Materials Literature
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Single crystal, silver particles of 215 +/- 10 nm size were synthesized in solution using the hydrogen reduction method and were characterized by UV-visible extinction spectroscopy and electron microscopy. The extinction spectra reveal the presence of higher order multipoles of the plasmon resonance, such as quadrupol…
We report local-field-enhanced light emission from silicon nanocrystals close to a film of nanoporous gold. We resolve photoluminescence as the gold-Si nanocrystal separation distance is varied between 0 and 20 nm and observe a fourfold luminescence intensity enhancement concomitant with increases in the coupled silic…
The barrier properties of polymer-clay nanocomposites, with far less inorganic contents of layered-silicate fillers, are remarkably superior to those of neat polymers or their conventional counterparts. A simple renormalization group model is proposed to assess the influence of geometric factors (such as aspect ratio,…
A volatility diagram was calculated for temperatures of 1000, 1800, and 2500 K to understand the oxidation of ZrB 2 . Applying the diagram, it can be seen that exposure of ZrB 2 to air produces ZrO 2 (cr) and B 2 O 3 (l) over the temperature range considered. The pressure of the predominant vapor species was predicted…
We have synthesized artifact-free bulk nanocrystalline copper samples with a narrow grain size distribution (mean grain size of 23nm) that exhibited tensile yield strength about 11 times higher than that of conventional coarse-grained copper, while retaining a 14% uniform tensile elongation. In situ dynamic straining…
We show that long-range ferroelectric and incommensurate magnetic order appear simultaneously in a single phase transition in Ni3V2O8. The temperature and magnetic-field dependence of the spontaneous polarization show a strong coupling between magnetic and ferroelectric orders. We determine the magnetic symmetry using…
TbMnO3 is an orthorhombic insulator where incommensurate spin order for temperature T(N)<41 K is accompanied by ferroelectric order for T<28 K. To understand this, we establish the magnetic structure above and below the ferroelectric transition using neutron diffraction. In the paraelectric phase, the spin structure i…
Electrochromic (EC) materials are used in "smart" windows that can be darkened by applying a voltage across an EC stack on the window. The associated change in refractive index (<i>n</i>) in the EC materials might allow their use in tunable or temperature-insensitive Fabry-Perot filters and transmissive-spatial-light-…
Fluorescence detected magnetic resonance (FDMR) has been applied to approximately 25-nm-thick porphyrin films, containing ordered domains of zinc tetra-(p-octylphenyl)-porphyrin (ZnTOPP) spin-coated onto quartz slides. Illuminating the films at 1.4 K with 457.9-nm light from a continuous wave Ar(+) laser produces at l…
We analyzed the experimental time-of-flight data for photoinjected holes in two smectic liquid crystals, the first consisting of a phenylnaphthalene derivative 8PNPO12, and the second consisting of a biphenyl derivative 6OBP6. We fit the time of flight transients for different electric field strengths to a multiple tr…
The sensitivity of photonic bandgap (PBG) structures to the environment makes them suitable for sensing applications. In this study, we describe how 1-D and 2-D PBG devices can be used for sensing biological matter, from small DNA segments to larger proteins. Our work focuses on using the tunability of silicon PBGs up…
We present laboratory measurements of the reduction in UV-to-visible/IR reflectivity (1200Å - 10,000Å) of optical surfaces due to 50Å - 500Å deposited layers of out-gassed molecular contaminants from 9 commonly used spacecraft/space instrument materials that include Apiezon-L hi-vacuum grease,…
The lattice effects on the magnetic and transport properties in La<sub>0.67-x</sub>Gd<sub>x</sub>Sr<sub>0.33</sub>CoO<sub>3</sub> series are studied. The introduction of smaller Gd<sup>3+</sup> ions leads to an enhanced mismatch between the La-O layer and the CoO<sub>2</sub> layer and a decrease of the tolerance facto…
Deoxyribonucleic acid (DNA), extracted from salmon sperm through an enzyme isolation process, is precipitated with a surfactant complex, cetyltrimethl-ammonium chloride (CTMA), for application as a nonlinear optical (NLO) material. Preliminary characterization studies suggest DNA-CTMA may be suitable for use as the ho…
The threat of global warming and high fossil fuel prices have inspired talk of a revival of nuclear power, but skeptics say it is a poor investment and a worse security risk. This special focus section also discusses nuclear power9s global reach, new reactor designs, and plans for waste repositories.
We developed electrically-switchable two-dimensional diffractive gratings with periodic refractive index modulation arising from layers undulations in cholesteric liquid crystal. Two-dimensional layer undulations occur above the threshold voltage when a planar cholesteric cell of thickness much larger than the cholest…
Abstract A simple chemical bath deposition (CBD) technique with ultrasonication has been developed and successfully used to deposit cadmium sulfide (CdS) thin films onto glass substrates from a bath containing cadmium salt and thiourea. The structural and electrical properties of the CdS films were investigated. From…
A light switch: The mechanism of transmission of the photoinduced torsional strain along a cyclic peptide, incorporating a biomimetic photochemical switch, is resolved by quantum mechanics/molecular mechanics and molecular dynamics simulations. The excited-state cis→trans motion of the switch does not affect the confo…
Nano-optical devices are raising more and more interest for a variety of applications. From single molecule detection at high molecular concentration by Fluorescence Correlation Spectroscopy (FCS) through optical multiplexing with photonic crystal structures into the exciting field of negative index of refraction mate…
Electrical and thermal conductivities of metal nanoparticles and their aggregates are important for many device applications involving nanomaterials. In this work, the electrical conductivity of gold nanoparticle aggregates has been measured and found to be a useful probe of the surface chemistry of the nanoparticles.…