Materials Literature
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The isothermal crystallization of in-situ-polymerized and melt-processed nylon-6/montmorillonite nanocomposites was studied by simultaneous small- and wide-angle X-ray scattering using synchrotron radiation. The isothermal crystallization rates, in the nucleation-controlled regime, for the nanocomposites are significa…
Recent progress in developing highly efficient nonlinear optical dendrimers and polymers for high-performance electro-optic (EO) devices has been reviewed. Our efforts are focused on using nanoscale architectural control to tailor the size, shape, conformation, and functionality of NLO chromophores and macromolecules…
A translationally invariant formulation of the Hartree-Fock (HF) $Γ$-point approximation is presented. This formulation is achieved through introduction of the Minimum Image Convention (MIC) at the level of primitive two-electron integrals, and implemented in a periodic version of the ONX algorithm [J. Chem. Phys, {\b…
An instrument has been constructed to measure a large range of magnetostriction and thermal expansion between room temperature and 4 K in a superconductive split-coil magnet, that allows investigation in magnetic fields up to 12 T. The very small bulk samples (up to 1 mm in size) as well as big ones (up to 13 mm) of t…
The barrier formation for metal/organic semiconductor interfaces is analyzed within the Induced Density of Interface States (IDIS) model. Using weak chemisorption theory, we calculate the induced density of states in the organic energy gap and show that it is high enough to control the barrier formation. We calculate…
We use the local-density approximation (LDA) and $\mathrm{LDA}+U$ schemes to study the magnetism of (GaMn)As and (GaMn)N for a number of Mn concentrations and varying number of holes. We show that for both systems and both calculational schemes the presence of holes is crucial for establishing ferromagnetism. For both…
A detailed analysis of the strong room-temperature photoluminescence (PL) signal of size controlled nc-Si is reported. The size control of nc-Si is realized by evaporation of ${\mathrm{S}\mathrm{i}\mathrm{O}/\mathrm{S}\mathrm{i}\mathrm{O}}_{2}$ superlattices and subsequent thermally induced phase separation. By this m…
A new Al potential with improved stacking fault energy is constructed using the force-matching method. The potential is fitted to an ab initio forces database and various experimental data. By using a slightly larger cut-off, we found that the new potential gives the relaxed stacking fault energy in the experimental r…
The formation of a metal/PTCDA (3, 4, 9, 10-perylenetetracarboxylic dianhydride) interface barrier is analyzed using weak-chemisorption theory. The electronic structure of the uncoupled PTCDA molecule and of the metal surface is calculated. Then, the induced density of interface states is obtained as a function of the…
We calculate an effect of spinless impurities on the spin Hall effect of the Luttinger model representing p-type semiconductors. The self-energy in the Born approximation becomes diagonal in the helicity basis and its value is independent of the wavenumber or helicity. The vertex correction in the ladder approximation…
Following our previous work [S. Murakami, N. Nagaosa, S. C. Zhang, Science 301, 1348 (2003)] on the dissipationless quantum spin current, we present an exact quantum mechanical calculation of this novel effect based on the linear response theory and the Kubo formula. We show that it is possibxle to define an exactly c…
A tunable-focus spherical lens using two flat substrates and inhomogeneous electric field over a homogeneous liquid crystal (LC) layer is demonstrated. The top flat substrate has an imbedded spherical indium–tin–oxide (ITO) electrode and the bottom has a planar ITO electrode on its inner surface. The inhomogeneous ele…
Abstract Summary: A rather simple but yet effective way to achieve a superhydrophobic film by extending a Teflon film is proposed. The water‐contact angle can be increased from 118 to 165° by extending to ca. 190%. The fibrous crystals and the increasing distance between the fibrous crystals are believed responsible f…
Frequency upconverted emissions centered at 526 and 547 nm from two thermodynamically coupled excited states of Er3+ doped in BaTiO3 nanocrystals were recorded in the temperature range from 322 to 466 K using a diode laser emitting at 980 nm as the excitation source. The ensemble measurements of the fluorescence inten…
Two-dimensional carbon nanostructures (carbon nanowalls) were fabricated using capacitively coupled radio-frequency plasma-enhanced chemical vapor deposition assisted by H radical injection. Carbon nanowalls were grown on Si, SiO2, and sapphire substrates without catalyst, and independent of substrate materials. Corre…
We theoretically show that the thermal conductance associated with electron–phonon coupling in a metal near a metal–nonmetal interface can be estimated as hep=Gkp, where G is the volumetric electron–phonon coupling constant and kp is the phonon or lattice thermal conductivity of the metal. The expression suggests hep≈…
Using electrodynamics calculations, we have discovered one dimensional array structures built from spherical silver nanoparticles that produce remarkably narrow ( approximately meV or less) plasmon resonance spectra upon irradiation with light that is polarized perpendicular to the array axis. The narrow lines require…
Optical emission studies were performed to investigate thermal and dynamical properties of a plume produced by laser ablation of a graphite target in a nitrogen atmosphere. Experimental spectra of <TEX>$C_2(d^3{\Pi}_g{\to}a^3{\Pi}_u$</TEX>, <TEX>${\Delta}_V$</TEX>=1) and CN (<TEX>$B^2{\Sigma}^+{\to}X^2{\Sigma}^+,{\Del…
Abstract The morphology and the thermal behavior of nascent polyethylene (PE) polymerized on flat models for the Phillips CrO x /SiO 2 catalyst were investigated using low‐voltage scanning electron microscopy (LVSEM) and differential scanning calorimetry (DSC). Ethylene polymerizations were performed at 25 °C and 70 °…
Abstract A novel ABB′ monomer, an isomeric mixture of 4‐[4‐(2,4‐diaminophenoxy)phenoxy]phthalic acid 2‐methyl ester, was successfully prepared. The direct polycondensation of the ABB′ monomer was carried out to form polyamic acid monomethyl ester as a precursor with an inherent viscosity of 0.30 dL/g and a number‐aver…