Materials Literature
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ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTHeats of formation of silicon hydride oxide (SiHnO and SiHnO2) calculated by ab initio molecular orbital methods at the G-2 level of theoryCynthia L. Darling and H. Bernhard SchlegelCite this: J. Phys. Chem. 1993, 97, 31, 8207–8211Publication Date (Print):August 1, 1993Publi…
A large fraction of the chemical and refinery processes are catalytic in nature. While the worldwide sales of catalysts are only about $4 billion annually, the economic impact of catalysis comes from the fact that approximately $200 worth of products are manufactured for every $1 worth of catalyst consumed [1]. The ac…
The most important factors contributing to line broadening and background intensity in electron spectra are identified and new design principles for high quality measurements are presented. It is shown that time-dependent potential gradients in the gas cell are responsible for a large part of the ‘‘normal’’ line broad…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTEffect of the spacer moiety on the rates of electron transfer within bis-porphyrin-stoppered rotaxanesJean Claude Chambron, Anthony Harriman, Valerie Heitz, and Jean Pierre SauvageCite this: J. Am. Chem. Soc. 1993, 115, 16, 7419–7425Publication Date (Print):August 1, 1993Pub…
New experimental results of low-frequency Raman scattering from different glasses are presented. They are compared to the vibration density of states obtained from inelastic neutron scattering to deduce the light-vibration coupling coefficient C(ω) as a function of the vibration frequency. It was found that C(ω)∝ω2 at…
We report measurements of the specific heat ${\mathit{C}}_{\mathit{p}}$(T), magnetic susceptibility \ensuremath{\chi}(T), and magnetization M(H) of icosahedral ${\mathrm{Al}}_{70}$${\mathrm{Mn}}_{9}$${\mathrm{Pd}}_{21}$ at low temperatures. Below room temperature, the static magnetic susceptibility is well described b…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSynthesis and properties of novel aromatic polyimides of 2,3-bis(4-aminophenoxy)naphthaleneChin Ping Yang and Wen Tung ChenCite this: Macromolecules 1993, 26, 18, 4865–4871Publication Date (Print):August 1, 1993Publication History Published online1 May 2002Published inissue…
The atomic displacements of many of the atoms in a macromolecular structure can be modelled in terms of group motions described in the harmonic approximation by T, L and S tensors. Relevant groups may be planar side groups of protein chains, units of secondary structure such as α-helices or whole protein domains. For…
Abstract Four new epoxy monomers have been synthesized and characterized as part of a program to prepare novel liquid crystal thermoset (LCT) materials. Three of the new epoxy monomers contained a biphenyl mesogen and were not liquid crystalline (LC). The remaining epoxy monomer, which contained a 1,4‐dibenzoyloxybenz…
Samples of liquid crystalline poly(γ-benzyl-glutamate) solutions are sheared between glass surfaces with gaps, d = 10–500 μ, and shearing velocities, V = 0·05–10 000 μs−1 so that the Ericksen number E [tbnd] Vdγ 1/K is varied over a large range, E ≈ 1–107. Here γ1 is the rotational viscosity and K 1 is the Frank splay…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTEnd-functionalized polymers. 1. Synthesis and characterization of perfluoroalkyl-terminated polymers via chlorosilane derivativesM. O. Hunt Jr., A. M. Belu, R. W. Linton, and J. M. DeSimoneCite this: Macromolecules 1993, 26, 18, 4854–4859Publication Date (Print):August 1, 19…
ADVERTISEMENT RETURN TO ISSUEArticleNEXTFormation of hydronium at the Broensted site in SAPO-34 catalystsLeonardo Marchese, Jiesheng Chen, Paul A. Wright, and John Meurig ThomasCite this: J. Phys. Chem. 1993, 97, 31, 8109–8112Publication Date (Print):August 1, 1993Publication History Published online1 May 2002Publishe…
The dilute-limit heats of solution for all binary alloys of six bcc transition metals (V, Nb, Ta, Mo, W, and Fe) have been calculated with the analytic embedded-atom model for bcc pure metals by Johnson and Oh. Cubic equations are proposed and used for providing a smooth cutoff for the calculated potential and electro…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTNew antiferromagnetic dinuclear complexes of nickel(II) with two azides as bridging ligands. Magneto-structural correlationsJoan Ribas, Montserrat Monfort, Carmen Diaz, Carles Bastos, and Xavier SolansCite this: Inorg. Chem. 1993, 32, 16, 3557–3561Publication Date (Print):Au…
To investigate the effects of oxygen codoping on Er luminescence centers in GaAs, we grew Er-doped GaAs by low-pressure metalorganic chemical vapor deposition (MOCVD) and measured the photoluminescence spectrum due to the intra-4f-shell transition of Er. The spectrum of a sample grown in a pure hydrogen atmosphere was…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTTwo new .mu.-azido nickel(II) uniform chains: syntheses, structures, and magneto-structural correlationsAlbert Escuer, Ramon Vicente, Joan Ribas, M. Salah El Fallah, Xavier Solans, and M. Font-BardiaCite this: Inorg. Chem. 1993, 32, 17, 3727–3732Publication Date (Print):Augu…
Transition-state theory was employed to study the dynamics of light gases dissolved in rigid microstructures of glassy polycarbonate and rubbery polyisobutylene modeled in atomistic detail. The gaseous molecules migrated through the polymer structures in a sequence of ‘‘hops’’ between local minima of the potential ene…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTInvestigation of intermediate steps in the self-assembly of n-alkanethiols on gold surfaces by soft x-ray spectroscopyG. Haehner, C. Woell, M. Buck, and M. GrunzeCite this: Langmuir 1993, 9, 8, 1955–1958Publication Date (Print):August 1, 1993Publication History Published onl…
The quasiperiodic structure of decagonal Al 70 Ni 15 Co 15 was determined on the basis of X-ray single-crystal intensity data using the n-dimensional embeding method. Centrosymmetric five-dimensional space group P10 5 /mmc, three-dimensional reciprocal and direct quasilattice parameters: a i * =0.2636 (1) A -1 , i=1,.…
First- and third-order dynamic polarizabilities and hyperpolarizabilities of aza-cyanine and symmetric cyanine dyes have been computed exactly within the correlated Pariser–Parr–Pople model defined over the π framework. The exact nonlinearities of the model have been compared with those of polyenic systems. It is foun…