Materials Literature
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We present a theoretical study of the role of the local environment in the electronic properties of carbon nanotubes: isolated single- and multi-wall nanotubes, nanotube-ropes, tubes supported on gold and cutted to finite length. Interaction with the substrate or with other tubes does not alter the scanning-tunneling-…
We show that the current carrier density collapse in doped manganites, which results from bipolaron formation in the paramagnetic phase, leads to a colossal change of the optical conductivity in an external magnetic field at temperatures close to the ferromagnetic transition. As with the colossal magnetoresistance (CM…
In this paper we measure the optical extinction spectrum of a periodic array of silver nanoparticles fabricated by nanosphere lithography (NSL) and present detailed comparisons of the results with predictions of electrodynamic theory. The silver nanoparticles are small (∼100 nm) compared to the wavelength of light but…
The transport and relaxation dynamics of singlet excitons of rodlike [tetramethoxytetrakis(octyloxy)phthalocyaninato]polysiloxane (PcPSi) in tetrahydrofuran solution were investigated on the femtosecond scale by transient absorption spectroscopy. Singlet excitons are generated upon excitation into the ground-state abs…
Reaction of the tripodal ligands tris(N-alkylbenzimidazol-2-ylmethyl)amine with europium perchlorate affords the luminescent complexes [Eu(Rntb)2](ClO4)3·nCH3CN·0.5H2O (R = methyl, npropyl; n = 1, 2) in which the central Eu3+ ion is well encapsulated in a cubic coordination environment. Right- or left-handed screw arr…
Graphite nanofibers are a newly developed type of material produced by the catalytic decomposition of carbon containing gases at high temperatures. The individual components of these conformations, small-sized graphite crystallites, are arranged in such a manner that only the edge regions are exposed. The carbon atoms…
Liquid crystals based upon bent-rod mesogens are of interest for the design of novel polar and/or biaxial phases. This study reports bent-rod mesogens containing a variable lateral dipole moment and the stability of their phases. X-ray crystallography suggests that the bent-rod and lateral dipoles produce antiparallel…
The adsorption of CO on Au thin film electrodes vacuum-deposited on silicon substrate has been studied in 0.1 M perchloric acid solution by surface-enhanced infrared absorption spectroscopy (SEIRAS) with the Kretschmann attenuated-total-reflection configuration. Scanning tunneling microscopy (STM) was used to investig…
Approximating the shape of the measured in $Bi_2Sr_2CaCu_2O_y$ magneto-thermopower (TEP) $ΔS(T,H)$ by asymmetric linear triangle of the form $ΔS(T,H)\simeq S_p(H)\pm B^{\pm}(H)(T_c-T)$ with positive $B ^{-}(H)$ and $B ^{+}(H)$ defined below and above $T_c$, we observe that $B ^{+}(H)\simeq 2B ^{-}(H)$. In order to acc…
Local density functional results are presented for the electron-doped metallochloronitrides A(x)ZrNCl and A(x)HfNCl, A = Li or Na, which superconduct up to 25K. The alkali non-stoichiometry is treated in a virtual crystal approximation. The electronic structure is strongly two dimensional, especially in the conduction…
We comment on a recent article by H. L. Neal [Am. J. Phys. 66, 512 (1998)], in which an analytic expression for the Hohenberg-Kohn functional was derived for one-dimensional two-particle systems with the harmonic interaction. We argue that the functional given by Neal is not exact but really constitutes an approximati…
ADVERTISEMENT RETURN TO ISSUEPREVNoteNEXTThree-Step Synthesis and Absorption and Emission Properties of Peripherally Peralkynylated TetrapyrazinoporphyrazinesRüdiger Faust and Christian WeberView Author Information Christopher Ingold Laboratories, Department of Chemistry, University College London, 20 Gordon Street, L…
A quantitative structure−property relationship (QSPR) investigation was performed to develop a mathematical link between molecular structure and the clearing temperature of a series of structurally related liquid crystals. Molecular structures were encoded by a series of numerical descriptors encoding information rega…
A new ordered oxygen-deficient perovskite, LaBaMn 2 O 5.5, has been synthesized, using the topotactic deoxygenation of the ordered LaBaMn 2 O 6 perovskite. The crystal structure of this manganite was solved in the space group Ammm ( a = 3.86 Å, b = 8.19 Å, c = 15.47 Å) from neutron powder diffraction data. The [Mn 2 O…
We present Monte Carlo simulations for the size and temperature dependence of the diffusion coefficient of adatom islands on the Cu(100) surface. We show that the scaling exponent for the size dependence is not a constant but a decreasing function of the island size and approaches unity for very large islands. This is…
We study the effect on CPP GMR of changing the order of the layers in a multilayer. Using a tight-binding simple cubic two band model (s-d), magneto-transport properties are calculated in the zero-temperature, zero-bias limit, within the Landauer-Buttiker formalism. We demonstrate that for layers of different thicknes…
Selection of candidate materials and processes for manufacturing structural members is of great moment in designing surface micromechanics devices. The known arts of obtaining superficial microstructures, as a rule, with the use of a 'sacrificial' layer were based on the employment of polysilicon as a working material…
Several aspects of the heterogeneous actions of aqueous and gaseous HCl on the chemical behavior of 3,4-epoxycyclopentanone (=6-oxabicyclo[3.1.0]hexan-3-one; 1) included in the asymmetric cages of tri-o-thymotide (TOT) clathrates belonging to space groups P3121 are described, showing specific features strikingly at va…
Manganese–molybdenum–diethyldithiocarbamate [MnMoO2(Et2dtc)4(H2O)] {Et2dtc=diethyldithiocarbamate} complex has exhibited reversible photogalvanic behaviour in aqueous dimethylformamide medium when studied in a Honda cell. The photogalvanic behaviour has been further investigated by varying the pH, temperature and phot…
The phase separation kinetics of ultrathin deuterated poly(styrene)/poly(butadiene) polymer blend films spun cast onto striped self-assembled monolayer (SAM) substrates is studied by atomic force microscopy (AFM). Fourier transform analysis of the AFM topographic data at various stages of the film pattern development…