Materials Literature
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Diamond films were grown by microwave plasma chemical vapor deposition on as-received platinum (Pt) foils, specially processed Pt foils with (111) domains, bulk single-crystal Pt with a (111) surface, and single-crystal Pt(111) films deposited on strontium titanate (111). In all cases, the substrate surfaces had been…
The microporous structure of artificial vascular grafts, which increases compliance and porosity simultaneously, may enhance neoarterial regeneration. In order to differentiate these effects, three models of segmented polyurethane grafts (inner diameter, 1.5 mm; wall thickness, 100 microns) with or without micropores…
Optical absorption and emission properties of Er3+ ions in ZnCl2-based glasses are investigated. The electric dipole line strengths for various transitions were estimated from the measured optical absorption spectra. The spontaneous emission probabilities for various transitions were predicted using the Judd–Ofelt the…
Nanosize neutral silicon clusters produced using a laser vaporization source were analyzed in the gas phase and deposited on various substrates at room temperature in ultrahigh vacuum. Nanostructured thin films with thickness around 100 nm resulting from this nearly ballistic deposition process were subsequently chara…
Behavior as single-molecule gates for certain ions is demonstrated by dendrimers confined on surfaces and within thiol monolayers (see picture). The permeability depends on the chemical state of the dendrimer and the charge on the ion. These composite structures are models of biological membranes in that mass transfer…
A systematic study of the desorption behavior of Sb multilayers applied as a passivant to (001) GaAs is presented. Reflection high-energy electron diffraction, reflectivity, Auger electron spectroscopy, x-ray photoelectron spectroscopy, and thermal desorption data reveal unique and complementary information which can…
Plasma-enhanced chemical vapor deposition has been used for the deposition of diamond and diamond-like thin films during the last decade with great success. Here we present experimental evidence that a chemical vapor deposition technique can also be used to synthesize other forms of carbon including fullerenes and hyd…
Redox transmetallation ofTl(C5H4PPh2)with an excess of Sm in refluxing thf (thf = tetrahydrofuran) or Eu indme (dme = 1,2-dimethoxyethane) at room temperature gave thelanthanoid(II) compounds[Sm(C5H4PPh2)2](1) and[Eu(C5H4PPh2)2(dme)](2). Crystallization of (1) or[Yb(C5H4PPh2)2(dme)]with OPPh3 in dme yielded[Sm(C5H4PPh…
Room temperature absorption and reflectivity data are presented for Cd2P2S6 and Cd2P2Se6 crystals in the range of photon energies between 1.6 and 5.5 eV. For both compounds the characteristic feature of the optical absorption is that their absorption edge appears to correspond to an indirect allowed transition with an…
A simple model is presented to estimate the low-energy electron mean free path in transition metals and to calculate its spin dependence. In this model, the electron-scattering rate is directly related to the number of holes in the $d$ bands; its spin asymmetry is almost proportional to the spin magnetic moment. These…
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The theory of spin-restricted Brueckner orbitals for high-spin open-shell coupled-cluster wavefunctions is presented. The orbitals are based on single-excitation amplitudes constructed using the symmetric spin–orbital basis coupled-cluster method of Jayatilaka and Lee. It is shown how this approach may be easily imple…
The most stable of the three possible structural isomers of corrole is, according to theory, isocorrole, for which the title compound 1 is a model compound. The reductive McMurry coupling of the corresponding α,ω-tetrapyrroledialdehyde affords an entry to 1. The isocorrole derivative 1 has, like corrole, the propensit…
We report that the sign of the polarization of an epitaxial ferroelectric film can be determined from the interference between the x-ray scattering from the film and the substrate. X-ray scattering measurements of a 10 nm epitaxial PbTiO3 film grown by metal-organic chemical vapor deposition on a SrTiO3 substrate are…
Durch eine optimale Abstimmung der Donor‐Acceptor‐Stärken in heterocyclischen Methinfarbstoffen wie 1 kann der Cyaninzustand erreicht werden. Trotz nahezu verschwindender Polarisierbarkeiten zweiter Ordnung (β) setzt diese Chromophorklasse neue Maßstäbe für photorefraktive Anwendungen. Bereits bei einem Chromophorgeha…
It is argued that the model advanced by Lenef and Rand [Phys. Rev. B 53, 13 441 (1996)] for the nitrogen-vacancy center in diamond, exhibiting the 1.945-eV luminescence is incorrect. Lenef and Rand argue that the electronic ground state consists of two electrons occupying ${a}_{1}$ states localized on N and C, respect…
Für die Entwicklung von molekularen Schaltern sind Cobalt‐ und Mangankomplexe mit 1,2‐Benzochinon‐Liganden von großem Interesse. Diese Verbindungen haben elektronisch instabile Grundzustände, was zu Phänomenen wie gemischte Valenz, Spincrossover und Valenztautomerie führt. In jüngster Zeit wurde das elektronische Verh…
Absorption, emission, and excitation spectra of KMgF${}_{3}$ doped with Ce${}^{3+}$ have been measured in the near ultraviolet up to 180 nm. In this fluoroperovskite lattice, absorption of the Ce${}^{3+}$ impurity is found at energies higher than 4.4 eV. Broad-band emissions are measured at 350 nm and 275 nm which are…
Hydrothermally prepared zinc dihydroxy divanadate dihydrate crystallizes in the trigonal system (space group P\overline{3}m1). Its structure was solved ab initio from conventional X-ray powder data. Zn atoms occupy three of four octahedral sites in the close-packed layer of O atoms. These layers are connected by pyrov…
Abstract A large number of TADDOL (α,α,α′, α′‐ t etraaryl‐1,3‐ d ioxolan‐4,5‐ d imethan ol ) derivatives has been tested as chiral dopants for inducing conversion of nematic to cholesteric phases. With the Merck liquid‐crystal materials ZLI‐1695 and K15 , it was demonstrated that some TADDOLs have unprecedentedly high…