Materials Literature
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A new phosphor in the system K2SO4 Na2SO4 doped with Eu is reported. This is shown to be at least thrice as sensitive as the conventional CaSO4: Dy phosphor used in the thermoluminescence dosimetry of ionizing radiations. Characterization of this phosphor using XRD, PL, and TL techniques is described.
The increase in photoluminescence and thermoluminescence of CaSO4: Dy TLD phosphor by co-doping with Ce or P is described. Cerium is found to sensitize the PL but not the TL. P doping helps incorporation of Dy in higher concentration. PL increases by 150% while the increase in TL is about 50%. It is claimed that the C…
Many experimental works report that the presence of water trees lowers the voltage needed for the initiation of dielectric breakdown in polyethylene. The influence of water trees on the dielectric breakdown is generally related to their length. Here, in addition to this spatial property, we consider the extinction of…
The negative-ion fractions of oxygen directly recoiled from a Ni{100}c(2\ifmmode\times\else\texttimes\fi{}2)-O and a NiO{100} surface have been measured as a function of the crystal azimuthal angle and the recoiled atom exit trajectory from the surface. The data exhibit a pronounced angular dependence of the ion fract…
Crystal structure of LiNH 4 SO 4 was refined in phase II (room temperature) and phase III (190 K) by the use of X-ray diffraction intensity with including hydrogen atoms. The least-squares calculations converged with residual parameter R =0.0362 and 0.0378 for phases II and III, respectively. At room temperature, ther…
We have developed a theory of photoemission from III-V compound semiconductors within the one-step model and discuss the effect of transition-matrix elements, final states, and the surface barrier on the energy distribution of photoelectrons. As a prototype the (110) surface of GaAs is studied, and theoretical spectra…
The processes of formation and crystallization of thin films of SrTiO3 prepared by the method of metallo-organic decomposition have been studied with particular emphasis on the relationship between the thermal decomposition of the metallo-organic precursors and the eventual epitaxial alignment of the crystallized film…
The interpretation of the infrared and Raman spectra of polyconjugated polyfuran prepared by electroreduction of 2,5-dibromofuran is presented as the result of lattice dynamical calculations. Geometries and vibrational force fields are derived from semiempirical calculations carried out on oligomers and the parameters…
Abstract Graft polymerization of anionic and cationic monomers was performed onto the surface of poly(ethylene terephthalate) (PET) film with a simultaneous UV irradiation method, but using no photo‐sensitizer. To effect graft polymerization, the PET film was immersed in an aqueous solution containing a monomer and pe…
Schottky barrier formation of metal contacts deposited on diamond (111) and (100) surfaces was investigated. Three different metals (Au, Al, and Ti) were studied because of their different chemical reactivity with C, i.e., Au being a nonreactive metal, Al a weak carbide-forming metal, and Ti a strong carbide former. B…
We present a theory of surface enhanced Raman scattering (SERS) that gives a response enhancement of up to ten orders of magnitude for pyridine on silver. The signal obtained depends on the laser frequency and is consistent with available experimental data. Our theory emphasizes the effect of the molecule itself on th…
A semiempirical tight-binding method was used to calculate the band structures of ${\mathrm{Si}}_{1\mathrm{\ensuremath{-}}\mathit{x}}$${\mathrm{Ge}}_{\mathit{x}}$ alloys coherently grown on (001)-, (111)-, and (110)-oriented ${\mathrm{Si}}_{1\mathrm{\ensuremath{-}}\mathit{y}}$${\mathrm{Ge}}_{\mathit{y}}$ substrates. T…
Photoelectron spectra resulting from sequential or simultaneous absorption of two photons have been studied at four different silicon surfaces. To study energy-relaxation lifetimes, one laser pulse populates conduction states and normally unoccupied surface states, from which photoelectrons are excited by the second p…
We present a self-consistent-field structure for the thermodynamic description of concentrated solutions of liquid-crystal polymers. The polymers are assumed to be locally stiff but capable of curvature over large distances. The formulation of the chain geometry is that of a wormlike polymer, but the final analysis is…
We report optical-absorption, photoluminescence (PL), and picosecond photoinduced absorption (PA) decay in films of poly-3-hexyl-thiophene at pressures up to 80 kbar. The spectral bands redshift nonlinearly with pressure and the PL intensity decreases markedly. Thermochromic transitions are completely inhibited at pre…
The electronic structures of 15 models of periodic graphitelike carbon surfaces (PGCS) with negative Gaussian curvatures are studied by a first-principles method. These models, which consist of P, D, and G surfaces of PGCS and range from 24 to 216 atoms in the unit cell, have different structural characteristics. Resu…
We report ab initio molecular-dynamics simulations of small aluminum clusters, ${\mathrm{Al}}_{\mathit{n}}$ of n=2--6 and 12, 13, 55, and 147, using the density-functional, local-orbital method of Sankey. Equilibrium structures and total energies were calculated and compared with experiment and the predictions of othe…
A DNA polymer with hundreds or thousands of base pairs is modeled as a thin elastic rod. To find the equilibrium configurations and associated elastic energies as a function of linking number difference (ΔLk), a finite element scheme based on Kirchhoff’s rod theory is newly formulated so as to be able to treat self-co…
We have made a comparative theoretical study of the most common forms of unhydrogenated amorphous carbon (\ensuremath{\alpha}-C), namely, of the dense, diamondlike phase and the low-density evaporated \ensuremath{\alpha}-C (e-C). Emphasis is given to the connection among the structure, energetics, and stability of the…
Diamond was deposited on synthetic graphite, highly oriented pyrolytic graphite and on substrates covered with graphite powder. Scanning electron microscopy and transmission electron microscopy were used to examine the samples. A strong preference for nucleation of diamond on the edges of the graphite sheets was obser…