Materials Literature
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Low temperature two-photon fluorescence excitation microscopy was used to obtain fluorescence spectra of single CdSe colloidal nanocrystals or quantum dots. The fluorescence spectra reveal large, 0.02 eV shifts of the peak emission wavelength on times of the order of 100 s were also observed in some instances. We attr…
It has been shown that the blue photoluminescence (PL) of porous silicon (PS) can be obtained simply from postanodization illumination by white light without any oxidation processes. The PS samples were formed on 5–6 Ω cm p-type (100) Si wafers. The anodization was carried out in an ethanoic HF solution at a current d…
We report the formation of self-assembling CdSe quantum dots during molecular beam epitaxial growth on ZnSe and ZnMnSe. Atomic force microscopy measurements on specimens with uncapped dots show relatively narrow dot size distributions, with typical dot diameters of 40±5 nm, and with a diameter-to-height ratio consiste…
The title radicals, C19H14N3, are arranged in columns along the b axis, in which the almost planar 1,2,4-triazin-4(1H)-yl ring and the phenyl ring on C3 of adjacent molecules lie alternately on top of one another. Within the array, the mean interplanar distance is 3.45 Å. However, the centers of the 1,2,4-triazin-4(1…
Static and dynamic dielectric properties were studied around the ferroelectric phase transition temperatures of PbHAsO 4 and PbHPO 4 . Typical Debye-type dielectric dispersions were observed in both of the ferroelectrics. Dynamic dielectric properties of the two ferroelectrics are very similar to each other. On the ot…
The elastic free energy of carbon nanotubes grown by iron-catalyzed decomposition of acetylene is introduced to describe the possible tubular shapes. The equilibrium shape equation can be obtained by the first variation of the elastic free energy of the slightly distorted tube. The model is consistent with both stable…
We present results of high-pressure--low-temperature studies of template synthesized polypyrrole. Thermopower measurements at ambient pressure show a linear temperature dependence, which supports the intrinsic metallic character of the samples. The dc conductivity follows the typical variable-range-hopping behavior at…
A theory for resistivity and magnetoresistance of ${\mathrm{LaMnO}}_{3}$-type degenerate ferromagnetic semiconductors is developed. The peak of resistivity not far from the Curie point ${\mathit{T}}_{\mathit{C}}$, which is absent in perfect crystals, is explained by a magnetization-dependent impurity scattering when t…
The title compound, μ-[(E)-1,3-di-η5-cyclopentadienyl-2-buten-1-one]bis(η5-cyclopentadienyliron) –Water (4/1), [Fe2(C5H5)2(C14H12O)].0.25H2O, has two independent [Fe2(C5H5)2(C14H12O)] molecules in the asymmetric unit. Pairs of one of these molecules form dimers linked by hydrogen bonds via a water molecule occupying e…
The effects of surface-tension anisotropy on interface morphology during the directional solidification of a binary alloy are studied. The long-wave evolution equation derived by Brattkus & Davis to describe growth near the absolute stability limit is generalized to include the effects of a surface tension wit…
Optical absorption, photoluminescence (PL), and electron paramagnetic resonance (EPR) data on unirradiated and UV-irradiated Ge-doped silica are reported. The analysis of the UV-induced effects shows the following facts: (i) both components of the 5-eV absorption band are partially bleached, as well as the PL excited…
The transient induced absorption and bleaching are examined in 10 nm size CuS nanocrystals embedded in polyvinylalcohol film. Partial surface oxidation of CuS nanocrystals produces a new near-IR-absorption band peaked at 1100 nm. The surface oxidized shell is supposed to form a midgap electron acceptor level and the n…
We have carried out a systematic search for the lowest energy structures of (AlP)N (N⩽6) clusters using density functional theory within the local density approximation. We employ a novel search strategy based on genetic algorithm to find the global minima of these clusters. This study reveals that (AlP)N alloy cluste…
Lithium fluoride stands apart from the other alkali halide crystals because of its good physical properties and the excellent thermal stability of the color centers. Among them the ${\mathrm{F}}_{3}^{+}$ after absorbing at \ensuremath{\sim}450 nm emits at \ensuremath{\sim}535 nm, with an unusual dependence on time, ex…
We report a detailed study of nanostructure fabrication and optical characterization of sub-μm-period, one-dimensional, Si grating structures. Nanoscale wall width structures were fabricated by combining laser interferometric lithography with anisotropic wet-chemical etching (KOH) and thermal oxidation. Structure wall…
Protein geranylgeranyltransferase type-I (GGTase-I) transfers a geranylgeranyl group from the prenyl donor geranylgeranyl diphosphate (GGPP) to the cysteine residue of substrate proteins containing a C-terminal CaaX-motif (a sequence motif of proteins consisting of an invariant Cys residue fourth from the C-terminus).…
The electronic band structure and the local screening effects of the transition-metal perovskites ${\mathrm{La}}_{0.65}{A}_{0.35}\mathrm{Mn}{\mathrm{O}}_{3}$ ($A=\mathrm{Ba}\mathrm{and}\mathrm{Ca}$) have been examined across the coupled magnetic-metallic phase transition using the techniques of angle-resolved photoemi…
The molecule Bcl was generated by chlorination of B(s) with both MgCl2 and SrCl2 in a heated effusive beam source, and identified by mass spectrometry. Gaseous equilibria in the B–Mg–Cl and B–Sr–Cl systems were studied in the regions 1350–1600 K and 1760–1830 K, respectively, and the dissociation energy D0°(Bcl)=121.3…
Direct current (dc) resistivity studies have been made on two series of Ni–Zn–Sc ferrites with varying concentrations of zinc and scandium to estimate the effects of composition, temperature, and applied electric field. The resistivity has been found to increase with the increase in scandium/zinc content in both the s…
Optical and electrochemical properties of vanadium pentoxide (V2O5) films prepared by sol-gel method from organic and inorganic precursors were studied. The organic gel was obtained by hydrolysis and polycondensation of vanadium isopropoxide dissolved in isopropanol. The inorganic gel was prepared from aqueous solutio…