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Electronic Band Structure (electronic + band_structure)
Selected AbstractsChemInform Abstract: Ab initio Calculations of Electronic Band Structure and Charge Densities of Zinc Blende-Type GaN, BN and Their Solid Solution B0.5Ga0.5N.CHEMINFORM, Issue 51 2008Rabah Riane Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] Studies of electron transfer dynamics in particle-surface interactionsISRAEL JOURNAL OF CHEMISTRY, Issue 1-2 2005Vladimir A. EsaulovArticle first published online: 10 MAR 2010 A review of recent work on electron transfer processes leading to neutralization of positive ions and formation of negative ions is presented. Experiments were performed on simple jellium-like metal surfaces, transition metals, and specific characteristics of electronic band structure were investigated for some cases, revealing differences in electron transfer processes between surfaces of the same element. It was shown that electronegative adsorbates like oxygen and chlorine provoke strong changes in electron transfer rates, which are akin to promotion and poisoning of reactions at surfaces. The results of experiments on Auger neutralization of He+ ions on Ag surfaces and H, and F, formation on Ag and Pd surfaces are presented and compared with recent theoretical treatments of these processes. The effect of adsorbates is illustrated by the example of chlorine adsorption on silver. Directions where further theoretical effort would considerably advance the understanding of these phenomena are delineated. [source] Synthesis and Comparative Study of Nano-TiO2 Over Degussa P-25 in Disinfection of WaterPHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 3 2010S. Swetha Nanostructured TiO2 crystals were synthesized by gel to crystalline conversion. The crystals obtained were anatase form of titania averaging in 30 nm particles with an intrinsic band gap of 3.1 eV. The photocatalytic behavior was evaluated for the bactericidal effect in water, contaminated with the indicator organism Escherichia coli. The 100% photoinactivation of E. coli was achieved within 60 min with suspended nano-TiO2. The catalytic activity of synthesized nanosample was observed to be 2.6 times more than that of commercial TiO2 sample referred to as Degussa P-25. The photoinactivation of E. coli was tested with irradiation source of different wavelengths to substantiate the influence of particle size and nano crystallinity on electronic band structure. The photoactivity of nano titania enhanced to 1.625 times when the source of irradiation shifted from 360 to 400 nm while Degussa P-25 showed no change. [source] Theoretical resonant Raman spectra of nanotube (7,0) with point defectsPHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 11-12 2009Valentin N. Popov Abstract The Raman spectra of the nanotube (7,0) with point defects (monovacancy, divacancy, and Stone,Wales defect) were simulated in order to derive spectroscopic signatures of defective nanotubes. First, we calculated the electronic band structure and the phonon dispersion of the defective nanotubes using supercells within a non-orthogonal tight-binding model. We found that new optical transitions and Raman-active phonons appeared in comparison with the perfect nanotube. Secondly, we calculated the resonance Raman excitation profile for all Raman-active phonons of the defective nanotubes and simulated their Raman spectra at specific laser excitation energies. The predicted high-intensity Raman lines can be used as spectroscopic signatures of the defective nanotubes. [source] Low energy quasiparticle dispersion of graphite by angle-resolved photoemission spectroscopyPHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 11 2007A. Grüneis Abstract The low energy electron dispersion in graphite is measured by angle-resolved photoemission spectroscopy. The measured photoemission intensity maxima are compared to a tight-binding calculation of the electronic band structure. We observe a strong trigonal warping of the equi-energy contour which is well reproduced by the calculations. Furthermore we clearly show that the concept of Dirac Fermions breaks down for AB stacked graphite. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Isostructural BaSi2, BaGe2 and SrGe2: electronic and optical propertiesPHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 7 2007D. B. Migas Abstract We have performed a theoretical study of the electronic band structure, density of states, dielectric function and absorption coefficient of isostructural BaSi2, BaGe2 and SrGe2 compounds by means of different ab initio methods. All materials are found to be indirect band-gap semiconductors displaying almost equal dispersion of bands close to the gap region. The energy gaps of 0.83, 0.57 and 0.44 eV are estimated for BaSi2, BaGe2 and SrGe2, respectively. Analysis of the absorption coefficient of BaSi2 in comparison with data for other semiconducting silicides indicates its prospects for a solar cell application. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Oxygen induced band-gap reduction in ZnOxSe1,x alloysPHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 3 2004W. Shan Abstract The effect of alloying a small amount of ZnO with ZnSe on the electronic band structure has been studied. Optical transitions in MBE-grown ZnOxSe1,x epitaxial films (0 , x , 0.0135) were investigated using photoreflectance and photoluminescence spectroscopies. The fundamental band-gap energy of the alloys was found to decrease at a rate of about 0.1 eV per atomic percent of oxygen. The pressure dependence of the band gap was also found to be strongly affected by the O incorporation. Both effects can be quantitatively explained by an anticrossing interaction between the extended states of the conduction band of ZnSe and the highly localized oxygen states located at approximately 0.22 eV above the conduction band edge. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Tight binding modelling of electronic band structure in conventional InGaN/GaN and dilute GaAsN/GaAs nitride heterostructuresPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 2 2007H. Hakan Gürel Abstract We utilize a semi-empirical sp3s * tight binding model to investigate the strain and composition effects on electronic structure of conventional InGaN/GaN and dilute GaAsN/GaAs cubic nitride heterostructures. The model includes the second nearest neighbor (2NN) atomic interactions, spin-orbit splitting and nonlinear composition variation of atomic energies and bond lengths of ternaries. Results show that band gaps of conventional InGaN increase with composition for 0 < x < 1. However, the , band gap of dilute GaAsN decreases with composition for x < 0.25 and then starts to increase for 0.26 < x < 1. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Optical properties and structural phase transitions of lead-halide based inorganic,organic 3D and 2D perovskite semiconductors under high pressurePHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 14 2004K. Matsuishi Abstract Optical absorption, photoluminescence and Raman scattering of lead-halide based inorganic,organic perovskite semiconductors were measured under quasi-hydrostatic pressure at room temperature. For the 3D perovskite semiconductor, (CH3NH3)PbBr3, the free exciton photoluminescence band exhibits red-shifts with pressure, and jumps to a higher energy by 0.07 eV at 0.8 GPa, which is associated with a phase transition from a cubic to an orthorhombic structure confirmed by Raman scattering. Above the phase transition pressure, the exciton band shows blue-shifts with further increasing pressure, and eventually disappears above 4.7 GPa. The results are compared with those for the 2D perovskite semiconductor, (C4H9NH3)2PbI4. First principles pseudopotential calculations were performed to investigate changes in octahedral distortion and electronic band structures with pressure. The calculations have explained the origins of the intriguing changes in the electronic states with pressure in view of bonding characters between atomic orbitals in octahedra. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] | |||||||||||||