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Full-Text Articles in Physics
Hyperspherical Description Of Two-Electron Systems, Anthony F. Starace
Hyperspherical Description Of Two-Electron Systems, Anthony F. Starace
Anthony F. Starace Publications
While the use of hyperspherical coordinates to describe two-electron systems is quite old, it was Macek's introduction of a quasi-separable approximation in hyperspherical coordinates which made possible a host of theoretical studies elucidating the symmetries of doubly-excited states and the dynamics of processes involving two-electron atoms and ions. This work, up to about mid-1982, has been reviewed by Fano. However, much additional progress has been made since 1982, particularly on the symmetries of doubly excited electronic states, on the correspondences with molecular descriptions of two-electron systems, on the limitations of the quasi-separable approximation at small and at large distances, and …
The Calculation Of Photoionization Cross Sections, Anthony F. Starace
The Calculation Of Photoionization Cross Sections, Anthony F. Starace
Anthony F. Starace Publications
Photoionization is a sensitive probe of many-body and spin-dependent interactions. One can test our understanding of these interactions and the role they play in atomic dynamics by comparing the results of theoretical calculations with corresponding experimental measurements. One finds from such comparisons that our understanding of the photoionization process in atoms is excellent in many cases, imperfect in many others, and inadequate in still others. One finds in general also that the kinds of many-body and spin-dependent interactions included in a calculation is, in many cases, a more important consideration than the particular calculational method employed. In this brief report …
Granular Metal Films As Recording Media, Sy_Hwang Liou, C.L. Chien
Granular Metal Films As Recording Media, Sy_Hwang Liou, C.L. Chien
Sy-Hwang Liou Publications
High-density recording media require materials with a high magnetization and high coercivity as well as chemical stability, wear, and corrosion resistance. We explore the potential of granular metal films for recording media. Films of Fe granules about 150 Å in size embedded in an amorphous SiO2 matrix exhibit coercivities as high as 3 kOe at low temperatures and 1.1 kOe at room temperature, and magnetizations of about 150 emu/g. The methods with which these materials are fabricated, the essential microstructure characterization, and magnetic measurements are described.
Electronic Structure And Properties Of Sputtered Ta-Cu Films , K.D. Aylesworth, Sitaram Jaswal, M.A. Engelhardt, Z.R. Zhao, David J. Sellmyer
Electronic Structure And Properties Of Sputtered Ta-Cu Films , K.D. Aylesworth, Sitaram Jaswal, M.A. Engelhardt, Z.R. Zhao, David J. Sellmyer
David Sellmyer Publications
Films of TaxCu1-x have been produced in a co-sputtering system with dc- and rf-sputtering guns and a substrate attached to a rapidly rotating, water-cooled table. Samples were produced in the composition range 0.1≤x≤0.9. X-ray diffraction and electrical resistivity data between 4.2 and 300 K have been obtained. Diffraction measurements show that for 0.6≤x≤0.9 the samples are glassy. The room-temperature resistivities follow the Mooij correlation with a zero temperature coefficient of resistivity at a resistivity of 35 μΩ cm. The resistivity-versus-temperature data for Ta0.90Cu0.10 are compared to the extended Ziman-Faber theory …
Reply To Lung Cancer Risk From Rn In Chinese Study, Werner Hofmann, Robert Katz, Zhang Chunxiang
Reply To Lung Cancer Risk From Rn In Chinese Study, Werner Hofmann, Robert Katz, Zhang Chunxiang
Robert Katz Publications
We are writing in response to comments by V. A. Archer (Archer 1987) on our study of lung cancer incidence in two Chinese areas, designated as the high background and the control area (Hofmann et al. 1986). In his comments, he asserts that the epidemiological data suffer from two serious defects.
Versatile New Metalorganic Process For Preparing Superconducting Thin Films, M.E. Gross, M. Hong, Sy_Hwang Liou, P.K. Gallagher, J. Kwo
Versatile New Metalorganic Process For Preparing Superconducting Thin Films, M.E. Gross, M. Hong, Sy_Hwang Liou, P.K. Gallagher, J. Kwo
Sy-Hwang Liou Publications
A new technique for producing thin films of the high-temperature perovskite superconductors, LnBa2Cu3O7-x, where Ln represents a rare-earth element, using spin-on metalorganic precursors is described. Pyrolysis of the spin-coated films, consisting of mixed metal (2-ethyl hexanoates), leads to black films up to several microns thick whose degree of orientation is a function of the processing temperature and duration. Representative films of Y Ba2Cu3O7-x on MgO begin to exhibit orientation with the c axis perpendicular to the film plane at heat treatments above 900 °C. The superconducting behavior of a …
Molecular-Dynamics Simulation Of The Structural Phase Transition In Rb2Cacl4, D. P. Billesbach, P. J. Edwardson, John R. Hardy
Molecular-Dynamics Simulation Of The Structural Phase Transition In Rb2Cacl4, D. P. Billesbach, P. J. Edwardson, John R. Hardy
John R. Hardy Papers
We have simulated the structural phase transition of one member of A2BX4 layered perovskite-like compounds, Rb2CaC14. This family of compounds may be thought of as being constructed from normal perovskite unit cells but with a different stacking arrangement. In recent months, this structural family has become extremely important since it is the parent structure from which the new class of high-temperature superconductors comes from. The simulation was done using ab initio potentials with no adjustable parameters. Our calculations show a specific-heat anomaly at 400 K which corresponds to an observed pseudorotation of the …
The Rainbow And The Achromatic Telescope: Two Case Studies, M. Eugene Rudd
The Rainbow And The Achromatic Telescope: Two Case Studies, M. Eugene Rudd
M. Eugene Rudd Publications
From the history of science we can learn not only some science and some history, but also something about how science is done and how it interacts with technology.
The First case study chosen illustrates the development of an understanding of a phenomenon of nature-one that has been observed with awe and wonder for as long as man has walked the Earth, but has only been well understood in the last 200 years. Some of the greatest thinkers of all time have worked on the problems of the rainbow.
The second study shows how an important invention became possible only …
Radiobiological Modeling Based On Track Structure, Robert Katz
Radiobiological Modeling Based On Track Structure, Robert Katz
Robert Katz Publications
Since the interaction of beams of charged particles with targets in physics is customarily based on beam fluence and interaction cross section we have chosen the same logical structure for our radiobiological model.
Proceeding from simple to complex systems we have first constructed and verified a track structure model of observable tracks in nuclear emulsions, then of dry enzymes and viruses, of scintillation counters, of TLD’s, of the Fricke dosimeter as prerequisite to the construction of a valid radiobiological model.
For this model we require 1) knowledge of the average radial distribution of local dose about the path of an …