With the help of a suitable example we demonstrate the importance of the choice of the dynamical algebra in finding the invariants of time-dependent hamiltonians. Several cases of time-dependent oscillators are discus...
With the help of a suitable example we demonstrate the importance of the choice of the dynamical algebra in finding the invariants of time-dependent hamiltonians. Several cases of time-dependent oscillators are discussed briefly illustrating the algebraic method of finding the invariants.
It is shown that the plasma parameter obtained by fitting the presently available one-component-plasma structure factors to the real structure factors of the alkali liquids cannot be reasonably reproduced by existing ...
It is shown that the plasma parameter obtained by fitting the presently available one-component-plasma structure factors to the real structure factors of the alkali liquids cannot be reasonably reproduced by existing variational thermodynamic calculations, even using a very accurate pseudopotential theory. The implications of this discrepancy are discussed.
Raman and far-infrared spectra of crystalline fluoroform at temperatures between 20 and 106 K have been recorded. There is no evidence for any solid-state phase transitions, nor for hydrogen bonding. The rich lattice ...
Raman and far-infrared spectra of crystalline fluoroform at temperatures between 20 and 106 K have been recorded. There is no evidence for any solid-state phase transitions, nor for hydrogen bonding. The rich lattice spectra and crystal field splittings suggest that the unit cell is rather large, and possible structures are discussed.
The Scanning Laser Microscope at the University of waterloo is described, with experimental results from the areas of semiconductor characterization and device testing. Minority carrier diffusion length measurements u...
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The Scanning Laser Microscope at the University of waterloo is described, with experimental results from the areas of semiconductor characterization and device testing. Minority carrier diffusion length measurements using two different experimental geometries are described and compared with scanning electron microscope EBIC measurements. Both minority carrier diffusion length and surface recombination velocity measurements in polycrystalline semiconductors are reported from measurement of spatially-resolved photoconductivity along the length of a polycrystalline sample.
An apparatus is described for measuring Seebeck coefficients in semiconducting thin‐film samples with resistances as high as 101 1 Ω. A temperature gradient ΔT is produced across the sample by means of differential...
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An apparatus is described for measuring Seebeck coefficients in semiconducting thin‐film samples with resistances as high as 1011 Ω. A temperature gradient ΔT is produced across the sample by means of differential optical heating of the ends of the sample. The Seebeck voltage ΔV is measured using a specially designed amplifier circuit with an input impedance of 1013 Ω. The Seebeck coefficient is obtained from the slope of the plot of ΔV vs ΔT.
The effect of paramagnetic impurities in anisotropic superconductors is investigated with use of the Shiba-Rusinov theory for the impurities and the Eliashberg formalism for the host superconductor. The analytical exp...
The effect of paramagnetic impurities in anisotropic superconductors is investigated with use of the Shiba-Rusinov theory for the impurities and the Eliashberg formalism for the host superconductor. The analytical expressions for the transition temperature Tc and the specific-heat jump ΔC are derived with the use of the square-well model for the electron-phonon interaction. Considered as a function of the spin-flip scattering rate α, the quantities TcTc0 and ΔCΔC0 depend on the microscopic parameters λ, ωD, and μ* of the host material. The dependence on the material parameters becomes insignificant if the above properties are plotted versus ααcr or if ΔCΔC0 versus TcTc0 is studied. (Tc0 and ΔC0 are values of Tc and ΔC, respectively, in the absence of impurities, αcr is the value of α for which Tc becomes zero, λ is electron-phonon—interaction parameter, ωD is the Debye frequency, and μ* is the Coulomb pseudopotential.)
We derive a formula for calculating the free-energy difference between the superconducting and the normal states of a strong-coupling superconductor with localized states within the gap (induced by magnetic impurities...
We derive a formula for calculating the free-energy difference between the superconducting and the normal states of a strong-coupling superconductor with localized states within the gap (induced by magnetic impurities). The present formula is a generalization of the one given by Bardeen and Stephen (for the electron-phonon systems) to include the effect of Shiba-Rusinov impurities.
Shiba-Rusinov theory of magnetic impurities in isotropic superconductors beyond the s-wave scattering is generalized by using the Eliashberg formalism. The analytical expressions for the transition temperature Tc and ...
Shiba-Rusinov theory of magnetic impurities in isotropic superconductors beyond the s-wave scattering is generalized by using the Eliashberg formalism. The analytical expressions for the transition temperature Tc and the specific-heat jump ΔC are given using the square-well model for the electron-phonon interaction. Taken as a function of the impurity concentration, the quantities TcTc0 and ΔCΔC0 depend on the microscopic parameters λ, μ*, and ωD of the host material. However, this dependence is absent if one plots the above properties versus the normalized impurity concentration ααcr or if ΔCΔC0 vs TcTc0 is studied. (Tc0 and ΔC0 are values of Tc and ΔC, respectively, in the absence of impurities; λ is the electron-phonon interaction parameter, μ* the Coulomb pseudopotential, and ωD the Debye cutoff frequency; α is the spin-flip scattering rate; αcr is the value of α for which T becomes zero.)
It is pointed out that, due to the neglect of the natural line width of internal-conversion lines used for determining the instrumental resolution, the experiment of Lubimov et al does not determine a model-independen...
It is pointed out that, due to the neglect of the natural line width of internal-conversion lines used for determining the instrumental resolution, the experiment of Lubimov et al does not determine a model-independent lower bound for the neutrino mass.
The relative transition probabilities Kβ3Kβ1, Kβ2Kβ1, KO23Kβ1, KP23Kβ1, Kβ5Kβ1, and Kβ4Kβ1 are measured by Ge spectroscopy for the atoms having Z=70, 78, 82, and 92. In contrast to previous data, the results...
The relative transition probabilities Kβ3Kβ1, Kβ2Kβ1, KO23Kβ1, KP23Kβ1, Kβ5Kβ1, and Kβ4Kβ1 are measured by Ge spectroscopy for the atoms having Z=70, 78, 82, and 92. In contrast to previous data, the results exhibit smooth Z dependences and agree closely with Scofield's relativistic Hartree-Fock calculations. A tentative observation of the KM1 transition is reported.
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