Materials Literature
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We report the observation of the influence of light polarization on the photocrystallization process and on the properties of crystallized films. Irradiation with linearly polarized He–Ne laser light results in the preparation of polycrystalline films with strong optical anisotropy (dichroism), the sign of which is de…
The deposition of thin alternating layers of Cu and Nb on Si(100) substrates has been studied by transmission electron microscopy as a function of layer thickness. For layer thickness above 25 Å, there is a strong texture orientation relationship with the close packed planes of fcc Cu parallel to close packed planes o…
Solid films of matrix-free, closely packed CdSe nanocrystals have been prepared and surface stabilized. An efficient suppression of nonradiative recombination channels is achieved. The absolute quantum efficiency has been determined spectrally resolved using an integrating sphere, and values between 1% and 10% are obt…
Muon spin relaxation has been used to probe the highly anisotropic motion of polaronic charge carriers in the emeraldine base form of polyaniline. The measured diffusion rate along the polymer chain for negative polarons shows a metalliclike temperature dependence, which is saturated at low temperatures but becomes li…
The pressure of the hard-sphere fluid was measured from near the equilibrium freezing density to the maximum density where the properties of the metastable fluid can be measured without it freezing or becoming glassy. Above the freezing density the measured pressures increase faster than the predictions of Padé approx…
Medieval and early Renaissance ... instruments were normally played in consorts or choruses of their own kind, in various pitches, the bass often being supplied by an instrument of a different character because of difficulty in constructing an effective instrument of the group in a sufficiently low pitch. This remaine…
We have used an optical pump-and-probe technique to measure the temperature dependence of the thermal conductivity, κ(T), of isotopically pure Si. The sample was made from 99.7% Si28 by liquid phase epitaxy. Measurements were performed over the temperature range of 100–375 K. We found an increase in the thermal conduc…
Tree models for rigidity percolation are introduced and solved. A probability vector describes the propagation of rigidity outward from a rigid border. All components of this ``vector order parameter'' are singular at the same rigidity threshold, $p_c$. The infinite-cluster probability $P_{\infty}$ is usually first-or…
Ring torsion effects on optical excitation properties in poly(para-phenylene) (PPP) and polyaniline (PAN) are investigated by the intermediate exciton formalism. Long-range excitons are characterized, and the long-range component of the oscillator strengths is calculated. We find that ring torsions affect the long-ran…
We present the results of a molecular dynamics computer simulation study in which we investigate whether a supercooled Lennard-Jones liquid exhibits dynamical heterogeneities. We evaluate the non-Gaussian parameter for the self part of the van Hove correlation function and use it to identify ``mobile'' particles. We f…
It is shown that the VLEED, furnished with appropriate modelling approaches, is able to reveal comprehensive information about the details of a surface. Constructing Brillouin zones from the critical positions on the angular-resolved VLEED spectra yields information about valence bands and in-plane reconstruction of t…
The grafting polymerization of methyl methacrylate (MMA) and cellulose from henequen (Agave fourcroydes) is investigated as a function of the initiator concentration (cerium-and-ammonium nitrate) and the monomer/cellulose ratio. The formation of cellulose-g-PMMA is confirmed by IR spectroscopy, DSC, and TGA. Both the…
Novel acylation reactions of cellulose were accomplished with a series of unsaturated carboxylic acids or their respective anhydrides including crotonic acid (CRA), methacrylic acid (MAA), vinyl acetic acid (VAA), fumaric acid monoethyl ester (FAME), and cinnamic acid (CINA) in lithium chloride (LiCl)/dimethylacetamid…
In the present study, a conductive polyaniline-dodecyl benzene sulfonic acid (PANI-DBSA) complex, prepared by a thermal doping process, and its blends with thermoplastic polymers, prepared by melt processing, were investigated. PANI-DBSA characterization included conductivity measurements, morphology, crystallography,…
Macroscopic orientational ordering of the pores of condensed hexagonal mesostructured silica (MCM-41) was achieved through alignment of an unpolymerized, hexagonal, lyotropic silicate-surfactant liquid crystal in a high magnetic field. This alignment was preserved after polymerization of the silicate species by acid t…
We analyze BEEM experiments. At low temperatures and low voltages, near the threshold value of the Schottky barrier, the BEEM current is dominated by the elastic component. Elastic scattering by the lattice results in the formation of focused beams and narrow lines in real space. To obtain the current injected in the…
In this paper, we have considered the mechanical stability of a jellium system in the presence of spin degrees of freedom and have generalized the stabilized jellium model, introduced by J. P. Perdew, H. Q. Tran, and E. D. Smith [Phys. Rev. B42, 11627 (1990)], to a spin-polarized case. By applying this generalization…
Molecular-dynamics simulations of KNbO$_3$ reveal preformed dynamic chain-like structures, present even in the paraelectric phase, that are related to the softening of phonon branches over large regions of the Brillouin zone. The phase sequence of ferroelectric transitions is correctly reproduced, showing that the fir…
Steady-state and time-resolved luminescence spectroscopy of atomic zinc isolated in thin film samples of the solid rare gases, prepared by the cocondensation of zinc vapor with argon, krypton, and xenon has been recorded at 6.3 K using synchrotron radiation. Pairs of emission bands result from photoexcitation of the s…
Dielectric spectroscopy has been employed to study selectively the local and global dynamics of polyisoprene (PI) in three microphase separated star diblock copolymers (SI)4, where PI and polystyrene (PS) form the core and corona, respectively. The thermally induced order-to-disorder transition (ODT) has been identifi…