Showing papers in "Canadian Journal of Physics in 1995"
TL;DR: Octahedral media made of MgO-5%Cr2O3, with edge lengths of 18, 14, and 10 mm, were used as pressure cells in experiments in a multi-anvil solid media apparatus at pressures of 4 to 27 GPa and tempera...
Abstract: Octahedral media made of MgO–5%Cr2O3, with edge lengths of 18, 14, and 10 mm are used as pressure cells in experiments in a multi-anvil solid media apparatus at pressures of 4 to 27 GPa and tempera...
105 citations
TL;DR: In this paper, the pair-correlation function p(0) of an electron gas is derived by a partial-wave, phase-shift analysis, and the dependence of p( 0) on rs, the radius of the sphere (in Bohr units) containin
Abstract: The pair-correlation function p(0), at r = 0, of an electron gas is derived by a partial-wave, phase-shift analysis. The dependence of p(0) on rs, the radius of the sphere (in Bohr units) containin...
68 citations
TL;DR: The c-axis polarized phonon spectra of single crystals of YBa2Cu3O6+x, were measured for the doping range x 0 −05 −095, between 10 and 300 K.
Abstract: The c-axis polarized phonon spectra of single crystals of YBa2Cu3O6+x, were measured for the doping range x = 05 → 095, between 10 and 300 K The low background electronic conductivity, determine
61 citations
TL;DR: In this article, the sign determining energy derivative of the density of states at the Fermi energy, ∂N(eF)/∂e, in the expression for the Seebeck coefficient of Fe was found to be positive for liquid Fe at p below approximately 4.0 GPa but negative for p above 4.4 GPa.
Abstract: High p,T experiments provide indirect access to the deep interior of Earth. High p, T research at the University of Western Ontario using large volume cubic anvil presses has focused on in-situ measurements of physical properties of mantle and core related substances as they relate to Earth's interior physical processes. Thermoelectric power measurements of solid and liquid Fe, using twisted Fe/Pt–10%Rh junctions, have been made at p up to 6.4 GPa. By isolating the sign determining energy derivative of the density of states at the Fermi energy, ∂N(eF)/∂e, in the expression for the Seebeck coefficient of Fe, these measurements show that ∂N(eF)/∂e is positive for liquid Fe at p below approximately 4.0 GPa but ∂N(eF)/∂e is negative for p above 4.0 GPa. The solid phase polymorphism which Fe exhibits in this p region, and its influence on the liquid state, is suggested as the explanation for the short range bcc-like and fcc-like properties of the liquid. This finding corroborates our earlier measurements on th...
45 citations
TL;DR: In this paper, a new method of explicit description of n-dimensional polytopes generated by reflections of a single point (D-polytopes) or a face of maximal dimension (V-polytes) is presented.
Abstract: A new method of explicit description of n-dimensional polytopes generated by reflections of a single point (D-polytopes) or a face of maximal dimension (V-polytopes) is used to provide a comprehensive uniform description of all such polytopes in dimensions three and four. In addition a class of six-dimensional polytopes is also described; its symmetry group is the Weyl group of the simple Lie group D6.
40 citations
TL;DR: In this paper, high-resolution quasi-elastic incoherent neutron scattering studies of the translational dynamics of water molecules contained in the micropores of Vycor glass were carried out.
Abstract: The highlights of our recent high-resolution quasi-elastic incoherent neutron: scattering studies of the translational dynamics of water molecules contained in the micropores of Vycor glass and on ...
38 citations
TL;DR: In this article, the authors measured the energy distribution of neutrons scattered from polycrystalline C60 using a high-resolution filter-analyzer spectrometer, in the energy range 30 −90 µV (242 −726 cm−1).
Abstract: We measured the energy distribution of neutrons scattered from polycrystalline C60, using a high-resolution filter-analyzer spectrometer. In the energy range 30–90 meV (242–726 cm−1) we observed a ...
36 citations
TL;DR: In this paper, the authors describe the high strain rate constitutive behaviour of oxygen-free highconductivity (OFHC) and commercially pure copper and show considerable scatter in their measurements.
Abstract: Published measurements describing the high strain rate constitutive behaviour of oxygen-free high-conductivity (OFHC) and commercially pure copper are limited and show considerable scatter. To prov...
29 citations
TL;DR: In this paper, the potential surface with respect to the torsional angles of the methyl groups and the energy level structure was calculated by ab initio methods using extended basis sets.
Abstract: We have calculated the potential surface with respect to the torsional angles of the methyl groups, the torsional energy level structure, and the infrared and overtone Raman intensities by ab initio methods using extended basis sets. The conclusions that were drawn from a correlation to the observed spectra are the following, (i) The modest basis set MP2/6-31G(d, p) yields a value of 238.32 cm−1 for the v16 gearing mode in reasonable agreement with the observed value of 241.0 cm−1. Extension of the basis set to MP2/6-311G(df, p) marginally improves this value to 239.36 cm−1. A somewhat larger basis set, RHF/6-311+G(3df, 3p) was needed for a satisfactory description of the components of the polarizability and the dipole moment. (ii) The technique of full relaxation of the coordinates of the top and the frame was unable to account for the strong resonance between the 2v12 overtone gearing level and the v7 COC in-plane bending mode. (iii) The asymmetry along the diagonals of the potential surface that determ...
26 citations
TL;DR: The matrix elements of the polarizability anisotropy γ in the Raman spectra of diatomic molecules are investigated in this paper, where Gνν′(m) is the rotational factor with m −1.
Abstract: The matrix elements of the polarizability anisotropy γ in the Raman spectra of diatomic molecules are investigated. These matrix elements are given by where Gνν′(m) is the rotational factor with m ...
25 citations
TL;DR: The triple-axis spectrometer has been the instrument of choice for studies of dynamics, both magnetic and structural, in sing... as discussed by the authors, and has been used for inelastic neutron scattering.
Abstract: Since the pioneering work of Brockhouse on inelastic neutron scattering the triple-axis spectrometer has been the instrument of choice for studies of dynamics, both magnetic and structural, in sing...
TL;DR: The connections between information obtained in current research on fluid membranes using neutron scattering and nuclear magnetic resonance (NMR) are explored in two major chapters as discussed by the authors, with an emphasis on relationships between the time and distance scales intrinsic to neutron scattering, and NMR.
Abstract: After reviewing some of the basic measurements that characterize the study of physical properties of matter using neutron scattering and nuclear magnetic resonance (NMR), connections between information obtained in current research on fluid membranes using these two complementary techniques are explored in two major chapters. In the first, the type of information on the structure of fluid membranes obtained from coherent elastic neutron scattering is compared with that from NMR spectral characteristics. Then, the type of information obtained on dynamical properties from NMR relaxation (T1 and T2) measurements is compared with that from quasi-elastic neutron scattering. Examples of such connections are given with an emphasis on relationships between the time and distance scales intrinsic to neutron scattering and NMR.
TL;DR: In this paper, the authors classify the subalgebras of the symmetry algebra of fluid dynamics and magnetohydrodynamics equations into conjugacy classes under their respective groups.
Abstract: We classify the subalgebras of the symmetry algebras of fluid dynamics and magnetohydrodynamics equations into conjugacy classes under their respective groups. Both systems of equations are invariant under a Galilean-similitude algebra. In the case of the fluid dynamics equations, when the adiabatic exponent γ = 5/3, the symmetry algebra widens to a Galilean-projective algebra. We extend our previous classification of the symmetry algebra in the case of a nonstationary and isentropic flow to the general case of fluid dynamics and magnetohydrodynamics equations in (3 + 1) dimensions. The representatives of these algebras are given in normalized lists and presented in tables. Examples of invariant and partially invariant solutions, for both systems, are computed from representatives of these classifications. The final part of this work contains an analysis of this classification in connection with a further classification of the symmetry algebras in the case of the equations describing the flow of perfect g...
TL;DR: In this article, shadowgraphs were used to visualize local electrolyte concentration variations in quasi-two-dimensional electrochemical deposition experiments and the growth speed of the metal aggregate at the cathode is the same as the speed at which these flows move anions away from the cathodes, except at the earliest stages of growth.
Abstract: Using shadowgraphs, we visualize local electrolyte concentration variations in quasi-two-dimensional electrochemical deposition experiments. Experiments have been performed in both circular and parallel-electrode geometries. Our results indicate that a region of ion depletion moves from the cathode towards the anode, while a region of enhanced concentration grows in from the anode. Large-scale gravity-driven flows, which drive the growth of these regions, are observed. The growth speed of the metal aggregate at the cathode is the same as the speed at which these flows move anions away from the cathode, except at the earliest stages of growth. By integrating the shadowgraph intensity, we calculate the concentration field in the parallel geometry.
TL;DR: In this article, a variational trial function was used to determine an upper bound to the ground-state energy of the spiked harmonic-oscillator Hamiltonian, and a complementary energy lower bound was derived for all the discrete eigenvalues.
Abstract: A three-parameter variational trial function is used to determine an upper bound to the ground-state energy of the spiked harmonic-oscillator Hamiltonian . The entire parameter range λ > 0 and α ≥ 1 is treated in a single elementary formulation. The method of potential envelopes is also employed to derive a complementary energy lower bound formula valid for all the discrete eigenvalues.
TL;DR: In this article, the normalized phonon density of states g(v) of vanadium is accurately determined at room temperature (294 K) from the analysis of neutron inelastic-scattering data obtained using a triple-axis crystal spectrometer with a constant momentum transfer Q = 6.5
Abstract: The normalized phonon density of states g(v) of vanadium is accurately determined at room temperature (294 K) from the analysis of neutron inelastic-scattering data obtained using a triple-axis crystal spectrometer with a constant momentum transfer Q = 6.5 A−1, (1 A = 10−10 m) a constant scattered-neutron energy of 8.0 THz, and a variable incident-neutron energy. The energy transfer in the experiment varies from −1.9 to 10.0 THz, and the energy resolution (FWHM) is 0.35 THz at the elastic position. Necessary corrections are made for background scattering, multiple scattering, multiphonon scattering, absorption and self-shielding, and for the spatial inhomogeneity of the incident beam. The resulting g(v) distribution has an average statistical precision of about 3% and is characterized by peaks at 4.9 and 6.9 THz, which we attribute to transverse and longitudinal phonons, respectively, and by a cutoff at about 8.1 THz. The peaks in our g(v) distribution are much more clearly resolved than in any previous w...
TL;DR: In this article, a high-speed video camera, operating at 1000 frames per second, was used to determine crack velocities in concrete blocks subjected to impact loading, and the impact loads were generated using a large,...
Abstract: A high-speed video camera, operating at 1000 frames per second, was used to determine crack velocities in concrete blocks subjected to impact loading. The impact loads were generated using a large,...
TL;DR: For planar H2CS, (C2ν), the CS stretch potential curves were obtained for the four to six lowest singlet states of each symmetry species by using multireference CI methods.
Abstract: For planar H2CS, (C2ν), the CS stretch potential curves were obtained for the four to six lowest singlet states of each symmetry species by using multireference CI methods. Included were the (n, 4s), (n, 4p), (n, 3d), (π, 4s), and (π, 4p) Rydberg as well as the (n, π*), (π, π*), (σ, π*), (n, σ*), (n0, π*2), and (nπ, π*2) valence states. Vertical and adiabatic excitation energies, equilibrium CS distances, vibrational frequencies for the CS stretching mode, dipole moments, oscillator strengths, and Franck–Condon factors were evaluated and found to be in good agreement with known experimental data. The role of the 1(π, π*) state that diabatically crosses all 1A1 states, including the n2 ground-state configuration, causing many interactions with other states, has been given special attention. The following reassignments and predictions are of interest. (i) A switch of Ẽ and , with 1A1(n, 4py) corresponding to the Ẽ bands and 1B2(n, 4pz) corresponding to the bands is suggested, based on the energetic ordering...
TL;DR: In this article, it was shown that the closest approach of two O atoms, Rmin, is given by Rmin = 220 − 34.1n(s′) pm, where s′ is the number of s′ atoms.
Abstract: By examining which coordination numbers are not known for a large variety of cations, it is found that the closest approach of two O atoms, Rmin, is given by, Rmin = 220 – 34.1n(s′) pm, where s′ is...
TL;DR: The density functional theory originally developed by Hohenberg, Kohn, and Sham provides a rigorous conceptual framework for dealing with inhomogeneous interacting Fermi systems as discussed by the authors, and it can be used to deal with the problem of density functional analysis.
Abstract: The density functional theory originally developed by Hohenberg, Kohn, and Sham provides a rigorous conceptual framework for dealing with inhomogeneous interacting Fermi systems. We extend this app...
TL;DR: In this article, interrupted field time-of-flight (IFTOF) was applied to Cl-doped amorphous Se:Te and Se:As photoreceptor-type films to investigate the variation of the hole lifetime across the film due to sample inhomogeneities.
Abstract: The interrupted field time-of-flight (IFTOF) technique was applied to Cl-doped amorphous Se:Te and Se:As photoreceptor-type films to investigate the variation of the hole lifetime across the film due to sample inhomogeneities. By interrupting the hole photocurrent at different positions across the film, it was possible to obtain the variation of the hole lifetime, τ, across a photoreceptor film up to about two-thirds of the film thickness. For Cl-doped Se0.953Te0.047 films (46 at. ppm Cl) the Te content was uniform in the bulk, which resulted in the hole lifetime also being uniform. An important inference was that the Cl-content profile must therefore also be uniform. In the case of Cl-doped a-Se:0.2%As films (10 at. ppm Cl), the As concentration across the film was not uniform because of fractionation effects during vacuum deposition. The variation of the hole lifetime across the a-Se:As film correlated well with the As-concentration profile obtained from electron probe X-ray microanalysis. The present p...
TL;DR: In this paper, the authors describe a 50 MHz auroral radar system, named SAPPHIRE, which observes at two locations in Canada, namely, SAPE SOUTH and SAPE NORTH, at nominal cusp latitudes in the vicinity of the polar cap.
Abstract: This paper describes a new, 50 MHz auroral radar system, named SAPPHIRE, which observes at two locations in Canada: SAPPHIRE SOUTH, in the auroral zone and SAPPHIRE NORTH at nominal cusp latitudes in the vicinity of the polar cap – auroral zone boundary. SAPPHIRE was designed to offer superior time and frequency resolution for studies of the geophysical phenomena in the observing regions and to provide a better insight into the plasma processes responsible for the radio scattering. The radars are continuous-wave, dual bistatic systems with two transmitters and two receivers (both at a common receiver location) in each radar system. This configuration provides two-dimensional estimates of the phase velocities in the region of the scatterers. The systems were designed for unattended operation at remote sites and are controlled via modems using conventional telephone service. There are a number of innovative parts to the design of this radar. All frequencies used in the transmitter and receivers are generate...
TL;DR: In this article, the BRST formulation of the Christ-Lee model describing a particle moving in a central potential V, but being observed in a frame rotating with angular velocity ξ, is investigated.
Abstract: The BRST formulation of the Christ–Lee model describing a particle moving in a central potential V, but being observed in a frame rotating with angular velocity ξ, is investigated.
TL;DR: The Ampere force does not obey Newton's third principle, contrary to the Lorentz forces exerted by freely moving charges upon one another as mentioned in this paper, which is the opposite of the Amperes force.
Abstract: The Lorentz forces exerted by freely moving charges upon one another are not equal and opposite because the Lorentz force does not obey Newton's third principle, contrary to the Ampere force, which...
TL;DR: In this article, the electrodynamic equations in a rotating reference frame with velocities of rotation much less than the speed of light were derived for the cases of a medium stationary in the rotating frame, an...
Abstract: The electrodynamic equations in a rotating reference frame (with velocities of rotation much less than the speed of light) are derived for the cases of a medium stationary in the rotating frame, an...
TL;DR: In this article, the nonlinear instability of a horizontal interface separating two flowing superposed magnetic fluids of finite depths is described in the presence of a normal magnetic field and the stability of the system is discussed both theoretically and numerically.
Abstract: The nonlinear Kelvin–Helmholtz instability of a horizontal interface separating two flowing superposed magnetic fluids of finite depths is described in the presence of a normal magnetic field. The fluids are taken to be incompressible and inviscid and the motion is assumed to be irrotational. The method of multiple-scale perturbations is used to obtain two nonlinear Schrodinger equations describing the behaviour of the perturbed system. The stability of the system is discussed both theoretically and numerically and the stability diagrams are obtained. The nonlinear cutoff magnetic field that separates the regions of instability from those of stability is also obtained.
TL;DR: In this paper, the atmospheric electric field effect in the cosmic-ray muon component is discussed on the basis of the general theory of cosmic ray meteorological effects and the experimental results can be understood based on this theory.
Abstract: Experimental data on the atmospheric electric field effect in the cosmic-ray muon component are discussed on the basis of the general theory of cosmic-ray meteorological effects. In this framework, we develop the theory of atmospheric electric field effects in the hard- and soft-muons of secondary cosmic rays and in the neutron-monitor counting rates as well. We show that the experimental results can be understood on the basis of this theory. We also show that a sufficient atmospheric electric field effect in the cosmic-ray neutron component is to be expected because the neutron monitors work as analyzers of soft muons and really detect only negative muons as well as neutrons.
TL;DR: The temperature dependence of neutron diffraction by Ca 0.4K 0.6(NO3)1.4, in the liquid and glassy states, was measured together with the time dependence of the transformation to the crystalline stat...
Abstract: The temperature dependence of neutron diffraction by Ca0.4K0.6(NO3)1.4, in the liquid and glassy states, was measured together with the time dependence of the transformation to the crystalline stat...
TL;DR: In this article, a complete system for the production of the fullerides C60 and C70 is described, where emphasis is placed on efficient, continuous production of high-quality materials, and a chromotography column is cycled continuously.
Abstract: A complete system for the production of the fullerides C60 and C70 is described. Emphasis is placed on efficient, continuous production of high-quality materials. Carbon soot with a content of 2–5% of a mixture of C60 and C70 is prepared from carbon rods with an arc furnace. The mixture is separated from the carbon by using a Soxhlet extractor. The C60 and C70 are separated with a chromotography column in which the solvent is cycled continuously. The separated C60 is purified by sublimation. The C70 is separated from heavier fullerides with a second chromotography procedure. Single crystals of C60 are prepared from pure C60 powder by slow sublimation. The C60 is characterized by mass spectroscopy, X-ray diffraction, and Raman and infrared spectroscopy. Typical data obtained with these techniques are shown.
TL;DR: In this paper, the hyperfine and isotope shifts of the (6s)21S0/0/1P1 transition in barium were measured using a ring dye laser to excite an atomic beam.
Abstract: The hyperfine and isotope shifts of the (6s)21S0 → (6s6p) 1P1 transition in barium were measured using a ring dye laser to excite an atomic beam. The laser frequency was scanned across the transiti...