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Full-Text Articles in Physics
Electron Transmission Spectroscopy In Atomic Hydrogen, L. Sanche, Paul Burrow
Electron Transmission Spectroscopy In Atomic Hydrogen, L. Sanche, Paul Burrow
Paul Burrow Publications
An electron transmission experiment is used to study the resonances in the total scattering cross section of atomic hydrogen below the threshold of the first excited state. The three lowest resonances, designated 1S, 3P, and 1D, are observed and their energies and decay widths are found to be in good agreement with the values predicted theoretically using close coupling with correlation.
Irradiation Equivalence, Robert Katz, S. C. Sharma, M. Homayoonfar
Irradiation Equivalence, Robert Katz, S. C. Sharma, M. Homayoonfar
Robert Katz Publications
Recent analyses of track structure show that the parameters describing a radiation field are not separable from those describing a detecting system; that is, it is impossible to write an expression describing the effect of irradiation as a product of 2 factors, one of which contains only parameters describing the detecting system, while the other contains parameters describing only the radiation field. From this perspective it is difficult to understand the use of a “quality factor,” applicable to all biological substances and given as a function of the “effective LET,” for the conversion of rads to rems. One cannot define, …
Raman Scattering From Zns Polytypes, J. Schneider, Roger D. Kirby
Raman Scattering From Zns Polytypes, J. Schneider, Roger D. Kirby
Roger Kirby Publications
The Raman spectra of the 2H and 4H structures of ZnS have been measured between room temperature and 60 K, and compared with the spectra from zinc blende ZnS. The observed phonons in each case are in good agreement with those expected from the known structural differences.
Frenkel Defects In Alkali Halides, Paul Schulze, John Hardy
Frenkel Defects In Alkali Halides, Paul Schulze, John Hardy
John R. Hardy Papers
The method of lattice statics and the deformation dipole model have been applied to Frenkel defects in ionic crystals. For isolated interstitials, all short-ranged repulsive and Coulomb-defect host-lattice ion forces were evaluated at the relaxed configuration. The zero-order Coulomb force was allowed to act on the remainder of the host-lattice ions past first neighbors. We have calculated Frenkel-pair formation energies, ionic displacements, and ionic polarizations in the twelve Na, K, Rb halides. Our results show over all that, in ionic crystals of the rocksalt structure, Schottky defect pairs are more likely to be present than Frenkel defect pairs.
Research Project For Undergraduates: Ionic Thermoconductivity In Dielectrics, Richard M. Fuller, Robert Fuller
Research Project For Undergraduates: Ionic Thermoconductivity In Dielectrics, Richard M. Fuller, Robert Fuller
Robert G. Fuller Publications
Research projects for undergraduates should satisfy several conditions with regards to the physical insight, experimental manipulation, data analyses, and time for the experimental run that are required of the students. These conditions are satisfied by the study of dipole relaxations in dielectric materials using the method of ionic thermocurrents (ITC). ITC can be used to determine the concentration, activation energy, and relaxation time of dipoles in a dielectric. The necessary equipment and some possible research projects are discussed.
Schottky Defects In Alkali Halides, Paul D. Schulze, John R. Hardy
Schottky Defects In Alkali Halides, Paul D. Schulze, John R. Hardy
John R. Hardy Papers
The method of lattice statics and the deformation-dipole model have been applied to Schottky defects in ionic crystals in approximations higher than zero order. For an isolated vacancy, all host-lattice-ion potential energy functions for short-ranged repulsive and Coulomb-defect forces were expanded to terms quadratic in the displacements and dipole moments, and the resulting forces were allowed to act on the first and/or second neighbors to the vacancy. The zero-order Coulomb force was allowed to act on the remainder of the host-lattice ions past first and/or second neighbors. The vacancy and Schottky-pair-formation energies in the 12 Na, K, Rb halides have …
Potential-Barrier Effects In Photoabsorption. I. General Theory, Anthony F. Starace
Potential-Barrier Effects In Photoabsorption. I. General Theory, Anthony F. Starace
Anthony F. Starace Publications
This paper combines parts of the theories of spectroscopy, collisions, and autoionization to provide a unified framework for a quantitative theory of experimental data on 4d-shell photoabsorption in rare earths. The calculations by atomic theory are intended for tentative application to solids. The theory should also apply to 3p-shell photoabsorption in the transition metals and to other cases where the effect of a potential barrier is crucial. A prescription is given for the ab initio numerical calculation of total and partial photoabsorption cross sections, as well as of the profiles, energies, and widths of resonances. A …
Potential-Barrier Effects In Photoabsorption. Iii. Application To 4D-Shell Photoabsorption In Lanthanum, J.L. Dehmer, Anthony F. Starace
Potential-Barrier Effects In Photoabsorption. Iii. Application To 4D-Shell Photoabsorption In Lanthanum, J.L. Dehmer, Anthony F. Starace
Anthony F. Starace Publications
An exploratory calculation of the photoabsorption cross section near the 4d ionization threshold of lanthanum metal is carried out. The level structure of the configuration 4d94f is found to be altered by interaction with the continuum configuration 4d9εf. The Fano profile of the resonance above threshold is calculated, as are the oscillator strengths of the discrete states below threshold. Our results provide the ground work for more detailed calculations.
Elastic Scattering Of Low-Energy Electrons At 180° In Co2, Paul Burrow, L. Sanche
Elastic Scattering Of Low-Energy Electrons At 180° In Co2, Paul Burrow, L. Sanche
Paul Burrow Publications
A technique is described for the study of electrons which are elastically scattered from a gas target into a small solid angle centered at 180° with respect to the direction of the incident electron beam. The method is applied to electron scattering from CO2. Information is obtained concerning the nature of the compound state in the 4-eV region.
Raman-Active Resonance Modes, Overtones, And Anharmonicity In Nacl:Cu+, B.N. Ganguly, Roger D. Kirby, M.V. Klein, G.P. Montgomery Jr.
Raman-Active Resonance Modes, Overtones, And Anharmonicity In Nacl:Cu+, B.N. Ganguly, Roger D. Kirby, M.V. Klein, G.P. Montgomery Jr.
Roger Kirby Publications
The existence of an impurity-activated Eg resonance mode in NaCl:Cu+ has been suggested by several previous experiments. Raman data presented here reveal this resonance directly and also reveal the three components of the first overtone of the 23.5-cm-1 infrared resonance mode. The frequencies of the Eg resonance and the Eg component of the overtone are shifted as a result of a strong anharmonic coupling. Their line shapes and strengths are considerably altered by an interference between the Raman amplitudes. A reasonable fit to the data has been obtained using a simple theory.
Observation Of A Broad Resonance In The 23S Excitation Of Helium By Electron Impact, G. B. Crooks, R. D. Dubois, D. E. Golden, M. Eugene Rudd
Observation Of A Broad Resonance In The 23S Excitation Of Helium By Electron Impact, G. B. Crooks, R. D. Dubois, D. E. Golden, M. Eugene Rudd
M. Eugene Rudd Publications
We have observed a broad P-wave resonance at about 50 eV primary energy in the angular distribution of electrons scattered after excitation of the 23S state of helium. The resonance has a width of about 15 eV and affects the differential excitation cross section by more than 3 orders of magnitude. It is suggested that this resonance is associated with the temporary formation of triply excited states of the negative helium ion.
Strong, Quasiperiodic Dependence Of Autoionization Shape Parameters On Projectile Energy In H+ + He Collisions, F. D. Schowengerdt, M. Eugene Rudd
Strong, Quasiperiodic Dependence Of Autoionization Shape Parameters On Projectile Energy In H+ + He Collisions, F. D. Schowengerdt, M. Eugene Rudd
M. Eugene Rudd Publications
Profiles of the 2s2 (1S) autoionizing state in He have been observed in the ejected-electron spectrum of H+ + He for small angles of ejection and for H+ energies of 6 to 150 keV. The shape parameter q shows an increasing dependence on projectile energy as the angle of ejection is decreased, with strong, quasiperiodic oscillations appearing at 10°.
Detection Of Energetic Heavy Ions, Robert Katz, S. C. Sharma, Mehdi Homayoonfar
Detection Of Energetic Heavy Ions, Robert Katz, S. C. Sharma, Mehdi Homayoonfar
Robert Katz Publications
The delta-ray theory of track structure, applied earlier to such 1-or-more hit detection systems as the inactivation of dry enzymes and viruses, the NaI(Tl) scintillation counter, and nuclear emulsion, is extended to the silver activated phosphate glass dosimeter, the LiF thermoluminescent dosimeter, the creation of free radicals in solid biological substances, solid and liquid organic scintillators, and the ferrous sulfate (Fricke) dosimeter. The response of these systems to both gamma-rays and heavy ions is characterized by two parameters: 1) Dγ37, the dose of gamma-rays at which 37% of the sensitive elements remain unaffected by the radiation, and …