Materials Literature
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The crystallization of shear oriented oxyethylene/oxybutylene (E/B) diblock copolymers has been studied by simultaneous small and wide angle x-ray scattering. Crystallization of ordered melts can be accompanied by a change in length scale and retention of the melt orientation. Lamellar melts crystallize with an increa…
We applied ellipsometry to study the distribution of azobenzene fragments in the films of two types of comblike polymers with azobenzene moieties in the side chains before and after ultraviolet (UV) light irradiation. The polymer with an alkyl chain at the end of the azobenzene fragment forms structures with preferred…
The vibrational density of states in the triphenyl phosphite, measured by inelastic neutron scattering, were obtained during isothermal aging at ${T}_{a}=210,$ 213, and 216 K. The low-frequency ${\ensuremath{\omega}}^{n}$ behavior of the vibrational density of states was observed to be time dependent. This is suggesti…
We study the adsorption of polyelectrolytes onto oppositely charged surfaces as the surface charge density is varied while keeping the polyelectrolyte charge density fixed. As observed previously from multilayer adsorption studies, 1,2 nonmonotonic adsorption behavior is obtained in the intermediate surface charge den…
We reconsider the interpretation of x-ray resonant scattering experiments performed on the so-called charge-ordered manganites with Mn 3+ /Mn 4+ = 1. The comparison between these experiments and our x-ray absorption data shows that no real Mn 3+ /Mn 4+ charge ordering occurs in these compounds. However, these experime…
We report a systematic study of manganese perovskites, RE 1- x D x MnO 3 (RE = rare earth; D = Ca, Sr), by means of x-ray absorption near edge structure (XANES) spectroscopy at the Mn K edge. High resolution has been achieved by recording the intensity of the Mn Kβ fluorescence spectrum. All the samples show a unique…
The electron microscopy study of the manganites Bi 1 - x Sr x MnO 3, especially for x = 1 / 2 and x = 2 / 3, has allowed a new type of modulated structure, correlated to charge ordering (CO) phenomena, to be evidenced. The Bi 1 - x Sr x MnO 3 manganites are characterized by a modulated structure, the modulation vector…
The addition of dodecanethiol to a polydisperse platinum colloidal aqueous solution capped with acrylic acid leads to self-assembled monolayers which not only contain various sizes, but also various shapes of nanoparticles. Assembled monolayers arranged in hcp arrays are achieved for mixed shape samples. In the case o…
Several single-molecule magnets with the composition [Mn12O12(O2CR)16(H2O)x] (x = 3 or 4) exhibit two out-of-phase ac magnetic susceptibility signals, one in the 4-7 K region and the other in the 2-3 K region. New Mn12 complexes were prepared and structurally characterized, and the origin of the two magnetization rela…
A drift-diffusion model for spin-charge transport in spin-polarized {\it p-n} junctions is developed and solved numerically for a realistic set of material parameters based on GaAs. It is demonstrated that spin polarization can be injected through the depletion layer by both minority and majority carriers, making all-…
The aim of this paper is to present a streamlined and fully three-dimensional version of the quasicontinuum (QC) theory of Tadmor et al. and to analyze its accuracy and convergence characteristics. Specifically, we assess the effect of the summation rules on accuracy; we determine the rate of convergence of the method…
At first, pressure formulas for the electrons under the external potential produced by fixed nuclei are derived both in the surface integral and volume integral forms concerning an arbitrary volume chosen in the system; the surface integral form is described by a pressure tensor consisting of a sum of the kinetic and…
We have calculated Heisenberg exchange parameters for bcc-Fe, fcc-Co, and fcc-Ni using the scalar-relativistic spin-polarized Green function technique within the tight-binding linear muffin-tin orbital method and by employing the magnetic force theorem to calculate total energy changes associated with a local rotation…
Quasi-low-dimensional (quasi-low-D) inorganic materials are not only ideally suited for angle resolved photoemission spectroscopy (ARPES) but also they offer a rich ground for studying key concepts for the emerging paradigm of non-Fermi liquid (non-FL) physics. In this article, we discuss the ARPES technique applied t…
Electron transport studies for AlGaN/GaN two-dimensional electron gases is presented. Novel defects in the III-V nitrides are treated theoretically for two-dimensional transport. Theory of electron scattering by charged dislocation lines is presented for realistic two-dimensional electron gases. The theory lets us dra…
The one-electron density of states for the half-filled Hubbard model on a triangular lattice is studied as a function of both temperature and Hubbard U using Quantum Monte Carlo. We find three regimes: (1) a strong-coupling Mott-Hubbard regime, characterized by a gap which persists even at high temperatures; (2) a wea…
Addition of butylamine to a solution of colloidal CdSe nanoparticles (NPs) caused a decrease in fluorescence intensity, with no effect on the picosecond bleach recovery of the exciton formation or on the luminescence dynamics. The relative fluorescence quantum yield was found to decrease with increasing butylamine con…
The adsorption of N2 was used to investigate the porosity/morphology of thin films of amorphous solid water. Molecular beams were used to vapor deposit amorphous solid water films on a Pt(111) crystal at a variety of incident growth angles. The amount of N2 adsorbed by the amorphous solid water depends very sensitivel…
The adsorption of several types of alkylamine molecules on individual semiconducting and metallic single-walled carbon nanotubes is investigated by electrical transport measurements. The electrical conductance of semiconducting nanotubes changes drastically upon adsorption of butylamine and 3‘-(aminopropyl)triethoxysi…
In a previous work [ Macromolecules 2000, 33, 8344], nanocomposite materials were obtained using glycerol plasticized starch as the matrix and a colloidal suspension of tunicin an animal cellulose whiskers as the reinforcing phase. The mechanical behavior of resulting films was characterized in both the linear and the…