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Articles 1 - 30 of 64
Full-Text Articles in Physics
Nickel Carbide: Its Formation And Characterization By Transmission Electron Diffraction, Auger Electron Spectroscopy And Electron Spectroscopy For Chemical Analysis, J. Kleefeld, L. L. Levenson
Nickel Carbide: Its Formation And Characterization By Transmission Electron Diffraction, Auger Electron Spectroscopy And Electron Spectroscopy For Chemical Analysis, J. Kleefeld, L. L. Levenson
Physics Faculty Research & Creative Works
Nickel carbide (NiC3) films are formed by the carburization of nickel films in CO at 350°C. The presence of Ni3C is demonstrated by transmission electron diffraction. The carbon Auger electron signal of Ni3C is identical with the carbon Auger spectra attributed to Ni3C by previous authors. The position of the C 1s electron spectroscopy for chemical analysis peak is within 1 eV of the C 1s peak produced by graphite. The grain size of polycrystalline Ni3C is significantly larger than the grain size of the nickel film from which it is grown. © 1979.
Rates Of Dissociative Attachment Of Electrons To Excited H2 And D2, J. M. Wadehra
Rates Of Dissociative Attachment Of Electrons To Excited H2 And D2, J. M. Wadehra
Physics and Astronomy Faculty Research Publications
Calculations are reported of the contributions of the lowest 2Σ+ u and 2Σ+ g resonant states to the rates of dissociative attachment of electrons to H2 and D2. For all electron temperatures, the rate is significantly enhanced by vibrational and rotational excitation of the initial molecule. Typically, for an electron temperature of 1.5 eV, the attachment rates for various (v, J) levels are, in cm3 sec−1, 5.4×10−15 for (0,0), 7.2×10−11 for (0,20), and 7.8×10−9 for (8,0), for H2; and 4.5×10−17 for (0,0), 1.4×10−14 for (0,20), and 6.0×10−9 for (11,0), for D2.
Comment On The Negative Ion States Of Fluorobenzenes, K.D. Jordan, Paul Burrow
Comment On The Negative Ion States Of Fluorobenzenes, K.D. Jordan, Paul Burrow
Paul Burrow Publications
It is contended that several assignments given by the model employed by Frazier et al1 should be reconsidered especially of the anion states aniline phenol and anisole. The symmetry assignments of the anion states of fluorobenzene and p difluorobenzend as given by this model are incorrect.
Magnetic Ordering And Exchange Interactions In The Rare-Earth Gallium Compounds R Ga2, T.-H. Tsai, David J. Sellmyer
Magnetic Ordering And Exchange Interactions In The Rare-Earth Gallium Compounds R Ga2, T.-H. Tsai, David J. Sellmyer
David Sellmyer Publications
Magnetic ordering and indirect exchange interactions were studied in the series of hexagonal rare-earth intermetallic compounds R Ga2, where R denotes Ce, Pr, Nd, Gd, Tb, Dy, Ho, and Er. The magnetic susceptibility (χ) of polycrystalline samples was measured at low fields, from 1.5 K to about 300 K; the magnetization (M) versus applied magnetic field (H) of these polycrystalline samples and a HoGa2 single crystal was measured up to 80 kOe at low temperatures; the resistivities (ρ) of CeGa2, GdGa2, DyGa2, and HoGa2 were measured …
Determination Of Energy Levels & Oscillator Strengths Of 2% Nd:Y2o3, Kung-Chuan Shao
Determination Of Energy Levels & Oscillator Strengths Of 2% Nd:Y2o3, Kung-Chuan Shao
Masters Theses & Specialist Projects
The absorption spectrum of 2% Nd:Y2O3 has been obtained at room termperature. It has been used to determine the crystalline energy levels.
Through counting the number of Stark components, degeneracies have been determined for oscillator strength calculations.
Overlapping absorption lines were analyzed into their components.
Oscillator strengths have been measured for those well-identified and analyzed transitions in the variable and near ultraviolet regions of the 2% Nd:Y2O3 absorption spectrum.
The Hanle Effect In Penning-Excited Ions, D. W. Fahey, William F. Parks, Laird D. Schearer
The Hanle Effect In Penning-Excited Ions, D. W. Fahey, William F. Parks, Laird D. Schearer
Physics Faculty Research & Creative Works
A thermal beam of helium (23S1) metastable atoms was used to excite coherently the 2P3/2 levels of Ca, Sr and Ba in a Penning ionizing collision. The coherent excitation of the ions appears as a linear polarization of the optical emission from the excited ions. The degree of linear polarization is 5.5, 3.5 and 0.5% for Ca, Sr and Ba, respectively, with the polarization parallel to the beam direction. Hanle effect signals from the 2P3/2 level of Sr were observed and the radioactive decay rate measured.
Conductive Strontium Titanate Layers Produced By Boron-Ion Implantation, Connie M. Cooper, P. S. Nayar, Edward Boyd Hale, Robert Gerson
Conductive Strontium Titanate Layers Produced By Boron-Ion Implantation, Connie M. Cooper, P. S. Nayar, Edward Boyd Hale, Robert Gerson
Physics Faculty Research & Creative Works
The ion implantation of boron has been found to be an effective method for increasing the conductivity of strontium titanate. A highly conductive layer was formed by implantations at doses of 3.6x1016 to 1.0x1017 ions/cm2, using an accelerating voltage of 100 kV, corresponding to a boron range of about 300 nm. The conductivity of the implanted layer was found to be further enhanced by about four orders of magnitude after annealing at 225 °C. The surface resistivity attained was typically 1000 Ω/square at room temperature. The resistance increased with rising temperature between 77 and 500 K. All samples were found …
Electron Drift Velocities In N2, Co2, And (N 2+Co2) Laser Mixtures, Rafael A. Sierra, Howard L. Brooks, Kaare J. Nygaard
Electron Drift Velocities In N2, Co2, And (N 2+Co2) Laser Mixtures, Rafael A. Sierra, Howard L. Brooks, Kaare J. Nygaard
Physics Faculty Research & Creative Works
A time-of-flight technique has been used to obtain electron drift velocities in N2, CO2, and N2-CO2 mixtures covering the E/N range 3-93 Td. In the case of the pure gases, excellent agreement with previous work is obtained over the entire E/N range. The mixtures, which are of laser importance, have not been studied previously.
Low-Energy Collisions Of D+ With D And He++ With He, J. M. Wadehra
Low-Energy Collisions Of D+ With D And He++ With He, J. M. Wadehra
Physics and Astronomy Faculty Research Publications
Quantum-mechanical calculations for differential cross sections and various transport cross sections describing the thermal-energy collisions of D+ with D and He2+ with He are presented. Lowest-order Viehland-Mason theory is used to calculate mobility of D+ in D. The zero-field mobility at 77, 303, and 10000 K is, in units of cm2V−1s−1, 10.5, 7.0, and 2.1, respectively.
Dissociative Attachment And Vibrational Excitation In Low-Energy Collisions Of Electrons With H2 And D2, J. N. Bardsley, J. M. Wadehra
Dissociative Attachment And Vibrational Excitation In Low-Energy Collisions Of Electrons With H2 And D2, J. N. Bardsley, J. M. Wadehra
Physics and Astronomy Faculty Research Publications
A semiempirical analysis is made of the contributions of the two lowest resonant states to dissociative attachment and vibrational excitation in low-energy collisions of electrons with H2 and D2. The resonance models are based both on ab initio calculations and on fits to experimental data. The dissociative-attachment cross section near threshold is enhanced significantly by vibrational or rotational excitation of the initial molecule. Near 10 eV, contributions from both resonances are required to explain the observed cross sections for vibrational excitation.
Spin-Glass-Like Behavior In Very Dilute Pdfe At Very Low Temperatures, Richard A. Webb, G. W. Crabtree, J. J. Vuillemin
Spin-Glass-Like Behavior In Very Dilute Pdfe At Very Low Temperatures, Richard A. Webb, G. W. Crabtree, J. J. Vuillemin
Faculty Publications
Measurements of the electrical resistivity of palladium, residual resistivity ratio ∼22 500, containing 1.7 ppm of Fe have been made from 5.5 K to 1.8 mK. 15 Hz ac susceptibility measurements from 1 K to 1.8 mK together with the resistivity data suggest that a transition into a spin-glass state occurs near 7 mK.
Photoionization Of Chalcogen And Halogen Atoms: Cross Sections And Angular Distributions, Steven T. Manson, Alfred Msezane, Anthony F. Starace, Siamak Shahabi
Photoionization Of Chalcogen And Halogen Atoms: Cross Sections And Angular Distributions, Steven T. Manson, Alfred Msezane, Anthony F. Starace, Siamak Shahabi
Anthony F. Starace Publications
The authors present a survey of the photoionization cross sections and photoelectron angular distributions for the outer p subshell of the chalcogen atoms O, S, Se, and Te and the halogen atoms F, Cl, Br, and I. Results are presented in the Hartree-Fock approximation as well as in the central-potential-model approximation. An extensive analysis and comparison of the results obtained is presented which finds that exchange-interaction effects are strongest for the n=3 row elements.
Brownian Motion In A Flowing Fluid, John D. Ramshaw
Brownian Motion In A Flowing Fluid, John D. Ramshaw
Physics Faculty Publications and Presentations
A phenomenological theory is developed for Brownian motion in a flowing incompressible fluid. The Brownian particles are regarded as an ideal gas subject to a position- and time-dependent force field that represents interactions with the host fluid. This approach immediately leads to deterministic partial differential equations of motion for the Brownian particles. These equations are then examined in the limit of large friction, in which they imply an expression for the diffusional mass flux of Brownian particles. This expression is a sum of terms representing concentration, forced, thermal, and pressure diffusion. Comparisons are made with earlier work, and with the …
Doubly Differential Cross Sections For Proton-Impact Ionization Of Argon, Don H. Madison, Steven Trent Manson
Doubly Differential Cross Sections For Proton-Impact Ionization Of Argon, Don H. Madison, Steven Trent Manson
Physics Faculty Research & Creative Works
Proton-impact-ionization cross sections for argon which are differential in the energy and angle of the ejected electron have been calculated within the framework of the Born approximation using both Hartree-Slater and Hartree-Fock wave functions for the ejected electron. Results of the two types of calculations are compared with each other and with experiment. Differential cross sections for all five sub shells of argon are examined and particular attention is given to some interesting features of the K-shell cross sections. The range of applicability of the theoretical models is discussed.
The Wavelength Dependence Of Herpes Simplex Viral Inactivation & Ultraviolet Enhanced Reactivation, Richard Detsch
The Wavelength Dependence Of Herpes Simplex Viral Inactivation & Ultraviolet Enhanced Reactivation, Richard Detsch
Masters Theses & Specialist Projects
The degrees of Ultraviolet Enhanced Reactivation (UVR) by mammalian cells of Heroes simplex virus inactivated by different wavelengths of far ultraviolet radiation were measure'. The wavelength dependence of UVR is presented for the wavelength region 238 nm to 297 nm. The shape of the UVR curve suggests that virus directed repair is less dependent on the wavelength of UV radiation than are cellular repair mechanisms. The wavelength dependence of Herpes simplex inactivation by far UV radiation is also presented. The shape of the virus inactivation curve suggests the involvement of both DNA and protein.
Physical Consequences Of Anomalies In Nonlocal Potential Problems, L. L. Foldy, James A. Lock
Physical Consequences Of Anomalies In Nonlocal Potential Problems, L. L. Foldy, James A. Lock
Physics Faculty Publications
An s-wave two-body separable potential may give rise to several phenomena which are absent for nonsingular local potentials. We examine the physical implications of a well known example of such phenomena, the continuum bound state, as well as of two lesser known anomalies, the so-called positive energy spurious state and negative energy bound states with improper long-range behavior. By examining these anomalies in light of Levinson's theorem, Wigner's phase shift inequality, and the effect of a perturbation on the anomalous states by their insertion in a three-body scattering situation, we find in agreement with previous studies that the continuum bound …
Magnetically Dilute Metallic Glasses. Ii. 4F Moments, G.R. Gruzalski, David J. Sellmyer
Magnetically Dilute Metallic Glasses. Ii. 4F Moments, G.R. Gruzalski, David J. Sellmyer
David Sellmyer Publications
Magnetic-susceptibility and high-field magnetization measurements are presented for amorphous Zr40Cu600-xMx (M denoting Gd and Tb), with x ranging from zero to ten. Effective moments of magnetic solutes were determined by fitting susceptibility data to the Curie-Weiss expression. The moments of Gd and Tb are very close to those expected for trivalent ions and the paramagnetic Weiss temperatures are positive. Saturation did not occur in any of the samples, even at 80 kOe and 1.3 K; however, the alloys containing Gd approached normalized magnetization values of unity. High-field hysteresis loops were used to obtain the …
Magnetically Dilute Metallic Glasses. I. 3D Moments, G.R. Gruzalski, David J. Sellmyer
Magnetically Dilute Metallic Glasses. I. 3D Moments, G.R. Gruzalski, David J. Sellmyer
David Sellmyer Publications
Magnetic-susceptibility and high-field magnetization measurements are presented for amorphous Zr40Cu50M10 (M denoting Fe, Mn) and Nb50Ni50-xFex, with x ranging from zero to about ten. Curie-Weiss fits to the susceptibility data were made to determine effective moments peff and paramagnetic Weiss temperatures, ⊖. The small values of peff suggest the presence of moment instabilities depending on local environment, and the negative ⊖ values suggest antiferromagnetic local-moment-conduction-electron interactions. The Fe alloys develop hysteresis at low temperatures indicating the presence of a magnetically ordered state. These alloys can be …
Direct Relation Between Fresnel’S Interface Reflection Coefficients For The Parallel And Perpendicular Polarizations, R. M.A. Azzam
Direct Relation Between Fresnel’S Interface Reflection Coefficients For The Parallel And Perpendicular Polarizations, R. M.A. Azzam
Electrical Engineering Faculty Publications
We have found a significant relation, rp = rs (rs -cos2ϕ)/(1-rs cos2ϕ), between Fresnel’s interface complex-amplitude reflection coefficients rp and rs for the parallel (p) and perpendicular (s) polarizations at the same angle of incidence ϕ. This relation is universal in that it applies to reflection at all interfaces between homogeneous isotropic media collectively and, of course, throughout the electromagnetic spectrum. We investigate the properties of this function, rp = f (rs), and its inverse,rs = g (rp), as …
Photometric Measurements Of Thin Tracks In Nuclear Emulsion, Robert Katz
Photometric Measurements Of Thin Tracks In Nuclear Emulsion, Robert Katz
Robert Katz Publications
Difficulties observed in the application of track theory to CNO particles are attributed to problems in the application of a light scattering correction in microphotometry.
Relations Between Amplitude Reflectances And Phase Shifts Of The P And S Polarizations When Electromagnetic Radiation Strikes Interfaces Between Transparent Media, R. M.A. Azzam
Electrical Engineering Faculty Publications
No abstract provided.
Ab Initio Treatment Of Final-State Spin-Orbit Interactions: Photoionization Of The 6S Electron In Cesium, Keh-Ning Huang, Anthony F. Starace
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
Ab initio theoretical calculations are presented for the cross section, photoelectron angular distribution, and photoelectron spin polarization resulting from photoionization of the 6s electron of cesium. Starting from an initial basis of nonrelativistic Hartree-Fock wave functions, the effect of final-state spin-orbit interaction in the Breit-Pauli approximation is treated exactly. The effect of core relaxation is also examined. Our calculated results agree with recent experimental measurements of the photoionization cross section and the photoelectron spin polarization. Comparison is made with other theoretical calculations. Finally, the length form of the electric dipole interaction operator is shown to be consistent with gauge invariance …
Resonant Contributions To Single Charge Transfer Between He++ And He, J. N. Bardsley, James S. Cohen, J. M. Wadehra
Resonant Contributions To Single Charge Transfer Between He++ And He, J. N. Bardsley, James S. Cohen, J. M. Wadehra
Physics and Astronomy Faculty Research Publications
Energy levels and lifetimes are calculated for the resonant states that are important in radiative single charge transfer in He2+-He collisions at thermal energies. The resonant contribution to the charge-transfer rate decreases with increasing temperature and is approximately 12% of the total rate at 300 K.
Magnetic Properties Of Iron-Doped Layer-Structure Dichalcogenides , S.J. Hillenius, R.V. Coleman, E.R. Domb, David J. Sellmyer
Magnetic Properties Of Iron-Doped Layer-Structure Dichalcogenides , S.J. Hillenius, R.V. Coleman, E.R. Domb, David J. Sellmyer
David Sellmyer Publications
Magnetic-susceptibility measurements have been made on dilute excess Fe alloys of the layer-structure crystals TaSe2, NbSe2, and TaS2. The 2H selenides show local-moment formation and obey a Curie-Weiss law in the range 300-30 K with effective moments in the range (2.5-4.5)μB. For 2H-FexTaSe2 a strong susceptibility maximum is observed at low temperature and at low fields the maximum has a cusplike shape characteristic of a "spin-glass" type transition. The temperature of the maximum scales approximately linearly with Fe concentration and reaches 13 K for x=0.10. …
Simulative Investigation Of The Detection Of Modes Of Luminosity Variation In Astrophysical Sources, James Collins
Simulative Investigation Of The Detection Of Modes Of Luminosity Variation In Astrophysical Sources, James Collins
Masters Theses & Specialist Projects
Five astronomical data analysis methods were evaluated, using computer simulation techniques, for minimum detection levels, periodicity detection, and parameter estimation sensitivities. The evaluation of these methods was accomplished using three basic waveforms with the addition of ten “random” noise samples from a Gaussian distribution of known parameters. The chi-square and t-test methods were evaluated in detecting low-amplitude variability and brightness level shifts. Results indicate both methods have a strong dependence on the estimation of the standard deviation (σ) where a 0.1 change in σ will affect detection rates by ten to twenty-five percent at the ninety-five percent confidence level. The …
Effect Of Magnetic Fields On Drug Induced Contractility And Mortality In Spirostomum, Angela Ripamonti, Richard B. Frankel, E. M. Ettienne
Effect Of Magnetic Fields On Drug Induced Contractility And Mortality In Spirostomum, Angela Ripamonti, Richard B. Frankel, E. M. Ettienne
Physics
The influence of homogeneous magnetic fields up to 5.5 T on contractile frequency and mortality in the ciliate protozoan spirostomum ambiguum stimulated by 2,2′ PDS is reported. Magnetic fields are observed to decrease contractile frequency and to significantly increase mortality.
Electronic Properties And Superconductivity Of Zr-Pd Glasses, G.R. Gruzalski, J.A. Gerber, David J. Sellmyer
Electronic Properties And Superconductivity Of Zr-Pd Glasses, G.R. Gruzalski, J.A. Gerber, David J. Sellmyer
David Sellmyer Publications
Electrical-resistivity measurements between 1.4 and 300 K and room-temperature magnetic-susceptibility measurements were performed on the metallic glasses ZrxPd1-x, for x=0.59, 0.63, 0.67, and 0.70. The samples, prepared by a modified hammer-anvil technique, exhibit negative temperature coefficients of the resistivity at temperatures from about 10 to 300 K. These data can be understood in terms of the extended Ziman theory if it is assumed that Zr and Pd contribute about 2 and 1 conduction electrons, respectively. Assuming that the magnetic susceptibility is a qualitative measure of the electronic density of states at the Fermi level, N …
Transformation Of Fresnel’S Interface Reflection And Transmission Coefficients Between Normal And Oblique Incidence, R. M.A. Azzam
Transformation Of Fresnel’S Interface Reflection And Transmission Coefficients Between Normal And Oblique Incidence, R. M.A. Azzam
Electrical Engineering Faculty Publications
If w denotes an interface Fresnel reflection or transmission coefficient for s- or p-polarized light at an oblique angle of incidence ø, and z denotes the same coefficient at normal incidence, we find that w is an analytic function of z, w = ƒ(z), that depends on ø but not on the specific optical properties of the two media on both sides of the interface. All four functions that correspond to the four distinct Fresnel coefficients and their inverses are determined. We single out for detailed examination, as an example, the relationship between the reflection of s -polarized light at …
Type Conversion In Electron‐Irradiated Gaas, J. W. Farmer, David C. Look
Type Conversion In Electron‐Irradiated Gaas, J. W. Farmer, David C. Look
Physics Faculty Publications
The unambiguous type conversion of GaAs by electron irradiation is reported here for the first time. Several high‐quality n‐type vapor‐phase epitaxial layers (ρ?3 Ω cm and μ?7000 cm2/V sec at 300 K) were converted by 1‐MeV electrons to high‐quality p‐type layers (ρ?30 Ω cm and μ?400 cm2/V sec). Temperature‐dependent Hall‐effect data show energy levels at 0.5, 0.3, and about 0.1 eV above the valence band. Evidence is presented to indicate that the failure of some of our samples (and, perhaps, other samples reported in the literature) to convert to low‐r …
Atomic Hydrogen In A Uniform Magnetic Field: Low-Lying Energy Levels For Fields Below 109 G, Anthony F. Starace, Gary L. Webster
Atomic Hydrogen In A Uniform Magnetic Field: Low-Lying Energy Levels For Fields Below 109 G, Anthony F. Starace, Gary L. Webster
Anthony F. Starace Publications
The wave function for an electron in combined Coulomb and uniform magnetic fields is expanded in oblatespheroidal angle functions. The resulting Schrödinger equation for the radial function is solved for the energy levels by means of two different adiabatic approximations, which yield rigorous lower and upper bounds on the lowest exact energy levels for each symmetry state of the system. Results are presented for the level and binding energies of hydrogenic 1s, 2s, and 2p levels for magnetic fields in the range 107≤B≲1011 G and compared with results of other …