Showing papers in "Physics Letters A in 1968"

TL;DR: In this paper, the critical distance and probability of energy transfer between a number of luminescent centres in oxidic phosphors have been arrived at by two independent methods, based on two independent algorithms.

TL;DR: The theoretical analysis of the influence of the fluctuation pairing on the conductivity of a normal film leads to the law σ = σ res + e 2 (T−T c ) 16 d h T c in good agreement with experimental data as discussed by the authors.

TL;DR: In this paper, a simple macroscopic derivation of the non-retarded Van der Waals interaction between two semi-infinite dielectric media is given, based on a simple linear combination of the Van der Wals interaction.

TL;DR: In this article, the branch of longitudinal electric modes was used for Bose condensation and the excitation energy was channelled into the mode with lowest frequency in a manner typical for BOSE condensation.

TL;DR: In this paper, a unified semi-empirical formulae for the mean charge and width of fast ion beams after their passing through solids have been obtained for all particles with atomic number Z ⪆ 20.

TL;DR: The ultrashort pulses generated by a Nd:glass laser have frequency swept carriers and can therefore be compressed by a pair of gratings to a length much closer to the reciprocal of the bandwidth as discussed by the authors.

TL;DR: In this paper, the angular distribution of desorbeded H2 molecules has been studied and the measured angular distributions are strongly peaked forward, indicating that they are not uniformly distributed.

TL;DR: In this article, boundary scattering, which affects the low frequency phonons, can be important in relatively large crystals in a solid solution, even at high temperatures, and boundary scattering is strongly scattered by point imperfections.

TL;DR: In this article, it was shown that characteristic X radiation following the ionization of an inner electron (n, l > 0, j > 1 2 ) by electron or proton impact should generally be polarized.

TL;DR: An emission line of CuC1 is observed at low temperature when the crystal is excited by high intensity u.v. laser light as discussed by the authors, but it is not observed with low intensity.

TL;DR: A new family of solutions of the Einstein-Maxwell equations with λ term was presented in this article, combining many well known but previously unrelated metrics, including the vacuum solutions of De Sitter, Kasner, Taub-N.U.T. and Kerr, within a single formula.

TL;DR: In this article, mode-locking in a rhodamine 6G-laser with 3.3′-diethyloxadicarbocyanineiodide as saturable absorber is reported.

TL;DR: In this article, the stability of the steady state was exploited to calculate the distribution function for free carriers in an electric field without introducing approximations in the form of the distribution functions.

TL;DR: In this article, a very similar fluorescence structure is obtained from the radiation of an ideally mode-locked laser and of a free-running laser with the same oscillating bandwith.

TL;DR: The water bag model for a collisionless electron plasma is strictly equivalent to the hydrodynamic model as discussed by the authors, and the introduction of a stream function and the linearisation of the pressure term give a solution valid for small nonlinearity and long wavelength.

TL;DR: In this article, the dependence of the superconducting transition temperature on the concentration of Gd spins is reported for La 1− x Gd x Al 2, and the results are in good agreement with the theory of Abrikosov and Gor'kov to concentrations very near the critical concentration.

TL;DR: In this paper, chemical effects on the isomer shift in 151 Eu were investigated systematically and calibrated to derive the change of the mean square charge radius due to the 21.7 keV transition.

TL;DR: In this article, the resistivity of single crystals of RuO 2 and IrO 2 in the temperature range 4.2°K -1000°K was investigated and a relation based only on interband scattering was found to fit rather well to the measured temperature dependence of resistivity.

TL;DR: In this paper, it was shown that large numbers of point contact junctions can be coupled together to form a coherent source of far infra-red radiation, which is known as point contact junction coupling.

TL;DR: In this paper, the high-temperature expansion of all the quantum-mechanical virial coefficients of a gas of ν-dimensional hard spheres is determined in first order in λ d.

TL;DR: In this article, various ferromagnetic quantities, Curie temperature, spin susceptibility, etc., for fcc Ni-alloys are calculated in the band model and the Invar effect for Fe-Ni alloys is discussed.

TL;DR: In this article, the effect of fluctuations on conductivity above and near the normal superconducting transition was calculated by means of the time dependent Ginzburg-Landau equation.

TL;DR: In this article, an instability of the off resonance modes in a continuously pumped, homogeneously broadened, two level ring laser was shown to exist if the pumping is strong enough and the cavity length is chosen properly.

TL;DR: In this article, high resolution of magnetic structures in superconductors is obtained by means of the Faraday effect applying thin evaporated EuSEuF 2 films of high specific Faraday rotation.

TL;DR: In this paper, the asymptotic behavior of ultrasonic attenuation near the critical points of isotropic Heisenberg magnets is studied with the help of the scaling law ideas.

TL;DR: In this paper, an analytical solution of the linearized Boltzmann equation of Abrikosov and Khalatnikov has allowed the transport coefficients of a Fermi liquid for thermal conductivity, viscosity and spin diffusion to be expressed as a rapidly converging series.

TL;DR: In this paper, a narrow spectral output (100 A) was obtained from 1, 11-diethyl-γ-cyano- 2, 21-dicarbocyanine tetrafluoro-borate by employing an echelle grating and a Fabry-Perot etalon in a novel, longitudinally pumped, dye laser system.

TL;DR: In this paper, the paramagnetic resonance spectra of Nd3+, Dy3+, Er3+ and Yb3+ in YVO4 were measured at X and Ka bands and at 4.2 and 1.8°K.

TL;DR: In this article, a 1.1′-diethyl-gl-nitro-4.4''-dicarbocyanine-tetrafluoro-borate dye laser with a 150 MW mode-locked ruby laser of the same transit time was used.

TL;DR: The observed changes of positron lifetimes in Na and Ga on melting are at variance with the predictions of the free electron gas model as mentioned in this paper, and they appear to be determined by the increase in vacancy concentration on melting.