Materials Literature
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A spectroscopic investigation of jet-cooled diatomic NiC has revealed a complex pattern of vibronic levels in the wave number range from 21 700 to 27 000 cm−1. Of the more than 50 vibronic bands observed, 31 have been rotationally resolved and analyzed. All are Ω′=0+←Ω″=0+ transitions, consistent with the calculated Σ…
A correct and verifiable model of the dielectric loss factor of BaxSr1−xTiO3 as a function of temperature, biasing field, barium concentration, and frequency has been developed in frequency range 0.1–100 GHz. Contributions to the loss factor of fundamental, quasi-Debye, acoustic, and low frequency relaxation mechanism…
Raman-scattering spectra of the type II clathrates Cs8Na16Si136, Cs8Na16Ge136, and Si136 were studied employing different laser wavelengths. Most of the Raman-active vibrational modes of these compounds were identified. Polarization measurements were used to identify the symmetric modes. The lowest frequency Raman-act…
Analysis of the dielectric relaxation phenomena in Bi2O3–ZnO–Nb2O5 cubic pyrochlore utilizing the Arrhenius equation is revisited to include recent high-frequency measurements. The fitting parameters obtained are further analyzed by comparison with theoretical and experimental activation energies of better understood…
A series of five cyclic block copolymers of styrene and butadiene, having essentially the same molecular weight (52 ± 5 kg/mol) and PS volume fraction varying from 11 to 70%, were synthesized by cyclization of α,ω-dilithium polystyrene−polybutadiene−polystyrene triblock copolymers with bis(dimethylchlorosilyl)ethane.…
We have conducted a density functional theory investigation into the gas-phase reactivity of small gold cluster ions in the interest of understanding gold cluster reactivity in several catalytic systems. Previously unreported geometries for Au9− and Au10− anions are obtained and reported from geometry optimizations. P…
Chalcogenide glasses belong to an important class of materials, due to their good infrared transmission, and low-phonon energy as compared to other oxide glasses. Structural and chemical variations imposed by glass processing conditions, e.g., film deposition, can lead to changes in the linear and nonlinear optical pr…
We have measured the cathodoluminescence (CL) spectra of silicon dioxide (SiO2) films prepared by a variety of methods and observed peaks at 280, 445, 480, 520, and 640 nm. A comparison of the CL and electron spin resonance spectra of Si-doped quartz glass showed that the 445 and 480 nm peaks originated from oxygen va…
A variation of Raman feature on excitation wavelength in silicon nanowires was observed. Based on the quantum size confinement effect, the resonant Raman scattering phenomenon and the existence of different sizes of Si grains in the samples, a plausible mechanism to interpret the novel feature was proposed and support…
Abstract The isothermal crystallization kinetics of blends of different polypropylene (PP) resins and a liquid crystalline polymer (LCP) after two different melting conditions (200 and 290°C) were studied by DSC and polarized light optical microscopy. The resins were a homopolymer (hPP), a random copolymer with ethyle…
Perdeuterated 4’-pentyl-4-cyanobiphenyl (D5CB) was synthesized and its physical properties evaluated and compared to those of 5CB. D5CB retains physical properties similar to those of 5CB, such as phase transition temperatures, dielectric constants, and refractive indices. An outstanding feature of D5CB is that it exh…
Because hyperbranched poly(amidoamine) dendrimers are relatively well-defined polycations with a high density of charge, they provide unique materials for controlled synthesis of films by alternating electrostatic adsorption of polycations and polyanions. Thicknesses of generation 4 (G4) dendrimer/poly(acrylic acid) (…
Macroporous silicon with two-dimensional periodicity has been produced by electrochemical etching, using a p-type doped silicon substrate. The structure shows photonic energy gaps in the infrared region, as demonstrated by variable angle reflectance measurements. The agreement between measurement and band calculations…
We have performed a detailed study of the polarization properties and switching behavior of holographic polymer-dispersed liquid-crystal gratings. A theoretical model [ R. L. Sutherland , J. Opt. Soc. Am. B19, 2995 (2002)] is compared with a number of observed phenomena in reflection and transmission gratings made wit…
The light scattering properties of boron doped diamond film have been investigated by Raman spectroscopy using ultraviolet (325 and 244 nm) and visible (514 nm) excitations. The relative intensity of electronic Raman scattering to phonon scattering decreases with the increase of the excitation energies, while the Fano…
An optical study of the redox of Ag nanoparticles was carried out by loading the particles into the pores of monolithic mesoporous silica. The optical absorption of silver nanoparticles was measured after annealing in different atmospheres. It has been found that treatment in H2 or N2 induces a strong surface plasmon…
The first cocrystal structure of a bacterial FabH condensing enzyme and a small molecule inhibitor is reported. The inhibitor was obtained by rational modification of a high throughput screening lead with the aid of a S. pneumoniae FabH homology model. This homology model was used to design analogues that would have b…
Two heterodimetallic complexes of formulae [LCo(MeOH)Gd (NO3)3] (1) and [LCo(AcO)2Gd(NO3)2] (2) (H2L = 1,3-bis[(3-methoxysalicylidene)amino]-2,2'-dimethylpropane) have been synthesized and characterized. The structure of 1 consists of discrete dinuclear entities. The cobalt(II) ion exhibits a square-pyramidal geometry…
In a recent paper [J. Am. Chem. Soc. 123, 7951 (2001)] we have shown for the first time the existence of molecules with nontotally symmetric vibrational modes that break the maximum hardness (MHP) and minimum polarizability (MPP) principles. We present here an extension of this previous work by devising a mathematical…
Antimony in two oxidation states: The mixed-valent thioantimonate anion [Sb4S9]4− in the compound [Ni(dien)2]2Sb4S9 contains SbVS4 tetrahedra, which are bound by one terminal S atom to the Sb3S7 backbone of the anion (see figure). dien=diethylenetriamine.