• Volume 7, Issue 6

December 1976,   pages  369-433

• The true potential energy curves for different states of SiO and SiS molecules

The true potential energy curves forX1Σ+, a3πr,A1π,e3Σ,E1Σ+,c3πi states of astrophysically important molecule SiO, whose spectra were observed in the sunspots, have been constructed using the method of Lakshman and Rao. Dissociation energy and ionization potential have been estimated as 65,350 cm−1 and 92,854 cm−1 respectively and found to be in good agreement with the values cited in literature.

The true potential energy curves forX1Σ+,D1π andE1Σ+ states of SiS molecule have been constructed by the same method and its dissociation energy in the ground state has been estimated using Hulburt-Hirschfelder potential function as 54,765 cm−1 in good agreement with 53,250.9 cm−1 given by Herzberg.

• The effect of magnetic fields and boundary conditions on the shear flow of nematics

The flow of a nematic liquid crystal between plane parallel plates, with one plate moving with uniform velocity relative to the other, is discussed. The apparent viscosity, orientation and velocity profiles are computed forp-azoxyanisole as functions of shear rate and magnetic field for symmetric and asymmetric molecular alignment at the plates. For symmetric homeotropic boundary condition, a magnetic field applied along the flow direction exhibits a threshold reminiscent of a Freedericksz transition in the hydrostatic case. In general the apparent viscosity for the asymmetric boundary condition is less than that for the symmetric case.

• Excitation of multilayered plasma columns with the ring of magnetic currents

The excitation of gaseous plasma column having semiconductor plasma columns on either side is studied with the excitation source being the ring of magnetic currents. The whole structure being cylindricalin shape, contains the conductor along its axis. The effect of radii of all the columns including that of the ring on radiation pattern, is studied which shows a peak of maximum radiation in a certain direction along with some other less ntense peaks. In most cases the peak occurs roughly at 61° at which fine structure is given. Also three intense peaks of radiation occur when radius of the plasma (outer semiconductor) column is 0.058 m.

• Diffracted field characteristics of Straubel class of apodisation filters

The diffracted field characteristics of Straubel class of apodisation filters have been investigated with reference to point spread function, relative central intensity, total transmission factor, Strehl ratio, second order moment, encircled energy and dispersion factors.

• Thin film thickness step gauge

The Blodgett-Langmuir technique is used to deposit multilayer films of barium stearate on EDF glass. The thickness of the film varies in steps of 10 monolayers, and the thickness of each monolayer is about 25 Å. When viewed in white light at near normal incidence vivid interference colours are seen in reflection, with good contrast between adjacent steps. The reliability of the step gauge is tested for dielectric films of MgF2.

• Infrared spectra of BeSO4.4H2O and its deuterated analogue at 110K in 1200–250 cm−1 region

IR absorption spectra of BeSO4.4H2O and its deuterated analogue are reported in the region 1200–250 cm−1 at 110 K. The half-widths and relative integrated intensities of the bands are also reported. The study largely confirms the assignments for thev3 andv4 modes of SO42− ion and thev3 mode of Be(aq)42+, complex as made by Diemet al. The assignments of the other modes of SO42− and Be(aq)42+, and the librational modes of water are given a more solid footing as result of the present investigation.

• Nuclear level densities in self-consistent field approximation

The effect of two-body nature of the nuclear shell model potential on the recent numerical calculations of the nucleai level density has been examined. For the two most widely used single particle energy level schemes based on harmonic oscillator and Woods-Saxon potential, this effect is shown to significantly modify the excitation energy dependence of the level densisties.

• A bound on the number of bound states in the Schrödinger equation

A boundSl is given for the number of bound statesni in thelth partial wave corresponding to a spherically symmetric potential in non-relativistic quantum mechanics. This bound is given by$$n_\iota = \mathop \smallint \limits_0^\infty |V_a (l,r)|^{1/2} dr/\pi + 1$$ whereVa(l, r) is the attractive part of the effective potentialV(r)+l(l+1)/r2. Extensive comparative study ofSi and the Bargmann inequality is made.

• Effect of electrolytic colouration on dislocation density in KBr and KCl

Average dislocation density in a number of electrolytically coloured and uncoloured crystals of KBr and KCl has been measured using the etch-pit technique. A decrease in density of dislocation after electrolytic colouration has been observed. This is attributed to the change in the dislocation pattern inside the crystals during colouration to produce more number of vacancies under the typical conditions of large electric field gradient at high temperature.

• On the behaviour of Er3+ ion in tetragonal crystalline field

Crystal field parameters for ErGaG and Er3+ YAlG and used to compute the temperature dependence of Schottky specific heat, paramagnetic susceptibility, magnetic anisotropy,μeff and quadrupole splitting in the range 10–400 K. The hyperfine interaction parametersA andB for166Er and167Er in both the systems are also obtained and in turn used to estimate the nuclear specific heat contribution. The studied parameters compare well with the available experimental results.

• # Pramana – Journal of Physics

Current Issue
Volume 93 | Issue 6
December 2019

• # Editorial Note on Continuous Article Publication

Posted on July 25, 2019