Showing papers in "Canadian Journal of Physics in 1971"
TL;DR: In this article, the scattering of neutrons by liquid helium has been studied over a wide range of wave-vector transfers, including 0.2 ǫ −1, 0.9 Á−1, and energy transfers.
Abstract: The scattering of neutrons by liquid helium has been studied over a wide range of wave-vector transfers, 0.2 < Q < 9.0 A−1, and energy transfers . The measurements were performed with both a time-o...
298 citations
TL;DR: In this paper, the behavior of the screw dislocation core in the presence of an external shear stress was examined for the body-centered cubic and hexagonal close-packed phases of a model sodium lattice.
Abstract: The behavior of the screw dislocation core in the presence of an external shear stress has been examined for the body-centered cubic and hexagonal close-packed phases of a model sodium lattice, usi...
227 citations
TL;DR: Using inelastic neutron scattering, the frequency and wave vector dispersion relations for the lattice vibrations in a single crystal of palladium have been determined at 120, 296, 673, and 853 °K.
Abstract: Using inelastic neutron scattering, the frequency – wave vector dispersion relations for the lattice vibrations in a single crystal of palladium have been determined at 120, 296, 673, and 853 °K. A...
178 citations
TL;DR: In this paper, the rotational line strengths for 3Σ±−3 Σ± electric dipole transitions were calculated for nonzero values of the splitting constant λ.
Abstract: Rotational line strengths (Honl–London factors) are calculated for 3Σ±–3Σ± electric dipole transitions, allowing for nonzero values of the splitting constant λ. If the 3Σ states are intermediate between Hund's coupling cases (a) and (b) only one transition moment is required, whereas if there is a tendency to case (c) four transition moments may be required. The resulting formulas are compared with the observed spectra of the diatomic molecules of the Group VI elements. The same formulas are valid for 3Σ±–3Σ± magnetic dipole transitions.
114 citations
TL;DR: In this paper, the 4875 cm−1 band of glyoxal has been photographed in absorption under high resolution and a rotational analysis carried out, which is consistent with the assignment of the band to an allowed 1B1-1A1 (π*n) transition of cis glyoxalin.
Abstract: The 4875 A band of glyoxal has been photographed in absorption under high resolution and a rotational analysis carried out. The band is of type C and the principal molecular constants are: A′ = 0.9069 cm−1, B′ = 0.1983 cm−1, C′ = 0.1627 cm−1, A″ = 0.8910 cm−1, B″ = 0.2066 cm−1, C″ = 0.1681 cm−1, v0 = 20 507.57 cm−1. The A-rotational constants are smaller by a factor of ~2 than the constants found earlier for trans glyoxal. The new results are consistent with the assignment of the band to an allowed 1B1–1A1 (π*–n) transition of cis glyoxal. Temperature studies indicate that the cis isomer lies 1125 ± 100 cm−1 above the trans isomer. This is the first time that cis glyoxal has been detected experimentally.
112 citations
TL;DR: In this article, a rotational analysis of the 000-000 band near 8580 A shows conclusively that the electronic transition is. From molecular orbital considerations the lower state is assigned as.
Abstract: The transient absorption spectrum observed previously (Devillers) in the flash photolysis of carbon suboxide has been studied under high resolution in the region 5000 to 9000 A and assigned to the CCO radical. A rotational analysis of the 000–000 band near 8580 A shows conclusively that the electronic transition is . From molecular orbital considerations the lower state is assigned as . Short progressions involving the stretching vibrations (ν1′ = 0–3, ν3′ = 0–1) have been observed. A Fermi resonance has been found involving ν3′ and 2ν2′. Some sequence bands have been assigned; in particular the 010–010 sequence band clearly shows the Renner splittings expected for the A3Πi excited state. A band with a different type of rotational structure has been assigned to the forbidden component 010 3Σ(−) – 000 3Σ−. The rotational analysis of this band is in excellent agreement with the theory of Hougen for the rotational energy levels of a linear molecule in the ν2 = 1 level of a 3Π state.The following molecular co...
94 citations
TL;DR: In this article, room temperature electroreflectance measurements have been made on samples of AlxGa1−xAs alloys, grown by liquid epitaxy, and the variation of the different band transition energies, E0, E1, E2, etc.
Abstract: Room temperature electroreflectance measurements have been made on samples of AlxGa1−xAs alloys, grown by liquid epitaxy. The variation of the different band transition energies, E0, E1, E2, etc. h...
81 citations
TL;DR: In this article, the two components of the (ν1, 2ν2) Fermi doublet of gaseous CO2 in an absorption path length of 56m at 192 °K were analyzed.
Abstract: The two components of the (ν1, 2ν2) Fermi doublet of gaseous CO2 in an absorption path length of 56 m at 192 °K show a complex structure. When the allowed C16O18O absorption and the pressure-induce...
77 citations
TL;DR: In this paper, the Raman spectrum of an oriented single crystal of CaSO4∙2H2O has been recorded from 20 to 3600 cm−1 at 300 °K and 77 °K using polarized laser excitation.
Abstract: The Raman spectrum of an oriented single crystal of CaSO4∙2H2O has been recorded from 20 to 3600 cm−1 at 300 °K and 77 °K using polarized laser excitation. The symmetries of the observed Raman line...
58 citations
TL;DR: In this paper, the Fermi surface neck size and the scattering cross sections for the neck and belly orbits have been measured in dilute alloys of Zn, Al, Ge, Si, Ni, Co, Fe, Mn, and Cr in Cu.
Abstract: The Fermi surface neck size and the scattering cross sections for the neck and belly orbits have been measured in dilute alloys of Zn, Al, Ge, Si, Ni, Co, Fe, Mn, and Cr in Cu. Earlier observations of rigid-band behavior for the neck size in Cu(Zn) and Cu(Al), while essentially substantiated by the present measurements, are now believed to be fortuitous; Cu(Ge) and Cu(Si) do not agree with a rigid-band prediction. The changes (generally reductions) of neck size in the transition metal alloys do not appear to be related directly to changes of electron concentration. The scattering anisotropy is rather small in the heterovalent alloys, the scattering being somewhat greater on the necks, but is large and in the opposite sense in the transition metal alloys. The magnitude and anisotropy of scattering is interpreted in terms of phase shifts associated with the impurities and the wave functions over the Fermi surface. There is evidence for additional scattering anisotropy in alloys exhibiting the Kondo effect.
55 citations
TL;DR: In this article, the convergence of the reference spectrum series for the G matrix is investigated, as well as the approximation of choosing an average center of mass momentum for the Reid, Hamada-Johnston and Bressel-Kerman-Rouben potentials.
Abstract: Nuclear matter calculations have been carried out for the Reid, Hamada–Johnston, and Bressel–Kerman–Rouben potentials. The convergence of the reference spectrum series for the G matrix is investigated, as is the approximation of choosing an average center of mass momentum. Higher-order cluster contributions are estimated from the scaling formulas of Day. The Reid potential predicts saturation at kF = 1.49 fm−1, with a binding energy −13.7 ± 1.5 MeV per particle.
TL;DR: In this article, the librational motion in the α phase of solid N2 and CO has been studied in the approximation that the centers of mass of the molecules are fixed at the lattice sites (i.e., no translational motion).
Abstract: The librational motion in the α phase of solid N2 and CO has been studied in the approximation that the centers of mass of the molecules are fixed at the lattice sites (i.e. no translational motion...
TL;DR: In this article, the authors obtained expressions for the decrement and modulus defect due to the breakaway of a dislocation from a row of equally spaced pinning points, using expressions for activation energy given in an earlier paper.
Abstract: : By algebraic methods, this paper obtains expressions for the decrement and modulus defect due to the breakaway of a dislocation from a row of equally spaced pinning points, using expressions for the activation energy given in an earlier paper. The model is that of Teutonico, Granato, and Lucke, but incorporating a pinning force of general shape.
TL;DR: In this article, the quenching and depolarization of mercury resonance radiation (2537 A ) induced by collisions of Hg(63P1) atoms with various molecules has been investigated using the method of delayed coincidences.
Abstract: The quenching and depolarization of mercury resonance radiation (2537 A), induced in collisions of Hg(63P1) atoms with various molecules has been investigated using the method of delayed coincidences. The following total quenching cross sections have been obtained for the process Hg(63P1) → Hg(63P0, 61S0): Hg–H2, 24.6 A2; Hg–D2, 22.7 A2; Hg–CO, 21.7 A2; Hg–CO2, 10.2 A2; Hg–O2, 60.5 A2; Hg–14N2, 0.73 A2; Hg–15N2, 0.78 A2; and Hg–Xe, < 0.002 A2. A cross section of 267 A2 has been measured for the depolarization of the resonance radiation by collisions with CO2 molecules.
TL;DR: The vibrational levels of the 3dσ,π Rydberg complexes of the NO molecule were studied in this article, and the spin-orbit effects of the crossing between the 3Dσπ,π(ν) and B2Π(ν = 23) rotational levels were analyzed.
Abstract: The vibrational levels of the 3dσ,π Rydberg complexes of the NO molecule are studied. They give rise to absorption bands 3d–X in the vacuum ultraviolet, most of which are severely overlapped by other bands, and, in addition, to Rydberg–Rydberg emission bands in the visible (3d–3s) and in the infrared (3d–3p). Both types of spectra have been photographed at high resolution, the absorption spectra for three different isotopes.Interactions with non-Rydberg levels and predissociations are observed. A detailed analysis, including spin–orbit effects, is given of the crossing between the 3dσ,π(ν = 1) and B2Π(ν = 23) rotational levels. Off-diagonal matrix elements are determined and precise vibrational and rotational constants are calculated. Largely responsible for the unusual structure of the bands is the matrix element which is shown to be independent of ν.
TL;DR: In this article, the magnetic rotation spectrum of acrolein at 4040, 4069, 4122, 4178, 4220, and 4322 A. The first five bands are assigned to the 3A″−1A′ (π*n) transition of trans a...
Abstract: Six bands have been observed in the magnetic rotation spectrum of acrolein at 4040, 4069, 4122, 4178, 4220, and 4322 A. The first five bands are assigned to the 3A″–1A′ (π*–n) transition of trans a...
TL;DR: In this article, the interplanar surface relaxations of seven face-centered and nine body-centered cubic metals are calculated for their three low index surfaces, and it is found that the relaxation is closely related to a non-dimensional parameter, where α and r0 are parameters of the Morse potential.
Abstract: The interplanar surface relaxations of seven face-centered and nine body-centered cubic metals are calculated for their three low index surfaces. In f.c.c. lattices the relaxation for the three surfaces is in the order (110) > (100) > (111) whereas in b.c.c. lattices the order is (111) > (100) > (110). In general the relaxation is greater for b.c.c. metals than for f.c.c. Comparing different metals of the same structure, it is found that the relaxation is closely related to a non-dimensional parameter , where α and r0 are parameters of the Morse potential.
TL;DR: The nuclear spin-lattice relaxation time of 3He gas in contact with metallic and glass surfaces has been measured in this paper, and the relaxation time in the presence of a glass surface is strongly depe...
Abstract: The nuclear spin–lattice relaxation time of 3He gas in contact with metallic and glass surfaces has been measured. The relaxation time of the gas in the presence of a glass surface is strongly depe...
TL;DR: In this paper, the anomalous scattering of Bogoliubov excitations at sharp N-S and S-N boundaries as well as quasi-particle tunneling in N−S-N and S−N-S geometries are discussed.
Abstract: We give a systematic discussion of the anomalous scattering of Bogoliubov excitations at sharp N–S and S–N boundaries as well as quasi-particle tunneling in N–S–N and S–N–S geometries. The relation...
TL;DR: In this paper, the interactions between the lattice and the electronic excitations which luminesce can be understood in terms of a Franck-Condon model, and the value of the electron -LO phono...
Abstract: In CdS the interactions between the lattice and the electronic excitations which luminesce can be understood in terms of a Franck–Condon model. Calculations for the value of the electron – LO phono...
TL;DR: In this paper, the authors measured the energy spectra of 1H and 4He projectiles backscattered from thin Au films of known thicknesses and derived an analytical expression for the spectra in the limit of no multiple scattering.
Abstract: Energy spectra have been measured of 1H and 4He projectiles backscattered from thin Au films of known thicknesses. An analytical expression for the spectra is derived in the limit of no multiple scattering. Protons of energies ~50 keV are shown to give resolutions of a few A for depth measurements up to about 500 A, thus providing a useful technique for studying surface regions. The technique is illustrated by measurements of a nickel film before and after oxidation. Stopping cross sections for 1H and 4He in Au are obtained for energies 20 < E < 100 keV.
Abstract: Published rotational constants of the electronic states of H2O and D2O have been corrected for the effects of rotation electronic interaction. The corrected constants have been used to obtain a 'de...
TL;DR: In this paper, anisotropic intermolecular potential has been used to explain the rotational transitions in the ground vibrational state of H2-Xe Van der Waals complexes.
Abstract: Spectra of H2–Ar, H2–Kr, and H2–Xe Van der Waals complexes, accompanying the Q1(0), Q1(1), S1(0), and S1(1) transitions of the pressure-induced fundamental infrared absorption band of hydrogen, have been studied in gas mixtures at 93–180 °K with a path length of 13 m and total pressures of ~3 atm. The main features of the spectra correspond to rotational transitions in the ground vibrational state of the complex, i.e., resolved T and N lines (Δl = ± 3) and unresolved R and P lines (Δl = ± 1), where l is the rotational quantum number of the complex. The spectra are analyzed with eigenvalues derived from the wave-mechanical solution of the isotropic Lennard–Jones 12–6 potential with constants determined from the combination rules for mixed molecular species. Although there is good overall agreement, it is evident that finer details of the spectra will require the introduction of an anisotropic intermolecular potential for their explanation.
TL;DR: In this article, the fundamental rotation-vibration band of H2 induced by an electric field has been measured at high resolution using an interferometer with a limit of resolution of 0.006 cm−1.
Abstract: The fundamental rotation–vibration band of H2 induced by an electric field has been measured at high resolution using an interferometer with a limit of resolution of 0.006 cm−1. The frequencies and the widths of the absorption features have been measured in the density range 1 to 25 amagat, and zero-density frequencies have been obtained by extrapolation. The lines exhibit collision narrowing, the minimum width, 0.01 cm−1, occurring at a density of about 2 amagat. A new value, 1.2 cm3, has been obtained for the matrix element of the polarizability.
TL;DR: In this article, the energy and shape of the excitation cross-section of Ar were found for the first time in the ionization curve of Ar between 24 and 29.5 eV.
Abstract: Clearly resolved structures are reported for the first time in the ionization curve of Ar between 24 and 29.5 eV. We have found the energy and the shape of the excitation cross section for several ...
TL;DR: In this article, the authors studied Josephson tunneling in lead, lead oxide, copper, and lead junctions with the intent of investigating the proximity effects between normal (Cu) and superconducting (Pb) metals.
Abstract: We have studied Josephson tunneling in lead – lead oxide – copper – lead junctions with the intent of investigating the proximity effects between normal (Cu) and superconducting (Pb) metals. Zero-v...
TL;DR: In this paper, a transversely excited atmospheric TEA-CO2 laser with a helical electrode configuration is described and analyzed, which possesses a radial gain profile which naturally favors a toroidal configuration.
Abstract: A transversely excited atmospheric TEA–CO2 laser having a helical electrode configuration is described and analyzed. This laser configuration possesses a radial gain profile which naturally favors ...
TL;DR: The first nine coefficients have been derived in the exact high temperature expansion of the fluctuation in the long range order in the XY model on the triangular and square lattices as discussed by the authors.
Abstract: The first nine coefficients have been derived in the exact high temperature expansion of the fluctuation in the long range order in the XY model on the triangular and square lattices. For the triangular lattice seven coefficients have also been obtained in the expansion of the fourth-order fluctuation. The method of conformal transformations has been developed in a form suitable for the analysis of series of this type. Clear evidence is obtained in favor of a phase transition for which the critical index of the fluctuations is γ ≈ 3/2. The critical temperatures kTC/J for the triangular and square lattices are 1.500 ± 0.006 and 0.900 ± 0.006 respectively.
TL;DR: In this paper, the channeling behavior of 1-MeV He+ ions and deuterons in U4O9 has been studied in order to provide information on the location of the excess oxygen in the fluorite structure of UO2.
Abstract: The channeling behavior of 1-MeV He+ ions and deuterons in U4O9 has been studied in order to provide information on the location of the excess oxygen in the fluorite structure of UO2. Wide-angle (Rutherford) scattering was used to study the channeling behavior with respect to the uranium sublattice, and the 16O(d, p)17O reaction was used to investigate the oxygen sublattice. A pronounced disorder in the oxygen sublattice was indicated by very poor channeling properties and strong dechanneling with increasing depth. The data are thus in conflict with the model incorporating the excess oxygen in the regular interstitial positions along the uranium rows; on the other hand, they are consistent with the more recent model of Willis in which the excess oxygen atoms are displaced ~ 1 A from the regular interstitial sites and displace, in addition, some normal oxygen atoms. Channeling with respect to the uranium sublattice was found to be substantially the same as in stoichiometric UO2—but with a somewhat smaller ...
TL;DR: The velocity of sound for both transverse and longitudinal waves has been measured in single crystals of pure gallium and these velocity data have been used to calculate a complete set of elastic cons as discussed by the authors.
Abstract: The velocity of sound for both transverse and longitudinal waves has been measured in single crystals of pure gallium These velocity data have been used to calculate a complete set of elastic cons