Materials Literature
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Abstract We have been investigating the synthesis of quantum dots of CdSe, CuInS 2 , and CuInSe 2 for use in an intermediate bandgap solar cell. We have prepared a variety of quantum dots, using the typical organometallic synthesis routes pioneered by Bawendi et al. in the early 1990s. However, unlike previous work in…
We develop a general theory of electron--hole recombination in organic light emitting diodes that leads to formation of emissive singlet excitons and nonemissive triplet excitons. We briefly review other existing theories and show how our approach is substantively different from these theories. Using an exact time-dep…
The effect that an additional energy barrier E_{kr} for step adatoms moving around kinks has on equilibrium step edge fluctuations is explored using scaling arguments and kinetic Monte Carlo simulations. When mass transport is through step edge diffusion, the time correlation function of the step fluctuations behaves…
The Hall resistivity, magnetoresistance, and magnetization of La_{1-x}Ca_{x}CoO_{3} epitaxial films with x between 0.25 and 0.4 grown on lanthanum aluminate were measured in fields up to 7 T. The x=1/3 film, shows a reentrant metal insulator transition. Below 100 K, the x=1/3 and 0.4 films have significant coercivity…
Human malaria, one of the most striking, reemerging infectious diseases, is caused by several types of Plasmodium parasites. As the parasite digests hemoglobin in human red blood cells, the heme byproduct crystallizes into micron-sized malaria-pigment (hemozoin). Making use of a recently reported powder-crystal struct…
We present an experimental and theoretical study of the conduction states of crystalline Si films confined within amorphous SiO_2 barriers, using the Si-2p core-level excitations. The spectral peaks near the conduction band minimum are compared with the bulk silicon spectrum. In the Si quantum wells, it is found that…
Performing light scattering experiments we show that introducing short-ranged attraction to a colloid suspension of nearly hard spheres by addition of a free polymer produces new glass-transition phenomena. We observe a dramatic acceleration of the density fluctuations amounting to the melting of a colloidal glass. Up…
The science of surface and colloid chemistry has been expanding at a rapid pace, resulting in new areas of development, additional applications, and more theoretical and experimental information on related systems. Completely revised and expanded to reflect the very active worldwide research on this subject, this is t…
Temperature-dependent measurements of luminescent intensity and lifetimes of the ${4f}^{2}{[}^{1}{\stackrel{\ensuremath{\rightarrow}}{{S}_{0}}}^{1}{I}_{6}]$ and ${4f}^{1}{5d}^{1}\ensuremath{\rightarrow}{4f}^{2}$ emission for ${\mathrm{BaSO}}_{4}:{\mathrm{Pr}}^{3+}$ were performed. It was found that the intensity of th…
We investigate the electromagnetic mechanism in surfaceenhanced Raman scattering (SERS) from randomly rough metal surfaces with Gaussian statistics and Gaussian correlation function. By means of rigorous numerical calculations, large average SERS enhancement factors (above 104) are encountered when the correlation len…
Highly ordered organic–inorganic nanocomposite arrays formed by filling anodized aluminum oxide nanopores (50 nm size) with Rhodamine 123 (Rh123) dye has been studied by visible absorptive, fluorescent spectroscopy, and atomic force/scanning electron microscopy techniques in this work. The absorbance and fluorescence…
A simple thermal treatment has been used to produce a variety of elongated single crystalline magnesium oxide nanostructures. Incipient evaporation of a magnesium diboride starting powder combined with a mixed oxygen/argon process gas provided the constituents for nanostructure growth. Electron diffraction and energy…
Abstract Adhesion of dense linear polymer chains containing a small number of randomly distributed sticker groups (ϕ X ) to a solid substrate containing receptor groups (ϕ Y ) has been analyzed by a single‐chain scaling approach. An entanglement sink probability (ESP) model motivated by vector percolation explains the…
Composite thin films of (La0.7Sr0.3MnO3)1−x:(MgO)x (x=0–0.5) were grown on Al2O3 (0001) substrates by a metalorganic aerosol deposition technique. A columnar growth of the films with the predominance of (111)- and (1̄10)-orientation was observed. Pure films (x=0) show a Curie temperature of TC=362 K, a metallic behavi…
Molecular dynamics (MD) simulations of lithium metasilicate $({\mathrm{Li}}_{2}{\mathrm{SiO}}_{3})$ in the glassy and supercooled liquid states have been performed to illustrate the decay with time of the cages that confine individual ${\mathrm{Li}}^{+}$ ions before they hop out to diffuse cooperatively with each othe…
Abstract A set of well‐defined poly(ethylene‐ alt ‐propylene)‐ b ‐polylactide (PEP‐PLA) diblock copolymers containing volume fractions of PLA ( f PLA ) ranging between 0.08 and 0.91 were synthesized by a combination of living anionic polymerization, catalytic hydrogenation, and controlled coordination‐insertion ring‐o…
We have measured the site-specific valence electronic structure of $\ensuremath{\alpha}\ensuremath{-}{\mathrm{Fe}}_{2}{\mathrm{O}}_{3}$ by using a spatially modulated x-ray standing wave as the excitation source for photoemission. Contributions to the valence-band density of states from oxygen and iron ions are separa…
The loss factor (tan δ) of ferroelectric material at microwaves and the tunability (n) defined as a ratio of the dielectric permittivity at zero dc field to the dielectric permittivity at the given field are strongly connected with the softness of so-called ferroelectric soft mode. The loss factor and the tunability a…
a- and b-axis-oriented epitaxial Bi4Ti3O12 films were prepared on (101)TiO2 (rutile) substrates at 630 °C by metalorganic chemical vapor deposition and their perfect epitaxial growths were confirmed by several x-ray diffraction measurements. As the bottom electrode, (101)-oriented conductive materials with the same ru…
The Heusler alloys are a group of magnetic materials that will form essential components in hybrid, ferromagnet–semiconductor devices that utilize spin injection. We demonstrate that such an alloy, Co2MnGa:GaAs(001) is ferromagnetic at 300 K and has controllable magnetic properties. A weak in-plane uniaxial anisotropy…