Materials Literature
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Epitaxial thin films of naphthalocyanines (Nc’s) were prepared on the (001) surface of alkali halide (AX) by a vacuum-deposition technique. Two types of molecular stacking and orientation were found depending on the molecular structure. Metal-free Nc(H2Nc) and divalent zinc Nc(ZnNc) took the face-to-face, eclipsed sta…
The structural and electronic properties of iron clusters ${\mathrm{Fe}}_{\mathit{n}}$ (n\ensuremath{\le}5) are studied using a Gaussian orbital local (nonlocal) spin-density method. Starting from n=2 and 3 with localized multiple d bonds and short equilibrium bond lengths, ${\mathit{R}}_{\mathit{e}}$\ensuremath{\sime…
The defects in ${\mathit{p}}^{+}$ porous silicon of low and high porosity have been studied by using electron-paramagnetic-resonance (EPR) spectroscopy and compared with an impurity analysis obtained from nuclear reaction analysis (NRA). The EPR measurements show, in both high- and low-porosity samples, the same domin…
We present the results of time-resolved luminescence studies of poly[2-methoxy, 5-(2′-ethyl-hexyloxy)-p-phenylene-vinylene] (MEH-PPV), as a pure film, in solution, in a gel formed by a network of ultrahigh molecular weight polyethylene (UHMW-PE), and in a blend with UHMW-PE. The luminescence has a characteristic lifet…
Abstract It has been discovered that a combination of heat and high‐power ultrasound can be used to initiate ring‐opening polymerization in cyclic bisphenol A polycarbonate oligomers. The polymerization can be conducted with or without the use of added chemical initiators. The use of ultrasound was extended to prepare…
Abstract Blends of propylene–ethylene block copolymer (PEB) and propylene homopolymer (PP) were prepared to give various rubber contents (4–20 wt %). By diluting the PEB with PP with molecular weight equal to that of the PEB matrix, molecular characteristics of all the blends were kept constant. The rubber particle si…
The spectra of optical constants of α-Al 2 O 3 single crystals at 297 K and 10 K are presented over the range of photon energies from 6 eV to 120 eV for the electric fields of incident light parallel to optic axis < c > and normal to it. The optical constants include the complex index of refraction, conductivity, comp…
Tatsumisago, Angell, and Martin [J. Chem. Phys. 97, 6968 (1992)] have compared conductivity relaxation data and 7Li nuclear spin lattice relaxation (SLR) data measured on a lithium chloroborate glass and found pronounced differences in the most probable relaxation times. The electrical conductivity relaxation (ECR) ti…
The bead-spring model pioneered by Rouse is generally considered to be the basis of polymer physics. We show generally that it breaks down dramatically near the glass transition temperature by shear creep measurements on several polymers with very different backbone structures. The physical origin of this breakdown is…
A model for a multichain polymer system in three-dimensional continuous space is studied by link cell Monte Carlo methods, using systems up to chain length N=64 and up to 16 384 monomers. The chains consist of beads with a hard core connected by rather stiff harmonic bonds, with a repulsive Lennard-Jones-type interact…
Experiments with local gas feeds of methane or acetylene indicate that both ${\mathrm{C}}_{2}$${\mathrm{H}}_{2}$ and ${\mathrm{CH}}_{3}$ contribute to the growth of (111) surfaces, whereas only ${\mathrm{CH}}_{3}$ contributes to that of the (100) surface. High-resolution electron-energy-loss spectroscopy has been used…
We outline a method for the calculation of nonlinear properties such as dynamic hyperpolarizabilities for self-consistent-field (SCF) wave functions. In this method, two-electron integrals are only addressed in the evaluation of Fock matrices and Fock matrices with one-index transformed integrals. These matrices are d…
The reflectivity spectrum of Y 3 Al 5 O 12 (YAG) single crystals at 297 K is presented in the region of 6.734 eV ≤ E ≤116 eV. The spectra of optical constants derived from the reflectivity by the Kramers-Kronig analysis are tentatively interpreted in terms of the energy levels of the constituent atoms of YAG. Plasma r…
Abstract We consider the geometries of hypothetical structures, derived from a graphite net by the inclusion of rings of seven or eight bonds, which may be periodic in three dimensions. Just as the positive curvature of fullerene sheets is produced by the presence of pentagons, so negative curvature appears with a mea…
When clean, vacuum-fractured surfaces of ${\mathrm{BaTiO}}_{3}$ are analyzed using ultraviolet and x-ray photoelectron spectroscopy (UPS and XPS), more than one set of barium core levels is observed. Sputtering the surface with ions removes lower-binding-energy intensity within the barium line shapes in UPS spectra wh…
Neutron diffraction and magnetization measurements have been made on single crystal specimens of hexagonal-ferrite helimagnet (Ba 1- x Sr x ) 2 Zn 2 Fe 12 O 22 ( x =0.748) in a field applied perpendicular to the c -axis. Two types of intermediate phases, intermediate-I and -II, are successively induced by a field, and…
Ion implantation of H2+ or O+ ions in the range 0–1.7×1015 and 0–1.3×1015/cm2, respectively, was used to investigate the effect of implant-induced damage on the electrical properties of Sn-doped In2O3 (ITO) films deposited by electron-beam evaporation on SiO2-coated soda-lime glass substrates. The films were character…
Pulsed-laser ablated uranium atoms were codeposited with 14N2(15N2) and excess Ar at 12 K. The Fourier transform infrared (FTIR) spectrum revealed a single product, UN2, which exhibited a ν3 absorption at 1051.0 cm−1. Ultraviolet (UV) photolysis increased the yield of UN2 by threefold and showed that electronic excita…
Raman scattering of thin laser-deposited amorphous-carbon films reveals significant changes in lower and intermediate spectral regions with respect to rf-sputtered, predominantly threefold a-C. The form of the spectrum differs, however, from the expected spectrum for fourfold, diamondlike a-C. It is suggested that mix…
We report in situ x-ray photoemission, ultraviolet photoemission (UPS), and electron-energy-loss photoelectron-spectroscopy studies of the electronic structure of nitrogen-containing amorphous hydrogenated carbon (a-${\mathrm{CN}}_{\mathit{x}}$:H). Films with different nitrogen concentrations are prepared by the ion-b…