Materials Literature
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In der Kürze liegt die Würze: Die nichtaromatische freie Base 6,16-Dimesityl-11-phenylsubpyriporphyrin, verwandt mit Triphyrin(1.1.1), enthält eine dreizentrige Wasserstoffbrücke. Laut Röntgenstrukturanalyse hat diese Verbindung den kleinsten bekannten N⋅⋅⋅N-Abstand (2.370 Å) zweier N-Atome, die an einer Wasserstoffbr…
Fullerene derivatives bearing long alkyl chains epitaxially adsorb on the basal plane of graphite forming well-ordered one-dimensional lamellae. Within the lamellae, the C60 moieties are organized in a zigzag-type fashion. The ordering is mainly governed by the substitution pattern and chain length of the alkyl chains…
The formation of clusters in condition of thermodynamic equilibrium can be easily observed both in two and three dimensions. In two dimensions relevant cases include pattern formation in Langmuir monolayers and ferrofluids, while in three dimensions cluster phases have been observed in colloids and in protein solution…
Periodic patterning on one-dimensional (1D) carbon nanotubes (CNTs) is of great interest from both scientific and technological points of view. In this letter, we report using a facile physical vapor deposition method to achieve periodic polyethylene (PE) oligomer patterning on individual CNTs. Upon heating under vacu…
Short and to the point: A three-centered hydrogen bond is present in 6,16-dimesityl-11-phenylsubpyriporphyrin, a non-aromatic free-base triphyrin(1.1.1)-related molecule. X-ray crystal structural analysis shows this compound contains the shortest known N⋅⋅⋅N distance (2.370 Å) for two N atoms involved in hydrogen bond…
The electronic properties of porphyrin zinc aggregates wired using single-walled carbon nanotubes (SWNTs) are described. A self-assembled structure is formed by casting a solution of SWNTs and 5,15-bispentylporphyrinato zinc(II) (BPP-Zn) onto a substrate (see figure). Rectifying behavior has been observed at SWNT/BPP-…
Stimuli-responsive polymer brushes with adsorbed fluorescent semiconductor nanocrystals can be used in solvent-sensitive sensors based on the fluorescence-interference contrast (see figure) of semiconductor nanocrystals near a reflecting silicon surface. The reversible, solvent-depending swelling of a thin, surface-an…
Raman scattering experiments on ${\mathrm{Na}}_{x}{\mathrm{CoO}}_{2}\ifmmode\cdot\else\textperiodcentered\fi{}y{\mathrm{H}}_{2}\mathrm{O}$ single crystals show a broad electronic continuum with a pronounced peak around $100\text{ }\text{ }{\mathrm{cm}}^{\ensuremath{-}1}$ and a cutoff at approximately $560\text{ }\text…
Here, we investigate water-in-oil (W/O) emulsions that are stabilized by polystyrene latex particles with sulfate surface groups. The particles, which play the role of emulsifier, are initially contained in the disperse (water) phase. The existence of such emulsions formally contradicts the empirical Bancroft rule. Th…
The oxidation and reduction of Fe3O4-supported Pd nanoparticles is strongly size-dependent and implies that the oxidation mechanism is controlled by the metal oxide interface. Molecular beam experiments and scanning tunneling microscopy indicate that this size dependence gives rise to a pronounced maximum of the oxyge…
Orthorhombic V(2)O(5) single-crystalline nanobelts with widths of 100-300 nm, thicknesses of 30-40 nm, and lengths up to tens of micrometers have been synthesized on a large scale in a hydrogen peroxide aqueous solution by an environmentally friendly chemical route. Such nanobelts grow along the direction of [010]. Th…
Semiconductor nanowires exhibit large polarization anisotropy for the absorption and emission of light, making them ideal building blocks for novel photonic metamaterials. Here, we demonstrate that a high density of aligned nanowires exhibits giant optical birefringence, a collective phenomenon observable uniquely for…
We show that the piezoelectric effect that describes the emergence of an electric field in response to a crystal deformation in III-V semiconductors such as GaAs and InAs has strong contributions from second-order effects that have been neglected so far. We calculate the second-order piezoelectric tensors using densit…
Hierarchical micro- and nanostructures can be produced simultaneously by the novel layer-by-layer assembly described here. The multilayer films, grown by an exponential growth mechanism that can be amplified by adding silver ions, showed extreme hydrophobicity and a lotus-leaf-like amplification of the surface roughne…
Nanoparticles (dia ~ 5 - 7 nm) of Bi_0.5 X_0.5(X=Ca,Sr)MnO_3 are prepared by polymer assisted sol-gel method and characterized by various physico-chemical techniques. X-ray diffraction gives evidence for single phasic nature of the materials as well as their structures. Mono dispersed to a large extent, isolated nanop…
We present a time-resolved measurement of magnetization dynamics during ferromagnetic resonance (FMR) in a single layer of Ni81Fe19. Small-angle (<1 deg.) precession of elemental Ni, Fe moments could be measured directly and quantitatively using time-resolved x-ray magnetic circular dichroism (XMCD) in transmission. T…
Novel "green" composites were successfully fabricated from recycled cellulose fibers (RCF) and a bacterial polyester, poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) by melt mixing technique. Various weight contents (15%, 30%, and 40%) of the fibers were incorporated in the PHBV matrix. The effect of the fiber wei…
We propose an effective permittivity model to homogenize an array of long thin epsilon-negative rods arranged in a periodic lattice. It is proven that the effect of spatial dispersion in this electromagnetic crystal cannot be neglected, and that the medium supports dispersionless modes that guide the energy along the…
The onset of a Griffiths-like phase has been observed in ${\mathrm{Tb}}_{5}{\mathrm{Si}}_{2}{\mathrm{Ge}}_{2}$ (${T}_{C}=110\text{ }\text{ }\mathrm{K}$) by means of magnetic susceptibility and small-angle neutron scattering experiments. We show the growth of a ferromagnetic cluster system characterized by an inverse s…
Intense theoretical and experimental interest has been focused on the possibility of new materials with hardness exceeding that of diamond. However, building the link between the information that first-principles calculations can produce and the hardness of materials remains one of the challenges of computational mate…