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Photoelectron Angular Distributions Of S Electrons In Open-Shell Atoms, Anthony F. Starace, Robert H. Rast, Steven T. Manson

Anthony F. Starace Publications

It is shown that the photoelectron angular distribution of s electrons in an open-shell atom, having outer configuration ns²np^q, is not described by the asymmetry parameter β=2, as predicted by more approximate theories, but has dramatic variations with energy even within LS coupling. Calculations for the 3s subshell in Cl are presented as an example.

Light Scattering Studies Of Transverse Sound Wave And Molecular Motion In Benzonitrile, Scott L. Whittenburg, C. H. Wang

Chemistry and Biochemistry Faculty Publications

The zero‐frequency shear wave dip appearing in the depolarized Rayleigh spectrum in benzonitrile has been studied as a function of concentration and temperature. The solution study was carried out at constant viscosity equal to the viscosity of liquid benzonitrile at each temperature. The result indicates that the presence of shear wave fine structure does not depend on the collective orientational fluctuations. The orientational and vibrational relaxation times of benzonitrile were measured at various concentrations and temperatures. The orientational relaxation times show no concentration dependence at any temperature, suggesting that the pair correlation is negligible at all concentrations. The orientational relaxation …

Certainty And Chance In The Physical Sciences, Wytse Van Dijk

Pro Rege

No abstract provided.

Sio2-Si Film-Substrate Reflection Polarizers For Different Mercury Spectral Lines, A.-R. M. Zaghloul, R. M.A. Azzam

Electrical Engineering Faculty Publications

No abstract provided.

Measurement Of The Difference Between The Dynamic Nmr And Static Susceptibilites Of Superfluid 3he-B Using An Rf-Biased Superconducting Quantum-Interference Device, Richard A. Webb

Faculty Publications

The temperature-dependent susceptiblity of superfluid ³He-B has been measured both statically and via a pulse technique in a field of 309 G using an rf-biased superconducting quantum-interference device (SQUID). In the pressure range 26.5 to 18 bar, the dynamic NMR susceptiblity agrees qualitatively with the theoretical weak-coupling predictions for the Balian-Werthamer state. However, the static susceptiblity, measured using the same rf-biased SQUID and detection system, is significantly smaller thatn the dynamic susceptibility.

Light Scattering Studies Of Rotational And Vibrational Relaxations Of Acetonitrile In Carbon Tetrachloride, Scott L. Whittenburg, C. H. Wang

Chemistry and Biochemistry Faculty Publications

The rotational and vibrational relaxation times of acetonitrile–carbon tetrachloride solutions were investigated as a function of concentration, viscosity, and temperature using depolarized Rayleigh and Raman scattering. Using a Fabry‐Perot interferometer and single frequency laser source, we have shown that reliable results for the single particle orientational correlation times (τ_s) for CH₃CN can be obtained by carrying out a concentration dependent depolarized Rayleigh scattering study. Raman scattering was shown to yield inconsistent results for τ_s in CH₃CN. At constant viscosity, it was found that the Rayleigh scatteringrelaxation time (τ_Ray) of CH_{3 …}

Infrared Observations Of Hii Regions And Comet West, Paul A. Heckert

Physics & Astronomy ETDs

In Chapter 1, I outline the methods of making ground-based infrared observations. I concentrate on the observational procedures rather than the instrumental design. Near-infrared observations of S 156A, _S 158A, S 159A, S 162A₁, S 228, and G 45. 5 + 0 .1 (#2) made with a beam size of ̴1 are used to estimate the total near infrared flux. After correcting for the line of sight extinction the near infrared luminosities are greater than the Lyman-α luminosities inferred from radio observations. A strong double peaked infrared source was discovered near the region of G 25.3-0.1. The infrared …

Plasma Sheath Analysis By Computer Simulation, Leo J. Rahal

Physics & Astronomy ETDs

The time development of a fully ionized, dense two-component plasma is investigated through the use of a one-dimensional particle simulation code. The plasma is initially composed of two distinct regions. One region is a uniform plasma in which electrons and ions are at the sane temperature and have no electric fields due to charge separ­ation. The other region contains a charge separation of electrons and ions resulting in an electric field. There also exists an electron current which produces a confining magnetic field. This is the sheath region between the neutral plasma and the confining magnetic field. The simulation occurs …

A Study Of He+ + Ar Collisions At Energies Between 600 Ev & 1500 Ev, Alton Dull Jr.

Masters Theses & Specialist Projects

This investigation was undertaken in order to confirm and to extend earlier studies of processes whereby energy and angular momentum are transferred from external to internal degrees of freedom in low velocity collisions between ions and atoms. Specifically, this investigation sought to verify the proper functioning of a device designed to study low velocity atomic and molecular collisions, to confirm results obtained in an earlier study of spectra produced by collisions of He⁺ions with argon atoms, and to extend the energy and wavelength ranges of this study to 1500 eV and 6200 Å, respectively.

The data was in …

The Effects Of Electron Irradiation On Mosfets, Mark D. Skeldon

Physics Theses & Dissertations

The characteristics of n and p-channel MOSFETs have been investigated while irradiated with electron radiation from Strontium 9Ø. The drain current vs. gate voltage of the p-channel MOSFET and the threshold voltage changes in n and p-channel MOSFETs have been studied with and without aluminum shielding. The switching characteristics and threshold voltage changes of COS/MOS dual input NAND gates have been investigated while exposed to electron radiation. Various methods of annealing the radiation damage to these devices is discussed.

Measurement Of The Xenon Σ3/2:Σ1/2 Branching Ratio Within The Xe 5s5p66p(1P1) Resonance, Peter C. Kemeny, James A. R. Samson, Anthony F. Starace

Anthony F. Starace Publications

Photoionization of the 5p6 shell in xenon leaves the ion in either the 5p⁵(²P_3/2) or np⁵(²P_1/2) state. Measurements of the ²P_3/2 : ²P_1/2 branching ratio are reported within the Xe 5s5p⁶6p(¹P₁) resonance and fitted to a new theoretical expression. The maximum value of the ratio as determined by a two-parameter fit of theory to experiment is 8.8 ± 0.5 within the resonance, almost six times the nearly constant value of 1.55 found outside any resonance.

Theory And Applications Of An Atoms In Molecules Approach To The Xα -Scf Method, J. Tylicki, R.J. Hood, Gordon A. Gallup, C.J. Eckhardt

Gordon Gallup Publications

We have studied the Xα -SCF problem with an atoms in molecules approach. LCAO-molecular orbitals are used and the molecular charge and exchange densities are built up from atomic contributions. We have applied our method to CH₃F with subsequent comparison to ab initio calculations. The Xα -SCF dipole moment of CH₃F is 1.76 D compared with an experimental value of 1.79 D. We also give calculations of TCNQ and TTF with comparisons to recent Xα calculations using the overlapping sphere modification of a muffin-tin potential. Quadrupole moments for TCNQ and TTF have also been determined. The …

Mössbauer Study Of Spin Alignment In Substituted Lithium Ferrites, C. R. Abeledo, Richard B. Frankel

Physics

To explain the decrease of magnetic moment in zinc substituted lithium ferrites Dionne has proposed a model which includes canting of the B sublattice moments as zinc is substituted in the A sublattice. Mössbauer spectroscopy in external magnetic fields is applied to investigate the existence of canting in (Li₀,₅Fe₀, ₅)_1-xZn_xFe₂O₄ with x = 0 and x = 0.3. The samples used were either polycrystalline powders or circular disks cut from pressed blocks and lapped down to a thickness of 0.1 mm. In the x = 0 …

Theoretical Studies Of Nucleic Acid Sugar Ring Analogs, Ali-Reza Hashemi-Attar

Physics & Astronomy ETDs

Extended Hueckel theory (EHT) was used to study analogs of sugar rings in nucleic acid monomers. The energy gradient in a variable metric algorithm was used to find the potential energy along the pseudorotation path. Use of the energy gradient made it possible to permit 34 degrees of freedom in a molecule. Seven molecules and their isomers were studied. These were: 3-hydroxy2-methyl tetrahydrofuran, 2-ami no-4-hydroxytetrahydrofiJran, 5-ami no3-hydroxy-2-methyltetrahydrofuran (deoxyribonucleic acid analog), 3,4-dihydroxy-2-methyltetrahydrofuran, 2-amino-3,4-dihydroxytetrahydrofuran, 2-amino-5-methyltetrahydrofuran, and 2-amino-3,4-dihydroxy-5-methyltetrahydrofuran (ribonucleic acid analog).

It was shown that the difference in sum of total overlap populations (TOP) for all pairs of atoms between two related conformations …

Electron Tunneling, Charge Transfer, And The Intermolecular Forces Between Two H2 Molecules, Gordon A. Gallup

Gordon Gallup Publications

The spherically averaged van der Waals potential for the system H₂–H₂ has been calculated using a nonorthogonal CI method based on SCF orbitals for the individual molecules. With suitable restrictions on the CI calculation we have isolated various contributions to the van der Waals potential, and have found that charge transfer and dispersion effects are comparable to distances corresponding to the potential minimum. The charge transfer contribution is further discussed in terms of a mechanism involving electron tunneling through the intervening space between the molecules. Our calculation gives a spherically averaged van der Waals well depth of …

Fermi-Surface Topology Of 2h-Tase2 At 4.2k, Paul D. Hambourger

Physics Faculty Publications

The magnetoresistance of single-crystal 2H-TaSe₂ in the commensurate charge-density-wave state has been measured at 4.2 K in magnetic fields up to 48 kG. The results indicate that the Fermi surface supports open orbits parallel to the [0001] direction for all orientations of magnetic field in the (0001) plane. No evidence of open orbits in other directions was observed.

Can Physics Develop Reasoning?, Robert Fuller, Robert Karplus, Anton E. Lawson

Robert G. Fuller Publications

The life of every physicist is punctuated by events that lead him to discover that the way physicists see natural phenomena is different from the way non-physicists see them. Certain patterns of reasoning appear to be more common among physicists than in other groups. These include:
• focusing on the important variables (such as the force that accelerates the apple, rather than the lump it makes on your head);
• propositional logic ("if heat were a liquid it would occupy space and a cannon barrel could only contain a limited amount of heat, but this is contrary to my observations, …

Differential Energy-Loss Cross Sections For Ionization Of Atomic Hydrogen By 25-200-Kev Protons, John T. Park, John E. Aldag, Jacob M. George, Jerry Peacher, Jim H. Mcguire

Physics Faculty Research & Creative Works

Ionization continuum cross sections, differential in energy loss, have been determined from the energy-loss spectra of 25-, 50-, 75-, 145-, and 200-keV protons scattered from atomic hydrogen. The theoretical differential cross sections in the Glauber and Born approximations that are presented show that the theory and the experimental results for 200-keV proton impact agree very well, but below 200 keV there are differences. These differences, which are more pronounced at the lower projectile energies, may be explained in terms of charge transfer to the continuum, which is not treated in our Born and Glauber calculations of direct Coulomb ionization. The …

Nuclear Spin-Lattice Relaxation And Activation Energies Of Tunnelling Methyl Groups, Peter A. Beckmann, S. Clough

Physics Faculty Research and Scholarship

The coupling of lattice vibrations with the rotational motion of hindered methyl groups is considered. It is shown that the apparent activation energy for methyl group rotation is determined at relatively high temperatures by the methyl group torsional energy splittings, but at low temperatures it depends on the frequencies of short-wavelength lattice modes which couple relatively strongly with methyl-group rotation. The temperature dependence of the proton spin lattice relaxation time from 6 to 50K is reported for three samples containing methyl groups whose tunnelling frequencies have previously been measured very precisely. They are 4-methyl-2,6-ditertiarybutylphenol (MDBP) and two deuterated derivatives. The …

Nuclear Spin Relaxation And Centrifugal Distortion Effects In Dilute Silane Gas, Peter A. Beckmann, E. E. Burnell

Physics Faculty Research and Scholarship

We have measured the proton longitudinal spin relaxation rate in dilute gaseous silane (SiH₄) between 10⁻² and 1 amagats and are able to observe the influence of rotational Q branch centrifugal distortion transitions.

Compton's 'Crucial Test' - Theoretical Preconceptions And Experimental Interpretation, Roger H. Stuewer

Journal of the Minnesota Academy of Science

Arthur Holly Compton, as a result of his own research and confidence in the validity of classical electrodynamics, was convinced in 1921 that homogeneous x-rays and gamma rays could be affected in only two possible ways when passing through matter: either they gave rise to "truly scattered" radiation of the same wavelength as that of the incident rays, or they excited "fluorescent" radiation of a longer wavelength. When Compton was led to carry out experiments using homogeneous x-rays and actually found secondary radiation of longer wavelength, he regarded his result as a crucial test between the "truly scattered" and the …

Atomic Numbers Revalued, Frank H. Meyer

Journal of the Minnesota Academy of Science

As a general physical theory, the Reciprocal System of D.B. Larson covers all physical fields, including atomic physics . Inasmuch as all of the conclusions reached in the theoretical development are derived entirely by deduction from the basic postulates of this system, the conclusions provide information that is completely independent of observation. The theoretical development indicates that the Mosely atomic number mathematical formula is quite right, and the Rutherford-Bohr-Mosely nuclear atom physical interpretation of atomic number is seriously wrong. The discrete units constituting atoms evidently are not neutrons and electrically charged particles. Nor are atoms made up of parts, a …

Four-Color And Hβ Photometry Of Stars In Ngc 7654 And M25, Edward G. Schmidt

Edward Schmidt Publications

Four-color and Hβ photometry has been obtained of stars in the galactic clusters NGC 7654 and M25. An analysis of these data shows variable extinction in both clusters. The distance modnlus of NGC 7654 is found to be 10^m.99 ± 0.2 and that of M25 is 8^m.68 ± 0.1.

Eclipsing Systems In Star Structures. Iii. Early-Type Contact System Bh Centauri, Kam-Ching Leung, Donald P. Schneider

Department of Physics and Astronomy: Faculty Publications

Close to 1000 photoelectric observations of BH Cen in the yellow, blue, and ultraviolet regions were analyzed. The period found was 0.791616 days. The depths of minima were about equal, and were more than 1 magnitude! A photometric solution was derived with the Wilson and Devinney model. The binary is an overcontact system with primary and secondary masses equal to 10 M_?. Based on its membership in IC 2944 and the size of the primary radius, BH Cen may be another example of a zero-age contact system.

Electron And Ion Temperatures—A Comparison Of Ground-Based Incoherent Scatter And Ae-C Satellite Measurements, R F. Benson, P Bauer, L H. Brace, Herbert C. Carlson, J Hagen, W B. Hanson, W R. Hoegy, M R. Torr, R H. Wand, Vincent B. Wickwar

All Physics Faculty Publications

The Atmosphere Explorer-C satellite (AE-C) is uniquely suited for correlative studies with ground-based stations because its on-board propulsion system enables a desired ground station overflight condition to be maintained for a period of several weeks. It also provides the first low-altitude (below 260 km) comparison of satellite and incoherent scatter electron and ion temperatures. More than 40 comparisons of remote and in situ measurements were made by using data from AE-C and four incoherent scatter stations (Arecibo, Chatanika, Millstone Hill, and St. Santin). The results indicate very good agreement between satellite and ground measurements of the ion temperature, the average …

Energy And Angular Distribution Of Electrons Ejected From Argon By 5-Kev To 1.5-Mev Protons, T. L. Criswell, L. H. Toburen, M. Eugene Rudd

M. Eugene Rudd Publications

Cross sections, differential in emission energy and angle, have been measured for the ejection of electrons in collisions of H⁺ with argon gas targets. Incident-proton energies studied were from 5 keV to 1.5 MeV and electron emission angles ranged from 10° to 160°. Integration of the double-differential cross sections over emission angle and energy yield results in good agreement with direct measurement of total ionization cross sections. The electron distributions are compared to two plane-wave Born-approximation calculations, one using Hartree-Slater wave functions and the other using Hartree-Fock wave functions in the 3p-εd channel.

Search For Volume Anomaly In Paramagnetic Zrzn2, Paul D. Hambourger

Physics Faculty Publications

No abstract provided.

The Plasma Line Revisited As An Aeronomical Diagnostic: Suprathermal Electrons, Solar Euv, Electron‐Gas Thermal Balance, Herbert C. Carlson, Vincent B. Wickwar, G P. Mantas

All Physics Faculty Publications

Spectra of plasma wave intensities (kT_p) in the ionosphere over Arecibo are calculated and compared with those from observations of the plasma line intensity. This approach involving directly observed quantities avoids the uncertainties that have plagued past comparisons with photoelectron theory. In addition, careful comparisons in physically relevant segments of the spectra show that any significant increase in the magnitude of the solar EUV flux would lead to a contradiction of the observed plasma wave intensities. Further, the comparisons indicate that resolution of the thermal electron‐gas heat balance problem must be sought through better heat transfer rates (e.g., …

Positron Annihilation In Copper, K. White, W. H. Rickles, Thomas Listerman

Physics Faculty Publications

No abstract provided.

A Geomagnetic Survey Of Greene County, Ohio, V. E. D. Obot, Paul J. Wolfe

Physics Faculty Publications

No abstract provided.