Materials Literature
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We report on a study of phonons in diamond using a new instrument for high resolution inelastic x-ray scattering at the Advanced Photon Source. We have paid particular attention to possible overbending of the most energetic branches, i.e., LO along both $\ensuremath{\Gamma}\ensuremath{-}X$ ( $\ensuremath{\equiv}\ensur…
Asymmetric polarization switching of Pb(Zr,Ti)O3 (PZT) thin films with different electrode configuration has been studied in (La,Sr)CoO3/Pb(Zr,Ti)O3/(La,Sr)CoO3 (LSCO) heterostructures in which the conducting oxide (La,Sr)CoO3 and/or LaCoO3 (LCO) have been used as an electrode. Polarization-voltage (P-V) hysteresis lo…
Compact expressions, complete through second order in electrical and/or mechanical anharmonicity, are given for the dynamic dipole vibrational polarizability and dynamic first and second vibrational hyperpolarizabilities. Certain contributions not previously formulated are now included.
Zero-order metal diffraction gratings may give remarkably strong absorption of radiation. This absorption is due to the excitation of standing wave coupled surface plasmons in the narrow grating grooves. Theoretical modeling shows that a family of resonances exists, as the grating grooves are deepened, corresponding t…
Fluorinated amorphous carbon (a-CFx) films were studied by high-resolution x-ray absorption, emission, and photoelectron spectroscopy. The composition and local bonding information were obtained and correlated with substrate temperature during deposition. The data suggest that the structure of the a-CFx is mostly of c…
Spectroscopic ellipsometry (SE) has been used to determine the complex pseudo dielectric functions, ε1(E)+iε2(E), of ZnO films on (0001) Al2O3 substrates over the spectral range of 1.33 and 4.96 eV at room temperature. The SE measurements are carried out with E⊥c at angles of incidence of 60° and 65° with respect to t…
We study hysteresis for a two-dimensional, spin-1/2, nearest-neighbor, kinetic Ising ferromagnet in an oscillating field, using Monte Carlo simulations. The period-averaged magnetization is the order parameter for a proposed dynamic phase transition (DPT). To quantify the nature of this transition, we present the firs…
We report intercalation of charged polyiodide chains into the interstitial channels in a single-wall carbon nanotube (SWNT) rope lattice, suggesting a new carbon chemistry for nanotubes, distinctly different from that of graphite and ${\mathrm{C}}_{60}$. This structural model is supported by results from Raman spectro…
Rope-like bundles of single-walled carbon nanotubes (SWNTs) similar to those obtained by laser vaporization and electric-arc techniques were synthesized on a relatively large scale and at low cost by the catalytic decomposition of hydrocarbons at a temperature of about 1200 °C using an improved floating catalyst metho…
Room-temperature ultraviolet (UV) laser emission of ZnO microcrystallite thin films is reported. The hexagonal ZnO microcrystallites are grown by laser molecular beam epitaxy. They are self-assembled and parallelly arrayed on sapphire substrates. The facets of the hexagons form natural Fabry–Pérot lasing cavities. The…
Starting from Enskog equation of hard spheres of mass m and diameter D under the gravity g, we first derive the exact equation of motion for the equilibrium density profile at a temperature T and examine its solutions via the gradient expansion. The solutions exist only when βμ\le μ_o \approx 21.756 in 2 dimensions an…
The temperature dependence of electron transfer quenching of triplet excited neutral Pd−tetraphenylporphyrin is investigated in a series of isotropic solvents and in a nematic crystalline one. Aromatic nitro compounds and quinones of different redox potentials are used as quenchers so that the quenching reaction is ex…
Thin films of Ce 1-x Y x O 2-y where x ranges from 0 to 0.5 have been coated onto glass substrates using an inorganic sol–gel approach at low temperature. The lattice parameters from powder diffraction measurements were calculated and shown to be very close to those previously reported. Crystallite size measurements i…
The frequency-dependence of experimentally-derived or point-wise ab initio calculated hyperpolarizability averages is often expanded up to fourth order in the frequencies using the dispersion formula X || (n) (ω1;...,ω n ) = X || (n) (0)(1 + A ω L 2 + B + ω L 4 + O (ω i 6)) with ω L 2 = Σ i ω i 2, where the coefficien…
Insoluble nonstoichiometric and stoichiometric complexes were formed as a result of reaction between polystyrene- block -polyacrylate anions (PS- b -PAA - ) and N -cetylpyridinium cations (C 16 Py + ) in aqueous media. In the presence of water the nonstoichiometric complexes with low content of surfactant represent sw…
Microfiltration of model solutions was conducted to identify the principal interacting species in foulant produced during membrane clarification of apple juice. Tannin and gelatin solutions did not foul microfiltration membranes, whereas both low-methoxy (LMP) and high-methoxy pectin (HMP) produced a fouling layer wit…
The gene for chorismate mutase (CM) from the archaeon Methanococcus jannaschii, an extreme thermophile, was subcloned and expressed in Escherichia coli. This gene, which belongs to the aroQ class of CMs, encodes a monofunctional enzyme (AroQf) able to complement the CM deficiency of an E. coli mutant strain. The purif…
This paper is the second in a two-stage exposition on phase separation in binary (AB) mixtures with simple chemical reactions, which involve only the components A and B of the mixture. In this paper, we present details of our modelling, which employs the master equation formalism, for a number of different reactions.…
The initiating ability of the potassium permanganate in the graft copolymerization of acrylonitrile onto starch was studied. The results indicate that the grafting parameters, such as concentrations of potassium permanganate, acrylonitrile, starch, and catalyst acids, all have significant effects on the graft copolyme…
Interdigitated capacitors have been fabricated on ferroelectric thin films of Sr0.5Ba0.5TiO3. These devices have been characterized at microwave frequencies from 50 MHz to 20 GHz, and have a 3.4:1 tuning range over a 1–40 V bias range. This is shown to originate from a relative dielectric constant tuning of 3.8:1. The…