Materials Literature
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Chiralität auf der Streckbank: Chirale mesostrukturierte MCM-41-Siliciumoxid-Nanofasern (siehe TEM-Bild, die Pfeile zeigen sich wiederholende Einheiten an) mit einer oder zwei Drehachsen sind die Produkte einer einfachen Verdünnungssynthese ohne chirale Additive. Eine kontinuierliche Transformation von einer chiralen…
We investigate correlations between fluorescence photons emitted by single N-V centers in diamond with respect to the optical excitation power. The autocorrelation function shows clear photon antibunching at short times, proving the uniqueness of the emitting center. We also report on a photon bunching effect, which i…
Femtosecond transient absorption spectroscopy has been used to investigate the electron-electron scattering dynamics in sulfate-covered gold nanoparticles of 2.5 and 9.2 nm in diameter. We observe an unexpected retardation of the absolute internal thermalization time compared to bulk gold, which is attributed to a neg…
Abstract 4,4′‐Oxydiphthalic anhydride (1) was reacted with (s)‐(+)‐valine (2) in acetic acid and the resulting imide‐acid 3 was obtained in high yield. This compound 3 was converted to diacid chloride 4 by reaction with excess amount of thionyl chloride. The polycondensation reaction of diacid chloride 4 with several…
Monodisperse oligo(ethylene glycol)s were polycondensed with trimesoyl chloride using triethylamine as HCl acceptor. Despite nearly quantitative conversions and relatively high concentrations (0.4 mol/L), no gelation occurred with tri- and tetra(ethylene glycol), regardless of the feed ratio. With a feed ratio around…
Double-walled carbon nanotubes (DWCNTs) were synthesized by catalytic chemical vapor deposition using Fe-Mo/MgO as a catalyst at 1000 degrees C under the mixture of methane and hydrogen gas. The nanotubes were purified by acid but were not damaged. Thermogravimetric analysis revealed the purity of the tubes to be abou…
Bright blue-violet photoluminescence centered at 428nm was obtained in amorphous Si-in-SiNx thin films prepared in a cyclic growth mode on cool substrates by plasma-enhanced chemical vapor deposition, in which the typical size of the silicon particles has been brought down to ∼1.80nm and the number density amounts to…
Abstract Cd 1− x Zn x O thin films were prepared by spray pyrolysis in air atmosphere on a glass substrate at 250 °C. The Zn content in Cd 1− x Zn x O films was varied from x = 0 to 0.60. Structural, electrical and optical properties of Cd 1− x Zn x O films were investigated by x‐ray diffraction, electrical resistivit…
The molecular structure of various semi-fluorinated polymers derived from tetrafluoroethylene, hexafluoropropylene, and vinylidenefluoride is examined by different characterization methods in dilute solution. The polymer synthesis was tailored to set up samples with a straight linear topography as well as model polyme…
Abstract New 2 H ‐[1]benzothieno[3,2‐ b ]pyrroles were synthesized by a [1,5]‐sigmatropic shift of 3 H ‐benzothienopyrroles. The dependence of the rearrangement on solvent and temperature was studied. The first merocyanine dyes based on both 3 H ‐ and 2 H ‐benzothienopyrroles were synthesized and characterized by NMR‐…
Teflon® AF is truly a family of amorphous fluoropolymers with an extraordinary combination of properties. All of the excellent properties of the existing fluoropolymers have either been retained or improved upon and properties arising from the amorphous nature and the presence of microvoids in the AF family of polymer…
We report measurements on the radial electromechanical properties of single walled carbon nanotubes. By measuring the conductance of the nanotube, we show that a gap is opened while squashing the nanotubes and that during the deformation stages we observe at least two open-close cycles of the gap. We employ a novel ex…
[reaction: see text] Bridged phenylthienylethenes and dithienylethenes were synthesized via Pd-catalyzed double-cyclization reactions of (Z,Z)-1,6-diaryl-1,5-hexadien-3-ynes. Pd-catalyzed as well as photoinduced Z/E isomerization of the products were also investigated.
Three 3,4-bis(alkylthio)pyrroles ( 5a − c ) were synthesized by a nonclassical pyrrole ring formation reaction followed by alkylation of the dithiol-2-one functional group. UV−vis absorption studies together with time dependent density-functional theory (TD-DFT) computations suggest that the monomers ( 5a − c ) displa…
The dynamics of cis-1,4-polybutadiene (cis-1,4-PB) over a wide range of temperature and pressure conditions is explored by conducting atomistic molecular dynamics (MD) simulations with a united atom model on a 32-chain C128 cis-1,4-PB system. The local or segmental dynamics is analyzed in terms of the dipole moment ti…
Abstract Chitin and chitosan with improved characteristics were produced from shrimp shell waste preconditioned by limited decay or by treatment with 0.016 mol L −1 benzoic acid. Preconditioned shrimp shells were transparent, had a clean surface and were susceptible to demineralization and deproteinization using 0.68…
All of the unique properties imparted by fluorocarbons can be traced back to a single origin: the nature of the C—F bond. These properties include low surface tension, excellent thermal and chemical stability, low coefficient of friction, and low dielectric constant. However, not all of these properties are possessed…
The preparation and characterization of the five-coordinate iron(II) porphyrinate derivative [Fe(TpivPP)(NO3)]- (TpivPP = picket-fence porphyrin) is described. Structural and magnetic susceptibility data support a high-spin state (S = 2) assignment for this species. The anionic axial nitrate ligand is O-bound, through…
Abstract After being subjected to preliminary purification, montmorillonite clay was leached with varying concentrations of sulfuric acid (0.5–2 mol L −1 ) at 90 °C for varying times (0.5–4 h). Acid leaching causes partial amorphization of the montmorillonite and increases its specific surface area by a factor of 3 (f…
The controlled generation of single photons is mandatory for applications in quantum communication, in particular for secure quantum cryptography, and also for a number of fundamental problems in quantum optics. Here, we present a stable all solid-state source for single photons utilizing the fluorescence light from a…