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Electron Irradiation Defects In N-Type Gaas, J. W. Farmer, David C. Look Apr 1980

Electron Irradiation Defects In N-Type Gaas, J. W. Farmer, David C. Look

Physics Faculty Publications

We have studied the production and annealing of defects produced by 1-MeV electron irradiation of n-type GaAs. Two of these defects lie at 0.15 and 0.31 eV from the conduction band, respectively; in addition, there is at least one acceptor much closer to the valence band. The carrier-removal rate depends upon sample purity but is independent of the irradiation flux. The removal rate is also highly dependent upon the position of the the Fermi level, an effect which is considered in some detail. At about 200°C, the defects recover in two stages, with the respective recovery rates given by λ …

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Studies Of The Reorientational Relaxation Of Pyridine In Water By Depolarized Rayleigh Light Scattering, C. H. Wang, Scott L. Whittenburg, P. A. Lund, D. H. Christensen Apr 1980

Studies Of The Reorientational Relaxation Of Pyridine In Water By Depolarized Rayleigh Light Scattering, C. H. Wang, Scott L. Whittenburg, P. A. Lund, D. H. Christensen

Chemistry and Biochemistry Faculty Publications

The depolarized Rayleigh spectra of aqueous solutions of pyridine have been studied using a high‐finesse Fabry–Perot interferometer as a function of temperature and concentration. The Rayleigh relaxation times are found to have a complex concentration and viscosity dependence. The classical Stokes–Einstein–Debye equation for molecular reorientation breaks down in this system. The Rayleigh relaxation time of pyridine molecules is not determined by the macroscopic shear viscosity of the solution. The specific interaction due to the formation of hydrogen bonds between pyridine and water molecules plays a very important role in affecting the relaxation time. At a fixed temperature the plot of …

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Partial Chemical Equilibrium In Fluid Dynamics, John D. Ramshaw Apr 1980

Partial Chemical Equilibrium In Fluid Dynamics, John D. Ramshaw

Physics Faculty Publications and Presentations

An analysis is given for the flow of a multicomponent fluid in which an arbitrary number of chemical reactions may occur, some of which are in equilibrium while the others proceed kinetically. The primitive equations describing this situation are inconvenient to use because the progress rates ω [subscript s] for the equilibrium reactions are determined implicitly by the associated equilibrium constraint conditions. Two alternative equivalent equation systems that are more pleasant to deal with are derived. In the first system, the ω [subscript s] are eliminated by replacing the transport equations for the chemical species involved in the equilibrium reactions …

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Potential Use Of Chemical Spot Test Method For Submicron Aerosol Sizing, Paul C. Yue, Josef Podzimek Mar 1980

Potential Use Of Chemical Spot Test Method For Submicron Aerosol Sizing, Paul C. Yue, Josef Podzimek

Physics Faculty Research & Creative Works

A submicron particle, which is too small to be observed in an optical microscope, may form an observable spot on a chemically prepared substrate of the collector. The size of the spot or "Liesegang circle" is related to the aerodynamic diameter of the particle through a magnification factor. This paper presents the experimental results of the study of this factor using sodium chloride aerosol in the size range of 0.5 to 2 pm which has not previously been studied. We calibrated a cylindrical centrifuge with known sized latex particles. A relationship between the aerodynamic diameter and the deposition length is …

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Angular Differential Cross Sections For Excitation Of Atomic Hydrogen To The N=2 Level By Proton Impact, John T. Park, John E. Aldag, Jerry Peacher, Jacob M. George Mar 1980

Angular Differential Cross Sections For Excitation Of Atomic Hydrogen To The N=2 Level By Proton Impact, John T. Park, John E. Aldag, Jerry Peacher, Jacob M. George

Physics Faculty Research & Creative Works

Differential cross sections for 15-145-keV proton impact excitation of atomic hydrogen to the n=2 level have been determined for center-of-mass scattering angles 0 to 1.2 mrad. The cross sections were obtained from an analysis of the angular distribution of protons which had lost an energy corresponding to the excitation of atomic hydrogen to its n=2 level. The differential cross sections obtained are in rather good agreement with available coupled-state calculations as well as the simpler Glauber-approximation calculations. However, at the larger scattering angles the cross sections obtained from the theoretical treatments appear to decrease more rapidly than the experimental data.

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Photoionization Of The 5S Subshell Of Xenon: A Multichannel K-Matrix Calculation Including Spin-Orbit Interactions, Keh-Ning Huang, Anthony F. Starace Mar 1980

Photoionization Of The 5S Subshell Of Xenon: A Multichannel K-Matrix Calculation Including Spin-Orbit Interactions, Keh-Ning Huang, Anthony F. Starace

Anthony F. Starace Publications

Ab initio theoretical calculations are presented for the cross section, angular distribution, and spin polarization of photoelectrons for the 5s subshell of xenon. Starting from an initial basis of nonrelativistic Hartree-Fock wave functions, the authors treat the effect of final-state spin-orbit interaction in the Breit-Pauli approximation exactly. Electrostatic correlations between the 5s and 5p subshells are also included. Good agreement is obtained with experiment in the case of the photoionization cross section, but only qualitative agreement with experiment and with other theoretical calculations is obtained in the case of the photoelectron angular distribution due to the difficulty …

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Four-Color And Hβ Photometry Of Stars In The Galactic Cluster Ngc 6087, Edward G. Schmidt Feb 1980

Four-Color And Hβ Photometry Of Stars In The Galactic Cluster Ngc 6087, Edward G. Schmidt

Edward Schmidt Publications

Four-color and Hβ photometry has been obtained for 16 stars in the open cluster NGC 6087. Based on this photometry the membership of these stars in the cluster is discussed. Using stars which appear to be members a color excess of E(b – y) = 0m.23 and a distance modulus of (V0 – Mv) = 9m.60 are derived. This distance modulus is about 0m.4 less than previous values and indicates a lower luminosity for the Cepheid member, S Nor, than is currently accepted.

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Untitled (Subject: Energy), Richard C. Heyser Jan 1980

Untitled (Subject: Energy), Richard C. Heyser

Unpublished Writings

Fundamental energy relations are explored as a basis for the measurement of physical systems. By considering finite dimensional observations in linear Hilbert space it is shown that a necessary and sufficient condition for the conservation of energy is the partitioning of any observation of that energy into two components which will be related through the Hilbert transform. The consequence of this relationship is demonstrated for the equilibrium storage of energy, point-wave duality in measurements, significance of complex representations involving circular form, the meaning of minimum phase and all-pass properties, and the introduction of new measurement characterizations such as the energy-time …

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The Two Parts Of Energy, Richard C. Heyser Jan 1980

The Two Parts Of Energy, Richard C. Heyser

Unpublished Writings

In this paper, Richard C. Heyser explains the theories behind measuring sound by discussing its energy. Using what he calls abstract geometry, Heyser argues that measuring the transfer properties (that is, pressure and velocity) of sound's energy aids in the discovery of its amplitude and phase (or in-phase and quadrature).

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Four-Color And Hβ Photometry Of Stars In The Galactic Cluster Ngc 129, Edward G. Schmidt Jan 1980

Four-Color And Hβ Photometry Of Stars In The Galactic Cluster Ngc 129, Edward G. Schmidt

Edward Schmidt Publications

Four-color and photometry has been obtained for 22 stars in the field of the open cluster NGC 129. Based on this photometry, the membership of these stars in the cluster is discussed and it is found that many are field stars. The color excesses for cluster members obtained here range from E(b – y) = 0.207 to 0.513 and are larger than those found from previous UBV photometry. It has been suggested that this cluster contains a nonvariable Cepheid strip star. However, the present reddening places this star at the edge of the instability strip. A true …

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Theoretical Lattice-Dynamical Studies Of The Incommensurate Phase Transformation In K2Seo4, M. S. Haque, John R. Hardy Jan 1980

Theoretical Lattice-Dynamical Studies Of The Incommensurate Phase Transformation In K2Seo4, M. S. Haque, John R. Hardy

John R. Hardy Papers

We have made detailed lattice-dynamical studies of the origin of the incommensurate phase transition in potassium selenate. These were based on a rigid-ion model with Coulomb interactions, and also short-range interactions between restricted numbers of close neighbors. The associated short-range force constants were determined using the static equilibrium conditions for the crystal and the observed Raman frequencies. The calculations were made for the room temperature structure using the quasiharmonic approximation in which the effects of varying temperature were simulated by varying the short-range force constants. In this way we were able to show that the crystal has a low-frequency optic …

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Plasma Line Measurements At Chatanika With High-Speed Correlator And Filter Bank, W. Kofman, Vincent B. Wickwar Jan 1980

Plasma Line Measurements At Chatanika With High-Speed Correlator And Filter Bank, W. Kofman, Vincent B. Wickwar

All Physics Faculty Publications

In the spring and fall of 1978 we made an extensive series of plasma line and correlative observations with the Chatanika incoherent scatter radar. To make these measurements, we greatly modified the radar receiving system. In addition to enlarging the plasma line filter bank the most significant change was the incorporation of a high-speed correlator provided by the French. This was the first use of a correlator in a monostatic radar to obtain the intensity spectra of naturally occurring plasma lines. In this paper we develop the signal-processing theory that we use to obtain the plasma line intensities from these …

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High-Latitude Convection: Comparison Of A Simple Model With Incoherent Scatter Observations, Jan Josef Sojka, J. C. Foster, W. J. Raitt, Robert W. Schunk, J. R. Doupnik Jan 1980

High-Latitude Convection: Comparison Of A Simple Model With Incoherent Scatter Observations, Jan Josef Sojka, J. C. Foster, W. J. Raitt, Robert W. Schunk, J. R. Doupnik

All Physics Faculty Publications

We have compared a simple model of plasma convection at high latitudes with data obtained from simultaneous measurements made by the incoherent scatter facilities at Chatanika, Alaska and Millstone Hill, Massachusetts in June 1978 during moderately disturbed conditions. The measured horizontal plasma drift velocities were averaged for four days to emphasize gross features of the convection pattern and reduce the effects of substorms. The convection model includes the offset of 11.5° between the geographic and geomagnetic poles, the tendency of plasma to corotate about the geographic pole, and a constant dawn/dusk magnetospheric electric field mapped to a circle about a …

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A Comparison Of Model Predictions For Plasma Convection In The Northern And Southern Polar Regions, Jan Josef Sojka, W. J. Raitt, Robert W. Schunk Jan 1980

A Comparison Of Model Predictions For Plasma Convection In The Northern And Southern Polar Regions, Jan Josef Sojka, W. J. Raitt, Robert W. Schunk

All Physics Faculty Publications

We have presented model calculations to show how the plasma flow distributions in the northern and southern polar regions differ when viewed from a geographic inertial frame. This reference frame was selected because it is the natural frame for geophysical plasma flow measurements, there being well-known velocity corrections for either satellite or ground-based observations. Although the magnetic invariant latitude, magnetic local time reference frame is better suited to studying magnetospheric processes, a transformation from the geographic inertial frame to this magnetic frame requires both a spatial and velocity transformation, and since the latter correction has generally been neglected, we prefer …

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A Graphical Method For Calculating First Order Transition Matrices For Open-Shell Atoms In The Random Phase Approximation, Anthony F. Starace, Siamak Shahabi Jan 1980

A Graphical Method For Calculating First Order Transition Matrices For Open-Shell Atoms In The Random Phase Approximation, Anthony F. Starace, Siamak Shahabi

Anthony F. Starace Publications

A graphical procedure is presented for calculating first order transition matrices for a general (open-shell) atom. The first order transition matrix may be used to calculate matrix elements of a general one-body operator of rank λ in orbital space and σ in spin space. In the random phase approximation we obtain a set of N + N′ coupled differential equations for N final state radial functions and N′ initial state radial functions which completely determine the first order transition matrix for an atomic system having N final state channels. (The relation of N′ to N is dependent on the atomic …

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Angular And Energy Distribution Of Electrons From 15- To 150-Kev H0+He Collisions, M. Eugene Rudd, J. S. Risley, J. Fryar, R. G. Rolfes Jan 1980

Angular And Energy Distribution Of Electrons From 15- To 150-Kev H0+He Collisions, M. Eugene Rudd, J. S. Risley, J. Fryar, R. G. Rolfes

M. Eugene Rudd Publications

An electrostatic analyzer positioned at various angles has been used to measure absolute values of cross sections for electron production in collisions of neutral hydrogen atoms with helium as a function of the angle and energy of the ejected electrons. These cross sections are compared with corresponding ones for proton and electron impact to infer the mechanisms of electron production. A prominent peak in the energy distribution due to electron loss from the projectile occurs at an electron velocity equal to that of the projectile. At very low electron energies the similarity of the energy distribution to that due to …

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Design And Use Of A Computerized Test Generating Program, Edward Schaefer, Laurence A. Marschall Jan 1980

Design And Use Of A Computerized Test Generating Program, Edward Schaefer, Laurence A. Marschall

Physics and Astronomy Faculty Publications

An easy-to-use set of programs for the computerized generation of multiple-choice and easy examinations in an introductory astronomy course is described. The programs allow the user to establish files of test questions and to rapidly assemble printed copies of examinations suitable for photocopying. Written in ALGOL for a Burroughs B6700 computer, the programs can, in principle, be implemented on large mainframe computers or on microcomputers of a size increasingly available to physics departments. The advantages and costs of computerized test generation are discussed.

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Hall-Coefficient And Resistivity At High Pressure In 1t-Tas2, Paul D. Hambourger, F. J. Disalvo Jan 1980

Hall-Coefficient And Resistivity At High Pressure In 1t-Tas2, Paul D. Hambourger, F. J. Disalvo

Physics Faculty Publications

No abstract provided.

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Characterization Of Phase Transitions In Vanadium Deuterides, R. L. Tober, Gust Bambakidis Jan 1980

Characterization Of Phase Transitions In Vanadium Deuterides, R. L. Tober, Gust Bambakidis

Physics Faculty Publications

No abstract provided.

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Total Penning Ionization Cross Sections Of Cd And Zn For He(2 ³S1) Atoms, D. W. Fahey, William F. Parks, Laird D. Schearer Jan 1980

Total Penning Ionization Cross Sections Of Cd And Zn For He(2 ³S1) Atoms, D. W. Fahey, William F. Parks, Laird D. Schearer

Physics Faculty Research & Creative Works

The total Penning ionization cross sections for Cd and Zn for He(2 3S1) atoms have been measured. The method used was that of Penning ion collection from a vapor cell through which a He(2 3S1) beam was passed. The beam energy was 66 meV with a velocity spread of 45%. The measured cross sections were 106(±22) and 35(±7) Å2 for the Cd and Zn targets, respectively. © 1980 American Institute of Physics.

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Injection-Locked Dye Laser Pumped By A Xenon-Lon Laser, E. R. Carney, D. W. Fahey, Laird D. Schearer Jan 1980

Injection-Locked Dye Laser Pumped By A Xenon-Lon Laser, E. R. Carney, D. W. Fahey, Laird D. Schearer

Physics Faculty Research & Creative Works

Injection locking of a dye laser is reported for a 4-minor ring-cavity dye User pumped by a xenon-ion laser. Both a He-Ne laser and tunable CW dye laser were used as the injection sources. Copyright © 1980 by The Institute of Electrical and Electronics Engineers, Inc.

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Large-Angle Electron-Photon Coincidence Experiment In Atomic Hydrogen, E. Weigold, L. Frost, K. (Kaare) J. Nygaard Jan 1980

Large-Angle Electron-Photon Coincidence Experiment In Atomic Hydrogen, E. Weigold, L. Frost, K. (Kaare) J. Nygaard

Physics Faculty Research & Creative Works

1s-2p excitation in hydrogen has been studied by observing the angular correlation of Lyman photons detected in coincidence with inelastically scattered electrons at 54.4 eV incident energy. The electron scattering angles ranged from 10°to 133°; the results at scattering angles larger than 20°cannot be explained by currently available theories. © 1980 The American Physical Society.

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Solid State Phase Transitions And Molecular Reorientation In Ortho-Carborane And Para-Carborane: An Isomer Effect, Peter A. Beckmann, Amos J. Leffler Jan 1980

Solid State Phase Transitions And Molecular Reorientation In Ortho-Carborane And Para-Carborane: An Isomer Effect, Peter A. Beckmann, Amos J. Leffler

Physics Faculty Research and Scholarship

The proton nuclear spin-lattice relaxation times at 30 MHz have been measured for ortho- and paracarborane between 170 and 310 K and between 210 and 320 K, respectively. Para-carborane undergoes solid-solid transitions at about 300 and 238 K while the ortho isomer shows only one transition at about 265 K. The details of the phase transitions are discussed and molecular reorientation in the isomers is compared.

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Proton Spin-Lattice Relaxation In Meta-Carborane, Peter A. Beckmann, Armin Wendel Jan 1980

Proton Spin-Lattice Relaxation In Meta-Carborane, Peter A. Beckmann, Armin Wendel

Physics Faculty Research and Scholarship

No abstract provided.

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A Deuterium Nuclear Magnetic Resonance Study Of Chain Disorder In Lamellar Potassium Palmitate: The Effect Of Long And Short Chain Guests, Peter A. Beckmann, E. E. Burnell, M. A. Heldman, K. R. Northey, T. P. Higgs Jan 1980

A Deuterium Nuclear Magnetic Resonance Study Of Chain Disorder In Lamellar Potassium Palmitate: The Effect Of Long And Short Chain Guests, Peter A. Beckmann, E. E. Burnell, M. A. Heldman, K. R. Northey, T. P. Higgs

Physics Faculty Research and Scholarship

The deuterium magnetic resonance spectra of lamellar phases of host perdeuterated potassium palmitate mixed with varying amounts of guest protiated potassium octanoate and behenate and 86.3 mol% D2O are reported. At higher temperatures, the short chain guests give rise to more fluidity and the long chain guests give rise to less fluidity towards the end of the host chain. At low temperatures there are changes in the interaction between the polar head group and the water which depend on sample composition. The transition from the lamellar phase to the low temperature gel phase is investigated and in some …

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Electronic Properties Of Molybdenum-Iron-Sulfur-Clusters: Approaches To The Molybdenum Site In Nitrogenase, Richard B. Frankel, T. E. Wolff, P. P. Power, R. H. Holm Jan 1980

Electronic Properties Of Molybdenum-Iron-Sulfur-Clusters: Approaches To The Molybdenum Site In Nitrogenase, Richard B. Frankel, T. E. Wolff, P. P. Power, R. H. Holm

Physics

No abstract provided.

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Comment On “Cancellation Of Internal Forces”, Harry A. Brown Jan 1980

Comment On “Cancellation Of Internal Forces”, Harry A. Brown

Physics Faculty Research & Creative Works

No abstract provided.

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Nonequilibrium Thermodynamics Of Fuel Cells: Heat Release Mechanisms And Voltage, Gerald Wilemski Jan 1980

Nonequilibrium Thermodynamics Of Fuel Cells: Heat Release Mechanisms And Voltage, Gerald Wilemski

Physics Faculty Research & Creative Works

Nonequilibrium thermodynamics is used to analyze the spatial distribution of heat release mechanisms occurring in fuel cells operating under load in nonisothermal steady states. Novel contributions to heat release in the bulk electrolyte are found which are analogous to Peltier and Thomson effects in metallic conductors. Expresions for the heat release at individual electrodes are presented. An equation for the voltage of these cells is also derived. © 1980 American Institute of Physics.

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Autooscillations And Nonlinear Anelasticity, Manfred Wuttig, Tetsuro Suzuki Jan 1980

Autooscillations And Nonlinear Anelasticity, Manfred Wuttig, Tetsuro Suzuki

Materials Science and Engineering Faculty Research & Creative Works

In conclusion it can be stated that a novel phenomenon, a mechanical auto oscillation, has been described theoretically and shown to exist experimentally. These auto oscillations occur when a nonlinear anelastic solid is forced into large amplitude oscillations in the vicinity of a martensitic transformation. They manifest themselves as a low frequency auto modulation of the a martensitic transformation. They manifest themselves as low frequency auto modulation of the forced vibration of such a solid. © 1980.

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More On Calculators In Beginning Physics Courses, Harry A. Brown Jan 1980

More On Calculators In Beginning Physics Courses, Harry A. Brown

Physics Faculty Research & Creative Works

No abstract provided.

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