Canadian Journal of Physics
0008-4204
1208-6045
Canada
Cơ quản chủ quản: National Research Council of Canada , Canadian Science Publishing
Lĩnh vực:
Physics and Astronomy (miscellaneous)
Phân tích ảnh hưởng
Thông tin về tạp chí
Published since 1951, this monthly journal reports significant advances in research in physics, including atomic and molecular physics; condensed matter; elementary particles and fields; nuclear physics; gases, fluid dynamics, and plasmas; electromagnetism and optics; mathematical physics; interdisciplinary, classical, and applied physics; relativity and cosmology; physics education research; statistical mechanics and thermodynamics; quantum physics and quantum computing; gravitation and string theory; biophysics; aeronomy and space physics; and astrophysics. It publishes research articles, rapid communications, and review articles contributed by recognized experts in Canada and abroad. It also publishes special issues dedicated to current research in a particular area of physics.
Các bài báo tiêu biểu
THE ABSORPTION SPECTRUM OF CF<sub>2</sub> The absorption spectrum of CF2 in the 2 500 Å region has been photographed at high dispersion, and the rotational structure of a number of bands has been analyzed. The analysis of the well-resolved subbands establishes that these are perpendicular- rather than parallel-type bands, as previously assigned. Further analysis shows that the upper and lower electronic states are of 1 B1 and 1 A1 symmetries respectively, corresponding to a transition moment that is perpendicular to the plane of the molecule. In the upper electronic state, r0 (CF) = 1.32 Å and [Formula: see text], while in the ground state, r0 (CF) = 1.300 Å and [Formula: see text]. An investigation of the vibrational structure of the band system has shown that the vibrational numbering in ν2 ′ must be increased by one unit from earlier assignments, thus placing the 000–000 band near 2 687 Å (37 220 cm−1 ). A search between 1 300 and 8 500 Å showed two new band systems near 1 350 and 1 500 Å which have been assigned tentatively to the CF2 molecule.
Tập 45 Số 7 - Trang 2355-2374 - 1967
HORIZONTAL MOVEMENTS OF AURORA Measurements on the drifts of auroral forms at three stations to the south of the auroral zone in West-Central Canada failed to show evidence of a motion due to the earth's rotation relative to fixed excitation patterns in space. The distribution and the magnitude of the speed of auroral structures parallel and normal to the geomagnetic meridians are substantially the same as for non-luminous ionic irregularities observed by radio methods. The speed of an auroral arc or band parallel to the geomagnetic meridian is apparently constant. Speeds increase with geomagnetic activity, particularly in an east-west direction. There is no definite indication of a reversal of the east-west motions close to local midnight. Speeds and directions show no characteristic variations with the time of night.
Tập 36 Số 2 - Trang 160-170 - 1958
DISLOCATION DYNAMICS IN DEFORMATION AND RECOVERY Phenomenological equations between dislocation velocity, effective shear stress, temperature, and pressure are presented. It is suggested that the term "activation volume" be properly assigned to the pressure dependence of dislocation velocity. Indirect methods of determining velocity–stress relations are reviewed, and a new method is introduced using the stress–time data in stress relaxation. Some results are reported for high-purity iron, LiF, and NaCl crystals. Phenomenological relations near absolute zero are examined in the light of the third law of thermodynamics. These relations are illustrated with the deformation behavior of potassium at liquid helium temperatures.
Tập 45 Số 2 - Trang 493-509 - 1967
Optimum molecular constants and term values for the <i>X</i><sup>2</sup>Π(ν ≤ 5) and <i>A</i><sup>2</sup>Σ<sup>+</sup>(ν ≤ 3) states of OH Least-squares fits of 1618 A2 Σ+ –X2 Π frequencies, 774 X2 Π vibration–rotation frequencies, and 125 microwave frequencies have been made to effective 2 Σ+ and 2 Π Hamiltonians containing adjustable parameters for each vibrational level. The fitted parameters from each band, some of which included the microwave frequencies simultaneously, have been merged to obtain a set of 13 A ↔ X band origins and 91 single-valued parameters for A2 Σ+ , ν ≤ 3 and X2 Π, ν ≤ 5. The set of parameters reproduces the experimental frequencies with residuals which on the average are only about 1.12 times larger than the estimated precisions of the data. Tables of term values calculated from the merged constants are reported for the two states.
Tập 58 Số 7 - Trang 933-949 - 1980
THE TRANSPORT OF HEAT BETWEEN DISSIMILAR SOLIDS AT LOW TEMPERATURES The resistance offered to the flow of heat by the mismatch of the elastic constants at the interface between two materials has been calculated. It is shown that for a perfectly joined interface the heat flow is proportional to the difference of the fourth powers of the temperature on each side of the interface. Deviations from this temperature dependence are to be expected for rough surfaces and for surfaces pressed into contact with one another. The calculated contact resistance between some common solids is given, and graphs are presented from which the heat flow between any two materials may be computed. It is shown too that the spin–phonon, phonon–electron, and phonon–phonon relaxation processes give rise to additional resistive processes in some solids, some of which restrict the heat flow at the surface. The theoretical results compare well with the available experimental data. However, the problem of the contact resistance between helium and metals is still unresolved. A tentative explanation of this is presented which predicts that there should be an appreciable difference between the contact resistance of a metal in the normal and in the superconducting state.
Tập 37 Số 3 - Trang 334-349 - 1959
Coexistence curve of the binary fluid nitrobenzene–heptane The liquid–liquid coexistence curve of the binary fluid nitrobenzene–heptane has been measured by interferometric means. The mole fraction concentration difference, ΔX, between the two liquid phases is equal to (0.205 ± 0.010)[(Tc − T)/Tc ]β with β = 0.3328 ± 0.0020. The critical concentration is 0.470 ± 0.003 mole fraction nitrobenzene.
Tập 59 Số 7 - Trang 934-935 - 1981
Optical potential for light nuclei and momentum-space eikonal phase function The space radiation environment comprises all of the nuclei in the periodic table with energies that extend from a fraction of an MeV/n to TeV/n. The vast range of projectile–target and energy combinations necessitates highly efficient and accurate cross section codes for use in radiation transport codes. As particles in the space radiation environment impinge on shielding materials, nuclear reactions, such as nuclear fragmentation, occur. One way of estimating nuclear fragmentation cross sections is to use an abrasion–ablation model, which describes how nucleons are dislodged from the nuclei as a result of nuclear collisions and the mechanism by which excited pre-fragments decay via particle emission to more stable states. The well-known partial wave solution method cannot be used directly for the computation of abrasion cross sections. Instead, abrasion cross sections may be computed by slightly altering the Eikonal solution method, which is a high energy (small scattering angle) approximation that depends on the nucleus–nucleus optical potential. The aim of the current work is to present two efficient methods for the computation of the Eikonal phase shift function. Analytic formulas of the optical potential are presented in the position-space representation for nuclei that are well-represented by harmonic-well nuclear matter densities (A < 20), which reduces the Eikonal phase factor to an integration over a single dimension. Next, the Eikonal phase function is presented in the momentum-space representation, which is particularly useful when the Fourier transform of the position-space optical potential is known. These new methods increase the computational efficiency by three orders of magnitude and allow for rapid prediction of elastic differential, total, elastic, and reaction cross sections in the Eikonal approximation.
Tập 96 Số 6 - Trang 642-649 - 2018
THE STRESSES PRODUCED BY A SCREW DISLOCATION PILEUP AT A CIRCULAR INCLUSION OF FINITE RIGIDITY The method of continuously distributed dislocations is used to obtain the exact solution for the distribution of screw dislocations in a linear array of length L piled up against a circular inclusion of radius R and finite shear modulus. The solution presented is valid for 0 < G2 /G1 < ∞, where G2 is the shear modulus of the inclusion and G1 is the matrix shear modulus.The solution enables one to study simultaneously the effects of second-phase size and rigidity upon N, the number of dislocations in the pileup, and upon the local stresses induced in the second phase. In the second phase close to the pileup tip it is shown that the local stresses vary as: (1) (2L/ρ)g , when the inclusion diameter is much greater than the slip line length; [Formula: see text], when the particle diameter is much less than the slip line length, ρ is the radial distance from the pileup tip, and g is a function only of the shear moduli ratio, G2 /G1 , with 0 < g < 1. The effects of varying second-phase size and rigidity upon the magnitude of the local stresses is explained in terms of image dislocation forces generated by the presence of the inhomogeneity ahead of the pileup.
Tập 45 Số 2 - Trang 841-863 - 1967
Saturn upper atmospheric structure from Cassini EUV and FUV occultations <sup>1</sup>This article is part of a Special Issue that honours the work of Dr. Donald M. Hunten FRSC who passed away in December 2010 after a very illustrious career. Stellar occultations of the Saturn atmosphere using the Cassini ultraviolet imaging spectrograph (UVIS) experiment have provided vertical structure at a range of latitudes. The transmission spectra in the extreme–far ultraviolet (EUV–FUV) range allow extraction of vertical profiles of H2 and hydrocarbon abundances from the top of the atmosphere to about 300 km above the 1 bar (1 bar = 100 kPa) pressure level. A reanalysis of the Voyager 2 δSco occultation in 1981 is consistent with the original report. The hydrocarbon homopause is near a pressure of 0.2 μbar in the UVIS analysis, compared to ∼0.01 μbar obtained from the Voyager occultation. Measured hydrocarbon abundances are obtained in the pressure range 600–0.1 μbar in the Cassini UVIS experiment. The combined UVIS results provide evidence for significant latitudinal dependence of vertical temperature profile. The confinement of the hydrocarbons in the current observations compared to published models and the Voyager ultraviolet spectrograph (UVS) results at solar maximum, infer smaller eddy diffusion coefficients in this epoch. Model calculations indicate that the latitudinal dependence of H2 vertical displacements is caused primarily by the combined effects of gravitational potential and evident differences in electron energy deposition at the top of the atmosphere affecting the temperature profile. The derived H2 density profiles from ~–40° latitude and others close to the equator, are found to be nearly identical on a pressure scale below the exobase. The inference is that that the pressure profile of H2 density at Saturn is unchanged over a broad range of latitudes.
Tập 90 Số 8 - Trang 817-831 - 2012
ABSORPTION SPECTRA OF BENZENE AND BENZENE-<i>d</i><sub>6</sub> IN THE VACUUM ULTRAVIOLET The absorption spectra of benzene and benzene-d6 have been photographed from 1300 Å to 1850 Å in the first order of a 21-ft. normal incidence vacuum spectrograph. The band analysis resulted in the identification of four Rydberg series (over one hundred vibrational bands) in each molecule, converging to ionization potentials of 9.247 ev. (benzene) and 9.251 ev. (benzene-d6 ). Progressions of the ν2 , ν18 , and ν20 vibrations are associated with most of the 31 observed Rydberg transitions, and vibrational constants are tabulated for each. The strong intensity and the unusual length of the upper state ν18 (e2g ) progression in comparison with the ν2 (a1g ) progression are interpreted in terms of the Jahn–Teller theorem, and it is concluded that the stable equilibrium nuclear configuration in the Rydberg states is of D2h symmetry.
Tập 34 Số 6 - Trang 596-615 - 1956