Physical Sciences and Mathematics Commons^™

Production And Decay Of Double L Vacancies In Argon And Phosphorus, M. Eugene Rudd, B. Fastrup, P. Dahl, F. D. Schowengerdt

M. Eugene Rudd Publications

Measurements have been made at two laboratories which indicate that the structure reported at 450-550eV in the electron spectrum from Ar⁺-Ar collisions by Ogurtsov, Flaks, and Avakyan is spurious. It is argued that the double L vacancies which they invoke to explain the structure are more likely to decay by the two-step Auger process L ²→LM²→M⁴ than by the one-step process L²→M³ suggested by these authors. Evidence supporting this is found in our electron spectra from P⁺-Ar collisions, where it is known from energy-loss and charge-state measurements that double …

Autoionization Of He And Autodetachment Of He- Following Bombardment By H+, H2+, He+, And He Atoms, F. D. Schowengerdt, S. R. Smart, M. Eugene Rudd

M. Eugene Rudd Publications

Presented here are experimental results of a study of the systematics of electron emission from discrete states of He and He- as produced by H⁺, H₂⁺, He⁺, and He impacts. The results were obtained by energy analysis of the electrons emitted at angles of 10° to 160°. Projectile energies ranged from 20 to 150 keV. Differential and integrated cross sections are presented for emission of electrons from the 2s² (¹S), 2s2p(³P), the sum of the 2p² (¹D) and 2s2p(¹P) autoionizing levels of He, …

Quasifree (P,Pα) Scattering On ⁶Li, ²⁴Mg, ²⁸Si, ⁴⁰Ca, ¹⁴⁰Ce, And ²³²Th At 156 Mev, D. Bachelier, M. Bernas, Oleksa-Myron Bilaniuk, J. L. Boyard, J. C. Jourdain, P. Radvanyi

Physics & Astronomy Faculty Works

Knockout of α particles by 156-MeV protons from ⁶Li, ²⁴Mg, ²⁸Si, ⁴⁰Ca, ¹⁴⁰Ce, and ²³²Th has been used to investigate the A dependence of α clustering in nuclei. Protons and α particles were detected in coincidence under conditions of quasifree scattering. Corresponding reaction cross sections were measured. Cross sections for ²⁴Mg and ⁴⁰Ca were found to be about 2 orders of magnitude lower than for ⁶Li. The cross section for ²⁸Si was found to be about 3 times lower than that for ²⁴Mg and ⁴⁰Ca. Upper limits of the integrated cross sections for ¹⁴⁰Ce and ²³²U are still compatible with …

Appendix A: The Use Of The Personalized System Of Instruction (Psi)

Calculus-Based General Physics

STUDY MODULES FOR THE USE OF THESE CBP MODULES

Recommended

1. What is the Philosophy of PSI?

2. How Do I Manage This System?

3. The Care and Feeding of Student Tutors

Optional

4. How to Plan the Content of a Keller Plan Course

5. How to Design a Study Module

6. How to Write Learning Objectives

A Study Of Gas-Surface Interactions Through Sticking Coefficient, Condensation Coefficient And Sublimation Rate Measurements, Charles E. Bryson Iii

Doctoral Dissertations

"The behavior of the sticking coefficient of CO₂ on an H₂O substrate as a function of time is interpreted in terms of a microscopic nucleation theory. For a substrate temperature near 75 K and an incident flux near 10¹³ molecule cm⁻² sec⁻¹, a critical cluster size of four molecules and and activation energy of nucleation of 22 ± 2.4 Kcal mole⁻¹ is obtained. The analysis treats the nucleation processes as continuous rather than as a discontinuous process at some critical temperature.

In addition the same molecular beam apparatus used for the above experiment was used to measure the condensation …

The Contribution Of Phonon-Induced Tunneling To Donor Esr Spectral Narrowing In Semiconductors, David Lawrence Meier

Masters Theses

"The narrowing of donor electron spin resonance spectra with increasing donor concentration N_D and increasing temperature T has been observed in semiconductors in the past. One proposed explanation for this phenomenon has been narrowing due to electron motion caused by phonon-induced tunneling (hopping) between donor sites. According to the Anderson narrowing theory, the line width of the narrowed line can be expressed in terms of the average square spread of the non-narrowed spectrum, < H²>_ave, and the average frequency of electron motion, ω_n. Previous work has been done on narrowing by hopping, but rigorous expressions for ω …

Total Electron Impact Ionization Cross Section In Rubidium From Threshold To 250 Ev, Kaare J. Nygaard, Yu Bong Hahn

Physics Faculty Research & Creative Works

A study of ionization in rubidium has been made in a crossed atom-electron beam apparatus. At an electron energy of about 10 eV there is a maximum in the cross section corresponding to the maximum probability for removal of the 5s valence electron. At 16.5 eV we have observed a new peak that is caused by the mechanism of autoionization. For energies below 30 eV there is a good agreement, both in shape and magnitude, between the present measurements and the empirical formula of Lotz. The over-all uncertainty in the measurements is ± 12% which is mostly accounted for by …

Carbon Interstitial In The Diamond Lattice, C Weigel, David Peak, J W. Corbett, R P. Messmer, G D. Watkins

All Physics Faculty Publications

Linear-combination-of-atomic-orbitals-molecular-orbitals cluster calculations using the extended Hückel theory are carried out for the interstitial carbon in the diamond lattice. The results suggest that the interstitial configuration is not the tetrahedral or hexagonal site, as has been previously assumed, but is instead an "interstitialcy" configuration, i.e., either a split- 〈100〉 interstitial (which our results favor) or a bond-centered interstitial. The predicted minimum-energy configuration changes with charge state, suggesting that the interstitial in the diamond lattice is a possible example of the Bourgoin mechanism of athermal migration of a defect in the presence of ionizing radiation.

Ionization‐Enhanced Diffusion: Ion Implantation In Semiconductors, J Bourgoin, David Peak, J W. Corbett

All Physics Faculty Publications

A model for the diffusion of implanted interstitials during implantation is introduced and shown to be able to account for the tails observed in ion profiles. It is argued that mechanisms of ionization‐enhanced diffusion can explain some of the anomalous diffusion mechanisms observed in semiconductors. Indications for the existence of such mechanisms in the field of ion implantation in semiconductors are discussed.

Charge Transfer Between Oˉ Ions And O₂ Molecules In The Ground State And Singlet Delta Excited State, Ronald Floyd Mathis

Doctoral Dissertations

"A crossed-beam apparatus has been built and 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 10,000 eV.

The cross section for charge transfer between O⁻ and ground state O₂ was found to peak at about 5 keV, as predicted on the basis of the Rapp and Francis theory. 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 …

Hall Effect Measurements Of The Net Ionic Mobility In Nacl, Nabr And Nai, Suman Kumar Hukku

Doctoral Dissertations

"Ac Hall effect measurements of the net ionic mobility, µ_H, in "pure" NaCl, NaBr and Nal were made over their intrinsic temperature ranges extending up to about 250⁰ C below the crystal melting point. A well characterized detector system was employed which provided a mobility sensitivity ≥ 2 x 10^-4 cm² · V^-1 · s^-1. Complementary electrical conductivity, σ, data was also collected. The charge transport was assumed to be due to Schottky defects and both cation and anion contributions were considered. The high temperature anion contribution to mobility was clearly demonstrated by …

A Stochastic Theory Of The Stepwise Growth Of Ice Crystal Surfaces, Andreas Kasimir Goroch

Doctoral Dissertations

"Previous theories have had limited success in explaining the presence of a peak in the behavior of the rate of advance of a step on an ice crystal surface with respect to temperature. In the present work we examine the temperature dependence of the advance of steps on the basal face of an ice crystal from several points of view. An alternate derivation is presented for the random motion of adsorbents on a cubic lattice with absorbing points, and this theory is applied for the advance of a step on an ice surface. The velocity of step advance according to …

Logical Transition From Magnetic Poles To Current Loops, H. E. Mccloud

Journal of the Arkansas Academy of Science

Consideration of the relationship between the magnetic field produced by a magnetic shell and that produced by a current loop requires the evaluation of the line integral ɸH̅ • dl̅, where a portion of the path must cross the dipole layer. The correct line integral to be evaluated must be ɸB̅ • dl̅. The evaluation of this integral leads immediately to the correct Maxwell equation in ∆ x H̅. Gaussian units are used.

A Two Dimensional Jet Flowing Into A Semi-Infinite Flow Field With An Ambient Velocity, Michael Leonard Crane

Dissertations, Theses, and Masters Projects

No abstract provided.

Note On The Poisson Distribution, I. Adawi

Physics Faculty Research & Creative Works

No abstract provided.

Absolute Differential Elastic- And Inelastic-Scattering Cross Sections In 25-140 Kev He+ + He Collisions, Victor Pol, Walter Kauppila, John T. Park

Physics Faculty Research & Creative Works

Data obtained as energy-loss spectra at angles from 0 to 7.3x10-3 rad (c.m.) with typical energy-loss resolution of 0.7 eV and angular resolution of 2x10-3 rad (c.m.) were used to calculate average differential cross sections dσdΩav for elastic scattering, direct excitation of the individual He(n=2) states, and direct excitation of the He+(n=2) states. The total cross section for excitation of the He(n=2) states obtained by integrating the differential cross sections was found to be 20x10-18 cm2 at 25 keV (lab) decreasing to 7x10-18 cm2 at 140 keV. At incident lab energies below 100 keV the He(2S2) and He(2P3) states dominate …

Laser Scattering Measurements Of Droplet Growth In Binary Mixtures. Ii. H2o And Argon H2o And Helium, M. A. Viettit, Burton Schuster

Physics Faculty Research & Creative Works

Water droplet growth rates in a Wilson cloud chamber were measured in Ar-H2O and He-H2O media. These rates were determined in the size range 0.45-10.0 u.m by detection of oscillations in the intensity of polarized light from a He-Ne laser source scattered at 30° by the droplet population. Pressure and initial temperature were measured in the chamber for use in the computation of three droplet growth theories for comparison to experiment. Experiments were conducted in supersaturations ranging from 1.04 to 3.45.

Possible Applications Of Surface Electromagnetic Waves To Measure Absorption Coefficients, Ralph William Alexander, Robert John Bell, C. A. Ward, James Roger Weaver, I. L. Tyler, B. Fischer

Physics Faculty Research & Creative Works

We Show that Surface Electromagnetic Waves Can Probably Be Used to Measure the Absorption Coefficients of Materials overlaying Metals. the Proposed Experimental Method is Illustrated in the Infrared Frequency Range using Water, Teflon, and Polyethylene as Sample Materials.

Gaas Laser Experiments For The Undergraduate Laboratory, R. E. Robert, Daniel J. Jones, Kaare J. Nygaard

Physics Faculty Research & Creative Works

No abstract provided.

Penning Ionization Of Zn And Cd By Noble-Gas Metastable Atoms, L. A. Riseberg, William F. Parks, Laird D. Schearer

Physics Faculty Research & Creative Works

The Penning-ionization cross sections for He, Ne, Ar, and Kr metastable atoms with Zn and Cd have been measured in a pulsed afterglow. Within the framework of existing theories we have determined those parameters which are of importance in collisions of this type. We find that our data are internally consistent if the cross sections are proportional to the cube of the "hard-sphere" radii and the effects of selection rules are included. A theoretical basis for this dependence is suggested. © 1973 The American Physical Society.

On The Effect Of Cesium In Photoionization Laser Plasmas, Kaare J. Nygaard

Physics Faculty Research & Creative Works

A number of photoionization mechanisms and how they can be used to generate large-volume laser plasmas are discussed. Reaction rates for two-step photoionization of the cesium atoms as well as formation of molecular ions (Cs2+) are estimated. The necessary cross-section data were obtained from related research in thermionic energy converters. © 1973, IEEE. All rights reserved.

Auger Satellites Of The L₂₃ Auger Emission Bands Of Al, Si, And P, John Junior Melles

Doctoral Dissertations

"In this study a detailed investigation of the high energy satellites of the L₂₃ Auger emission bands of Al, Si, and P was made. The satellites are interpreted as arising from double ionization of the L₂₃ shell rather than from a plasmon gain process. The parent-satellite energy separations, ΔE, between like structures were determined and were found to be consistently smaller than the volume plasmon energies measured for the same samples. A comparison of Si and SiO revealed no evidence that ΔE for Si is dependent on the volume plasmon energy of the sample.

The satellite threshold excitation …

Model Correction For The Formation Of Amorphous Silicon By Ion Implantation, John Robert Dennis

Masters Theses

"ESR has been used to study the formation of an amorphous layer in silicon by ion implantation. The room temperature implants were done at 20 keV with low dose rates. The critical dose was determined as a function of ion mass for six different ion species. Our experimental heavy ion results agree with those found by other ESR investigators at higher energy, but are not the same for light ions. However, our light and heavy ion results agree with electron microscope measurements for low energy implants. An energy-independent model for the formation of amorphous silicon by ion implantation has …

Temperature Dependence Of The Formation Of An Amorphous Layer In Ion-Implanted Silicon, Gary Keith Woodward

Masters Theses

"Electron spin resonance (ESR) has been used to study the temperature dependence of the formation of an amorphous damaged layer produced by ion implantation in silicon.

Undoped silicon wafers were implanted with N⁺, Ar⁺, and Kr⁺ ions at 20 keV and dose rates less than .36 µa/cm². Implant temperatures ranged from room temperature to 250°C. ESR measurements were made at room temperature on these wafers. The only ESR signal found was that associated with amorphous silicon. The ESR signal amplitude for a given ion and temperature increased approximately linearly with dose up to …

The Design And Calibration Of A Vibrating Sample Magnetometer, Donald Dwight Hoffman

Masters Theses

"The design and calibration of a vibrating sample magnetometer is described. The sample motion was in the direction of the external magnetic field which was produced by a superconducting solenoid. The maximum external magnetic field was 70 kilogauss. Sample temperature could be varied from 77°K to 1000°K with a vacuum jacketed furnace. The maximum temperature was obtained with approximately 27 watts. The instrument was calibrated to 1% with a spherical nickel sample"--Abstract, page ii.

Nuclear Charge Distribution Of Tm¹⁶⁹, Eugene Clark Deci

Graduate Dissertations and Theses

The distribution of electrical charge in the nucleus of Tm¹⁶⁹ was determined by measurement of the energies of the X rays of muonic atoms of Tm¹⁶⁹.

The values of the energies of the K X rays and the L X rays were calculated from a model assuming an anisotropic Fermi distribution of charge, and compared to the treasured values. The assumed distribution is a function of three parameters; a half radius, a surface thickness, and a measure of the anisotropy.

The values of the parameters were varied to find the values that gave the best agreement with …

The Weakly Coupled Polaron, Kou-Ying Yang Moravan

Graduate Dissertations and Theses

The Green's Function technique has been used to investigate the properties of weakly coupled longitudinal optical polarons. By taking into consideration the contribution of the multi-phonon and the phonon-cross-exchange diagrams in the self-energy, a vertex correction has been made to the lowest order diagram. The real part and the imaginary part of the self-energy are obtained. The dispersion relationship obtained by this approximation gives the ground state energy which is lower than the upper bound obtained from the variational method. Also, the spectral weight function for several momentum values has been calculated. It shows that the quasi-particle description is good …

Nuclear Charge Distribution Of ¹⁸¹Ta, David Edward Mcloughlin

Graduate Dissertations and Theses

The energies of the x rays emitted by the muonic atom of ¹⁸¹Ta were measured by a Ge(Li) solid state detector. From the clustering of these gamma rays it was possible to identify the transitions of the muonic atom which produced them. When a form is chosen for the nuclear charge distribution, a theoretical spectrum can be calculated…The parameters ��, c, and t can then be chosen to make the calculated spectrum coincide for the 3D-2P, and 2P-1S transitions with the observed spectrum.

The first part of the calculation was performed in the following way. The monopole part of …

Absolute Differential Elastic And Inelastic Cross Sections In 25-140 Kev He⁺ + He Collisions, Victor Pol

Doctoral Dissertations

"The UMR heavy-ion energy-loss spectrometer has been modified to study the angular dependence of elastic and inelastic scattering for 25-140 keV He⁺ incident on He. The data were obtained as energy-loss spectra at angles from 0 to 7.3 x 10^-3 rad (c.m.) with energy-loss resolution of 0.6 to 1.0 eV and angular resolution of 1.2 x 10^-3 to 2.4 x 10^-3 rad (c.m.). From the spectra we have calculated average differential cross sections for elastic scattering, direct excitation of the individual He(n=2) states and direct excitation of the He⁺(n=2) states. By integrating the differential …

Extension Of Belyaev-Zelivinski Method Of Rotation As Intrinsic Nuclear Excitation, Jeffrey W. Gray

Graduate Dissertations and Theses

The method of Belyaev and Zelevinski for handling the rotational collective states of deformed nuclei has been extended. It is shown how a [J(J+1)]² term naturally occurs in the energy spectrum of a rotational band for even-even nuclei. This is accomplished by modifying the assumption that Belyaev and Zelevinski imposed on their |n> states. This leads to a definite relationship between the coefficient of the J(J+1) and [J(J+1)]² terms in the energy spectrum. This technique is applied to a single isolated j-level and to an arbitrary level scheme.