Digital Commons Network^™

…Y La Junta De Energía Nuclear, Habló, Aldemaro Romero Jr.

Publications and Research

No abstract provided.

Cross Sections For L2,3 Auger Emission In 22- To 300-Kev H+ + Ar Collisions, M. Eugene Rudd

M. Eugene Rudd Publications

Measurements of total and differential L_2,3 Auger cross sections for H⁺ + Ar collisions at 22 - 150 keV are presented. Additional values of these cross sections were calculated from data in earlier investigations by Volz and Rudd and by Crooks and Rudd up to 300 keV. Angular distributions are found to be isotropic. Over most of the energy range the total Auger cross sections are a factor of 2 smaller than predicted by Garcia's binary-encounter calculations.

Unity In The Theory Of Elementary Particles Through Group Theory, Douglas Karl Lemon

Undergraduate Honors Capstone Projects

Science is the process of seeking unity in the diversity of natural phenomenon. The purpose of this paper is to demonstrate that group theory brings unity to the theory of elementary particles. The prime motivations are first, to find a quantitative representation of the Lorentz transformation, and second, to find a quantitative representation of angular momentum. Since both of these have continuous parameters, groups with continuous parameters, particularly Lie groups, are of interest.

The first portion of the paper develops the definition of Lie groups and their associated Lie algebras. The prerequisite definitions of transformations, groups, group representations, and continuous …

The Thermolysis Of Bornyl And Iso-Bornyl Acetates, Allen Reed Jensen

Undergraduate Honors Capstone Projects

Recent investigations in the area of acetate gas phase thermolysis indicate a mechanism which involves a similar transition state despite the acetate used. The reaction preferentially goes through a cis-elimination with the β-hydrogen atoms, proceeding through a six-membered ring transition state.

The purpose of this study is to examine the effect of a strained bicyclic ring system upon the mechanism of acetate thermolysis. Throuqh kinetic studies and product identification of the pyrolyzed products of bornyl and iso-bornyl acetate, an insight into the preferred mechanism can be obtained. A previous study (cited later) indicated that the accepted six-membered cis …

Dispersion Curves For Surface Electromagnetic Waves With Damping, Ralph William Alexander, G. S. Kovener, Robert John Bell

Physics Faculty Research & Creative Works

The Recent Observation of Back bending in the Dispersion Curves of Surface Plasmons on Silver Can Be Explained by Use of Fresnel's Equations. in the Presence of Damping, the Results of Attenuated-Total-Reflection Measurements Can Be Displayed as Dispersion Curves Either with or Without Back bending. the Measurements for Silver with Back Bending Are Expected for Experiments in Which the Frequency is Fixed, and the Propagation Constant (Or Angle of Incidence) is Swept. © 1974 the American Physical Society.

Charge Transfer Between O Ions And O2 Molecules In The Ground State And Singlet Delta Excited State, R. F. Mathis, William R. Snow

Physics Faculty Research & Creative Works

A crossed-beam apparatus has been used to study charge transfer between O- ions and O2 molecules in the ground state and in the metastable, singlet delta, excited state. The energy of the incident ions ranged from 10 to 10000 eV. The cross section for charge transfer between O - and ground state O2 was found to have a maximum of 7.8X10-16 cm2 at about 5 keV. At the lower energies there is good agreement with the previous measurements of Snow et al. and Rutherford and Turner who also used crossed beam techniques. The cross section for charge transfer between O- …

Cryogenic Thin-Film Electron Emitters, Pavel Smejtek, David G. Onn, M. Silver

Physics Faculty Publications and Presentations

Thin‐film electron emitters are described, which operate below 200°K and below a limiting critical applied voltage (νc) in a stable temperature‐independent regime. Current‐voltage characteristics and normal electron energy distributions are presented. Fabrication and operation criteria are outlined. Comparison with temperature‐dependent emitters is made, and possible conduction mechanisms discussed briefly.

Comments On 'Fluctuations In Guiding Center Plasma In Two Dimensions', George Vahala, Linda L. Vahala, David Montgomery, Glenn Joyce

Electrical & Computer Engineering Faculty Publications

It is stated that the principal result of the paper by Taylor and Thompson (see abstr. A14511 of 1973) on autocorrelations in density for the electrostatic guiding center plasma in two dimensions is wrong owing to an incorrect integration. It is further stated that there is no meaningful distinction between an `interaction cutoff' and a `fluctuation cutoff'.

Geophysical Institute Annual Report 1973-74, Geophysical Institute

GI Reports

The 1973-74 Geophysical Institute Annual Report presents an overview of the year’s scientific research achievements across the Institute’s disciplines, alongside operational summaries covering finances, administrative changes, and other key activities.

Cross Sections For Photoionization Of The 6²P-Fine Structure Levels Of Cesium, John Daniel Jones

Doctoral Dissertations

"The cross sections for photoionization of excited cesium from the 6²P_3/2- and 6²P_1/2-fine structure levels have been measured using a triple crossed-beam apparatus. Two photon beams, one for excitation and one for ionization, impinge upon an atomic beam and produce ions at the point of intersection. The relative cross section is determined from a knowledge of the ion count rate and the relative photon flux of the ionization light. The results are normalized to available theoretical calculations and compared with recombination measurements in cesium plasmas. The present cross sections are found to decrease with …

Double Reflection Dips - From Grating Ruled Semiconductors, Le-Fu Teng

Doctoral Dissertations

"The double dips, previously observed by Fischer, Anderson, et al., which appeared in the reflection spectra of grating surfaces on the Te-doped semiconductors GaAs and InSb around the plasmon and phonon frequencies have been measured in more detail. In the plasmon region, several possible explanations of the phenomenon are discussed. A simple equation checked with the rigorous theory is proposed and is shown to fit the data well. In the phonon region, the extra dip is calculated and identified as being caused by surface phonons"--Abstract, page ii.

Surface Electromagnetic Waves With Damping I. Isotropic Media Ii. Anisotropic Media, Gary Shannon Kovener

Doctoral Dissertations

Paper 1: “Surface electromagnetic wave (SEW) 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 k_x becomes infinite as the frequency ω approaches the surface polariton frequency ω_s if ω is considered complex and k_x real. On the other hand, if k_x is considered complex and ω real, the dispersion curves bend back toward smaller k_x as ω approaches ω_s. We have previously demonstrated that both types …

Charge Transfer Between H ˉIons And O₂ Molecules And D ˉIons And O₂ Molecules In The Ground State., Paul Edgar Chaplin

Masters Theses

"This thesis has been prepared in the style utilized by the Physical Review A. Pages 1-17 will be presented for publication in that journal. Appendices I, II, III, and IV have been added for purposes normal to thesis writing"-- Abstract, p. ii

A Computational Method For Determining The Growth Rates Of Saline Water Drops., Robert Alexander Fletcher

Masters Theses

"A phenomenologica1 theory is presented which describes the growth or evaporation of cloud droplets containing dissolved NaCl. The main interest is in the early stages of growth. The Maxwell-Fuchs equation is employed with refinements to account for the high sa1t concentration in small droplets. A computer program is presented that ca1culates the growth time as a function of radius for cloud droplets nucleated with NaCl.

The growth times obtainable from the Maxwe11-Fuchs equation differ significantly from the growth times ca1culated using the refined Maxwell-Fuche equation for ambient relative humidities less than or equal to 100%. Growth times for droplets nucleated …

Erratum: Radiative And Predissociative Lifetimes Of The A ²Σ+ State Of Oh, Richard A. Anderson, R. A. Sutherland

Physics Faculty Research & Creative Works

No abstract provided.

Spectroscopic Determinations Using Resonance Spin-Flip In 12C (P,P1) 12C And 50Ti (P,P1) 50Ti, Lee Robert Baumann

Masters Theses

No abstract provided.

A Direct Measurement Of The Ratio Of The Reaction Cross Sections For Two-Photon And Three-Photon Positron Annihilation In Aluminum And Silver, Robert Maurice Heavenrich

Masters Theses

The probability of annihilation of a positron with its antiparticle, an electron, is spin dependent. Since both particles have spin component one -half, there are two possible relative orientations of their spins they can either be aligned (parallel) in the ³S, triplet, state with total spin component │S_z│= ½ n - ½ n = 1 n or they can be opposite (antiparallel) in the ¹S; singlet, state with│S_z│= ½ n - ½ n = 0. To conserve energy and angular momentum, annihilation from the triplet state must result in the creation of an odd …

Field Radiation Of Spin I Massless Particle, Ralph Alvin Mudgett

Masters Theses

No abstract provided.

A Photographic Study Of The Infrared Oh Airglow, G. C. Loos

Physics & Astronomy ETDs

OH airglow is due to the rotational-vibrational transitions of the hydroxyl radical. Previous efforts to find the airglow's emission height in the atmosphere are discussed. Photography of the infrared airglow with a fast 35mm camera and Eastman Kodak high speed infrared film is described and a method for triangulating emission heights by two station photography is explained. The techniques for reduction of film data to height measurements and velocity measurements are presented. Observations are reported concerning the frequency of occurrence of bright spots and other features on the OH background and the intensity of the airglow as a function of …

Electron Spin Resonance In Argon-Ion-Implanted Silicon, Keh Chang Chu, Weiler R. Hurren, Edward Boyd Hale, John Reigle

Physics Faculty Research & Creative Works

A new paramagnetic center with g = 2.0029 is observed, in both n- and p-type silicon after they are heavily implanted (higher than 1017 ions/cm2) with 150-keV argon ions. © 1973 American Institute of Physics.

Properties Of Microwave Cavities Containing Magnetic Resonant Samples, Kathy A. Rages, Robert E. Sawyer, Edward Boyd Hale

Physics Faculty Research & Creative Works

Properties of TE011 cylindrical, microwave cavities containing cylindrical samples of various radii and dielectric constants are calculated. The properties considered are the resonant frequency, quality factor (Q), relevant magnetic filling factor for spin transitions (ε), and a signal sensitivity factor (Qε) for a lossless sample. Sample sizes range from zero radius to full cavity radius with some experimental data on less than full length samples. The choice of dielectric constants ranges from one to sixteen. The data are presented in dimensionless form since they will be of use to other ESR experimentalists. It is shown that use of large samples …

Self‐Focusing Of Laser Light In The Isotropic Phase Of A Nematic Liquid Crystal, D.V.G.L.N. Rao, S. Jayaraman

Physics Faculty Publications

Self‐focusing of ruby laser light is studied as a function of sample length and temperature in the isotropic phase of nematic liquid‐crystal MBBA. The critical power for self‐focusing, 0.36 kW, observed near the phase transition temperature is a factor of 20 times less than that for CS₂. The corresponding nonlinear index 4.4 × 10⁻¹⁰ esu is the largest value known so far for any material.

Dissociative Attachment From The O2 (A1 Δ G) State, P.D. Burrow

Paul Burrow Publications

The dissociative attachment cross section for production of O^- by electron impact on the metastable O₂ (a¹ Δ _g) state is studied. The cross section is found to be 4.6 ± 1.3 × 10^-18 cm² at its maximum. From the measured energy dependence, we infer that the dissociative attachment process takes place through the O^2̅ (² П_u) state as in the case of O^- production from the O₂ ground state. The information thus obtained is used to estimate the portion of the cross section for excitation of the …

Raman Spectrum Of Gadolinium Molybdate Above And Below The Ferroelectric Transition, Frank Ullman, B. J. Holden, B. N. Ganguly, John R. Hardy

John R. Hardy Papers

90 °-scattered Raman spectra of single-domain gadolinium molybdate have been obtained at room temperature and above the 159 °C ferroelectric transition on several crystal orientations. Lines in the 0-200-cm^-1 range can all be associated with Raman-active phonons and are identified by symmetry considerations, scattering-efficiency calculations, and comparison of spectra for different crystal orientations. Lines in the 200-1000-cm^-1 range can be identified with coupled vibrations of tetrahedral molybdate ions. Spectra for frequencies above 1,000 cm^-1 originate from impurity flourescence. The effect of the presence of multiple domains on the spectra was determined; the observed differences between single-domain and …

Orbital Ground State Inversion In [Fe(H2O)6](Clo4)2, W. M. Reiff, Richard B. Frankel, C. R. Abeledo

Physics

Mössbauer spectroscopy in external magnetic fields has been used to measure the signs of the principal components of the electric field gradient V_zz in the two forms of [Fe(H₂O)₆)(Cl0₄)₂. The signs are V_zznegative for low temperature form (A) with quadrupole splitting ΔE_A = 3.4 mm/sec, and V_zz positive for high temperature form (B) with ΔE_B = 1.4 mm/sec. This implies a trigonally distorted ligand field and the transition (A) → (B) corresponds to compression → elongation with respect to the trigonal axis.

Hyperfine Interactions In The Intramolecular Antiferromagnet (Fe Salen C1)2, R. Lechan, C. Nicolini, C. R. Abeledo, Richard B. Frankel

Physics

Magnetic hyperfine interactions in (Fe salen C1)₂ have been studied using the Mössbauer effect in external magnetic fields up to 80 kOe and for 4.2 ≤ T ≤ 80 °K. The low‐temperature results are adequately described by a simple intramolecular exchange model with J = 7.0 cm⁻¹ and a hyperfine interaction constant of −180 kOe per unit spin. At higher temperature the effective field approximation breaks down. Data for (Fe salen)₂O are also briefly reported.

Magnetic Interactions And High-Field Magnetization In Dilute Magnetic Alloys , J.M. Franz, David J. Sellmyer

David Sellmyer Publications

Magnetic interactions have been investigated in Cu(Mn) and Cu(Fe) alloys with concentrations ranging from several hundred to several thousand ppm. In each system two sets of alloys were prepared in different ways to test for sensitivity to structrual modifications. In the Cu(Mn) alloys there was very little difference in magnetic properties of the two sets of alloys which is consistent with the expectation that the Cu(Mn) alloys form good random solid solutions. The magnetic properties were compared with the recent mean-random-field theory of Klein in the low-temperature limit. It was found that the theory is able to explain the concentration …

Lattice Dynamics Of A Rigid-Ion Model For Gadolinium Molybdate, L. L. Boyer, John R. Hardy

John R. Hardy Papers

Results of lattice-dynamical calculations are presented which support the view that the ferroelectric phase transition in gadolinium molybdate (GMO) arises from the softening and ultimate instability of a doubly degenerate zone-edge mode of the high-temperature paraelectric phase. We have used a rigid-ion model in which the short-range force constants are obtained from a detailed knowledge of the crystal structure together with the conditions imposed by the requirement that the crystal must be in static equilibrium under the combined influence of both Coulomb and short-range forces. Our results show that this type of approach is very useful when one is dealing …

Orbital Ground State Reversal In The High‐Spin Complex Fe(Ii) (N, N′‐Dicyclohexylthiourea)6(Clo4)2, R. Latorre, C. R. Abeledo, Richard B. Frankel, J. A. Costamagna, W. M. Reiff, E. Frank

Physics

Mössbauer spectroscopy of iron (II)(N, N′‐Dicyclohexylthiourea)₆ (ClO₄)₂ shows the existence of two isomers. At low temperatures (T < 200°K) a form A with quadrupole splitting ΔE = 3.31 mm∕sec is stable. At and above room temperature a form B with ΔE = 1.32 mm∕sec is stable. For 200 °K < T < 300°K both forms are observed with the B∕A ratio increasing with increasing temperature. The values of ΔE are typical of Fe²⁺ with an orbital singlet and an orbital doublet ground state for A and B, respectively. The isomer shift and magnetic susceptibility results indicate that both …

High Magnetic Field Behavior Of Iron Impurities In Chromium, Richard B. Frankel, N. A. Blum

Physics

Mössbauer measurements in ⁵⁷Fe in dilute FeCr alloys in external magnetic fields up to 140 kOe are presented. The magnetic hyperfine interactions are compared with results obtained by Herbert, Clark and Wilson and are discussed in terms of a model due to Housley and Dash.