Materials Literature
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A magnetic sheet made of Fe–Si–Al flakes was found to have excellent permeability and electromagnetic-interferences characteristics in a quasimicrowave band. The flakes prepared by attrition were embedded in a polymer with their planes lying parallel to the sheet plane. This sheet exhibits a peculiar dual dispersion i…
ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTCyclodextrin-Modified Gold Nanospheres. Host−Guest Interactions at Work to Control Colloidal PropertiesJian Liu, Sandra Mendoza, Esteban Román, Matthew J. Lynn, Renliang Xu, and Angel E. KaiferView Author Information Center for Supramolecular Science, Department of Che…
Modified SERS (surface-enhanced Raman scattering) substrates are based on self-assembled monolayers (SAMs) formed from compounds such as alkanethiols. Chain lengths ranging from ethanethiol to octadecanethiol were used to investigate properties of modified SERS substrates. These properties include determining the magn…
We study photoinduced electron transfer from derivatives of poly(p-phenylenevinylene) (PPV) and nanocrystals of cadmium selenide via photoluminescence (PL) quenching and photoinduced absorption (PIA) spectroscopy. Using size-dependent quantum confinement to vary the energy levels of the nanocrystal acceptors, and chem…
A first-order transition above the Curie temperature for ferromagnetic La(FexSi1−x)13 (x=0.86 and 0.88) compounds has been confirmed by applying a magnetic field. The magnetic state changes from the paramagnetic to the ferromagnetic state and the transition field increases with temperature, indicating an itinerant ele…
We report experimental and theoretical investigations on the pressure dependence of the Raman-active radial and tangential vibrational modes of single-wall carbon-nanotube bundles. Using 514.5-nm excitation, we find that the radial mode intensity disappears beyond 1.5 GPa, and the tangential mode intensity also drops…
The existence of the edge states of single-layered H-terminated graphitic ribbons predicted by Nakada et al. [Phys. Rev. B 54, 17 954 (1996)] has been confirmed by first-principles calculations within the framework of the local-density approximation and the pseudopotentials. The edge states in cases of stacked ribbons…
High temperature, solution phase reduction of cobalt chloride in the presence of stabilizing agents was employed to produce magnetic colloids (ferrofluids) of cobalt nanocrystals. We systematically synthesized and isolated nearly monodisperse nanocrystal samples ranging in size from 2 to 11 nm while maintaining better…
A novel layered Rb−Pd polyselenide has been synthesized by methanothermal reaction of Pd 2+ with Se x 2 - (from Se 2 - + Se) in the presence of Rb 2 CO 3 . Rb 2 [Pd(Se 4 ) 2 ]·Se 8 ( I ) reveals a unique structure with infinite [Pd(Se 4 ) 2 ] 2 - sheet polyanions acting as a host for neutral Se 8 rings. The black shin…
Dodecaphenylporphyrins with varying degrees of fluorination of the peripheral phenyl rings (F(x)()DPPs) were synthesized as model compounds for studying electronic effects in nonplanar porphyrins, and detailed electrochemical studies of the chloroiron(III) complexes of these compounds were undertaken. The series of po…
Molecular dynamics simulations of a Xe monolayer sliding on Ag(001) and Ag(111) are carried out in order to ascertain the microscopic origin of friction. For several values of the electronic contribution to the friction of individual Xe atoms, the intra-overlayer phonon dissipation is calculated as a function of the c…
An astonishingly broad application potential in biotechnology, biomimetics, and nanotechnology is revealed by studies on the structure, chemistry, biosynthesis, genetics, self-assembly, and function of supramolecular surface layers (S layers). These are monomolecular, crystalline assemblies of protein or glycoprotein…
Ab initio molecular orbital calculations have been used to study the effect of γ substituents (X = H, F, or CN) on the addition of 1-Y,3-X-disubstituted propyl radicals (Y = F or CN) to ethylene. It is found that, although the γ substituent (i.e. penultimate unit) can exert a significant effect on the stability of the…
Raman and infrared reflection spectra in the backbone deformations and lattice modes range (10−1000 cm -1 ) of EB/ES-I and EB/ES-II polyanilines are discussed and compared with those of an oligomer (BQBBa) and of the constitutive bricks of the polyaniline skeleton: diphenylamine (BB), N, N ‘-diphenyl-1,4-phenylenediam…
The magnetic exchange interactions in copper(II) &mgr;(2)-azido bridged complexes have been studied using several density functionals and both GTO and STO basis sets. From a methodological point of view, we have taken into proper account nonorthogonality effects in the framework of the broken symmetry approach. A rema…
The effects of a step defect and a random array of point defects (such as vacancies or substitutional impurities) on the force of friction acting on a xenon monolayer film as it slides on a silver (111) substrate are studied by molecular dynamic simulations and compared with the results of lowest order perturbation th…
The electronic structure of a single monatomic gold wire is presented for the first time. It has been obtained with state-of-the-art ab-initio full-potential density-functional (DFT) LMTO (linearized muffin-tin orbital) calculations taking into account relativistic effects. For stretched structures in the experimental…
The FT-IR and FT-Raman spectra of three-layered silicates, magadiite, kenyaite, and ilerite have been measured. The correlation between vibrational spectra and the structural properties of silicates under investigation has been made. The unit cells of all three silicates appear to be centrosymmetric since the mutual e…
A novel procedure has been developed for the synthesis of spongelike silica membranes with three-dimensional meso−macrostructures. The process utilizes multiphase media comprised of a mesoscopically ordered block copolymer/silica phase that macroscopically separates from an electrolyte phase. This results in hierarchi…
Increased interest in molecular time scales below the glass transition temperature, T g, has arisen from the desire to identify the conditions (e.g., temperature) where the molecular processes which lead to unwanted changes in amorphous systems (e.g., chemical reactivity, crystallization, structural collapse) are impr…