Materials Literature
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The adsorption of pyrene-end-labeled poly(ethy1ene glycol) (Py-PEG-Py) onto aqueous colloidal polystyrene (PS) particles is investigated by photostationary fluorescence, fluorescence decay, and photostationary fluorescence depolarization experiments. All of the spectroscopic observations on this system suggest the ass…
The formation of the icosahedral quasicrystalline phase in the Al-Cr-Fe system has been investigated by X-ray diffraction as a function of the CrxFe1–x, composition of the transition-metal (TM) quasisublattice. An optimal range was found around x = 0·6, where the icosahedral phase shows the highest degree of structura…
This article introduces an unconventional electron optical probe forming system which is particularly suitable for low beam voltages and very large specimens, such as semiconductor wafers which also require a large angle tilting. The system can produce an electron probe of less than 20 Å for a nontilting specimen at 1…
Abstract Single crystals of β 1 and polycrystals of β 2 of POP and SOS were obtained from acetonitrile solution. The crystallization behavior of the two polymorphs was almost the same in POP and SOS; rapid cooling of the solution preferentially crystallized the metastable β 2 form, and the most stable β 1 form crystal…
A search for ferroelectric nematic liquid crystals is carried out on the basis of a simple theoretical model viewing the nonspherical polar molecules as hard ellipsoids of revolution with an embedded permanent dipole oriented along the symmetry axis. The density-dipole moment-aspect ratio phase diagram of the dipolar…
The anisotropic EPR signal already observed in x-ray-irradiated yttria-stabilized zirconia is analyzed between 140 and 300 K in samples containing 12% and 24% ${\mathrm{Y}}_{2}$${\mathrm{O}}_{3}$. A temperature-dependent broadening is detected and attributed to spin-lattice interactions whose mechanisms are discussed.…
We present a theoretical calculation of the Frank elastic constants of a nematic liquid crystal made of hard spherocylinders. We use the existing relations for these elastic constants together with the direct correlation function which we obtain consistently from a free-energy density-functional approximation recently…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTDepth dependence of alkali etching of poly(tetrafluoroethylene): effect of X-ray radiationR. R. Rye and G. W. ArnoldCite this: Langmuir 1989, 5, 6, 1331–1334Publication Date (Print):November 1, 1989Publication History Published online1 May 2002Published inissue 1 November 19…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTGround- and excited-state properties of a photostable hemicage ruthenium(II) polypyridine complexRuth Freitag Beeston, Steven L. Larson, and Michael C. FitzgeraldCite this: Inorg. Chem. 1989, 28, 23, 4187–4189Publication Date (Print):November 1, 1989Publication History Publi…
The development of the diamond-anvil cell has stimulated Raman-scattering investigation of vibrational modes in covalent crystals. The linear pressure coefficient reported for diamond by Hanfland et at' (2.90 ± 0.05 cm-1/GPa) agrees to within mutual experimental error with the result of Boppard et aL2 (2.87±0.01 cm-1/…
Li 2 O-V 2 O 5 -SiO 2 , thin films were fabricated by the rf sputtering method. The X-ray diffraction patterns of the film annealed at 500–600°C agreed with the γ-Li 3 VO 4 phase powder pattern. The as-sputtered film had an orientation of the (001) plane parallel to the substrate. The electrical conductivity of the an…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTA new class of room temperature luminescent organometallic complexes: luminescence and photophysical properties of permethylscandocene chloride in fluid solutionBrian W. Pfennig, Mark E. Thompson, and Andrew B. BocarslyCite this: J. Am. Chem. Soc. 1989, 111, 24, 8947–8948Pub…
Efficient syntheses of 2,4-dibromo- and 2,4-diiododeuteroporphyrin IX have been carried out by treating zinc(II) 2,4-bis(chloromercurio)deuteroporphyrin IX dimethyl ester (2) with bromine or iodine. Unavoidable meso-chlorination occurs when 2 is treated with chlorine and with other free-radical chlorinating agents. Re…
Some polymer radicals have been proposed as potential organic magnetic materials. In order to determine where to place the doublet or triplet centers on the side chains of a conjugated polymer chain, we have studied model dimers, i.e., isomeric bis(nitrenophenyl)acetylenes and diacetylenes. They were generated by phot…
Since polyimides were invented more than 30 years ago, several books dealing with the subject have been published [33, 34, 40u, 48b, 55, 64]. While some of these books [33–35] have very thorough and systematic coverage of the chemistry and general physical, mechanical, and electrical properties of polyimides, most of…
For light propagation in stratified media the normal component of the Poynting vector is defined as an indefinite scalar product. The vanishing of this scalar product for two waves is regarded as proof of their mutual orthogonality. Orthogonality in this sense is an inherent property of optical eigenmodes with differe…
We have established a simple icosahedral to face-centred icosahedral ordering transformation in Al–Mn quasicrystals. This result strongly supports the view that the recently discovered face-centred icosahedral quasicrystal in ternary Al–Cu–Fe and related alloys represents a long-range superstructure of simple icosahed…
Ce modele considere la fissuration comme un processus de Markov vectorise 2D. Deux lois de propagation des fissures de fatigue sont utilisees pour l'analyse, et une methode des integrales finies modifiee est proposee pour determiner les parametres du modele stochastique. Ce modele utilise les donnees de Virkler. Excel…
The annealing effect on the lattice distortion of porous silicon (PS) layers have been studied mainly by X-ray multiple-crystal diffractometry and infrared spectroscopy. The lattice spacing of PS layers changed with increasing annealing temperature and finally became smaller than that of the unanodized Si substrate ab…
The RHEED specular beam profiles produced by GaAs vicinal surfaces are examined and correlated with the surface topography. It is found that the shape of split peaks produced with the incident beam normal to step edges is a measure of surface orientation over lengths on the order of terrace widths, but is not sensitiv…