Materials Literature
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We have carried out NPT molecular dynamics simulations of isolated ellipsoids in a glass forming binary mixture to gain insight into the nature of orientational relaxation (OR) in a viscous liquid. At high pressures when the liquid is highly viscous, the OR is found to occur mainly via correlated hopping, sometimes in…
In the framework of the two-step model of Auger decay the orientation of the krypton ${3d}^{\ensuremath{-}1}$ and xenon ${4d}^{\ensuremath{-}1}$ primary hole states has been determined as a function of photon energy. This was achieved by carrying out spin-polarization measurements of the Kr ${M}_{4,5}{N}_{2,3}{N}_{2,3…
We have studied the electrical conductivity of well–aligned samples of hexahexylthiotriphenylene (HHTT) and hexapentyloxyanthraquinone (HPA) in the pure, as well as doped, states. The former compound was doped with 0.62 mol % by weight of the electron acceptor, trinitrofluorenone (TNF), the latter with 0.60 mol % by w…
The magnetic properties of the molecular cluster ${\mathrm{Mn}}_{12}\mathrm{Ac}$ are due to the four ${\mathrm{Mn}}^{3+}$ ions that have spins $S=3/2$ and the eight ${\mathrm{Mn}}^{4+}$ ions with spins $S=2.$ These spins are coupled by an exchange mechanism. We determine the four exchange couplings assuming a Heisenbe…
A novel soluble aryl amide-bridged ladderlike polymethylsiloxane (A-LPMS) was synthesized by stepwise coupling polymerization on the basis of amido H-bonding self-assembling template from monomer N,N'-bis(3-methyldiethoxylsilylpropyl)-[4,4'-oxybis(benzyl amide)]. The monomer was prepared in a high yield by the hydrosi…
The mechanism for isotopic exchange by proton hopping and subsequent reorientation of H2O molecules in vapor-deposited, 0.1 mol % 2-naphthol containing amorphous solid water [M. Fischer and J. P. Devlin, J. Phys. Chem. 99, 11584 (1995)] has been reconsidered and an alternative mechanism in terms of diffusion controlle…
A new mechanism of electron paramagnetic resonance in spherical zinc-blende semiconductor nanocrystals, based on the extended orbital motion of electrons in the entire nanocrystal, is presented. Quantum confinement plays a crucial role in making the resonance signal observable. The mechanism remains operative in nanoc…
A Zr-promoted Pd/HZSM-5 catalyst, prepared by an impregnation method, was found to possess high catalytic activity as well as thermal and hydrothermal stability for low-temperature methane combustion.
Thin films of poly(styrene-b-methyl methacrylate) diblock copolymers above the bulk order-disorder transition temperature, within a certain thickness range, are structurally unstable on SiO(x)/Si substrates. They dewet autophobically, forming droplets on a self-assembled brush. We investigated the late-stage evolution…
This contribution reports the first synthesis of conducting polymers (CPs), specifically, polyaniline (PAn) and polypyrrole (PPy), in supercritical carbon dioxide (scCO2). CPs synthesized electrochemically in scCO2 were characterized with cyclic voltammetry (CV), four-point probe conductivity, scanning electron micros…
We present a theoretical study of a new class of polymer materials of much recent experimental interest: polymer networks bearing dendritic wedges in the middle of long network strands. We focus on the Rouse dynamics of such cross-linked polymers and perform our study in three steps, considering first single dendritic…
Two analytical procedures based on the time-dependent Hartree–Fock (TDHF) scheme are elaborated to evaluate the first derivatives of the dynamic first hyperpolarizability with respect to atomic Cartesian coordinates. In the first scheme, the mixed third-order TDHF equations are solved iteratively to obtain the third d…
This work presents the synthesis and characterization of SiO 2:metal (Ni, Co, Ag, and Fe) nanocomposites processed by the polymerizable complex method. The polymeric precursor solutions obtained were characterized by means of FT-Raman and 13 C NMR spectroscopy. The results show the formation of a hybrid polymer with c…
We report on a Monte Carlo study of the liquid crystal phases of two model fluids of linear elongated molecules: (a) hard spherocylinders with an attractive square-well (SWSC) and (b) purely repulsive soft spherocylinders (SRS), in both cases for a length-to-breadth ratio L*=5. Monte Carlo simulations in the isotherma…
The adsorption of thiolate radicals on the Au24 nanocluster truncated from the Au (111) surface is investigated using first principles electronic structure calculations under the density functional theory formalism. Particular emphasis is given to understanding the chemical interactions at the gold-sulfur interface. I…
Spectroscopic methods combined with density functional calculations are used to develop a detailed bonding description of the mu(4)-sulfide bridged tetranuclear Cu(Z) cluster in N(2)O reductase. The ground state of Cu(Z) has the 1Cu(II)/3Cu(I) configuration. The single electron hole dominantly resides on one Cu atom (…
The photoluminescence (PL) properties of several recently synthesized ligand-stabilized polynuclear gold(I) selenide complexes were investigated. [Au 18 Se 8 (dppe) 6 ]Br 2 {dppe = bis(diphenylphosphanyl) ethane} ( I ) is distinguished by the bright-red long-lived PL (phosphorescence) in the solid state, photosensitiz…
Catalytic formation of N2O and NO2 were studied employing density functional theory with generalized gradient approximations, in order to investigate the microscopic reaction pathways of these catalytic processes on a Pt(111) surface. Transition states and reaction barriers for the addition of chemisorbed N or chemiso…
The electronic properties of Mg-O divacancy defects at the MgO surface obtained by removing of a pair of O and Mg ions from terrace, step, or corner sites have been investigated using an embedded cluster model. Long-range polarization and lattice relaxation effects have been included through a shell model approach. It…
The mechanism for the failure of brittle materials during uniaxial compressive shockloading has been the subject of much discussion. In particular, the physical interpretation of the yield point, the Hugoniot elastic limit, remains poorly understood. It is additionally hypothesized that different materials display dif…