Materials Literature
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A simple quantum-sphere model for small metallic particles of arbitrary size embedded in nonabsorbing dielectric media is used to compute the real and imaginary parts of the dielectric function. The quantum confined electrons can be considered as nearly free electrons but having discrete energy levels. The dielectric…
An experimental study of the local electronic structure of Ce-doped yttria (2% and 5% at.) was performed using photoelectron and x-ray-absorption spectroscopies (XPS and XAS). The local atomic arrangement in the solid solutions is well represented by an eightfold oxygen coordination around Ce atoms, with a Ce-O distan…
The swelling pressure of randomly crosslinked polymer networks is related to the structural properties of the crosslink topology. Using the assumption that the network structure exhibits fractal properties within the correlation length ξ, a scaling relation between the swelling pressure and the polymer volume fraction…
The symmetry properties of chiral monolayered carbon nanotubes, along with the method of zone-folding, are used to study their electronic and lattice properties. The energy bands and phonon modes are classified according to the irreducible representations of the 1D periodicity of the chiral nanotubes.
First-principles methods are used to study diamondlike amorphous carbon. Several structural models are introduced, and the topological, electronic, and vibrational properties are discussed. We explore the nature of defects in the amorphous network, and particularly the atomistic origin of the virtually defect-free opt…
A systematic study is presented on the optical and structural transformations induced in amorphous Ge1−xSbx alloys with Sb contents in the 0.71≤x≤0.91 range by irradiation with 250 ns laser pulses. The results show that only those films richer in Sb than the eutectics (x=0.85) show appreciable optical contrast upon ir…
The optical spectroscopic properties of Mn5+ doped into ten host lattices have been studied. The influence of both chemical variation [phosphates(V), arsenates(V), and vanadates(V)] and structural variation (spodiosites, apatites, and Li3PO4-type salts) on the luminescence properties is studied in detail. By varying t…
The angular dependence of magnetic Barkhausen noise (MBN) on eight surfaces through the thickness of a 2% Mn steel pipeline sample was investigated. The MBN signal was analyzed by integrating the square of the MBN voltage signal with respect to the time axis. The resulting value, referred to as the MBN energy signal,…
The localized character of the 3d electrons in the antiferromagnetic oxides NiO(100) and CoO(100) has been studied with electron energy-loss spectroscopy at primary energies between 20 and 1200 eV. The spectra of both charge-transfer compounds exhibit weak but sharp loss structures within the insulating gap region due…
Using time-resolved digital video microscopy, we have tracked the reemergence of order in charge-stabilized colloidal crystals which have been shear melted into isotropic fluids. Crystallization is heterogeneously nucleated by the smooth walls of the sample container. This process is analogous to the solidification of…
The $^{5}$${\mathit{D}}_{0\mathrm{\ensuremath{-}}}^{7}$${\mathit{F}}_{0}$ transition mechanism has been investigated for the ${\mathrm{Eu}}^{3+}$ ion in two kinds of oxide glasses, polyvinyl alcohol film, and ${\mathrm{Y}}_{2}$${\mathrm{O}}_{2}$S crystal powder, from the analysis of the laser-induced fluorescence spec…
Core-level and valence-band photoemission studies of films of La@${\mathrm{xaC}}_{82}$ and ${\mathrm{C}}_{82}$ demonstrate charge transfer from La to the fullerene cage and the formation of a nonmetallic solid with the uppermost band centered 0.64 eV below the Fermi level. Comparison to results for ${\mathrm{C}}_{82}$…
Electron differential inverse mean free paths for volume-plasmon excitations and differential probabilities for surface-plasmon excitations have been calculated using dielectric response theory. A model dielectric function which satisfied sum rules and agreed with optical data was established for these calculations. I…
Absorption and emission spectra, along with lifetime measurements, of Dy(3+) in Ge-Ga-S glasses are reported. Fluorescence is observed at 1.3, 1.8, and 2.9 microm. A Judd-Ofelt analysis is performed to determine branching ratios and quantum efficiencies. The hypersensitive transition (6)F(11/2) ? (6)H(15/2) at 1.3 mic…
We have studied the mechanism of visible photoluminescence (PL) from surface-oxidized Si crystallites of 3.7 nm diameter. Under intense laser-pulse illumination, two PL bands are clearly observed: a fast-decay blue-green PL band and a slow-decay red PL band. Time-resolved PL-spectrum measurements indicate that carrier…
The luminescence quenching of Er in crystalline Si at temperatures between 77 and 300 K is investigated. Samples were prepared by solid-phase epitaxy of Er-implanted amorphous Si layers with or without O codoping. After epitaxial regrowth at 620 \ifmmode^\circ\else\textdegree\fi{}C, thermal annealing at 900 \ifmmode^\…
We have investigated visible photoluminescence excited by Ar-ion laser (488 nm, 2.54 eV) at room temperature from Si+-implanted silica glass, as-implanted and after subsequent annealing in vacuum. We found two visible luminescence bands: one peaked around 2.0 eV, observed in as-implanted specimens and annealed complet…
We show that ideal reflection filters can be designed by combining guided-mode resonance effects in waveguide gratings with antireflection effects of thin-film structures. Since the guided-mode resonance effect overrides the antireflection effect this filter provides a symmetrical line shape with near-zero reflectivit…
An extended theoretical approach for calculating the 1s-1s electronic transition in spherically layered semiconductor quantum dots is presented. The extension over the common effective-mass approximation includes the implementation of the Coulomb interaction and finite potential wells at the particle boundaries. The c…
We present self-consistent ab initio total-energy calculations of the equilibrium relaxed structures and surface energies of the stoichiometric (1\ifmmode\times\else\texttimes\fi{}1) (110), (100), (001), and (011) surfaces of ${\mathrm{TiO}}_{2}$. The relaxations of atoms on these surfaces are found to be substantial,…