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A Survey Of The Methods For Producing Extremely Low Temperatures, Patricia M. Boise Jan 1969

A Survey Of The Methods For Producing Extremely Low Temperatures, Patricia M. Boise

Departmental Honors & Graduate Capstone Projects

A Survey of the Methods for Producing Extremely Low Temperatures

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Vapor Phase Clustering Model For Water, Richard W. Bolander Jan 1969

Vapor Phase Clustering Model For Water, Richard W. Bolander

Doctoral Dissertations

"Although nucleation phenomena are among the most widespread of all naturally occurring phenomena, even the simplest of nucleation processes, homogeneous nucleation, is poorly understood, particularly the homogeneous nucleation of liquid droplets from water vapor. Homogeneous nucleation involves only molecules of a single substance and does not include the complicating effects due to a substrate or piece of foreign matter. The semiphenomenological liquid drop theories developed nearly three decades ago differ in relatively minor details, with the crucial element of the theory being the derivation of the free energy of formation of the clusters. The clusters are viewed as well-defined incompressible …

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A.C. Hall Effect Measurements On Very High Resistivity Materials Exhibiting Electrode Polarization, James Dale Boyd Jan 1969

A.C. Hall Effect Measurements On Very High Resistivity Materials Exhibiting Electrode Polarization, James Dale Boyd

Doctoral Dissertations

"A variable frequency, a.c. Hall effect measurement technique has been designed for mobility studies in very high resistivity (>10⁹ ohm·cm) materials exhibiting electrode space charge polarization effects. It incorporates a neutralized input capacitance preamplifier detector which reduces the total input shunting capacitance, including the sample interelectrode capacitances, to a very low, definable value (<0.1 pf) and thereby provides very high and well defined a.c. detector input impedances (4 x 10⁹ and 7 x 10⁹ ohms at 600 and 200 Hz, respectively). Lumped parameter equivalent circuits have been defined to approximate the electrical behavior of sample materials in the measurement configuration. These equivalent circuits, together with independent measurements of the detector input and sample impedances, allow one to correct the detected Hall voltage and obtain the true value from which mobility data may be derived. The validity of these circuits has been established by independent a.c. and d.c. measurements on photoconductive CdS (dark resistivity >10¹⁰ ohm·cm) which exhibited maximum differences of less than 4%. The existing literature has been critically reviewed and the measurement criteria established by this study have been applied to resolve differences in reported data and to suggest improvements in the resolution of previously employed experimental …

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A Study Of The Energy Loss Spectra Induced By Impact Of 23-125 Kev Protons On Helium Atoms, Franklin Dean Schowengerdt Jan 1969

A Study Of The Energy Loss Spectra Induced By Impact Of 23-125 Kev Protons On Helium Atoms, Franklin Dean Schowengerdt

Doctoral Dissertations

"Results of a study of the inelastic energy loss spectra induced by the impact of protons on gaseous helium at energies of 25 to 125 keV are reported. The spectra were obtained by sending an accelerated beam of protons through a chamber containing the helium target gas, mass-analyzing the forward-scattered beam, then decelerating the beam to a low, well-defined energy for energy analysis and detection. The accelerating potential was varied to produce the spectra. An energy resolution of 2 eV was obtained. Apparent differential cross sections and absolute total cross sections were obtained from the spectra. Total cross sections for …

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Low-Lying Levels In Some Spherical And Rotational Nuclides By Coulomb Excitation And Radiative Capture Of Thermal Neutrons, Donald Allan Mcclure Jan 1969

Low-Lying Levels In Some Spherical And Rotational Nuclides By Coulomb Excitation And Radiative Capture Of Thermal Neutrons, Donald Allan Mcclure

Doctoral Dissertations

"The work presented in this dissertation was performed in order to obtain additional information on the level schemes and decay properties of several nuclei in an attempt to explain the observations in terms of an applicable nuclear model. Various nuclear models are discussed in Section II. A general review from the classical point of view of the Coulomb excitation reaction is discussed in Section III and the thermal-neutron-capture reaction is outlined in Section IV. The experimental equipment and procedure is discussed in Section V in which the ramper method of energy determination is outlined. This method allows the measurement of …

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MöSsbauer Effect Studies Of Ferroelectric Phase Transitions In The Pbzro₃ - Pbtio₃ - Bifeo₃ Ternary System, James P. Canner Jan 1969

MöSsbauer Effect Studies Of Ferroelectric Phase Transitions In The Pbzro₃ - Pbtio₃ - Bifeo₃ Ternary System, James P. Canner

Doctoral Dissertations

"The Mössbauer Effect was used to measure the phase transitions in the following ferroelectric compounds: 95% PbZ4₀.₈Ti₀.₂ - 5% BiFeO₃ [and] 95% PbZ4₀.₇Ti₀.₃ - 5% BiFeO₃ and in the antiferroelectric compound: 95% PbZrO₃ - 5% BiFeO₃. The parameters obtained were the area under the resonance peak, the isomer shift, and the electric quadrupole splitting, all as a function of temperature. The ionicity, electric field gradient, and Debye temperature were determined for room temperature. The data are discussed in terms of the lattice vibration model of ferroelectrics and antiferroelectrics, and the structural phase transitions as recently defined for these compounds. The …

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Radiative Lifetime Of The B¹Σ⁺ And B³Σ⁺ States Of Carbon Monoxide, John Robert Rogers Jan 1969

Radiative Lifetime Of The B¹Σ⁺ And B³Σ⁺ States Of Carbon Monoxide, John Robert Rogers

Doctoral Dissertations

"The radiative lifetimes of the B¹Σ⁺ and b³Σ⁺ excited states of carbon monoxide were measured at six different pressures: 10, 25, 50, 75, 100, and 125 microns of Hg. The lifetimes were obtained by observation of the radiative decay of the (0,0), (0,1), (0,2), and (1,1) bands of the Angstrom system and the radiative decay of the (0,1), (0,2), (0,3), and (0,4) bands of the Third Positive system. No pressure dependence of the lifetimes was observed for either system. The average lifetime of the v' = 0 vibrational level of the B¹Σ⁺ state was found to be 24.4 x 10⁻⁹ …

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The Statistics Of Finite, One Dimensional Lattice Fluids, John Roger Glaese Jan 1969

The Statistics Of Finite, One Dimensional Lattice Fluids, John Roger Glaese

Doctoral Dissertations

"A one dimensional lattice fluid in which particles are allowed to assume only discrete positions is proposed. Particles are free to move from one lattice site to another interacting through a variety of potentials, including the Lennard-Jones type. The model allows the partition function to be evaluated as a discrete sum over the allowable configurations. Both the canonical ensemble and grand ensemble are treated by computer and a third, the pressure ensemble, is considered and shown to be useful in the theoretical treatment of lattice systems. The thermodynamic behavior of various systems is investigated in both the canonical and grand …

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Infrared Cooling Near Atmospheric Temperature Inversions And Absorber Concentration Variations, Joey Keith Tuttle Jan 1969

Infrared Cooling Near Atmospheric Temperature Inversions And Absorber Concentration Variations, Joey Keith Tuttle

Masters Theses

"Cooling due to infrared radiation near temperature inversions is investigated. Temperature inversions tend to hold pollution below the inversion level. The pollution itself may contribute to the stability of the inversion by selectively cooling certain portions of the atmosphere. A method is developed for evaluating infrared cooling rates at discreet points in the atmosphere. Several sample calculations are given to demonstrate the effects of variations of absorber concentration and lapse rate"--Abstract, page i.

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An Experimental Comparison Of Various Nuclei Counters, Joel William Mansell Jan 1969

An Experimental Comparison Of Various Nuclei Counters, Joel William Mansell

Masters Theses

"A series of simultaneous nuclei concentration measurements, with four different nuclei counters, have been made. these counters were a Pollak and a Gardner counter supplied by Mr. Paul Allee of the Environmental Science Services Administration, Boulder, Colorado, and a Pollak and a G.E. counter supplied; by Mr. Norman White of the National Center for Air Pollution Control, Cincinnati, Ohio. In the absence of any knowledge of the absolute concentrations in the samples, the data for each of the individual counters have been compared to the averages computed from all four counters. The results of these comparisons indicate the following: (1) …

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A Low Frequency Phase Shift Method, Ronnie Carroll Mcmillan Jan 1969

A Low Frequency Phase Shift Method, Ronnie Carroll Mcmillan

Masters Theses

"The phase shift method of measuring atomic lifetimes is particularly useful because it allows us to make measurements in the steady state mode instead of in the transient mode. High frequency phase shift techniques cause many problems. The equipment, which was designed and built to make low frequency phase shift techniques possible, is shown schematically and discussed. The new experimental techniques employed in our apparatus are a phase multiplier and a unique method of using a photomultiplier as a mixer. In the photomultiplier the final dynode is used as the grid of a triode. The next to the last dynode …

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Mixed Magnetic Systems: A Model With Application To (1-X)Cdcr2s4 · Xcdcr2se4, Harry A. Brown Jan 1969

Mixed Magnetic Systems: A Model With Application To (1-X)Cdcr2s4 · Xcdcr2se4, Harry A. Brown

Physics Faculty Research & Creative Works

The Curie temperatures and asymptotic Curie temperatures are calculated for mixed magnetic systems by a semi-classical Bethe-Peierls-Weiss cluster approach. The systems are typified by (1-x) CdCr2Se4 · xCdCr2Se4 in which the substitution changes the anions but not the magnetic cations. It is found that next-nearest-neighbor interactions are needed to match the data but that, with them, excellent agreement can be obtained for a reasonably unique choice of the exchange integrals. © 1969.

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Semiempirical Determination Of The Hydrogen Bond Energy For Water Clusters In The Vapor Phase. I. General Theory And Application To The Dimer, Richard W. Bolandee, James L. Kassner, Joseph T. Zung Jan 1969

Semiempirical Determination Of The Hydrogen Bond Energy For Water Clusters In The Vapor Phase. I. General Theory And Application To The Dimer, Richard W. Bolandee, James L. Kassner, Joseph T. Zung

Physics Faculty Research & Creative Works

A simple semiempirical method is given for determining the hydrogen bond energy for water clusters in the vapor phase. This method is based on a general statistical-mechanical theory of clustering. The partition function for a system of clusters is used to determine the equilibrium distribution of clusters. In conjunction with available thermodynamic and spectroscopic data, the cluster equilibrium constants can be used to calculate the cluster potential energy and the hydrogen bond energy. Results for the water dimer agree quite well with other reported values obtained either by quantum-mechanical calculations or approximate thermodynamic estimates. A correct temperature dependence of the …

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Longitudinal Optical Phonon-Plasmon Coupling In Ionic Semiconductors, Thomas Joseph Mcmahon Jan 1969

Longitudinal Optical Phonon-Plasmon Coupling In Ionic Semiconductors, Thomas Joseph Mcmahon

Doctoral Dissertations

"The coupling of free carriers and lattice vibrational modes is studied in CdS and InSb by room temperature far infrared reflectance measurements. When the free carrier concentration is such that the plasma frequency is at or near the longitudinal optical mode frequency it is shown that while the transverse modes remain fixed, the longitudinal modes mix with the plasma mode and are shifted in a manner similar to that described by Varga in 1965. Using the dielectric function for the coupled system permits the determination of electron effective masses by reflectance measurements with lattice effects excluded. This method allows one …

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Ionic Transport In Potassium Chloride, Robert Fuller, Charles L. Marquardt, Michael H. Reilly, John C. Wells Jr. Dec 1968

Ionic Transport In Potassium Chloride, Robert Fuller, Charles L. Marquardt, Michael H. Reilly, John C. Wells Jr.

Robert G. Fuller Publications

The electrical conductivity and chlorine ion diffusion in KC1 and KCl:SrC12 single crystals have been analyzed by least-squares methods, using as a model a perfect crystal perturbed by five defects: isolated anion vacancies, isolated cation vacancies, divalent cation impurities, divalent cation-impurity-cation-vacancy complexes, and vacancy pairs. The transport equations were derived from this five-defect model using a simple theory for noninteracting particles, except for the nearest-neighbor binding to form complexes and vacancy pairs, and using the same theory including long-range Coulomb interactions between the isolated defects. This latter theory yielded the better description of the experimental results. However, the analyses …

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Rotational Excitation Of Polar Molecules By Electrons, Marvin H. Mittleman, Jerry Peacher, Balazs F. Rozsnyai Dec 1968

Rotational Excitation Of Polar Molecules By Electrons, Marvin H. Mittleman, Jerry Peacher, Balazs F. Rozsnyai

Physics Faculty Research & Creative Works

Rotational excitation of polar molecules is calculated in the approximation that the electron transit time is short compared with rotational periods with the result of an E-1 behavior of the cross section. Diffusion cross sections are calculated for Δl=0,1,2. Significant corrections to the Born approximation are obtained for large dipole moments. The range (in energy) of applicability of the result is discussed in terms of the energy dependence of the corrections, and a novel energy dependence of these corrections is encountered and explained.

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Energy Deposition By Electron Beams And Δ Rays, E. J. Kobetich, Robert Katz Dec 1968

Energy Deposition By Electron Beams And Δ Rays, E. J. Kobetich, Robert Katz

Robert Katz Publications

The product of two empirical relations, for the practical range and the transmission probability of normally incident electrons through plane sheets of matter, may be differentiated to yield a simple formulation of the energy deposition by electron beams, in agreement with more complex formulations and with experimental data. When combined with the δ-ray distribution formula, these results provide a theory of the spatial distribution of ionization energy about the path of a rapidly moving ion, which is basic to theories of radiation damage and detection.

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Precision Measurement Of The Electronic G Factors Of The Alkali Metals, Paul A. Vanden Bout, Erol Aygun, Vernon J. Ehlers, Tuncay Incesu Dec 1968

Precision Measurement Of The Electronic G Factors Of The Alkali Metals, Paul A. Vanden Bout, Erol Aygun, Vernon J. Ehlers, Tuncay Incesu

University Faculty Publications and Creative Works

We have measured the ratios of the electronic g factors of Na23, Rb85,87, and Cs133 to that of K39, using the atomic-beam magnetic-resonance technique. The results are gJ(Na23)gJ(K39)=1.0000007 (2), gJ(Rb85,87)gJ(K39)=1.0000182 (2), and gJ(Cs1333)gJ(K39)=1.0001231 (3). These results, combined with the results of other researchers, yield the following absolute g factors for the alkali metals: gJ(Na)=-2.002297 (2), gJ(K)=-2.002295 (2), gJ(Rb)=-2.002332 (2), and gJ(Cs)=-2.002542 (2). These g factors, with the exception of the value for Cs, are in good agreement with theoretical values.

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Nuclear Spin, Hyperfine-Structure Separation, And Nuclear Magnetic Moment Of 18-Min Rb88, Paul A. Vanden Bout, Antoni Dymanus, Vernon J. Ehlers, Michael H. Prior Dec 1968

Nuclear Spin, Hyperfine-Structure Separation, And Nuclear Magnetic Moment Of 18-Min Rb88, Paul A. Vanden Bout, Antoni Dymanus, Vernon J. Ehlers, Michael H. Prior

University Faculty Publications and Creative Works

We have used the atomic-beam magnetic-resonance technique to measure the nuclear spin and the hyperfine-structure separation of 18-min Rb88 in the S122 electronic ground state. These results, combined with the Fermi-Segrè formula, yield the nuclear magnetic moment. Our results are: I=2, Δν=±1186.084(18) MHz, μI(uncorr)=±0.506(5) nm, μI(corr)=±0.508(5) nm. Present nuclear theory favors assignment of the negative sign to the value of the moment.

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Measurement Of Positron Annihilation Line Shapes With A Ge(Li) Detector, H. (Henry) P. Hotz, J. M. Mathiesen, J. P. Hurley Dec 1968

Measurement Of Positron Annihilation Line Shapes With A Ge(Li) Detector, H. (Henry) P. Hotz, J. M. Mathiesen, J. P. Hurley

Physics Faculty Research & Creative Works

We observed that the annihilation radiation photopeak in a Ge(Li) detector is considerably broader than that of a γ ray of the same energy. It seems reasonable to assume that the increased width is the result of the Doppler broadening of the annihilation photopeak, i.e., the longitudinal Doppler shift of the radiations is measured, while the transverse shift is measured in the usual angular-correlation experiments. By using a computer stripping program to remove the distortion produced by the finite energy resolution of our detector, we obtain momentum distributions in agreement with those which have been published. Only one detector is …

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Application Of The Method Of Lattice Statics To Interstitial Cu Atoms In Cu, John Flocken, John Hardy Nov 1968

Application Of The Method Of Lattice Statics To Interstitial Cu Atoms In Cu, John Flocken, John Hardy

John R. Hardy Papers

We have calculated the lattice distortion produced by a body-centered interstitial Cu atom in a Cu host lattice. The calculations have been carried out consistently on the basis of discrete lattice theory, using the technique of lattice statics which is based on the Fourier transformation of the direct-space equilibrium equations. The force constants for the perfect lattice have been taken from measured phonon-dispersion curves, and we have used Huntington's Born-Mayer potential to describe the interaction between the interstitial atom and the atoms of the host lattice. The comparison of our results with those obtained by earlier workers, using semidiscrete matching …

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Theoretical Analysis Of The Vibrations And Rotations Of The B¹[Sigma][Mu] State Of The Hydrogen Molecule, Sandra Zink Moody Nov 1968

Theoretical Analysis Of The Vibrations And Rotations Of The B¹[Sigma][Mu] State Of The Hydrogen Molecule, Sandra Zink Moody

Physics & Astronomy ETDs

Theoretical calculations of the rotational-vibrational constants of the B1Σ+u state of H2 were made using the Dunham analysis and by fitting equations to energy eigenvalues. The potential energy function for the nuclei used in the calculations was computed by W. Kolos and L. Wolniewicz using the variational technique. The power series used in the Dunham analysis made use of Stirling's central difference interpolation polynomial. The equilibrium separation Re found from the Born-Oppenheimer potential is 2. 429165 atomic units, differing from the Kolos-Wolniewicz value of 2.4288. Adiabatic corrections were taken into account through a …

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Critical Assessment Of The Polarized-Orbital Method In Atomic Scattering, Marvin H. Mittleman, Jerry Peacher Sep 1968

Critical Assessment Of The Polarized-Orbital Method In Atomic Scattering, Marvin H. Mittleman, Jerry Peacher

Physics Faculty Research & Creative Works

The method of polarized orbitals used in calculating electron-atom scattering amplitudes has two obvious flaws: the wave function is discontinuous, and the method is not variationally based. These are corrected in a somewhat arbitrary manner, and it is found that the results then depend upon a parameter of the theory sufficiently strongly that there are serious doubts about the predictive nature of the theory.

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Three-Quasiparticle Intruder State In Te125 And The Magnetic Moment Of Sb125, N. J. Stone, Richard B. Frankel, D. A. Shirley Aug 1968

Three-Quasiparticle Intruder State In Te125 And The Magnetic Moment Of Sb125, N. J. Stone, Richard B. Frankel, D. A. Shirley

Physics

The levels of Te125 have been studied using Sb125 nuclei, polarized at T=0.014°K in an iron lattice, and Ge(Li) detectors. The magnetic moment of Sb125 was determined as (2.59±0.03) μN. Levels (spins) were assigned at 35.9(3/2+), 145.4(11/2-), 322.2(9/2-), 443.7(probably 3/2+), 462.5(5/2+), 525.4(probably 9/2-), 636.1(7/2+), 642.3(7/2+), 671.6(5/2+) (energies in keV). The even-parity levels could be identified with levels calculated by Kisslinger and Sorensen. Using their wave functions, we calculated E2/M1 mixing ratios and branching ratios, finding quite good agreement. The odd-parity states are of special interest. The 11/2-145.4-keV state and 9/2-525.4-keV state …

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10th Annual Rocky Mountain Spectroscopy Conference Aug 1968

10th Annual Rocky Mountain Spectroscopy Conference

Rocky Mountain Conference on Magnetic Resonance

Program and abstracts from the 10th 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 19-20, 1968.

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Modified Dispersion Relations And Π Π Scattering, David J. George, Barbara N. Hale, Arnold Tubis Aug 1968

Modified Dispersion Relations And Π Π Scattering, David J. George, Barbara N. Hale, Arnold Tubis

Physics Faculty Research & Creative Works

The ππ S-wave scattering-length predictions of Weinberg have been tested by using dispersion sum rules for the infinite-energy cross section. Reasonable agreement is obtained with the infinite-energy cross section (≈15 mb) estimated from the factorization theorem for the Pomeranchon Regge residues. Experimental phase-shift data of Gutay et al., Walker et al., and Baton et al. are used in estimating the dispersion integrals. The analysis seems to rule out an I = 0 S-wave scattering length ⪞0.4μ-1.

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Numerical Evaluations Of The Virial Integrals, Li-Hwa Lee Jul 1968

Numerical Evaluations Of The Virial Integrals, Li-Hwa Lee

Masters Theses

No abstract provided.

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Formation Of Etchable Tracks In Dielectrics, Robert Katz, E. J. Kobetich Jun 1968

Formation Of Etchable Tracks In Dielectrics, Robert Katz, E. J. Kobetich

Robert Katz Publications

It is proposed that etchable damage is produced in dielectrics by energetic charged particles when a critical dosage of ionization energy is deposited at a critical distance from the ion's path by secondary electrons. Within the critical cylinder, molecular fragments more soluble than the parent molecule are formed. The radius of the critical cylinder is taken to be approximately 20 Å, as is appropriate to the passage of the etchant along the track and the diffusion of reaction products back to the surface. At the critical radius the dosage approximates doses producing bulk damage under γ irradiation. The proposed criterion …

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Width Of Heavy-Ion Tracks In Emulsion, E. J. Kobetich, Robert Katz Jun 1968

Width Of Heavy-Ion Tracks In Emulsion, E. J. Kobetich, Robert Katz

Robert Katz Publications

Profiles of the solid core of long, flat, ending tracks of heavy primary cosmic rays in Ilford G-5 emulsion have been measured by manually tracing their enlarged (3500X) photographic image. These measurements agree well in the ending 3000 μ of residual range (β <0.3) with a reformulated theory of track width based on computation of the spatial distribution of ionization energy. The measured core width in G-5 emulsion is the sum of the sensitized cylinder diameter, at which 6000 erg/cm3 of ionization energy is deposited by δ rays, and the diameter of a developed grain.

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Possible Trivacancy Contribution To Ionic Conductivity, Robert Fuller, M.H. Reilly Jun 1968

Possible Trivacancy Contribution To Ionic Conductivity, Robert Fuller, M.H. Reilly

Robert G. Fuller Publications

Fuller and Reilly [1], Fuller, Reilly, Marquardt and Wells [2], and Allnatt and Pantelis [3] have recently reported the results of measurements of the intrinsic electrical conductivity σ of RbCl, KCl and NaCl, respectively. All of these results showed an anomalous behavior of the log (σT) vs. T-1 plot at temperatures near the melting points of the various crystals. It is the purpose of this note to discuss the suggestion [4] that the anomaly may be due to a trivacancy mechanism.

The plots of the log (σT) vs. T –1 were found to have too …

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