Materials Literature
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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.…
In this study, cell coarsening in plastic foaming is investigated through numerical simulation. Cell coarsening occurring in two adjacent bubbles of different sizes in a finite volume of polymer melt is considered to be representative of the whole foaming system. A quadratic triangle-based finite element analysis with…
Abstract The extent of flame propagation of electric cables in the FM Global intermediate‐scale parallel panel test (PPT) using a 60 kW sand burner has been correlated with a dimensional fire propagation index (FPI,)[(m/s 1/2 )/(kW/m) 2/3 ] derived from ignition and vertical propagation tests in small‐scale ASTM E‐205…
We studied the electro-optical property and photorefractive effects in a semiconductor CdSe nanorod doped neamtic liquid crystal [NLC] system. The nonlinear index coefficient is measured to be <i>n</i><sub>2</sub>=2.05×10<sup>−2</sup><i>cm</i><sup>2</sup>/<i>W</i>, which is 10 times larger than that of an equiva…
The photophysical properties of excited singlet states of zinc tetra-(p-octylphenyl)-porphyrin in 5-25-nm-thick films spin-coated onto quartz slides have been investigated by optical spectroscopy. Analysis of the polarized absorption spectra using a dipole-dipole exciton model with two mutually perpendicular transitio…
Reactor builders think that fossil fuel prices and climate fears will revive nuclear power. But will new reactor designs overcome the concerns of utilities and the public?