Materials Literature
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Zinc oxide nanocrystallites down to 1.5 nm in diameter were made by spray combustion of Zn/Si precursors. These crystallites exhibit a quantum size effect: blueshift of light absorption with decreasing crystallite size. X-ray diffraction, high-resolution transmission electron microscopy, and nitrogen adsorption showed…
We report on a theoretical study of dc transport coefficients in (Ga,Mn)As diluted magnetic semiconductor ferromagnets that accounts for quasiparticle scattering from ionized Mn2+ acceptors with a local moment S=5/2 and from nonmagnetic compensating defects. In metallic samples Boltzmann transport theory with golden r…
A tris(3-pyridyl)-substituted C3 symmetric subphthalocyanine (SubPc) was dimerized into a M3L2 cage in the presence of a stoichiometric amount of (en)Pd(NO3)2. NMR studies demonstrated the recognition event to be accompanied by chiral self-discrimination between the two enantiomers of the SubPc. Moreover, the specific…
We analize electrical conductivity controlled by hopping of bound spin polarons in disordered solids with wide distributions of electron energies and polaron shifts (barriers). By means of percolation theory and Monte Carlo simulations we have shown that in such materials at low temperatures, when hopping occurs in th…
I calculate the quantum states for He atom in the potential of an external groove of the single-wall carbon nanotube bundle. The calculated ground-state energy is found to be in fair agreement with the experimental estimate which suggests that the outer groove site is a preferential site for the adsorption of He gas i…
It is shown that in polar geometry and normal incidence the 2x2 matrix technique - as discussed in detail in a preceeding paper [Phys. Rev. B 65, 144448 (2002)] - accounts correctly for multiple reflections and optical interferences, and reduces only in the case of a periodic sequence of identical layers to the Fresne…
We have examined polycrystalline MgB2 by electron energy loss spectroscopy (EELS) and density of state calculations. In particular, we have studied two different crystal orientations, [110] and [001] with respect to the incident electron beam direction, and found significant changes in the near-edge fine-structure of…
We study spin-dependent interband resonant tunneling in double-barrier InAs/AlSb/ GaMnSb heterostructures. We demonstrate that these structures can be used as spin filters utilizing spin-selective tunneling of electrons through the light-hole resonant channel. High densities of the spin polarized electrons injected in…
Surface effects on the electronic energy loss of charged particles entering a metal surface are investigated within linear-response theory, in the framework of time-dependent density functional theory. Interesting phenomena occur in the loss spectra originated by the boundary (bregenzung) effect, which is as a consequ…
A discrete model for the sintering of polydisperse, inhomogeneous arrays of cylinders is presented with empirical contact force-laws, taking into account plastic deformations, cohesion, temperature dependence (melting), and long-time effects. Samples are prepared under constant isotropic load, and are sintered for dif…
We report temperature and field dependent measurements of the magnetic susceptibility, specific heat and resistivity of sintered YbB2 pellets, prepared via two distinct reaction routes, utilizing different temperatures, pressures and sintering times. Sample behavior is affected by the preparation procedure, as a conse…
In this paper, a recently developed analytical equation of state (EOS) is used to investigate the bulk modulus of compressed liquid cesium and to locate common compression factor and the bulk modulus quiescence point(s). This EOS is applied quick well to Na and Rb far from Tc. Bulk modulus of liquid cesium have two qu…
Attractive alternatives to conventional contrast agents for magnetic resonance imaging applications are the paramagnetic chemical exchange saturation transfer (CEST) agents based on saturation transfer (ST) to the solvent water resonance. The ratio of ST effects obtained upon irradiating Ln-coordinated water and amide…
A simple and efficient concept has been developed for the synthesis of pH-responsive molecular nanocarriers based on commercially available hyperbranched polymers. These dendritic core-shell architectures can encapsulate, transport, and selectively release polar guest molecules in an acidic environment (pH 3–6, see sc…
The thermodynamic properties and the morphology of syndiotactic polystyrene solid samples exposed to solvents (benzene and toluene) are investigated. It is shown that, as far as the melting properties are concerned, there is no significant difference between these samples and solution-cast samples. This suggests that…
The photoluminescence efficiency of InP nanocrystals prepared via the dehalosilylation reaction between indium chloride and tris-(trimethylsilyl)phosphine in mixtures of trioctylphosphine and trioctylphosphine oxide can be drastically improved by etching with fluorine compounds, as proposed several years ago by Micic…
We present density-functional theory for linear and nonlinear response functions using an explicit exponential parametrization of the density operator. The response functions are derived using two alternative variation principles, namely, the Ehrenfest principle and the quasienergy principle, giving different but nume…
We investigate the optical properties of spherical gold and silver clusters with diameters of 20 nm and larger. The light scattering spectra of individual clusters are measured using dark-field microscopy, thus avoiding inhomogeneous broadening effects. The dipolar plasmon resonances of the clusters are found to have…
X-ray photoelectron spectroscopy (XPS) investigations of supported nanoparticles smaller than 10 nm show a significant shift of the electron binding energy of core levels compared with the bulk values. In this work, such shifts were examined at differently supported and prepared gold nanoparticles for the 4f electron…
A major challenge to increasing bandwidth in optical telecommunications is to encode electronic signals onto a lightwave carrier by modulating the light up to very fast rates. Polymer electro-optic materials have the necessary properties to function in photonic devices beyond the 40-GHz bandwidth currently available.…