclotron frequency, for magnetic fields of 10, 17, 25, 32, 40 and 47 kG. At the ionization limit the separation between resonances is found to be 1.500 ħω_c, independent of magnetic field strength, which is in agreement with a separation of 1.5 ħω …

Evaluation Of An Experiment In Computer -Assisted Tutoring, Stephen L. Cunningham, Robert Fuller

Robert G. Fuller Publications

It was made apparent from the presentations at the Conference of Computers in Undergraduate Science Education that very few Computer-Assisted Instructional (CAI) programs in physics attempt to evaluate the performance of computer- tutored students in comparison with a control group. In this note, we discuss an experiment in which 23 beginning physics students out of a class of 64 were given a computer-administered tutoring test in place of the regular review recitation session prior to an hour exam on relativity. The performance of the computer-tutored group on the exam was compared to the performance of the rest of the class.

Li-8 Magnetic Dipole-Moment, Richard C. Haskell, Leon Madansky

All HMC Faculty Publications and Research

Polarized 8Li nuclei recoiling from the reaction 7Li(d, p)8Li were implanted in Au, Pd, and Pt foils, and the Knight-shifted values of the 8Li magnetic dipole moment in these metals were measured by a resonant depolarization technique. From measurements of the spinlattice relaxation times of 8Li implanted in Au, Pd, and Pt, the Knight shifts of 8Li in these metals were estimated. A corrected value for the magnetic dipole moment of 8Li was found to be μ(8Li)=(1.653 35±0.000 35)μN. Attempts were also made to measure the quadrupole couplings of 8Li in single crystals of Be and Mg. While the resonance …