Volume 31, Issue 4
October 1988, pages 1-322
pp 1- October 1988 Rapid Communications
We have measured the transport critical current densityJcof sintered YBa2Cu3O7, in various applied fields up to 185 Oe at 77 K. We find a sharp decay ofJcwith magnetic field. We show that this sharp decay is consistent with the low field hysteresis results of Groveret al. We argue that the observed field dependence is not caused by intragranular weak links.
pp 241-251 October 1988 Nuclear Physics
Self-energy correction to the shell model single-particle motion, arising from the excitation of octupole vibration in the intermediate state, accounts quite well for the energy shifts of the 2p1/2 and 1g9/2 proton orbits in zirconium nuclei.
pp 253-262 October 1988 Experimental Techniques
We describe a calorimeter which has been used to measure the heat capacity of small samples weighing 50 to 200 mg in the temperature range of 1.5 K to 20 K. We have used the thermal relaxation method as well the heat pulse method for our measurements with the same experimental set-up. An accuracy of better than 5% is obtained with this system.
pp 263-271 October 1988 Atomic Physics
The elastic differential cross-section forē-Na scattering in the presence of non-resonant laser field is studied for the exchange ofℓ=0, 1, 2 photons. The undressed contribution is evaluated within the framework of the eikonal Born series approximation and the effect of exchange is taken into account via the Ochkur approximation. The sodium atom has been treated in the frozen core approximation with special attention to the effect of the dressing of the target by the laser field. The ‘dressing’ of the target leads to quite an increase in the cross-section over the ‘undressed’ value near the forward direction for the exchange of one or two photons.
pp 273-280 October 1988 Atomic Physics
Triple differential cross-sections for the electron and positron impact ionization of atomic hydrogen and helium are calculated in a first order model using a product of two Coulomb wavefunctions for the final state continuum electrons supplemented by post-collision interaction effects.
pp 281-287 October 1988 Optics
Properties of a few saturable absorbers as candidates for low power optical phase conjugation (OPC) are examined. The specific systems studied are the dyes eosin, erythrosin B and Rose Bengal, doped in gelatin, polyvinyl alcohol and boric acid glass films. A method for quickly checking saturated absorption is suggested and demonstrated. Examples for OPC with these systems are cited and limitations are briefly discussed.
pp 289-307 October 1988 Liquids
Derivation of the thermodynamic properties of fluids of hard non-spherical molecules of arbitrary symmetry is based on the decoupling approximation. Theoretical expressions are given and calculations made for the equation of state and virial coefficients for hard ellipsoids. These results are compared with Monte Carlo values and show fair agreement in all cases. The theoretical predictions for the equation of state for binary mixtures are compared with the Monte Carlo results for hard spheres and hard prolate spherocylinders. Theoretical expressions for the first order quantum correction to the free energy, pressure and virial coefficients are also given. The quantum effects increase with increase of density and with increase of anisotropy parameter.
pp 309-312 October 1988 Solid State Physics
Ion-implanted phosphors were prepared by implanting Sb in CaS at 25 keV with concentration ranging from 0.05 to 0.2% by weight. Samples of similar concentration were also prepared using the conventional technique. The spectral response under UV excitation of both types of samples is compared.
pp 313-322 October 1988 Solid State Physics
The transmission spectra of Rhodamine B and Rhodamine 6G dyes coated on silver island films for various thickness were recorded. A strong coupling between the silver particle plasma resonance and the dye molecules is observed. The absorption of dye molecules increases when the absorption band of individual dyes and silver particles overlaps. In higher silver film thicknesses, transmission increases. The theoretical calculation using Maxwell-Garnett theory and Wang and Kerker’s results qualitatively supports the observed phenomenon. A red shift in the absorption peak of dyes on silver surfaces in comparison to solution phase absorption peak indicates photobleaching.
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