Volume 46, Issue 4
April 1996, pages 245-314
pp 245-257 April 1996 Review
There exist inhomogeneous electromagnetic and elastic waves with linear, quadratic and cubic coordinate dependence of amplitude, in addition to the usual plane harmonic waves in crystals. This article is concerned with conditions for initiation of such waves and mathematical techniques for their description. New types of electromagnetic waves with quadratic and cubic coordinate dependence of amplitude on the transverse coordinate in a transparent biaxially anisotropic plate are found. Any transparent biaxial crystal is demonstrated to have an infinite set of cuts, each suitable for initiation of one or more such waves.
pp 259-270 April 1996 Research Articles
Values of dielectric constant (ε′) and loss factor (ε″) have been experimentally determined for binary liquid mixtures of ethyl methyl ketone+ethylenediamine and methyl isobutyl ketone+ethylenediamine at 9.44 GHz microwave frequencies at 30°C. The values ofε′ andε″ have been used to evaluate the molar polarization, apparent polarization and the excess permittivities. Excess refractive index, viscosity and activation energy of viscous flow have also been estimated. These parameters have been used to explain the formation of 1:1 complexes for both the systems.
pp 271-275 April 1996 Research Articles
A simple one dimensional diatomic chain model is proposed to explain the reflectivity spectra of TmTe as observed by Wardet al. It is suggested that the system undergoes a structural phase transition of order-disorder type at 4.2 K, where the new phase assumes an anti-ferroelectric type of arrangement of the atoms. The results, we obtained, agree well qualitatively with the experimental results.
pp 277-281 April 1996 Research Articles
In the fluorinated La2CuO4−x prepared using a solid state reaction with NH4HF2 as a fluorinating agent at 550 K at ambient pressure, superconductivity was detected by microwave and EPR techniques with aTc of 35 K.
pp 283-288 April 1996 Research Articles
The generation of harmonics in a laser ablated YBCO film deposited on a 〈100〉 MgO substrate is reported. Higher odd harmonics appeared when the film was subjected to an ac field. The presence of a dc field induces only the second harmonic with a small value of slope ofV2−Hdc curve (δV2/δHdc) compared to bulk YBCO. The variation of the amplitude of third harmonic (V3) withHac and temperature was studied. These results are explained in terms of a critical state model. The observation of only a small amplitude of second harmonic (V2) with a smallδV2/δHdc is explained in terms of a special kind of clean grain boundary present in YBCO laser ablated films on 〈100〉 MgO.
pp 289-298 April 1996 Research Articles
We report the results of Compton profile study on polycrystalline tantalum. Measurements have been made using 59.54 keV gamma-rays. The results are compared with the APW band structure calculations of Papanicolaouet al and other available data. In contrast to the work of Changet al the overall agreement is better with the APW band structure which worsens on incorporating the electron correlation correction. Estimates of the errors due to the contribution from bremsstrahlung, non-validity of impulse-approximation and anomalous dispersion are also briefly discussed.
pp 299-304 April 1996 Research Articles
A distributed feedback dye laser based on second order Bragg scattering due to a sinusoidal susceptibility modulation is reported. Rhodamine 6G dye solution in three different solvents; methanol, ethanol and benzyl alcohol is pumped by interference fringes produced by two beams from the second harmonic of Nd:YAG laser. Output power is plotted as a function of the pump power. The spectrum of dye laser shows a new type of modulation.
pp 305-314 April 1996 Research Articles
A nonlinear quintic Schrödinger equation (NLQSE) is developed and studied in detail. It is found that the NLQSE has soliton solutions, the stability of which is analysed using variational method. It is also found that the soliton pulse width in the materials supporting NLQSE is small compared to soliton pulse width of the commonly studied nonlinear cubic Schrödinger equation (NLCSE).
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