Physical Sciences and Mathematics Commons^™

Orientation And Alignment Of The 3P 1P And 4D 1D Levels Of Neutral Helium, R. M. Schectman, R. D. Hight, S. T. Chen, L. J. Curtis, H. G. Berry, Timothy J. Gay, R. Deserio

Timothy J. Gay Publications

The alignment and orientation produced by the tilted-foil excitation of He was studied for a wide range of foil tilt angles and outgoing-atom velocities. In particular, two quantum states of different orbital angular momentum (3p ¹P and 4d ¹D) were investigated and the results were compared with a number of previously proposed models.

Debye–Hückel Theory For Particles Of Arbitrary Electrical Structure, John D. Ramshaw

Physics Faculty Publications and Presentations

Classical linearized Debye–Hückel theory is formulated for a finite fluid system, of arbitrary shape, composed of rigid particles with arbitrary internal electrical structure. The multipole description is eschewed in favor of the more basic description of a particle in terms of its charge density function. This function is left arbitrary, so the particles may be charged or neutral, polar or nonpolar, etc. The theory implies that the direct correlation function c(12)=−v(12)/k T, where v(12) is the Coulomb interaction energy between the charge densities of particles 1 and 2. In the case of uncharged polar …

Photoionization Cross Section For He In The Hyperspherical Coordinate Method, Donald L. Miller, Anthony F. Starace

Anthony F. Starace Publications

The hyperspherical coordinate method developed by Macek, Fano, Lin, and Klar to describe two-electron correlations is used for the first time to treat an atomic photoionization process. Using adiabatic approximations for both the initial and the final state, the cross section for the process He +γ +He⁺1s +e^– is calculated and is found to lie 1% higher than the revised experimental data of Samson at threshold, 4% lower at 1 Ryd above threshold, and 12% lower at 1.9 Ryd above threshold.

Electron-Density Studies Of Metal–Metal Bonds. I. The Deformation Density Of Ti2O3 At 295 K, M. G. Vincent, K. Yvon, A. Gruttner, J. Ashkenazi

Physics Articles and Papers

The electron-density distribution in Ti₂O₃ at room temperature has been determined from single-crystal X-ray diffraction data. The deformation maps show maxima of 0.15 e Å^-3 between the Ti atoms sharing a common face of O-atom octahedra, and maxima of 0.18 e Å^-3 between the O atoms and their four nearest Ti neighbours. These observations support the general view concerning the bonding in Ti₂O₃ and correlate well with the results of theoretical band-structure calculations. In particular, they confirm the existence of a metal-metal bond which is directed parallel to the ternary axis and …

Electron-Density Studies Of Metal-Metal Bonds. Ii. The Deformation Density Of V2O3, M. G. Vincent, K. Yvon, J. Ashkenazi

Physics Articles and Papers

The charge-density distribution in V₂O₃ differs from that in Ti₂O₃ mainly with respect to the deformation of the metal atoms. The V atoms show a positive deformation of up to 0.1 e Å^-3 perpendicular to c in a plane containing three nearest V-atom sites across the edges of the surrounding O-atom octhedra, and a negative deformation of up to 0.3 e Å^-3 parallel to c between the nearest V-atom site across the faces of the O-atom octahedra. These observations are in accordance with theoretical band-structure calculations and confirm the existence of an …

Distorted Wave Born Approximation For Inelastic Collisions: Application To Electron Capture By Positrons From Hydrogen Atoms, Robin Shakeshaft, J. M. Wadehra

Physics and Astronomy Faculty Research Publications

We have re-examined the distorted-wave Born approximation for inelastic collisions. We find that the distortion in the relative motion of the collision partners cannot be neglected even for high-energy ion-atom collisions. Furthermore, if the distortion in the relative motion is not treated exactly, post-prior discrepancies will occur. We have applied the distorted-wave Born approximation, with distortion included through first order, to ground-state-to-ground-state electron capture by positrons from hydrogen atoms. The results are presented in this paper. We have also examined the nonrelativistic asymptotic behavior of the cross section for electron capture from hydrogen by positrons incident with a speed v∼∞. …

Heavy Ion Beam Model For Radiobiology, Rose Ann Roth, Robert Katz

Robert Katz Publications

An ad hoc model of energetic heavy ion beams, including secondary and tertiary particles, has been constructed for predicting radiobiological experiments. While the beam model is relatively primitive, it yields depth-dose and depth-radiobiological calculations in good agreement with experiment upstream of the Bragg peak. Beyond the peak, the model is somewhat coarse grained and seems to underestimate low-LET fragment production. These defects can be repaired at some cost in computer time. Presently a complete set of depth-dose and radiobiological results (RBE, OER, aerobic and hypoxic survival) is obtained in 4–8 min, for a single beam, at a cost of $10. …

Large Momentum Transfer Limit Of Some Matrix Elements, J. M. Wadehra, Larry Spruch

Physics and Astronomy Faculty Research Publications

The matrix element εfi(K), or ε, that appears in the study of elastic and inelastic electron-atom scattering from an initial state i to a final state f in the first Born approximation depends explicitly on the momentum transfer ℏK⃗ . The uncertainty in the value of the calculated cross sections arises not only from the application of the Born approximation but also from the approximate nature of the wave functions used. For the 1 S1−2 P1 transition in helium, we present an analytic expression in terms of the 1 S1 and 2 P1 wave functions for the leading coefficient C1 …

Bulk Magnetic Properties Of Magnetotactic Bacteria, C. R. Denham, R. P. Blakemore, Richard B. Frankel

Physics

Bulk magnetization measurements at room temperature of freeze dried magnetotactic bacterial cells, nonmagnetotactic bacterial cells, and extracted magnetosomes from magnetotactic cells are presented. The role of the magnetosome in the magnetotactic response of swimming cells is discussed.

An Empirical Model Of Quiet Dayionospheric Electric Fields Of Middle And Low Latitudes, A. D. Richmond, M. Blanc, B. A. Emery, R. H. Wand, Bela G. Fejer, R. F. Woodland, S. Ganguly, P. Amyenc, R. A. Behnke, C. Calderon, J. V. Evans

Bela G. Fejer

Seasonally averaged quiet-day F region ionospheric E × B drift observations from the Millstone Hill, St. Santin, Arecibo, and Jicamarca incoherent scatter radars are used to produce a model of the middle and low-latitude electric field for solar minimum conditions. A function similar to an electrostatic potential is fitted to the data to provide model values continuous in latitude, longitude, time of day, and day of the year. This model is intended to serve as a reference standard for applications requiring global knowledge of the mean electric field or requiring information at some location removed from the observing radars. This …

Frequency-Dependent Conductivity In Nbse3, G. Gruner, L. C. Tippie, Jeff Sanny, W. G. Clark, N. P. Ong

Physics Faculty Works

The observation of a frequency-dependent conductivity (σ) and dielectric constant (ε) in NbSe₃ is reported. In both charge-density-wave phases a strong frequency dependence and huge dielectric constant are observed below 100 MHz, with greatest effects observed at 42 K. The conductivity σ increases smoothly from the dc value to the high-frequency (f=100 MHz) limit; this increase is accompanied by the reduction of ε. A resistance-capacitance network model is suggested to account for the observed frequency dependence.

22nd Rocky Mountain Conference On Analytical Chemistry

Rocky Mountain Conference on Magnetic Resonance

Abstracts and meeting program from the 22nd annual meeting of the Rocky Mountain Conference on Analytical Chemistry, co-sponsored by the Rocky Mountain Section of the Society for Applied Spectroscopy and the Rocky Mountain Chromatography Discussion Group. Held in Denver, Colorado, August 10-14, 1980.

Analysis Of Differential Corrosion On High-Silicon Steel Laminations, Sompob Tingthanathikul

Masters Theses & Specialist Projects

The Cutler-Hammer plant in Bowling Green, Kentucky,manufactures laminated steel armatures for electrical starters (large relays) on which corrosion occurs only in some regions. The manufacturing process includes a heat treatment step from which the laminations emerge with a non-uniform surface appearance.

Laminations from corroded regions of an armature have red oxide (Fe₂0^₃) on the edges, while the sides have a black coating of partly-burned cutting-machine oil residue. The purpose of the project was to investigate the mechanisms of this corrosion and why it does not occur uniformly and to suggest practical solutions for the plant.

Emission …

Development Of A System For Water Quality Analysis Using Particle Induced X-Ray Emission, James Albert Andrus

Masters Theses

Particle induced x-ray emission (PIXE) has been in use for several years at Western's accelerator laboratory. Its primary purpose has been to provide trace element analysis of various types of solid samples. The analysis of water samples has not been done because of problems involving target preparation for the accelerator. A process called vapor filtration, developed at Purdue University, allows adequate sample preparation for the accelerator. This process is being adapted for use here at WMU. When completely operational, this system will give the WMU accelerator program the additional capability of performing water quality analyses to concentrations of parts per …

A Study Of The Target Thickness Effect For Chlorine On Germanium From 25 To 49.5 Mev, James Robert Slusser

Masters Theses

No abstract provided.

South-Seeking Magnetotactic Bacteria In The Southern Hemisphere, R. P. Blakemore, Richard B. Frankel, Ad. J. Kalmijn

Physics

Several species of aquatic bacteria which orient in the Earth's magnetic field and swim along magnetic field lines in a preferred direction (magnetotaxis) have been observed in marine and freshwater sediments of the Northern Hemisphere^1,2. Their orientation is due to one or more intracytoplasmic chains of single-domain magnetite particles³. These linearly arranged particles impart a net magnetic dipole moment to the bacterium, parallel to the axis of motility. Northern Hemisphere magnetotactic bacteria with unidirectional motility swim consistently in the direction of the magnetic field, that is, to the geomagnetic North^1,2,4. This implies that their …

Theoretical Potential Curves For Excited States Of Arh And The Rate Of Collisional Quenching Of Metastable Ar By H, R.L. Vance, Gordon A. Gallup

Gordon Gallup Publications

Energy curves for the ground state and the first seven excited states of ArH have been calculated using the multiconfiguration valence bond (MCVB) method. Important features of the excited curves include two distinct avoided crossings between the lowest Ar*H and the highest ArH* potential energy curves. Using these curves we have made a theoretical analysis of quenching of metastable Ar by collision with H at room temperature. Application of the Massey criterion indicates that the separation of the potential curves in the region of the crossing and the acceleration produced by the fall of the reactant channel potential curve from …

Inversion Of The Nonlinear Equations Of Reflection Ellipsometry For Uniaxial Crystals In Symmetrical Orientations, M. Elshazly-Zaghloul, R. M.A. Azzam

Electrical Engineering Faculty Publications

The complex ordinary (N_o) and extraordinary (N_e) refractive indices of an absorbing uniaxial crystal can be determined using reflection ellipsometry. The measurements are taken with the optic axis parallel and perpendicular to the crystal’s surface. The equations obtained are solved without resort to iterative methods; N_o and N_e are determined separately. Sixteen solution sets (N_o, N_e) are obtained and the correct solution can be easily identified. We present an optimum angle of incidence that minimizes the relative errors in N_o and N_e.

Automation Of A Popular Monochromator, David C. Look, J. W. Farmer, R. N. Ely

Physics Faculty Publications

A wavelength‐scan and intensity‐control system for a widely‐used, high‐intensity monochromator is described. The wavelength scan is bidirectional and variable speed, and may be controlled manually or by TTL logic from a computer. The intensity control is effected by use of a programmable dc power supply and D–A converter. Various filters are described which allow an intensity of up to 2×10¹⁴ photons/cm² s to be achieved in a 1 cm×3 cm area over a wavelength range 0.76–2.50 μm, at 0.07 μm bandwidth, with a single grating. (A lesser intensity is available to 3.4 μm.) This wide range is made …

Effect Of Hydrostatic Pressure On The Incommensurate Phase Of K2Seo4, W. Press, C. F. Majkrzak, J. D. Axe, John R. Hardy, N. E. Massa, F. G. Ullman

John R. Hardy Papers

A neutron scattering study of the effect of hydrostatic pressure on the incommensurate phase transformation in K₂SeO₄ was performed in order to obtain information concerning the nature of the competing forces that give rise to a structural instability at a general wave vector. It was found that an increase in pressure lowers the transition temperature (dT_i/dP_i = - 6.5 K/kbar) and results in a smaller value of the initial incommensurate wave vector. The pressure dependence of the incommensurate to ferroelectric phase transition was also investigated (dT_c/dP_c = …

Studies Of H₂O On Ss-Agi Surfaces: An Effective Pair Potential Model, Barbara N. Hale, Jerry Kiefer

Physics Faculty Research & Creative Works

Effective pair potential functions are used to study the adsorption of a water molecule on surfaces of β-AgI. The water molecule is represented by a rigid point charge ST-2 model and the AgI substrate by an array of point atoms with effective charge ±0.6e, Lennard-Jones cores, and ionic polarizabilities. Maximal binding energy surfaces and optimal H₂O configurations are generated for the water molecule adsorbed on the rigid and unrelaxed basal and prism AgI faces. Adsorption of the H₂O above a two layer ledge, an iodine vacancy, and an H₂O trapped in the …

Pressure Dependence Of Fluorescent And Photolytic Interferences In Ho Detection By Laser-Excited Fluorescence, Thomas M. Hard, Robert J. O'Brien, T. B. Cook

Chemistry Faculty Publications and Presentations

In the measurement of HO concentrations by laser-excited fluorescence, expansion of the sampled air offers a way to reduce fluorescent and photolytic interference by other species. The decrease in [HO] upon expansion is balanced by an increase in HO fluorescence yield over a wide range of pressures. Background air fluorescence is reduced if the responsible species have fluorescence yields higher than those of HO. Preliminary experiments indicate that most of the fluorescence observed in laboratory air is due to such species. Upon expansion, the suppression of fluorescent interference can be no greater than the reduction in pressure, whereas the suppression …

Addendum To "Ab Initio Treatment Of Final-State Spin-Orbit Interactions: Photoionization Of The 6s Electron In Cesium", Keh-Ning Huang, Anthony F. Starace

Anthony F. Starace Publications

A previous calculation of the cesium 6s→εp photoionization cross section is extended to include interchannel coupling to the 5p→εd photoionization channels. For photon energies in the range 0.35 a.u.≲ℏω≲1.12 a.u., i.e., just above the near-threshold cross-section minimum, the 6s photoionization cross section is found to be dominated by 5p→5d resonance transitions. No experimental data exist for this energy region.

An Apparatus For Measuring The Thermal Conductivity Of Cast Insulation Materials, Christine A. Wilkins, Robert L. Ash

Mechanical & Aerospace Engineering Faculty Publications

A steady-state apparatus has been developed for measuring the thermal conductivity of cast materials. The design has employed a novel thermal symmetry arrangement which can permit total electrical isolation of the test material from its surroundings. © 1980 American Institute of Physics

Ionospheric Irregularities, Bela G. Fejer, M. C. Kelley

Bela G. Fejer

Extensive experimental and theoretical research has been performed in the last decade to study ionospheric irregularities. These studies have shown that plasma instabilities play a major role in the generation of the irregularities. In this work we describe in detail the recent experimental studies of the E and F region irregularities and also the extensive work on plasma instability theories developed to explain them. We also describe both radio wave and spacecraft-borne experimental techniques to allow a common ground for the understanding of the data from ground-based and in situ experiments. To date, theoretical work has been mostly concentrated on …

Supralinearity Of Peak 5 And Peak 6 In Tld-700, Michael P. R. Waligórski, Robert Katz

Robert Katz Publications

Track theory has been applied to an earlier suggestion, that the supralinearity of TLDs at high gamma-ray doses is due to pre-existing 1-hit and 2-hit trap structures, to calculate high-LET response. Measured 60Co dose responses for peaks 5 and 6 in LiF (TLD- 700) were decomposed to yield parameters characterizing each peak as a two-component c-hit mixture. One value of “trap radius” was assigned to each two-component representation, different for peak 5 and for peak 6, to calculate their responses for H, He, C, O, and Ne bombardments. Calculations reproduce experimental features of the heavy ion response of TLD-700, and …

Influence Of Las Vegas Wash Density Current On Nutrient Availability And Phytoplankton Growth In Lake Mead, John R. Baker, Larry J. Paulson

Publications (WR)

Density currents are commonly formed in reservoirs because of temperature or salinity induced density differences between inflowing and receiving waters. Anderson and Pritchard (1951) were among the first to demonstrate this in their investigations of density currents in Lake Mead. They found that the Colorado River formed an underflow in Lake Mead during the winter, an overflow in the spring and an interflow in the summer and fall. Wunderlich and Elder (1973) have since described the hydromechanics of these types of flow patterns, and density currents have been reported for several other large reservoirs (Carmack et al. 1979, Johnson and …

Nature Of Iron Deposits On The Cardiac Walls In Β-Thalassemia By Mössbauer Spectroscopy, K. S. Kaufman, G. C. Papaefthymiou, Richard B. Frankel, A. Rosenthal

Physics

An identification of the nature and an estimation of the particle size distribution of the iron deposits on thalassemic heart tissue is carried out by variable temperature Mössbauer spectroscopy. Comparison of Mössbauer spectra obtained for the thalassemic heart tissue (I) with those of normal heart tissue (II) and of horse spleen ferritin (III) identifies the iron deposits to be small, superparamagnetic particles of ferritin and/or hemosiderin, two closely related iron storage proteins containing an iron core of (FeOOH)₈(FeO · OPO₃H₂). The dependence of the superparamagnetic relaxation time, τ₂, of magnetically ordered fine …

Effective Force Constant Ratios: Iron In Iridium And Rhodium, Dennis Munsterman

Dissertations and Theses

Classical methods of analyzing heat capacity data for the characteristic moments of the frequency distribution are applied to iridium and rhodium. Impurity moments are determined from high and low temperature f values. These moments are combined by modern theory to estimate the magnitude of the host-host to host-impurity force constant ratio. Ratios of the various host moments are also examined.

Fluid-Structure-Factor Measurements In 4he For 5.5<=T<=7.0 K, Robert Hallock, D. A. Ewen, H. N. Robkoff

Robert Hallock

We report precise measurements of the structure factor S(k) as a function of the momentum transfer k for 4He at T=5.5 and 6.5 K in the density range 10<~ρ<~155 kg/m3. No theoretical predictions that can be tested against the data are available. The recent theoretical work by Bruch et al. at T=7.0 K, ρ=69.6 kg/m3 is in only limited agreement with our experimental data at T=7.0 K, ρ=69.0 kg/m3.