Materials Literature
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We have measured low-temperature size-selective photoluminescence excitation spectra of high-quality InP quantum dots prepared by collodial chemistry. A set of samples with mean emission energies in the range from 1.9 to 2.2 eV was investigated. All samples have a size distribution of about 10%, resulting in an inhomo…
The upconversion luminescence of a ${\mathrm{Dy}}^{3+}$-doped system is presented and analyzed. ${\mathrm{CsCdBr}}_{3}:x%$ ${\mathrm{Dy}}^{3+}$ ($x=0.2,$1,5) was synthesized and grown as crystals using the Bridgman technique. ${\mathrm{Dy}}^{3+}$ ions preferentially enter this host as charge-compensated dimers. Due to…
Electron, hole, and exciton states of multishell CdS/HgS/CdS quantum-dot quantum-well nanocrystals are determined by use of a multiband theory that includes valence-band mixing, modeled with a six-band Luttinger-Kohn Hamiltonian, and nonparabolicity of the conduction band. The multiband theory correctly describes the…
The use of a column of steadily drained foam as a sample of wet foam is limited by flow instability as the liquid fraction is increased. We report a study of this instability, which takes the form of a convective roll of bubble motion at a value of liquid fraction roughly half that of the wet foam limit at which a sta…
The functionally related amidohydrolases, including D-hydantoinases, dihydropyrimidinases, allantoinases and dihydro-orotases, share a similar catalytic function of acting on the cyclic amide ring. We aligned 16 amidohydrolases by taking account of the conservative substitution and found a number of highly conserved r…
Indium tin oxide thin films consisting mainly of whiskers have been deposited on glass by electron beam evaporation. Low deposition rates (35 Å/min) and substrate temperatures in the 120–400 °C range were used. Morphology by scanning electron microscopy, crystal structure, energy dispersive analysis of x-rays, and x-r…
An experimental investigation of the in situ electrical conductivity of Wesgo Al995 polycrystalline alumina at approximately 450 °C has been performed at the high flux beam reactor at Brookhaven National Laboratory. The measured radiation induced conductivity (RIC) was about 10−8 S/m at an ionizing dose rate of 6000 G…
Considering interchain interaction and the intrachain next-nearest-neighbor hopping interaction, within the self-consistent-field Hartree–Fock approximation, we deal with two neighboring organic ferromagnetic chains. We take into account the π-electrons, the Hubbard repulsion, and antiferromagnetic correlation between…
We present evidence for a biexciton state in a molecular aggregate. Femtosecond pump-probe spectroscopy of the $H$ aggregate of an epitaxially grown trivalent metal-halogen-phthalocyanine gives distinct photoinduced absorptions to a continuum of two-exciton states and to a bound biexciton state. No signature of the bi…
Color shift and gray scale reversal for very large viewing angles are analyzed theoretically for in-plane switching. It follows that the color shift depends on the change of the effective birefringence dΔn, whereas gray scale reversal depends on the effective angle between the polarizers and the liquid-crystal directo…
The density functional theory (DFT), semiempirical molecular orbital calculations, and π-orbital axis vector (POAV) analysis are used to study the energetics and geometries of carbon nanoconic tips. The tip models are formed by introducing two to five pentagons into a graphene network corresponding to experimentally o…
First principles calculations were performed for the structural properties of superhard materials, hexagonal β-Si3N4, β-C3N4, and two model structures of β-Si2CN4 and β-SiC2N4. Bulk modulus and lattice constants a and c have been obtained by fitting the total energy calculations to the Birch equation of state. As more…
Cholesteric liquid crystal displays employ cells consisting of parallel glass plates which have indium-tin-oxide coating as the electrode and polyimide as the alignment layer. We have performed a systematic study of the reflections from the interfaces and the liquid crystal. We measured the reflection spectra using va…
Results of quantum-chemical ab initio cluster calculations for the end-on and side-on adsorption of ${\mathrm{N}}_{2}$ on the coordinately unsaturated Ti atoms of the (110) surface plane of ${\mathrm{TiO}}_{2}$ (rutile) are reported. A large number of cluster models for the Ti adsorption site is investigated; the ${\m…
Stability of the polarization in a thin ferroelectric film on a semiconductor is theoretically investigated using an insulating homogeneous Ginzburg–Landau theory. Dependence of the stability on various parameters such as the ferroelectric thickness, the materials (BaTiO3, KNbO3, PbTiO3, Bi4Ti3O12), the interfacial de…
According to Kao’s model of electrical discharge and breakdown in condensed insulating materials, charge carrier injection from electrical contacts and subsequent dissociative trapping, and recombination play a decisive role in the breaking of polymer chains and the creation of free radicals or low-weight molecules, a…
The dissociation of CO on size-distributed Rh particles supported on a thin alumina film has been studied with high resolution X-ray Photoelectron Spectroscopy (XPS) and X-ray Absorption Spectroscopy (XAS). Adsorbed CO dissociates upon heating to temperatures above 300 K. The dissociation activity is dependent on the…
The techniques of x-ray diffraction, x-ray photoelectron spectroscopy (XPS), Auger analysis, and transmission and scanning transmission electron microscopy (TEM) have been applied to the analysis of thin films of Pb(Zr0.30Ti0.70)O3 (PZT30/70) deposited at low temperatures (510 °C) by a sol–gel process onto Pt/Ti elect…
The electronic and ionic contributions to the overall dielectric constant of fluorinated SiO2 films deposited in SiF4 and O2 plasmas were quantified from the refractive index measured by in situ spectroscopic ellipsometry in the visible-to-UV range and the infrared spectra taken by in situ attenuated total reflection…
The optical transmission of the recently discovered switchable yttrium hydride films is determined spectroscopically as a function of hydrogen content. This is done during electrochemical loading of Pd-capped Y film electrodes, thereby continuously changing the hydrogen concentration. The effect of the Pd cap layer on…