Materials Literature
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Surface and structural properties of commercially available Carbopack graphitized carbon blacks with specific surface areas from 6 to 225 m 2 /g were studied using nitrogen adsorption in a wide range of pressures. Specific surface areas, total pore volumes, and pore size distributions were evaluated. It was observed t…
Organized polymeric assemblies that incorporate bioactive sequences and structures are finding important applications for the study of protein structure-function relationships. We have recently described a heteropolymeric peptide-amphiphile system that forms organized structures in solution and on surfaces. While the…
<div class="htmlview paragraph">Catalytic performance can be improved by reducing heat capacity and increasing geometric surface area (GSA). The effects of the catalyst layout and the substrate cell structure were investigated on the catalytic performance. The catalyst layout covers an under-floor catalyst only,…
Configurational and Conformational Isomeric Paratopic, Rotational Dynamics Tetraepoxy[30]annulenes(6.2.6.2) and Diatropic Tetraoxa[30]porphyrin(6.2.6.2) Dications: Detection of a Tetraepoxy[31]annulene(6.2.6.2)Radical Cation The synthesis of tetraepoxy[32]annulenes(6.2.6.2) (4) by a cyclizing twofold Wittig reaction o…
Polyamidoamine dendrimers have been surface-modified via peptide coupling with pyridyl, bipyridyl, and terpyridyl ligands to give the analogous polypyridyl dendrimer ligands in high yield. Complexation of the pendant chelating groups with appropriate ruthenium(II) precursor complexes yielded dendrimers surface-functio…
Single crystals of benzamide which form hydrogen-bonded (001) bilayers are obtained from ethanol or 1-propanol solutions. The added presence of amide cosolvent such as X-CONH 2, X = CH 3 or CF 3, yields very thin (001) plates which are twinned. Grazing incidence X-ray diffraction (GIXD) measurements from the (001) sur…
Self-assembled multilayer thin films of nanometer-sized gold particles linked with organic dithiols have been prepared on glass, indium tin oxide, and gold substrates. The gold particles within these structures retain their integrity and no sintering occurs as demonstrated by their optical absorbance, ellipsometry, an…
Six-coordinated Fe(II) complex ions [FeL 3 ] 2+ (L = en, amp, bpy, dmbpy, phen, and dmphen), prepared in a supercage of zeolite Y, were characterized by UV−vis, XRD, Mössbauer spectroscopy, and IR. The UV−vis spectra and XRD patterns of the zeolite encapsulating the Fe(II) complex ions show that [Fe(en) 3 ] 2+, [Fe(am…
The interaction of isolated Cu, Pd, and Cs atoms on regular and defect sites of the SiO 2 surface has been studied with cluster models. Hartree−Fock, density functional theory, and multireference configuration interaction methods have been used to characterize the bonding of the metal atoms at the following sites: bri…
Directional solidification of lamellar eutectic structures submitted to uniaxial stress is investigated. In the spirit of an approximation first used by Jackson and Hunt, we calculate the stress tensor for a two-dimensional crystal with triangular surface, using a Fourier expansion of the Airy function. crystal with t…
The structure−property relationships of nanostructured Ru/carbon aerogel composite materials have been evaluated. These new materials were prepared via a novel two-step metal vapor impregnation method which enables one to control the Ru loading through repetition of the process. The resulting microstructure is charact…
A one dimensional experiment in granular dynamics is carried out to test the thermodynamic theory of weakly excited granular systems [Hayakawa and Hong, Phys. Rev. Lett. {\bf 78}, 2764(1997)] where granular particles are treated as spinless Fermions. The density profile is measured and then fit to the Fermi distributi…
The photoluminescence (PL) from 100 nm diamond particles induced by infrared (IR) pulsed excitation [λexc=1064 nm (1.16 eV), τ=10 ns] was observed. The laser light intensity dependence of the PL yield shows that this is the five-photon absorption process (the total energy of excitation 5.8 eV). The PL results from str…
We report that common gases (such as He, Ar, ${\mathrm{H}}_{2}$, ${\mathrm{O}}_{2}$, ${\mathrm{N}}_{2}$, CO) experience adsorption at oxidized silicon surfaces at 300 K via electrostatic coupling. This is deduced using contact potential measurements of the work function for gas pressure in the range ${10}^{\ensuremath…
Time-resolved degenerate-four-wave-mixing measurements were used to study the nonlinear optical response (intensity-dependent refractive index) of Ge nanocrystallites embedded in a silica matrix. Nanocrystals were fabricated by ion-implanting silica with 1.0 MeV Ge ions to fluences in the range from 0.6 to 3×1017 Ge c…
Ferroelectric films with composition gradients normal to the substrate have recently been reported to exhibit anomalously large polarization offsets when hysteresis loops are driven with an ac voltage and measured using a Sawyer–Tower (ST) circuit. These offsets have been reported in graded Pb(Zr, Ti)O3 (over 400 μC/c…
The phase Hamiltonian of armchair carbon nanotubes at half filling and away from it is derived from the microscopic lattice model by taking the long-range Coulomb interaction into account. We investigate the low-energy properties of the system using the renormalization group method. At half filling, the ground state i…
Using scanning tunneling microscopy, low-energy ion scattering, and quantitative low-energy electron diffraction, we find about $17%$ metal vacancies on the oxygen-covered Cr(100) surface. The oxygen atoms occupy all the hollow sites of the first layer, including those neighboring a Cr vacancy. We argue that the vacan…
A parallel approach for fabricating nanocrystal-based semiconductor–insulator–metal tunnel diodes is presented. The devices consisted of a Au electrode, a monolayer of 38 Å CdSe nanocrystals, an insulating bilayer of eicosanoic acid (C19H39CO2H), and an Al electrode. Each device was approximately 100 μm2. Conductance…
We report on a photoinduced phenomenon in solids, namely, photomelting at low temperature. We have found that both trigonal and amorphous selenium can be molten by illumination with light at a temperature of ∼77 K. This phenomenon is pure optical (athermal) and it is associated with light-induced breaking of the inter…