Materials Literature
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We report the observation of the anisotropic linear polarization of porous Si photoluminescence measured in two excitation geometries. In the normal excitation geometry (exciting beam normal to the sample (100) surface) linear luminescence polarization of as much as 20% is seen parallel to the excitation polarization.…
Using an aluminum–porous p+ silicon junction, we have realized a sensor which dc current increases up to two orders of magnitude in the presence of ammonia, as for a series of various gases. To interpret quantitatively this phenomenon, we assume that the conductivity is governed by the width of a channel resulting fro…
For the first time we present results of ab initio calculations of the structural and electronic properties of heterocrystalline combinations of a cubic (3 $C$) and a hexagonal ( $\mathrm{pH}$, $p\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}2,4,6$) polytype of SiC, the material exhibiting the most pronounced pol…
Theoretical and experimental results are presented providing evidence for fast Auger recombination in silicon nanocrystallites. Calculations give nonradiative lifetimes in the 1 ns range. Luminescence experiments on porous silicon exhibit a saturation at high excitation power. The Auger effect gives a natural explanat…
The domain structure of ferroelastic BiVO 4 crystals was investigated by X-ray diffraction, nuclear magnetic resonance, optical polarizing microscopy, transmission electron microscope, and electron diffraction techniques. From these results, it is found that the BiVO 4 crystals have only prominent W walls and no non-p…
The projection of the eigenfunctions obtained in standard plane-wave first-principle calculations is used for analyzing atomic-orbital basis sets. The "spilling" defining the error in such a projection allows the evaluation of the quality of an atomic-orbital basis set for a given system and its systematic variational…
Optical components are usually classified into diffractive and refractive elements. In this classification, refractive components are defined as elements that are sufficiently described by geometrical optics. For micro-optics this distinction is very often not applicable. Our goal is to understand which parameters con…
The dynamics of foam drainage (free, forced and pulsed) is monitored by the determination of local liquid density using a vertical array of capacitors. Liquid profiles are obtained for various drainage experiments. The merging of two solitary waves is in good agreement with theoretical predictions. Such capacitance me…
The numerical solutions of binary-phase (0, π) gratings for one-dimensional array illuminators up to 32 are presented. Some fabrication errors, which are due to position-quantization errors, phase errors, dilation (or erosion) errors, and the side-slope error, are calculated and show that even-number array illuminator…
Uncooled IR focal plane arrays employ thermal detection mechanisms including the resistive bolometric, pyroelectric, and thermoelectric effects. Readout electronics are incorporated at each pixel. Two thermal isolation structures are possible: hybrid and monolithic. The ultimate limit to the performance is set by temp…
Photoelectron spectroscopy of CuO−2 has been studied at three detachment wavelengths: 532 nm, 355 nm, and 266 nm. Vibrationally resolved spectra for two distinct isomers are observed: the Cu(O2) complex and the copper dioxide molecule. The Cu(O)2 complex has an electron affinity (EA) of 1.503 (10) eV with a ground sta…
Ordering at short-length scales is a universal feature of the glassy state. Experiments on boron oxide and other materials indicate that ordering on mesoscopic-length scales may also be universal. The high-resolution nuclear magnetic resonance (NMR) measurements of oxygen in boron oxide glass presented here provide ev…
A simple method is presented for calculating approximate static and dynamic vibrational hyperpolarizabilities. It involves determining electrical properties in the presence of a static field with and without geometry optimization. This method is readily applicable to all tensor components of a general polyatomic molec…
Various size-consistent approaches to the calculation of molecular hyperpolarizabilities are analyzed based on the double perturbation theory. General equations for the nth-order response property with respect to an external time-independent field are derived on the basis of the Rayleigh–Schrödinger perturbation theor…
Three supramolecular bischromophoric systems featuring zinc(II) and iron(III) porphyrins have been synthesized to evaluate the relative magnitudes of electronic coupling provided by hydrogen, sigma, and pi bonds. Laser flash excitation generates the highly reducing singlet excited state of the (porphinato)zinc chromop…
We develop a lattice gas model for the nonequilibrium dynamics of microemulsions. Our model is based on the immiscible lattice gas of Rothman and Keller, which we reformulate using a microscopic, particulate description so as to permit generalisation to more complicated interactions, and on the prescription of Chan an…
We present a microscopic derivation, without electrodynamical assumptions, of $B(x,y,H(t))$, $M(H(t))$, and $J_c(H(t))$, in agreement with experiments on strongly pinned superconductors, for a range of values of the density and strength of the pinning sites. We numerically solve the overdamped equations of motion % dy…
Abstract The mechanism of radiation vulcanization of natural rubber with 2‐ethyl hexyl acrylate (2EHA) monomer was investigated using electron spin resonance spectroscopy and nuclear magnetic resonance (NMR) spectroscopy. The primary radicals formed in the arcylate molecule were found to abstract the allylic hydrogens…
Abstract There kinds of dimeric aluminates (2DH‐306, 2DH‐324, and 2DH‐335) have been used for surface modification of calcium carbonate (CaCO 3 ) particles. The dimeric aluminates were shown to have an appreciable coupling effect at the interfaces between the light calcium carbonate (L‐CaCO 3 ) and polypropylene (PP)…
Abstract Epoxy functionalized siloxanes (EFS) are a novel class of UV curable monomers that can be rapidly photopolymerized to give transparent coatings and composites. Thin films of these materials have been subjected to low Earth orbit exposure to atomic oxygen (AO) aboard the space shuttle. It was found that UV cur…