Materials Literature
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A new discrete-channel tunable Lyot filter that uses ferroelectric liquid-crystal (FLC) smectic C* wave plates is described and demonstrated. The device is tuned by changing the retardation of each birefringent element. This is achieved by electrically rotating the FLC wave plates in each stage by 45 degrees , which e…
X-ray-absorption spectra of a-Si and a-Si:H at the Si K edge are reported. By means of a nonstandard data-analysis procedure, we show that the fine-structure spectrum contains, besides the first-shell single-scattering extended x-ray-absorption fine-structure (EXAFS) signal, a higher-frequency contribution as well. Ve…
Light and small angle neutron scattering results are presented for a series of poly(dimethyl siloxane) (PDMS) gels, cured in the dry state by endlinking with a trifunctional crosslinking agent, ethyl triacetoxy silane (ETAS). For gels swollen in octane, the scattered light and the smallest angle neutron response are d…
We present a method to calculate both the thermal and the structural damping of the multiple-scattering (MS) contributions to the x-ray-absorption coefficient. In the thermal case the correlation matrices between the coordinates of the atoms connected by MS paths are calculated, in the harmonic approximation, using th…
Using a full-potential linear-muffin-tin-orbital method (LMTO-FP), ab initio calculations of the \ensuremath{\Gamma}-point phonon spectrum and elastic properties of the copper halides CuF, CuCl, CuBr, and CuI (and for purpose of comparison of Si, ZnSe, and ZnTe) were performed. Our results for the TO(\ensuremath{\Gamm…
We study the transmission and frequency spectra of phonons in aperiodic Thue-Morse superlattices. Calculations based on the transfer-matrix method predict rich structures of the transmission dips and frequency gaps, and their basic properties are well described by the superlattice-structure factors that we derive. The…
Photoemission measurements were performed on thick silver films vapor deposited under ultrahigh-vacuum conditions onto cold or warm substrates and on samples subsequently annealed. Laser powers were adjusted so that linear photoemission is produced with 4.5-eV (above-threshold) photons and quadratic photoemission with…
The general problems and limitations of photoaddressed liquid crystal spatial light modulators (SLMs) are discussed, and experimental results are presented. A GaAs wafer photoaddressed nematic liquid crystal SLM is described in detail with experimental results. The edge enhancing or differentiating SLM is discussed, a…
The pressure derivatives and uniaxial strain derivatives of the elastic constants of copper are calculated using the embedded-atom method, and the results are in good agreement with experiment. Also, the elastic constants of a \ensuremath{\Sigma}5 twist grain boundary [with (100) boundary planes] are calculated on a l…
Rod-coil copolymers form smectic phases in melts and solutions. A mean-field analysis of nonoverlapping lamellae formed by rod-coil copolymers in a selective solvent of low molecular weight is presented. The system exhibits a first-order, smetic A -smectic C phase transition. The transition is due to competition betwe…
Cross sections for the reactions of Fe+n and Nb+n (n=1–3) with O2 are measured as a function of kinetic energy over a range of 0 to >10 eV. In all systems, analysis yields insight into the kinetics and thermochemistry of the oxidation processes. Nb+n reaction with O2 exothermically near the Langevin–Gioumousis–…
We discuss how concepts from rigidity percolation can be used to understand the low-frequency excitations and elastic properties of network glasses like ${\mathrm{Ge}}_{\mathrm{x}}$${\mathrm{As}}_{\mathrm{y}}$${\mathrm{Se}}_{1\mathrm{\ensuremath{-}}\mathrm{x}\mathrm{\ensuremath{-}}\mathrm{y}}$. When the mean coordinat…
Two stable conformations, a planar or nearly planar rod and a coil, have been located on the potential-energy surfaces of several conducting polymers: polythiophene (PT), poly(3-methylthiophene) (PMeT), polypyrrole (PPy), and poly(3-methylpyrrole) (PMePy). The planar structure is slightly more stable for PT, PPy, and…
Taking into account recent developments and present trends in devices and component technologies, the future development of electrically addressed liquid crystal spatial light modulators is considered. In particular, the combination of single-crystal-silicon active backplane and chiral smectic C liquid crystal technol…
Absorption spectra of ${\mathrm{Tm}}^{3+}$:${\mathrm{Y}}_{3}$${\mathrm{Al}}_{5}$${\mathrm{O}}_{12}$ are reported between 1.9 and 0.26 \ensuremath{\mu}m at 15 and 90 K, and between 0.80 and 0.35 \ensuremath{\mu}m at 1.6 K. Laser-excited emission obtained at 80 K is also reported from the ${\mathrm{Tm}}^{3+}$ manifolds…
Raman scattering experiments from a polycrystalline sample of black phosphorus were done with a diamond-anvil cell from 0.25 to 11.6 GPa at a temperature of 15 K. Three Raman-active modes in the A11 orthorhombic (Cmca) phase were observed as a function of pressure to approximately 7.7 GPa, the point where black phosph…
Molecular dynamics and the embedded-atom method (EAM) have been applied to the study of intergranular hydrogen embrittlement in Ni-based alloys. A new technique was developed for constructing EAM functions from experimental data on binary systems. The technique allows one to express experimental quantities of the bina…
We analyze delayed conduction in three recent models of switching charge-density waves. Each model predicts a power-law dependence of switching delay near threshold: \ensuremath{\tau}\ensuremath{\sim}${\ensuremath{\varepsilon}}^{\mathrm{\ensuremath{-}}\ensuremath{\beta}}$, where \ensuremath{\tau} is the delay and \ens…
The crystallization behavior of evaporated TiO2-SiO2 mixed composition films and its dependence on composition, temperature, time and type of mixing (codeposited or alternating layers) were studied. All codeposited films annealed between 600 and 900 °C with 15%–90% molar TiO2 exhibited crystallization in the anatase p…
Surface-plasmon resonances of silver microparticle aerosols have been measured as a function of average particle size. Resonance line shapes are modeled as a function of particle size and complex refractive index. The surface-plasmon frequency is found to exhibit a red shift from 3.8 to 3.4 eV as the average particle…