Materials Literature
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Polyoxoanions have enormous potential as drug delivery hosts, as catalysts, as agents for sequestering nuclear waste heavy metals, and as luminescent materials for laser and optical devices applications. We report the encapsulation of the polyoxoanion [Eu(H 2 O) 3 (α-1- P 2 W 17 O 61 )] 7- within Mobil crystalline mat…
The adsorption and oxidation reaction of CO on γ-Al 2 O 3 single-crystal thin films with Au nanoparticles were studied as a function of the particle size using reflection−adsorption infrared spectroscopy, temperature-programmed desorption (TPD), and the molecular beam technique in a temperature range of 93 K < T s < 2…
The symmetry adapted cluster (SAC)/SAC-configuration interaction method was applied to calculate the ground and excited states of zinc porphyrin monomers (without and with phenyl groups, ZnP and ZnPPh, respectively) and meso–meso linked (Zn2PMM) and doubly fused (Zn2PDF) zinc porphyrin dimers. Various features of the…
We present a study of the ambient and low-temperature dynamics on a single-crystalline sample of ${\mathrm{NbSe}}_{3}$ using meV-resolution inelastic x-ray scattering. Two phonon branches (LA, ${\mathrm{TA}}_{1})$ propagating along the system's quasi-one-dimensional direction ${b}^{*}$ have been determined. The low-te…
Annealing of sPP after a rapid quench from the melt to a temperature below T g (−3 °C) leads for an annealing temperature T c = 0 °C to a trans-rich mesomorphic phase, for T c = 25 °C to the helical crystalline phase, and for T c = 2 °C to a mixture of both phases. SAXS experiments show that the layer thickness and th…
An efficient synthetic route to fuse [5]helicene moieties around the phthalocyanine core is reported. The helicene moiety was constructed by the Diels-Alder reaction of 3,4,3',4'-tetrahydro-1,1'-dinaphthyl and dibromobenzyne. Subsequent cyanation, oxidation, O-alkylation, and cyclic tetramerization resulted in octaalk…
Abstract Self‐doped poly(aniline‐ co ‐aminonaphthalene sulfonic acid) (PANI‐ANSA) was synthesized by the copolymerization of 5‐aminonaphthalene‐2‐sulfonic acid (ANSA) and aniline. Scanning electron microscopy and transmission electron microscopy showed that the morphology of PANI‐ANSA synthesized at a high molar ratio…
SiO 2 thin films on Mo(112) have been characterized using metastable impact electron and ultraviolet photoelectron spectroscopies (MIES and UPS). The electronic properties of SiO 2 thin films with a thickness of 0.7−0.8 nm are identical to those of bulk SiO 2 . For defective SiO 2 surfaces prepared by three different…
Radiative lifetime, polarization, and the global Stokes shift of colloidal CdSe quantum rods with aspect ratios from 1.9 to 3.8 are measured at room temperature. The radiative lifetime and the global Stokes shift show nonmonotonous dependence on the aspect ratio of the nanorods, and strong linear polarization in emiss…
Getting all steamed up: The active phase formed in situ in the catalytic hydrolysis of chlorinated compounds, such as CCl4, at relatively low temperatures consists of a lanthanide oxide chloride, as evident from vibrational frequencies at 125, 188, 215, 335, and 440 cm−1 in the Raman spectrum (see picture). This activ…
A polymer scaffolding model is proposed to describe the electro-optic performance parameters of holographic polymer-dispersed liquid crystals (H-PDLC). Using a simple phenomenological approach to model the interaction between the liquid crystal and polymer scaffolding, the observed increase in critical field and reduc…
We have designed and fabricated spin superlattices composed of three kinds of perovskite oxides: ferromagnetic La0.6Sr0.4MnO3 (LSMO) sandwiched by two nonmagnetic insulators, SrTiO3 (STO), and LaAlO3 (LAO). Conventional superlattices, structured as alternating stack of two components, preserve centrosymmetry. By stack…
The dielectric response of semiconducting carbon nanotubes is studied within a tight-binding theory. We focus on “zigzag” tubes, finding that the induced charge exhibits large oscillations within the unit cell. The spatial extent of the response function is roughly equal to the nanotube radius, for any radius. We poin…
Aggregation properties of meso -tetratolylporphyrins bearing cationic substituents of a lipophilic nature such as ammonium, pyridinium, phosphonium, sulfonium, and isothiouronium were studied by UV/vis and resonance light scattering spectroscopy. The exciton point−dipole approximation was used to predict the structura…
The chirality of the ligand determines the nature of the helix: Coordination of a chain of [15]metallacrown-5 complexes based on phenylalanine hydroxamic acid results in an amphiphilic metallohelix with a 41 screw axis. The use of the L isomer of the acid gives the right-handed helix (see left structure) while the D i…
Die Welt ist klein! Eine neue Klasse von Einkristall-Nanodrähten auf Lanthanoidhydroxid-Basis konnte durch Hydrothermalsynthese erschlossen werden (Beispiel siehe Bild). Durch Änderungen des chemischen Potentials und des pH-Werts lassen sich Größe und Eigenschaften der Materialien gezielt beeinflussen. Eine von vielen…
Pt /( Ba 0.7 Sr 0.3 ) TiO 3 ( BST )/ YBa 2 Cu 3 O 7−x ( YBCO ) capacitors on SrTiO3 substrates were fabricated, and the temperature dependence of their current–voltage characteristics was studied in the temperature range from 100 to 300 K. It was found that the leakage current strongly depends on the voltage polarity…
Unter Strom: Die Tieftemperaturzüchtung von Ge-Nanodrähten gelang durch chemische Abscheidung von GeH4 auf ein mit Au-Nanopartikeln beschichtetes SiO2-Substrat (siehe Bild). Diese Technik, die die Synthese von Einkristall-Nanodrähten unter mildesten Bedingungen ermöglicht, kann auch für die Strukturbildung auf vorgemu…
Erbium-doped TiO2 (TiO2:Er) thin films with the anatase structure have been prepared on Si substrate by laser ablation. Sharp and intense Er-related emission in the visible region as well as in the IR region has been observed under over-band-gap excitation. The broad photoluminescence (PL) peaking at about 530 nm newl…
Ja, W@Au12 ist ikosaedrisch! Hier wird die experimentelle Bestätigung dieser vor kurzem postulierten neuen Klasse von Gold-Clustern gegeben. Durch Anionen-Photoelektronen-Spektroskopie und relativistische Dichtefunktionalrechnungen wird gezeigt, dass sowohl W@Au12 als auch Mo@Au12 hochstabile, ikosaedrische Cluster mi…