The critical curve of a transition of the second kind in an antiferromagnetic superconductor (AFS) with nonmagnetic impurities has been studied. The AFS is described by using the mean-field model given by Nass, Levin,...
详细信息
The critical curve of a transition of the second kind in an antiferromagnetic superconductor (AFS) with nonmagnetic impurities has been studied. The AFS is described by using the mean-field model given by Nass, Levin, and Grest and assuming a one-dimensional electron band. We find that the points on the critical curve satisfy the thermodynamic stability condition for 0≤α1τ/Δ0≤5.04 and 0.49≤HQτ/Δ0≤***α1is the inverse lifetime of a conduction electron for nonmagnetic impurity scattering,HQis the antiferromagnetic molecular field, Δ0is the zero-temperature order parameter of a superconductor in the absence ofHQand impurities. Further, α1τand HQτdenote the values of these quantities for points on the critical curve. For α1τ/Δ0>5.04 and HQτ/Δ0>1.64, the phase transition from the superconducting to the normal state is always of the second kind. Some thermal properties of the system near the critical curve have also been investigated and we find that these depends dramatically on the
The spin-lattice relaxation time of the 31P nucleus in the phosphate group of egg yolk phosphatidylcholine multilamellar dispersions has been investigated at four resonant frequencies (38.9, 81.0, 108.9, and 145.7 MHz...
The spin-lattice relaxation time of the 31P nucleus in the phosphate group of egg yolk phosphatidylcholine multilamellar dispersions has been investigated at four resonant frequencies (38.9, 81.0, 108.9, and 145.7 MHz) in the temperature range from -***. to ***. C. The observed frequency dependence of the relaxation indicates that both dipolar relaxation and relaxation due to anisotropic chemical shielding are significant mechanisms. The experimental data have thus been modeled assuming both mechanisms and the analysis has allowed the contribution of each to the relaxation to be determined along with the correlation time for the molecular reorientation as a function of temperature. Dipolar relaxation was found to dominate at low nuclear magnetic resonance frequencies while at high frequencies the anisotropic chemical shift dominates. The correlation time of the phosphate group is on the order of 10-9 s at ***. C and increases to .apprx. 10-7 s at -***. C. It is observed that the freezing of the buffer which occurs at .apprx. -***. C has a significant effect on the phosphate group reorientation. This effect of the freezing is to change the activation energy for the phosphate group reorientation from 16.9 KJ/mol above -***. C to 32.5 KJ/mol below -***. C.
A quantitative relationship has been identified between the deposition parameters and the electrical and optical properties of a-Si:C thin films. The major effects of the deposition parameters derive from their influe...
详细信息
A quantitative relationship has been identified between the deposition parameters and the electrical and optical properties of a-Si:C thin films. The major effects of the deposition parameters derive from their influence on the incorporation of water vapour into the films. Even very small changes in the amount of water vapour, as an ambient during deposition, produce very large changes in the electrical and optical properties of the films. An increase in the ambient water vapour pressure from 1 × 10 −8 to 4 × 10 −8 Torr decreases the room temperature conductivity of the resulting films by as much as three orders of magnitude. The important deposition parameters are expressed in terms of a quantity N H 2 O , which represents the actual amount of water which remains in the film.
We describe the results of the numerical integration of the equations of motion of a 17-particle chain with fixed ends and linear and cubic nearest-neighbour forces. Detailed graphs of mode energies, mode trajectories...
We describe the results of the numerical integration of the equations of motion of a 17-particle chain with fixed ends and linear and cubic nearest-neighbour forces. Detailed graphs of mode energies, mode trajectories, variation of the orbit periods and the squared modulus of the discrete Fourier transforms of mode displacements are shown for the case of the chain excited from rest in the 11th mode. The total system energy is always conserved to better than 0.02%. An additional 100 histories of this chain were calculated and stored for the same starting energy and a variety of starting velocities and displacements of the 11th mode. The data gathered constituted a constant energy ensemble. A coarse grained energy distribution function and corresponding Boltzmann H -functions were calculated for each mode. These H -functions proved to drop reversibly with time to a minimum value, indicating that each mode has reached a statistical equilibrium state. The mode energy distribution functions in this equilibrium state are shown to take a Maxwell-Boltzmann form. The associated mode temperatures range in value over two orders of magnitude.
The lattice vibrations and internal modes of polycrystalline CH 2 I 2 and CD 2 I 2 have been studied as a function of temperature using Raman and far-infrared spectroscopy. CH 2 I 2 has two stable phases, one of which...
The lattice vibrations and internal modes of polycrystalline CH 2 I 2 and CD 2 I 2 have been studied as a function of temperature using Raman and far-infrared spectroscopy. CH 2 I 2 has two stable phases, one of which is metastable in the temperature range of the other, and a second metastable phase. CD 2 I 2 has only one solid phase. Possible structures for the various phases are discussed.
Spectra have been recorded from monochromatized Kα 1 , Kβ 1 and Lα 1 X-rays in the 3—16 keV energy region incident on an Si(Li) detector. An analytic lineshape consisting of a Gaussian plus two Gaussian-exponentia...
Spectra have been recorded from monochromatized Kα 1 , Kβ 1 and Lα 1 X-rays in the 3—16 keV energy region incident on an Si(Li) detector. An analytic lineshape consisting of a Gaussian plus two Gaussian-exponential convolutes fits these well, except at very low energy. The intensities and parameters of these tails are explored in the context of the processes responsible, and the behaviour of the shorter tail is compared with the predictions of a model calculation of Auger and photoelectron escape. The well behaved energy dependence of the tailing parameters improves the prospects for more accurate fitting of complex XRF, EPMA and PIXE spectra.
The various mechanisms giving rise to low-energy peak tailing in Si(Li) X-ray detectors are discussed. The Hypermet lineshape function is shown to be satisfactory in the energy range 4–15 keV. Stringent tests of the ...
The various mechanisms giving rise to low-energy peak tailing in Si(Li) X-ray detectors are discussed. The Hypermet lineshape function is shown to be satisfactory in the energy range 4–15 keV. Stringent tests of the X-ray relative intensity database used in PIXE, performed with detectors of accurately known lineshape, lend it strong support. Current measurements of the L subshell fluorescence and Coster-Kronig yields indicate that the latter may be systematically lower than theory.
The rotational structure of the D 2 Σ + →A 2 Σ + transition of 4 HeD is highly perturbed, and this is caused by the near degeneracy of the D, ν=0 and C, ν=3 vibrational levels. A perturbation analysis is presente...
The rotational structure of the D 2 Σ + →A 2 Σ + transition of 4 HeD is highly perturbed, and this is caused by the near degeneracy of the D, ν=0 and C, ν=3 vibrational levels. A perturbation analysis is presented which yields the spectroscopic constants for both of the perturbing levels, yielding the first experimental information on a vibrationally excited state of HeH.
作者：
ALEXANDER, MEDepartment of Physics
Guelph-Waterloo Program for Graduate Work in Physics University of Guelph Guelph Ontario N1G 2W1 Canada
The gravitational potential energy of tidal interactions in a binary system is formulated as a perturbation Hamiltonian which couples the normal mode oscillations of the stars with their orbital motion in a self-consi...
The gravitational potential energy of tidal interactions in a binary system is formulated as a perturbation Hamiltonian which couples the normal mode oscillations of the stars with their orbital motion in a self-consistent way. The stellar oscillations are treated in the linear approximation for a non-rotating star. In order to examine resonances between normal mode oscillations and orbital motion, the Hamiltonian is transformed to action-angle variables of the zero-order problem. Approximate expressions are derived for the case of small orbital eccentricities and a pair of dominant stellar eigenmodes, characterized by a single value of the azimuthal indexm. The positions of exact resonance and motion in the vicinity of resonance is *** integration is performed on the tidal capture of two stars, using the self-consistent treatment. Angular momentum transferred to the stars as a result of tidal interactions is sufficiently large to invalidate the assumption (Press & Teukolsky) that the stars’ rotation can be ignored.
In a previous paper, we presented general eigenvalue equations for both transverse-electric (TE) and transverse-magnetic (TM) modes in multilayer slab waveguides. Here, those formulas are applied to symmetric periodic...
详细信息
In a previous paper, we presented general eigenvalue equations for both transverse-electric (TE) and transverse-magnetic (TM) modes in multilayer slab waveguides. Here, those formulas are applied to symmetric periodic stratified media. The results obtained are compared with those of Yeh et al, which were obtained by using matrix method. The eigenvalue equations for even and odd-modes are also obtained.
暂无评论