Materials Literature
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The dynamical-mean-field theory combined with the noncrossing approximation is used to set up a scheme to study the electronic structure of strongly correlated electron systems. The noninteracting band structure is obtained from a density-functional calculation within the local-density approximation. With this method…
The dynamic mechanical properties of an organic hybrid consisting of chlorinated polyethylene (CPE) and N,N-dicyclohexyl-2-benzothiazolyl sulfenamide (DZ) were investigated. All the CPE/DZ hybrids showed a single loss tangent (tan δ) peak in the mechanical spectra. The peak area under the tan δ/temperature curves arou…
Immer größere expandierte Porphyrinoide (ein Beispiel ist gezeigt) werden durch neue Synthesemethoden zugänglich. Diese nichtaromatischen Verbindungen enthalten bis zu 16 konjugierte Pyrrolringe, zeigen eine neuartige Metallkoordination, sind chiral und können Anionen binden.
We have studied the quasibinary ferromagnetic semiconductor (Ga0.98Mn0.02)As by magnetic circular dichroism in x-ray absorption. We find a richly structured Mn absorption spectrum typical for localized 3d electrons. An analysis of the magnetization-averaged and dichroism line shapes shows a local Mn moment of 4.6μB, w…
We report computer simulation results of free energies of proton-disordered hexagonal ice and liquid water at atmospheric pressure with the 4-site transferable intermolecular potential model of water. A new reference system is used to calculate the free energy of the ice phase. The melting point of proton-disordered h…
Low-coverage adsorption isotherms for ${\mathrm{CH}}_{4}$ on single-walled carbon nanotube bundles have been measured at eight temperatures between 155 and 195 K. The nanotubes used in this study were untreated, so that the tubes have closed ends. The isosteric heat of adsorption was determined from the isotherms and,…
NdSc 3 ( BO 3 ) 4 (NdSB) can be grown as a nonlinear optical crystal having hexagonal (huntite) structure. The crystal has important spectroscopic properties suitable for various applications in photonics. The observed crystal-field splitting of the energy levels of Nd3+(4f3) has been identified based on analyses of t…
We have experimentally studied the mechanism of reentrant metal-insulator-metal transition of DCNQI-Cu system. Measurements of specific heat and latent heat were carried out by thermal relaxation (0.5< T <40 K), adiabatic pulse (20< T <100 K) and Differential Thermal Analysis (DTA) methods on samples under various che…
Verbrückende Methylengruppen werden in terminale Methylgruppen überführt, wenn periodisch mesoporöse Methylensilicate, die erstmals durch Tensid-Templat-Synthese hergestellt wurden, unter kontrollierten Bedingungen (350–600°C) getempert werden. Die Methylengruppen, die zunächst Bestandteil der Kanalwände sind, werden…
Two emission bands were simultaneously observed in iron-passivated porous silicon and their peak energies were in good agreement with the first two gap energies calculated for silicon nanocrystallites $(nc\ensuremath{-}\mathrm{Si}).$ This result indicates the existence of separate conduction subbands caused by the qua…
We have developed a calculational method for ligand-field multiplets. In our method the effect of the perturbations surrounding the considered atom is described by a monoelectronic potential interacting with the external electrons and the Hamiltonian is obtained by summing all the intra-atomic interactions and the ext…
The linear viscoelastic properties of polystyrene polyethylene (PS/PE) blends have been investigated in the molten state. For concentrations of the dispersed phase equal to 30 vol %, the blends exhibited a droplet-matrix morphology with a volume-average diameter of 5.5 μm for a 70/30 PS/PE blend at 200 °C and 14.7 μm…
Three series of thermotropic liquid crystalline polycarbonates and poly(ester-carbonate)s were prepared by solution polycondensation of 4,4′-biphenyldiol (BP), 4′-hydroxybiphenyl-4-hydroxybenzoate (HHB), or 4-hydroxyphenyl-4″-hydroxybiphenyl-4′-carboxylate (HHBP), as mesogenic unit, with 1,10-bis(p-hydroxybiphenoxy)de…
The cavitation inception process in trailing vortices has been studied for several years. One of the important findings from these studies is the strong sensitivity to nuclei size and number as well as significant viscous effects. In order to understand the nucleation and bubble growth process in more detail, a photog…
Equations are solved to give the variations in temperature, density, and potential, when a solid has electrical currents, heat currents, and particle diffusion. Solutions are presented in one dimension for currents down a bar. These solutions are used to calculate the efficiency of a thermoelectric refrigerator, which…
Biexcitons localized in ultrathin CdS/ZnS single quantum wells with fluctuating well thicknesses are investigated by two-photon absorption and single-exciton spectroscopy. For the binding energy of the confined biexciton, a value of $\ensuremath{\Delta}{E}_{\mathrm{B}}=38$ meV is determined. Comparing $\ensuremath{\De…
The local structure around Al and P impurities in silica is investigated using density-functional theory. Two distinct cases are considered: impurities substituting for a Si atom in $\ensuremath{\alpha}$ quartz, and impurities implanted in a stoichiometric $\ensuremath{\alpha}$-quartz crystal. Both impurity elements a…
The catalytically active copper phase for the partial oxidation of methanol is studied by means of time-resolved extended X-ray absorption fine structure (EXAFS) spectroscopy combined with the detection of the catalytic turnover. It is found that the active form of the copper is a strained nanocrystalline form of the…
Elastic methods are presently being used to study the space charge distributions in insulators. They are limited in their interpretation to simple geometries whereas real systems often involve complex structures such as the case for divergent electric field regions. The authors propose a general theory for the interpr…
We show that a cylindrical quantum wire whose lateral surface is deformed may support surface states localized on the deformation. This surface localization can be studied upon writing the single-particle Schr\"odinger equation in a curvilinear coordinates system on the surface. The energies of these localized states…