Materials Literature
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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…
The growth and structure of Fe and Co thin films on single-crystal Cu(111), Cu(100), and Cu(110) substrates have been investigated using x-ray-photoelectron and Auger electron forward scattering, CO-titration, low-energy electron diffraction, and reflection high-energy electron diffraction. The motivation for this stu…
Photoluminescence and Raman spectroscopy are employed to explore the time evolution of defect formation in chemical vapor deposition diamond films for stages of growth spanning nucleation to continuous film formation. Our research is concentrated on three types of defects which give rise to the 1.68 eV optical band, t…
Results of an annealing study, carried out in the temperature range 1500–1900 °C, of nickel-related optical centers in high-pressure synthetic diamond are presented. It is established that the well-known 1.883 and 2.51 eV systems anneal out during the temperature regime of nitrogen aggregation and the concurrent growt…
Recent refinement studies of a consolidated set of Si structure factors have produced information on the Si charge density with an unprecedented level of accuracy, unmatched by any other crystallographic study to date. In this work we examine the extent to which an accurate implementation of the local-density formalis…
The effect of nonspherical shape on the optical properties of semiconductor microcrystals with a degenerate valence band has been theoretically studied. The asymmetry of microcrystals leads to a splitting of the fourfold-degenerate ground hole state into two twofold-degenerate ones. The value of this splitting is prop…
The current two major non-numerical design methods, equivalent layers and polynomial synthesis, are reviewed and compared. The equivalent layer method works well when only a small number of fixed refractive indices is available. This is the case when the coating is manufactured by evaporation. Polynomial synthesis gen…