Materials Literature
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Explicit solutions for the Brazovskii-Kirova continuum model of cis-polyacetylene are presented for the following three configurations: two polarons, two bipolarons, and a polaron and a bipolaron coexisting on a single chain. The results show that two polarons attract each other with a long-range potential reflecting…
A relatively simple technique has been developed to calibrate particle- and droplet-sizing instruments manufactured by Malvern and other similar Fraunhofer diffraction particle-sizing instruments. Measurements of standard reticles using an instrument calibrated in this manner demonstrate the effectiveness of the proce…
In light of new experimental observations, a mechanism for the photogeneration of charge carriers in trans-polyacetylene is presented. By way of introduction, we discuss the qualitative changes in the picture of charged-solition photogeneration that are expected due to the inclusion of electron correlation effects. In…
Above a few hundred eV kinetic energy, Auger electrons and photoelectrons exhibit strong forward scattering by overlying atoms, and this produces intensity peaks at polar and azimuthal angles corresponding to internuclear axes. This provides a new structural probe which is especially useful for studying epitaxy, surfa…
High resolution core level photoemission spectroscopy has been used to obtain the first direct identification of the chemical species remaining on silicon surfaces after exposure to fluorine. Both Si(111) 2×1 and Si(111) 7×7 were exposed to fluorine via the dissociative chemisorption of XeF2. For fluorine coverages in…
We discuss two mechanisms proposed to explain dc switching of a bistable liquid-crystal boundary layer display. These are (1) biasing by double layer fields that arise from charge of one sign preferentially adsorbed at the walls, and (2) asymmetry in the transient depletion layer fields which result from a difference…
A theory of relaxation (the time-dependent change of macroscopic properties) of nonpolymeric viscous liquids and glasses is presented. The fluid is described by a set of quasiequilibrium structures, and a master equation gives the transitions among these structures. Any structural change is presumed to require a coope…
Detailed and fully consistent calculations of absorption and resonant Raman scattering spectra from trans-${(\mathrm{CH})}_{x}$ have been performed by using a bimodal Gaussian distribution centered on short and long segments which form the trans-${(\mathrm{CH})}_{x}$ chain. Such results are in good agreement with the…
The electrical resistivity of metallic thin films due to the scattering of conduction electrons with rough surfaces and with a random distribution of static impurities within the film is calculated here quantum mechanically using Mori's formalism. The detailed profiles of the surfaces enter into our theory through the…
We have employed the techniques of photoelectron spectroscopy (with tunable synchrotron radiation $30\ensuremath{\le}h\ensuremath{\nu}\ensuremath{\le}100$ eV) and inverse photoemission spectroscopy at $h\ensuremath{\nu}=9.7$ eV to study respectively the occupied and unoccupied electronic states of $n$-type ${\mathrm{S…
Electroluminescence from metal-insulator-semiconductor structures with silicon dioxide (SiO2) layers containing varying amounts of excess silicon (Si) in the form of tiny Si precipitates have been studied in detail. Bulk insulator emission from the Si islands is shown to dominate over emission from either the SiO2 mat…
Scatterings of near-zone-boundary phonons by isotopic disorder in diatomic GaAs InSb crystals are studied theoretically. In multiatomic lattices the scattering rate depends importantly on the vibrational amplitudes of constituent atoms. We find that the wave-vector dependences of these amplitudes, which are predicted…
We present a new method of electrochemical polymerization of poly(thiophene) using dithiophene as the starting material, from which we obtain a high-quality film with a sharp interband absorption edge. An in situ study of the absorption spectrum during the electrochemical doping process has been carried out. In the di…
Photoemission, optical-absorption, and isochromat spectra of NiO and ${\mathrm{NiCl}}_{2}$ are studied theoretically by the consideration of configuration interactions within the metal-ligand cluster. It is shown that the satellites in the valence-band photoemission spectra contain significant ${d}^{7}$ final-state co…
We present the results of tight-binding band-structure calculations on a deformable polypyrrole chain, as a function of doping. The states which are produced are polarons and bipolarons whose excitation spectrum explains the optical-absorption data.
Three structural models of amorphous carbon with differing percentages of threefold- and fourfold-coordinated atoms were constructed and analyzed, along with a purely four-coordinated amorphous Ge model which was scaled to diamond bond lengths. The radial distribution function and interference function, $F(k)$, of the…
A capstan method is used to measure the fibre-fibre and fibre-metal coefficients of friction of single polyester staple fibres. Tests have been conducted over a range of relative speeds (0.03-290 m min -1 ), normal loads (0.3-16 mN), and against two stainless steel pins of surface roughness 0.11 and 0.28 mu m RA. The…
The preparation of suitably large protein single crystals is essentially the rate-determining step of protein x-ray structure determinations. Attempts to produce single crystals with two model compounds-beta-galactosidase and lysozyme-under conditions of microgravity were successful. Crystals formed by salting out fro…
Thermally induced surface-driven convection (thermal Marangoni convection) was investigated in the Spacelab 1 microgravity environment. The configuration studied is related to the floating-zone technique used for crystal growth.
The majority- and minority-spin states of the exchange-split virtual bound state of Mn impurities in Cu and Ag are studied with high-resolution photoemission and bremsstrahlung isochromat spectroscopy. The exchange splitting is found to be close to the atomic value. The majority-spin state is strongly hybridized with…