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Full-Text Articles in Physics
Detection Of Vibrationally Excited N2 By Superelastic Electron Impact, Paul Burrow, Paul Davidovits
Detection Of Vibrationally Excited N2 By Superelastic Electron Impact, Paul Burrow, Paul Davidovits
Paul Burrow Publications
We have observed electrons scattered superelastically from nitrogen molecules vibrationally excited by quenching collisions with optically excited rubidium atoms. Analysis of the energy gained by the electrons shows that in more than 10% of the quenching collisions the highest energetically allowed vibrational state of N2, v=5, is populated. The relative superelastic cross section for collisions between molecules in this state and electrons is measured and compared with that predicted by detailed balance.
Ionic Transport In Potassium Chloride, Robert Fuller, Charles L. Marquardt, Michael H. Reilly, John C. Wells Jr.
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 …
Energy Deposition By Electron Beams And Δ Rays, E. J. Kobetich, Robert Katz
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.
Application Of The Method Of Lattice Statics To Interstitial Cu Atoms In Cu, John Flocken, John Hardy
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 …
Infrared Absorption Properties Of Lih, Lid Mixed Crystals, Sitaram S. Jaswal, John R. Hardy
Infrared Absorption Properties Of Lih, Lid Mixed Crystals, Sitaram S. Jaswal, John R. Hardy
John R. Hardy Papers
The normal modes of pure LiH and LiD, required in impurity mode calculations, have been computed on the basis of the deformation-dipole model. Neutron-scattering results of Verble, Warren, and Yarnell for Li7D, along with some other experimental quantities, have been used to determine the various parameters involved. It is found that the frequency spectrum of LiH has a gap and that a substitutional D- ion produces a local mode in this gap whose frequency has been computed, together with its amplitude at the impurity. The infrared absorption frequency associated with this local mode and its integrated absorption …
Formation Of Etchable Tracks In Dielectrics, Robert Katz, E. J. Kobetich
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 …
Response Of Nai(T1) To Energetic Heavy Ions, Robert Katz, E. J. Kobetich
Response Of Nai(T1) To Energetic Heavy Ions, Robert Katz, E. J. Kobetich
Robert Katz Publications
Experimental values of the relative heights of scintillation pulses generated in NaI(T1) crystals, by heavy ions (Z>5) of energy 1-10 MeV/amu, agree well with computed relative cross sections for photon production, from a theory based on the assumption of a one-hit response to the spatially distributed dose of ionization energy, and a characteristic dose of 4x107 erg/cm3 for this material Discrepancies between theory and experiment for He bombardments arise from the theoretical neglect of the nonlinear dose variation over the sensitive volume surrounding each TI atom. Similar discrepancies arising from the neglect of molecular volume occur …
Width Of Heavy-Ion Tracks In Emulsion, E. J. Kobetich, Robert Katz
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.
Possible Trivacancy Contribution To Ionic Conductivity, Robert Fuller, M.H. Reilly
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 …
Lattice Dynamics And Second-Order Raman Spectrum Of Csf, John R. Hardy, Arnold Karo
Lattice Dynamics And Second-Order Raman Spectrum Of Csf, John R. Hardy, Arnold Karo
John R. Hardy Papers
Results are presented for a precise calculation, based on the deformation dipole model with short-range repulsive interactions between second-neighbor negative ions, of the normal-mode frequency distribution of CsF. The extreme properties of this crystal are reflected in the unusual appearance of the distribution. From these results, we can also predict the form of the second-order Raman spectrum of CsF for two alternative assumptions regarding the Raman polarizability tensor. Both spectra are unusual in that they consist almost entirely of very sharp, clearly separated lines. Furthermore, the spectra corresponding to these two assumptions are very different and should be easily distinguishable …
Far Infrared Properties Of Lattice Resonant Modes. I. Isotope Shifts, Roger D. Kirby, I.G. Nolt, R.W. Alexander Jr., A.J. Sievers
Far Infrared Properties Of Lattice Resonant Modes. I. Isotope Shifts, Roger D. Kirby, I.G. Nolt, R.W. Alexander Jr., A.J. Sievers
Roger Kirby Publications
The frequency shift of a lattice resonant mode associated with the isotopic substitution of an impurity ion has been measured for NaCl: Cu+, KI: Ag+, and KBr: Li+. For all three systems, the experimental frequency shifts can be described satisfactorily by an Einstein oscillator representation for the resonant mode with the oscillator mass set equal to the impurity-ion mass. The model of Benedek and Nardelli and also Klein does not account for the experimental results of NaCl: Cu+ or KBr: Li+. The inclusion of anharmonic forces does improve the agreement between …
Electrical Conductivity Of Potassium Chloride, Robert Fuller, Michael H. Reilly, Charles L. Marquardt, John C. Wells
Electrical Conductivity Of Potassium Chloride, Robert Fuller, Michael H. Reilly, Charles L. Marquardt, John C. Wells
Robert G. Fuller Publications
The electrical conductivity of potassium chloride is discussed within the framework of a four-defect model of the crystal. The four defects are mobile anion and cation vacancies and immobile divalent cation impurities and divalent cation impurity-cation vacancy complexes. The Teltow formulation of the four-defect mode1 fails to describe precisely the measured electrical conductivity of KCl over the entire intrinsic and extrinsic range.
Projected Hartree Product Wavefunctions, Gordon A. Gallup
Projected Hartree Product Wavefunctions, Gordon A. Gallup
Gordon Gallup Publications
A method for performing a restricted configuration interaction calculation on atoms or molecules based on the use of Young operators from the symmetric groups is discussed and its relation to some other types of calculations is pointed out. The method in its most general form can be said to be an extension of the independent particle approach which represents the wavefunction in terms of the n best possible one-particle orbitals for the n-particle system. Illustrations are given for the hydrogen molecule, the helium atom, and the allyl radical. ©1968 American Institute of Physics
Excitation Of Auto-Ionizing Levels In Neon By Ion Impact, A. K. Edwards, M. Eugene Rudd
Excitation Of Auto-Ionizing Levels In Neon By Ion Impact, A. K. Edwards, M. Eugene Rudd
M. Eugene Rudd Publications
Auto-ionizing states of neutral and singly ionized neon were produced by bombarding neon gas with H+, He+, and Ne+ ions in the 150-250-keV energy range. Sixty lines in the electron spectrum were found, of which 43 have been classified into 13 Rydberg series. Ten of these series were previously unreported. Auger electrons from one- and two-vacancy states are also reported. Relative intensities of all transitions are listed.
Optimum Spacing Of Square And Circular Coil Pairs, M. Eugene Rudd, J. R. Craig
Optimum Spacing Of Square And Circular Coil Pairs, M. Eugene Rudd, J. R. Craig
M. Eugene Rudd Publications
In a previous note Crownfield pointed out that the magnetic field along the axis of a coil pair is within a prescribed uniformity over a substantially longer region than that given by the Helmholtz spacing if a somewhat larger spacing is used. In the note, values of coil spacing and length of uniform field region are given for a few desired uniformities, but only for a particular "thick" coil pair, i.e., one with cross-sectional dimensions comparable to the spacing. Many coil pairs, such as those used to annul the earth's field over the region occupied by some apparatus, have cross-sectional …
Energy Spectra Of Auto-Ionizing Electrons In Oxygen, M. Eugene Rudd, Kenneth Smith
Energy Spectra Of Auto-Ionizing Electrons In Oxygen, M. Eugene Rudd, Kenneth Smith
M. Eugene Rudd Publications
Experimental and theoretical data are presented showing the energy spectra of auto-ionizing electrons from atomic oxygen. The experimental data were obtained by bombarding oxygen gas with 100-keV H+ and He+ ions; the theoretical results were obtained in a close-coupling calculation which coupled the 4S, 2D, and 2P terms of the ground-state configuration of O+ in electron-O+ scattering.