Materials Literature
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Laser irradiation of aqueous silver cations in the presence of a reducing agent induces growth of metallic silver particles. The picture shows a schematic illustration of a microscope setup that offers diffraction-limited spatial control of Ag deposition on a glass surface (RA=reducing agent, for example citrate).
High concentrations of reactive nanoparticulate materials in water is the answer for many applications, such as in biolabelling and coatings, as the established synthetic procedures used to obtain bulk quantities of nanoparticulate materials are limited to organic media. The procedure reported provides metallic nanopa…
Just four electrons in each case dominate delocalised ring currents (see schematic diagram) in free-base porphin, chlorin and magnesium porphin, as has been revealed by direct visualisation of the π current density. The remaining 22 π electrons (20 in chlorin) are magnetically inactive in the presence of a field perpe…
The influence of Li doping on the crystallization behavior, morphology, and enhancement in photoemission intensity of Gd 2 - x Y x O 3:Eu 3+ solid−solution was investigated. To maximize an effect of the Li component which is volatile at elevated temperature, the citrate route was adopted for the synthesis at low tempe…
Photoinduced magnetization in a magnet based on organic species is reported for the first time. Upon optical excitation in the blue region of spectrum, Mn(tetracyanoethylene)(x)*y(CH2Cl2) (x approximately 2, y is approximately 0.8) exhibits increased magnetic susceptibility at temperatures as high as 75 K, accompanied…
We report on the observation of electron-hole ( $e\ensuremath{-}h$) liquid (EHL) in diamond by time-resolved luminescence measurements under an intense femtosecond photoexcitation above the band gap. The EHL luminescence band is observed below the $e\ensuremath{-}h$ plasma band, showing a finite rise time of several t…
This work describes the static and the dynamic properties of fractionated microcrystal cellulose “whiskers” using elastic and quasi-elastic light scattering techniques. These colloidal particles have been obtained by acid hydrolysis from raw materials (tunicate, a marine animal) that lead to stable aqueous suspensions…
Makroskopische Mengen einheitlicher Wolfram-Nanodrähte 3 mit Durchmessern von 20 bis 80 nm und Längen zwischen 5 und 30 μm entstehen bei einer einfachen Vakuumpyrolyse lamellarer Komposite aus WO42−-Ionen und Cetyltrimethylammonium(CTA+)-Tensidionen. Die lamellaren Komposite bildeten sich aus Aggregaten von CTA-WO4-Io…
Bulk quantities of uniform tungsten nanowires 3 with diameters of 20–80 nm and lengths ranging from 5 to 30 μm were obtained by a simple vacuum-controlled pyrolysis process from lamellar composites of WO42− ions and cetyltrimethylammonium (CTA+) surfactant ions. The lamellar composites were obtained from aggregates of…
In a one-pot reaction, the tetranuclear iron chelate complex [Fe4(L4)4] 6 was generated from benzene-1,3,5-tricarboxylic acid trichloride (4), bis-tert-butyl malonate (5a), methyllithium, and iron(II) dichloride under aerobic conditions. Alternatively, hexanuclear iron chelate complex [Fe(L5)6] 7 was formed starting f…
We investigate local electrostatics within a polyelectrolyte multilayer formed from layer-by-layer self-assembly of QPVP/PSS (quaternized poly(vinylpyridine)/poly(styrenesulfonate)), through the strategy of embedding, within this multilayer, a weak polyacid, PMA (poly(methacrylic acid)). The methods mainly involved in…
We have aligned the microdomains of a polystyrene- b -poly(2-hydroxyethyl methacrylate)- b -poly(methyl methacrylate) (PS- b -PHEMA- b -PMMA) triblock copolymer during preparation from solution by virtue of an external electric dc field (1.8 kV/mm). Bulk samples cast in the presence of an electric field exhibit lamell…
Nanonetze: Aus einer Suspension von einwandigen Kohlenstoff-Nanoröhren (single-walled carbon nanotubes; SWNTs) wurden elektrisch leitende Gitter mit 8 bis 14 Knotenpunkten (siehe Bild) erhalten. Die entscheidenden Strukturparameter dieser „Miniaturschaltkreise“ wurden hauptsächlich durch chemisch gesteuerte Selbstorga…
Electron holography performed in situ inside a high resolution transmission electron microscope has been used to determine the magnitude and spatial distribution of the electric field surrounding individual field-emitting carbon nanotubes. The electric field (and hence the associated field emission current) is concent…
Substantial levels of hydrogen, up to 6.5 wt %, have been stored in carbon nanofibers (CNFs) under conditions of 12 MPa pressure and ambient temperature. The magnitude of this result cannot be interpreted in terms of physisorption on the external surface alone. Kinetic studies indicate that a slow chemisorption proces…
A “minimal-lithography” technique for chemically assembling small deterministic crossbars of single-walled carbon nanotube (SWNT) ropes: The formation of electrically conducting crossbar circuits with 8 to 14 junctions (see picture) from a suspension of SWNTs is described. The critical structural parameters of the cir…
The presence of 10-13 M of chiral clusters of aromatic amino acids addresses aggregation of opposite-charged achiral porphyrin towards the formation of smart chiral assemblies. The latter supramolecular complexes are able to self-propagate and transfer their chiral information with a 100% yield. The chiral bias occurs…
An intramolecular ferromagnetic interaction (see picture) is evidenced for the first time in a dinuclear gadolinium complex that has four carboxylate bridges. A similar interaction exists in a dinuclear erbium complex, but, as a result of the depopulation of the excited Stark levels, its signature only appears at very…
Green chemistry principles have gradually been implemented into the development of the synthetic chemistry of high-quality semiconductor nanocrystals. In comparison with the original organometallic approach, the resulting alternative routes are safe, simple, inexpensive, reproducible, versatile, "user friendly", and y…
The results of structural refinements on high-resolution powder neutron diffraction data for copper(II)- and copper(I)-exchanged zeolite Y and for the parent sodium zeolite Y, with composition Na 62 Si 128 Al 64 O 384, are presented. Rietveld refinement of ambient-temperature data shows that the Cu(I) and Cu(II) catio…