Materials Literature
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We examined the steady state and time resolved luminescence spectral properties of two types of CdS nanoparticles. CdS nanoparticles formed in the presence of an amine-terminated dendrimer showed blue emission. The emission wavelength of these nanoparticles depended on the excitation wavelength. The CdS/dendrimer nano…
We demonstrate the tailoring of highly oriented pyrolytic graphite (HOPG) to obtain uniformly sized islands of up to several microns in size. There has already been some research on manipulating individual sheets on HOPG surfaces with scanning probe microscope tips; such sheets were obtained either accidentally or wit…
Here, we report the use of amine-terminated poly(amidoamine) (PAMAM) dendrimers as adhesion promoters between vapor-deposited Au films and Si-based substrates. This method is relatively simple, requiring only substrate cleaning, dipping, and rinsing. Proof of concept is illustrated by coating glass slides and single-c…
We present exact solutions of the non-linear {\sc bcre} model for granular avalanches without diffusion. We assume a generic sandpile profile consisting of two regions of constant but different slope. Our solution is constructed in terms of characteristic curves from which several novel predictions for experiments on…
Shape-controlled gold nanoparticles were synthesized using a novel ultraviolet irradiation technique at room temperature. The very slow ultraviolet irradiation photoreduction process may favor the formation of the shaped gold nanoparticles. It was found that not only the concentration of gold cations and the irradiati…
Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” opt…
The effects of the cation symmetry and packing on the mixed-valence state of binuclear ferrocene derivatives are discussed separately by paying attention on the differences between the racemic and ( S, S ) samples and between the salts from hexane and from dichloromethane in 1‘,1‘ ‘‘-bis(2-methylbutyl)-1,1‘ ‘-biferroc…
The topography of the multidimensional potential energy landscape is receiving much attention as a useful object of study for understanding complex behavior in condensed-phase systems. Examples include protein folding, the glass transition, and fracture dynamics in solids. The manner in which a system explores its und…
Poly(ethylene terephthalate) (PET) copolymers containing 2,6-anthracenedicarboxylate structural units are modified by Diels−Alder reactions with maleimides. Low molecular weight bis(maleimide)s are used to chain extend and cross-link the polymers. The resulting materials were characterized by 1 H NMR, UV−vis, DSC, and…
ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTDirected Growth of Free-StandingSingle-Walled Carbon NanotubesAlan M. Cassell, Nathan R. Franklin, Thomas W. Tombler, Emory M. Chan, Jie Han, and Hongjie DaiView Author Information Department of Chemistry, Stanford University Stanford, California 94350 NASA Ames Resear…
One of the important problems of high-temperature superconductivity is to understand and ultimately to control fluxoid motion. We present the results of a new technique for measuring the pressure dependence of the transition to superconductivity in a diamond anvil cell. By measuring the third harmonic of the {\it ac}…
The H-T phase diagram of CuGeO$_3$ has been determined, for different values of the hydrostatic pressure, utilizing optical absorption spectroscopy on the Cu$^{2+}$ d-d transitions. It is shown that the intensity of the related zero phonon line transition is very sensitive to the local environment of Cu$^{2+}$, allowi…
The oxidation behavior of porous silicon (PS) has been found to be related to illumination during etching. The autocatalytic oxidation behavior at room temperature arises from the unrelaxed surface induced by the preparation under illumination and can be removed using thermal treatment in a nitrogen atmosphere. The ef…
We have studied the kinetics of phase separation in a colloid-polymer mixture. The evolution of initially homogeneous samples as they separate into coexisting colloidal gas, liquid, and crystal phases was investigated by time-lapse video recording. Distinct kinetic regimes were found, the existence and character of wh…
Neutron powder diffraction experiments on layered manganites ${\mathrm{La}}_{2\ensuremath{-}2x}{\mathrm{Sr}}_{1+2x}{\mathrm{Mn}}_{2}{\mathrm{O}}_{7}\phantom{\rule{0ex}{0ex}}(0.32\ensuremath{\le}x\ensuremath{\le}0.40)$ show that coherent lattice anomalies observed at the Curie temperature (lattice parameters, Mn-O bond…
A polarization-insensitive, electrically tunable Fabry-Perot filter (FP) with a nematic liquid crystal (NLC) is demonstrated in an axially symmetrical configuration. Due to the axial symmetry, the wavelength-selection property of the FP filter is completely independent of the polarization state of the input beam in th…
A diamond detector type 60003 (PTW Freiburg) was examined for the purpose of dosimetry with 4-20 MeV electron beams and 4-25 MV photon beams. Results were compared with those obtained by using a Markus chamber for electron beams and an ionization chamber for photon beams. Dose distributions were measured in a water ph…
We have synthesized nanoparticles of ZnS doped with Mn for potential use as cathodoluminescent phosphors in field-emission displays (FEDs). We show that the cathodoluminescent efficiency of particles ⩽100 nm in diameter is within 40% of that of a commercial (micron-sized) phosphor when the electron-beam energy ranges…
A microscopic model for polarization fatigue in ferroelectric perovskites based on dipolar defects formed by the combination of oxygen vacancies and impurity metal ions is presented. The binding energy of an oxygen vacancy to a Pt impurity in $\mathrm{PbTiO}{}_{3}$ is calculated to be $\ensuremath{\sim}2.9\mathrm{eV}$…
Measurements of photoluminescence (PL) from composites of silica nanoparticles (the primary particle size 7 and 15 nm) as a function of heat treatment temperature show that the PL results from hydrogen-related species and thermally produced structural defects. The PL was induced by an ArF or Nd:YAG (yttrium–aluminum–g…