Digital Commons Network^™

Valence-Band Information From The Auger Kvv Spectrum Of Graphite, M. A. Smith, L. L. Levenson

Physics Faculty Research & Creative Works

The Auger KVV and x-ray photoelectron valence-band spectra of atomically clean, well-ordered graphite are measured. After background subtraction is performed and a deconvolution technique is used to remove energy-dependent features from the Auger data, the transition density function is calculated for the graphite valence band. A comparison is made with other experimental work and with a density-of-states calculation. It is found that the transition density closely resembles the density of states if localized hole effects are considered. © 1977 The American Physical Society.

Energy Dependence Of Amorphizing Implant Dose In Silicon, John R. Dennis, Edward Boyd Hale

Physics Faculty Research & Creative Works

The radiation-induced transformation from crystalline to amorphous silicon was studied using ion implantation. The ion energy was varied from 20 to 180 keV for Li+, N+, Ne+, Ar+, and Kr +. The energy dependence of the critical amorphizing dose was determined by electron spin resonance. Comparison of the data with theoretical calculations of the energy density deposited into atomic processes showed good agreement. This energy-dependent agreement gave evidence that energy density is important to the transformation at both low and high implantation temperatures.

Synthetic Analogs Of The Active Sites Of Oxidized And Reduced Rubredoxin, Richard B. Frankel, G. C. Papaefthymiou, R. W. Lane, R. H. Holm

Physics

The bischelate monoanion [Fe((SCH₂)₂C₆H₄)₂]^1- contains an unconstrained, near-tetrahedral Fe(III)-S₄ coordination unit (similar to the Fe-S₄ coordinationunit occurring in rubredoxin proteins) and exhibits the Fe(III)/Fe(II) redox couple. Mossbauer parameters at 77 K are isomer shift δ = 0.13 mm/s (relative to iron metal) and electric quadrupole splitting ΔE_Q = 0.57 mm/s. Application of an external magnetic field parallel to the direction of observation at 4.2 K induces a saturation magnetic hyperfine field of - 380 kOe. Upon reduction to the dianion [Fe((SCH₂)₂C …

Model Fe(Iii) Porphyrin Systems: Axial Ligation In Oxidized Cytochrome P-450.S, G. C. Papaefthymiou, Richard B. Frankel, S. Foner, S. C. Tang, S. Koch, R. H. Holm

Physics

In an effort to develop useful experimental criteria to distinguish among the viable axial ligation possibilities of O, N, and S coordination in oxidized cytochrome P-450. S (substrate-bound, high-spin), syntheticmodel compounds with O-(Fe(PPIXDME) (OEt) and Fe(PPIXDME) (OC₆H₄NO₂)) and S-(Fe(PPIXDME) (S₆H₄NO₂) and Fe(OEP) (SPh)) donor axial ligands were prepared and studied by Mössbauer spectroscopy. Ferric hemoglobin and myoglobin were used as model compounds with N-axial coordination. The isomer shifts (δ) and quadrupole splittings (ΔE_Q) observed are typical of high-spin Fe(III) porphyrins and are comparable with results …

Excitation Of The N=2 State Of Atomic Hydrogen By Electron Impact In The Distorted-Wave Approximation, Ralph V. Calhoun, Don H. Madison, W. Neil Shelton

Physics Faculty Research & Creative Works

The differential cross sections for excitation of the n=2 state of atomic hydrogen by the impact of electrons with energies of 54, 100, 136, and 200 eV are calculated in the distorted-wave approximation with exchange included. Cross sections for excitation of the 2s_1/2, 2p_1/2, and 2p_3/2 states are calculated and summed to give the n=2 differential cross sections. The results of this calculation are compared with previous theoretical calculations and with recent absolute experimental data.

Calculated Temperature Of Grid Lateral Wires In Microwave Power Triodes, Jewell Tucker

Masters Theses & Specialist Projects

In microwave power triodes the grid drive power causes grid lateral wire heating. This development calculates the temperature of the wire as a function of the drive power, physical dimensions and characteristics of the wire material, for the following boundary conditions:

I. Constant grid drive, grid lateral wire of infinite length not connected to a heat sink.

II. Same as I except the wire is of finite length brazed to a grid frame.

III. The grid excitation in the form of pulses, and the grid lateral wire of finite length brazed to a grid frame.

the equations were verified experimentally …

18th Annual Rocky Mountain Spectroscopy Conference

Rocky Mountain Conference on Magnetic Resonance

Final program and abstracts from the 18th 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 2-3, 1976.

Cross Sections For Excitation Of Atomic Hydrogen To The N=2, 3, And 4 States By 15-200-Kev Protons, John T. Park, John E. Aldag, Jacob M. George, Jerry Peacher

Physics Faculty Research & Creative Works

Cross sections for the processes H⁺+H(1 s)H⁺+H*(n = 2, 3, 4) have been extracted from the energy-loss spectra of 15- to 200-keV protons by using a spectrum-fitting technique. Absolute cross sections have been obtained by normalization of the spectra to the theoretical cross section through the use of the Born approximation at 200 keV. The cross-section curves are very similar in shape with maxima at 60 keV. The results have been compared with available theoretical calculations. The n = 2 and n = 3 cross-section measurements are in very good agreement in curve shape with Glauber-approximation …

Electrical Conductivity Of Thin Lecithin-Cholesterol Membranes Due To 2,4-D, 2,4-Db, 2,4,5-T And 2,4-Dcp, Malkanthi Paulis

Dissertations and Theses

The effect of the following pesticides on DC electrical conductivity of lecithin-cholesterol membranes has been studied: endothall, paraquat, diquat, 2,4-D, 2,4-DB, 2,4,5-T, 2,4-DCP. It has been found that the ions of endothall, paraquat and diquat are essentially membrane impermeable and that they do not bind to the membrane surface. In contrast, 2,4-D, 2,4-DB, 2,4,5-T and 2,4-DCP induce electrical conductivity in lecithincholesterol membranes and in addition they also cause an increase in the nonactin-K⁺ membrane conductivity.

The compounds 2,4-D, 2,4-DB, 2,4,5-T and 2,4-DCP basically behave as class II uncouplers. The kinetic scheme of charge transfer across the membrane, based on …

Systematic Evaluation Of Cellular Radiosensitivity Parameters, R. A. Roth, S. C. Sharma, Robert Katz

Robert Katz Publications

Cellular radiosensitivity parameters of the track structure theory of Katz and co-workers are evaluated from a sum of squares minimizing computer program for nonlinear models. Based on these observations, suggestions are presented for efficient experiment design for the determination of these parameters from track-segment bombardments of high LET radiations.

Comparison Of Experimental And Theoretical Electron Ejection Cross Sections In Helium By Proton Impact From 5 To 100 Kev, M. Eugene Rudd, Don H. Madison

Physics Faculty Research & Creative Works

Absolute values of doubly differential cross sections are obtained for electron production in helium by 5- to 100-keV proton impact. The measured values along with earlier data at higher energies are compared with theoretical plane-wave Born-approximation functions obtained from a Hartree-Fock potential. Not only is good agreement obtained at high impact energies (above 300 keV), but fairly good agreement is found at low energies (below about 20 keV). For electrons ejected in the backward hemisphere, unexpectedly poor agreement is noted at intermediate energies where the measured cross sections dip to 50% of the calculated values in some cases. Singly differential …

Photoinization Cross Sections For Atomic Chlorine Using An Open-Shell Random-Phase Approximation, Anthony F. Starace, Lloyd Armstrong Jr.

Anthony F. Starace Publications

The use of the random-phase approximation with exchange (RPAE) for calculating partial and total photoionization cross sections and photoelectron angular distributions for open-shell atoms is examined for atomic chlorine. Whereas the RPAE corrections in argon (Z=18) are large, we find those in chlorine (Z=17) to be much smaller due to geometric factors. Hartree-Fock calculations with and without core relaxation are also presented. Sizable deviations from the close-coupling results of Conneely are found.

Debye–Hückel Theory For Rigid‐Dipole Fluids, John D. Ramshaw

Physics Faculty Publications and Presentations

The dipolar analog of classical linearized Debye–Hückel theory is formulated for a finite fluid system of arbitrary shape composed of rigid polar molecules. In contrast to the ionic case, the dipolar Debye–Hückel (DDH) theory is nonunique due to an inherent arbitrariness in the choice of a local field E*. This nonuniqueness is expressed in terms of a parameter ϑ related to the ellipticity of the spheroidal cavity used to define E*. The theory then leads to an expression for the direct correlation function c (ϑ) as a function of ϑ. Only the short‐range part of c (ϑ) depends upon ϑ; …

Hall-Effect Measurements In Cd-Implanted Gaas, B. K. Shin, David C. Look, Y. S. Park, J. E. Ehret

Physics Faculty Publications

Cadmium ions were implanted in GaAs crystals at 135 keV to doses ranging from 10¹² to 10¹⁶ ion/cm² at room temperature. Sheet‐resistivity and Hall‐effect measurements were carried out as a function of temperature, 4.2–300°K, after annealings at 700, 800, or 900°C in an Ar ambient. The sample surfaces were protected with pyrolytically deposited Si₃N₄. Significant p‐type conduction was observed when samples with doses ≳10¹³cm⁻² were annealed at ≳700°C. For doses below 10¹⁴ cm⁻² nearly complete electrical activity was attained after an 800–900°C anneal. The Cd profiles were …

"Nuclear Power: Its Role In Our Future", Betsy Macinness, Dave Ferg, Rudi Nussbaum, Tom Davis, Sandra Kiefer

Special Collections: Oregon Public Speakers

No abstract provided.

Four-Color And Hβ Photometry Of The Galactic Cluster Ngc 6633, Edward G. Schmidt

Edward Schmidt Publications

Photometric measurements of stars in the intermediate-age galactic cluster NGC 6633 are presented. From these data the color excess is found to vary slightly across the cluster with an average of E_{b – y} = 0^m.124. The distance modulus is found to be 7^m.711 and the turnoff occurs at about (b – y)₀ = 0^m.l. The cluster is slightly metal poor.

Comparison Of Experimental And Theoretical Electron Ejection Cross Sections In Helium By Proton Impact From 5 To 100 Kev, M. Eugene Rudd, D. H. Madison

M. Eugene Rudd Publications

Absolute values of doubly differential cross sections are obtained for electron production in helium by 5- to 100-keV proton impact. The measured values along with earlier data at higher energies are compared with theoretical plane-wave Born-approximation functions obtained from a Hartree-Fock potential. Not only is good agreement obtained at high impact energies (above 300 keV), but fairly good agreement is found at low energies (below about 20 keV). For electrons ejected in the backward hemisphere, unexpectedly poor agreement is noted at intermediate energies where the measured cross sections dip to 50% of the calculated values in some cases. Singly differential …

Impurity-Concentration Profile For An Exponentially Decaying Diffusion Coefficient In Irradiation Enhanced Diffusion, J Kowall, David Peak, J W. Corbett

All Physics Faculty Publications

The diffusion equation is solved for a semi-infinite region in the case of irradiation-enhanced diffusion produced by a diffusion coefficient falling off exponentially in the medium. Near the surface the concentration profile due to enhanced diffusion has a larger concentration than the profile due to thermal diffusion; conversely far from the surface the enhanced-diffusion profile has a lower concentration than that due to thermal diffusion. Thus, this type of enhanced diffusion results in a more abruptly changing profile than does thermal diffusion.

Competitive Effect On The Rate Of The Diffusion-Controlled Reaction A+B→C, David Peak, K Pearlman, P J. Wantuck

All Physics Faculty Publications

None available; appears in letters section.

Radiative Lifetimes Of Some Group Ii Ions By The Hanle Effect In A Fast-Flowing Helium Afterglow, F. H.K. Rambow, Laird D. Schearer

Physics Faculty Research & Creative Works

Radiative lifetimes of the first P322 state of Mgu, Cau, Znu, Sru, Cdu, and Bau are reported as measured by the Hanle effect in a fast-flowing helium afterglow. They are, respectively, 3.65(0.12), 6.61(0.30), 2.4(0.3), 6.64(0.10), 2.86(0.25), 6.78(0.40) in units of 10-9 sec. The ions in the afterglow are created by Penning ionization of the neutral metal atoms, thus providing a steady-state, field-free region for observation. Comparisons are made with measurements by other methods, and discrepancies are discussed. © 1976 The American Physical Society.

Nuclear Spin Relaxation By Intramolecular Interactions In Gases Of Homonuclear Diatomic Molecules, Myer Bloom, Peter A. Beckmann, B C. Sanctuary

Physics Faculty Research and Scholarship

The differential equations which describe the relaxation of macroscopic observables associated with nuclear spins in homonuclear diatomic molecules are derived using an expansion of the nuclear spin density matrix in terms of irreducible tensors. It is shown, using an intramolecular quadrupole mechanism, that the only difference between nuclear spin relaxation of the ortho- and para-species arises from the rotational states being restricted to odd and even values. This difference is vanishingly small at high temperatures so that the relaxation equations for nuclear magnetization become identical for both species. A previous paper predicting a difference even at high temperatures is …

Proton Spin Relaxation In Dilute Methane Gas: A Symmetrized Theory And Its Experimental Verification, Peter A. Beckmann, M. Bloom, I. Ozier

Physics Faculty Research and Scholarship

Nuclear spin relaxation in low density methane gas is investigated theoretically and experimentally. A theory is developed in which full account is taken of the tetrahedral symmetry of the molecule. For a nuclear Larmor frequency of 30 MHz, the time evolution of the nonequilibrium magnetization is measured as a function of density between approximately 0.005 and 17 amagats at temperatures of 110, 150, and 295 K. In all cases, exponential relaxation is observed. By using the theory in conjunction with the known spin rotation constants and rotational energy levels of CH₄, the measured values of the relaxation rate …

Radiative Lifetimes And Alignment Depolarization Cross Sections For Ybi And Ii By The Hanle Effect In A Flowing Helium System, F. H.K. Rambow, Laird D. Schearer

Physics Faculty Research & Creative Works

The radiative lifetimes of the 17992-,25068-,28857-, 37414-, 40564-, and 44017-cm-1 neutral levels and the 30392-cm-1 ion level of Yb have been measured by the Hanle method in a fast-flowing He system. The lifetimes (in units of 10-9 sec) were found to be 820(20), 5.12(0.12), 14.4(0.4), 77.4(6.0), 9.32(0.6), 39.1(3.5), and 5.8(0.6), respectively. In a flowing system with He as a buffer gas the alignment depolarization cross sections with Yb were obtained and are reported here for the first time. They are (in units of 10-15 cm2) 5.0(1.0), 5.9(1.0), 5.9(1.2), 17.9(2.0), 28.2(3.0), 5.16(4.0), and 7.2(2.5), respectively. © 1976 The American Physical Society.

Surface Electromagnetic Waves With Damping. I. Isotropic Media, G. S. Kovener, Ralph William Alexander, Robert John Bell

Physics Faculty Research & Creative Works

Surface-Electromagnetic-Wave Dispersion Curves Are Usually Calculated using a Simple Equation Derived from Maxwell's Equations and Boundary Conditions. When Complex Dielectric Functions Are Used for the Two Media, the Component of the Propagation Vector Along the Surface, Kx, Becomes Infinite as the Frequency Approaches the Surface Polariton Frequency Ωs If Ω is Considered Complex and Kx is Real. on the Other Hand, If Kx is Considered Complex and Ω Real, the Dispersion Curves Bend Back Toward Smaller Kx as Ω Approaches Ωs. We Have Previously Demonstrated that Both Types of Behavior Can Be Obtained from Attenuated-Total-Reflection Measurements of Silver. We Now …

Model System Studies Of Axial Ligation In The Oxidized Reaction States Of Cytochrome P-450 Enzymes, R. H. Holm, S. C. Tang, S. Koch, G. C. Papaethymiou, S. Foner, R. B. Frankel, J. A. Ibers

Physics

No abstract provided.

H I In Early-Type Galaxies. Ii. Mass Loss And Galactic Winds, S. M. Faber, J. S. Gallagher

Department of Physics and Astronomy: Faculty Publications

Implications of observed upper limits to the neutral hydrogen content of E and SO galaxies from Paper I are discussed. If gas shed by dying stars is completely retained by these galaxies and exists as H I, these upper limits will be exceeded in only 10⁹ yr for E's and SO's and in only 2 x 10⁸ yr for NGC 4472. Evidently, gas either is hidden in some undetectable form or is removed from the interstellar medium completely.

Video Tape : An Old-New Instructional Aid In The Physics Laboratory, Fanny Mercedes Torres Holguin

University of the Pacific Theses and Dissertations

My objective is to use the video-tape as another medium -- along with overhead projector, textbooks, guides of apprenticeship, pictures, lab equipment and suggestions from the programs and new trends in physics teaching -- being used to supplement our efforts in trying to reach more and more of our students The use of audiovisual media, and generally speaking the use of technology in education, can be constructive or destructive, can e very powerful in developing "human beings" or "robots", can increase the rate of apprenticeship, or can produce an educational catastrophe. However, it will heavily depend on the the professor, …

The Magnification Factor For Sodium Chloride Liesegang Circles Established With An Aerosol Centrifuge, O. Preining, Josef Podzimek, P. Yue

Physics Faculty Research & Creative Works

Sodium chloride particles deposited on a gelatin film containing silver nitrate form in a humid environment clearly visible dark brown reaction spots (Liesegang circles) after development in u.v.-light. The size of these reaction spots depends on the mass of NaCl in the particles. To establish the spot size vs particle size relation, particles produced by nebulising NaCl-solutions and sea water were sampled in an aerosol centrifuge. The location of deposition yields the aerodynamic diameter of the particle, and the spot size is measured microscopically. In this way the spot size vs aerodynamic diameter relation is established experimentally in the so …

Ultraviolet Excitation Thermoluminescence Of Lead-Manganese Calcium Carbonate, Dennis Schrope

Masters Theses & Specialist Projects

Calcium carbonate with impurities of lead and manganese have produced measurable thermoluminescence (TL) when excited by ultraviolet (uv) radiation. In this investigation the lead impurities comprise the majority of trapping centers stimulated by uv irradiation. In addition, centers associated with the CO₃groups have been found to be capable of absorbing uv and ultimately producing TL. The 2537 Å mercury line is primarily responsible for stimulating these centers, and the response was found to be linear to 0.6734 joules/cm².

The thernoluminescence response was discovered to be dependent on the concentrations of lead and manganese. However, for a …

Saturation Effects In A Tunable Coherent Near-Infrared Source, Israel L. Tyler, R. (Ralph) W. Alexander, R. (Robert) J. (John) Bell

Physics Faculty Research & Creative Works

A Saturation Effect in a Tunable Infrared Source Utilizing Four-Wave Parametric Conversion in Potassium Vapor is Reported and is Shown to Be the Result of Parasitic Oscillations. a Hundredfold Increase over Previously Attained Power Levels Has Been Affected Via Elimination of These Oscillations.