Showing papers in "Canadian Journal of Physics in 1993"
TL;DR: Lifetimes have been measured for 14 levels belonging to the z4P0, z4D0 and z6P0 terms of CrII using laser-induced fluorescence of a fast beam.
Abstract: Lifetimes have been measured for 14 levels belonging to the z4P0, z4D0, z6P0, z6D0, and z6F0 terms of CrII using laser-induced fluorescence of a fast beam. The results are compared with earlier LIF...
29 citations
TL;DR: In this paper, a collection of 10,866 ground-state (X1Σ+) vibration and pure rotational line positions of four carbon monoxide isptopomers (12C16O, 12C18O, 13C 16O, and 13C 18O) is employed simultaneously in a direct determination of the radial Hamiltonian operator in compact analytical form.
Abstract: A collection of 10 866 of the most precise ground-state (X1Σ+) vibration–rotational and pure rotational line positions of four carbon monoxide isptopomers (12C16O, 12C18O, 13C16O, and 13C18O) is employed simultaneously in a direct determination of the radial Hamiltonian operator in compact analytical form. The 22-parameter isotopically self-consistent operator takes full account of the Born–Oppenheimer breakdown and its quantum-mechanical eigenvalues represent all the available spectroscopic line positions of CO isotopomers to within the experimental uncertainties. Rayleigh–Schrodinger perturbation theory is employed to calculate quantum-mechanical molecular constants of rotation (Bν – Mν) for nine common isotopomeric forms of CO. Together with the quantum-mechanical vibrational eigenvalues these are fully consistent with the exact eigenvalues obtained by direct solution of the radial wave equation. The set of constants is expected to provide an accurate prediction of line positions of CO isotopomers that...
28 citations
TL;DR: In this article, the excitation functions of 51V (α, xn), x = 1.3, p3n, α, α3n) and 59Co [(α, 2n), αxn); x'= 1, 2] reactions were measured up to 50'MeV by the stacked-foil activation technique and high-resolution Ce(Li)-HPGe spectroscopy method.
Abstract: The excitation functions of 51V [(α, xn), x = 1.3; (α, p3n); (α, α3n) (α, 2α)] and 59Co[(α, 2n); (α, αxn); x = 1, 2] reactions were measured up to 50 MeV by the stacked-foil activation technique and high-resolution Ce(Li)–HPGe spectroscopy method. Of these 51V(α, xnypzα) reactions were studied for the first time with better accuracy than earlier measurements, which were done with a poor resolution scintillation–Ge(Li) detectors some 20 years ago. In the case of 59Co, existing data show large discrepancies at low energy. Comparisons are presented with the prediction of hybrid and exciton models. While for the (α, xn) type of reactions, reasonably explainable pre-equilibrium contributions are found, there seem to be indications of direct inelastic scattering effects in the (α, αxn) type of reactions.
23 citations
TL;DR: In this article, the authors investigated the possibility of using satellite airglow limb tomography to study spatial structures in the air glow emissions of the upper mesosphere and lower thermosphere.
Abstract: In this paper, we investigate the possibility of using satellite airglow limb tomography to study spatial structures in the airglow emissions of the upper mesosphere and lower thermosphere We describe inversion procedures for converting satellite airglow limb observations into two-dimensional distributions of volume emission rates The performance of the inversion procedures is assessed using simulated limb observations and we demonstrate the potential of this tomographic technique for studying the horizontal and vertical characteristics of wave-driven disturbances in the 80–100 km region
21 citations
TL;DR: In this article, the motion of an incompressible flow of an electrically conducting viscoelastic fluid past an infinite porous flat plate subject to uniform suction in the presence of a transverse uniform magnetic field was studied.
Abstract: In this work we study the motion of a two-dimensional incompressible flow of an electrically conducting viscoelastic fluid past an infinite porous flat plate subject to uniform suction in the presence of a transverse uniform magnetic field. The effects of the flow on the temperature of the plate are studied when the plate is thermally insulated, and when it is kept at a constant temperature that is higher than that of the free stream. A method proposed by Lighthill and Stuart is utilized in solving the problem. The effects of various parameters such as the magnetic number, the viscoelastic parameter, and the frequency of the free-stream oscillations on the flow are studied.
19 citations
TL;DR: In this article, the optical properties of planar waveguides made of metal ion doped polymer thin films were measured by the prism-film coupler (PFC) method for the first time.
Abstract: Cr(VI) and Fe(III) doped polyvinyl alcohol) and poly(acrylic acid) polymers have been used as real-time holographic recording media as well as materials to fabricate planar waveguides. Planar wave guides were made of these metal ion doped polymer thin films. Changes in the absorption spectra of these polymer films due to irradiation with an intense illumination of 468 nm light were observed. Modifications in optical properties of dichromated poly(vinyl alcohol) (DCPVA), dichromated poly(acrylic acid) (DCPAA), and ferric chloride doped polyvinyl alcohol) (FePVA) were experimentally determined by the prism–film coupler (PFC) method for the first time. Changes in the refractive index at 632.8 nm were monitored for different exposure energies. Modification of the modal properties was observed and the refractive index of these films was also determined from the angular position of the guided modes. Optical losses in both exposed and unexposed films of DCPVA, DCPAA, and FePVA were measured employing a coupling ...
18 citations
TL;DR: In this article, a cubic perovskite structure with an estimated 2.9% of a minor pyrochlore phase of Pb(Ni1/3,Nb2/3)O3 was synthesized by a high-temperature solid-state reaction technique.
Abstract: Polycrystalline samples of a cubic perovskite structure with an estimated 2.9% of a minor pyrochlore phase of Pb(Ni1/3,Nb2/3)O3 were synthesized by a high-temperature solid-state reaction technique. Dielectric studies show that the material is a good relaxor with a high dielectric constant. Diffuse phase transition through a wide Curie-temperature range was observed. The activation energy in a specified range of temperature for the material is estimated.
13 citations
TL;DR: In this paper, the time-resolved EUV spectra of foil-excited 9.5 MeV Mo ions were recorded in the wavelength range of the ground state Δn ∆ = 0 intercombination lines in Zn I-, Ga I-, and Ge I-like spectra.
Abstract: Time-resolved EUV spectra of foil-excited 9.5 MeV Mo ions were recorded in the wavelength range of the ground state Δn = 0 intercombination lines in Zn I-, Ga I-, and Ge I-like spectra. Decay curves were obtained and analyzed; the results are compared with those of calculations.
13 citations
TL;DR: In this article, the noncollinear reflected second-harmonic generation (SHG) for monolayers of Rhodamine 6G adsorbed on fused silica was investigated.
Abstract: We investigate the noncollinear reflected second-harmonic generation (SHG) for monolayers of Rhodamine 6G adsorbed on fused silica. We show that the ratios between the surface molecular χ(2) components can be related to the values of the polarization angles of the two incident beams when minima of the resulting SHG intensity are obtained.
13 citations
TL;DR: In this paper, a significant narrowing of the longitudinal-mode spectrum of continuous-wave visible gain-guided diode laser was achieved by using an external cavity bounded by a phase conjugate mirror.
Abstract: A significant narrowing of the longitudinal-mode spectrum of continuous-wave visible gain-guided diode lasers was achieved by using an external cavity bounded by a phase conjugate mirror. Longitudinal-mode discrimination was further improved by inserting a thin etalon in the external cavity. With this technique, the coherence length of the laser beam has been increased by a factor of 4 and the emission wavelength was tunable over a range of 1.4 nm, at constant temperature.
13 citations
TL;DR: In this article, the damping rate of a moving fermion in a hot plasma was evaluated within an improved one-loop order, in which the hard-thermal loop corrections were taken into account.
Abstract: We point out the difficulties and ambiguities in evaluating the damping rate of a moving fermion in a hot plasma, within an improved one-loop order, in which the hard-thermal loop corrections are taken into account.
TL;DR: In this article, the authors present the effective Lagrangians that summarize collective effects in ultrarelativistic quark-gluon and electron-photon plasmas.
Abstract: The solution of the plasmon problem and the subsequent development of an effective field-theory approach to ultrarelativistic plasmas are reviewed. The effective Lagrangians that summarize collective effects in ultrarelativistic quark–gluon and electron–photon plasmas are presented. A generalization that describes an electromagnetic plasma at all temperatures and densities is proposed.
TL;DR: In this paper, the index of refraction and the absorption in lattice-matched InGaAsP/InP-based photonic devices are modeled over an extended practical wavelength range.
Abstract: Methods for modeling, over an extended practical wavelength range, the index of refraction and the absorption in lattice-matched InGaAsP/InP-based photonic devices are reviewed, completed, and clarified. Carrier-induced effects on the optical properties are given special attention. For the index of refraction, the method gives results within 1% of the experimental ones. On the other hand, the results for absorption are more difficult to compare owing to the lack of experimental data.
TL;DR: In this article, the effective action found by Braaten and Pisarski, and by Frenkel, Taylor, and Wong that summarizes all hard thermal loops is investigated, and nonlocal field equations for ψ and Aμ are derived.
Abstract: The effective action found by Braaten and Pisarski, and by Frenkel, Taylor, and Wong that summarizes all hard thermal loops is investigated. Nonlocal field equations for ψ and Aμ are derived. Nonlocal forms are constructed for the U(1)-vector and axial-vector currents, the SU(N)-vector and axial-vector currents, the energy-momentum tensor, and the angular momentum density.
TL;DR: In this article, the renormalized hypervirial perturbation method was used to compute the energy levels for a double-well potential V(x) = Z2x2
Abstract: The renormalized hypervirial perturbation method is used to compute the energy levels for a double-well potential V(x) = −Z2x2 + x2J. Results are produced for a wide range of parameters and of state numbers . Comparison is made with results obtained by other means.
TL;DR: Sputtering yields of cobalt and chromium by argon and xenon ions with energies below 50 eV were reported in this paper, where the targets were electroplated on copper substrates.
Abstract: Sputtering yields of cobalt and chromium by argon and xenon ions with energies below 50 eV are reported. The targets were electroplated on copper substrates. Measurable sputtering yields were obtai...
TL;DR: Although the optical parametric oscillator (OPO) is more than 25 years old, it has not seen widespread use unlike other tunable sources such as the dye laser.
Abstract: Although the optical parametric oscillator (OPO) is more than 25 years old, it has not seen widespread use unlike other tunable sources such as the dye laser. Part of the reason for this is the low...
TL;DR: In this paper, the WKB approximation was applied to the rotating Morse oscillator for the ground state of the H2 molecule and was compared with those obtained by several other methods.
Abstract: The WKB approximation is applied to the rotating Morse oscillator. Results are presented for the ground state of the H2 molecule and are compared with those obtained by several other methods. The WKB method gives the best results for v > 5. At smaller values of v, the WKB results are only slightly less accurate than the best ones.
TL;DR: In this paper, the authors derived relativistic three-particle wave equations for scalar particles,, and, interacting via a massive or massless scalar field, χ.
Abstract: We derive relativistic three-particle wave equations for scalar particles , , and , interacting via a massive or massless scalar field, χ. The variational method, within the Hamiltonian formalism of quantum field theory, is used to obtain the equations using a simple Ansatz. Approximate solutions of these equations are presented for various strengths of the coupling. The magnitude of the relativistic effects in the three-particle energies and wave functions is illustrated by comparison with nonrelativistic results.
TL;DR: In this paper, two new techniques for the approximate calculation of the eigenvalues of the Schrodinger equation were proposed, which are variants of the method of self-similar approximations suggested recently by one of the authors.
Abstract: We study two new techniques for the approximate calculation of the eigenvalues of the Schrodinger equation. These techniques are variants of the method of self-similar approximations suggested recently by one of the authors. We illustrate the ideas by an anharmonic oscillator problem. We show that the precision of the method can be very high. For example, the ground-state energy of an anharmonic oscillator can be calculated with an error not exceeding 0.07% for all anharmonicity parameters ranging from zero to infinity.
TL;DR: In this article, the authors discuss the effective action that generates the hard thermal loops used in the resummation program of Braaten and Pisarski, and discuss aspects of the effective actions used to generate the thermal loops.
Abstract: We discuss aspects of the effective action that generates the "hard thermal loops" used in the resummation programme of Braaten and Pisarski.
TL;DR: In this article, a new method has been developed to measure the excited state absorption cross sections σ1n, of highly fluorescent dyes, which gives excited singlet-state absorption (ESSA) spectra over most of the...
Abstract: A new method has been developed to measure the excited-state absorption cross sections σ1n, of highly fluorescent dyes. which gives excited singlet-state absorption (ESSA) spectra over most of the ...
TL;DR: In this paper, experimental differential cross sections for inelastic scattering of electrons from helium atoms in the presence of an intense (~108 W cm−2) carbon dioxide laser were obtained.
Abstract: We report experimental differential cross sections for inelastic scattering of electrons from helium atoms in the presence of an intense (~108 W cm−2) carbon dioxide laser. The cross sections for excitation of the 21P state of helium with the simultaneous absorption or emission of one laser quantum were measured over the incident electron energy range of 36–70 eV and scattering angles of 13–31°.
TL;DR: In this paper, the authors compared the Stark-shifted lines (caused by negative charges, Q 1− of H2 and D2 in the same sample and showed that the mechanisms giving rise to charge-induced effects are somewhat more complicated than previously thought.
Abstract: Proton-beam irradiation of mixtures of solid hydrogens, specifically H2 in D2 and H2 in HD, were studied using infrared absorption spectroscopy. Mixture ratios from 5–50% H2 in D2 near 4.2 K represent the ratios of most interest. This study allows direct comparison of the Stark-shifted lines (caused by negative charges, Q1− of H2and D2 in the same sample. These lines occur in different spectral regions but were thought to have a common cause. Analysis of spectral intensities, as well as timing behaviour as the proton beam is turned off, indicates that the mechanisms giving rise to charge-induced effects are somewhat more complicated than previously thought.
TL;DR: In this article, a convenient series representation for the real part of the Lagrangian density of quantum electrodynamics for arbitrary nonvanishing electric fields, E, and magnetic fields, B, has been provided by Mielniczuk.
Abstract: A convenient series representation for the real part of the Heisenberg–Euler Lagrangian density of quantum electrodynamics for arbitrary nonvanishing electric fields, E, and magnetic fields, B, has been previously provided by Mielniczuk. Using this representation, numerical information for the Lagrangian is presented for the range and (subscript cr stands for critical) with the electric and magnetic fields parallel and Ecr ≈ 1.7 × 1016 V cm−1 and Bcr ≈ 4.4 × 1013 G. It was found that for a fixed electric field, the Lagrangian is monotonically increasing with increasing magnetic field strength. However, for a fixed magnetic field, the Lagrangian exhibits a positively valued maximum before turning monotonically decreasing with increasing electric field strength. Further, the series representation is extended to the case of vanishing electric or magnetic field. Numerical results for these special cases are in very close agreement with previous results, which indicated a maximum value for the Lagrangian densi...
TL;DR: In this article, the 400nm luminescence band of germanium-doped-silica optical fibres was excited via two-photon absorption of an argon ion laser beam.
Abstract: The 400 nm luminescence band of germanium-doped-silica optical fibres was excited via two-photon absorption of an argon ion laser beam. It was observed that the photoluminescence decreased by as much as 25% during the exposure of the fibres to several hundred milliwatts of optical power fora few hours. Surprisingly, the amount of bleaching is not a given proportion of the initial intensity of the luminescence band. These luminescence measurements are qualitatively related to the photosensitivity of the optical fibres. The saturation of two-photon absorption at relatively low power is also observed.
TL;DR: In this article, three subjects in thermal field theory are discussed; why in SU(N) gauge theories the Z(n) symmetry is broken at high temperature, the possible singularity structure of gauge-variant propagators, and the problem of how to compute the viscosity from the Kubo formula.
Abstract: Three subjects in thermal field theory are discussed; why in SU(N) gauge theories the Z(N) symmetry is broken at high (instead of low) temperature, the possible singularity structure of gauge-variant propagators, and the problem of how to compute the viscosity from the Kubo formula.
TL;DR: The Dirac Hamiltonian with an external Coulomb field was considered in this paper, where an even part that conserves the number of fermion-antifeimion pairs and an odd part that permits pair a...
Abstract: The Dirac Hamiltonian with an external Coulomb field is considered in Fock space; it contains an even part that conserves the number of fermion–antifeimion pairs and an odd part that permits pair a...
TL;DR: The perturbative Ward identities obeyed by the effective vertices and propagators for thermal quantum chromodynamics (QCD) have recently been used to prove to order g2T the on-shell transversality as mentioned in this paper.
Abstract: The perturbative Ward identities obeyed by the effective vertices and propagators for thermal quantum chromodynamics (QCD) have recently been used to prove to order g2T the on-shell transversality ...
TL;DR: In this article, the imaging performance of zero-thickness substrate planar kinoform lenses designed for infinite conjugate-imaging is not affected when a plane parallel plate, placed in the object space, is used a...
Abstract: The imaging performance of zero-thickness substrate planar kinoform lenses designed for infinite conjugate-imaging is not affected when a plane parallel plate, placed in the object space, is used a...