Materials Literature
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A new formulation of the weighted density approximation, the so-called modified weighted density approximation (MWDA), has been developed recently by Denton and Ashcroft [Phys. Rev. A39, 4701 (1989)]. In the present article, the MWDA theory is examined by applying it to the freezing of simple liquids in low dimensions…
A semiempirical many-body potential [J. Tersoff, Phys. Rev. Lett. 61, 2879 (1988)] has been used to model carbon clusters (${\mathit{C}}_{\mathit{n}}$) in the size range 50\ensuremath{\le}n\ensuremath{\le}72. Ground-state geometries are identified by simulated annealing. Our results show that, for these sizes, all the…
An angle-resolved high-resolution electron-energy-loss-spectroscopy study is reported of the surface-plasmon spectrum on Ag(001) along different azimuths. A single loss energy is observed which disperses linearly with exchanged momentum ${\mathit{q}}_{\mathrm{?}}$ from 3.69\ifmmode\pm\else\textpm\fi{}0.01 eV with a sl…
A Fibonacci optical superlattice is analyzed which is made from a single crystal with quasiperiodic laminar ferroelectric domain structures. The second-harmonic generation in this system is studied. Because of the dispersive effect of the refractive index, the second-harmonic spectrum does not reflect the symmetry of…
The adsorption and desorption kinetics for SiCl4 on Si(111)7×7 were studied using laser-induced thermal desorption (LITD) and temperature programmed desorption (TPD) techniques. TPD experiments monitored SiCl2 as the desorption product at approximately 950 K using a heating rate of β=9 K/s. SiCl2 was also observed as…
Cristallisation dans Cmca avec a=13,215, b=5,943, c=5,938 A, z=4; affinement jusqu'a R=0,017. La structure est constituee de couches infinies d'antisprismes carres de LaO 4 S 4 , qui sont connecte entre eux par leurs aretes. Ces couches, paralleles a (100), ont en commun un oxygene ou un plan de disulfure. Les liaison…
A new route of preparation of high quality of graphitized films has been demonstrated. Highly graphitized films with electrical conductivity as high as 6×103 S/cm have been prepared by pyrolysis of bacterial cellulose films at 2900 °C. These films can be well intercalated with acceptors and donors such as FeCl3 and K,…
The optical transmission spectra of rf sputtered tungsten oxide films on glass substrates were modeled to determine absorption edge behavior, film thickness, and index of refraction. Removal of substrate reflection and absorption phenomena from the experimental spectra allowed direct examination of thin film optical c…
We present the results of comprehensive measurements of photoconductivity in films of poly(3-hexylthiophene-2,5-yl), a soluble alkyl derivative of polythiophene. Transient measurements in the subnanosecond-time regime reveal a fast, temperature-independent photoconductive response which decays within about 100 ps afte…
C 18 H 36 O 2 cristallise dans P2 1 /a avec a=5,603, b=7,360, c=50,789 A, β=119,40 o , Z=4; affinement jusqu'a R=0,052. La chaine de polymethylene prend une conformation tout-trans et constitue une sous-maille de type 01 avec a s =7,36, b s =5,02, c s =2,55 A. Cet axe a s est parallele a l'axe b et l'axe c s forme un…
One- and two-dimensional simulations have been used to explore the effects of the Eley–Rideal process CO+OS→CO2+S on a simple model for the catalytic oxidation of carbon monoxide by oxygen. In this model, CO and O2 are fed to the surface (lattice) to form the adsorbed species COS and 2OS. The addition of CO is assumed…
The results of canonical ensemble molecular dynamics calculations of mixtures of Lennard–Jones and Stockmayer fluids are reported. To study solely the influence of the polarity, the Lennard-Jones parameters were identical for both components. The excess mixing properties show a strong asymmetry with respect to composi…
Structure analysis of K 3 H(SO 4 ) 2 was performed by X-ray diffraction experiments in order to study the hydrogen bond character in connection with the geometrical isotope effect. Crystal data at room temperature were obtained as a=9.777(1)Å, b=5.674(1)Å, c=14.667(4)Å, β=102.97(2)° and the space group A 2/ a , Z =4.…
We present a theoretical study of the lamellar structure of diblock copolymers blended with neutral solvent. The calculations are based on numerical solutions of the equations of the mean field self-consistent theory of incompressible polymer/solvent blends, from the weak through to the strong segregation limits. For…
A self-consistent continuum model is presented for glow discharges based on the moments of the Boltzmann transport equation. The resultant set of governing equations consist of continuity and momentum equations for electrons and ions, an energy conservation equation for electrons and Poisson’s equation. An efficient n…
The deposition of diamond films by microwave plasmas has been studied in gaseous mixtures of methane, hydrogen, and noble gases. Plasma diagnostic results are compared with growth rates and Raman spectra of the films. The noble gases, which influence the degree of excitation or reactant molecules by energy transfer or…
Optical transmission through binary multilayers arranged according to deterministic aperiodic distribution rules is investigated using an extension of the trace-map technique. It is proven that in order to get a complete description of this ideal experiment, the usual trace map must be combined with a so-called ``anti…
The Raman spectrum of sodium tetrasilicate (Na2Si4O9) glass has been obtained as a function of pressure at 298 K to approximately 50 GPa. The scattering intensity of bands associated with silica tetrahedra containing nonbridging oxygens (Q3 species) decreases with increasing pressure and these bands are absent above 2…
${\mathrm{VO}}_{2}$ single crystals were studied in an effort to resolve the differences that are present in two previous reports on the Raman spectra of ${\mathrm{VO}}_{2}$. We find that surface oxidation effects that change the stoichiometry of the material at the surface layer produce large shifting of the Raman sp…
The room-temperature ferromagnetic resonance (FMR) spectra of γ-Fe2O3, CrO2, and barium ferrite particulate magnetic recording tapes have been measured at microwave frequencies of 9.35 and 35 GHz for various orientations of the static and high-frequency magnetic fields with respect to the tape. For CrO2 tapes, the inf…