Materials Literature
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Hydrophobe Wechselwirkungen wurden für die Selbstorganisation von Azofarbstoffen und Makrocyclen zu den stabilen Rotaxanen 1 genutzt. Eingeschlossen von α‐Cyclodextrin, β‐Cyclodextrin oder einem Cyclophan, wurden die hantelförmigen Azofarbstoffe durch Azokupplung im wäßrigen Medium synthetisiert. magnified image
Photochemical switches, energy storage devices, or photochemical sensors are potential applications of luminescent gold complexes. The basis for this expectation is the spectacular discovery by Balch et al., who observed that a trinuclear gold complex (see picture) gave rise to an intense emission upon dissolution in…
We have investigated the interaction of Pt with single-crystal SrTiO3(001) and polycrystalline Ba0.7Sr0.3TiO3 thin films using photoemission spectroscopies. Significant band bending is caused by interface formation, determining the Schottky barrier height. We have depth profiled the band bending for Ba0.7Sr0.3TiO3 thi…
Hexagonal strukturiertes, mesoporöses Platin (siehe Bild rechts) erhält man durch Reduktion von Platinsalzen in lyotropen Flüssigkristallphasen. Das Templat kann vom nanostrukturierten Metallkolloid entfernt werden, ohne daß dabei dessen Struktur zerstört wird. magnified image
The independent particle approximation is shown to break down for the photoionization of both inner and outer $n\ensuremath{\ell}$ $(\ensuremath{\ell}>0)$ electrons of all atoms, at high enough energy, owing to interchannel interactions with the nearby $\mathrm{ns}$ photoionization channels. The effect is illustrat…
The thermal stability of the icosahedral phase (i phase) in Ti45Zr38Ni17 alloys is demonstrated. As-cast alloys containing initially only the C14 hexagonal Laves and α-solid-solution phases transformed primarily to the icosahedral phase upon annealing in vacuum for 64 h at 570 °C. This confirms previous evidence for i…
The fabrication of nanotube field emitters with an onset field as low as 0.8 V/μm is described and the low-field electron emission mechanism is discussed. These emitters are made using nanotube cathode deposit with the addition of epoxy resin. The preferred orientation of nanotubes in nanotube bundles of the deposit i…
We introduce a model where an isotropic, dynamically-imposed stress induces fracture in a thin film. Using molecular dynamics simulations, we study how the integrated fragment distribution function depends on the rate of change and magnitude of the imposed stress, as well as on temperature. A mean-field argument shows…
We consider the dynamics of freely translating and rotating diblock (A-B), Gaussian copolymers, in dilute solutions. Using the multiple scattering technique, we have computed the diffusion and the friction coefficients D_AB and Zeta_AB, and the change Eta_AB in the viscosity of the solution as functions of x = N_A/N a…
We use diffusing-wave spectroscopy to measure the motion of droplets in concentrated emulsions subjected to a periodic shear strain. The strain gives rise to periodic echoes in the correlation function which decay with increasing strain amplitude. For a given strain amplitude, the decay of the echoes implies that a fi…
Abstract Zeolites are viewed by some as the “philosopher's stone” of modern chemistry. [1] They are more or less indispensable in oil refining and petrochemicals manufacture where they are widely applied as solid acid catalysts. More recently attention has been focused on their use in the manufacture of fine chemicals…
Striking yellow luminescence is observed upon addition of a drop of solvent to colorless crystals of [Au3(CH3NCOCH3)3] that were previously irradiated with near-visible light. The trigonal prismatic stacking of individual molecules of the triangular cluster in the solid state (shown on the right) sheds light on the p…
We report the inducement of a ferromagnetic order by photogenerated carriers in a novel III-V--based magnetic semiconductor heterostructure $p$-(In,Mn)As/GaSb grown by molecular beam epitaxy. At low temperatures $(<35\mathrm{K})$, samples preserve ferromagnetic order even after the light is switched off, whereas th…
We have investigated the magnetic relaxation of clusters of eight iron ions characterized by a spin ground state of ten and an Ising anisotropy. Below 400 mK the relaxation rate is temperature independent suggesting that tunneling of the magnetic moment across its anisotropy energy barrier occurs. Using the anisotropy…
A giant magnetocaloric effect (ΔSmag) has been discovered in the Gd5(SixGe1−x)4 pseudobinary alloys, where x⩽0.5. For the temperature range between ∼50 and ∼280 K it exceeds the reversible (with respect to alternating magnetic field) ΔSmag for any known magnetic refrigerant material at the corresponding Curie temperat…
Structural studies of La 3 Ni 2 O 6.92 with a double layered perovskite structure have been performed by the X-ray Rietveld analyses between 300 K and 650 K. The interatomic distance between Ni and the apical oxygen (on the outside of NiO 2 double layer) rapidly increases around the phase-transition temperature T B ∼5…
We measured reflectance and transmittance spectra of epitaxial ${\mathrm{BaPb}}_{1\mathrm{\ensuremath{-}}\mathrm{x}}$ ${\mathrm{Bi}}_{\mathrm{x}}$${\mathrm{O}}_{3}$ (x=1.0, 0.8, and 0.6) thin films, prepared by pulsed-laser deposition. The measured spectra showed strong absorption in the frequency regions below direct…
The first-order Raman spectra of A g (1) , A g (2) + B g (2) and B g (1) modes in CaWO 4 crystal were measured in the temperature range of 77–771 K and the linewidths at these temperatures were obtained. The temperature dependence of the linewidths was analyzed using the phonon dispersion curves calculated on the basi…
Band-gap states in V-doped ${\mathrm{TiO}}_{2}$ have been studied by photoemission spectroscopy over a range of photon energies encompassing the Ti 3p and V 3p core thresholds. The states show resonant enhancement at photon energies significantly higher than found for Ti 3d states introduced into ${\mathrm{TiO}}_{2}$…
This paper reports on the p to n transition in Pb doped Se–In chalcogenide glasses. Measurements of thermoelectric power in the temperature range 300 K⩽T⩽315 K, dc conductivity in the temperature range 100⩽T⩽300 K, and optical band gap (Egopt) have been carried out for Se75In25−xPbx (x=0,5,10,15) samples. The p-n tran…