Radiative transfer in silylidene molecule

In order to search for silylidene (H2CSi) in the interstellar medium, Izuha et al. (1996) recorded microwave spectrum of H2CSi in laboratory and made an unsuccessful attempt of its identification in IRC +10216, Ori KL, Sgr B2, through its 717-616 transition at 222.055 GHz. For finding out if there are other transitions of H2CSi which may help in its identification in the interstellar medium, we have considered 25 rotational levels of ortho-H2CSi connected by collisional transitions and 35 radiative transitions, and solved radiative transfer problem using the LVG approximation. We have found that the brightness temperatures of 919-818, 918-817, 101,10-919, 1019-918, 111,11-101,10, 111,10-1019 and 121,12-111,11 transition are larger than that of 717-616 transition. Thus, these transitions may help in detection of H2CSi in the interstellar medium

Remote sensing of D-region ionosphere using multimode tweeks

Lightning discharges radiate electromagnetic waves in a wide frequency range, with maximum energy in extremely low frequency/very low frequency band. A part of the radiated extremely low frequency/very low frequency wave energy is trapped in the Earth–ionosphere waveguide and travels thousands of kilometers in different modes with lower attenuation. Amplitude, frequency and phase of these waves are used to study the less explored D-region ionosphere at lower latitudes. Extremely low frequency/very low frequency observations are recorded continuously by automatic whistler detector setup installed at low-latitude Indian station Lucknow (Geom. lat. 17.6 ° N; long. 154.5 ° E). In total, 149 cases of tweeks having modes ranging from 3 to 6 have been recorded by automatic whistler detector during December 2010 and analyzed. Result shows that the propagation distance in the Earth–ionosphere waveguide lies between 1.1 and 9.4 Mm. The electron density in the lower D-region varies between 25 and 150 cm - 3 . The upper boundary of the waveguide varies between 80 and 95 km. The reported results are in good agreement with the earlier measurements at different latitudes and longitudes

Ab-initio studies of the structural, electronic, optical and magnetic properties of DyMg intermetallic compound

Structural, electronic, optical and magnetic properties of DyMg intermetallic compound are calculated by using the full potential linearized augmented plane wave (FP-LAPW) method employing density functional theory (DFT). The obtained optimized equilibrium lattice constant in stable structure of DyMg (B2 phase) with spin polarized calculations is 7.107 Bohr and that without spin polarized calculations is 7.115 Bohr. The electronic band structure and density of states plots show metallic character of DyMg. The energy-dependent components of dielectric function, refractive index, extinction coefficient, absorption spectra, optical conductivity, energy loss spectra and reflectivity are reported in the energy range 0–20 eV. In DyMg maximum absorption is observed in the range 4–11 eV. The highest optical conductivity peak is observed near 0.78 eV (1589.5409 nm) and maximum energy loss occurs at 11.90 eV which corresponds to ~2.8 Hz in ultraviolet region. The obtained total magnetic moment shows that its value decreases with the increase in lattice parameter. Keywords: Magnesium alloy, Rare-earth elements, Density functional theory, Band structure, Optical properties, Magnetic propertie

Full potential study of HoMg

In this paper, HoMg is studied in two different phases i.e. B1 and B2. The calculated lattice constants in B1 and B2 phases are 6.39 Å and 3.78 Å and corresponding energies are −25,648.49 Ry and −25,648.56 Ry, respectively. It is more stable in B2 phase (Pm-3m configuration with no. 221). The analysis of the obtained band structure and density of states shows metallic character of HoMg. Detailed information about the elastic properties is also presented in this paper. The calculated values of Cauchy pressure, G/B and Poisson ratio are −10.72, 0.58 and 0.26, respectively which indicates that HoMg have brittle character. Calculations for the optical spectra such as the components of dielectric function, refractive index and other parameters of the optical properties are performed in the energy range of 0–20 eV. For HoMg, the main peak of absorption spectra and energy loss function is located at 7.44 eV and 11.76 eV, respectively. Thermal parameters such as Gruneisen parameter, Debye temperature, Specific heat etc. have been reported as a function of pressure and temperature. Keywords: Rare-earth magnesium alloy, DFT, Elastic properties, Optical and thermal propertie

Inorganic Photovoltaics - Planar and Nanostructured Devices

Since its invention in the 1950s, semiconductor solar cell technology has evolved in great leaps and bounds. Solar power is now being considered as a serious leading contender for replacing fossil fuel based power generation. This article reviews the evolution and current state, and potential areas of near future research focus, of leading inorganic materials based solar cells, including bulk crystalline, amorphous thin-films, and nanomaterials based solar cells. Bulk crystalline silicon solar cells continue to dominate the solar power market, and continued efforts at device fabrication improvements, and device topology advancements are discussed. III-V compound semiconductor materials on c-Si for solar power generation are also reviewed. Developments in thin-film based solar cells are reviewed, with a focus on amorphous silicon, copper zinc tin sulfide, cadmium telluride, as well as nanostructured Cadmium telluride. Recent developments in the use of nano-materials for solar power generation, including silicon and gallium arsenide nanowires, are also reviewed