Materials Literature
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Quinoidalization results in amazingly intense near-IR absorption in 1 (λmax=1080 nm), whereas the shorter dimer 2 (λmax=780 nm) is less conjugated because steric interactions force it into a contorted geometry. The crystal structure of 1 shows that the 62-atom chromophore is bow-shaped in the solid state.
Dielectric susceptibility, X-ray diffraction and infrared molecular vibrational spectra have been investigated for a charge-transfer complex, tetrathiafulvalene (TTF)-2-bromo-3,5,6-trichloro- p -benzoquinone (QBrCl 3 ) to probe a ferroelectric valence transition at T c =66 K in comparison with the typical first-order…
Epitaxial SrBi2Nb2O9 thin films have been grown with a (103) orientation on (111) SrTiO3 substrates by pulsed-laser deposition. Four-circle x-ray diffraction and transmission electron microscopy reveal nearly phase-pure epitaxial films. Epitaxial (111) SrRuO3 electrodes enabled the electrical properties of these (103)…
Novel elastomeric A-B-A triblock copolymers were successfully synthesized in a new two-step process: controlled ring-opening polymerization of the cyclic ether–ester 1,5-dioxepan-2-one as the amorphous middle block (B-block) followed by addition and polymerization of the two semicrystalline L-lactide blocks (A-block).…
Herein, we describe the design, synthesis, structure, and function of synthetic, supramolecular beta-barrel models. Assembly of octi(p-phenylene)s with complementary -Lys-Leu-Lys-NH2 and Glu-Leu-Glu-NH2 side chains yielded water-soluble rigid-rod beta-barrels of precise length and with flexible diameter. A hydrophobic…
Nineteen commercial high-density polyethylene resins made with different polymerization processes and catalyst types were analyzed by high-temperature size exclusion chromatography and crystallization analysis fractionation. The information obtained with these characterization techniques on the polymer chain structure…
Polarization dependence of soft-x-ray Raman scattering was investigated at the Ti $2p$ absorption edge of ${\mathrm{TiO}}_{2}.$ Strong Raman scattering feature appears about 14 eV below elastic peaks with strong polarization dependence. These Raman scattering structures are charge transfer excitations to the antibondi…
The structural and magnetic characteristics of the recently discovered quantum spin ladders are summarised and the possibilities of supramolecular chemistry for developing such fascinating materials are discussed. The existing examples of molecular spin ladders clearly show that typical supramolecular and crystal engi…
Helium has a decisive effect on the microstructure of silicon carbide materials after implantation and subsequent annealing. A dense population of bubbles and dislocation loops is already observed at relatively low displacement doses after annealing of helium-implanted \ensuremath{\alpha}-SiC, while no visible damage…
Zero-field 57 Fe NMR spectrum has been observed in the 57 Fe-enriched ceramics of BiFeO 3 . The analysis of NMR lineshape confirms the existence in this ferroelectric-antiferromagnetic compound of a long-period cycloidal magnetic structure and enables the first reconstruction of the actual spatial spin distribution al…
We report the dielectric anomaries at the phase transitions of Lu(Fe 2+ Fe 3+ )O 4 , which is considered as a charge and spin frustrated system. Dielectric constant shows a hump, just above the transition from the high temperature two-dimensional to the low temperature three-dimensional charge ordering. A few glassy b…
The surface-enhanced resonant Raman-scattering (SERRS) spectra of single-walled carbon nanotubes (SWNT's) adsorbed on silver and gold metal island films and on colloidal silver cluster substrates were investigated using different laser excitation wavelengths. The observed enhancement in the SERRS signal of the SWNT's…
We have studied electric-field-induced Raman scattering in SrTiO3 thin films using an indium-tin-oxide/SrTiO3/SrRuO3 structure grown by pulsed laser deposition. The soft mode polarized along the field becomes Raman active. Experimental data for electric-field-induced hardening of the soft modes and the tuning of the s…
We present an extensive electron energy loss spectroscopy study of the low-loss energy region, recorded on multishell carbon and boron-nitride nanotubes and carbon hyperfullerenes. Collections of spectra were recorded in a scanning transmission electron microscope by scanning a subnanometer probe from vacuum into the…
The hexa-tert-butyl substituted hexa-peri-hexabenzocoronene was synthesized in an overall yield of 83% from 4-tert-butylphenylacetylene. The key step was the oxidative cyclodehydrogenation of hexa(4-tert-butylphenyl)benzene with anhydrous FeCl3 in CH2Cl2 The high solubility of hexa-tert-butyl-hexa-peri-hexabenzocorone…
A series of BaTiO3 thin films with various thicknesses from 10 to 400 nm were epitaxially grown under various oxygen pressures from 2×10−4 to 12 Pa on SrTiO3 (001) substrates using laser molecular beam epitaxy. Being confirmed by reflection high energy electron diffraction, atomic force microscopy, x-ray diffraction,…
We investigated the hydrostatic and shear strain components introduced in the graphite hexagons by applying hydrostatic pressure to single-walled carbon nanotubes. The vibrational modes are expected to show different pressure derivatives depending on the polarization of the eigenvector with respect to the nanotube axi…
The structure and electronic properties of 1-ML Au supported on ${\mathrm{TiO}}_{2}(110)$ have been theoretically investigated using the full potential linearized augmented plane-wave method. Based on total-energy and atomic-force calculations, the preferential adsorption site for the Au adatom is predicted to be the…
Specific peaks of the Raman spectrum of single-wall nanotubes shift significantly upon immersion of the tubes in a liquid, relative to the corresponding peaks in air. This observation means that nanotubes are sensitive to molecular forces, and is interpreted by relating the corresponding molecular strain to a thermody…
Extended π-conjugated systems and tunable optic properties are characteristic for compounds with linear backbones based on electron-donating thiophene, electron-accepting pyridine, and a σ3,λ3-phosphole core. The oligomers 1 and 2 are fluorescent chromophores and, for 2, these properties are tunable through chemical m…