Digital Commons Network^™

Water And Ice Nucleation Sites From Ion Implantation Of Silicon, William H. Stlnebaugh, Don M. Sparlin, James L. Kassner

Physics Faculty Research & Creative Works

Ion implantation has a substantial effect on the heterogeneous nucleation of water and ice. An enhancement of water nucleation and a suppression of ice nucleation occurred for samples of silicon implanted with ions of various species and dosage. These effects were noticeable only for samples implanted with ion doses approaching or exceeding the critical dose necessary to produce amorphous silicon. The behavior of the water droplet and ice crystal growth can be related to the amount of ion produced damage to the substrate surface. The nature of the damage can be controlled by variation of the incident ion species, dose, …

Navigational Compass In Magnetic Bacteria, Richard B. Frankel, R. P. Blakemore

Physics

Magnetotactic bacteria that orient and swim in a preferred direction in the geomagnetic field contain sufficient single domain magnetite to constitute a biomagnetic compass.

Forbidden Lines Of Np^Q Ions. I. Detailed Balance And Line Intensity Ratios, Menas Kafatos, J. P. Lynch

Mathematics, Physics, and Computer Science Faculty Articles and Research

Ground state forbidden transitions of np^q ions of C, N, 0, Ne, Mg, Si, S, and Fe can provide important information on the state of cosmic ionized gases. Wavelengths of these lines are in the far- and near-UV visible and near-- and far-IR regions of the spectrum. The line intensity ratios of particular transitions in q = 2, 4 ions can provide information on the temperature of the gas and in q = 3 ions information on the density of the gas. In the present work we have tabulated the line intensities of 95 transitions of these ions, which include …

Effects Of Beam Polarization On Λ And K0 Inclusive Production In Pp Interactions At 12 Gev/C, R. L. Eisner, William J. Fickinger, J. A. Malko, D. K. Robinson, V. A. Sreedhar

Faculty Scholarship

Inclusive production of Λ and K0 in pp interactions at 12 GeV/c has been studied in an exposure of the Argonne National Laboratory 12-foot bubble chamber to a 50% transversely polarized proton beam. Beam-polarization-induced asymmetries are observed for both K0 and Λ production in the forward direction.

The Cepheid Luminosity Scale, Edward G. Schmidt

Edward Schmidt Publications

The distance moduli of galactic clusters containing classical Cepheids are being redetermined using the four-color and Hβ photometric system. The results for four clusters are presented here and it is found that the distance moduli are smaller than previous values. Possible reasons for this discrepancy are discussed.

Continental Drift, Tectonics, And Joshua, Joel W. Block

Physics Faculty Publications

The Bible has served as a source of spiritual inspiration for many centuries. It has been used as a text in the academic disciplines of history, geography, archeology, literature, law, language, and health, as well as in theology. Yet this multipurpose manuscript has been virtually ignored as an earth science reference It is this writer's intent to demonstrate the Bible's value as a geological resource.

Determiningeons : A Computer Program For Approximating Lie Generators Admitted By Dynamical Systems, Gregory G. Nagao

University of the Pacific Theses and Dissertations

As was recognized by same of the most reputable physicists of the world such as Galilee and Einstein, the basic laws of physics must inevitably be founded upon invariance principles. Galilean and special relativity stand as historical landmarks that emphasize this message. It's no wonder that the great developments of modern physics (such as those in elementary particle physics) have been keyed upon this concept.

The modern formulation of classical mechanics (see Abraham and Marsden [1]) is based upon "qualitative" or geometric analysis. This is primarily due to the works of Poincare. Poincare showed the value of such geometric analysis …

Magnetic Properties Of [Fe4S4(Sr)4]3- Clusters, G. C. Papaefthymiou, Richard B. Frankel, S. Foner, E. J. Laskowski, R. H. Holm

Physics

No abstract provided.

A Molecular Dynamics Study Of The Stability Of Small Prenucleation Water Clusters, Tze-Shan Chen

Doctoral Dissertations

"The dynamical stability and internal energy distribution of prenucleation water embryos have been studied by the molecular dynamic's method. Water clusters containing either five or twenty molecules were chosen to represent prenucleation embryos of small or intermediate size. A central force potential model of water which allows energy to be absorbed into intramolecular modes so that bond lengths and bond angles could adjust to changes in molecular environments was employed to describe the interaction between all pairs of atoms. The motion of the molecules was followed for extended time periods (of the order of several picoseconds) at each of a …

Amorphous-Damage Depth Distributions And The Amorphization Of Silicon By Ion Bombardment, Joseph Sadowski

Doctoral Dissertations

"Depth distributions of the radiation damage in moderately to heavily ion bombarded silicon was obtained in the following manner: The electron spin resonance signal from an ion bombarded silicon target was measured. This ESR signal was proportional to the amount of amorphous silicon present in the target. A thin oxide of specified thickness was then grown on the surface of the target by anodic oxidation and subsequently stripped off in a HF etch. The depth of the stripped impression below the unoxidized surface was measured using a multibeam interferometer. The amorphous ESR signal was again measured, and the strip / …

Angular Differential Cross Sections For Excitation Of Atomic Hydrogen To Its N=2 Level By Impact Of 15-100 Kev He⁺ Ions, John Eldon Aldag

Doctoral Dissertations

Differential cross sections Ear excitation of atomic hydrogen to its n = 2 level by 15-100 keV He⁺ ions have been determined for cm. angles from Oto 8 m rad. The cross sections were obtained from an analysis of the angular distribution of the scattered ions which had lost an energy corresponding to the excitation of the target to its n= 2 level. The shape of the differential cross section changes rapidly with increasing incident energy. At 15 keV, the cross section falls off by a factor of 5 in 6 m rad. At 100 keV, the cross section …

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

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

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.

Saturated Solar Ponds: Modified Equations And Results Of A Laboratory Experiment, Markus Karl Rothmeyer

Physics & Astronomy ETDs

The diffusion equation for salt gradient solar ponds has been modified to include the Soret effect (a thermal cross-effect due to the temperature gradient). The contribution of the Soret effect to the diffusion flux of salt is shown to be on the order of 4% in the winter and 28% in the summer for the UNM NaCl solar pond. The traditional stability criterion for solar ponds remains practically unchanged by the Soret effect. However, the contribution of non-constant properties (diffusion coefficient, thermal diffusivity and viscosity)--which have been neglected so far--seems to be significant. Saturated solar ponds are described by a …

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 Neutron Total Cross Section Of 208Pb, Lawrence J. Satkowiak

Masters Theses

No abstract provided.

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 …

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 …

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.

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.

Model For Fe2+ Intracenter-Induced Photoconductivity In Inp: Fe, David C. Look

Physics Faculty Publications

We have observed a broad, room-temperature photoconductivity band, with a peak at 0.44 eV, in Fe-doped InP. This band is attributed to an Fe²⁺ intracenter optical excitation, followed by a thermal excitation to the conduction band. We derive a photoconductivity expression which takes into account optical and thermal transitions between impurity ground and excited states, within the band gap, and the conduction band. The parameters yielded by the model include a thermal excitation prefactor of 1×10¹¹ sec^-1, an electron capture cross section of 1×10^-15 cm², a spontaneous recombination coefficient of 1×10⁶ sec …

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.

The Moral Equivalent Of Business As Usual, Harry A. Brown

UMR-DNR Conference on Energy

No abstract provided.

Lasers In Energy Research, Kaare J. Hygaard, Howard L. Brooks, Rafael A. Sierra, Stephen R. Foltyn

UMR-DNR Conference on Energy

No abstract provided.

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

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.

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 …

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.

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.