795 research outputs found
Structural, Morphological and Optical Parameters of Zn(1-x) CuxS Thin Films for Optoelectronic Devices
In the present work, ZnS and Cu incorporated at (2%, 4%,6%, 8%, and 10%) thin films were growth onto hot glass substrates at substrates temperature 270 oC with thickness about 100 nm by chemical spray pyrolysis technique. The solutions of the spray consists of Zn(CH3COO)2.2H2O, SC(NH2)2 and CuCl2.2H2O with molar concentration 0.1M/L. The structure of the film was studied by XRD pattern, the results shows that the films were polycrystalline with cubic phase for pure ZnS and hexagonal phase for Zn1-xCuxS at x=10%. The optical constants, refractive index, n and extinction coefficient, k were determined The optical energy gap of the direct transition is also estimated, pure ZnS is 3.42 eV, and it increases as the Cu concentration increases from 3.49 to 3.67 eV. The room temperature photoluminescence (PL) of copper-doped zinc sulfide (ZnS:Cu) nanoparticles was studied. Through Gaussian fitting, the PL spectrum of undoped ZnS nanoparticles is deconvoluted into two blue luminescence peaks (centered at 411 nm and 455 nm, respectively), both of which can be attributed to the recombination of ZnS defect states. But for doped samples, a third peak at about 500 nm was also identified. Discussed the changes of all optical constants and PL spectra from the changes of optoelectronics microstructure parameter
14-Bromo-12-chloro-2,16-dioxapentacyclohenicosa-3(8),10,12,14-tetraene-7,20-dione
In the title compound, C19H16BrClO4, both the fused xanthene rings and one of the cyclohexane rings adopt envelope conformations, while the other cyclohexane ring is in a chair conformation. In the crystal, molecules are linked by C-H...O hydrogen bonds, forming infinite chains running along [10-1] incorporating R22(16) ring motifs. In addition, C-H...[pi] interactions and weak [pi]-[pi] stacking interactions [centroid-centroid distance = 3.768 (3) Ã…] help to consolidate the packing
Optical Parameters of Varies Thickness of Bismuth (Iii) Iodide Thin Films for Photovoltaic and Nonlinear Applications
We report in varies thickness of BiI3 thin films by thermal evaporation techniques onto glass substrate. The films were strongly oriented along the (113) plane. The structural parameters of these films (crystallite size and lattice strain) were determined using (XRD) pattern. The thicknesses and refractive indices of the films were considered using Swanepoels method. The band gap was determined in terms of T and R spectrum in the UV-region of the absorption. The possible optical transitions of all films are found to be allowed direct transition with energy gap fluctuate bout 1.96 ± 2% eV. Dielectric constant, volume-energy-loss function (VELF) and surface-energy-loss function (SELF) for as deposited films were discussed in terms of film thickness rising. The change in optical parameters have been interpreted in terms of the change in microstructure parameters. BiI3 is recommended for photovoltaics and nonlinear optics because of its higher absorption coefficient, dielectric constant, and fair band gap
Particle-in-cell Simulations of the Parallel Proton Firehose Instability Influenced by the Electron Temperature Anisotropy in Solar Wind Conditions
In situ observations of the solar wind show a limited level of particle temperature anisotropy with respect to the interplanetary magnetic field direction. Kinetic electromagnetic instabilities are efficient to prevent the excessive growth of the anisotropy of particle velocity distribution functions. Among them, the firehose instabilities are often considered to prevent the increase of the parallel temperature and hence to shape the velocity distribution functions of electrons and protons in the solar wind. We present a nonlinear modeling of the parallel firehose instability, retaining a kinetic description for both the electrons and protons. One-dimensional (1D) fully kinetic particle-in-cell simulations using the energy conserving semi-implicit method (ECsim) are performed to clarify the role of the electron temperature anisotropy in the development of the parallel proton firehose instability. We found that in the presence of an electron temperature anisotropy, such that the temperature parallel to the background magnetic field is higher than the temperature in the perpendicular direction, the onset of the parallel proton firehose instability occurs earlier and its growth rate is faster. The enhanced wave fluctuations contribute to the particle scattering reducing the temperature anisotropy to a stable, nearly isotropic state. The simulation results compare well with linear theory. A test case of 1D simulations at oblique angles with respect to the magnetic field is also considered, as a first step to study the cumulative effect of protons and electrons on the full spectrum of instabilities
Sterile neutrino dark matter in extension of the standard model and galactic 511 keV line
Sterile right-handed neutrinos can be naturally embedded in a low scale
gauged extension of the standard model. We show that, within a low
reheating scenario, such a neutrino is an interesting candidate for dark
matter. We emphasize that if the neutrino mass is of order of MeV, then it
accounts for the measured dark matter relic density and also accommodates the
observed flux of 511 keV photons from the galactic bulge.Comment: 10 pages, 1 figure, references added, final version appeared in JCA
Supersymmetric contributions to the CP asymmetry of the B --> phi K and B --> eta' K
We analyse the CP asymmetry of the B --> phi K and B --> eta' K processes in
general supersymmetric models. We consider both gluino and chargino exchanges
in a model independent way by using the mass insertion approximation method. We
adopt the QCD factorization method for evaluating the corresponding hadronic
matrix elements. We show that chromomagnetic type of operator may play an
important role in accounting for the deviation of the mixing CP asymmetry
between B --> phi K and B --> J/psi K processes observed by Belle and BaBar
experiments. We also show that due to the different parity in the final states
of these processes, their supersymmetric contributions from the R-sector have
an opposite sign, which naturally explain the large deviation between their
asymmetries.Comment: Invited review article for Mod. Phys. Lett. A. 12 pages, 5 figures. 2
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Sect and House in Syria: History, Architecture, and Bayt Amongst the Druze in Jaramana
This paper explores the connections between the architecture and materiality of houses and the social idiom of bayt (house, family). The ethnographic exploration is located in the Druze village of Jaramana, on the outskirts of the Syrian capital Damascus. It traces the histories, genealogies, and politics of two families, bayt Abud-Haddad and bayt Ouward, through their houses. By exploring the two families and the architecture of their houses, this paper provides a detailed ethnographic account of historical change in modern Syria, internal diversity, and stratification within the intimate social fabric of the Druze neighbourhood at a time of war, and contributes a relational approach to the anthropological understanding of houses
CP violation in supersymmetric model with non-degenerate A-terms
We study the CP phases of the soft supersymmetry breaking terms in
string-inspired models with non-universal trilinear couplings. We show that
such non-universality plays an important role on all CP violating processes. In
particular these new supersymmetric sources of CP violation may significantly
contribute to the observed CP phenomena in kaon physics while respecting the
severe bound on the electric dipole moment of the neutron.Comment: 14 pages, Late
Delayed presentation of an isolated gallbladder rupture following blunt abdominal trauma: a case report
This is an Open Access article distributed under the terms of the Creative Commons Attribution Licens
Present and Future CP Measurements
We review theoretical and experimental results on CP violation summarizing
the discussions in the working group on CP violation at the UK phenomenology
workshop 2000 in Durham.Comment: 104 pages, Latex, to appear in Journal of Physics
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