http://nopr.niscair.res.in/handle/123456789/2620 Search the Channel search http://nopr.niscair.res.in/simple-search http://nopr.niscair.res.in/handle/123456789/2696 Title: Nonlinear optical parameters of Raman scattered mode in weakly polar magnetized semiconductor-plasma <br/> <br/>Authors: Singh, M; Aghamkar, P; Duhan, S <br/> <br/>Abstract: This paper presents an analytical investigation of nonlinear absorption coefficient and refractive index of the Raman scattered stokes mode resulting from the nonlinear interaction of an intense pumping light beam with molecular vibrations of semiconductor-plasma. The origin of this nonlinear interaction lies in the third-order (Raman) susceptibility arising from the induced current density and density fluctuations generated within the medium. The total refractive index and absorption coefficient are determined through the effective susceptibility derived with the help of coupled-mode theory of plasmas. The effect of Szigeti effective charge (q) and magnetic field (β₀) has been introduced through equation of motion of lattice vibration and Lorentz force, respectively. The numerical estimates are made for n-type InSb crystal duly irradiated by a 10-nanosec pulsed 10.6 μm CO₂ laser. The Szigeti effective charge contributes the Raman susceptibility at moderate excitation intensity. At high excitation intensity, the contribution of Szigeti effective charge is wiped off and nonlinearity in the medium is only due to differential polarizability. In the absence of Szigeti effective charge, the magnitude of Raman susceptibility is found to agree with other theoretical quoted values. The analysis establishes that a small absorption coefficient and large refractive index can easily be obtained by proper selection of magnetic field and doping concentration under moderate excitation intensity in weakly polar semiconducting crystals which proves its potential as candidate material for the fabrication of cubic nonlinear devices. <br/> <br/>Page(s): 893-899 Mon, 29 Oct 2007 22:58:59 GMT http://nopr.niscair.res.in/handle/123456789/2695 Title: Dielectric dispersion in PbO-PbF₂-B₂O₃ glass system doped with Cr₂O₃ <br/> <br/>Authors: Rao, A Veerabhadra; Reddy, M Srinivasa; Kumar, V Ravi; Veeraiah, N <br/> <br/>Abstract: PbO-PbF₂-B₂O₃ glasses containing different concentrations of chromium ions (introduced as Cr₂O₃) ranging from 0 to 0.4 mol % were prepared. The dielectric properties i.e., constant Ɛ', loss tan δ, ac conductivity σac over a range of frequency and temperature of Pb glasses have been carried out. The results have been analyzed in the light of different oxidation states of chromium ions with aid of the data on differential scanning calorimetry, infrared, optical absorption and ESR spectra. The analysis indicates that when the concentration of chromium ions is up to ~ 0.3 mol %, these ions mostly exist in Cr₃₊ state, occupy network-modifying positions with CrO₆ structural units and at about 0.4 mol % a part of chromium ions seems to exist in Cr⁶⁺ state, adopting network forming positions with CrO₄²⁻structural units and causing an increase in the insulating strength of the glass. <br/> <br/>Page(s): 926-934 Mon, 29 Oct 2007 22:58:59 GMT http://nopr.niscair.res.in/handle/123456789/2694 Title: Vibrational spectra and normal coordinate analysis of adrenaline and dopamine <br/> <br/>Authors: Gunasekaran, S; Kumar, R Thilak; Ponnusamy, S <br/> <br/>Abstract: The FTIR and FTRaman spectra for adrenaline and dopamine have been recorded over the region 4000-400 cm⁻¹ and 3500-50 cm⁻¹. Both adrenaline and dopamine molecules belong to the Cs point group. A generalised set of symmetry coordinates has been constructed and hence, potential constants have been evaluated using Wilson’s F-G matrix method. Potential energy distribution has also been calculated for the normal modes of vibration to check whether the chosen set of vibrational frequencies contribute maximum to the potential energy associated with the normal coordinates of the molecule. <br/> <br/>Page(s): 884-892 Mon, 29 Oct 2007 22:58:59 GMT http://nopr.niscair.res.in/handle/123456789/2693 Title: Radon-thoron and their progeny dosimetry in the environment of LPG bottling plant using plastic track detectors <br/> <br/>Authors: Upadhyay, S B; Kant, K; Joshi, Rekha; Sonkawade, R G; Chakarvarti, S K; Sharma, G S <br/> <br/>Abstract: The inhalation dose rates and annual effective dose contribution from the mixed field of radon and thoron present in the environment of LPG bottling plant were measured, as it is very much essential from health and hygiene point of view of the workers in the plant. The radon and thoron concentration and the inhalation dose were found to vary from 7.78±2.02 to 59.01±5.57 Bq/m3, 1.16±0.28 to 65.08±5.09 Bq/m³ and 0.23 to 2.29 mSv/y, respectively. The concentration of radon daughters was found to vary from 0.84 to 6.38 mWL, the concentration of thoron daughters from 0.03 to 1.76 mWL, the annual exposure due to radon and thoron daughters, collectively, from 0.036 to 0.273 WLM, the life time fatality risk from 0.11 ×10⁻⁴ to 0.82 ×10⁻⁴ and the annual effective dose from radon and thoron (PAEC) from 0.14 to 1.06 mSv/y. <br/> <br/>Page(s): 880-883 Mon, 29 Oct 2007 22:58:59 GMT